National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 

Chihuahuan Desert Network 

Vital Signs Monitoring Plan 

Natural Resource Report NPS/CHDN/NRR—2010/188 
ON THE COVER 

Clockwise from upper left to bottom right: Carlsbad Caverns National Park, Guadalupe Mountains National Park, Fort Davis 

National Historic Site, Big Bend National Park, White Sands National Monument (by Pete Mananen), Amistad National 

Recreation Area. NPS photos unless otherwise noted. 
Chihuahuan Desert Network 

Vital Signs Monitoring Plan 

Natural Resource Report NPS/CHDN/NRR—2010/188 

National Park Service 

Chihuahuan Desert Inventory and Monitoring Network 

Genesis C Building 

New Mexico State University 

Las Cruces, NM 88003 

April 2010 

U.S. Department of the Interior 

National Park Service 

Natural Resource Program Center 

Fort Collins, Colorado
ii 

The National Park Service, Natural Resource Program Center publishes a range of reports that address 

natural resource topics of interest and applicability to a broad audience in the National Park Service and 

others in natural resource management, including scientists, conservation and environmental 

constituencies, and the public. 

The Natural Resource Report Series is used to disseminate high-priority, current natural resource 

management information with managerial application. The series targets a general, diverse audience, and 

may contain NPS policy considerations or address sensitive issues of management applicability. 

All manuscripts in the series receive the appropriate level of peer review to ensure that the information is 

scientifically credible, technically accurate, appropriately written for the intended audience, and designed 

and published in a professional manne. This report received formal, high-level peer review based on the 

importance of its content, or its potentially controversial or precedent-setting nature. Peer review was 

conducted by highly qualified individuals with subject area technical expertise and was overseen by a 

peer review manager. 

Views, statements, findings, conclusions, recommendations, and data in this report are those of the 

author(s) and do not necessarily reflect views and policies of the National Park Service, U.S. Department 

of the Interior. Mention of trade names or commercial products does not constitute endorsement or 

recommendation for use by the National Park Service. 

This report is available from the Chihuahuan Desert Network, 

http://science.nature.nps.gov/im/units/chdn/, and the Natural Resource Publications Management website, 

http://www.nature.nps.gov/publications/NRPM. 

Please cite this publication as: 

National Park Service, Chihuahuan Desert Inventory and Monitoring Network. 2010. Chihuahuan Desert 

Network vital signs monitoring plan. Natural Resource Report NPS/CHDN/NRR—2010/188. National 

Park Service, Fort Collins, Colorado. 

NPS 960/101911, April 2010 
iii 

In Memory

DR. WILLIAM “BILL” H. REID 

November 11, 1933–May 11, 2006 

This plan is dedicated to Bill Reid, our friend and colleague. Bill played an integral role in the early 

stages of the Chihuahuan Desert Network I&M program, leading the biological inventory field efforts for 

several years and serving as the first network program manager and data manager of this fledgling 

program. Bill significantly contributed to the Phase I report by writing the Climate Summary Report of 

CHDN park units and the Phase I Water Quality Assessment report, despite being seriously ill during 

those months. Bill’s contributions laid the foundation for future work and direction of the network. Bill 

always had a love for education and adventure, as evidenced in his life experiences. Though Bill was 

known by his National Park Service colleagues as a talented and dedicated ecologist, this was a career 

move he undertook later in life. Bill was first involved with designing rockets in the Apollo space 

program for NASA. Bill was also a prolific writer, having published hundreds of articles and papers, as 

well as several novels. His enthusiasm and unwavering dedication for his work, the natural world, and to 

his friends and family were an inspiration for everyone he encountered. Bill taught us never to believe in 

first impressions, and to always give your colleagues and friends the benefit of the doubt. He understood 

the meaning of friendship. Bill is sorely missed.

v 

Contents 

Figures ........................................................................................................................................................ix 

Tables..........................................................................................................................................................xi 

Acronyms..................................................................................................................................................xiii 

Executive Summary..................................................................................................................................xv 

Acknowledgements .................................................................................................................................xix 

Chapter 1: Introduction ..............................................................................................................................1

1.1 Background .........................................................................................................................................1 

1.2 Guidance.............................................................................................................................................2 

1.2.1 Goals of vital signs monitoring in the Chihuahuan Desert Network.............................................2 

1.2.2 Legislation, policy and guidance..................................................................................................3 

1.2.3 Park-specific enabling legislation.................................................................................................4 

1.2.4 The Government Performance and Results Act..........................................................................4 

1.3 Overview and Ecological Characteristics of the Chihuahuan Desert Network ...................................5 

1.3.1 Ecoregions encompassing CHDN parks .....................................................................................5 

1.3.2 Climate.........................................................................................................................................7 

1.3.3 Elevation, landform, and soils......................................................................................................8 

1.3.4 Water and hydrology..................................................................................................................10 

1.3.5 Flora and plant communities......................................................................................................11 

1.3.6 Fauna.........................................................................................................................................13 

1.3.7 Ecosystems of CHDN park units................................................................................................14 

1.4 Park Natural Resources Issues and Management Concerns...........................................................19 

1.4.1 Issues identified in park interviews and network scoping ..........................................................19 

1.4.2 General management plans and resource stewardship strategies ...........................................20 

1.4.3 State comprehensive wildlife conservation strategy..................................................................20 

1.4.4 Vital signs monitoring in Mexico.................................................................................................20 

1.5 Designing an Integrated Monitoring Program for the Chihuahuan Desert Network .........................21 

1.5.1 CHDN approach to vital signs monitoring..................................................................................22 

1.6 Summary of Current Monitoring Within and Surrounding the Network.............................................23 

1.6.1 Air quality monitoring .................................................................................................................24 

1.6.2 Water resources monitoring.......................................................................................................26 

Chapter 2: Conceptual Models ................................................................................................................27 

2.1 Conceptual Models ...........................................................................................................................27 

2.2 Conceptual Model Approach.............................................................................................................27 

2.3 Summary of Conceptual Models for Six Chihuahuan Desert Network Ecosystems.........................30 

2.3.1 Desert Ecosystem......................................................................................................................30 

2.3.2 Foothill Ecosystem.....................................................................................................................37 

2.3.3 Montane Ecosystem ..................................................................................................................41 

2.3.4 Reservoir Ecosystem .................................................................................................................45 

2.3.5 River Ecosystem ........................................................................................................................49 

2.3.6 Dune Ecosystem........................................................................................................................54 

Chapter 3: Vital Signs...............................................................................................................................59 

3.1 Introduction........................................................................................................................................59 

3.2 Overview of Vital Signs Selection Process .......................................................................................59 

3.2.1 Park-level vital signs scoping workshops (2004–2005).............................................................61 

3.2.2 Network-level vital signs prioritization workshop (2006)............................................................61 

3.2.3 Selection of core vital signs (2006–2008)..................................................................................62 

3.3 Justification for Vital Signs ................................................................................................................66 

3.3.1 Air and climate ...........................................................................................................................66 

3.3.2 Geology and soils ......................................................................................................................66 

3.3.3 Water..........................................................................................................................................68 
vi 

3.3.4 Biological integrity ......................................................................................................................68 

3.3.5 Landscape dynamics .................................................................................................................69 

3.4 Links of Vital Signs to Conceptual Models........................................................................................70 

Chapter 4: Sample Design........................................................................................................................73 

4.1 Introduction........................................................................................................................................73 

4.2 Sampling Design Concepts and Definitions......................................................................................73 

4.2.1 Overview of sampling designs ...................................................................................................73 

4.2.2 Sample size considerations and magnitude of change .............................................................76 

4.3 Sampling Design by Vital Sign..........................................................................................................77 

Chapter 5: Monitoring Protocols .............................................................................................................81 

5.1 Protocol Overview .............................................................................................................................81 

5.2 Protocol Development Process.........................................................................................................81 

5.3 Protocol Development Summaries ...................................................................................................87 

Chapter 6: Data Management ..................................................................................................................89 

6.1 Introduction........................................................................................................................................89 

6.2 Data Management Plan ....................................................................................................................89 

6.2.1 Data accuracy ............................................................................................................................89 

6.2.2 Data security ..............................................................................................................................89 

6.2.3 Data longevity ............................................................................................................................89 

6.2.4 Data accessibility .......................................................................................................................90 

6.3 Data Sources and Priorities ..............................................................................................................90 

6.4 Data Management Categories ..........................................................................................................91 

6.5 Data Management and the Project Life Cycle ..................................................................................92 

6.6 Water Quality Data............................................................................................................................94 

6.7 Data Management Plan Maintenance...............................................................................................94 

6.8 Implementation..................................................................................................................................95 

Chapter 7: Data Analysis and Reporting ................................................................................................97 

7.1 Strategies and Key Audiences for Analysis and Reporting of Monitoring Results ...........................97 

7.2 Data Analysis ....................................................................................................................................99 

7.3 Communications and Reporting........................................................................................................99 

7.3.1 Annual reports for specific protocols and projects...................................................................106 

7.3.2 Annual briefings to park managers ..........................................................................................106 

7.3.3 Resource briefs........................................................................................................................106 

7.3.4 Analysis and synthesis reports ................................................................................................106 

7.3.5 Protocol and program reviews .................................................................................................107 

7.3.6 Natural resource summary table..............................................................................................107 

7.3.7 Scientific journal articles, book chapters, and presentations at scientific meetings ................107 

7.3.8 Network Internet and Intranet websites ...................................................................................108 

7.3.9 Learning Center of the American Southwest...........................................................................108 

Chapter 8: Administration and Implementation...................................................................................109 

8.1 Core Duties .....................................................................................................................................109 

8.2 Board of Directors ...........................................................................................................................110 

8.3 Technical Committee ......................................................................................................................111 

8.4 Staffing Plan....................................................................................................................................112 

8.4.1 Program manager ....................................................................................................................115 

8.4.2 Science advisor........................................................................................................................115 

8.4.3 Data manager ..........................................................................................................................115 

8.4.4 Field coordinator ......................................................................................................................115 

8.4.5 Budget analyst .........................................................................................................................115 

8.4.6 Administrative assistant ...........................................................................................................116 

8.4.7 Ecologist...................................................................................................................................116 
vii 

8.4.8 GIS specialist ...........................................................................................................................116 

8.4.9 GIS/Data management technician...........................................................................................116 

8.4.10 University interns and other associated positions..................................................................116 

8.4.11 Field efforts ............................................................................................................................117 

8.5 Program Integration ........................................................................................................................117 

8.6 Partnerships ....................................................................................................................................117 

8.7 Program Review Process................................................................................................................118 

Chapter 9: Schedule ...............................................................................................................................121 

9.1 Phased Start-up Schedule for Protocol Development ....................................................................121 

9.2 Protocol Implementation Schedule .................................................................................................121 

9.3 Programmatic reviews.....................................................................................................................123 

Chapter 10: Budget.................................................................................................................................125 

Chapter 11: Literature Cited...................................................................................................................129 

Glossary of Terms and Concepts..........................................................................................................145 
 
ix 

Figures

Figure 1.1. Relationships between monitoring, inventories, research, and natural resource management activities in 

national parks (modified from Jenkins et al. 2002).........................................................................................................2 

Figure 1.3.2. Walter’s climate diagram for CHDN park units (n = 8 stations; 2 from BIBE)............................................8 

Figure 1.3.3-1. Mexican spotted owl roosting in a chinquapin oak in a canyon in Guadalupe Mountains National 

Park..............................................................................................................................................................................10 

Figure 1.3.3-2. Little white whiptail lizard adapted to dunes.........................................................................................10 

Figure 1.3.7A–F. Ecosystems of Chihuahuan Desert Network parks...........................................................................18 

Figure 1.5. The conceptual framework for categorizing CHDN vital signs (adapted from Woodley 1993). ..................21 

Figure 2.2-1. Illustration of the Jenny-Chapin model, showing relationships among state factors, interactive 

controls, and ecosystem processes (modified from Figure 2.1.1 in Britten et al. 2007). ..............................................28 

Figure 2.2-2. Illustration of the hierarchical conceptual model scheme used to identify vital signs for monitoring 

(O’Dell et al. 2005). ......................................................................................................................................................29 

Figure 2.3.1. Ecosystem characterization model for the CHDN Desert Ecosystem. ....................................................32 

Figure 2.3.2. Ecosystem characterization model for the CHDN Foothill Ecosystem. ...................................................38 

Figure 2.3.3. Ecosystem characterization model for the CHDN Montane Ecosystem..................................................42 

Figure 2.3.4. Ecosystem characterization model for the CHDN Reservoir Ecosystem. ...............................................46 

Figure 2.3.5. Ecosystem characterization model for the CHDN River Ecosystem. ......................................................50 

Figure 2.3.6. Ecosystem characterization model for the CHDN Dune Ecosystem. ......................................................55 

Figure 6.5. Model of data life cycle stages. ..................................................................................................................93 

Figure 6.6. Data flow diagram for water quality data....................................................................................................94 

Figure 7.1 Relationships between analyses, reporting, research, and Chihuahuan Desert Network program goals 

(adapted from Chung-MacCoubrey et al. 2008)...........................................................................................................98 
x 
xi 

Tables 

Chihuahuan Desert Network monitoring protocols by vital sign and park. .................................................................. xvi 

Table 1.2.4. Government Performance and Results Act goals specific to CHDN parks and relevant to the monitoring 

plan. ...............................................................................................................................................................................4 

Table 1.3.5. Terrestrial habitat types of the Chihuahuan Desert Ecoregion. ................................................................12 

Table 1.3.7-1. Biophysical summary of Chihuahuan Desert Network parks.................................................................16 

Table 1.3.7-2. Classification, area, and distribution of ecosystems within CHDN national parks. ................................17 

Table 1.6. Record of historic (H, >5 years ago) or current (C) monitoring data for CHDN parks..................................23 

Table 2.3.1. Key degradation processes in the Desert Ecosystem, stressors and ecological effects associated with 

these processes, and potential measures that would characterize degradation processes and effects.......................36 

Table 2.3.2. Key degradation processes in the Foothill Ecosystem, stressors and ecological effects associated with 

these processes, and potential measures that would characterize degradation processes and effects.......................40 

Table 2.3.3. Key degradation processes in the Montane Ecosystem, stressors and ecological effects associated with 

these processes, and potential measures that would characterize degradation processes and effects.......................44 

Table 2.3.4. Key degradation processes in the reservoir ecosystem, stressors and ecological effects associated with 

these processes, and potential measures that would characterize degradation processes and effects.......................48 

Table 2.3.5. Key degradation processes in the River Ecosystem, stressors and ecological effects associated with 

these processes, and potential measures that would characterize degradation processes and effects.......................53 

Table 2.3.6. Key degradation processes in the Dune Ecosystem, stressors and ecological effects associated with 

these processes, and potential measures that would characterize degradation processes and effects.......................58 

Table 3.2. Events and associated outcomes in the steps followed to identify and prioritize CHDN vital signs.............60 

Table 3.2.3. Chihuahuan Desert Network core vital signs, presented by park and funding category within the context 

of the NPS Ecological Monitoring Framework..............................................................................................................64 

Table 3.4. Linkage of vital signs to valued resources and key issues (physical drivers and stressors) from conceptual 

ecosystem models. ......................................................................................................................................................71 

Table 4.3. Summary of Chihuahuan Desert Network sample design specification by protocol....................................78 

Table 5.1. CHDN protocols with relevant vital signs, parks included, justifications, and monitoring objectives............82 

Table 6.2.4. Data to be provided on the CHDN and national I&M web sites. ...............................................................90 

Table 7.2. Four general approaches to data analysis for Chihuahuan Desert Network vital signs, and the lead analyst 

responsible.................................................................................................................................................................100 

Table 7.3-1. Summary of proposed products for the Chihuahuan Desert Network. ...................................................102 

Table 8.2. Composition of the Chihuahuan Desert Network Board of Directors (as of March 2010)..........................111 

Table 8.3. Composition of the Chihuahuan Desert Network Technical Committee....................................................112 

Table 8.4. Current and proposed Chihuahuan Desert Network staff positions and their primary duties. ...................113 

Table 8.6. Key partnerships for the Chihuahuan Desert Network, FY10–FY13. ........................................................119 
xii 

Table 9.1. Tasks to be accomplished before full monitoring is implemented. ............................................................122 

Table 9.2-1. Development (D), pilot testing (P), and implementation (I) schedule for each protocol, calendar years 

2009–2013. ................................................................................................................................................................123 

Table 9.2-2. General estimate of months when data collection could occur for CHDN protocols. .............................123 

Table 10. Detailed budget for the Chihuahuan Desert Network Vital Signs Monitoring Program in the first year of 

implementation after review and approval of the monitoring plan. .............................................................................126 
xiii 

Acronyms 

ac acres 

AMIS Amistad National Recreation Area 

AQRV Air-quality-related values 

BIBE Big Bend National Park 

BOD Board of Directors 

BSC biological soil crust 

CAVE Carlsbad Caverns National Park 

CC Área de Protección de Flora y Fauna Cuatrociénegas 

CESU Cooperative Ecosystem Studies Unit 

CH4 methane 

CHDN Chihuahuan Desert Network 

CO2 carbon dioxide 

CONANP National Commission of Protected Natural Areas 

DMP Data Management Plan 

DOC dissolved organic carbon 

EPA Environmental Protection Agency 

Fe iron 

FODA Fort Davis National Historic Site 

ft feet 

FTE full-time equivalent 

FY fiscal year 

GIS geographic information systems 

GMP general management plan 

GPRA Government Performance and Results Act 

GRTS Generalized Random Tessellation Stratified 

GRYN Greater Yellowstone Network 

GUMO Guadalupe Mountains National Park 

H2S hydrogen sulfide 

ha hectares 

I&M inventory and monitoring 

IBWC International Boundary and Water Commission 

IMR Intermountain Region 

in inches 

IT information technology 

km kilometers 

m meters 

Mn manganese 

MS Microsoft 

NHS national historic site 

NM national monument 

NP national park 

NPS National Park Service 

NRA national recreation area 

O2 oxygen 

OMB U.S. Office of Management and Budget 

ONRW Outstanding National Resource Waters 

PI principal investigator 

POC particulate organic carbon 

ppm parts per million 

QA/QC quality assurance/quality control 
xiv 

RIGR Rio Grande Wild and Scenic River 

RMBO Rocky Mountain Bird Observatory 

ROMN Rocky Mountain Network 

SODN Sonoran Desert Network 

SOPN Southern Plains Network 

SOPs standard operating procedures 

TBD to be determined 

TC Technical Committee 

TCEQ Texas Commission on Environmental Quality 

WASO Washington Support Office 

WHSA White Sands National Monument 

WSR wild and scenic river 
xv 

Executive Summary 

Knowing the condition of natural resources in national parks is fundamental to the ability of the National 

Park Service (NPS) to manage park resources “unimpaired for the enjoyment of future generations.” To 

more fully meet its mission, the NPS has implemented a strategy, funded by the Natural Resource 

Challenge, to programmatically institutionalize natural resource inventory and monitoring. This effort 

was undertaken to ensure that NPS units with significant natural resources possess the information needed 

for effective, science-based resource management decisionmaking. The national strategy consists of a 

framework with three major components: (1) completion of basic resource inventories upon which 

monitoring efforts can be based; (2) creation of experimental prototype monitoring programs to evaluate 

alternative monitoring designs and strategies; and (3) implementation of ecological monitoring in all 

parks with significant natural resources. 

To facilitate collaboration and information sharing among parks with similar natural resource issues, and 

to achieve economies of scale in inventory and monitoring, the NPS organized the more than 270 parks 

with significant natural resources into 32 ecoregional networks. Parks within each network work together 

and share funding and professional staff to plan, design, and implement an integrated long-term 

monitoring program. The Chihuahuan Desert Inventory and Monitoring Network (CHDN) is composed of 

seven park units in Texas and New Mexico: Amistad National Recreation Area (AMIS), Big Bend 

National Park (BIBE), Carlsbad Caverns National Park (CAVE), Fort Davis National Historic Site 

(FODA), Guadalupe Mountains National Park (GUMO), Rio Grande Wild & Scenic River (RIGR, 

managed by BIBE), and White Sands National Monument (WHSA). The CHDN monitoring program is 

designed to complement, not replace, existing park and other agency monitoring programs. Funding for 

the CHDN program supports a core, professional I&M staff who conduct the day-to-day activities of the 

network. The core staff collaborate with staff from the network parks and other programs and agencies to 

implement an integrated long-term program for monitoring high-priority vital signs. 

The program is designed to ensure that monitoring addresses critical information needs of park managers 

and produces ecologically relevant, scientifically credible data that are accessible to park managers, 

planners, and other key audiences. The monitoring program will leverage its funding through 

collaborative partnerships with other programs, agencies, and academia. This monitoring plan is the 

foundation of the CHDN monitoring program. The plan is the result of a multi-year investment in 

program development. 

The complex task of developing ecological monitoring requires a front-end investment in planning and 

design to ensure that monitoring will meet the most critical information needs and produce ecologically 

relevant and scientifically credible data that are accessible to managers in a timely manner. The CHDN 

monitoring program is being developed over four years, with specific objectives and reporting 

requirements for each of three planning phases. This final vital signs monitoring plan: 

1. Outlines CHDN monitoring goals and the planning process used to develop the monitoring 

program (Chapter 1); 

2. Summarizes existing information concerning park natural resources and resource management 

issues across the network (Chapter 1); 

3. Provides a conceptual model framework for CHDN park ecosystems (Chapter 2); 

4. Selects and prioritizes vital signs (Chapter 3); 

5. Presents a sampling framework for aquatic and terrestrial ecosystems in parks (Chapter 4); 

6. Summarizes monitoring protocols (Chapter 5); 
xvi 

7. Describes the network’s approach to data management (Chapter 6); and 

8. Provides information on program administration, operations, and funding (Chapters 8-10, 

respectively). 

The diversity of ecosystems in CHDN parks, the geographic distribution of these parks, and differences in 

resource management priorities among parks are perhaps the greatest challenges facing the network. 

However, the vital signs selection process found that parks share a number of similar resource 

management issues and monitoring needs. The vital signs selection process also recognized that highpriority, park-specific needs should be addressed to the extent possible. This balance between identifying 

common needs and addressing park-specific issues will continue to be important as the CHDN 

implements long-term vital signs monitoring of parks. 

This CHDN vital signs monitoring plan identifies the suite of vital signs for monitoring. To monitor these 

vital signs, the network will prepare and implement 10 monitoring protocols in selected parks over the 

next 2–3 years. When possible, the CHDN will implement protocols used by other networks to increase 

efficiency and facilitate evaluation across greater spatial scales. Protocols, the vital signs to which they 

correspond, and the parks where they will be monitored are shown in the table below. 

Chihuahuan Desert Network monitoring protocols by vital sign and park. 

Protocol Vital sign(s) 

AMIS BIBE CAVE FODA GUMO RIGR WHSA 

Air Quality Ozone 

Wet and Dry Deposition 

Visibility and Particulate Matter 

X y X 

Climate Basic Meteorology X X X X X X

Dune Dynamics Dune Formation and Stability 

Dune Morphology y X

River Channel Morphology River Channel Characteristics y X y 

Groundwater Quantity Groundwater Quantity X X X X X X

Surface Water Quality and Dynamics Surface Water Dynamics 

Persistence of Springs 

Surface Water Quality 

Aquatic Invertebrates 

X X X X 

Invasive/Non-native Plants Invasive/Non-native Plants X X X X X X X 

Landbirds Bird Communities X X X X X X X 

Integrated Uplands (Soils and Vegetation) Plant Community Composition 

Soil Hydrologic Function 

Biological Soil Crusts 

Soil Erosion (Wind and Water) 

Bare Ground 

 X X X X X 

Landscape Patterns and Dynamics Land Cover 

Land-Use Changes X X X X X X 

y = This park will be monitored if resources permit. 
xvii 

Network I&M staff and their cooperators make thousands of observations each year about plant and 

animal populations, communities, and their environments. In essence, the purpose of data management is 

to ensure that an accurate and complete record of those observations is maintained in perpetuity. The 

CHDN Data Management Plan identifies key data resources and processes to manage inventory and 

monitoring data. Assuring and maintaining data integrity is fundamental to the CHDN mission and 

requires a considerable investment of staff time. Data management procedures follow five key steps: 

acquisition, verification, validation, analysis, and dissemination. In addition, storage, maintenance, and 

security issues apply to all stages of data flow. 

Reporting is the process through which we derive information from data through analysis and 

interpretation for use by park managers. Vital signs reporting will include annual reports for specific 

protocols and projects; annual briefings to park managers; resource briefs; analysis and synthesis reports; 

protocol and program reviews; natural resource summary tables; scientific journal articles and book 

chapters, and presentations at scientific meetings; and postings to network Internet and Intranet websites 

and the Learning Center of the American Southwest. To promote efficient reporting, data management 

efforts during the summary and analysis phase will focus on automation of routine reports. Summary 

analysis for annual reports of vital signs monitoring studies will include graphed results and descriptive 

statistics (mean, standard deviation, sample size) for all of the primary variables included in the project. 

Five to ten-year trend reports will typically include correlation and trends analysis. 

Administrative oversight for the program originates from the CHDN Board of Directors (BOD) and 

Technical Committee (TC). The BOD, composed of the superintendents of six parks, is charged with 

oversight of the network. The TC is composed of natural resource managers from each CHDN park and 

serves as the scientific and operational body of the network that develops recommendations on how 

monitoring is implemented. The CHDN program manager is supervised by the Intermountain Region 

I&M program manager with input from the BOD. In turn, the program manager, or his/her subordinates, 

supervise all I&M staff. Currently, the CHDN employs three permanent and one term employee, and two 

students from New Mexico State University. 

Two principal sources of funding are combined to support operations of the CHDN: vital signs 

monitoring funds from the Natural Resource Challenge ($799,400 in FY10) and $66,700 (in FY10) for 

water quality monitoring from the NPS Water Resources Division. All funds are managed by the program 

manager under the oversight of the BOD. An annual work plan that directs expenditure of funds is 

developed with input from the TC and approved by the BOD. All I&M program funds must be accounted 

for and disclosed in an annual administrative report, reviewed by the BOD. 

The CHDN will be subject to periodic reviews to ensure high program quality and accountability. This 

monitoring plan was approved by the Washington Support Office monitoring leader in 2010. In 2013, and 

every fifth year thereafter, a comprehensive review of program operations will be conducted. Peer review 

of monitoring protocols will be conducted by the IMR I&M program manager upon their completion and 

prior to implementation. 

xix 

Acknowledgements 

This monitoring plan could not have been completed without the commitment, hard work, and support of 

network staff, park staff, and external cooperators. Specifically, the CHDN would like to acknowledge the 

following people for developing and authoring sections of this plan: Hildy Reiser (Chapters 1, 3, 5, 7, 8, 

9, 10, appendices), Steve Garman (Chapters 2, 4), Missy Powell (Chapter 11), Tom Richie (Chapter 6), 

James P. Ward, Jr. (Chapters 2, 4) and Kirsten Gallo (Chapters 4, 5, 8, 9, 10). Ann Lewis and Alice 

Wondrak Biel provided invaluable editorial assistance. 

For their past and continued support as the CHDN Board of Directors, we thank recent and current BOD 

members John Morlock (Chair), John Benjamin, Bruce Bingham, Todd Brindle, Alan Cox, Chuck Hunt, 

John King, John Lujan, Kevin Schneider, and Bill Wellman. We would not have been able to progress 

without the participation, advice, and support of the CHDN Technical Committee. Current and recent 

committee members include Fred Armstrong (Chair), David Bustos, Bill Conrod, Vidal Davila, Greg 

Garetz, John Heiner, Gopaul Noojibail, Raymond Skiles, Rick Slade, Renee West, Diane White, Barbara 

Wilson, Phil Wilson, and Jan Wobbenhorst. 

The CHDN would especially like to thank all those who helped to develop this plan and contributed to 

earlier versions. Special thanks and gratitude (in alphabetical order) to Renee Barker, Gorden Bell, Jeff 

Bennett, Brandon Bestelmeyer, Jennifer Blakesley, Ken Boykin, Paul Burger, Andrea Ernst, Ryan Ewing, 

Yvette Garcia, Steve Garman, Bob Gitzen, Jenny Good, Al Groeger, David Hanni, Kris Havstad, Jonena 

Hearst, Jeff Herrick, Lou Hillman, Rick Huff, Kris Johnson, Richard “Rip” Langford, Chris Lauver, Ann 

Lewis, Peter Lindstrom, Glenn Longley, Gary Kocurek, Chris Maher, Tonnie Maniero, Rayo 

McCollough, Barbara Meyers, Terry Neville, Dale Pate, Ellen Porter, Stephan Porter, the late W. H. 

“Bill” Reid, Gary Rosenlieb, Scott Schrader, Ariel Simpson, Joe Sirotnak, Raymond Slade, Jr., Mike 

Story, Liz Walsh, and Kendal Young. 

The CHDN continues to benefit immensely from the work of other networks. We gratefully acknowledge 

the networks whose work we used as examples and, in some cases, used directly to help create this plan, 

especially the Greater Yellowstone Network, Gulf Coast Network, Heartland Network, Mojave Desert 

Network, Northern Colorado Plateau Network, Northern Great Plains Network, Rocky Mountain 

Network, Sonoran Desert Network, South Florida/Caribbean Network, Southern Colorado Plateau 

Network, and Southern Plains Network. Collectively, the staffs of the I&M networks are among the most 

dedicated, bright, and creative individuals working on monitoring issues in federal and state land 

management agencies. We are proud to be associated with them. 

1 

Chapter 1: Introduction 

1.1 Background 

Knowing the condition and trends of natural resources in national parks is fundamental to the National 

Park Service’s (NPS) ability to manage park resources “unimpaired for the enjoyment of future 

generations.” National park managers across the country are confronted with increasingly complex and 

challenging issues that require a broad-based understanding of the status and trends of park resources as a 

basis for making decisions, and for working with other agencies and the public for the benefit of park 

resources. 

An essential tool for natural resource stewardship in the NPS is the use of monitoring. Ecological 

monitoring establishes reference conditions for natural resources that can be used to detect future changes 

and determine whether observed changes are within natural levels of variability or may be indicators of 

unwanted human influences. Monitoring results may also be used to determine what constitutes 

impairment and to identify the need to initiate or change management practices. Natural resource 

monitoring offers park-specific information needed to understand and identify changes in complex, 

variable, and imperfectly understood natural systems (i.e., threats from air and water pollution, climate 

change, and invasive/non-native species originating outside park boundaries). Monitoring provides a basis 

for understanding and identifying meaningful change in natural systems (Roman and Barrett 1999). 

Accordingly, in 1999, the NPS launched the Natural Resource Challenge, a program designed to 

strengthen natural resource management in the nation’s national parks (NPS 1999). The single biggest 

undertaking of the Challenge was to augment ongoing park inventory and monitoring efforts into an 

ambitious, comprehensive, nationwide program. The servicewide natural resources inventory and 

monitoring (I&M) program was introduced to 270 parks identified as having significant natural resources. 

Under this program, parks were organized into 32 networks based on similar geographic and natural 

resource characteristics, allowing for improved efficiency and sharing of staff and resources (Fancy et al. 

2009). The Chihuahuan Desert Network (CHDN) is one of those 32 networks. 

Over a multi-year period, the CHDN Vital Signs Monitoring Plan was developed following specific 

guidance from the NPS Washington Support Office (WASO) (NPS 2006a). This plan describes the 

process for selection of and the plan for monitoring “vital signs” of the natural resources in Amistad 

National Recreation Area (AMIS); Big Bend National Park (BIBE) and Rio Grande Wild and Scenic 

River (RIGR), administered by BIBE; Carlsbad Caverns National Park (CAVE); Fort Davis National 

Historic Site (FODA); Guadalupe Mountains National Park (GUMO); and White Sands National 

Monument (WHSA). 

“Vital signs,” as defined by the NPS, are a subset of physical, chemical, and biological elements and 

processes of park ecosystems that are selected to represent the overall health or condition of park 

resources or elements that have important human values. The elements and processes that are monitored 

are a subset of the total suite of natural resources that park managers are directed to preserve, including 

water, air, geological resources, plants and animals, and the various ecological, biological, and physical 

processes that act on those resources. The broad-based, scientifically sound information obtained through 

natural resource inventories and monitoring will have multiple applications for management 

decisionmaking, research, education, and promoting public understanding of park resources (Figure 1.1). 
2 

Inventory

Monitoring

Research Resource

Management

Objective

Achieved?

Change

Detected?

Cause

Understood?

Intervention

Needed?

Yes

No

Yes

Yes

No

Identifies trends and natural

variation in resources

Determines

management

effectiveness

No

No

Yes

Figure 1.1. Relationships between monitoring, inventories, research, and natural resource management activities in 

national parks (modified from Jenkins et al. 2002). 

1.2 Guidance 

1.2.1 Goals of vital signs monitoring in the Chihuahuan Desert Network 

The overall goal of the servicewide I&M program is to develop scientifically sound information on the 

current status and long-term trends in the composition, structure, and function of park ecosystems, and to 

determine how well current management practices are sustaining those ecosystems (Fancy et al. 2009). 

The five NPS servicewide and CHDN vital signs monitoring goals are: 

1. Determine status and trends in selected indicators of the condition of park ecosystems to allow 

managers to make better-informed decisions and to work more effectively with other agencies 

and individuals for the benefit of park resources. 

2. Provide early warning of abnormal conditions of selected resources to help develop effective 

mitigation measures and reduce costs of management. 

3. Provide data to better understand the dynamic nature and condition of park ecosystems and to 

provide reference points for comparisons with other, altered environments. 

4. Provide data to meet certain legal and congressional mandates related to natural resource 

protection and visitor enjoyment. 

5. Provide a means of measuring progress toward performance goals. 

Clearly articulated goals and objectives help define all aspects of a program, including the choice of vital 

signs to be monitored. CHDN objectives will be developed for each individual vital sign. 
3 

1.2.2 Legislation, policy and guidance 

With the passage of the National Park Service Organic Act of 1916 (16 USC 1§1), the mission of the 

National Park Service was established and defined, and through it Congress implied the need to monitor 

natural resources and guarantee unimpaired park services: 

“The service thus established shall promote and regulate the use of the Federal areas 

known as national parks, monuments, and reservations hereinafter specified . . . by such 

means and measures as conform to the fundamental purpose of the said parks, 

monuments, and reservations, which purpose is to conserve the scenery and the natural 

and historic objects and the wild life therein and to provide for the enjoyment of the same 

in such manner and by such means as will leave them unimpaired for the enjoyment of 

future generations.” 

Congress reaffirmed the declaration of the Organic Act vis-à-vis the General Authorities Act of 1970 (16 

USC 1a–1a8), effectively ensuring that all park units be united into the “National Park System” by a 

common purpose of preservation, regardless of title or designation. Several decades later, NPS 

management policy reiterated the importance of this protective function of the agency to “understand, 

maintain, restore, and protect the inherent integrity of the natural resources” (NPS 2001). 

More recent and specific requirements for a program of inventory and monitoring park resources are 

found in the National Parks Omnibus Management Act of 1998 (Public Law 105-391). One intent of the 

Act was to create an inventory and monitoring program that may be used “. . . to establish baseline 

information and to provide information on the long-term trends in the condition of National Park System 

resources.” In 2001, NPS managers updated previous policy and specifically directed the NPS to 

inventory and monitor natural systems in efforts to inform park management decisions (NPS 2001). 

The NPS Water Resources Division provides explicit guidance and funding for the water quality 

component of each of the 32 networks’ monitoring programs. Design and implementation of water quality 

monitoring is fully integrated with the network vital signs monitoring design process (including staffing, 

planning, and design) to facilitate integration within the context of a comprehensive network monitoring 

program. The NPS goal is to rely on its own uniform monitoring data and use it to protect water 

resources. Monitoring of water quality also is supported through legislation, policy, and guidance as 

described above. Each I&M network is required to (1) determine priorities for impaired water and pristine 

water monitoring; (2) define site-specific monitoring objectives; and (3) develop water quality monitoring 

plans. 

Additional legislation is intended not only to protect the natural resources within national parks and other 

federal lands, but also to address concerns over the environmental quality of life in the United States. NPS 

units are among some of the most secure areas for sustaining populations of threatened and endangered 

species, and contain natural resources that are compromised in other parts of the country. Therefore, the 

guidance offered by federal environmental legislation and policy is an important component of the 

development and administration of a natural resource inventory and monitoring system in the national 

parks (Appendix A). 

Historically significant treaties and conventions relevant to the region also have been documented 

(Appendix B). Due to international concern for environmental quality in the U.S.–Mexico border region, 

national officials have met and initiated bi-national action. 
4 

1.2.3 Park-specific enabling legislation 

The CHDN includes three national parks (NP), one national monument (NM), one national historic site 

(NHS), one national recreation area (NRA), and one wild and scenic river (WSR). Park-specific enabling 

legislation (see Appendix A), as well as international programs, collectively influence natural resource 

management on NPS lands in the CHDN. The enabling legislation of an individual park provides insight 

into the natural and cultural resources values it was created to protect and, in some cases, gives specific 

guidance for the direction and emphasis of resource management programs, including inventory and 

monitoring. 

1.2.4 The Government Performance and Results Act 

The Government Performance and Results Act (GPRA) is central to NPS operations, including the I&M 

program. The NPS has developed a national strategic plan identifying key goals to be met (NPS 2001). A 

list of the national GPRA goals relevant to CHDN parks is located in Table 1.2.4. In addition to the 

national strategic goals, each park has a five-year plan with park-specific GPRA goals relevant to natural 

resource monitoring and management. Once the CHDN monitoring plan is implemented, parks will be 

better able to report on the condition of their resources. 

Table 1.2.4. Government Performance and Results Act goals specific to CHDN parks and relevant 

to the monitoring plan. 

Goal # GPRA Goal Parks with this Goal 

Category 1a: Natural and cultural resources and associated values are protected, restored, and maintained in good 

condition and managed within their broader ecosystem context. 

1a1A Disturbed Lands Restored BIBE, GUMO 

1a1B Invasive/Non-native Plants AMIS, BIBE, CAVE, FODA, GUMO, RIGR, WHSA 

1a1D Land Health – Riparian and Stream Areas BIBE, CAVE, GUMO 

1a1E Land Health – Upland BIBE, CAVE, FODA, GUMO 

1a2 Threatened and Endangered Species AMIS, CAVE, BIBE, GUMO, RIGR, 

1a2B Species of Special Management Concern BIBE 

1a2C Invasive/Non-native Animals AMIS, BIBE, CAVE, GUMO, RIGR, WHSA 

1a3 Air Quality and Wilderness Values BIBE, GUMO 

1a4A Water Quality (Rivers, Streams) AMIS, BIBE, GUMO, RIGR 

1a4B Water Quality (Lakes) AMIS 

1a4C Water Quantity (Protected and/or Restored) BIBE, CAVE, GUMO, RIGR, WHSA 

Category 1b: The NPS contributes to knowledge about natural and cultural resources and associated values; 

management decisions about resources and visitors are based on adequate scholarly and scientific information. 

1b01 Park Natural Resource Data Sets (Inventories) AMIS, BIBE, CAVE, FODA, GUMO, RIGR, WHSA 

1b3A Vital Signs Identified AMIS, BIBE, CAVE, FODA, GUMO, RIGR, WHSA 

1b3B Vital Signs Monitored AMIS, BIBE, CAVE, FODA, GUMO, RIGR, WHSA 
5 

1.3 Overview and Ecological Characteristics of the Chihuahuan 

Desert Network 

The Chihuahuan Desert Network includes seven NPS units in New Mexico and Texas (Table 1.3, 

Appendix C). These park units vary in size from almost 200 ha (~500 ac) at FODA to over 300,000 ha 

(800,000 ac) at BIBE (Table 1.3). In this section, we provide an overview of the CHDN, briefly describe 

ecological factors that influence the types of resources within park boundaries, and discuss salient 

characteristics of each park unit. 

Table 1.3. National Park System units and size in the Chihuahuan Desert 

Network. 

Area 

Unit State Park code Hectares Acres 

Amistad National Recreation Area TX AMIS 23,195 57,292 

Big Bend National Park TX BIBE 324,641 801,863 

Carlsbad Caverns National Park NM CAVE 18,934 46,766 

Fort Davis National Historic Site TX FODA 192 474 

Guadalupe Mountains National Park TX GUMO 34,986 86,416 

Rio Grande Wild and Scenic River* TX RIGR 2,091 5,164 

White Sands National Monument NM WHSA 58,191 143,733 

All CHDN park units 2 7 462,230 1,141,708 

* RIGR is administered by BIBE; the portion within BIBE is 209 river km (127 river miles) long. 

1.3.1 Ecoregions encompassing CHDN parks 

All CHDN park units are geographic entities that can be placed at different levels of a hierarchical 

framework defined by ecological processes. Knowing a network or park unit’s position in a broader-scale 

framework provides an initial step for identifying ecological factors (e.g., broad-scale drivers) that 

influence the nature, distribution, and quantity of park resources and their management. One classification 

level often used to describe I&M networks is the ecoregion. An ecoregion is a relatively 

homogeneous, ecologically distinctive area that has resulted from a combination of climatic, geological, 

landform, soil, vegetative, wildlife, water, and human factors (Environment Canada 2007). Another wellused level is the ecosystem, which is typically a smaller geographic area within an ecoregion. 

The park units of the CHDN are primarily located within the northern extent of the Chihuahuan Desert 

Ecoregion (Figure 1.3.1). The Chihuahuan Desert Ecoregion spans approximately 70 million hectares 

from 1,500 km south of Albuquerque, New Mexico, to 250 km north of Mexico City, including much of 

the Mexican states of Chihuahua, Coahuila, Durango, Zacatecas, and San Luis Potosi, as well as large 

parts of southern New Mexico and the Trans-Pecos region of Texas (Figure 1.3.1). Six of the seven 

CHDN park units are located in the Northern Chihuahuan Subregion of the Chihuahuan Desert 

Ecoregion. The exception, AMIS, is situated primarily within the Tamaulipan Thornscrub (Mezquital) 

Ecoregion of southern Texas and northeastern Mexico, but it is also influenced by both the Chihuahuan 

Desert and Edwards Plateau ecoregions (Rich et al. 2004). Bailey and others (1994) provide another 

classification framework, which is standardized for the entire U.S. In this framework, land units at large 

scales (tens-of-thousands to millions of km2

) are identified according to domains, followed by divisions 

and then provinces. Bailey and others (1994) place CHDN park units within the Dry Domain, two 

different divisions and two different provinces. In the latter case, CAVE and GUMO would be considered 
6 

part of the Arizona-New Mexico Mountains Semi-Desert - Open Woodland - Coniferous Forest - Alpine 

Meadow Province. All other park units, including AMIS, would be considered part of the Chihuahuan 

Semi-Desert Province. Appendix D provides further discussion about land classification and reasons for 

emphasizing the use of the Chihuahuan Desert Ecoregion advanced by Pronatura Noreste and others 

(2004) for describing CHDN and its member units. 

Figure 1.3.1. Location of CHDN park units within the Chihuahuan Desert Ecoregion (map produced by CHDN; 

ecoregion boundary from Pronatura Noreste et al. 2004).
7 

1.3.2 Climate 

Precipitation and solar radiation are two dominant inputs that drive ecological processes in all desert 

ecosystems. Seasonality, spatial variability, and duration of precipitation act to create pulses of water 

input (Snyder and Tartowski 2006). When combined with the effects of evaporation, these pulses have a 

strong influence on the distribution of soil resources that determine the productivity and structure of other 

resources in the Chihuahuan Desert Ecoregion (Whitford 2002, Schlesinger et al. 2006). Solar radiation 

provides the initial energy that fuels primary production of vegetation and floral microbes in the aquatic 

systems and directly affects behavior and energy budgets of animals. Consequently, many plant and 

animal species have adapted special features to persist under conditions of low water availability and high 

solar radiation influx (Whitford 2002). In addition, chemical composition of rainfall and atmospheric 

nitrogen and carbon affect metabolic processes of soil microbes and plants (Schlesinger et al. 2006). 

Eolian (wind) processes also play a prominent role in this ecoregion by affecting soil transport, 

redistribution of nutrients, and convection, all of which affect evaporation of soil moisture and plant 

desiccation (Gillette and Pitchford 2004, Okin et al. 2006). 

The Chihuahuan Desert is one of three “warm” deserts of North America. The term warm refers more to 

the relatively milder temperatures during winter that allow precipitation to fall as rain, rather than snow 

(MacMahon 2000). The term desert is frequently applied to semi- or fully arid lands where (1) annual 

precipitation (P) is usually exceeded by evapotranspiration (ET) (e.g., P/ET <0.50), (2) annual 

precipitation typically is <400 mm (16 in), (3) interannual variability of that precipitation ranges from 20 

to 100%, and (4) ambient temperatures remain above freezing for more than six months each year 

(Whitford 2002). Climate within the Chihuahuan Desert Ecoregion is relatively uniform, with hot 

summers and cool or cold, dry winters (Schmidt 1979; Figure 1.3.2). This uniformity is due to the more 

or less equal distance of most areas of the desert from moisture sources (Gulf of Mexico and the Sea of 

Cortez), the uniformity of elevation of surrounding mountain masses, and the position of the desert on the 

continent, which results in little frontal precipitation. Consequently, a high percentage of Chihuahuan 

Desert precipitation falls in the form of monsoonal rains during the summer months (Figure 1.3.2; 

Appendix E). Although not as celebrated, as frequent, or as plentiful, winter rains can be a critical event 

for some species of plants and animals in the Chihuahuan Desert. Overall, this desert has more rainfall 

than other warm desert regions, with precipitation typically ranging from 150 to 500 mm (6–20 in) 

annually, averaging about 235 mm (10 in) (Schmidt 1979). In the Tamaulipan Thornscrub, rainfall tends 

to increase from west to east but, in general, that ecoregion receives larger amounts of more evenly 

distributed rainfall than does the Chihuahuan Desert. Some areas even approach a more humid, 

subtropical climate regime. 

Temperatures in the Northern Subregion of the Chihuahuan Desert Ecoregion rarely exceed 25°C. The 

warmest months are typically June through August (Figure 1.3.2; Appendix E). However, warm fall 

temperatures, especially following a wet monsoon season, can promote and extend the growing season for 

warm-season plants. 
8 

Figure 1.3.2. Walter climate diagram for CHDN park units (n = 8 stations; 2 from BIBE). Note that dry seasons occur 

when the precipitation line falls below the temperature line and wet seasons occur during months when the 

precipitation line is above the temperature line. The 95% confidence intervals for temperature indicate greater 

consistency among the park units than that for rainfall. Particularly variable are the summer rainfall amounts among 

the CHDN park units during this 30-yr period (1971–2000). A lack of winter months with temperatures less than 0°C 

(freezing point of water) is a primary reason why the Chihuahuan Desert is considered a warm desert. 

1.3.3 Elevation, landform, and soils 

Most of the Chihuahuan Desert Ecoregion lies between 900 and 1,500 m (approximately 3,000–5,000 ft) 

above sea level, although foothill areas and some isolated mountain ranges in the central portion of the 

ecoregion may rise to more than 3,000 m (about 10,000 ft). In the Tamaulipan Thornscrub Ecoregion, 

elevation increases northwesterly from sea level near the Gulf Coast to a base of about 300 m near the 

northern boundary of the ecoregion (Ricketts et al. 1999). 

In conjunction with climate, geologic and hydrologic properties and processes shape Chihuahuan Desert 

landforms. In turn, landforms create a template for a wide variety of ecological processes, including 

distribution, structure, and composition of resources (Wondzell et al. 1996, Monger and Bestelmeyer 

2006). At a broad scale, the Chihuahuan Desert Ecoregion is formed by a series of basins and ranges. At a 

finer scale, bajadas and alluvial fans become apparent and provide obvious examples of the fundamental 

effects of landforms on desert resources. The resulting soil structure on bajadas creates an ecological site 

that is often dominated by creosote (Whitford 2002). Even at small scales, minor variations in landform 

can modify the influence of solar radiation enough to facilitate thermal heterogeneity and different 

microclimates for plants and animals (Whitford 2002). Such orographic effects, caused by interactions 

between weather and landform, topography, and aspect, have a strong influence on the distribution of 

resources in both ecoregions (Pronatura Noreste et al. 2004, Monger and Bestelmeyer 2006). For 
9 

example, north-facing sides of deep, reticulated canyons often provide cooler, moister conditions, which 

in turn provide habitat for a mixture of riparian or non-xeric plant species and rare animal species, such as 

the Mexican spotted owl (Strix occidentalis lucida; Figure 1.3.3-1). Landforms can also affect the 

magnitude of natural disturbances. For example, slope and channel characteristics influence rates of water 

flow during precipitation (Simmers 2003). Given the same rate of rainfall, a steep, narrow arroyo with 

exposed bedrock will transport water faster and further than a gently sloped channel with a sandy bottom. 

The availability of soil moisture and nutrients is a primary factor limiting productivity in the Chihuahuan 

Desert (Whitford 2002, Snyder et al. 2006). Soil characteristics, such as stability, texture, structure, and 

associated biota, also directly influence plant composition, distribution, and growth (MacMahon and 

Wagner 1985, Whitford 1996, Huenneke and Schlesinger 2006). Direct and indirect effects on plant 

communities then influence the distribution and abundance of many vertebrate and invertebrate species 

(Whitford and Bestelmeyer 2006). Similarly, ecosystem resilience and function are related, in large part, 

to soil quality, integrity, and stability (Karlen et al. 1997, McAuliffe 2003). Loss and redistribution of soil 

resources in the Chihuahuan Desert Ecoregion can strongly affect system composition and function and 

ultimately lead to desertification (Schlesinger et al. 1990, Gillette and Pitchford 2004). 

Basin soils in the Northern Chihuahuan Desert Subregion are typically Aridisols. Predominant soil types 

include Torriorthents, Calciorthids, and Haplagids. Most are moderately deep to very deep, well-drained 

soils of loamy or clayey texture, characterized by a thermic temperature regime, an aridic moisture 

regime, and mixed or carbonatic mineralogy (USDA NRCS 2006). Soils along the Rio Grande in the Big 

Bend are hyperthermic. Approximately 80% of Chihuahuan Desert Ecoregion soils are derived from 

limestone beds. These soils sometimes have accumulations of calcium carbonate below the surface 

horizons that, when compacted, form a layer often referred to as caliche. Very shallow or compacted soil 

layers that are lime-rich can provide favorable substrates for cacti while creating less favorable 

environments for other plant species (Dick-Peddie 1993). Entisols are also found in some parts of this 

ecoregion. These soils are shallow, very poorly developed, and may consist primarily of sand and rock 

(USDA NRCS 2006). Mountain ranges also include Mollisols and Entisols. Mollisols include soils with 

loamy texture. Montane valleys may include very deep soils with well-developed O-horizons. Many of 

these soils have mesic temperature regimes (USDA NRCS 2006). Entisols include shallow soils over 

bedrock. Some Haplustolls (Brewster series) and Argiustolls (Mainstay series) may be found in colluvium 

underlain by igneous rock on hills and mountains. 

A notable example of soil effects on plant communities can be seen at WHSA. Here, a substantial amount 

of soil is created from water-leached dolomite, which collects, evaporates, and forms gypsum crystals in a 

large playa lake bed (Kiver and Harris 1999). These crystals eventually weather and are then transported 

by wind away from the lakeshore to form gypsum dunes (Langford 2003). The chemical composition, 

coarse structure, and instability of these soils often preclude development of diverse plant communities. 

Plants that do manage to thrive in these soils have a high tolerance of gypsum (Dick-Peddie 1993), and 

many of the invertebrate and vertebrate species have adapted a pale or white coloration that matches the 

soil color (Figure 1.3.3-2, Rosenblum 2006). Although some biota may be limited by gypsum soils, the 

shaping of unique forms tolerant of this local condition ultimately increases regional biological diversity.
10 

Figure 1.3.3-1. Mexican spotted owl roosting in a 

chinquapin oak in a canyon in Guadalupe Mountains 

National Park. Photo by Timothy C. Mullet. 

Figure 1.3.3-2. Little white whiptail lizard adapted to 

dunes. Photo by James Borgmeyer.

1.3.4 Water and hydrology 

Water is a precious resource in any ecoregion, but all life forms in the Chihuahuan Desert Ecosystem are 

particularly dependent on the quantity and quality of water due to its relative scarcity and the poor quality 

of desert soils. The Northern Chihuahuan Desert Subregion is bisected by three predominant rivers, the 

Rio Grande (or Río Bravo del Norte), Conchos, and Pecos. In addition, the Rio Grande, Pecos, and Devils 

River empty into a large, internationally shared reservoir at AMIS, the southeastern edge of this 

subregion. 

These waters are influenced by a number of factors, including interactions among climate, hydrology, 

watershed conditions (e.g., geology, landforms, and soils), vegetation, impoundments, and natural 

disturbance regimes. The quality of these waters is a priority management concern throughout the 

subregion. Water quality information has been compiled for CHDN park water bodies (Porter et al. 2009). 

Free-flowing and standing water also produce a diverse array of freshwater habitats in the two ecoregions. 

These include large rivers, numerous seeps and springs, and smaller perennial and ephemeral streams 

(Table 1.3.4). 

Large gains in streamflow (100–400 ft3

/s) along the lower segments of RIGR presumably are associated 

with springs discharging from the Edwards-Trinity (Plateau) aquifer. The Pecos River is less influenced 

by groundwater flows, but drawdown of the underground water will likely affect the hydrology of the 

majority of water bodies and smaller springs in the subregion. Combinations of periodic drought, a 

natural and frequent disturbance factor in the Chihuahuan Desert Ecoregion, combined with intensive use 

of groundwater for agriculture, has caused serious environmental degradation and loss of habitat and 

endemic species at Cuatrociénegas, in Coahuila, Mexico (Hendrickson et al. 2008). 
11 

Table 1.3.4. Aquatic habitat types of the Chihuahuan 

Desert (adopted from Dinerstein et al. 2000). 

Type Sub-type(s) 

I. Warm springs A. high salinity 

B. low salinity 

II. Cool springs A. high salinity 

B. low salinity 

III. Large rivers & floodplains 

IV. Perennial streams A. high gradient 

B. medium gradient 

C. low gradient 

V. Ephemeral streams A. high gradient 

B. medium gradient 

C. low gradient 

VI. Lagunas A. permanent 

B. temporary 

VII. Cienegas 

VIII. Subterranean habitats 

1.3.5 Flora and plant communities 

As recently as 9,000 years ago, the Northern Chihuahuan Desert Subregion was much more mesic in 

climate and dominated by coniferous woodland, typically piñon pine (Pinus spp.) and juniper (Juniperus 

spp.; Allen et al. 1998, Van Devender 1990). Miller (1974) suggested that increasing aridity of the 

Chihuahuan Desert resulted in isolation, differentiation, and extinction that led to the unique biota 

observed today. The Sierra Madre Oriental, which forms the eastern boundary of the Chihuahuan Desert, 

is one of the oldest and richest centers of plant evolution on the North American continent. The northern 

Chihuahuan Desert, which lies on the Mexican Plateau, is essentially a broad physiographic expansion of 

the Sierra Madre Oriental (Johnson 1974). 

Conservation organizations, such as the World Wildlife Fund, consider the Chihuahuan Desert Ecoregion 

one of the most diverse deserts in the world and a critical reservoir for conserving biodiversity (Olson and 

Dinerstein 1998). At least 1,000 endemic plant taxa occur in the Chihuahuan Desert, an astonishing 

richness of biodiversity (Johnson 1974). This high desert area is a center for endemism of yuccas and 

cacti (Hernández and Bárcenas 1995). Of the 1,500 known species of cacti, 350 occur in the Chihuahuan 

Desert. Four other plant families (grasses, euphorbs, asters, and legumes) also show high levels of 

endemism across the many basins of the desert (Dinerstein et al. 2000). The diversity of the Tamaulipan 

Thornscrub is not as high as that of the Chihuahuan Desert, but it still supports more than 600 species of 

plants and animals. The region is particularly rich in tree species, including two endemics, and birds 

(Ricketts et al. 1999). 

Plant assemblages and communities can be described in many ways. In this report, we describe plant 

assemblages using vegetation habitat types (Table 1.3.5, Appendix D). Habitat types and subtypes of this 

ecosystem include Larrea Desert Scrub, Mixed Desert Scrub, Chihuahuan Sandy Plains Semi-Desert 

Grassland, Chihuahuan-Sonoran Desert Bottomland and Swale Grassland, Chihuahuan Gypsophilous 

Grassland and Steppe, Chihuahuan Succulent Desert Scrub, Chihuahuan Mixed Desert and Thorn Scrub, 

Yucca Woodland, Gypsophilous Scrub, Desert Wash/Riparian Woodland and Shrubland, Desert Riparian 
12 

Woodland and Shrubland, Desert Riparian Mesquite Bosque, Lowland Riparian Marshland, and Playa. 

Two assemblages of Tamaulipan Thornscrub Habitat Type, South Texas Plains Scrubland and Edwards 

Plateau Scrubland, are found bordering the Reservoir Ecosystem of AMIS. These habitat types are 

described further, along with the names of common plant species found in each type, in Appendix D. 

Table 1.3.5. Terrestrial habitat types of the Chihuahuan Desert Ecoregion. 

I. Desert Scrub and Woodlands II. Grasslands III. Montane Chaparral and Montane 

Woodlands 

 A. Larrea Desert Scrub A. Grama Grassland A. Montane Chaparral 

 B. Mixed Desert Scrub B. Sacaton Grassland B. Juniper-Piñon Woodland 

 C. Yucca Woodland C. Tobosa Grassland C. Pine-Oak Woodland 

 D. Izotal (Dasylirion-Yucca-Agave) D. Gypsum Grassland D. Mixed-Conifer Forest 

 E. Prosopis Scrub E. Lowland Riparian Marshland E. Montane Deciduous Woodland 

 F. Gypsophilous Scrub 

 G. Lowland Riparian Woodland 

 H. Playa 

Adopted from Dinerstein and others (2000); see Appendix D for detailed descriptions of these habitat types. 

Diversity within (alpha diversity) and among (beta diversity) Chihuahuan Desert habitat types is 

influenced by a number of factors, including landform, soil condition, climate, elevation, topography, 

land use, and faunal interactions (Guo 1998, Peters and Gibbens 2006). During the last century, woody 

shrubs have intruded and expanded into areas of this ecosystem once dominated by or occupied by 

grasses (Peters and Gibbens 2006). The causes of this shift are equally diverse and complex, involving 

historical fauna and land use, human and animal forms of plant seed dispersal, excessive herbivory, 

extended drought, increased atmospheric carbon dioxide, fire, redistribution and heterogeneity of soil 

resources, and physiological adaptations of plants (Cole and Monger 1994, Fredrickson et al. 2006, 

Housman et al. 2006, Peters et al. 2006, Peters and Havstad 2006). 

Currently, desert shrublands comprise half (50%) of Northern Chihuahuan Subregion landscapes. Desert 

grasslands, covering approximately 25% of the subregion, are often mosaics of grass and shrub. Mixedconifer forests and woodlands comprise approximately 10% of the subregion. Consequently, the 

Chihuahuan Desert is now considered synonymous with shrublands and its boundaries are determined by 

the contiguous distributions of creosote bush (Larrea tridentata) and tarbush (Flourensia cernua) (DickPeddie 1993). This change has increased the significance of remaining desert grasslands, particularly 

those once dominated by black grama (Bouteloua eriopoda). Lechuguilla is also considered a signature 

plant of the Northern Chihuahuan Subregion (Figure 1.3.5). 

In the Tamaulipan Mezquital, trees such as acacia (Acacia spp.) and mesquite (Prosopsis glandulosa) 

dominate, along with other shrub species and some grasslands. Some grasslands occur within this 

ecoregion. The most common grasses found include curly mesquite grass (Hilaria belangeri), hooded 

finger grass (Chloris cucullata), grama (Bouteloua spp.), and muhly (Muhlenbergia spp). 
13 

1.3.6 Fauna 

The Chihuahuan Desert supports more than 120 species of mammals, 450 species of birds, 110 species of 

fish, and more than 170 species of amphibians and reptiles. Chihuahuan Desert function depends on its 

high invertebrate diversity, which is a reflection of numerous plant communities. Subterranean termites of 

the order Isoptera consume dead plant material and animal dung and serve as keystone invertebrates 

within the desert grasslands. Fifty percent of all photosynthetically fixed carbon in desert grasslands is 

consumed by these termites (Whitford et al. 1995). Specialized freshwater assemblages of invertebrates 

associated with playas, such as clam shrimp (Eulimnadia texana), water fleas (Moina wierejskii), and 

fairy shrimp (Streptochephalus texanus), provide food for migrating waterfowl. Other invertebrates 

associated with soil, such as nanorchestid and tydeid soil mites, are essential for nutrient cycling in the 

dry climate. Monarch butterflies rely on the riparian vegetation to rest during their migration (Ayala et al. 

1993). 

The larger Río Grande system is home to native minnow, sucker, catfish, killifish, and sunfish species: 

two species of gar (Lepisosteus oculatus, L. osseus); and a rare sturgeon (Scaphirhynchus platorhynchus). 

Rivers draining into the interior, such as the Río Nazas, located north of Durango, Mexico, contain unique 

assemblages of minnows, suckers, and pupfish. Isolated basins, such as the Tularosa, in New Mexico, and 

Cuatrociénegas in Coahuila, have given rise to numerous endemic fish species, including several pupfish 

(Cyprinodon spp.), cichlids (Cichlasoma spp.), and poeciliids (Gambusia marshi and G. longispinis) 

(Miller 1974, Minckley 1974). The primary distinguishing feature of the Chihuahuan Desert freshwater 

biota is not the number of species, but the high degree of globally outstanding local endemism (Dinerstein 

et al. 2000). 

At least 18 species of reptiles and amphibians are endemic to the Chihuahuan Desert, including the bolson 

tortoise (Gopherus flavomarginatus) (Ricketts et al. 1999), black softshell turtle (Trionyx ater), 

Chihuahuan fringe-toed lizard (Uma exsul), and the little white whiptail (Aspidoscelis gypsi) (see Figure 

1.3.3-2). The habitat ranges of several lizards are centered in the Chihuahuan Desert. Representative 

snakes include the Trans-Pecos rat snake (Elaphe subocularis), Texas blackheaded snake, (Tantilla 

atriceps), and western coachwhip (Masticophis flagellum testaceus). 

Figure 1.3.5. Dense stand of 

lechuguilla and sotol at Big Bend 

National Park. NPS Photo 
14 

The Chihuahuan Desert is one of few ecoregions where grizzly bears, wolves, and jaguars once were 

found at the same locality. Other wide-ranging mammals found in this region include pronghorn antelope 

(Antilocapra americana), collared peccary, or javelina (Dicotyles tajacu), and mule deer (Odocoileus 

hemionus). Unfortunately, the list of mammals includes non-native ungulates, as well (Appendix C). For 

example, Barbary sheep, or aoudad (Ammotragus lervia) and oryx, or gemsbok (Oryx gazelle) occur in 

the Northern Chihuahuan Subregion. Heteromyid rodents are considered keystone species and mesocarnivores; ringtail (Brassariscus astutus), skunks, and fox species are common. This desert region also is 

well-known for its high diversity of bats. The largest remaining black-tailed prairie dog (Cynomys 

ludovicianus) towns on the continent, and the only populations of the endemic Mexican prairie dog 

(Cynomys mexicanus), occur in the Chihuahuan Desert. 

Neotropical migratory birds use riparian corridors along the Pecos River and the Rio Grande. Chihuahuan 

Desert grasslands serve as wintering grounds for a large proportion of North American Great Plains birds, 

including a number of significantly declining species, such as mountain plover (Charadrius montanus), 

ferruginous hawk (Buteo regalis), and Baird’s sparrow (Ammodramus bairdii). 

1.3.7 Ecosystems of CHDN park units 

The seven park units of the CHDN represent the most significant natural, cultural, and recreational values 

in the Chihuahuan Desert. Most CHDN park units were established for conservation and preservation of 

significant natural and geologic resources (e.g., the caverns of Carlsbad Caverns NP). The exception is 

FODA, which was established primarily for cultural reasons, but also contains significant natural 

resources. Here we first present a brief summary of the biophysical properties discussed above as they 

apply to each of the CHDN park units (Table 1.3.7-1). We then describe the types and spatial distribution 

of ecosystems found in each CHDN park unit. Knowledge of ecosystem properties and function is the 

cornerstone of natural resource management and a requisite to designing a reliable monitoring program. 

Additional information about each CHDN unit, including resource and management concerns, can be 

found in Appendix C. Information about functional relationships among ecosystem components is 

presented in Chapter 2. 

We identified six ecosystems for describing CHDN park units: (1) Desert (<1,370 m/4,500 ft elevation), 

(2) Foothill (1,370–1,981 m/4,500–6,500 ft elevation), (3) Montane (>1,981 m/6,500 ft elevation), (4) 

Reservoir, (5) River (applied to the three major rivers; the smaller wetland types are addressed within 

terrestrial ecosystems), and (6) Unique (Table 1.3.7-2). These ecosystems were designated irrespective of 

vegetation type. The Unique category includes two subsystems, caves and dune fields. Caves of Carlsbad 

Caverns NP may be more appropriately considered a subsystem of the Foothill and Desert Ecosystems, 

and the Dune Fields of WHSA and GUMO a subsystem of the Desert Ecosystem. However, our 

designation of these systems as unique was done in part to allow for the identification of vital signs 

unique to these specialized systems. Our classification embodies two fundamental concepts: (1) that soil, 

topography, and parent material form a soil-geomorphic template that can influence hydrologic flow and 

biotic change, and (2) that abiotic factors, such as precipitation and temperature, which also influence 

hydrologic properties and the composition and structure of biotic communities, correspond to topography 

(Monger and Bestelmeyer 2006). 
15 

To summarize the spatial extent and distribution of CHDN ecosystems, we estimated the area associated 

with each ecosystem by NPS unit (Table 1.3.7-2). Areas for the non-specialized terrestrial systems and 

Amistad Reservoir were estimated from elevation bands and a comprehensive digital elevation model 

(60-m resolution) developed for the Chihuahuan Desert Ecoregion (Monger et al. 2005). Based on 

elevations provided by AMIS staff, area for Amistad Reservoir was estimated from the elevation 

associated with conservation water surface elevation (340 m [1117 ft]). Area for the River Ecosystem was 

based on a product of an average river width (0.185 km [0.12 mi]; n = 30 segments of the Rio Grande) 

and total river length in each NPS unit. The spatial extent and distribution of each of these ecosystems 

throughout the CHDN are shown in Figure 1.3.7. The administrating park units provided area of dune 

fields and linear distance of caves. 
16 

Table 1.3.7-1. Biophysical summary of Chihuahuan Desert Network parks. 

Species richness5

Number of species 

(Species/km2)

Park unit 

Precip. 

(mm)1 Temperature (°C)2 Elevation Range (m) 

Aquatic 

habitats3 Terrestrial habitats4

Plants Vertebrates

AMIS 475 

(0–364) 

20.6 

(0–39.6) 

282–364 IIB, III, IVC, 

VIII 

IB, IE, IG 691 

(2.98) 

323 (0.39) 

BIBE 245/479 

(0–268) 

16.5/21.9 

(-2.0–43.8) 

548–2,387 IB, IIB, III, 

IVC, VABC 

IA, IB,ID, IE,IG, 

IIA, IIB, IIC, IIE, 

IIIA, IIIB, IIIC 

1,321 

(0.40) 

598 (0.18) 

CAVE 406 

(0–423) 

16.5 

(-3.7–36.7) 

1,096–1,992 IIB, VB, VIII IA, IB, IC, ID, IE, 

IIB, IIE, IIIB 

929 

(4.90) 

483 (2.55) 

FODA 397 

(0–226) 

15.9 

(-4.7–36.7) 

1,487–1,622 VC IB, IIA, IIIA 368 

(191.67) 

165 (85.94) 

GUMO 

(near HQ) 

392 

(0–197) 

(-4.3–33.7) 1,105–2,667 IIB, IVA, IVC, 

VA, VB, VC, 

VIB 

IA, IB, ID,IE, IF, 

IG, IH, IIA,IIB, IID 

IIIA, IIIC, IIID, IIIE 

985 

(2.82) 

366 (1.05) 

RIGR 367 

(0–217) 

20.3 

(-4.1–39.9) 

360–616 IB, III, IB, ID, IE, IG, 

IIIA, IIIB ----- ----- 

WHSA 258 

(0–245) 

15.0 

(-9.9–38.7) 

1,185–1,290 VC IA, IB, IF, IH, IIB, 

IID 

265 

(0.46) 

254 (0.44) 

1

Thirty-year, 1971–2000, mean values for total annual precipitation and (monthly minimums–maximums). Given its expansive area, 

two stations from BIBE are reported: Castolon andChisos Basin. 

2 Thirty-year, 1971–2000, mean values for the annual temperature and (monthly minimums–maximums). Given its expansive area, 

two stations from BIBE are reported: Castolon and Chisos Basin. 

3

See Table 1.3.4 for description of aquatic habitat type identifiers. 

4

 See Table 1.3.5 for description of terrestrial habitat identifiers. See Appendix D for detailed habitat descriptions. 

5

 See Table 1.3 for park areas and C.7-1 for number of species used to generate species richness/km2. 

These area values indicated the vast extent (77%) of the Desert Ecosystem in the CHDN, occurring in five 

of seven NPS units (Table 1.3.7-2). However, the areas also indicated that effort and resources for 

monitoring health and function of these ecosystems should not be allocated strictly by extent or coverage 

of a particular system. Such a strategy would ignore the smaller River Ecosystem, which is ecologically 

and economically significant to the northern Chihuahuan Desert and its inhabitants (Ward and Booker 

2003). Figures 1.3.7B and 1.3.7E show the variety of ecosystems occurring within BIBE and GUMO. 

These two park units also have the greatest number of plant and animal species listed in Table 1.3.7-1. 
17 

Table 1.3.7-2. Classification, area, and distribution of ecosystems within CHDN national parks. Classifications werelevation and landform. 

Area (km2

Ecosystem Description 

AMIS 

BIBE 

CAVE 

FODA 

GUMO 

Desert Arid terrestrial and non-extensive aquatic systems that occur at lower elevations, 

generally <1,370 m (<4,500 ft). Major subsystem or habitat types include Chihuahuan Desert Grasslands, Chihuahuan Desert Shrublands, Tamaulipan Desert Shrubland, Playa/Salt Flats, Perennial Streams, Springs/Seeps, and Intermittent/Ephemeral Streams plus associated vegetation (e.g., riparian). 

47 3,041 60 0 119a 

Foothill Arid/Semi-arid terrestrial and non-extensive aquatic systems that occur at mid-level 

elevations, 1,370–1,981 m (4,500 to 6,500 ft). Major subsystem or habitat types include Woodlands, Chaparral, Perennial Streams, Springs/Seeps, and Intermittent/Ephemeral Streams plus associated vegetation (e.g., riparian). 

0 173 129 2 124 

Montane Montane terrestrial and non-extensive aquatic systems that occur at upper 

elevations, >1,981 m (>6,500 ft). Major subsystem or habitat types include Montane Forest, Perennial Steams, Springs/Seeps, and Intermittent/Ephemeral Streams plus associated vegetation (e.g., riparian). 

0 17 0 0 99 

Reservoir Aquatic system associated with Lake Amistad, a reservoir created by damming the 

Rio Grande below the confluence of the Devils and Pecos Rivers. 

182 0000

River Large river and associated aquatic systems. Includes Rio Grande and primary river 

confluences in or proximal to park units (e.g., Devils and Pecos Rivers). Area values 

only for the in-unit river lengths. 

3b 11 0 0 0 

Unique Ecosystems that are extensive and/or different enough that components and 

processes defined for the other described systems are not adequate for defining function of these unique systems. These would include primarily Gypsum (or other) Dune Systems and Subterranean Cave Systems. 

0 0 256c 0 8 

Total CHDN 

a Excluding the dune systems, which, by elevation, also could be considered in the Desert Ecosystem. b Based on number of free-flowing river kilometers, not influenced by the reservoir. Numbers provided by Amistad NRA. c Linear kilometers surveyed for 113 caves in Carlsbad Caverns National Park. No area estimate calculated. 
18 

Figure 1.3.7A–F. Ecosystems of Chihuahuan Desert Network parks. 

B. Big Bend NP

E. Guadalupe Mountains NP F. White Sands NM

C. Carlsbad Caverns NP D. Fort Davis NHS

A. Amistad NRA

Desert ecosystem

Foothill ecosystem

Montane ecosystem

Dune ecosystem

Rivers and streams

Reservoirs and lakes
19 

1.4 Park Natural Resources Issues and Management Concerns 

CHDN parks share similar natural resources, threats, issues, and management priorities. In order to 

narrow the focus, ensure relevance to several network parks, and increase efficiencies in the planning 

process, priorities were established among focal resources and resource concerns. Network staff used 

many tools to identify important management issues and other common priorities, including reviews of 

park management plans (i.e., General Management Plans, Resource Management Plans), reviews of state 

conservation strategies, interviews with park staff and outside cooperators, park-based vital signs scoping 

workshops, Technical Committee meetings, and direct observation. The following section provides a 

summary of methods that helped the CHDN with vital signs planning and ecological model development. 

1.4.1 Issues identified in park interviews and network scoping 

Personal interviews with superintendents, division chiefs, park natural resource staff, other park staff, and 

other NPS staff who provide services to multiple parks (e.g., Exotic Plant Management Team program 

manager, regional fire ecologist) were conducted during the fall of 2004 (Appendix G). The responses 

compiled from this questionnaire were kept anonymous, and served to identify initial management issues, 

threats to park resources, and areas in need of monitoring. These responses also provided a starting point 

for discussions at park-based vital signs scoping workshops held from December 2004 through April 

2005 to create park-specific lists of issues, threats, and potential vital signs (Appendix G). High-priority 

issues identified in this early stage included air quality degradation; impacts of climate change to water 

quantity and plant communities; impacts of soil erosion to natural plant communities; impacts of 

invasive/non-native plant species and groundwater withdrawal on persistence of springs and seeps; 

impacts to water quality; impacts to riparian and grassland bird communities; and understanding landcover, land-pattern, and land-use changes over time and their impacts to habitat quality, connectivity, and 

fragmentation. Summary results are provided in Table 1.4.1. 

Table 1.4.1. Relative importance of Chihuahuan Desert Network ecosystem 

stressors (from the CHDN park-level vital signs scoping workshops, 2004–2005). 

Stressor 

AMIS BIBE CAVE FODA GUMO WHSA Overall 

Groundwater Quantity Depletion L H H M H H H 

Invasive/Non-native Plant Species M H M L H H H 

Water Quality Degradation H H M L H L H/M 

Climate Change L H M M M M M 

Altered Disturbance Regimes M H M M H L M 

Historic/Contemporary Livestock Grazing H H L M M L M 

Air Quality Degradation L H M L H M M 

Land-use Change M H M - M M M 

Recreation M M M L M - M 

Soil Alteration - H L L M M M 

Resource Extraction L M H L H L M/L 

L = low importance; M = moderate importance; H = high importance 
20 

1.4.2 General management plans and resource stewardship strategies 

The CHDN parks have either recently completed their General Management Plans (GMP) (e.g., BIBE 

completed in 2004, GUMO completed 2008) or have not yet begun the process of updating their GMPs 

(e.g., CAVE, WHSA). This process takes 3–5 years, or longer, to define how the park will be managed 

for the following 15–20 years. Each park describes its desired future conditions, then develops a plan for 

achieving those conditions through management of visitor use, facilities, and resource protection through 

a variety of alternatives. Public comment and scoping helps ensure the park’s vision is consistent with the 

vision of its users and, through an iterative process, the GMP is developed. 

Some parks underwent the GMP process during the development and/or finalization of the CHDN vital 

signs monitoring plan. In those cases, it was useful for park managers to be thinking about what might be 

occurring in their parks two decades in the future as they considered how park resources may be affected 

over the long term. Using the information collected during the vital signs planning process and 

implementation should assist park managers not only in determining the ecosystem health of their parks, 

but also in deciding how to manage toward the desired future conditions stated within their GMPs. 

1.4.3 State comprehensive wildlife conservation strategy 

As the number of species listed under the Endangered Species Act has steadily increased, along with the 

costs involved with saving imperiled species, it has become clear that a more comprehensive approach to 

wildlife conservation is necessary. The U.S. Congress helped to address this need by creating the State 

Wildlife Grants Program in 2002. Under this national effort, with all U.S. states and territories 

participating, each entity created a long-range strategy for managing all fish and wildlife under its 

jurisdiction. These strategies were submitted to the U.S. Fish and Wildlife Service by October 1, 2005. 

The objectives of the program are to identify species (and their habitats) of greatest conservation need and 

to develop and implement high-priority conservation actions to abate problems for those species and 

habitats. These steps will save millions of tax dollars by preventing declines before species become 

imperiled. The State Wildlife Grants Program encourages partnerships and cooperation through a fundmatching requirement. 

The states of New Mexico and Texas both completed their conservation strategies for the program 

(NMGF 2005; Bender et al. 2005), and the National Park Service and the CHDN are participating in 

implementation strategy meetings for these plans. Materials from the strategy documents were used in 

developing habitat descriptions to affirm the linkages in CHDN’s ecosystem characterization models. The 

CHDN hopes to actively collaborate with these efforts so that regional trends may be better evaluated in 

the future. 

1.4.4 Vital signs monitoring in Mexico 

Taking advantage of the synergy that was generated from a sister-park meeting held at Grand Canyon 

National Park, Arizona, in February 2008, and through funding from a Sister Parks Program grant to 

WHSA (summer 2008), the National Commission of Protected Natural Areas (CONANP); WHSA and its 

Sister Park, Área de Protección de Flora y Fauna Cuatrociénegas (CC); and the CHDN began a 

partnership to explore monitoring of vital signs common to both parks. In a three-day workshop held in 

early September 2008, representatives from two Mexican parks; the northeastern regional director for 

CONANP; staff from WHSA, CHDN, and the Western National Parks Association; and university 

researchers met to discuss similar park management issues, assist CC in developing interpretive and other 

educational programs that promote community and visitor support for resource conservation and 

protection, and share components of the CHDN I&M program (i.e., utilizing protocols, research and 

inventory methodologies) with CC. CONANP expressed interest in adopting the protocols of CHDN and 

other I&M networks, systemwide. 
21 

1.5 Designing an Integrated Monitoring Program for the Chihuahuan 

Desert Network 

Each network is required to design an integrated monitoring program that addresses the five broad, 

servicewide monitoring goals listed in Section 1.2.1, and is tailored to the high-priority monitoring needs 

and partnership opportunities for the parks in that network. Working from the servicewide goals, the 

CHDN has developed a set of monitoring objectives for each of its high-priority vital signs, grouped into 

the following conceptual categories (Figure 1.5; Woodley 1993): 

1. Threat-specific Monitoring. Conducted when sufficient understanding exists between potential 

effects and responses by park resources (known effects), monitoring of system drivers, stressors, 

and affected park resources. 

2. Focal Resource Monitoring. Monitors a set of focal resources (including ecological processes) to 

address both known and unknown effects of system drivers and stressors on park resources. 

3. Ecosystem Status Monitoring. Monitors key properties and processes of ecosystem status and 

integrity to improve long-term understanding and potential early warning of undesirable changes 

in park resources. 

Figure 1.5. The conceptual framework for categorizing CHDN vital signs (adapted from Woodley 1993). 
22 

These categories provide a useful framework for organizing not only the selected vital signs, but also the 

thinking by which these vital signs were selected. The intent has been to ensure that at least some vital 

signs are selected from each category to ensure program integration, so that when taken together, the 

CHDN program whole is greater than the sum of its parts. This approach is necessary because practical 

constraints, such as budgets and staff size, prevent the selection of all important vital signs. Selecting vital 

signs from each of these categories helps ensure a balanced, integrated program that can address the status 

and long-term trends of ecological phenomena across a range of temporal and spatial scales, and for 

which effects are both known and unknown. 

1.5.1 CHDN approach to vital signs monitoring 

The basic approach to designing a monitoring program should follow five steps: 

1. Define the purpose and scope of the monitoring program. 

2. Compile and summarize existing data and understanding of park ecosystems and resource 

management issues. 

3. Develop conceptual models of relevant ecosystem components. 

4. Select indicators and specific monitoring objectives for each. 

5. Determine the appropriate sampling design and sampling protocols. 

These steps were incorporated into a three-phase planning and design process established for the CHDN 

monitoring program. Phase 1 of the process involved defining goals and objectives; beginning the process 

of identifying, evaluating, and synthesizing existing data; developing draft conceptual models; and 

completing other background work as a prelude to the selection of ecological indicators (NPS 2006b). 

Much of this background information is documented in this chapter and appendix reports (Appendices C–

H). Conceptual models are discussed in Chapter 2. 

Phase 2 of the planning and design effort involved prioritizing and selecting a core set of vital signs and 

developing specific monitoring objectives for each vital sign that will be included in the network’s initial 

monitoring program. The process is documented in Chapter 3 and Appendix I. 

Phase 3 entailed the detailed design work needed to implement monitoring, including outlining strategies 

for vital signs implementation and relationships with existing programs, outlining sampling design issues 

(Chapter 4), and developing specific monitoring objectives for the 10 protocols CHDN will be 

implementing (see Chapter 5, Table 5.1 and Appendix J). These monitoring objectives will be refined as 

protocol development progresses. Phase 3 also included a plan for data management (Chapter 6 and 

Appendix K); details on the type of analyses and content of various products of the monitoring effort, 

such as reports and websites (Chapter 7); and the administrative structure (Chapter 8). Chapter 9 outlines 

the anticipated schedule of protocol development and monitoring activities planned for the five years 

following plan approval. The budget is shown in Chapter 10. 

The CHDN recognizes the NPS I&M program as a unique opportunity to advance understanding of the 

ecosystems that encompass CHDN parks. The CHDN is committed to being an active partner with state 

and federal agencies, academic institutions, and other organizations involved with monitoring in the 

Chihuahuan Desert, as well as actively pursuing coordination and partnerships with Mexico. The network 

also is committed to establishing the foundation for a monitoring program that will last in perpetuity. 
23 

1.6 Summary of Current Monitoring Within and Surrounding the 

Network 

An understanding of current and past monitoring activities in and around network parks is an important 

foundation for development of the CHDN vital signs monitoring program. Such information allows the 

network to identify where monitoring is adequate, might need to be expanded (or abandoned), or where 

additional inventory, monitoring, or protocol development is needed. 

Thorough analysis of current and past monitoring projects and data (Table 1.6) could serve as the basis 

for long-term monitoring in parks related to high-priority CHDN vital signs. However, the small staff of 

CHDN parks has limited the amount of natural resource monitoring currently occurring in those parks. 

Several parks participate in annual breeding bird surveys or National Audubon Society Christmas bird 

counts, but few conduct any formal resource monitoring and, with the exception of monitoring for some 

threatened and endangered bird species, none of these monitoring projects is conducted with peerreviewed protocols that include a statistically sound sampling strategy. 

Table 1.6. Record of historic (H, >5 years ago) or current (C) monitoring data for CHDN parks. 

CHDN parks Category 

AMIS BIBE CAVE FODA GUMO WHSA 

Air quality-Ozone C C C 

Air quality-Wet and dry deposition C C 

Air quality-Visibility and particulates C C 

Climate-Basic meteorology C C C C C C 

Cave resources1

 C 

Groundwater dynamics H H H H C C 

Surface water dynamics C C H 

Surface water quality C C H C 

Springs/seeps C H H 

Invasive/Non-native plants C C C 

Vegetation change H,C H H 

Bird communities H2

 C3 C3,4 C3 

Fish communities C C 

Species-at-risk C5

 H6,C7 H8 C9 H10 

Fire and fuel dynamics H,C C H,C 

1

Cave resources (water, microbial, climate) 

2

MAP Station (2000–2004) 

3

Christmas Bird Counts 

4

Cave swallows (1980–2009)

5

Interior least terns (1986–2009) 

6

Peregrine falcon (1976–2003) 

7

Black-capped vireo (1987–2009); Chiso’s hedgehog cactus (1996–2009) 

8

Bell’s Vireo 

9

Mexican spotted owl 

10White Sands pupfish 
24 

The lack of past long-term monitoring activities in network parks serves to reinforce the importance of the 

I&M program to this group of parks. Natural resource information upon which resource managers can 

base sound decisions upon is extremely limited. 

1.6.1 Air quality monitoring 

Air pollution damages resources and values that national parks are mandated to protect. Under the Clean 

Air Act and GPRA mandate, managers of Class I parks have a special responsibility to monitor and 

protect air quality and related resources from the adverse effects of air pollution, and to provide 

recommendations to protect park natural and cultural resources. At the network level, monitoring air 

quality conditions and understanding their interactions with physical and biological components of the 

ecosystem is vitally important to effectively evaluating the effects of these hazards on ecosystem health. 

In the CHDN, climate and air quality data are monitored at a variety of stations in six park units (Table 

1.6.1, Appendices E and H). BIBE, CAVE, and GUMO are Class I air quality areas, receiving the highest 

protection under the Clean Air Act. The other park units are Class II air quality areas, which also receive 

protection under the Act. Air quality issues of concern in the CHDN include atmospheric deposition 

effects and visibility impairment from fine particle haze. Atmospheric nitrogen deposition can cause 

changes in soil that affect soil microorganisms, plants, and trees. Excess nitrogen can cause changes in 

plant community structure and diversity, with native species being replaced by invasive and exotic 

species. Nitrogen and sulfur deposition can also have an acidifying effect on soils and water, decreasing 

buffering capacity and eventually reducing pH. Research has found a rapid, major decrease in soil pH in 

BIBE grasslands. Studies were initiated in 2003 to assess the impacts of atmospheric nitrogen deposition 

and climate change on desert ecosystems in the park. 

The NPS has summarized five-year averages of annual ozone values from 1995 to 1999 (NPS-ARD 

2004). Two CHDN parks (AMIS and CAVE) are considered at moderate risk from ozone. These two 

parks exceeded the ozone standard with values of 0.8 ppm, levels that could damage foliage. Even though 

AMIS is considered to be at moderate risk, no ozone-sensitive plant species have been identified there. 

One ozone-sensitive plant species (skunkbush, Rhus trilobata) has been identified at CAVE, but the level 

of soil moisture significantly constrains the uptake of ozone and reduces the likelihood of foliar injury. 

The other parks in the network have a low-risk rating, due to lower ozone levels, though ozone-sensitive 

plant species do occur at other network parks. These plants include ponderosa pine (Pinus ponderosa) and 

skunkbush at BIBE and GUMO, and Southwestern chokecherry (Prunus serotina) and skunkbush at 

BIBE, FODA, and GUMO (NPS-ARD 2004). 

Types of monitoring at BIBE and GUMO include ozone monitoring through the NPS Gaseous Pollutant 

Monitoring Network, wet deposition monitoring of atmospheric pollutants by the National Atmospheric 

Deposition Program (NADP), dry deposition monitoring of atmospheric pollutants by the Clean Air 

Status and Trends Network (CASTNet), and visibility monitoring through the Interagency Monitoring of 

Protected Visual Environments (IMPROVE) Program. CAVE has a temporary station set up to monitor 

ozone only. All of the parks, except RIGR, have one or more climate monitoring stations (see Appendix 

E). 

Air-quality-related values (AQRV) are resources that may be adversely affected by a change in air 

quality. The resource can include visibility of a specific scenic, cultural, physical, biological, ecological, 

or recreational resource. Table 1.6.1 identifies natural resource AQRVs of each CHDN park. As new 

information is developed for the network, it will be added to the NPS Air Resources Division’s Air 

Resources Information System website, http://www2.nature.nps.gov/air/permits/aris/networks/index.cfm.
25 

Table 1.6.1. Air quality-related values (AQRV) of Chihuahuan Desert Network parks. Park Visibility1 Vegetation2 Surface Waters3 Soils4 Fish and wildlife5 NighAMIS   Unknown Unknown  BIBE      

CAVE    Some soils may be sensitive to eutrophication  

FODA   No Unknown  

GUMO      

RIGR  Unknown Unknown Unknown * 

WHSA     Unknown 

Data from http://www.nature.nps.gov/air/permits/aris/index.cfm.  – AQRV is known to be, or likely to be, sensitive to air pollution. 

No – indicates that the source is not sensitive to air pollution. Unknown – indicates insufficient park-specific information to determine if resource is sensitive for the park. 

* Fish consumption advisories have been issued by the state for the park due to unsafe levels of one or more toxics. 

1The NPS has identified visibility as a sensitive AQRV in every unit of the National Park System. 2Ozone-sensitive plant species have been identified in the park (http://www.nature.nps.gov/air/Permits/ARIS/docs/Ozone_Sensitive_ByPark_3600.pdf). 3Surface waters in the park are susceptible to acidification or eutrophication from atmospheric deposition of hydrogen ions, nitrogen, and/or sulfur. 4Soils in the park are susceptible to acidification or eutrophication from atmospheric deposition of hydrogen ions, nitrogen, and/or sulfur. 5Fish and/or wildlife collected in or near the park have elevated concentrations of mercury and/or other toxic pollutants (e.g., chlordane, PCBs). 6Dark night skies, which can be degraded by air pollution, possess value as scenic, natural, and scientific resources. 
26 

1.6.2 Water resources monitoring 

A review of water resources in individual network parks, baseline water-quality inventory data and 

analysis, clean water action plans, water quality standards for Texas and New Mexico, and water 

monitoring projects in the CHDN is provided in Appendix F. Several recent reports that discussed and 

analyzed surface and groundwater status and trends in the CHDN (Reid and Reiser 2005, Huff et al. 2006, 

Porter et al. 2009) are summarized in Appendix F. Surface water quality and quantity in Amistad 

International Reservoir, an impoundment of the Rio Grande near Del Rio, Texas, are monitored 

extensively by the International Boundary and Water Commission (IBWC) (http://www.ibwc.state.gov) 

and the Texas Commission on Environmental Quality (TCEQ) (http://tceq.state.tx.us) because of its 

importance as a regional source of water for the United States and Mexico. The surface water quality and 

flow rates of the Rio Grande are also monitored by IBWC and TCEQ. The CHDN will periodically 

review TCEQ 303(d) listings to determine the current regulatory status of Amistad International 

Reservoir and upstream segments of the Rio Grande; however, the reservoir itself will not be directly 

sampled by the CHDN network, nor addressed in the conceptual models presented in Chapter 2. 

Under Section 305(b) of the Clean Water Act, each state is required to conduct water quality surveys to 

determine the overall health of the waters of the state, including whether or not designated uses are being 

met, and report to the Environmental Protection Agency (EPA) every two years. When impaired water 

bodies are identified, they are included in 303(d) priority lists in order to limit discharges of specific 

contaminants to that water body. A portion of Rio Grande Segment 2307, upstream from BIBE, is listed 

as an impaired water body under Section 303(d) of the Clean Water Act because of excessive fecalindicator bacteria levels. Rio Grande Segment 2306, located just above Lake Amistad, will be listed in 

2010 for impaired excessive sulfate concentrations and total dissolved solids. Although no other CHDN 

surface waters were are on the 303(d) list as of March 2010, the Rio Grande adjacent to BIBE and 

throughout the wild and scenic river (RIGR) segment has been designated by TCEQ as Special Concern 

because of excessive algae (chlorophyll a) and nutrient concentrations (total phosphorus) in Segment 

2306 above Amistad Reservoir, and nitrate concentrations in the reservoir (TCEQ Segment 2305). 

A 196-mile segment of the Rio Grande, from Mariscal Canyon to the Terrell–Val Verde county line, was 

designated as a wild and scenic river by the U.S. Congress in 1978. U.S. rivers with this designation are 

to be preserved in their free-flowing condition, and their associated ecosystems are to be actively 

protected in their natural state. Some states have developed lists of Outstanding National Resource Waters 

(ONRW) under EPA guidance. There are no official ONRWs in the CHDN; however, several streams and 

other surface-water bodies (including springs) appear to be of outstanding quality and are critically 

important to their respective parks: Devils River (AMIS), Langford Hot Springs Complex (BIBE), River 

Mile 832-808 (BIBE and RIGR), Rattlesnake Springs (CAVE), McKittrick Creek (GUMO), and Lake 

Lucero playa (WHSA). These surface waters are located in areas of little or no human habitation, 

industrial development, or agricultural practices where the drainage basins are relatively undisturbed by 

human activities. 
27 

Chapter 2: Conceptual Models 

2.1 Conceptual Models 

Conceptual models of ecological systems are “caricatures of nature” (Holling et al. 2002) designed to 

describe and communicate ideas about how nature works. Conceptual models provide a way to organize 

current understanding of ecosystem structure and processes and explore hypothesized linkages among 

system components. Conceptual models also improve communication among scientists from different 

disciplines, between scientists and managers, and between 

managers and the public. 

Conceptual models are essential to the design of credible 

and effective ecological monitoring programs. Ecological 

systems are highly integrative and complex, and their 

response to novel environmental or biotic conditions is 

often poorly understood. When used to inform long-term 

monitoring, the intent of conceptual models is not to 

represent the full complexity of a system, but rather to use 

current knowledge to identify a limited set of integrative 

elements that provide information on multiple aspects of 

ecosystem condition (Noon 2003). Moreover, conceptual 

models motivate hypotheses regarding consequences of 

natural and anthropogenic processes on system structure 

and function. Conceptualizing the external processes that 

influence ecosystems (i.e., drivers), the key products of 

human activities or natural events that alter ecosystem 

integrity (i.e., stressors), and likely pathways of degradation 

and attendant changes in system structure and function aids in identifying key system indicators or vital 

signs. Concentrating monitoring efforts on these vital signs ensures the collection of information useful 

for understanding ecological condition and change, and for informing park management decisions. 

2.2 Conceptual Model Approach 

The CHDN adopted a modified version of the interactive-control model (Chapin et al. 1996, Jenny 1941) 

as the overarching framework for conceptual model development (Figure 2.2-1). This model, also known 

as the Jenny-Chapin model, defines state factors and interactive controls central to the structure and 

function of sustainable ecosystems. Jenny (1980, 1941) proposed that soil and ecosystem processes are 

determined by five state factors: global climate, potential biota, relief (topography), parent material, and 

time since disturbance (Figure 2.2-2A). Chapin and others (1996) extended this framework to define a set 

of four interactive controls regulated by the five state factors. These interactive controls (regional climate, 

soil resources, major functional groups of organisms, and disturbance regime) govern and respond to 

ecosystem attributes (Figure 2.2-2B). Including hydrologic resources as an interactive control, the JennyChapin model can be applied to aquatic as well as terrestrial ecosystems (Chapin et al. 1996). Regional 

climate and disturbance regimes are external to the system and are categorized as drivers of ecosystem 

structure and function. Soil and hydrologic resources, and functional groups, encompass system states and 

processes that influence overall system structure and function. Functional groups pertain to species or 

species assemblages likely to have profound effects on ecosystem characteristics following their 

introduction or loss from a system (Chapin et al. 1997, Vitousek 1990). 

Key Terms 

Degradation – reduction in the capacity 

of an ecosystem to perform natural 

functions (e.g., maintenance of native 

biota). 

Disturbance – discrete event that 

changes ecosystem conditions. Natural 

disturbances are within the range of 

natural variability. 

Driver – external forces exerting control 

on an ecosystem (e.g., weather). 

Stressors – human activities, or natural 

events outside the range of natural 

variability, that alter ecological integrity. 
28 

Topography

Hydrologic processes,

transport of pollutants,

human uses

Parent material

Climate, age, hydrologic

processes

Biota

Genetic integrity, population 

stability, habitat availability, 

invasive species, rare/T&E spec

Time

Since disturbanc

systemic and spe

specialization, cy

Global & Regional Climate

Increasing CO2 and temperature,

changing precipitation patterns,

airborne pollutants

Regional Climate

Precipitation, temperature, 

seasonality, phenology

Soil resources

Nutrient cycling,

Microbial function;

drives aboveground

productivity

Functional groups

Flora, fauna,

species’ diversity

Disturbance regime

Fire, flood, climatic events

(e.g., drought), human land uses

Ecosystem processes

3

Primary & secondary productivity,

nutrient & water cycling

Hydrologic resources

Flow cycles, nutrient cycling:

driver of productivity

Figure 2.2-1. Illustration of the Jenny-Chapin model, showing relationships among state factors, interactive controls, and ecosystem procFigure 2.1.1 in Britten et al. 2007). 
29 

Natural Disturbance Climate, Atmospheric

Conditions

Shrub, grass, BSC Shrub, grass

Soil compaction

Infiltration Runoff

A

B

C

Soil Resources

Vertebrates

Invertebrates

Stressors

Vegetation

Trampling

Eroded 

State

transition

Shrub Shrub, BSC

Shrubsteppe state Eroded

Shrubsteppe state

Shrub, grass

Figure 2.2-2. Illustration of the hierarchical conceptual model scheme used to identify vital signs for monitoring (O’Dell 

et al. 2005). A – ecosystem characterization model showing drivers (ovals), functional components (rectangles), and 

stressors (dashed rectangles), B – ecosystem dynamics model using a state and transition framework, C – 

mechanistic model illustrating the degradational pathway of a stressor (e.g., trampling). 
30 

A key aspect of the Jenny-Chapin model is the associated hypothesis that interactive controls must be 

conserved for an ecosystem to be sustained. Large changes in any of the four interactive controls are 

predicted to result in an ecosystem with different characteristics than the original system (Chapin et al. 

1996). For example, major changes in soil resources can greatly affect productivity, recruitment, and 

competitive relations of plants, and result in substantive changes in the structure and function of plant 

communities and higher trophic levels. 

Using the Jenny-Chapin model as a central theme (Figure 2.2-1), a nested hierarchy of conceptual models 

(Figure 2.2-2) was used to identify specific drivers and stressors, plausible stressor-induced degradation 

pathways and ecosystem responses, and measures and vital signs indicative of the domain of natural 

conditions and transition to degraded conditions. 

The nested hierarchy consists of three general types of conceptual models: 

 Ecosystem Characterization Models (Figure 2.2-2A) are generalized models that include a list of 

state variables and forcing functions important to the ecosystem and the focal problem, and also 

illustrate processes connecting components (Jorgensen 1986). These models provide a framework for 

organizing information from discussion and literature review around the five interactive controls. 

 Ecosystem Dynamics Models (Figure 2.2-2B) present hypotheses about ecosystem dynamics; that is, 

how and why ecosystems change as a consequence of interacting natural and human factors. Stateand-transition models are used to depict system dynamics and pose hypotheses about ecological 

thresholds, transitions among states, and the effect of management activities on state transitions 

(Bestelmeyer et al. 2003, Jackson et al. 2002, Stringham et al. 2001). Models are developed for broad 

functional groupings of ecosystems, with eventual development of site-specific models of selected 

systems. 

 Mechanistic Model (Figure 2.2-2C) provide details about the actual ecological processes responsible 

for patterns depicted in the dynamic models. These models provide insight into pathways and primary 

and secondary effects of particular stressors, highlight potential monitoring attributes or measures, 

and illustrate the linkage of these attributes in the context of the broader ecosystem. Models are 

developed for single or multiple combinations of stressors. 

2.3 Summary of Conceptual Models for Six Chihuahuan Desert 

Network Ecosystems 

Ecosystem characterization models and narratives for each CHDN system are provided below to illustrate 

interactive controls (drivers, soil/water resources, functional groups). Stressors and key degradational 

processes are also included in these models, and potential ecosystem measures to characterize degraded 

system conditions are listed at the end of each section. Published hierarchical conceptual models for 

related systems guided the identification of interactive controls, stressors, and degradation pathways for 

the Desert Ecosystem (Miller 2005), Montane Ecosystem (Thomas et al. 2006: Appendix I), and the 

riparian component of River Ecosystems (O’Dell et al. 2005: Appendix J). For other CHDN ecosystems, 

only ecosystem characterization models were developed. For all ecosystems, details of system dynamics 

were acquired from literature review and expert opinion. Chapter 3 describes how conceptual models 

were used in the selection of CHDN vital signs. 

2.3.1 Desert Ecosystem 

The Desert Ecosystem occurs below 1,370 m (4,500 ft) in elevation, and includes basins, low-lying 

alluvial or colluvial fans, bajadas, and mesas. About 77% of the CHDN is classified as desert, and this 

ecosystem occurs in five of the seven CHDN parks. The Desert Ecosystem is characterized by low 
31 

precipitation, nutrient availability, and net primary productivity, but high plant diversity (Whitford 2002). 

Vegetation consists of sparse cover of shrub and desert grasslands, and biological soil crust. Salt flats and 

dunes also are discrete features within this system. Although limited in extent, springs, seeps, perennial 

and ephemeral streams, and playas (also ephemeral) occur within the desert system. These aquatic 

systems were not treated separately because they are embedded in the surrounding desert soils and 

vegetation with connections among all systems. The ecosystem characterization model for the Desert 

Ecosystem is shown in Figure 2.3.1, and discussed below. 

Regional climatic and atmospheric conditions are key drivers of the desert system. Precipitation regulates 

water-limited ecological processes, such as primary production, nutrient cycling, and plant reproduction 

(Noy-Meir 1973, Comstock and Ehleringer 1992, Whitford 2002). Interactions among seasonality, spatial 

variability, and duration of precipitation events create pulses of water input (Appendix F; Snyder and 

Tartowski 2006) and determine ecosystem response to precipitation. Seasonality influences the 

partitioning of precipitation among evaporation, transpiration, runoff, drainage, and soil-water storage, 

and is a determinant of vegetative lifeform dominance (Comstock and Ehleringer 1992). Small 

precipitation events drive soil-surface processes, such as nutrient mineralization and volatilization, with 

larger events initiating seed germination and soil-water recharge (Ehleringer et al. 2000). Precipitation 

intensity, in combination with soil characteristics and soil-surface features, determine infiltration and 

runoff levels (Whitford 2002, Breshears et al. 2003). Orographic effects, rain-shadows, and seasonal 

storm features determine spatial pattern of precipitation, which can be highly variable in summer months. 

In addition, chemical composition of rainfall, and atmospheric nitrogen and carbon, affect metabolic 

processes of soil microbes and plants (Schlesinger et al. 2006). Large, rapid pulses of rainfall can cause 

flooding and create temporary resources, such as playa lakes. The temperature regime, driven by solar 

insolation, results in evaporative loss and water-stress in plants during summer months, and imposes 

limitations to productivity. Desert plant and animal species have adapted special features to persist under 

conditions of low water availability and high solar radiation influx (Whitford 2002). Over the long term, 

climate-driven processes interact with geologic materials and landforms to form or change desert soils 

(Monger and Bestelmeyer 2006). 

Eolian (wind) processes also play a prominent role in the Desert Ecosystem. Winds modify the energy 

and water balances of plants and soils (Gillette and Pitchford 2004, Okin et al. 2006), and redistribute 

soils and nutrients. 

Ecological processes of the desert system are mediated by geology and hydrology. Landforms resulting 

from geologic processes create a template influencing the structure and composition of desert resources 

(Wondzell et al. 1996, Monger and Bestelmeyer 2006). Bajadas and alluvial fans are common landforms 

throughout the Desert Ecosystem, and the parent materials that create these landforms mediate soil 

properties and, subsequently, associated vegetative communities (Whitford 2002). The topography of 

desert systems is relatively flat, but minor variations are sufficient to create different microclimates for 

plants and animals (Whitford 2002). Slope and channel characteristics influence rates of water flow 

during precipitation (Simmers 2003). 
32 

GEOMORPHIC &

HYDROLOGIC CONDITIONS

landform, parent material, flow

channel, slope, aspect

determines base materials, flow 

direction, modifies radiation

NATURAL

DISTURBANCE

climatic extremes, floods, wildfire

initiates veg. succession, 

sediment and water pulses

REGIONAL CLIMATIC &

ATMOSPHERIC CONDITIONS

precipitation, wind, radiant energy, 

CO2, N2

provides thermal and chemical inputs, 

regulates ecosystem processes

1 2 4 SOIL RESOURCES

organic matter, minerals, 

water

nutrient & hydrologic cycling, 

faunal habitat

VEGETATION

Biocrust, plant patches to 

landscape cover

primary production, 

faunal habitat

FAUNA

functional groups, focal species

secondary production, 

predation, ecoengineering

CLIMATIC

CHANGE

increased temp.,

altered precip.

AIR POLLUTION

increased ozone,

N2, SO4

ADJACENT LAND 

USE

water withdrawal 

increased material 

flow, faunal 

disruption

INVASIVE 

EXOTIC SPECIES

loss of natives, floral 

/ faunal disruption

HISTORIC LAND 

USE-GRAZING

increased erosion, 

changes in land 

cover and fauna

A B C A B 1 2 3 B 1 2 3

3 SPRINGS / STREAMS

water, sediment

hydrologic cycling, matter 

flow, biotic production, 

faunal habitat

4 4

RECREATION 

AND LOCAL USE

compaction, 

pollution, faunal 

disruption

C

Woody-plant

encroachment,

Exotic species invasion,

Soil erosion

Exotic species 

invasion, Soil 

erosion, Acidification

of aquatic resources

Soil erosion, Exotic 

species invasion,

Pollution-mediated

changes in aquatics

Exotic species 

invasion

Woody-plant 

encroachment,

Exotic species 

invasion, Soil erosi

Exotic species invasion,

Soil erosion, Terrestrilization

of aquatic systems, Large-scale 

habitat loss & fragmentation

altered

hydrology

B altered

regimes

altered climatic,

atmospheric conditions

A

1 2 3 A B 1 2 3 4 B C 1 2 3 4

Figure 2.3.1. Ecosystem characterization model for the CHDN Desert Ecosystem. Solid ovals are drivers and interactive controls. Solid rcomponents that are interactive controls. Dashed rectangles are stressors, and dotted rectangles with blue text are key degradation proc

each stressor (described in Table 2.3.1). Text for interactive controls indicates components or structure followed by function. Text for streeffects.
33 

Natural disturbances include extreme climatic events, flooding, and wildfire. Extended dry periods, 

particularly when coupled with hot, dry winds, can cause mass mortality of perennial grasses. With the 

loss of perennial cover, sites are more vulnerable to soil erosion by wind and water. In certain regions of 

the CHDN, current vegetation composition can be attributed to drought-induced die-off events more than 

50 years ago (Peters et al. 2006). Periodic flash-flood events can occur during summer monsoonal rains, 

and are a primary source of long-range material transport and groundwater recharge within the Desert 

Ecosystem (Whitford 2002, Snyder et al. 2006). Through biotic interaction with species, such as 

spadefoot toads (Scaphiopus spp.), recharged playa beds can become oases of available nutrients and 

local redistribution (Whitford 2002). Lightning ignites natural fires that can cause extensive heterogeneity 

in landscapes, facilitate mineralization, and transport nutrients into the atmosphere. Historically, fire is 

thought to have played a vital role in maintaining desert grasslands and inhibiting the incursion of shrubdominated associations (McPherson 1995). The role of fire in shrub dominated communities of the Desert 

Ecosystem is variable and likely less influential than soil integrity and seed dispersal (Dick-Peddie 1993, 

Drewa and Havstad 2001, Valone 2003). 

Soil resources mediate the productivity and function of desert systems. The availability of soil moisture 

and nutrients is a primary factor limiting productivity in the Chihuahuan Desert (Whitford 2002, Snyder 

et al. 2006). Soil stability, texture, and structure influence mineralization, soil water-holding capacity, soil 

biota composition, and rooting depth, all of which influence plant composition, distribution, and growth 

(MacMahon and Wagner 1985, Whitford 1996, Huenneke and Schlesinger 2006). The resilience of a site 

is largely related to soil properties (Karlen et al. 1997, McAuliffe 2003). Very shallow or compacted soil 

layers that are lime-rich can provide favorable substrates for cacti while creating less favorable 

environments for other plant species (Dick-Peddie 1993). At White Sands NM, soil created from waterleached dolomite forms gypsum crystals in a large playa lake bed (Kiver and Harris 1999) and eventually 

forms gypsum dunes (Langford 2003). Plants adapted to these soils are limited and have a high tolerance 

of gypsum (Dick-Peddie 1993). Loss and redistribution of soil resources can ultimately lead to 

desertification (Schlesinger et al. 1990, Gillette and Pitchford 2004). 

Vegetation provides energy for higher trophic levels, and the above-ground structure of vascular plants 

protects soils from erosive rain drops, wind, and overland water flow, and enhances the retention of soil 

resources (Gillette and Prichard 2004, Abrahams et al. 2006). Plants also modify the physical 

environment through shading and litter deposition. Vegetation is a key component of fauna habitat 

(Naranjo and Raitt 1993, Jorgensen et al. 2000, Gutzwiller and Barrow 2002, Menke 2003). Shrub and 

grass growth forms are the main primary producers in the Desert Ecosystem (Huenneke and Schlesinger 

2006). Succulents, such as cacti and agaves, are another defining plant growth form of this ecosystem. 

Although trees are often absent, CHDN plant communities are among the most diverse of any desert 

system. 

Biological soil crust (BSC)—microbial communities consisting of fungi, algae, cyanobacteria, lichens, 

and moss (Belnap and Lange 2001)—contribute to site potential and productivity. Well-developed crusts 

directly influence soil stability and facilitate growth of desert mosses. Mosses provide organic matter and 

enhance moisture retention, which facilitates germination, growth, and survival of vascular plant species. 

Nitrogen fixation by cyanobacteria is an important ecosystem function of BSC, which is highly 

susceptible to air pollution and trampling. Recolonization of disturbed sites may require from decades to 

centuries. 

Springs, seeps, and ephemeral and perennial streams are rare but functionally important elements of the 

Desert Ecosystem. These systems provide specialized habitats and life-sustaining resources for plants and 

animals and can greatly augment local biodiversity. Because they are isolated, desert springs are often 

sites of speciation or endemism (Hubbs et al. 2002, Collyer et al. 2005, Wallace et al. 2005). The most 

common form of this resource occurs as ephemeral arroyos and draws, which cross the desert basins of 
34 

CHDN park units (Appendix F). These aquatic systems are functionally related to groundwater levels 

(e.g., see Stevens and Springer 2004). In addition, riparian vegetation is limited to drainage systems with 

more persistent or predictable water sources at or nearer the surface than in surrounding lands. Water flow 

and riparian environments are also common avenues for the spread of invasive plant species, such as salt 

cedar (Tamarix spp.). 

A wide variety of invertebrates and vertebrates is found in this ecosystem (e.g., see Appendix C, Whitford 

and Bestelmeyer 2006). Both faunal groups function to transfer minor amounts of energy (usually <10% 

of net primary production; Whitford and Bestelmeyer 2006) and, more importantly, to regulate system 

processes via ecological feedbacks (Chew 1974). Key functional groups of fauna, their particular 

environmental associations, and their roles in regulating ecosystem processes have recently been 

summarized by Whitford and Bestelmeyer (2006: Table 12-2). Kangaroo rats (Dipodomys spp.) and 

subterranean termites are notable keystone groups (Nash and Whitford 1995, Kerley et al. 1997, Fields et 

al. 1999, Krogh et al. 2002, Whitford and Bestelmeyer 2006). Burrowing activity, harvesting of flowers, 

and seed caching by species of kangaroo rats influence establishment of native herbaceous plants (Fields 

et al. 1999), changes in local vegetation composition (Kerley et al. 1997, Brown and Heske 1990), and 

redistribution of nutrients (Whitford 2002). Kangaroo rats also are an important food resource for a 

diverse assemblage of predators. Subterranean termites can process 3–50% of leaf litter (Whitford and 

Bestelmeyer 2006: Table 12-1), returning several nutrients, including nitrogen, phosphorous, and sulfur, 

to the available nutrient pool (Whitford and Bestelmeyer 2006). Soil porosity and water infiltration are 

increased by gallery development and expansion. Nutrient cycling and water infiltration ultimately affects 

composition and productivity of vegetation communities. Fauna contribute to biological diversity, and 

some species are of special conservation concern (Appendix C). 

Increasing levels of atmospheric CO2, increasing soil and air temperatures, and altered precipitation 

patterns are likely to affect physiological processes and competitive relations of vascular plants, nutrient 

cycles, hydrologic processes, and natural disturbance regimes. All of these can greatly alter the structure 

and functioning of dryland ecosystems (e.g., Alward et al. 1999, Ehleringer et al. 2000, Smith et al. 2000, 

Weltzin et al. 2003) and the sensitivity of these systems to other anthropogenic stressors. Increases in CO2

from local and global sources enhance growth rates of C3 shrubs over native grasses, and of C3 exotic 

annual grasses. Increase in shrub cover decreases herbaceous cover due to light competition, with a 

concomitant increase in bare ground between shrub canopies. Higher exposure of bare ground increases 

the risk of wind and water erosion of soil, and subsequent loss of site potential and biotic integrity. 

Expansion of woody shrubs impacts animal species associated with herbaceous plant communities. 

Warming and lower precipitation trends predicted for dryland systems are likely to increase evapotranspiration and offset temperature-driven increases in plant production (Saleska et al. 1999). 

Sources of air pollutants, such as particulates, tropospheric ozone, and nitrogen deposition, include coalburning power plants, oil and gas developments (which increase airborne nitrates and sulfates), and 

industrial point and non-point sources from Mexico. Nitrogen deposition increases the susceptibility of a 

site to exotic plant invasion (Asner et al. 1997, Galloway et al. 2003, Fenn et al. 2003). Nitrogen 

deposition in the form of acid rain has the potential to impact water quality and degrade cultural features, 

such as pictographs. Ozone formed from nitrogen emissions poses a risk to human health, and particulates 

impact visitor experience by impairing scenic vistas. 

Adjacent land use consists of agricultural and urban development, groundwater pumping, energy and 

mineral development, and ranching of exotic species. These activities affect park lands directly through 

the deposition of atmospheric pollutants, by increasing invasion by exotic plants and animals, and by 

altering hydrological regimes of waters that originate outside the park. Altered hydrologic regimes can 

decrease plant cover and increase frequency and extent of soil erosion. Land-use practices increase the 

risk of mortality to park wildlife that range onto adjacent lands, and potentially impact migration and 
35 

dispersal abilities of species. Loss of regional connectivity of species habitat leads to insularization of 

park lands. 

Recreation activities affect park conditions in many ways. Waste management and backcountry humanwaste disposal can impact water quality. The release of unwanted pets and introduction of non-native 

plants are also potential threats. Social trailing, especially in fragile or sensitive habitats, leads to 

compaction of vegetation, BSC, and soils, with subsequent impacts to water quality, soil stability, soilwater infiltration rates, and overall site potential. 

Invasive/non-native species can replace native species, leading to loss of biodiversity, and affect 

ecosystem change and degradation. The list of non-native animal and plant species affecting CHDN park 

units is extensive (Appendices C and D). NPS mowing and maintenance practices, visitor use, and 

adjacent land practices increase the risk of exotic species invasion. These invasions can displace native 

species through disease, competition, and predation, thereby changing vegetation and animal 

communities. Exotic plants impact water quantity and affect fire regimes by increasing fuel loadings and, 

ultimately, fire frequency. Subterranean cave systems are especially sensitive to the introduction of exotic 

plants. 

Historical grazing is considered a stressor given its impact on desert systems. The majority of CHDN 

desert grasslands were severely overgrazed prior to the transfer of these areas to the National Park Service 

(Wondzell and Ludwig 1995). Conversion of grasslands to shrublands is attributed to the removal of 

palatable native grasses, and to trampling of soils and vegetation. The reduction of grasses promoted an 

increase in shrub density, and soil disturbance led to the establishment of exotic invasive plants. Loss of 

herbaceous cover due to shading by shrubs increases amount of bare ground and soil erosion potential. 

Historical grazing alone, however, may not be responsible for this conversion, given the coincidence of 

global climate patterns (e.g., end of the Little Ice Age, ca. 1900) and the rapid increase in domestic 

livestock across the Southwest and Trans-Pecos regions (Neilson 1986). Also, causes of the shift of 

grasslands to shrublands are complex (Peters and Gibbens 2006), and involve multiple historical and 

ecological factors (Cole and Monger 1994, Fredrickson et al. 2006, Housman et al. 2006, Peters et al. 

2006, Peters and Havstad 2006). Monitoring to determine continued shrubland conversion and areas with 

trespass grazing is important to inform management of this important resource change. 

Seven key degradation processes are predicted (Figure 2.3.1, Table 2.3.1). These processes can lead to 

conditions beyond the naturally variability of desert systems, and have important implications to 

ecosystem sustainability. Potential measures that would provide early warning of system degradation are 

listed for each process. 
36 

Table 2.3.1. Key degradation processes in the Desert Ecosystem, stressors and ecological effects 

associated with these processes, and potential measures that would characterize degradation 

processes and effects. 

Degradation process Stressors Ecological effects Potential measures 

Woody-plant 

encroachment 

The reduction of 

perennial grasses from 

grazing, CO2

enrichment under 

climatic change 

Altered soil-hydrologic and 

nutrient cycling and habitat 

structure, loss of 

herbaceous communities 

and associated animal 

species, increased soil 

exposure and erosion 

Vegetative composition and 

structure, occurrence of trespass 

grazing, climatic-atmospheric 

elements, abundance of 

grassland-associated animal 

species 

Exotic species invasion Recreation and local 

use, adjacent land-use 

activities, climatic and 

atmospheric changes 

Plants: Altered nutrient 

dynamics, soil-water 

dynamics, major shift in 

functional-group structure 

Animals: Loss of native 

fauna 

Vegetative composition and 

structure, adjacent land-use 

activities, climatic and 

atmospheric elements, 

abundance of exotic animal 

species 

Soil erosion and 

redistribution 

Trampling by visitors 

and trespass grazing, 

air pollution, climatic 

change, dewatering of 

surface and 

groundwater by 

adjacent land-use 

activities 

Erosion and loss of soil 

function due to reduction of 

biological soil crusts, soil 

compaction, soil-surface 

roughness, soil-aggregate 

stability, and water 

infiltration; decreased N 

fixation; changes in 

vegetative composition and 

structure 

Depth, structure, and stability of 

soils; biological soil crust cover 

and distribution; vegetative 

composition, structure, and 

pattern; climatic and atmospheric 

elements, adjacent land-use 

activities; trespass grazing 

frequency and severity 

Acidification of aquatic 

resources 

Acid rain (atmospheric 

nitrogen) 

Loss of native aquatic biota Water chemistry, aquatic biota 

structure and composition, 

atmospheric elements 

Large-scale habitat loss 

& fragmentation 

Adjacent land-use 

activities 

Regional-scale habitat loss, 

reduced connectivity of 

metapopulations, reduced 

ingress and egress potential 

Land-cover, land-use, landcondition patterns on park and 

adjacent lands 

Terrestrialization - 

conversion of aquatic 

systems to terrestrial 

vegetation 

Adjacent land use 

(streamflow depletion) 

Loss of springs, ephemeral, 

perennial stream function 

with conversion of aquatic 

vegetation to upland or 

xeroriparian species 

Surface and groundwater flow 

rates, adjacent land-use 

activities, land-cover and landuse patterns on park and 

adjacent lands, stream/spring 

vegetation structure and 

composition, climatic elements 

Pollution-mediated 

changes in aquatic 

systems 

Recreation and local 

use 

Altered biotic structure, 

composition, and function of 

aquatic systems 

Patterns of recreation use, water 

chemistry, aquatic biotic 

structure and composition 
37 

2.3.2 Foothill Ecosystem 

The Foothill Ecosystem occurs at elevations between 1,370 m and 1,981 m (4,500–6,500 ft), and includes 

piedmonts, foothills, mesas, and canyons. This ecosystem comprises about 9% of the CHDN, and 

foothills occur in four CHDN parks. The Foothill Ecosystem is a transition area between the lower desert 

and higher montane environment. As with the Desert Ecosystem, springs, seeps, and perennial or 

ephemeral streams are included as subsystem elements. Habitat types of this ecosystem include 

grasslands, shrublands, and woodlands (see Appendix D for more detailed description). The ecosystem 

characterization model for the Foothill Ecosystem is shown in Figure 2.3.2, and discussed below. 

Focal resources of the Foothill Ecosystem are shaped by the same three categories of drivers described for 

the Desert Ecosystem: climate and atmospheric conditions, geomorphic and hydrologic conditions, and 

natural disturbance. The nature and magnitude of influence of these drivers differ from the Desert 

Ecosystem as a function of topography and climate variation associated with higher elevation. Upper 

elevations receive more precipitation and have cooler temperatures. Surface water channels can be more 

incised, narrower, and have steeper gradient than arroyos and washes of the desert basins; thus, there is 

greater erosion potential during periods of high precipitation. Low-intensity ground fires were a natural 

disturbance of the shrub and woodland components of the foothill system, and historically maintained a 

mosaic of age classes and patch patterns across the landscape. 

As in the Desert Ecosystem, vegetation provides the primary source of production, stabilizes soils, and 

provides food and cover for other organisms. Given the greater topographic relief than in the Desert 

Ecosystem, orographic effects provide additional stratification of local environments that can enhance 

beta-diversity. Also, higher levels of soil organic matter enhance water and nutrient retention, allowing 

for higher primary production. Cacti, yucca, and agave plant forms are present, and shrub forms may also 

dominate some plant communities. Large expanses of grassland are atypical, except on high mesas. Trees 

are common. 

Streams within open to steep-walled canyons may support development of narrow but distinct riparian 

corridors. The cooler, moister conditions of foothill canyons and draws provide plant-rich microcosms 

and, in some cases, form stringers of closed-canopy woodlands with developed understories of herbs and 

shrubs (Baker et al. 2004). These areas provide refugia for organisms during dry years. Springs and seeps 

also provide localized spots of diversity and may be associated with canyons and riparian systems. 

Riparian corridors of the Foothill Ecosystem serve as primary routes of biotic transition between the 

upper elevations and desert basin. 

The Foothill Ecosystem includes species that are less adapted for life in arid conditions. Bird 

communities can be particularly diverse in riparian or canyon habitats of the Foothill Ecosystem. The 

structure, composition, and microclimate of riparian vegetation provide suitable nesting and foraging 

conditions for a number of bird species (Mills et al. 1991, Bryan and Karges 2001), including some 

threatened or endangered species, such as Mexican spotted owls (Strix occidentalis lucida; Ward et al. 

1995). Strong keystone roles by species in the Foothill Ecosystem have not been identified. However, 

species such as pinyon and scrub jays (Gymnorhinus cyanocephalus and Aphelocoma coerulescens, 

respectively) and collared peccaries (Tayassu tajacu) may aid in the dispersal of mast-bearing plant 

species and cacti. Caching of pinyon nuts or juniper berries by jays also likely provides food sources for 

several rodents (Christensen and Whitham 1993, Stotz and Balda 1995, Vander Wall 1997). 
38 

Figure 2.3.2. Ecosystem characterization model for the CHDN Foothill Ecosystem. Solid ovals are drivers and interactive controls. Solid components that are interactive controls. Dashed rectangles are stressors, and dotted rectangles with blue text are key degradation proc

each stressor (described in Table 2.3.2). Text for interactive controls indicates components or structure followed by function. Text for streeffects.

GEOMORPHIC &

HYDROLOGIC CONDITIONS

landform, parent material, flow

channel, slope, aspect

determines base materials, flow

direction, modifies radiation

NATURAL

DISTURBANCE

climatic extremes, floods, wildfire

initiates veg. succession, 

sediment and water pulses

REGIONAL CLIMATIC &

ATMOSPHERIC CONDITIONS

precipitation, wind, radiant energy, 

CO2, N2

provides thermal and chemical inputs, 

regulates ecosystem processes

1 2 4 SOIL RESOURCES

organic matter, minerals, 

water

nutrient & hydrologic cycling, 

faunal habitat

VEGETATION

Biocrust , plant patches to 

landscape cover

primary production, 

faunal habitat

FAUNA

functional groups, focal species

secondary production, 

predation, ecoengineering

CLIMATIC

CHANGE

increased temp.,

altered precip .

AIR POLLUTION

increased ozone,

N2, SO 4

ADJACENT LAND 

USE

water withdrawal

increased material 

flow, faunal

disruption

INVASIVE 

EXOTIC SPECIES

loss of natives, floral 

/ faunal disruption

HISTORIC LAND USE -

GRAZING, FIRE 

SUPPRESSION

increased erosion, 

changes in land cover

and fauna

A B C A B 1 2 3 B 1 2 3

3 SPRINGS / STREAMS

water, sediment

hydrologic cycling, matter 

flow, biotic production, 

faunal habitat

4 4

RECREATION 

AND LOCAL USE

compaction, 

pollution, faunal

disruption

C

Woody-plant encroachment, 

Exotic species invasion, 

Soil erosion, 

High rates of tree mortality

Exotic species 

invasion, Soil erosion, 

High rates of tree 

mortality, Acidification 

of aquatic resources

Exotic species 

invasion

Woody-plant encroachment,

Exotic species invasion,

Soil erosion, High tree

densities

altered

hydrology

B altered

regimes

C

altered climatic,

atmospheric conditions

A

1 2 3 A B 1 2 3 4 B C 1 2 3 4

Exotic species invasion,

Terrestrilization of aquatic

systems, Large -scale 

habitat loss & fragmentation

Soil erosion, Exotic 

species invasion,

Pollution-mediated 

changes in aquatics
39 

Air pollutants and climatic change are modeled to have two general effects. Similar to the Desert 

Ecosystem, CO2 and nitrogen enrichment can enhance woody-plant encroachment and establishment of 

exotic plants. Additionally, air pollutants, such as ozone, can reduce tree growth due to increased foliar 

injury, and temperature-induced stress can increase susceptibility of trees to insects and pathogens, both 

of which are modeled to increase tree mortality. Increased downed-woody fuels on the landscape 

increases the risk of high-severity fires. 

Human uses are modeled in two general ways. Adjacent land use impacts quantity and quality of surface 

and ground waters through domestic extraction or as a byproduct of oil and gas development. Dust 

emissions from road and oil/gas pad construction, as well as atmospheric pollutants from vehicle, drill, 

and pump engines, can lead to resource enrichment and favor the spread of exotic invasive plants. Landuse activities near park boundaries can promote the spread of invasive plants and animals into parks and 

alter egress and ingress potential for wildlife species. Visitor use impacts parks through trampling of soil 

and vegetation, by introducing exotic invasive species, and through repeated use of aquatic systems. 

Disruption of soil stability through trampling has ramifications for soil-water runoff, soil erosion, and 

decreased site potential. Repeated trampling around springs, seeps, and streams reduces the vegetation 

structure that provides shading and nutrient inputs to aquatic resources. Human pollution in commonly 

used riparian areas impacts water quality and associated biotic communities. 

Exotic invasive species can have a large impact on foothill systems. Feral hogs (Sus scrofa) can 

drastically affect the structure of riparian vegetation and springs, and limit resources for collared 

peccaries. Trespass cattle also occur throughout the foothills and continue to alter plant composition with 

the removal of palatable native grasses and by trampling. 

Historical grazing and fire suppression are modeled as interacting stressors. Grazing occurred throughout 

the CHDN foothills prior to park designations, and contributed to the conversion of native grasslands to 

shrublands and to the spread of exotic plants. Fire suppression over the last century has significantly 

altered the fire regime. The increase in woody biomass due to excessive livestock grazing in the past and 

the continuation of fire suppression has increased fuel loads and the risk of high-severity fires. After highseverity fires, the loss of soil-stabilizing vegetation on steep slopes can lead to significant soil erosion and 

long-term or permanent loss of site potential. Stand-replacing fires, especially in riparian woodlands, have 

important consequences for local biodiversity. 

Degradation processes include the seven listed for desert systems, plus high tree stocking and mortality 

(Figure 2.3.2, Table 2.3.2). The higher levels of biomass and downed-woody fuels resulting from 

historical grazing, fire suppression, and climatic and atmospheric stresses increase the risk of highseverity fire and concomitant impacts on soil properties and plant communities. 
40 

Table 2.3.2. Key degradation processes in the Foothill Ecosystem, stressors and ecological 

effects associated with these processes, and potential measures that would characterize 

degradation processes and effects. 

Degradation process Stressors Ecological effects Potential measures 

Woody-plant 

encroachment 

The reduction of 

perennial grasses from 

grazing, CO2

enrichment under 

climatic change 

Altered soil-hydrologic and 

nutrient cycling and habitat 

structure, loss of herb species, 

increased soil exposure and 

erosion 

Vegetative composition and 

structure, occurrence of trespass 

grazing, climatic-atmospheric 

elements 

Exotic species 

invasion 

Recreation and local 

use, adjacent land-use 

activities, climatic and 

atmospheric changes 

Plants: Altered nutrient 

dynamics, soil-water dynamics, 

major shift in functional-group 

structure 

Animals: Loss of native fauna 

Vegetative composition and 

structure, adjacent land-use 

activities, climatic-atmospheric 

elements, abundance of exotic 

animal species 

Soil erosion and 

redistribution 

Trampling by visitors 

and trespass grazing, 

air pollution, climatic 

change, dewatering of 

surface and 

groundwater by 

adjacent land-use 

activities 

Erosion and loss of soil function 

due to reduction of biological 

soil crusts, soil compaction, 

soil-surface roughness, soilaggregate stability, and water 

infiltration; decreased N 

fixation; changes in vegetative 

composition and structure 

Depth, structure, and stability of 

soils; biological soil crust cover 

and distribution; vegetative 

composition, structure, and 

pattern; climatic and 

atmospheric elements; adjacent 

land-use activities; trespass 

grazing frequency and severity 

Acidification of aquatic 

resources 

Acid rain (atmospheric 

nitrogen) 

Loss of native aquatic biota Water chemistry, aquatic biota 

structure and composition, 

atmospheric elements 

Large-scale habitat 

loss & fragmentation 

Adjacent land-use 

activities 

Regional-scale habitat loss, 

reduced connectivity of 

metapopulations, reduced 

ingress and egress potential 

Land-cover, land-use, landcondition patterns on park and 

adjacent lands 

Terrestrialization - 

conversion of aquatic 

systems to terrestrial 

vegetation 

Adjacent land use 

(streamflow depletion) 

Loss of springs, ephemeral, 

perennial stream function with 

conversion of aquatic 

vegetation to upland or 

xeroriparian species 

Surface and groundwater flow 

rates, adjacent land-use 

activities, land cover and land 

use on park and adjacent lands, 

stream/spring vegetation 

structure and composition, 

climatic elements 

Pollution-mediated 

changes in aquatic 

systems 

Recreation and local 

use 

Altered biotic structure, 

composition, and function of 

aquatic systems 

Patterns of recreation use, water 

chemistry, aquatic biotic 

structure and composition 

High tree density and 

high rates of tree 

mortality 

Historical grazing, fire 

suppression, climatic 

change, atmospheric 

pollutants 

Higher spatio-temporal 

frequency of snags and downed 

coarse-woody debris; larger 

contiguous fire patterns due to 

high fuel loads and fuel 

connectivity; erosion and loss of 

soil function due to sterilization, 

reduction in soil stability, 

reduction in site potential, and 

changes in attendant plant 

communities resulting from 

high-severity fire 

Fire regime attributes, tree 

mortality rates, tree and shrub 

structure and composition 
41 

2.3.3 Montane Ecosystem 

The Montane Ecosystem occurs at elevations above 1,981 m (6,500 ft), and includes steep-sloped terrain 

and intermittent valleys or canyons. This ecosystem comprises about 2.5% of the CHDN, and occurs in 

GUMO and BIBE. Landforms in this ecosystem are often connected to Foothill Ecosystems. Plant 

communities include pine-oak woodland, mesic mixed conifer forest and woodland, and montane 

deciduous woodland. Springs, seeps, and perennial or ephemeral streams are included as functional 

groups. The ecosystem characterization model for the Montane Ecosystem is shown in Figure. 2.3.3, and 

discussed below. 

The occurrence of woodlands and forests is directly related to the mountainous terrain and elevationmediated precipitation gradients. Ambient temperatures are generally cooler than at lower elevations, and 

vary inversely with elevation, landform, and aspect. Precipitation is greater than in lower-elevation 

systems and contributes to higher productivity relative to other CHDN terrestrial systems. The higher 

montane elevations capture and contribute substantially to the water balance of lower watersheds and 

ecosystems. The slope gradients, and high precipitation levels and rates of mineralization, facilitate 

transport of materials from the montane to the Foothill and even Desert ecosystems. 

Fire has been an important disturbance agent. In mixed-conifer forests in GUMO, fires prior to 1800 

tended to be frequent (mean fire return interval of 24 years) and small, creating mixed-age forests 

(Sakulich and Taylor 2007). A similar fire regime is documented for BIBE (Camp et al. 2006). Less 

frequent and larger fires typified the period from 1800 to 1922, when livestock grazing was introduced. 

This period corresponded to a decline in local populations of Native Americans and associated ignitions. 

Reduced fire frequency and fuel accumulation possibly increased the importance of lightning ignitions 

(Sakulich and Taylor 2007). 

The presence and diversity of trees is a distinguishing characteristic of this ecosystem. Trees affect 

productivity and diversity of montane plant communities more than in the other terrestrial CHDN 

ecosystems. The higher productivity of montane systems promotes the development of organic horizons 

in soils which, in turn, enhances water retention and availability to plants. The vertical structure of forests 

supports higher biomass than shrublands, and the heterogeneity of tree canopy enhances understory plant 

diversity and productivity. 

Because of cooler temperatures and more precipitation, surface water is often available longer in montane 

than in desert and foothill systems. Streams and springs are frequently the headwaters for aquatic systems 

at lower elevations. The health of montane aquatic systems is tightly linked to upland conditions. 

Sediment influx to streams is determined by upland soil stability and plant cover, and temperature 

regulation and nutrient input are mediated by riparian vegetation. Montane springs and seeps are isolated 

and provide habitat for rare and endemic plants or animals. 

Many animal species of this ecosystem are seasonal visitors, using resources for breeding during 

temperate warm months and migrating to other latitudes or altitudes during non-breeding periods. Some 

species, however, are resident. Black bears (Ursus americanus) in BIBE are residents of the Chisos 

Mountains and, although they also use some habitat types of the lower Foothills Ecosystem, this 

population is extremely isolated (Onorato et al. 2004). Mogollon voles (Microtus mogollonensis) and 

Mexican woodrats (Neotoma mexicana; Sullivan 1994) are notable residents of the montane system. 

Because of geographic isolation, resident species with limited reproductive rates or dispersal abilities are 

vulnerable to extirpation. Dynamics of isolated populations can be indicators of local (resource 

conditions) or regional (dispersal and recruitment) processes. Keystone species of the Montane 

Ecosystem have not been identified. However, montane environments often provide key or additional 

habitats for large carnivores which, in turn can limit effects of herbivores on vegetation (Schmitz et al. 

2000, White et al. 2003).
42 

GEOMORPHIC &

HYDROLOGIC CONDITIONS

landform, parent material, flow

channel, slope, aspect

determines base materials, flow 

direction, modifies radiation

NATURAL

DISTURBANCE

climatic extremes, floods, wildfire

initiates veg. succession, 

sediment and water pulses

REGIONAL CLIMATIC &

ATMOSPHERIC CONDITIONS

precipitation, wind, radiant energy, 

CO2, N2

provides thermal and chemical inputs, 

regulates ecosystem processes

1 2 4 SOIL RESOURCES

organic matter, minerals, 

water

nutrient & hydrologic cycling, 

faunal habitat

VEGETATION

plant patches to 

landscape cover

primary production, 

faunal habitat

FAUNA

functional groups, focal species

secondary production, 

predation, ecoengineering

CLIMATIC

CHANGE

increased temp.,

altered precip.

AIR POLLUTION

increased ozone,

N2, SO4

INVASIVE 

EXOTIC SPECIES

loss of natives, floral 

/ faunal disruption

HISTORIC LAND USEGRAZING, FIRE 

SUPPRESSION

increased erosion, 

changes in land cover 

and fauna

A B C A B 1 2 3

3 SPRINGS / STREAMS

water, sediment

hydrologic cycling, matter 

flow, biotic production, 

faunal habitat

4

RECREATION 

AND LOCAL USE

compaction, 

pollution, faunal 

disruption

C

High rates of tree 

mortality, Climate-induced 

changes in elevation

range of plant species

High rates of

tree mortality,

Acidification of 

aquatic resources

Exotic species 

invasion

High tree and shrub

densities

altered

hydrology

B altered

regimes

C

altered climatic,

atmospheric conditions

A

1 2 3 B 1 3 4 B C 1 2 3 4

Soil erosion, Exotic 

species invasion,

Pollution-mediated 

changes in aquatics

Figure 2.3.3. Ecosystem characterization model for the CHDN Montane Ecosystem. Solid ovals are drivers and interactive controls. Solid components that are interactive controls. Dashed rectangles are stressors, and dotted rectangles with blue text are key degradation proc

each stressor (described in Table 2.3.3). Text for interactive controls indicates components or structure followed by function. Text for streeffects.
43 

Interactions among increasing temperature, changes in the precipitation regime, and atmospheric 

pollutants are modeled to impact vegetation communities and disturbance regimes of montane systems. 

Higher rates of tree mortality, mediated by temperature-induced stress and foliar ozone damage, have 

implications for increased volumes of downed-woody fuels. Increased fuel loadings can support highseverity fires and lead to soil sterilization, an increase in water erosion of soils, and an overall reduction in 

site potential. Changes in soil properties from high-severity fires can alter post-disturbance successional 

development from the historical range of trajectories, with impacts to system function. Acid rain 

originating from nitrogen emissions can severely alter the chemistry of high-elevation aquatic resources 

and reduce biotic integrity of surface waters lower in the watershed. A potential consequence of climatic 

change is the alteration of bioclimatic zonation along elevational gradients (Ryan et al. 2008). It is 

possible that the climate envelope of CHDN montane species will move upward in elevation. The ability 

of individual species to track this change will determine degree of similarity in community composition 

between current and future montane systems. 

Similar to the other CHDN systems, recreational and local use of montane systems have the potential to 

pollute aquatic systems; physically alter vegetation characteristic of streams, springs, and seeps; and 

enhance the spread of exotic invasives. Soil compaction and erosion may occur in localized, over-used 

areas, but the deeper, well-developed soils are more resistant to trampling effects than in other terrestrial 

systems of the CHDN. 

Historical grazing and fire suppression have altered vegetation conditions and the fire regime. Previous 

grazing led to an increase in tree density by reducing competition between grasses and tree seedlings. 

Consumption of fine fuels by livestock also reduced the ability of ground fires to spread. Additionally, 

fire suppression since the 1920s has contributed to a significant reduction in fire frequency (Sakulich and 

Taylor 2007). With the removal of livestock grazing, enhanced conditions for the spread of fire and the 

increase in fuel loadings increases the risk of high-severity fires, with concomitant long-term impacts to 

soil stability, soil erosion, and changes in vegetation composition and structure. 

Five key degradation processes are predicted for the montane system (Figure 2.3.3, Table 2.3.3). All 

processes overlap with those of the Foothill Ecosystem. Exotic species invasion is included as a potential 

threat although the relative isolation of montane systems somewhat buffers against human-mediated 

introductions of exotics. 
44 

Table 2.3.3. Key degradation processes in the Montane Ecosystem, stressors and ecological 

effects associated with these processes, and potential measures that would characterize 

degradation processes and effects. 

Degradation process Stressors Ecological effects Potential measures 

Exotic species invasion Recreation and local 

use 

Plants: Altered nutrient 

dynamics, soil-water 

dynamics, major shift in 

functional-group structure 

Animals: Loss of native fauna 

Vegetative composition and 

structure, climatic-atmospheric 

elements, abundance of exotic 

animal species 

Soil erosion and 

redistribution 

Trampling by visitors, 

trespass grazing, air 

pollution, climatic 

change 

Erosion and loss of soil 

function due to reduction of 

biological soil crusts, soil 

compaction, soil-surface 

roughness, soil-aggregate 

stability, and water infiltration; 

decreased N fixation; 

changes in vegetative 

composition and structure 

Depth, structure, and stability of 

soils; biological soil crust cover 

and distribution; vegetative 

composition, structure, and 

pattern; climatic and atmospheric 

elements; trespass grazing 

Pollution-mediated dieoffs in aquatic systems Recreation and local 

use 

Altered biotic structure, 

composition, and function of 

aquatic systems 

Patterns of recreation use, water 

chemistry, aquatic biotic structure 

and composition 

Acidification of aquatic 

resources 

Acid rain (atmospheric 

nitrogen) 

Loss of native aquatic biota Water chemistry, aquatic biota 

structure and composition, 

atmospheric elements 

High tree density and 

high rates of tree 

mortality 

Fire suppression, 

climatic change, 

atmospheric pollutants 

Higher spatio-temporal 

frequency of snags and 

downed coarse-woody debris; 

larger contiguous fire patterns 

due to high fuel loads and fuel 

connectivity; erosion and loss 

of soil function due to 

sterilization, reduction in soil 

stability, reduction in site 

potential, and changes in 

attendant plant communities 

due to high-severity fire 

Fire regime attributes, tree 

mortality rates, tree and shrub 

structure and composition 
45 

2.3.4 Reservoir Ecosystem 

The CHDN Reservoir Ecosystem is International Lake Amistad and also includes the environments 

created by the confluence of three major rivers into Lake Amistad: the Rio Grande and the Pecos and 

Devils rivers (Figure 2.3.4). International Lake Amistad is a reservoir divided by the boundary of 

Coahuila, Mexico, and Texas, and has the second-largest drainage basin of any major reservoir in Texas 

(323,643 km2

). At its conservation elevation of 340.5 m above sea level, the reservoir has a mean depth of 

16.5 m. The entire reservoir system covers approximately 4% of the total CHDN area. The ecosystem 

characterization model for the Reservoir Ecosystem is shown in Figure 2.3.4, and discussed below. 

The four interacting drivers influence the water properties of reservoirs which, in turn, mediate the 

behavior of the four functional groups (Figure 2.3.4). Precipitation inputs to the reservoir occur as 

summer rains associated with the “Mexican monsoon.” Additionally, river flow and groundwater sources 

contribute to maintaining reservoir volume. The Edwards-Trinity Aquifer enters into the rivers near the 

reservoir and directly into the reservoir, and is especially important in maintaining reservoir water volume 

and quality, and buffering the variability of river flows. Variability of reservoir conditions over monthly, 

annual, and decadal spans is largely driven by climatic factors, such as hurricanes, drought cycles, and 

wet years. Surface geology, physiography, and topography within the watershed contribute to the 

transport of particulates and dissolved weathering products to the reservoir. Solar input and the movement 

of air masses are important for the mixing of dissolved gases and particulates throughout the water 

column. 

Bottom sediments form as particulates fall out of the water column. They contain high concentrations of 

bacteria and other decomposers that contribute to the energetics of the reservoir. Sediments found in 

deeper waters tend to become isolated from atmospheric gas exchange and, therefore, often become 

anoxic during periods of stratification. This results in low to very low redox (reduction-oxidation) 

conditions and the transport of nutrients and toxic materials (e.g., H2S, CH4, Fe, Mn, some heavy metals) 

into the overlying water column. The sediments also accumulate many pollutants that tend to be largely 

insoluble in water, such as the heavy metals and hydrophobic organic compounds. 

The water column consists of the complete body of water that fills the reservoir basin, and various 

physical, chemical, and biological components. Within the water column, the light environment, 

temperature, static and mobile layers of different density, dissolved electrolytes and non-electrolytes, 

nutrients, dissolved gases, and mixing pattern determine the structure and function of biological 

components. Phytoplankton, periphyton, and macrophyte communities are the sources of primary 

production, and drive the aquatic food webs of the reservoir. In the lacustrine zone of AMIS (main body 

of the reservoir), the water column has low phytoplankton biomass and nutrients, and this zone functions 

like an oligotrophic ecosystem (Groeger et al. in press). Nutrients and productivity are higher in the 

transitional zone, where riverine systems enter the reservoir. 

The shallow areas along the reservoir edge and inundation of riparian vegetation during high water levels 

form the reservoir’s littoral zone. These areas are extremely productive and serve as excellent habitat for 

vertebrate species because they provide cover (e.g., from predators for young and small fish) and high 

invertebrate biomass. As the reservoir refilled in 2003 and 2004, after 10 years of drought, vast areas of 

new, energy-rich habitat formed, proving a boon for the sport fishery. Littoral habitat is much better 

developed on the Rio Grande side of the reservoir than on the Devils River side. 

Reservoir fauna predominantly include fish and invertebrates, including zooplankton in the water column 

and benthos associated with deep-water sediments. Many fish species are not native to the Rio Grande 

and tributaries but are valued as a sports fishery (Appendix C). 
46 

Figure 2.3.4. Ecosystem characterization model for the CHDN Reservoir Ecosystem. Solid ovals are drivers and interactive controls. Solcomponents that are interactive controls. Dashed rectangles are stressors, and dotted rectangles with blue text are key degradation proc

each stressor (described in Table 2.3.4). Text for interactive controls indicates components or structure followed by function. Text for streeffects.

UPLAND 

WATERSHED CONDITIONS

landform, parent material, flow

channel, slope

shapes material flow and direction,

water quality

NATURAL

DISTURBANCE

climatic extremes, floods, wildfire

large inputs of sediment and water

REGIONAL CLIMATIC &

ATMOSPHERIC CONDITIONS

precipitation, wind, radiant energy, 

CO2, N2

provides thermal and chemical inputs, 

regulates ecosystem processes,

water quality

1 2 3 4

Reduced river flow 

rates, Siltation,

Salinization ,

Higher water

temperatures

Dewatering of

reservoir

Pollution-mediated 

die-offs, 

Bioaccumulation

of heavy metals

altered

conditions

c altered

regimes

D

altered climatic,

atmospheric conditions

A

HYDROLOGY

Stream, spring, groundwater

flow, river volume, and flow rate

material transport

and water quality

WATER COLUMN

organic matter, 

temperature, water

chemistry, plankton

nutrient cycling, faunal 

habitat, material transport

altered

hydrology

B

CLIMATIC

CHANGE

increased temp.

altered precip , 

increased 

variability in 

disturbance events

AIR POLLUTION

increased metals 

and pollutant 

loading

WATER POLLUTION

decreased water 

quality & biotic function, 

increased toxicity, 

community transition

INVASIVE 

EXOTIC SPECIES

loss of natives, floral 

/ faunal disruption

WATERSHED

DEGRADATION

increased erosion, 

sediment load, and 

material flow;

decreased water

flow

A 1 2 3 4 C 2 3 4

ALTERED 

HYDROLOGIC 

BUDGET

shifts many 

ecological process; 

community 

transitions

A B C D B 1 2 3 4 B D 1

Pollution-mediated 

die-offs, 

Bioaccumulation

of heavy metals

Exotic species

invasions

Dewatering of rivers, 

Siltation,

Salinization

SEDIMENT

quantity, chemistry, 

bacteria, benthos

respiration, 

water quality, nutrient 

and metal cycling

FAUNA

fish, invertebrates

primary & secondary 

production, predation,

biodiversity / interaction

LITTORAL & INUNDATED

RIPARIAN ZONE

water, sediment,macrophytes , 

and terrestrial plants

nutrient cycling and 

interchange, matter flow, 

biotic production

1 2 3 4 1 2 3 4
47 

Climatic change is a potentially important stressor that interacts with all four drivers of the system. With 

increasing air temperatures, the water column may become warmer in the winter and create a warmer 

hypolimnion during the summer, with an extended period of anoxia in this layer. Also, predicted increases 

in the variability of weather events, such as droughts and hurricanes, will add to the variability of river 

flow, littoral zones, reservoir water levels, and overall hydrologic conditions. Climate-induced stress of 

vegetation throughout the upland watershed has the potential to reduce soil-retention capacity and lead to 

higher sediment loadings of rivers and, eventually, the reservoir. Lower precipitation levels and increased 

temperatures have the potential to increase salinization of the rivers feeding the reservoir and, ultimately, 

increase the salinity of the reservoir. 

Pollutants and nutrients dumped directly into the source rivers and from the atmosphere, and in runoff 

from degradated uplands in the watershed, are threats to the quality of reservoir water. Sewage and other 

organics impact the reservoir through increased organic-matter loading, which leads to a higher oxygen 

demand and earlier (and more intense) anoxia in deeper waters. Eutrophication resulting from organic 

inputs also detracts from water clarity. Deposition of airborne heavy metals and volatile organics 

increases the toxicity of reservoir sediments and the bioaccumulation of toxic compounds throughout the 

food chain. Higher salinity levels in surface and groundwater due to agriculture, energy development, and 

urban centers impacts biotic integrity by killing native biota. Land uses within the watershed that 

accelerate erosion and transport of sediments may threaten to fill in the reservoir, impacting overall 

ecological integrity. 

The hydrologic budget in this system is most disrupted when water received from its upstream sources is 

less than water lost from the reservoir. This net loss of water effectively shrinks the ecosystem. A 

resulting decrease in water level and area can disrupt and, eventually, minimize function of the littoral and 

inundated riparian zones, shift turbidity fronts further toward the dam, and reduce faunal abundance. 

Invasive exotic species present a potential loss of biodiversity are a stressor that can change and degrade 

this ecosystem. Two examples include Hydrilla spp., an invasive rooted submergent macrophyte, and 

Prymnesium parvum, a toxic, brackish-water phytoplankton responsible for massive fish kills (also see 

Appendices C and I). 

Eight degradation processes are identified for the reservoir ecosystem (Figure 2.3.4, Table 2.3.4). 

Climatic change, air pollutants, and human-mediated changes in water quantity and quality throughout the 

watershed have the potential to degrade the integrity of the reservoir ecosystem. Exotic invasives, 

especially exotic aquatic plants, additionally can lead to large-scale die-offs of reservoir biota. 
48 

Table 2.3.4. Key degradation processes in the reservoir ecosystem, stressors and ecological 

effects associated with these processes, and potential measures that would characterize 

degradation processes and effects. 

Degradation process Stressors Ecological effects Potential measures 

Siltation (increase in 

sediment loading) 

Climatic change 

(extreme events), 

watershed degradation

Altered habitat structure; 

decreased productivity due to 

reduced light penetration; 

altered biotic structure, 

composition, and structure 

Water quality measures 

(dissolved oxygen, pH, specific 

conductance, fecal indicator 

bacteria, common dissolved 

inorganic constituents), 

abundance of biota, climate 

elements 

Salinization Climatic change, 

watershed degradation

Die-off of native biota not 

adapted to high salinity levels, 

reduced biotic integrity 

Climate elements, water quality 

measures, surface and 

groundwater flow rates, land-use 

activities, watershed condition 

Reduced river flow 

rates (reduced 

precipitation and 

dewatering of rivers) 

Climatic change, 

alteration of hydrologic 

budget by 

impoundments & 

water diversions, 

watershed degradation

Alteration of habitat structure 

due to reduced flow and 

reduced flow variability, 

reduced biotic integrity 

Climate elements, water quality 

measures, surface and 

groundwater flow rates, land-use 

activities, watershed condition 

High water 

temperatures 

Climatic change Increased respiration, lower 

dissolved oxygen, lower 

productivity 

Water temperature, water quality 

measures 

Dewatering of reservoir Altered hydrologic 

budget of reservoir 

(outflow exceeding 

inflow) 

Reduced spatial extent of 

reservoir ecosystem, lower 

abundance of biota, lower 

productivity, reduced biotic 

integrity 

Reservoir elevation, river flow 

rates, reservoir outflow rates 

Pollution-mediated dieoff Municipal and 

agricultural wastes, air 

pollutants 

Eutrophication, depletion of 

dissolved oxygen, altered 

structure and composition of 

biota 

Water quality measures, 

abundance of biota, atmospheric 

elements 

Bioaccumulation of 

heavy metals 

Airborne pollutants; 

runoff from 

agricultural, industrial, 

urban land uses 

Toxin-mediated 

malformations in higher 

trophic levels, die-offs of biota 

Atmospheric elements, water 

quality measures, heavy metal 

assay of higher trophic fauna 

Exotic species 

invasions 

Exotic aquatic plants 

and animals 

Altered biotic structure, 

composition, and function; 

altered ecosystem processes; 

toxin-induced mortality of 

native fauna 

Abundance of exotic plant and 

animal species 
49 

2.3.5 River Ecosystem 

There are three free-flowing rivers in the CHDN: the Pecos and Devils rivers and the Rio Grande. The 

Rio Grande flows through BIBE, RIGR, and AMIS. The Pecos joins the Rio Grande before flowing into 

Amistad Reservoir. Devils River flows into the reservoir. The River Ecosystem comprises approximately 

0.8% of the total area within CHDN. The ecosystem characterization model for the River Ecosystem is 

shown in Figure 2.3.5, and discussed below. 

Climate and atmosphere are key drivers of CHDN rivers. Solar energy drives seasonal and diel cycles. 

CHDN rivers lack extensive shading by trees, and solar input when a river is not turbid promotes high 

productivity. Precipitation drives fluvial geomorphic processes. Natural wet and dry seasons are typical, 

with highest flows from July through October (Huff et al. 2006). During monsoonal rains, river flow rates 

can quickly increase to a torrent, and rapid flows can be exacerbated by the funneling of waters by steep, 

constricted canyons. Large or sudden high-velocity inputs of water can alter river channels, transport 

large amounts of sediment, and ultimately rearrange deltaic deposits within Lake Amistad. Precipitation 

variability largely regulates the development of riparian zones, where low water levels during drought 

periods enhance riparian-zone development within river canyons. Because all three rivers flow into the 

Amistad Reservoir, water regulation of this reservoir also mediates water levels in the rivers and 

development of riparian areas. 

Upland watersheds influence water quantity and quality of CHDN rivers. Dissolved substances within the 

river are primarily formed from weathering of rock, or dissolution of rock and soil minerals in the 

uplands. High sediment inputs to the Rio Grande create turbid conditions, with light penetration less than 

1 m. The Pecos River is the most saline of the three rivers; salts are derived from contact with natural 

evaporate deposits. The Devils River is influenced by the weathering of limestone, and the salinity of this 

river is mediated by the saturation dynamics of inorganic carbon with limestone (Groeger and Gustafson 

1994). Disturbances, such as fire, can alter upland vegetative cover which, in turn, may increase runoff 

and sediment inputs to rivers. Such inputs may enhance structural complexity or degrade conditions for 

river biota, depending on the intensity and extent of the disturbance. 

The flow regime determines the mechanical forces that erode, transport, and deposit sediment and 

influence channel dimensions of river systems. Additionally, annual streamflow variation influences the 

occurrence of suitable habitat patches and species abundance (Auble and Scott 1998). Groundwater, 

surface springs, and surface runoff during storms are the water sources for the Pecos River and Rio 

Grande (Huff et al. 2006). The spring-fed Devils River is intimately linked with local groundwaters for its 

entire length. Especially in the Rio Grande, a higher volume of surface runoff contributes to higher 

variability in seasonal flows, which promotes spatial variability in in-stream structure and habitat for 

aquatic biota. 

The chemical and physical composition of the water column consists of (1) dissolved components of 

electrolytes (ions or salinity) and non-electrolytes (e.g., dissolved organic carbon [DOC] and silica); (2) 

particulate matter, including clays and other inorganic minerals (some will actually tend to be colloidal), 

non-living particulate organic carbon [POC], and organisms, mostly microscopic in nature (primarily 

bacteria and algae); and (3) gases, such as O2 and CO2. The amounts and distribution of these constituents 

in the water column define water quality and determine the ability of a river to support higher life forms. 

River sediment and substrate are composed of particles ranging in size from fine silt and clay particles to 

cobble, and ultimately to solid bedrock. Macrophytes, bacteria, algae, and other microbes form a biofilm 

on the sediment and substrate, and play a key role in river energetics (e.g., photosynthesis, respiration, 

nutrient uptake and transformation, and mineralization of detritus). The sediment and substrate may also 

be associated with a hyporheic zone, where surface and ground waters mix and where metabolic 

productivity and metabolism also may be quite high. 
50 

Figure 2.3.5. Ecosystem characterization model for the CHDN River Ecosystem. Solid ovals are drivers and interactive controls. Solid recomponents that are interactive controls. Dashed rectangles are stressors, and dotted rectangles with blue text are key degradation proc

each stressor (described in Table 2.3.5). Text for interactive controls indicates components or structure followed by function. Text for streeffects.

UPLAND

WATERSHED CONDITIONS

landform, parent material, flow

channel

shapes material flow and direction,

water quality

NATURAL

DISTURBANCE

climatic extremes, floods, wildfire

large inputs of sediment and water

REGIONAL CLIMATIC &

ATMOSPHERIC CONDITIONS

precipitation, wind, radiant energy,

N2

provides thermal and chemical inputs,

regulates ecosystem processes,

water quality

1 2 3 4

Dewatering, Siltation,

Terrestrilization

Dewatering, 

Siltation,

Terrestrilization

Pollution-mediated 

die-offs

altered

conditions

c altered

regimes

D

altered climatic,

atmospheric conditions

A

HYDROLOGY

Stream, spring, groundwater 

flow, river volume, and flow rate

material transport

and water quality

RIPARIAN ZONE

riparian plants, birds

nutrient cycling, material flow, 

biotic production, faunal habitat,

nutrient inputs to river systems 

FAUNA

fish, amphibians, 

invertebrates

secondary production, 

predation, biodiversity,

SEDIMENT, SUBSTRATE

FLOOD PLAIN SOILS

minerals, organic matter, 

micro-organisms

nutrient & hydrologic cycling, 

sediment storage, respiration, 

photosynthesis, habitat

WATER COLUMN

organic matter, 

temperature, water

chemistry, particulate 

matter

nutrient cycling, faunal

habitat, material transport

altered

hydrology

CLIMATIC

CHANGE

increased temp.

altered precip, 

increased

variability in 

disturbance events

AIR POLLUTION

increased material

and pollutant

loading

WATER POLLUTION

decreased water

quality & biotic function, 

increased toxicity, 

community transition

INVASIVE 

EXOTIC SPECIES

loss of natives, floral

/ faunal disruption

WATERSHED

DEGRADATION

increased erosion,

sediment load, and

material flow, 

decreased water

flow

A 1 2 3 4 4 C 2 3 4

ALTERED 

HYDROLOGIC 

BUDGET

shifts many

ecological process; 

community

transitions

A B C D 1 2 4 B 1 2 3 4 B D 3 B D 1

Pollution-mediated 

die-offs 

Exotic species

invasions,

Wildfire

Dewatering, 

Siltation, 

Terrestrilization
51 

The River Ecosystem provides habitat for two primary classes of fauna: macroinvertebrates (e.g., insects) 

and vertebrates (e.g., fish and amphibians). Macroinvertebrates are a vital link in river systems, as they 

consume algae and provide food for aquatic and terrestrial vertebrates. Macroinvertebrates respond to 

physical parameters, such as temperature, substrate, and current velocity, and also are influenced by the 

chemical environment, including pH, oxygen availability, and contaminates. In the Texas stretch of the 

Rio Grande, high water quality sites have higher diversity, and tend to be dominated by mayflies 

(Thraulodes, Travella, Choroterpes mexicanus, Tricorythodes) caddisflies (Cheumatopsyche, Hydroptila, 

Protoptila), and chironomids (Orthocladius, Cricotopus trifascia). Fish and amphibian species respond to 

water quality, form the higher tropic levels within rivers, and are a food resource for terrestrial 

vertebrates. Historically, the diversity of fish in the Rio Grande basin was high, and included a 

particularly rich minnow fauna (Dahm et al. 2005). Macroinvertebrates and fish are commonly used as 

biological indicators of River Ecosystem health (Karr et al. 1986, Barbour et al. 1999). 

The riparian zone functions as unique habitat and contributes disproportionately to conservation of 

biodiversity (Naiman et al. 1993). Native riparian plant communities of the southwestern U.S. provide 

feeding and breeding habitat for many migrating and resident bird species (Mills et al. 1991, Skagen et al. 

2005). Riparian zones are also important foraging habitat, and travel or dispersal corridors for many 

species of mammals (Ffolliott et al. 2004). During periods of drought, riparian zones may provide refugia 

habitat for some faunal populations. Riparian zones are a source of woody plant-material inputs to river 

systems. The decomposition of woody material by aquatic invertebrates adds nutrients to the aquatic 

system. Invertebrate populations, in turn, are an important food source for higher trophic fauna. Decreases 

in elevation of the Amistad reservoir water surface promote development of riparian vegetation along the 

extended upstream river corridor. In high-water years, re-inundation of the riparian zones creates river 

littoral zones that serve as important habitat for aquatic vertebrates and macroinvertebrates, and as 

sediment traps, both of which contribute to the productivity of this zone. 

Soils of riparian zones contain biota that contribute to the structure and functioning of riparian ecosystems 

by mediating nutrient cycling, water infiltration and storage, and nutrient uptake by plants. Functioning of 

these below-ground processes depends on the amounts and types of organic-matter inputs from vegetation 

and on soil conditions, such as soil aeration and soil temperature. 

Predicted changes in climate include increases in soil and air temperatures, altered precipitation patterns, 

lower snowfall and earlier snowmelt, and more variable and extreme climatic events (Solomon et al. 

2007). Recent studies (Milly et al. 2005, Seager et al. 2007) have specifically suggested increased aridity 

for the U.S. Southwest. Lower precipitation and runoff concentrates ions and may increase the salinity of 

the Rio Grande and Pecos River. Extended periods of drought can dry sections of a river, isolate 

populations of plants and animals, alter environments beyond physiological limits, and denude watershed 

vegetation. More intense storms can lead to excessive erosion, watershed degradation, flooding, river 

turbidity, reduced water quality, and lower productivity. 

Air pollutants emitted from industrial sources, such as the burning of coal, enter the water column of 

CHDN rivers. Compounds, such as mercury, lead, and cadmium, and strong acids can lead to widespread 

mortality of native flora and fauna. Nutrient additions, such as nitrogen deposition, can increase algae 

blooms with a subsequent decrease in light penetration and oxygen levels. A contemporary human health 

issue in the Rio Grande and Devils River arms of the Amistad reservoir is mercury concentration levels in 

sport fishes, such as largemouth bass (Becker and Groeger 2010). 

Human activities impact river systems through pollution and alteration of hydrologic budgets and 

watershed conditions. Municipal sewage discharge, industrial discharges, and nitrogen and phosphorus 

from agricultural runoff promote eutrophication and depletion of dissolved oxygen, which stress riverine 

biota. Impoundments, reservoirs, and irrigation reduce the amount (Gutiérriez et al. 2004) and variability 
52 

of streamflow, which can lead to dewatering of channels and floodplains, decreased bank stability, loss of 

riparian vegetation, increase in channel incision, increase in salinization, and overall degradation of water 

quality (Kelly 2001, Gutiérrez and Johnson in press) and habitat for aquatic organisms. In addition, water 

demand downstream from the Amistad reservoir can decrease reservoir surface elevation, which directly 

leads to a lengthening of the upstream river segments, exposes coves, and permits lateral littoral habitat to 

transition into riparian or terrestrial habitat. Land-management actions, such as rangeland agriculture, 

urban/exurban expansion (Purchase et al. 2001), timber extraction (Kelly 2001), mining, energy 

development, and the development of maquiladoras (affecting the Rio Conchos, the Rio Grande’s main 

Mexican tributary), alter surface runoff rates and sediment transport, add organic and metal contaminants 

to rivers, and reduce groundwater recharge and, thus, groundwater levels and streamflow. Alteration of 

upland fire regimes through fire suppression or conversion to high-biomass conditions increase the risk of 

extensive, high-severity wildfires that can result in large-scale soil erosion, transport, and sediment 

loading to rivers. Overall, human-mediated changes to the Rio Grande have reduced the diversity of the 

benthic community (Dahm et al. 2005), reduced populations of uniononid mussels (Dahm et al. 2005), 

and led to the extirpation of a number of fish species, with 12 other fish species being listed as species of 

conservation concern (Purchase et al. 2001). 

Exotic species invasions can lead to major changes in community composition, competitive displacement 

of native species, and alterations of ecosystem-level properties, such as disturbance regimes (D’Antonio 

and Vitousek 1992, Mack and D’Antonio 1998) and soil-resource regimes (Vitousek 1990). Invasive 

exotic species of concern in CHDN river systems include salt cedar (Tamarix spp.) and giant reed 

(Arundo donax) in the riparian zones (Purchase et al. 2001), Asian clam (Corbicula fluminea) and nutria 

(Myocastor coypus), and, in the Pecos River, the toxic alga, Prymnesium parvum (Appendices D and E).

Tamarisk is of special concern because it can promote fire disturbance by producing large numbers of 

dead stems. Higher fire frequency can lead to erosion, temperature increases, and altered flow rates. Ash 

from fires can increase nutrients, ions, turbidity, and pH, and decrease oxygen levels of aquatic systems. 

Six critical degradation processes are identified for river systems (Figure 2.3.5, Table 2.3.5). Climatic 

change, air pollutants, and human-mediated changes in in-stream flow rates and sediment inputs alters instream habitat structure, decreases productivity, alters biotic composition, and can lead to the loss of 

riparian zones. Organic and inorganic pollutants can severely alter productivity and directly kill aquatic 

organisms. Exotic plants, especially, have the potential to alter wildfire regimes with concomitant impacts 

to riparian zones and stream nutrient and sediment loadings. 
53 

Table 2.3.5. Key degradation processes in the River Ecosystem, stressors and ecological effects 

associated with these processes, and potential measures that would characterize degradation 

processes and effects. 

Degradation process Stressors Ecological effects Potential measures 

Siltation (increase 

sediment loading ) 

Climatic change 

(extreme events), 

watershed degradation

Altered in-stream habitat 

structure; decreased 

productivity due to reduced 

light penetration; altered biotic 

structure, composition, and 

structure 

Water quality measures 

(dissolved oxygen, pH, specific 

conductance, fecal indicator 

bacteria, common dissolved 

inorganic constituents), 

abundance of biota, climate 

elements 

Dewatering (decrease 

stream flow & increase 

in salinization) 

Climatic change, 

alteration of hydrologic 

budget by 

impoundments & 

water diversions, 

watershed degradation

Alteration of in-stream habitat 

structure due to reduced flow 

variability, salinity-induced 

changes to biota 

Climate elements, water quality 

measures, surface and 

groundwater flow rates, land-use 

activities, watershed condition 

Terrestrialization 

(invasion of riparian 

zones by upland 

vegetation) 

Climatic change, 

alteration of hydrologic 

budget by 

Impoundments & 

water diversions, 

watershed degradation

Conversion of riparian 

vegetation with upland or 

xeroriparian species due to 

reduced water availability 

Climate elements, surface and 

groundwater flow rates, riparian 

vegetation structure and 

composition, land-use activities, 

watershed condition 

Pollution-mediated 

die-off (organic, 

inorganic pollutants) 

Municipal and 

agricultural wastes, air 

pollutants 

Eutrophication, depletion of 

dissolved oxygen, altered 

structure and composition of 

biota 

Water quality measures, 

abundance of biota, atmospheric 

elements 

Exotic species 

invasions 

Exotic invasives Altered biotic structure, 

composition, and function; 

altered ecosystem processes 

Abundance of exotic plant and 

animal species 

Wildfire Exotic plant invasions 

of riparian zones 

Alteration of fire regime with 

higher frequency and severity 

of wildfires; increase in ash, 

nutrient, and sediment inputs 

to river systems during fire 

events resulting in alteration 

of lotic productivity and biotic 

composition 

Abundance of exotic riparian 

plants, fire regime attributes 
54 

2.3.6 Dune Ecosystem 

The Dune Ecosystem comprises 6.2% of the total park area in CHDN, but is restricted to two areas with 

ancient lake beds in the Tularosa Basin, New Mexico, and the Salt Flat, Texas. The dunes at WHSA are 

composed almost entirely (99%) of gypsum, while the dunes at GUMO include some dominated by 

gypsum with a carbonate content and others composed of quartz sand (Wilkins and Currey 1999). Dune 

fields originated from prehistoric lakes that repeatedly dried up under warmer climates and eventually 

produced an abundant source of eolian sand that formed the dune fields observed today (Allmendinger 

1972, Wilkins and Currey 1997, Langford 2003). The ecosystem characterization model for the Dune 

Ecosystem is shown in Figure 2.3.6, and discussed below. 

Precipitation has an indirect influence on dunes through the recharge of groundwater which, in turn, is a 

key driver of dune dynamics (described below). Precipitation in the dune fields is generally low (20.3–

30.5 cm/8–12 in), and highly variable in amount and timing among years and seasons. Recharge generally 

occurs during spring storms, and with the monsoonal rains of late summer and early fall (Crabaugh 1994, 

Langford et al. 2009). Precipitation influences depth to groundwater and salinity, both of which influence 

dune stability. In years with high rainfall, active dunes can be partially stabilized by dilution of otherwise 

saline groundwater. Periods of high precipitation and recurrent flooding can cause eolian aggradation of 

the interdunes (Kocurek 2007). 

Groundwater hydrology is a key element in creating and maintaining the gypsum dune field in WHSA. 

Groundwater brines leaching from bedded evaporites are likely important sources of gypsum (McLean 

1970, Allmendinger 1972, McLean 1975, Myers 1983, Cruz 1985, Myers and Pinckley 1987, Sutton et al. 

1988, Myers and Sharp 1989; 1992, Basabilvazo et al. 1994, Langford, 2003). Evaporation at the surface 

drives wicking of saline water from the shallow water table, 1–3 m below the surface (Allmendinger 

1972). Gypsum crystallizes as a powdery efflorescence on the surface and as small crystals at and below 

the surface but above the water table (Allmendinger 1972). The gypsum that makes up the bulk of the 

extant dunes was derived from deflationary episodes, when large areas of the present-day salt flats were 

excavated during prolonged droughts. High groundwater salinity influences dune stability by inhibiting 

vegetation growth (Langford et al. 2009). Older dunes are vegetated and stable, and portions of WHSA 

dunes are estimated to have been stable for at least 3,400 years (Langford et al. 2009). 

Winds determine the movement of sand across the dune fields (Fryberger 1979, Frank 1994, Frank and 

Kocurek 1994; 1996, Fryberger 2003). At WHSA, dominant winds from the west-southwest transport 

sand to the northeast across the dune field. Frank (1994) and Frank and Kocurek (1994; 1996) correlated 

local sand transport and wind velocities to the elevations on dunes, finding that sand transport was highest 

at the tops of the dunes. The parabolic dunes and active dune sand areas migrate continuously, and 

extreme wind events accelerate their movement. The parabolic interdunes and vegetated dune areas are 

stable and sufficiently vegetated that extreme wind events result in little to no dune movement. 

Floods and droughts can mediate dramatic changes to dunes. If flood waters remain fresh or brackish, 

they may result in expansion of vegetation within interdunes and the stabilization of migrating dunes 

(Langford et al. 2009). On the other hand, if fresh water is mixed with saline groundwater and becomes 

toxic for the local vegetation, then loss of vegetation and expansion of the migrating dunes may result 

(Langford et al. 2009). Extended droughts may have the most significant impacts. The geologic record 

shows that the various parts of the dune field were formed rapidly during short, hyperarid events. A 

prolonged, significant drop and subsequent loss of available water may result in mobilization of the 

parabolic interdunes and other areas that are currently stable in the park. 
55 

Figure 2.3.6. Ecosystem characterization model for the CHDN Dune Ecosystem. Solid ovals are drivers and interactive controls. Solid re

components that are interactive controls. Dashed rectangles are stressors, and dotted rectangles with blue text are key degradation proceach stressor (described in Table 2.3.6). Text for interactive controls indicates components or structure followed by function. Text for streeffects.

GEOMORPHIC &

HYDROLOGIC CONDITIONS

landform, parent material, flow

channel

determines base materials, flow

direction, modifies radiation

NATURAL

DISTURBANCE

climatic extremes, floods

dune movement, large 

inputs of water

REGIONAL CLIMATIC &

ATMOSPHERIC CONDITIONS

precipitation, wind, radiant energy, 

CO2, N2

provides thermal and chemical inputs, 

regulates ecosystem processes

1 2 3 4

Decrease in plant cover Exotic species

invasion

Increase depth to

groundwater, Increase 

salinity of groundwater

altered

hydrology

B altered

regimes

C

altered climatic,

atmospheric conditions

A

GEOLOGY & LANDFORM

sources of Ca and SO 4, faulting, 

basin playa

mineralization and setting

for sand formation

FAUNA

functional groups, focal species

secondary production, 

predation, color morphing /

adaptation, biodiversity

VEGETATION

Biocrust, plant patches to 

landscape cover

primary production, 

faunal habitat, dune

anchoring and stability

SOIL RESOURCES

organic matter, minerals, 

moisture

nutrient & hydrologic

cycling, plant production, 

faunal habitat

MIGRATING

DUNES

gypsum fields, inter -

dune hollows

hydrologic cycling, matter

flow, soil stability, 

ecosystem extent

INVASIVE 

EXOTIC SPECIES

loss of natives, floral

/ faunal disruption,

dune stabilization

ADJACENT

GROUNDWATER

WITHDRAWAL

dune formation 

and dynamics

B 1 2 3 B C 1 2 3 4

Increase depth to 

groundwater, Increase

salinity of groundwater,

Decrease in plant cover

CLIMATE 

CHANGE

increased

temperature,

altered

precipitation,

extended drought

A B C

AIR POLLUTION

increased ozone,

N2, SO4

A 1 2 3
56 

Quaternary and Holocene landforms are responsible for the current distribution of dunes (Fryberger 

2003). At WHSA, the older dunes currently occupy a topographic high that was an island in a lake that 

covered the landscape between 12,000 and 38,000 years ago (Seager et al. 1987, Fryberger 2003). The 

main dune field now occupies what was the lake floor at that time. This pluvial lake (Lake Otero) formed 

under a cooler, wetter climate, when inflow from the surrounding mountains exceeded outflow to the 

groundwater. A similar pluvial lake, Lake King, covered a large part of the present-day gypsum dune 

field at GUMO (Wilkins and Currey 1997). The dune fields of WHSA and GUMO are currently 

migrating across a stepped landscape, with the ancient shorelines marking the steps. These steps also 

mark changes in groundwater salinity (Langford et al. 2009), sulfur isotopes (Szynkiewicz et al. 2007), 

and dune morphology (Kocurek et al. 2007, Langford et al. 2009). 

The gypsum dune fields at WHSA and GUMO can be divided into three general classes (or system 

states): older dunes, parabolic dunes, and active dune areas. Stable dunes, some of which may be older 

than 16,000 years, result from the accumulation of soil and subsequent establishment of vegetation 

(Fryberger 1979; 2003). Biological soil crusts are a component of older dunes (Johansen 1993, Kidron 

and Monger 2001, Trujillo et al. 2007), and serve to stabilize the soil (Kidron and Monger 1999), retain 

soil moisture (Kidron and Monger 2001), and fix nitrogen (Shields 1957, Johansen 1993). A savanna 

grassland on these dunes is dominated by alkali sacaton (Sporobolis airoides), gyp grama (Bouteloua 

breviseta), little bluestem (Andropogon scoparius), and sandhill muhly (Muhlenbergia pungens). The 

parabolic dune areas consist of active patches of gypsum dunes that are migrating through a hummocky, 

vegetated duneland that covers the largest area in both parks. The boundaries between parabolic and older 

dune areas are sharp and coincide with vegetation and soil changes. Active portions of the parabolic dune 

type can support scattered shrubs (Reid 1979, Patrick 1980, Patrick and Reid 1980). Active dune areas are 

found only at WHSA, and are essentially unvegetated and consist of blowing, loose eolian sand dunes 

separated by partially vegetated to unvegetated flats (Langford 2003). The substrates and landforms of 

these three classes of dunes are similar. The changes in state between the active dunes, the parabolic 

dunes, and the older dune areas are a function of differences in vegetation, soil, and hydrology. 

Plant speciation has occurred in connection with the limiting edaphic conditions of gypsum soils (Powell 

and Turner 1977). Land-use changes outside protected dune areas, and the limited extent of dune systems, 

have resulted in a number of endangered, threatened, rare or sensitive plants being located in the CHDN 

Dune Ecosystem. These include grama grass cactus (Toumeya papyracanthus), Roetter’s hedgehog cactus 

(Echinocereus X roetteri), button cactus (Epithelantha micromeris), gypsum milkvetch (Astragalus 

gypsodes), Burgess’ broomsage (Lepidospartum burgessii) and Warnock’s groundsel (Senecio warnockii) 

(Northington and Burgess 1979, Guadalupe Mountains NP 2005). Other plants of special status are 

Guadalupe rabbitbrush (Chrysothamnus spathulatus), gypsum blazingstar (Mentzelia humilis), and 

gypsum ringstem (Anulocaulis gypsogenus). 

The gypsum dunes provide a unique template for the evolution and adaptation of a number of faunal 

variants. Notably found within WHSA are toads, lizards, snakes, insects, and rodents that have developed 

white coloration to blend with the white gypsum sands (Benson 1932, Blair 1941, Stroud and Strohecker 

1949, Hager 2002, Rosenblum 2005; 2006). Eric Metzler (Research Entomologist, pers. comm.) estimates 

that more than 1,000 species of Lepidoptera (butterflies and moths) inhabit WHSA, and researchers have 

discovered more than a dozen species of moths there that are new to science. The only endemic fish 

known in the Tularosa Basin, the White Sands pupfish (Cyprinodon tularosa), occurs in one waterway in 

the dunes of WHSA during high water flows (Pittenger and Springer 1999), and is a State Threatened 

Species in New Mexico. 

Climatic change is modeled to influence groundwater quantity and salinity levels, and eolian processes. 

Two recent studies (Milly et al. 2005, Seager et al. 2007) have suggested increased future aridity for the 

U.S. Southwest. With frequent, prolonged periods of drought, the depth to groundwater may increase, 
57 

especially in conjunction with greater groundwater pumping on adjacent lands. Similarly, salts may 

become more concentrated, affecting dune movement. Short-term weather patterns that result in greater 

wind velocities may change the dynamics of sand transport and dune distribution. Increased temperatures 

and periods of drought, in addition to foliar damage by ozone and other air pollutants, may decrease plant 

cover and destabilize dunes. 

Urban and agricultural areas near the WHSA and GUMO dune fields typically harvest groundwater for 

life requisites and food production, respectively. Use of groundwater has increased in the Tularosa Basin 

(WHSA area) with modest development. The rapid growth of El Paso, Texas, may also require 

groundwater mining west of GUMO in the near future. Lowering of the groundwater table and an 

increase in salinity have the potential to mobilize the gypsum dunes. Migrating dunes bury dunestabilizing vegetation, creating a positive feedback loop that can perpetuate dune instability and 

movement. 

Exotic plants are of particular concern in dune systems. Exotic species, such as salt cedar (Tamarix 

gallica), Russian thistle (Salsola kali var. tenuifolia), and African rue (Peganum harmala) (Appendices C 

and D) are present in WHSA or GUMO. Invasive plant species can stabilize dunes and eventually shift 

function and interactions within biological communities. Loss of some native plant species may result in 

loss of unique variants of pollinators or other insects. In high abundance, some invasive plants can alter 

local hydrology. Water consumption by salt cedar, especially, has the potential to severely impact the 

Dune Ecosystem (Zavleta 2000). One acre of salt cedar uses about 7.7 acre feet of water annually, or 2.8 

million gallons (Carmen and Brotherson 1982, Davenport et al. 1982, Hart 2004). WHSA has over 3,000 

ac of salt cedar, equaling a possible water loss of 23,100 acre feet each year. Because dune stability is 

enhanced by a high water table, high densities of salt cedar would destabilize dunes. 

Four key degradation processes are predicted for dune ecosystems (Figure 2.3.6, Table 2.3.6). Climatic 

change, groundwater withdrawal on adjacent lands, and exotic plants are predicted to increase the salinity 

and depth of groundwater. Temperature and moisture-induced stress under climatic change may lead to 

higher plant mortality in this xeric system. All processes have the potential to affect stabilization of dunes. 
58 

Table 2.3.6. Key degradation processes in the Dune Ecosystem, stressors and ecological effects 

associated with these processes, and potential measures that would characterize degradation 

processes and effects. 

Degradation process Stressors Ecological effects Potential measures 

Increase depth to 

groundwater 

Climatic change, 

exotic plant invasion, 

groundwater 

withdrawal on adjacent 

lands 

Altered soil-water dynamics 

leading to decrease in dune 

stability 

Groundwater quantity and quality 

measures, land use related to 

water extraction on adjacent 

lands, abundance of exotic 

species, climatic elements 

Increase salinity of 

groundwater 

Climatic change, 

exotic plant invasion, 

groundwater 

withdrawal on adjacent 

lands 

Altered soil-water dynamics 

leading to decrease in dune 

stability 

Groundwater quantity and quality 

measures, land use related to 

water extraction on adjacent 

lands, abundance of exotic 

species, climatic elements 

Exotic species 

invasion (plants) 

Exotic plant invasion Altered soil-water dynamics 

leading to decrease in dune 

stability, increase in dune 

stability where water table is 

unaffected, shift in functionalgroup structure 

Vegetation composition and 

structure, climatic and 

atmospheric elements 

Decrease in plant 

cover 

Climatic change, air 

pollution 

Altered soil stabilization 

properties leading to 

decrease in dune stability, 

altered biotic integrity with 

decrease in plant cover 

Vegetation composition and 

structure, climatic and 

atmospheric elements 
59 

Chapter 3: Vital Signs 

3.1 Introduction 

“Vital Signs” are a subset of physical, chemical, and biological elements and processes of park 

ecosystems that are selected to represent the overall health or condition of park resources, known or 

hypothesized effects of stressors, or elements that have important human values. The elements and 

processes that are monitored are a subset of the total suite of natural resources that park managers are 

directed to preserve unimpaired for future generations, including water, air, geological resources, plants 

and animals, and the various ecological, biological, and physical processes that act on those resources 

(http://science.nature.nps.gov/im/monitor/glossary.cfm). 

This chapter describes the core set of 21 vital signs identified for the CHDN, the process used to identify 

these vital signs, their relationships in the conceptual models, and the subset of core vital signs that will 

be implemented with current funding. 

3.2 Overview of Vital Signs Selection Process 

The focus of the CHDN is on attaining network-wide inference for most of our vital signs. The network 

developed its prioritized list of vital signs through a multifaceted process that involved interviews of park 

staff and non-park staff intimately familiar with specific park issues, park-based scoping meetings, topicspecific workshops, online web ranking, vital signs prioritization workshops, conceptual model 

development, and meetings with Technical Committee members and the Board of Directors (Table 3.2). 

The network took a multi-step approach to identify, prioritize, and select vital signs. This step-wise, 

iterative process allowed various ecological indicators to be compared and collectively selected for 

inclusion in the network’s vital signs monitoring program. An overview of the steps used for the selection 

of CHDN vital signs is listed below. Note that due to certain logistical constraints, we did not necessarily 

follow these six steps in sequential order. 

1. Conduct a series of interviews and small, park-based workshops to identify important resources 

(abiotic, biotic, processes), resource threats, stressors, management concerns, potential 

monitoring questions, and vital signs for each network park. 

2. Identify similarities and differences across parks and summarize vital signs, threats, management 

concerns, and monitoring questions at the network level. 

3. Prioritize vital signs for each park based on management and ecological significance and legal 

mandate. 

4. Identify ecosystem drivers, stressors, and important processes through development of initial 

conceptual ecological model for the network’s ecosystems. 

5. Conduct a network-level vital signs workshop to complete scientific review of network-level vital 

signs and associated information; complete prioritization of vital signs based on ecological 

significance and justification from scientific literature or other models; provide additional 

information helpful to monitoring high-priority vital signs (e.g., partnership opportunities, 

monitoring objectives). 
60 

Table 3.2. Events and associated outcomes in the steps followed to identify and prioritize CHDN 

vital signs. 

Date Event Steps taken Outcome/Product 

Dec. 2004–Mar. 2005 Scoping meetings at each 

park. 

“Laundry list” of potential vital signs 

generated at each park. 

Parks focus on vital 

signs selection 

process. 

Jun. 2005 Intranet web-based 

ranking of 145 non-unique 

vital signs by park 

resources staff & 

superintendents. 

Produced candidate list of vital 

signs to move forward in the 

prioritization & selection process. 

Potential set of vital 

signs reduced to 97. 

Oct. 2005 Water Quality & Water 

Resources Workshop. 

Further refined water resources 

related vital signs. 

See Appendix I, Table 

I.1-1. 

Jun. 2006 Chihuahuan Desert 

Network Prioritization 

Workshop (CHDN-PW). 

Reviewed and scored 97 unique 

vital signs. 

See Appendix I, Table 

I.2-1. 

Jul. 2006 Technical Committee 

provides management 

significance scores for 

new and renamed vital 

signs from (CHDN-PW). 

New vital signs fully scored and 

ranked. 

Generated list of 36 

high-priority vital signs 

(see Appendix I, Table 

I.2-3). 

Aug. 2006 Technical Committee & 

Board of Directors meets 

to review 36 high-priority 

vital signs prioritization 

and selection process. 

Vital sign prioritization selection 

process and high-priority list of 36 

vital signs unanimously supported 

by the Technical Committee and 

Board of Directors. 

High-priority vital signs 

list accepted, network 

moves forward with 

monitoring plan 

development. 

Aug. 2006 Request to add two vital 

signs. 

TC/BOD discussions with park staff 

about vital signs lead to request. 

High-priority list 

increased to 38 vital 

signs. 

Sep. 2006–Feb. 2007 Development of framework 

for seven proposed 

monitoring protocols 

collapsing 38 high-priority 

vital signs down to 28. 

Discussions and approvals by 

Technical committee and Board of 

Directors on final 28 vital signs. 

New list of 28 vital 

signs grouped into 

seven protocols 

accepted. 

July–Nov. 2007 Teleconference with 

Carlsbad Caverns NP 

resources staff and 

outside cave experts; and 

with ARD on use of lichens 

& mosses vital signs. 

Discussion on cave-related vital 

signs and potential duplication with 

park-specific cave management 

and monitoring plan. Discussion 

and additional research into nature 

of use of lichen as air-quality 

biomonitors in arid lands lead to 

decision by CHDN to eliminate this 

vital sign from consideration. 

Cave-related vital 

signs monitoring 

relinquished to park 

staff. Biomonitoring 

vital sign eliminated 

from further 

consideration. 

July 2007–Mar. 2008 Various cooperators 

independently work on 

Protocol Development 

Summaries (PDS). 

PDS written for the seven 

monitoring protocols that includes 

25 CHDN vital signs. 

25 core vital signs 

make up CHDN 

monitoring program. 

June–Dec. 2008 Review and finalize list. CHDN Vital Signs Plan reviewed by 

Technical Committee, Board of 

Directors, external reviewers, and 

WASO. 

Core vital signs 

reduced to 21; 

additional PDS 

written. 
61 

6. Conduct meetings with network, parks, and CHDN Technical Committee to select a final list of 

high-priority and core vital signs for the CHDN parks. The outcome is reviewed and concurrence 

given by the Board of Directors. 

Park- and network-level workshops and meetings were held for the CHDN from 2004 to 2007. The 

outcomes of key workshops and meetings are summarized in the next sections. 

3.2.1 Park-level vital signs scoping workshops (2004–2005) 

During December 2004–March 2005, the network conducted park-level vital signs scoping workshops at 

AMIS, BIBE (including RIGR), CAVE, FODA, GUMO, and WHSA. The purposes of those workshops 

were to present the vital signs program to all interested park staff and receive staff input on potential vital 

signs for the park and network. The objective of the workshop was to identify important park resources 

and management issues, park drivers and stressors, potential park monitoring and research questions, and 

candidate vital signs. To prepare for these park-level workshops, network staff summarized priority 

resources, stressors, and resource concerns using General Management Plans, Resource Management 

Plans, and available Geologic Scoping Workshops. Network staff also conducted one-on-on interviews 

with park staff, including superintendents. Interviews followed up on responses submitted from a 22-item 

questionnaire (Appendix G). 

Participation in most workshops ranged from 10 to 20 individuals representing park and network staff and 

park cooperators/scientists. Candidate vital signs at the park level were identified within six broad 

categories: Air/Climate, Geology/Soils, Water, Biota (Animals and Plants), Human Use, and Ecosystem 

Pattern and Processes. For each category, participants identified specific resources and resource issues 

important to their park. Responses ranged from small-scale, discrete resources (e.g., Guadalupe 

Mountains violet) to broad-scale ecosystem processes (e.g., geomorphic processes), and resources of 

value for societal reasons (e.g., soundscapes, viewscapes). Responses were directly recorded into a 

database to simplify the evaluation and analysis process. 

For each resource, park staff identified associated ecosystem stressors, specific threats, management 

concerns, and potential monitoring questions. Following all park-level scoping workshops, each park’s 

vital signs were uploaded into a CHDN database. This database included 145 non-unique candidate vital 

signs. CHDN staff designed an online, web-based application that allowed park resources staff and 

superintendents to score these 145 non-unique vital signs based on three criteria: ecological significance 

(50%), legal mandate (15%), and management significance (35%). This list included duplications. 

Individual, park-level databases were merged into a single, network-level database. After scores were 

tallied, a list of 97 unique vital signs was used to develop a vital signs framework for the network. 

3.2.2 Network-level vital signs prioritization workshop (2006) 

On June 14–15, 2006, the network-level vital signs prioritization workshop was held in El Paso, Texas, to 

(1) review identified management and scientific issues, resource threats, and monitoring questions; (2) 

review, revise, and prioritize candidate vital signs for long-term ecological monitoring at the network and 

park levels; (3) revise justification statements, develop potential monitoring objectives, identify existing 

protocols/methods, potential partnerships, cost-sharing opportunities, and ecological/operational scales 

for measurement for the top 25% of vital signs; and (4) develop a network of stakeholders with the 

common goal of preserving important network resources. Sixty-four individuals from more than 30 

organizations participated in the workshop, including representatives from federal and state agencies, 

academic and research institutions, and non-profit organizations. 

Based on the participants’ expertise, they were assigned to one of five breakout groups: (1) Animals, (2) 

Aquatic Resources and Water Quality, (3) Landscape, (4) Plants and Soils, or (5) Unique Systems (Caves 

& Dunes). Each work group reviewed a specific set of candidate vital signs and was assigned a facilitator, 
62 

recorder, and at least one park staff member with appropriate expertise to facilitate workflow and capture 

workshop results in an MS Access database. Ninety-seven unique vital signs from the park-based scoping 

meetings were evaluated by relevant ecosystem, based on justification source and ecological significance 

score (Table I.1-1 in Appendix I). After individual work groups presented their results, the groups 

reconvened to conduct the overall prioritization of vital signs. Following the workshop, the Technical 

Committee scored all new vital signs generated from the workshop for management significance. These 

scores were added into the scores generated from the prioritization workshop. 

After the vital signs prioritization workshop, CHDN staff evaluated existing and new vital signs from the 

five breakout groups, performed additional analysis of the vital signs generated by the workshop, and 

reduced the lists generated by the work groups to a more integrated, defined a set of 86 unique candidate 

vital signs that were fully scored and ranked (Table I.2-3 in Appendix I). We then separated the scored 

vital signs by ecosystem and generated rank score diagrams (Tables I.6–12 in Appendix I). Based on 

scores and diagrams, we identified high-priority vital signs from each ecosystem, resulting in a list of 36 

high-priority vital signs. The 2006 CHDN Vital Signs Prioritization Workshop Report can be found in 

Appendix I. 

The CHDN Technical Committee and Board of Directors met in August 2006 to discuss the vital signs 

process, conceptual models, candidate list of high-priority vital signs, and vital signs to be retained for 

development in the monitoring plan. High-priority vital signs were identified based on a review of the 

prioritized network list. The Technical Committee also discussed vital signs ranked highly at the park 

level but not at the network level and made decisions based on management and ecological significance, 

potential partnership and cost-sharing opportunities, and existing baseline data. At this meeting, no 

additional vital signs from the set of 86 vital signs were brought forward for inclusion in the high-priority 

list of 36 vital signs. 

The Technical Committee agreed that given budgetary constraints, only a small subset of vital signs could 

be monitored over the long term. Nevertheless, the Technical Committee did not want to constrain the 

final list of core vital signs. They expressed that a spirit of cooperation with park resource staff and 

members of the scientific community, along with information from additional models and scientific 

literature, should determine final vital signs for monitoring. 

The Board of Directors reviewed and discussed the Technical Committee’s recommendations, the list of 

86 candidate vital signs, and the subset of 36 high-priority vital signs. The Board of Directors expressed 

confidence in the process. The Board felt the high-priority list was comprehensive and strongly reflected 

indicators that should assist them and their staffs in resource management. The Board unanimously 

concurred with the Technical Committee’s recommendations and voted to adopt the list of 36 highpriority vital signs. 

During the ecological modeling process, two additional vital signs, distribution and abundance of 

heteromyid rodents and geomorphology of river channels, were added, reviewed, and approved, bringing 

the total number of high-priority vital signs to 38. 

3.2.3 Selection of core vital signs (2006–2008) 

During the last phase of review and refinement, consideration was given toward practical implementation 

of the CHDN monitoring program. Given that funds for monitoring will have limits, vital signs were 

grouped in such a way as to maximize information gain for the types of effort and costs that would need 

to be expended. A conscious decision also was made to select vital signs of common concern, rather than 

park-specific in nature. Thus, the final list is relevant to most of the parks. 
63 

In meetings and discussions with the Technical Committee and Protocol Development Summary authors, 

the criteria used to select core vital signs included: 

 Opportunities to collaborate (e.g., TCEQ, park monitoring, International Boundary and Water 

Commission) 

 Opportunities in which co-location or other techniques (similarity in sampling and measurement 

requirements) could reduce costs 

 Suites of indicators that, when monitored together synergistically, add value by providing greater 

information for improving ultimate interpretation of monitoring trends 

 Low-cost indicators that could be accomplished with little additional funding despite ranking 

slightly lower than more expensive indicators 

This evaluation led to a final set of 21 core vital signs that could be monitored under seven umbrella 

protocols. After the list was adjusted a bit to better coordinate with the servicewide I&M program, the 

number of monitoring protocols was expanded from seven to eleven to improve clarity. Table 3.2.3 shows 

the final set of core vital signs within the context of the NPS Ecological Monitoring Framework, a 

system-based, hierarchical outline that facilitates comparison of vital signs among parks, networks, and 

other programs. 
64 

Table 3.2.3. Chihuahuan Desert Network core vital signs, presented by park and funding category within the conteEcological Monitoring Framework. 

Parks where implemented/

LEVEL 1 LEVEL 2 LEVEL 3 CHDN vital sign 

AMIS BIBE CAVE FODA 

Ozone Ozone ◊ ◊ Wet and Dry Deposition Wet and Dry Deposition ◊ 

Air Quality 

Visibility and Particulate Matter 

Visibility and Particulate Matter ◊ 

Air and Climate 

Weather/Climate Weather/ Climate Basic Meteorology ◊ ◊ ◊ ◊ 

Windblown Features and Processes 

Dune Formation and Stability 

Windblown Features and Processes Dune Morphology 

Geomorphology 

River Channel Characteristics 

River Channel Characteristics ● ◊ 

Soil Hydrologic Function ● § § § Biological Soil Crusts § § § Soil Erosion (Wind and Water) § § § 

Geology and Soils 

Soil Quality Soil Function and Dynamics 

Bare Ground + + + 

Groundwater Dynamics Groundwater Quantity § § § § 

Hydrology Surface Water Dynamics ◊ ◊ ◊ 

Surface Water Dynamics 

Persistence of Springs § § 

Water Chemistry Surface Water Quality § § § 

Water 

Water Quality 

Aquatic Invertebrates Aquatic Invertebrates ● § § 
Table 3.2.3. Chihuahuan Desert Network core vital signs, presented by park and funding category within the context of the NPS 

Framework, cont. 

65 

Parks where implemented/

LEVEL 1 LEVEL 2 LEVEL 3 CHDN vital sign 

AMIS BIBE CAVE FODA 

 Invasive Species Invasive/Exotic Plants Invasive/Non-native Plants § § § § 

Desert, Grassland and Shrubland Communities 

Plant Community Composition § § § 

Birds Bird Communities § § § § 

Biological Integrity Focal Species or 

Communities 

Mammals Heteromyid Rodent Communities ● ● 

Landscapes Land Cover + + + + (Ecosystem Pattern and Processes) 

Landscape Dynamics Land Cover and Land Use

Land-use Changes + + + + 

◊ Vital signs being monitored by a network park, another NPS program, or another federal or state agency, using other funding. The network will collabora

efforts. § Vital signs for which the network will implement monitoring protocols in concert with other networks, using funding from the vital signs or water quality m

+ Vital signs for which the network will develop protocols and implement monitoring using funding from the vital signs or water quality monitoring program

● Vital signs that cannot currently be implemented because of limited staff and funding. 
66 

3.3 Justification for Vital Signs 

This section describes the significance and relevance of each core vital sign in evaluating the condition of 

CHDN park ecosystems. Vital signs are presented in the same order as they appear in Table 3.2.3, by 

Level I—Categories of the NPS Ecological Monitoring Framework. 

3.3.1 Air and climate 

Diminishing air quality is a concern in a number of national parks (NPS-ARD 2002), and can 

significantly affect visitor experience. Although most CHDN parks are located some distance from urban 

centers in Texas and Mexico, significant oil and gas development near several network parks in 

southeastern New Mexico and West Texas, and coal-fired power plants in Central Texas, will likely 

increase pollution by nitrates and sulfates. CHDN parks affected by pollution from these cities and energy 

development projects (whether nearby or distant) experience poor air quality due to ozone, nitrogen 

oxides, sulfur dioxide, volatile organic compounds, particulate matter, and toxins. Influenced by weather 

patterns, atmospheric pollutants are carried by the wind, broken down by high temperatures and radiation, 

and then deposited as wet and dry particles in the air, water, soil, vegetation, and on wildlife and humans. 

Atmospheric deposition of nitrogen and sulfur compounds can alter soil processes (e.g., soil nutrient 

cycling), affect plant species composition, directly injure vegetation, affect stability of biological systems, 

and impair water quality (Fenn et al. 2003). Air pollutants that decrease visibility also can affect human 

health, impair viewsheds, and degrade the aesthetic appeal of a national park (Malm 1999). Consequently, 

protection of air quality has become a priority in national parks, and a core vital sign for monitoring in 

many networks (Maniero 2001). 

Under the Clean Air Act of 1970 (as amended in 1977 and 1990), protection of air quality is required in 

all U.S. national parks greater than 5,000 ac (labeled as Class I areas). The Clean Air Act gives nonattainment Class I areas the greatest protection against further deterioration and requires monitoring to 

confirm that air quality and visibility improve or, at minimum, do not further degrade. In addition, 

according to each NPS park’s GPRA mandate, land managers in Class I parks are required to provide 

recommendations on how to protect air, natural, and cultural resources in the park. To evaluate these 

hazards to ecosystem and human health, it is important to monitor air quality conditions and their 

interactions with the physical and biological components of ecosystems. Additionally, monitoring these 

vital signs will provide information for assessing temporal trends in air quality of individual Class I 

CHDN parks and generalized trends for broader regions (NPS-ARD 2002). 

Climate is a primary factor controlling the structure and function of CHDN ecosystems. Measurements of 

temperature, precipitation, wind, humidity, and soil moisture can indicate changing climatic conditions 

and patterns. Key to understanding ecosystem dynamics is an understanding of the roles of climate 

variability, hydrologic interactions with soils, and adaptive strategies of biota to capitalize on spatially 

and temporally variable moisture dynamics (Noy-Meir 1973, Rodriguez-Iturbe 2000, Reynolds et al. 

2004). This information is highly relevant to the interpretation of other vital signs and provides a basis for 

understanding the response of desert ecosystems to future climate variation (Hereford et al. 2004). 

3.3.2 Geology and soils 

White Sands National Monument was established in 1933, to preserve the largest gypsum dune field 

known globally. The park encompasses about half the entire dune field. An understanding of the 

dynamics of the dunes lies at the core mission of the park. Dune dynamics are taken here to include a 

broad spectrum of dune and dune-field aspects: dune formation/destruction, surface processes, migration 

rate, characteristic behavior, dune-dune interactions, and dune-substrate interactions. This vital sign, 

along with groundwater quantity, are the two priority vital signs for WHSA (Kocurek 2008). 
67 

Management and restoration activities in riparian and aquatic ecosystems of the lower Rio Grande in 

BIBE, RIGR, and AMIS are hindered by a vague understanding of the magnitude of changes in channel 

morphology. Flow depletions in the northern branch of the Rio Grande in the United States and in 

Mexico’s Rio Conchos have caused significant reduction in channel-forming discharges in the Rio 

Grande in BIBE. These hydrologic changes have resulted in channel aggradation; channel narrowing and 

development of inset floodplains; reduction in aquatic habitats, especially for native fish and freshwater 

mollusks; increase in invasive/non-native riparian vegetation; and reduction in the quality of recreational 

boating (Schmidt et al. 2003). 

In deserts, geology and soils provide the template upon which biota build integrated ecological systems. 

The availability of water is crucial, and small variations can drastically alter plant and animal 

communities. Both physical and chemical geologic attributes, such as soil texture that influences moisture 

infiltration rates and bulk density, control water availability. Soil type, in conjunction with plant 

communities and their dynamics, topography, and climate regimes, are primarily responsible for broadscale differences in soil moisture across the landscape. Plant-available soil moisture is a key factor in 

understanding ecosystem maintenance in desert ecosystems. 

Biological soil crusts are concentrated in the top 1–4 mm of the soil and comprise over 70% of the living 

ground cover. The main components of soil crusts are cyanobacteria, bryophytes, and lichens, which 

cover most soil spaces not occupied by green plants and are critical in reducing erosion, increasing water 

retention, and increasing soil fertility (Belnap 2001). Because plant cover is sparse in deserts, crusts are 

an important source of organic matter for desert soils. Initial studies in the Chihuahuan Desert indicate 

that crusts require decades for recovery, and these recovery rates are dependent on climatic history, 

particularly variability in precipitation, severity of disturbance, and soil texture. 

Disturbance of the soil surface is a natural process (e.g., animal burrowing, flooding) that can be 

aggravated by anthropogenic activities (e.g., grazing, off-highway vehicle use, mining), leading to largescale disturbance. Soil-surface disturbance causes dust generation, erosion, surface runoff, increased bare 

ground, decreased soil organic matter, increased invasive plant species cover, and vegetation community 

change, all of which may alter plant and animal communities and pose a significant threat to ecosystem 

integrity. Loss of topsoil changes the capacity of soil to function and restricts its ability to sustain future 

uses. Erosion removes or redistributes topsoil, the layer of soil with the greatest amount of organic matter, 

biological activity, and nutrients (Belnap 2003). Erosion breaks down soil structure by exposing organic 

matter within aggregates, which accelerates decomposition and loss. Degraded soil structure reduces the 

rate of water infiltration and increases runoff, which can lead to further erosion. The materials deposited 

by erosion can bury plants; cover roads and trails; accumulate in streams, rivers, and reservoirs; degrade 

water and air quality; and damage or degrade cultural landscapes. 

Herrick and others (1996) developed a suite of indicators for monitoring the health of arid and semi-arid 

ecosystems. These indicators (1) reflected the status of a critical ecosystem process or an economic/social 

value, (2) were unambiguous (i.e., the trajectory of the measure is unidirectional in response to ecosystem 

stressors of increasing intensity), (3) were applicable to the range of ecosystems encountered in arid and 

semi-arid landscapes, and (4) were readily and inexpensively measured. Similarly, Whitford (2002) 

described several indicators that were useful in monitoring programs specific to Chihuahuan Desert 

rangelands, including average size of bare patches, cover of long-lived grasses, a palatability index, and a 

soil surface stability index. Other indicators that may prove useful for assessing rangeland health include 

cover of invasive species and cover of increaser species (native plant species that rapidly spread into 

stressed environments). 
68 

3.3.3 Water 

Groundwater is the source of most springs in the parks, creating habitat for diverse aquatic, riparian, and 

terrestrial biota. Consequently, understanding and monitoring groundwater dynamics has been identified 

as a top priority for network parks. Determining the status and long-term trends in, and developing a 

better understanding of water table levels, groundwater flow paths, and the connection between 

groundwater and surface water resources, are required for predicting the effects of natural and humaninduced hydrological changes (e.g., municipal groundwater withdrawal) and the fate of contaminants 

(e.g., landfill leachate). Precipitation events slowly recharge desert basin aquifers, and this recharge feeds 

scattered springs and wetland habitats. Removing only a small fraction of groundwater from these basins 

can lower the water table and potentially dry up critical surface water resources. Land subsidence can 

disrupt surface drainage, reduce aquifer storage, cause earth fissures, and damage wells and other 

infrastructure (Bawden et al. 2003). Groundwater withdrawal is considered a significant ecosystem 

stressor within the CHDN. 

Surface water resources in CHDN parks (e.g., springs, seeps, streams, rivers, reservoirs) are sparsely 

distributed on the landscape, but critical to the persistence of native biota and many endemic species. 

Surface water dynamics and water chemistry have strong effects on aquatic biota; therefore, biological 

assemblages (e.g., aquatic macro- and microinvertebrates) are often excellent indictors of flow regime, 

water chemistry, and disturbance history. Alteration of surface water resources within desert ecosystems 

has profound ecological and management implications, including loss of species diversity, extinction or 

extirpation of special-status and endemic species, alteration in the composition and distribution of plant 

and animal communities, alteration of culturally significant sites, and inability of parks to meet legal and 

policy mandates. Therefore, CHDN resource managers are very concerned about degradation of surface 

water resources. 

Because CHDN surface waters frequently derive their flow from regional groundwater systems, a primary 

cause of degradation is groundwater withdrawal and diversion. Based on recent drought conditions and 

predictions of weather and water use, future pressures on groundwater resources are expected to increase, 

posing significant threats to surface water availability in network parks. Finally, atmospheric deposition 

of pollution and nutrients carried from agricultural and urban development areas may contaminate park 

surface waters. These chemical and hydrologic changes can cause fundamental shifts in the chemical 

properties of park waters that lead to subsequent shifts in the biotic communities that depend on these 

waters for survival. 

3.3.4 Biological integrity 

The structure and composition of vegetation communities strongly define ecological communities and 

significantly affect ecosystem processes. Invasive plants pose one of the greatest threats to natural and 

cultural resources of the national parks. Non-native plant species are invading new areas and establishing 

at unprecedented rates because global trade and transportation have allowed them to cross 

biogeographical barriers. Potential ecological damage from exotic invasive species includes alteration of 

natural disturbance regimes and ecosystem processes and subsequent effects on native flora and fauna. 

Specific concerns include sustainability of threatened and endangered species; alteration of the density, 

biomass, and diversity of native plant communities; species extirpation/extinction due to changes in fire 

regime; and alteration of basic soil processes. Numerous non-native plant species have been identified in 

CHDN park units.

The desert ecosystems found within the seven CHDN park units host a rich, diverse collection of plant 

communities and landforms. Vegetation and soil constitute the very foundation by which all ecosystem 

functions are intricately connected and upon which they are dependent. Changes in vegetation 

composition and structure can have profound effects on nutrient cycling and soil properties. Climate 

models predict a warmer, drier future for the southwestern United States (Seager et al. 2007). Parks also 
69 

are faced with the unknown effects of air pollution, habitat loss, and altered disturbance regimes (e.g., 

fire, energy development). These factors likely will have significant impacts on CHDN upland plant 

communities. 

The opportunity to see wildlife attracts many visitors to CHDN parks. The geographic location and 

arid/semi-arid environment of these parks provide suitable habitat for a variety of desert, woodland, and 

montane species of the southwestern United States. In particular, desert riparian and grassland 

communities provide important habitats for migrating and wintering birds in the Southwest, despite a 

reduction in quality and quantity during the past 100 years (Ffolliott et al. 2004, Merola-Zwartjes 2005, 

Skagen et al. 2005). The relatively less-disturbed systems in CHDN parks provide refugia for avian 

species seeking these habitats and enhance regional biodiversity. For certain birds, properties of faunal 

assemblages and populations are important indicators of environmental change because they serve a great 

diversity of ecological functions that affect ecosystem productivity, resilience, and sustainability (Marcot 

1996, Bryce et al. 2002, Sullivan et al. 2007). Similar conservation issues affect landbirds in the 

southwestern U.S. and northwest Mexico, making bird monitoring an important international issue, as 

well (Rich et al. 2004). 

Birds are also desirable subjects for long-term ecological monitoring because they have widespread 

public appeal, and changes in park fauna are likely to garner a high level of public interest and generate 

support for corrective or remedial management actions. CHDN parks are well-positioned to contribute to 

regional and national bird monitoring initiatives (e.g., with the adjacent Sonoran Desert, Southern 

Colorado Plateau, and Southern Plains I&M networks; Partners in Flight; Rocky Mountain Bird 

Observatory, parks in adjacent Chihuahua and Coahuila, Mexico) that will provide insight into changes of 

this important focal resource. 

Rodents of the family Heteromyidae are species of significance to Chihuahuan Desert ecosystems. 

Banner-tailed kangaroo rats (Dipodomys spectabilis) are frequently associated with, and are indicators of, 

vegetative condition in Chihuahuan Desert grasslands, whereas other species of Dipodomys often are 

associated with grassland-shrubland transitions (Whitford et al. 1978). Heteromyid rodents can create 

feedbacks in desert systems through burrowing, herbivory, and granivory, all activities that redistribute 

limited resources or change the course of plant community development (Brown and Heske 1990, Guo et 

al. 1995, Whitford and Bestelmeyer 2006). In addition, small mammals play a key role in ecosystem and 

biotic community function as trophic bases for secondary and tertiary consumers. Research suggests that 

environmental variables (including seasonal extremes in temperature, annual energy, moisture, and 

elevation) may predict up to 88% of the variation in mammalian species density for all of North America 

(Badgley and Fox 2000). 

3.3.5 Landscape dynamics 

Landscape-level processes, such as habitat patch mosaic structure, may strongly influence local flora and 

fauna populations. The character of a landscape’s pattern (patch size and structure, distribution, 

connectivity) directly influences the distribution, abundance, and movement of animals (e.g., bighorn 

sheep), and the distribution, abundance, germination, and dispersal of plants. In deserts where many 

organisms are living at or near the threshold for surviving climatic extremes, the availability of resources 

in patches and ability to move among patches are critical factors (Whitford 2002). Fragmentation, 

grazing, and changes in climate and fire regime have had the greatest past and current impacts on 

landscape pattern in CHDN parks. 

Desert habitats (grasslands, shrublands, Tamaulipan thornscrub, and playas) comprise over 75% of 

CHDN land cover. Land cover in GUMO and CAVE, however, is dominated by woodland and forest. 

Land cover is affected by natural events, including climate variation, flooding, vegetation succession, and 

fire, all of which are susceptible to changes in frequency or magnitude due to human activities. Today, 
70 

human-induced change in land cover is a primary factor in habitat loss, the most significant contributor to 

the listing of threatened plant and animal species. Monitoring changes in land cover provides critical 

insights into current or future changes in ecosystem processes (e.g., geomorphic, hydrologic, soil, 

biological) and services (e.g., habitat, stabilizing soils). 

Local and regional land-use practices can dramatically affect soil quality, water quality and quantity, air 

pollution, habitat fragmentation, habitat loss, and contribute to the introduction and spread of invasive 

species. Monitoring changes in land use lends interpretive power to other vital signs and may contribute 

to early detection and management of future resource issues. 

3.4 Links of Vital Signs to Conceptual Models 

Use of the conceptual models, coupled with the workshop participants’ high level of experience with 

environmental indicators for the Chihuahuan Desert, led to selection of vital signs with strong linkages to 

the key issues and resources discussed in Chapter 2 (see Table 3.4). 
71 

Table 3.4. Linkage of vital signs to valued resources and key issues (physical drivers and stressors) from conceptmodels. Vital signs are identified as being a direct measure (DM) or having a strong response (sr) to the issue or r

Resources/Key issues 

National I&M Framework Level 1 

CHDN vital sign 

Climate change 

Air pollution 

Upland watershed 

condition 

Altered disturbance 

regimes 

Geomorphic 

conditions 

Altered hydrologic 

budget 

Geology and 

landforms 

Hydrology 

Recreation and 

local land use 

Invasive species 

Groundwater 

withdrawal 

Adjacent land use 

Watershed 

degradation 

Historic land use 

(grazing) 

Historic land use 

(fire suppression) 

Water pollution 

Air and Climate 

Ozone DM Wet and Dry Deposition DM Visibility and Particulate Matter DM Basic Meteorology DM 

Geology and Soils 

Dune Formation and Stability sr sr sr sr sr sr sr sr Dune Morphology sr sr sr sr River Channel Characteristics sr sr DM sr sr sr Soil Hydrologic Function sr sr sr sr Biological Soil Crusts sr sr Soil Erosion (Wind and Water) sr sr sr sr sr sr sr sr sr 

Water 

Groundwater Quantity sr sr sr sr DM sr sr Surface Water Dynamics DM sr sr sr DM sr DM sr sr sr Persistence of Springs sr sr sr sr sr sr sr sr sr Surface Water Quality DM sr sr sr sr DM Aquatic Invertebrates sr sr sr sr sr sr sr sr DM 
Table 3.4. Linkage of vital signs to valued resources and key issues (physical drivers and stressors) from conceptual ecosyste

72 

Resources/Key issues 

National I&M Framework Level 1 

CHDN vital sign 

Climate change 

Air pollution 

Upland watershed 

condition 

Altered disturbance 

regimes 

Geomorphic 

conditions 

Altered hydrologic 

budget 

Geology and 

landforms 

Hydrology 

Recreation and 

local land use 

Invasive species 

Groundwater 

withdrawal 

Adjacent land use 

Watershed 

degradation 

Historic land use 

(grazing) 

Historic land use 

(fire suppression) 

Water pollution 

Biological Integrity 

Invasive/Non-native Plants sr sr sr sr DM sr sr sr sr Plant Community Composition sr sr sr sr sr sr sr Bird Communities sr sr sr sr sr sr sr sr sr Heteromyid Rodent Communities sr sr sr 

Landscape (Ecosystem Pattern and Processes) 

Land Cover sr sr DM sr sr Land Use DM 
73 

Chapter 4: Sample Design 

4.1 Introduction 

Monitoring goals and objectives are linked to data collection through sampling designs. A quality 

sampling design is necessary to achieve intended monitoring goals and produce rigorous, robust, and 

defensible conclusions. To achieve the greatest precision, accuracy, and resolution, the design must 

carefully consider the physical, chemical, and biological characteristics of each vital sign, and the patterns 

of variability in space and time associated with that vital sign (Oakley et al. 2003). Development of 

sampling designs is often an iterative process that results in adjusting monitoring/sampling objectives to 

accommodate the practical constraints of cost, time, logistics, safety, available information, and 

technology (Elzinga et al. 1998). 

Providing information on the status and trends of selected vital signs is the overarching goal of the 

Chihuahuan Desert Network Inventory and Monitoring program. Status refers to the condition of a vital 

sign at a given point in time, and trend is a directional change in status over time (MacCluskie and Oakley 

2005). Status and trend estimates inform management of resource change, and aid in determining 

potential remediation actions. A sampling design is used for both forms of monitoring to describe the 

process for selecting the population to monitor, the monitoring locations, and the number of locations. 

The strategy for allocating sampling or census efforts through time and space within and among park 

units also is a key component of a sampling design. This chapter provides an overview of sampling 

concepts used to develop CHDN sampling designs and describes the designs CHDN will use to monitor 

each vital sign. 

4.2 Sampling Design Concepts and Definitions 

4.2.1 Overview of sampling designs 

Sampling designs should be concise and understandable. Overly complex designs can be confusing and 

may reduce accessibility of results to the monitoring program audience, many of whom are not well 

versed in statistics and sampling design theory. The CHDN program will be designed as simply as 

possible, with complexity added only as needed to achieve objectives. Of course, when monitoring 

ecosystem structure, function, and processes, some level of complexity cannot be avoided, particularly 

when dealing with large, remote, and difficult-to-access landscapes (McDonald and Geissler 2004). 

After defining clear and concise objectives for each monitoring protocol, the next step in developing a 

sampling design is to define the collection of animals, plants, natural resources, or environmental 

attributes of interest within a specified study. A population consists of elements, the objects on which a 

measurement is taken (Scheaffer et al. 1990). The actual elements sampled are referred to as the sampling 

unit; they are non-overlapping collections of elements (in most cases, the sampling unit is the same as the 

element). A target population is defined as the complete collection of sampling units upon which 

inference is made. Note that this is a statistical population and may or may not refer to a biological 

population. Without a clear idea of the target population, the remaining decisions concerning sampling 

design development are impossible to make. 

We try to quantify our target population by using a sampling frame, defined as the collection of 

sampling units. Common examples of sampling units in the CHDN monitoring program include plots and 

polygons on a digital map, or discrete phenomena, such as lakes, springs, or stream segments. The 

sampling frame could be a list of elements (e.g., springs) or a map of discrete areal elements (e.g., vector-
74 

based GIS coverage of a park). A sample is a subset of sampling units of a population (sampled 

population) that are measured. 

Area and linear frames use geographic boundaries to delineate the target population. Typically, a map of 

the target population serves as the basis for drawing samples. An area frame typically designates the 

population as polygons. A linear frame designates the population as a linear feature, such as a line. 

Linear frames are typically used to represent stream and even riparian systems. The CHDN uses 

probability sampling (described below) to select locations from area and linear sampling frames. 

A list-based frame is a list of possible sample units derived from inventories or intimate knowledge of 

the extent of a resource. A list of all known springs and seeps within a park is an example of this type of 

frame. Samples from a list-based frame can be selected in various ways. A census (described below) can 

be conducted by selecting all samples in a list. Probability sampling can be employed to select samples, 

providing the ability to make inference to all units in the list. When monitoring resources are limited, the 

list can be the basis for the selection of index sites in which either the most representative or the most 

accessible samples are selected for monitoring. 

Potential sources of non-sampling error are another consideration in sampling-design development. Nonsampling error may affect the precision and accuracy of estimates from sampling efforts (Lessler and 

Kalsbeek 1992). Frame error is the error resulting from the disparity between the target population and 

sampled population. Frame error, similar to sampling error, is reduced by increasing the number of units 

in the sampled population (i.e., increasing the sample size). Over-coverage occurs when the sampled 

population contains elements not included in the target population. Under-coverage occurs when elements 

of the target population are omitted from the sampled population. Non-response error results from the 

failure to obtain responses (i.e., measurements) for the entire chosen sample. When missing outcomes are 

very different from the outcomes obtained, the estimates calculated from the responding portion of the 

sample are biased. Measurement error is defined as the difference in measurements obtained and the 

true value of the measure and may include detection errors from observers and instrument errors. The 

three components of non-sampling error (frame, non-response, and measurement), may not always be 

avoidable, but survey planning and design that accounts for these error sources may be helpful in 

reducing the effects of non-sampling error on target population estimates. 

After the target population has been defined, decisions about where and how to distribute sampling 

locations can be made. The CHDN monitoring plan uses three approaches to define the spatial extent of 

monitoring and inference and to determine locations for acquiring observations of vital signs. These 

approaches include probabilistic survey design, index sites, and census. 

A probabilistic survey design requires the delineation of a finite target population and uses probability 

sampling to select sampling units at random from the population (Cochran 1977). These designs have 

fewer assumptions and provide more reliable and legally defensible parameter estimates than other 

approaches, such as those designed to sample from infinite populations (Schreuder et al. 2004, Edwards 

1998, Neusser et al. 1998). The target population is represented by a finite number of non-overlapping 

elements. These non-overlapping elements comprise the sampling frame, and this frame is used in the 

selection of sampling locations and as the basis for making inference from samples to the population 

(Schreuder et al. 2004). Probability sampling is central to survey designs, where each element in the 

sampling frame has a known probability of being included in a sample (i.e., selection probability). This 

selection probability determines the weight of each sample when making inference to the target 

population. The selection probability can be uniform or vary among groups of elements (i.e., unequal 

probability sampling). Additionally, selection probabilities can vary in subsequent additions of sampling 

sites. Proper estimation of population parameters requires maintaining a record of the selection 
75 

probability for each element in each sample-site selection event. Because CHDN parks are typically large, 

probabilistic survey designs will be employed for most vital signs. 

The CHDN employs spatially balanced probability sampling with and without stratification to allocate 

sample units in designs that involve sampling (i.e., that do not use index sites or a census). The network 

relies on the Generalized Random Tessellation Stratified (GRTS; Stevens and Olsen 2004) scheme for 

probability sampling. GRTS is designed to produce a spatially balanced random sample (Stevens and 

Olsen 2004). This method is based on creating a function that maps two-dimensional space into onedimensional space and uses a restricted randomization algorithm to select spatially balanced, random 

samples. Spatially balanced means that sample units are spread out approximately uniformly. Inherent in 

the GRTS scheme is the use of probability sampling and the assignment of selected sampling units to 

panels, such that each panel is spatially balanced. A panel is a collection of sample units visited in the 

same monitoring event (i.e., year). Multiple panels are often used to spread out sampling units over time. 

GRTS samples can be selected using area or linear sampling frames and list-based frames. With list-based 

frames, the term finite GRTS sample is used to indicate that the GRTS process only selects from the listed 

sample units. With area and linear frames, GRTS procedures involve an internal conversion of the frame 

to contiguous minimum mapping units and the selection of sample units from the population of units. 

With stratification, the sampling frame is divided into mutually exclusive strata, and samples are drawn 

for each stratum. Stratification affords greater information about subpopulations (Lohr 1999) and 

increased precision when samples from within strata are more homogeneous than between strata (Cochran 

1977). Sampling locations within strata can be selected in any manner, such as probability sampling with 

GRTS. The CHDN is considering the use of stratification in the monitoring of soil and vegetation vital 

signs (Integrated Uplands monitoring protocol). In the Upland protocol, the strata will be based on 

vegetation types. For other vital sign monitoring efforts, target populations are not stratified. 

Index sites are sample units whose locations are based on judgment; they are usually picked to be 

“representative” sites. Costs, accessibility, and reliance on existing external programs that do not use 

probability sampling for site selection motivate the use of index sites for certain vital signs. A key 

limitation of index sites is that they are not selected using probability sampling; thus, inference beyond 

the actual monitored sites is subject to selection bias. This bias can be mitigated if the relationship 

between sampled and unsampled units is reasonably modeled (e.g., known environmental associations), 

or bias may be minimal if a large portion of the finite population is actually used. 

A census involves the complete enumeration of a vital sign at all possible sample units. However, the 

target population must still be defined to bound the limits of a census. Different strategies can be used in 

the temporal allocation of census efforts within and among park units. 

After the target population, sampling frame, and a strategy for drawing samples are determined, the 

temporal aspect of sampling must be considered. Specifics concerning the sampling occasion, time of 

year (season or month), and time of day depend on the particular aspect of the vital sign being measured. 

However, for larger parks, it may not be feasible to visit the entire sample within a given sampling 

occasion, due to travel time and other factors. Thus, most sample designs proposed for the CHDN will 

rotate field sampling efforts through various sets of sample units over time. In this situation, it is useful to 

define a panel of sample units to a group that is always sampled during the same sampling occasion or 

time period (Urquhart and Kincaid 1999, McDonald 2003). Sample units in the sample population 

become members of a panel through the membership design (McDonald 2003). The allocation procedure 

could be a probabilistic sample, a judgmental sample, or a census. 

The temporal scheduling of sampling, particularly when multiple panels are being used, requires a revisit 

design (Urquhart and Kincaid 1999, McDonald 2003). The revisit design indicates the time of the initial 

visit and the frequency of subsequent visits to sample units of a panel. Sample effort can be rotated 
76 

among panels through time, which also effectively rotates sampling through space. Temporal visitation 

schemes are used for two main reasons. First, the number of plots necessary to achieve the desired 

precision of status and trend estimates may exceed what can be realistically monitored annually. 

Distributing samples through time can achieve the desired precision, but it takes longer to achieve this 

precision than with annual sampling. The second reason pertains to plot fatigue. Annual visitation can 

lead to inadvertent cumulative impacts to a site, such as those resulting from trampling of vegetation and 

soils. A revisit scheme minimizes cumulative and severe impacts. Strict procedures to minimize site 

disturbance during sampling events, however, can allow for annual visitation without deleterious effects. 

Response design (measurements taken at sampling locations) and sample size (the number of samples 

required to meet stated monitoring objectives) are two essential components of any sampling design. 

Response design and sample size components are developed after basic decisions regarding target and 

sampling population, spatial allocation and membership, and revisit strategies have been made. In 

addition, a response design is usually necessary before sample size can be estimated appropriately. This is 

particularly true when response decisions, such as plot shape and size, strongly influence the variability of 

population estimates. However, we must decide about sample size in order to finalize decisions about 

membership and revisit design and, in practice, sampling designs arise out of an iterative process in which 

the order of operations is not rigid. As with the design decisions described above, sample size is primarily 

an exercise in cost-benefit trade-offs, and must be determined through careful consideration of program 

objectives. 

4.2.2 Sample size considerations and magnitude of change 

Populations in the real world are dynamic, and change over time is expected. What is important is 

whether or not there has been meaningful change (meaningful to the ecosystem, public, or park manager), 

what has caused the observed change, and whether further change in the resource is expected. 

To understand what constitutes meaningful, significant change, we must differentiate between statistical 

significance and biological significance. Statistical significance relies on probability and is influenced by 

sample size. Even minor changes (from a biological perspective) will be statistically significant if the 

sample size is large enough. Regardless of statistical significance, we would consider something 

biologically significant if it facilitates a major shift in ecosystem structure or function (e.g., loss of one or 

more species, addition of non-native species, changes in ecosystem processes). 

Thus, from a monitoring standpoint, we are concerned with both statistical and biological significance. 

We want to know whether we are likely to detect a statistically significant change that we also consider 

biologically meaningful. To answer this, we need to decide what level of statistical significance we want 

to attain (i.e., our Type I error rate, or α, discussed below), what level of change we consider biologically 

meaningful and that we hope to detect (i.e., the “effect size”), the amount of variation among sampling 

units, and the number of sampling units. 

In addition to our monitoring objectives, we need to define our sampling objectives. Sampling objectives 

establish a desired level of statistical power (1-β) to detect a specified minimum detectable change or 

effect size and acceptable levels of false-change (α or the probability of a Type I error; Elzinga et al. 

2001). In other words, the timeframe for detecting the desired minimum change given the levels of 

acceptable error and the variance of vital sign measures determines sample-size requirements. All things 

being equal, more samples will allow detection of change sooner, but by extending the reference time for 

change detection, fewer samples per sampling event are required. The number of samples collected is a 

function of each of these components, and decreasing sample size, which can be desirable for cost 

effectiveness, will often force acceptance of higher error and lower power. These tradeoffs are mitigated 

by reducing variance estimates, either through modifications in response design, another component of 

the sampling design (e.g., revisit design), or by accepting a higher minimum effect size (Steidl et al. 
77 

1997). In general, sample size should be large enough to give a high probability of detecting any changes 

that are of management, conservation, or biological importance, but not unnecessarily large (Manly 

2001). Scientists traditionally seek to reduce Type I errors, and accordingly prefer small α levels. In a 

monitoring program such as ours, with a strong resource-conservation mandate, however, it is preferable 

to employ an early warning philosophy by tolerating a higher α but subsequently increasing the power to 

detect differences or trends (Sokal and Rohlf 1995, Roback and Askins 2005). 

Estimates of status and trends from monitoring information are derived in two ways. Direct estimation

uses recorded observations weighted by the selection probabilities of samples and assumes that the 

measured vital sign is fully detectable. Where the probability of detecting an individual or species within 

a sampling unit when it is present is less than 100%, modeled estimates are required. Failing to properly 

account for individual or species detectability leads to a biased value of a vital sign at a sample unit and, 

thus, biased estimates of status and trend (Thompson 2002). In particular, temporal changes in detection 

rates can confound the ability to detect a true change. Incomplete detectability occurs due to perception 

and availability bias (Marsh and Sinclair 1989, Pollock et al. 2004). Perception bias arises from missing 

an individual or species that is available for detection (i.e., non-zero detection probability). For instance, 

an observer is more likely to detect a bird 10 m away than a bird 100 m away. Methods such as capturerecapture (Pollock 2000) and distance sampling (Buckland et al. 2001, 2004) account for this component 

of individual detectability (see also Williams et al. 2002). Availability bias results when individuals or 

species are present but unavailable for detection (e.g., Pollock et al. 2004). For instance, if a plant species 

is unrecorded during a sampling occasion because it was dormant underground, availability bias results. 

The CHDN uses model-based estimates, where possible, to properly account for incomplete detectability. 

4.3 Sampling Design by Vital Sign 

CHDN sampling designs can be organized by the underlying sampling frame (area or linear-based, and 

list-based) or the use of index sites or a census. Table 4.3 lists the protocols planned for development, the 

vital signs they address, and the proposed sampling design for each protocol. For each protocol, the table 

identifies the sample design type, target population, sample frame, and proposed revisit design. 

The CHDN monitoring program emphasizes, where possible, co-location of vital-sign monitoring 

locations and co-visitation. Co-location refers to monitoring multiple vital signs at the same physical 

locations. Co-visitation refers to recording observations on multiple vital signs during a sampling 

occasion. An obvious benefit of both is operational efficiency. Overall time and costs for plot 

establishment and sampling are reduced when multiple vital signs are measured at the same place and 

time. Also, measures of multiple vital signs at the same locations can provide important insights into 

ecological processes with direct application to management. For example, monitoring drivers and 

responses aids in interpreting reasons for observed changes. Co-located vital signs enhance the 

understanding of causes and consequences of interactive behaviors (Michener et al. 2001), and when the 

lack of precision masks statistically significant change, the collective temporal consistency in trends 

among vital signs can serve as a weight of evidence of change. Co-location and co-visitation of vital signs 

minimize confounding factors and enhance assessments of such subtle, but possibly important, trends. 
78 

Table 4.3. Summary of Chihuahuan Desert Network sample design specification by protocol. Protocol Vital sign(s) Sample design type Generalized target population Sample frame Air Quality Ozone, Wet and Dry Deposition, 

Visibility and Particulate Matter 

Index (existing air-quality stations) 

Index sites, although measures are representative of a larger area 

NA 

Climate Basic Meteorology Index (existing weather 

stations) 

Index sites, although measures are representative of a larger area 

NA 

Dune Dynamics Dune Formation and Stability, 

Dune Morphology 

Census Census NA 

River Channel Morphology 

River Channel Characteristics Index Index sites NA 

Groundwater Quantity 

Groundwater Quantity Index Index sites NA Surface Water Dynamics Index Index sites NA 

BIBE: GRTS (finite) BIBE: List-based 

frame 

List-based frame: List of springs and seeps 

Persistence of Springs 

Other parks: Index, census, or GRTS (finite) 

Index sites, census, or park’s list-based frame 

List-based frame: List of known springs and seeps in a park 

Surface Water Quality Index Index sites NA Aquatic Invertebrates (rivers and streams) 

Index Index sites NA 

BIBE: GRTS (finite) BIBE: List-based 

frame 

List-based frame: List of known springs and seeps

Surface Water Quality and Dynamics 

Aquatic Invertebrates (seeps and springs) 

Other parks: Index, census, or GRTS (finite) 

Index, census, or listbased frame List-based frame: List of known springs and seeps 
Table 4.3. Summary of CHDN sample design specification by protocol, cont. 

79 

Protocol Vital sign(s) Sample design type Generalized target population Sample frame Invasive/Nonnative Plants Invasive/Non-native Plants GRTS (finite) Areas along roads, arroyos, and other 

areas predicted as suitable habitat for focal plant species 

Area frame developed using park maps of topos, roads, trails, veg. 

Landbirds Bird Communities (desert 

grassland) 

GRTS (area)/model-based estimates of abundance or occupancy at the sampleunit level, co-located with subset of Integrated Uplands vital signs locations 

Desert grassland ecological sites in desert ecosystems 

Area frame: Map of ecological sites that correspond to desert grasslands in desert ecosystems 

 Bird Communities (riparian) GRTS (area)/model-based 

estimates of abundance or occupancy at the sampleunit level 

Riparian systems in river, desert, foothill, and montane ecosystems 

Area frame: Maps of riparian areas in river, desert, foothill, and montane ecosystems. 

Integrated Uplands (Soils and Vegetation) 

Plant Community Composition, Soil Hydrologic Function, Biological Soil Crusts, Soil Erosion (Wind and Water), Bare Ground 

GRTS (area) (co-location and co-visitation of all vital signs) 

Desert grasslands, and shrublands in desert and foothill ecosystems 

Area frame: Maps of ecological sites that correspond to grasslands, shrublands, woodlands in desert and foothill ecosystems 

Landscape Patterns and Dynamics 

Land Cover, Land-Use Changes Census Census NA 

Protocols follow the order presented in the NPS Ecological Monitoring Framework. 

81 

Chapter 5: Monitoring Protocols 

“Monitoring protocols are detailed study plans that explain how data are to be collected, managed, 

analyzed, and reported and are a key component of quality assurance for natural resource monitoring 

programs. Protocols are necessary to ensure that changes detected by monitoring actually are occurring 

in nature and not simply a result of measurements being taken by different people or in slightly different 

ways. 

. . . A good monitoring protocol will include extensive testing and evaluation of the effectiveness of the 

procedures before they are accepted for long-term monitoring. Peer review of protocols and revisions are 

[sic] essential for their credibility. The documentation should include reviewers’ comments and authors’ 

response.” 

—Oakley and others (2003)

5.1 Protocol Overview 

Currently, the CHDN plans to develop 10 protocols covering 21 vital signs during the first three years of 

the monitoring program. Table 5.1 lists the relevant vital signs for each CHDN protocol and relates their 

association to justifications for monitoring, monitoring objectives, and parks in which each protocol will 

be implemented. For vital signs monitored with I&M funding, one protocol will be new and applied only 

in the CHDN (Dune Dynamics). Other protocols (Integrated Uplands, Landbirds, Invasive Plants, River 

Channel Morphology) will be existing NPS or other approved protocols. The remaining protocols will be 

developed through multi-network (Air Quality, Climate, Groundwater, Surface Water Dynamics) or 

servicewide (Landscape Patterns and Dynamics) efforts. Chapter 9 summarizes our schedule for 

development and implementation of these protocols. The CHDN also will develop supplemental 

documents pertaining to data management, data analysis, and data reporting from existing NPS program 

protocols (e.g., Air Quality). 

There is not a 1:1 relationship between CHDN vital signs and protocols (Table 5.1). Rather, a single 

protocol may cover multiple vital signs, and data relevant to a vital sign may result from more than one 

protocol. This organizational scheme increases both the efficiency and integration of protocol 

development and in-field sampling. For example, when and where crews are collecting landbirds data, 

they could also sample soil and vegetation vital signs (Integrated Uplands protocol). 

5.2 Protocol Development Process 

Monitoring protocols identify methods for gathering data, outline a process to collect data, and establish 

how data will be analyzed and reported. A good monitoring protocol should be appropriate for the task, 

accurate, reliable, feasible, and cost-effective (Margoluis and Salafsky 1998). Protocols contain detailed 

study plans, clear objectives, unambiguous standard operating procedures (SOPs) for data collection and 

management, quality assurance/quality control (QA/QC), analysis, training and equipment requirements, 

documentation of protocol changes, and relevant support information. Careful design and documentation 

of protocols are necessary to ensure that changes detected by monitoring actually are occurring in nature 

and do not stem from measurement variability introduced when different people or methods are used 

(Oakley et al. 2003). Rigorous protocols are essential for effective monitoring of vital signs through time. 
82 

Table 5.1. CHDN protocols with relevant vital signs, parks included, justifications, and monitoring 

objectives. 

Protocol

Vital signs 

Air Quality1 

Ozone 

Wet and Dry Deposition 

Visibility and Particulate Matter 

Parks BIBE, GUMO, CAVE2

Justification The quality of the air and atmospheric conditions can influence the functioning of park 

ecosystems and visitor experience. A number of plant species are negatively impacted by 

excessive ozone and atmospheric pollutants (e.g., nitrates, sulfates) deposited through 

fallout over parks. Continued development of energy sources in southeastern New Mexico 

and West Texas likely will increase pollution. Excessive particulate matter from industrial 

wastes can obscure viewscapes and trigger human respiratory responses, diminishing the 

aesthetic appeal of park visitation. Class I park areas must meet federal air-quality 

standards. Among CHDN units, active monitoring occurs only at two Class I air-quality parks, 

and partial monitoring at a third park. Existing efforts through several regional and national 

networks of climate stations collect these data and provide the NPS national I&M programs a 

portal to access summaries and raw data 

Monitoring 

objectives 

1. Report on the seasonal and long-term trends in concentrations of nitrogen and sulfur 

from wet deposition at BIBE and GUMO. 

2. Report on the seasonal and long-term trends in dry deposition chemistry at BIBE. 

3. Report on the seasonal and long-term trends in ozone concentration at BIBE, CAVE, 

and GUMO. 

4. Report on seasonal and long-term trends in visibility-reducing pollutants at BIBE and 

GUMO. 

5. Determine patterns of year variability and long-term trends in air quality vital signs in 

CHDN parks to detect changes in air quality that correlate with changes in other CHDN 

vital signs. 

Protocol

Vital signs 

Climate1 

Basic Meteorology 

Parks AMIS, BIBE, CAVE, FODA, GUMO, WHSA 

Justification Climate is the most extensive ecological driver in the Chihuahuan Desert. Timing, intensity, 

and duration of precipitation and temperature influence most ecological processes. Change 

in meteorological conditions that define climate may have dramatic influence on system 

processes and species distributions. Shifts in timing and duration in life cycles of certain 

plants may indicate aspects of climate change and provide a link for understanding climatechange effects on other organisms. Existing efforts through several regional and national 

networks of climate stations collect these data and provide the NPS national I&M programs a 

portal to access summaries and raw data. 

Monitoring 

objectives 

1. Report on status and longer-term trends (monthly, seasonal, and annual) of common 

meteorological variables (i.e., temperature, precipitation) at existing monitoring stations 

in and near CHDN parks. 

2. Determine patterns of year variability and long-term trends in common meteorological 

variables in CHDN parks to detect changes in climate that correlate with changes in 

other CHDN vital signs. 

 

 
Table 5.1. CHDN protocols with relevant vital signs, parks included, justifications, and monitoring objectives, 

cont. 

83 

Protocol

Vital signs 

Dune Dynamics 

Dune Formation and Stability 

Dune Morphology 

Parks WHSA, GUMO2

Justification WHSA was established in 1933, to preserve the world’s largest gypsum dune field. The 

monument encompasses about half of the dune-field extent. An understanding of relevant 

dune-field dynamics is vital to the park’s core mission. Dune dynamics are taken here to 

include a broad spectrum of dune and dune-field aspects: dune formation/destruction, 

surface processes, migration rate, characteristic behavior, dune–dune interactions, and 

dune–substrate interactions. This vital sign, along with groundwater quantity, are the top two 

priority vital signs for WHSA. 

Monitoring 

objectives 

1. Determine characteristics of single-dune dynamics on a seasonal and composited 

yearly basis. 

2. Determine long-term trends in dune dynamics at the dune-field scale during 5–10-year 

intervals. 

3. Determine seasonal and composited yearly trends in the sediment budget at the dunefield scale during 5–10-year intervals. 

Protocol

Vital signs 

River Channel Morphology3 

River Channel Characteristics 

Parks AMIS2, BIBE, RIGR2

Justification Changes in channel morphology affect sediment loads and alter riparian habitats. Increased 

channelization contributes to reduction in active floodplains, reducing or eliminating 

recruitment of cottonwoods. Reduction in active sediment movements causes reduction in 

suitable habitat for native fish and freshwater mollusks. Coarse-scale changes in river 

channel characteristics can be measured through aerial imagery. 

Monitoring 

objectives 

Determine long-term trends in channel location and characteristics of the Rio Grande at 

intervals following major bankfull- or out-of-bankfull events. (These are events that cause 

changes in river geomorphology.) 

Protocol

Vital signs 

Groundwater Quantity4 

Groundwater Quantity 

Parks AMIS, BIBE, CAVE, FODA, GUMO, WHSA 

Justification The arid and semi-arid terrestrial ecosystems within the CHDN generally are adapted to 

water-limited environments. The quantity of subsurface water (groundwater) is becoming 

increasingly important for CHDN parks. Groundwater is the major source of potable water for 

human subsistence within and adjacent to CHDN parks, and the discharge component of 

springs and seeps. Dams, irrigation, municipal withdrawals, and instances of groundwater 

depletion have significantly changed the hydrographs of many surface waters in CHDN 

parks, with large-scale effects on aquatic and riparian ecosystems. By summarizing and 

evaluating data from USGS stream gages, groundwater-level monitoring instrumentation at 

some parks, and state-based (regional) monitoring of groundwater levels, CHDN will help to 

identify changes in river flow and detect impending threats to park groundwater sources. 

Sampling for these vital signs will be co-located and co-visited by the same personnel 

monitoring surface water quality vital signs to increase monitoring efficiency and ensure 

standardization of procedures. 

Monitoring 

objectives 

Determine the seasonal and annual status, and longer-term trends in groundwater resources 

(as estimated from existing wells) in or adjacent to all CHDN park units. 
Table 5.1. CHDN protocols with relevant vital signs, parks included, justifications, and monitoring objectives, 

cont. 

84 

Protocol

Vital signs 

Surface Water Quality and Dynamics4 

Surface Water Dynamics 

Persistence of Springs 

Surface Water Quality 

Aquatic Invertebrates 

Parks AMIS, BIBE, CAVE, GUMO 

Justification The arid and semi-arid terrestrial ecosystems within the CHDN are generally adapted to 

water-limited environments. Surface water quality is a monitoring priority for tracking park 

ecological health, measuring compliance with federal and state laws and standards, and 

detecting threats to human health. In the CHDN, the Rio Grande and Amistad International 

Reservoir are the major sources of surface water for humans and aquatic-biological 

communities along the Texas–Mexico border. The quality of water in the Rio Grande is of 

particular concern, given the economic and ecological role it plays in the border region and 

its historical exposure to contaminants. Smaller perennial streams, and scattered springs 

and seeps, provide additional water for support of park biota. Although limited in extent, 

these microcosms can add considerably to the biodiversity of arid and semi-arid landscapes. 

Monitoring water quality vital signs will help to demonstrate whether park water quality is 

being protected or maintained, and indicate whether restoration is required. Sampling for 

these vital signs will be co-located and co-visited by the same personnel to increase 

monitoring efficiency and ensure standardization of procedures. 

Monitoring 

objectives 

Regulatory and Park Critical Objective: 

1. Report on seasonal and annual status and trends for core water quality vital signs 

for Segments 2306 and 2307 of the Rio Grande, impaired water under Section 

303(d) of the Clean Water Act. 

2. Determine seasonal and annual status and trends for core water quality vital signs 

at selected sites in water resources classified as critically important by each park in 

AMIS, BIBE, CAVE, and GUMO. 

Surface Water Quality and Dynamics 

1. Determine the seasonal and annual status and longer-term trends in water quantity 

and core water quality measures for select sites in the Rio Grande in BIBE and 

RIGR, and report on these trends from existing stations. 

2. Determine the seasonal and annual status and longer-term trends in water quality 

and quantity measures at selected sites for perennial streams in BIBE, CAVE, and 

GUMO. 

3. Determine the seasonal and annual status and longer-term trends in measures of 

wetness in select springs in BIBE, CAVE, and GUMO. 

4. Determine the status and longer-term trends in measures of aquatic invertebrate 

communities in selected sites of the rivers, perennial streams in BIBE3

, CAVE, and 

GUMO, and report on these trends from existing stations. 

5. Determine the status and longer-term trends of aquatic invertebrate communities at 

select springs in BIBE3

, CAVE, and GUMO. 

6. Report on status of monthly, seasonal, and annual reservoir levels and long-term 

trends from existing International Boundary Water Commission stations in AMIS. 

 

 

 

 

 

 
Table 5.1. CHDN protocols with relevant vital signs, parks included, justifications, and monitoring objectives, 

cont. 

85 

Protocol

Vital signs 

Invasive/Non-native Plants4

Invasive/Non-native Plants 

Parks All 

Justification Invasion and establishment of non-native plants is one of the most serious threats to 

maintaining ecosystem integrity in CHDN parks. Aggressive species, such as salt cedar, 

giant cane, and Lehmann lovegrass, can rapidly change plant community composition and 

function. If invasive plant species dominate a community, biotic diversity is greatly reduced, 

not only by simplifying the number of plant species, but also by eliminating interactions with 

higher trophic levels. Some invasive plant species can alter driving processes, such as fire 

regimes. Multiple laws and executive orders deal specifically with invasive species. 

Detecting new problem species early before they have a chance to spread, and while they 

are still in small controllable populations, is important to cost-effective resource 

management. 

Monitoring 

objectives 

1. Detect the initial occurrence for any of a subset of high-priority species in areas of high 

invasion probability. 

2. Determine changes in the status and trend (density, abundance or extent) of a subset of 

high-priority species in areas of high invasion probability. 

3. Determine changes in species composition of a subset of high-priority species in areas 

of high invasion probability, taking into account any management treatments that 

occurred between sampling intervals. 

Protocol

Vital signs 

Landbirds4

Bird Communities 

Parks All 

Justification CHDN parks can serve as reference sites for helping interpret ecoregional trends for 

common breeding birds. Riparian bird communities, in particular, are a desired focal 

resource for many park visitors in this network and provide a condition indicator for a rare 

and limited habitat type. Monitoring of bird communities in conjunction with other adjacent 

I&M networks (Sonoran Desert and Southern Plains), as well as regional initiatives, will 

provide insight into changes of this important focal resource at larger regional scales. 

Monitoring 

objectives 

1. Provide occupancy and trend in occupancy estimates for breeding landbirds. 

2. Estimate species richness, composition, and associated parameters of landbird 

community dynamics. 

3. Where feasible, estimate population density and trend estimates for common 

breeding landbirds. 

4. Where feasible, incorporate vegetation monitoring from Integrated Uplands protocol 

to augment landbird sampling and increase efficiency. 

 

 
Table 5.1. CHDN protocols with relevant vital signs, parks included, justifications, and monitoring objectives, 

cont. 

86 

Protocol

Vital signs 

Integrated Uplands (Soils and Vegetation)4

Plant Community Composition 

Soil Hydrologic Function 

Biological Soil Crusts 

Soil Erosion (Wind and Water) 

Bare Ground 

Parks BIBE, CAVE, FODA, GUMO, WHSA 

Justification Soils and plants provide the foundation for most terrestrial and some aquatic communities. 

Condition of these focal resources reflects effects of key ecological drivers and system 

stressors. Soil and plants figure prominently in ecosystem function and biological diversity. 

Incursion of desert-grassland-dominated communities by woody shrubs, and loss of riparian 

plant communities, have predominated through much of the Southwest. Continuation of 

these trends will result in loss of biotic diversity in some parks. Reduction in the numbers of 

these communities also may indicate impacts of climate change. CHDN monitoring will 

target these areas and other areas to co-locate with other vital signs. 

Monitoring 

objectives 

1. Determine the status and long-term trends in soil stability, bare ground, magnitude and 

extent of soil erosion, and soil hydrologic function within selected grassland and 

shrubland communities of the desert and foothill ecosystems. 

2. Determine long-term trends in the composition, structure, and relative abundance of 

dominant and subdominant perennial plant species and biological soil crusts within 

selected grassland and shrubland communities in the desert and foothill ecosystems. 

Protocol

Vital signs 

Landscape Patterns and Dynamics5 

Land Cover 

Land-Use Changes 

Parks AMIS, BIBE, CAVE, FODA, GUMO, WHSA

Justification Changes in landscape patterns beyond park boundaries are often informative about the risk 

of impending impacts. Changes in land use (e.g., road densities, increasing number of oil, 

gas, and wind energy sites) can impact park resources. Changes in landscape can identify 

impending issues, such as future loss and fragmentation in wildlife habitats, isolation of park 

resources, potential for water scarcity and pollution, and invasion of non-native species. 

Trends in land-cover amounts and distribution may provide insight into future changes to 

biotic diversity. These changes will be interpreted along with other temporal and spatial 

patterns observed from ground-level field sampling of vegetation communities and trends in 

climate. 

Monitoring 

objectives 

Determine patterns and long-term trends in spatial and temporal landscape change within 

and adjacent to CHDN parks based on changes in land-use (e.g., road density, building 

density, energy developments sites) and land-cover distribution (vegetation classes). 

Protocols follow the order presented in the NPS Ecological Monitoring Framework. 

1 = These protocols are primarily focused on summarization, analysis, and reporting of data obtained through ongoing monitoring by 

other programs. Opportunities to partner/collaborate with other NPS programs (e.g., Air Resource Division), networks, or other 

agencies will be explored. 

2 = This park will be monitored if resources permit. 

3 = Protocol implementation will complement work already being conducted on the Rio Grande and will be cost-shared with Big 

Bend National Park. CHDN’s role will largely be data management and reporting. 

4 = An existing protocol will be implemented to monitor this vital sign. Data collection and management will be conducted in 

partnership with other networks. 

5 = This protocol will be fully developed following the conclusion of the servicewide I&M program’s effort. The national office has 

taken a lead role in developing standards and useful analytical techniques. 
87 

Where CHDN funding is to be used for monitoring, the network will either (A) make use of protocols 

completed by other I&M networks, other agencies, or programs that already have been peer-reviewed and 

field-tested, or (B) if protocols are developed internally, they will (1) follow the Oakley and others (2003) 

protocol standards, (2) be peer-reviewed, and (3) be approved by the regional I&M program manager 

before they are finalized for long-term monitoring. The CHDN intends to adopt protocols developed by 

the Southern Plains Network for Landbirds and Invasive Plants, and the Sonoran Desert Network for 

Integrated Uplands. Other efficiencies, such as sharing administration of agreements, using common 

databases and data management efforts, and using common analysis and reporting, will also be explored. 

The CHDN is working in concert with these and other networks to develop protocols for Air Quality, 

Climate, Groundwater Quantity, and all vital signs monitoring associated with seeps and springs. For the 

River Channel Characteristics vital sign, the CHDN will manage data collected by BIBE and others using 

peer-reviewed protocols and use that data for reporting. Dune Dynamics is the only vital sign protocol 

that the CHDN will develop internally. 

The standard format for an NPS monitoring protocol (Oakley et al. 2003) consists of three sections: (1) a 

narrative, (2) a set of SOPs, and (3) supplemental or supporting materials. The narrative provides an 

overview of the background and objectives, sampling design, field methods, data handling, analysis and 

reporting, personnel requirements and training, and operational requirements. The SOPs provide detailed 

procedures for all components described in the narrative. For example, additional details may include 

specifics on how to use, maintain, or calibrate a particular piece of equipment. Supplemental materials 

include materials such as databases, GIS layers, related data and reports, and reviewer comments. 

Additionally, regardless of the source of the monitoring protocols (internally developed or adopted and 

modified), during the development period, areas of uncertainty will be addressed through pilot field 

testing of sampling procedures. Following reviews and revision, the approved protocol will be accepted 

for full implementation, and formal monitoring will commence. 

For each protocol, CHDN staff ultimately are responsible for ensuring that the objectives and final 

protocol meet the needs of CHDN parks, are realistic and efficient, and take advantage of opportunities to 

integrate monitoring among multiple protocols (e.g., through co-location of vital signs to be sampled). 

For vital signs already being monitored by existing programs, the CHDN will work to gather and archive 

copies of the existing protocols, SOPs, and QA/QC guidelines. For protocols that already exist or are 

being cooperatively developed by multiple networks, the CHDN will focus its efforts on ensuring that 

appropriate sampling frameworks are designed, and on developing SOPs focused on data access, analysis, 

and reporting on the vital signs. 

The CHDN plans to monitor or report on a maximum of 21 vital signs associated with 10 protocols. 

Monitoring of these vital signs will be guided by the protocols in Table 5.1. Again, when possible, 

existing sources of NPS-approved monitoring protocols will be adopted or modified as necessary. 

Subject-matter experts will be used to modify existing, or develop new, protocols (including sampling 

designs) for monitoring CHDN vital signs, when necessary (Appendix J). Submittal of protocols for peer 

review and approval is expected to occur from the end of 2010 through 2013. The timeframe is dependent 

on the amount of modification or development required for each protocol. 

5.3 Protocol Development Summaries 

A Protocol Development Summary (PDS) is required for each monitoring protocol planned for 

development and implementation by the CHDN monitoring program. The CHDN has written a PDS for 

each of the 10 protocols shown in Table 5.1 (see Appendix J). 

89 

Chapter 6: Data Management 

6.1 Introduction 

The central mission of the NPS I&M program is to acquire, manage, analyze, and distribute scientific 

information on the status and trends of specific park natural resources. Intended users of this information 

include park managers, cooperators, researchers, Congress, policymakers, and the general public. A 

cornerstone of the I&M program is the strong emphasis placed on data management. The Chihuahuan 

Desert Network expects to invest over 33% of its available resources in data management, analysis, and 

reporting activities. Because of the size and complexity of the elements comprising network data 

management, a separate Data Management Plan (DMP) has been developed and is included in this report 

as Appendix K. 

6.2 Data Management Plan 

The goal of the CHDN data management program is to maintain, in perpetuity, the ecological data and 

related analyses that result from the network’s inventory and monitoring work. The CHDN DMP 

describes the resources and processes required to ensure the accuracy, security, longevity, and 

accessibility of data acquired or managed by the CHDN. 

6.2.1 Data accuracy 

The quality of the data collected and managed by the I&M program is paramount. Analyses performed to 

detect ecological trends or patterns require data with minimal error and bias. Inconsistent or poor-quality 

data can limit the detection of subtle changes in ecosystem patterns and processes. This could lead to 

incorrect interpretations and conclusions that may lead to poor management decisions and greatly 

compromise the credibility and success of the I&M program. To ensure that the CHDN produces and 

maintains data of the highest possible quality, procedures are established to identify and minimize errors 

at each stage of the data life cycle. 

6.2.2 Data security 

Digital and hard-copy data must be maintained in environments that protect against loss, either due to 

electronic failure or to poor storage conditions. Digital data of the CHDN are stored in multiple formats 

on a secure server and backed up through an integrated backup routine that includes rotation to off-site 

storage locations. In addition, the CHDN will work with NPS museum curators and archivists to ensure 

that related project materials, such as field notes, data forms, specimens, photographs, and reports, are 

properly cataloged, stored, and managed in archival conditions. 

6.2.3 Data longevity 

Countless data sets have become unusable over time, either because the format is outdated (e.g., 

punchcards), or because metadata are insufficient to determine the data’s collection methods, scope, 

intent, quality assurance procedures, or format. Proper storage conditions, backups, and migration of data 

sets to current platforms and software standards are basic components of data longevity. Comprehensive 

data documentation is another essential component. The CHDN uses a suite of metadata tools to ensure 

that data sets are consistently documented and in formats that conform to current federal standards. 
90 

6.2.4 Data accessibility 

One of the most important responsibilities of the I&M program is to ensure that data collected, developed, 

or assembled by CHDN staff and cooperators are made available for decisionmaking, research, and 

education. Providing well-documented data to park managers in a timely manner is especially important 

to the success of the program. The CHDN must ensure that: 

 Data are easily located and obtained, 

 Data are subjected to full quality control before release, 

 Data are accompanied by complete metadata, and 

 Sensitive data are identified and protected from unauthorized access and distribution. 

The CHDN’s main mechanism for distributing the network’s data will be the Internet, which will allow 

data and information to reach a broad community of users. As part of the NPS I&M program, web-based 

applications and repositories have been developed to store a variety of park natural resource information 

(Table 6.2.4). 

Table 6.2.4. Data to be provided on the CHDN and national I&M web sites. 

Web application name Data available at site 

CHDN web site Reports and metadata for CHDN projects; certified species lists; search and reporting 

tools for data; data downloads; database templates 

(http://science.nature.nps.gov/im/units/chdn/). 

IRMA Integrated Resource Management Application: Entry portal for the applications listed 

below. 

NPSpecies Database of vascular plant and vertebrate species known or suspected to occur on NPS 

park units (http://science.nature.nps.gov/im/apps/npspp/). 

NatureBib Bibliography of park-related natural resource information 

(http://www.nature.nps.gov/nrbib/). 

NPSFocus Portal to a variety of NPS information sources; will include NatureBib and NPS Data 

Store links (http://npsfocus.nps.gov/). 

NPS Data Store Park-related metadata and selected data sets (spatial and non-spatial) 

(http://science.nature.nps.gov/nrdata/). 

The Chihuahuan Desert Network’s information acquires its real value when it reaches those who can 

apply it. If these web portals do not meet a specific user’s requirements, CHDN data management staff 

will work with users on an individual basis to ensure receipt of the desired information in the requested 

format. 

6.3 Data Sources and Priorities 

There are multiple sources of data related to natural resources in CHDN parks. Types of work that may 

generate these data include: 

 Inventories 

 Monitoring 

 Protocol development pilot studies 

 Special-focus studies performed by internal staff, contractors, or cooperators 

 External research projects 
91 

 Studies performed by other agencies on park or adjacent lands 

 Resource impact evaluations related to park planning and compliance 

 Resource management and restoration work 

Because the I&M program focuses on natural resource inventories and long-term monitoring, the data that 

result from these efforts are the CHDN’s first data-management priority. However, the standards, 

procedures, and approaches to data management developed by the CHDN are being applied to other 

natural resource data sources. 

For example, all I&M network parks need a basic suite of resource inventory data to effectively manage 

their resources and support a successful monitoring program. The servicewide I&M program has 

determined that all network parks sould acquire a minimum of 12 inventory data sets, including both 

biotic and abiotic components. The CHDN is working with individual parks and national NPS programs 

to acquire and standardize these basic resource data sets, and make them widely available. These data sets 

are: 

 Natural resource bibliography 

 Base cartographic data 

 Air quality data 

 Air-quality-related values 

 Climate inventory 

 Geology resources inventory 

 Soil resources inventory 

 Water body location and classification 

 Baseline water quality data 

 Vegetation inventory 

 Species lists 

 Species occurrence and distribution 

6.4 Data Management Categories 

Data from park and network sources generally can be placed in the following data management 

categories: 

1. Data managed in servicewide databases. 

2. Data managed in three databases developed by the I&M WASO office. NatureBib is a 

bibliographic tool for cataloging reports, publications, or other documents that relate to natural 

resources in park units. NPSpecies is used by the network to develop and maintain lists of 

vertebrates and vascular plants in network parks, along with associated supporting evidence. 

Dataset Catalog is used to document primarily non-spatial, natural-resource-related databases or 

other data assemblages. As development of the Integration of Resource Management 

Applications project progresses, the CHDN will use this data portal as the primary portal for 

accessing data. 

3. Data developed or acquired directly by the network as a result of inventory, monitoring, or other 

projects, and managed by the CHDN. 

4. Project-related protocols, field data, reports, spatial data, and associated materials, such as field 

forms and photographs provided to the CHDN by the parks or contractors, or developed by 

CHDN staff. 
92 

5. Data that, though not developed or maintained by the CHDN, are used as primary data sources or 

provide context to other data sets. Examples of this category include GIS data developed by 

parks, other agencies, or organizations; national or international taxonomic or other classification 

systems; and climate, air quality, or hydrologic data collected or assembled by regional or 

national entities. 

6. Data that the CHDN assists in managing but is acquired and maintained by network parks. 

Because of the range of data management expertise in network parks, the CHDN provides data 

management assistance for high-priority data sets or those that may benefit from standardized 

procedures. 

The categories listed above can contain one or more of the following data formats: 

 Hard-copy documents (e.g., reports, field notes, survey forms, maps, references, administrative 

documents) 

 Physical objects (e.g., specimens, samples, photographs, slides) 

 Electronic text files (e.g., MS Word files, e-mail, web sites) 

 Electronic tabular data (e.g., databases, spreadsheets, tables, delimited files) 

 Spatial data (e.g., shapefiles, coverages, remote-sensing data) 

 Miscellaneous electronic files (images, sounds, other files with proprietary formats) 

Each of these data formats has specific requirements for ongoing management and maintenance, which 

are addressed in the DMP. 

6.5 Data Management and the Project Life Cycle 

Inventory and monitoring projects are typically divided into five broad stages: planning and approval, 

design and testing, implementation, product integration, and evaluation and closure (Figure 6.5). During 

all stages of data management, staff collaborate closely with project leaders and participants. Specific data 

management procedures correspond to these stages and are fully detailed in the chapters of the DMP. 

Building upon the data management framework presented in Chapters 1–4 of the DMP, Chapter 5 is 

devoted to data acquisition and processing, and Chapter 6 provides a framework for verifying and 

validating data that have been collected and entered into databases. Dataset documentation is the subject 

of Chapter 7, reporting in Chapter 8, and data dissemination, including issues such as data ownership, 

data sensitivity, and compliance with the Freedom of Information Act, are addressed in Chapter 9. 

Chapter 10 provides a framework for the long-term maintenance, storage, and security of CHDN data. For 

monitoring projects, extensive protocol SOPs provide detailed guidance on all stages of a project’s data 

life cycle. These SOPs are specific to each project, yet all fall within the guidelines established in the 

DMP. 
93 

Figure 6.5. Model of data life cycle stages. 
94 

6.6 Water Quality Data 

Water quality data collected as part of the network’s monitoring program have distinct data management 

requirements. This includes using the NPSTORET desktop database application at the network to help 

manage data entry, documentation, and transfer to the NPS Water Resources Division (NPS-WRD). The 

CHDN will ensure the content is transferred at least annually to the NPS-WRD for upload to the 

Environmental Protection Agency’s STORET (STORage and RETrieval) database (Figure 6.6). For the 

other water resources indicators (listed below), the CHDN will report on summarized data sets for which 

the network parks already have established archiving procedures: 

• Groundwater Dynamics 

• Aquatic Invertebrates (macro and micro) 

• Surface Water Hydrology 

The CHDN will obtain a download of all relevant data for a specific water year and transfer the file to the 

Water Resources Division for upload into STORET. 

Figure 6.6. Data flow diagram for water quality data. 

6.7 Data Management Plan Maintenance 

The CHDN will strive to maintain a DMP that is useful to a broad audience and can provide guidance on 

data management practices at a number of different levels. The CHDN intends to keep the plan simple, 

flexible, and evolving, and to include data users in the decisionmaking process whenever possible. The 

document will undergo an initial prescribed review process that will include both an internal network 

review (i.e., by members of the technical committee and network staff), and a servicewide review that 

involves data management staff from the I&M program’s WASO office. External reviewers also will be 

sought to provide a more balanced and comprehensive review of this plan. The CHDN will update the 

plan to ensure that it accurately reflects the network’s current standards and practices. Recommendations 

for changes can be forwarded to the network data manager by any interested party or user of network 

inventory and monitoring data (e.g., park resource managers, project leaders, technicians, superintendents, 

external users). Data management and network staff will discuss these recommendations and determine 

what actions, if any, should be taken. Simple changes can be made immediately, whereas substantive 

changes will be made during version updates. Plan updates will be distributed to members of the 

network’s Technical Committee before implementation. Otherwise, the plan will be scheduled for a full 

revision and review at a minimum of every five years. The most current version of the plan is available on 

the CHDN website, http://science.nature.nps.gov/im/units/CHDN/. 
95 

6.8 Implementation 

The data management plans for each of the 32 I&M networks are the first comprehensive documents of 

their kind in the NPS, and contain practices that may be new to staff and cooperators. However, almost 

every requirement stems from federal law, Executive Orders, Director’s Orders, or national I&M program 

guidance. The DMP helps put these requirements into context and provides operational guidance for 

achieving them. The main body of the plan broadly addresses relevant subjects but directs most of the 

details into individual appendices that serve as stand-alone documents for ease of locating and retrieving 

specific information of greatest value to most users. The next plan revision should be completed within 

three years or by October 1, 2011, and every five years thereafter. Plan appendices, including SOPs, 

detailed guidelines, reference manuals, and policy statements, likely will require more frequent updates to 

account for changes in technology or availability of better information. Implementation will require 

education and training in order to familiarize park staff and cooperators with the tools, procedures, and 

guidelines outlined in the plan. Formal (training sessions) and informal (one-on-one communication and 

assistance) methods will be used. These efforts will begin in 2009 and be led, at least initially, by CHDN 

data management staff, with participation by interested parties at all parks actively encouraged. Goals for 

the first three years should include: 

• Ensuring that all staff of targeted programs and their cooperators understand the fundamentals of 

data and information management, including: 

o File management 

o Documentation 

o Quality assurance and quality control 

o Electronic storage 

o Archive storage 

• Implementing improved data management practices: 

o Accepted database design standards 

o Thorough testing of databases, data collection methods, and their integration prior to field 

work 

o Quality assurance and control procedures at every stage of project development 

• Writing common SOPs and guidance documents for multiple protocols 

• Including detailed specifications for data management, consistent with the DMP, in every vital 

signs monitoring protocol 

• Implementing procedures and outlets for communication within and among network parks and 

with the public 

Beyond the first three years, goals should include the development and assessment of: 

• Procedures to facilitate the summarization and reporting of monitoring data 

• A framework and gateway for integrating CHDN monitoring data with those of other agencies or 

networks 

• Methods for improving file management (e.g., a content-management system) and database 

administration and security (e.g., migration to SQL-Server), integrating offsite users into the 

network, and meeting other needs identified in the DMP 

Implementation and improvement of the data management system will be an ongoing process. The 

practices and procedures identified in this plan will continue to be broadly encouraged within the network 

and, in time, we expect them to be widely accepted and adopted by all CHDN park programs.

97 

Chapter 7: Data Analysis and Reporting 

This chapter summarizes our approach to analysis and reporting of monitoring data, and dissemination of 

this information to diverse audiences. Our guiding principle is to provide relevant, reliable ecological 

monitoring data that enable park staff to make appropriate management decisions and protect park 

resources. Three factors contribute to the process of maintaining a successful monitoring program: 

reliable data collection and analysis, relevant and timely information, and effective communication to 

address multiple audiences with a diverse range of information needs. 

7.1 Strategies and Key Audiences for Analysis and Reporting of 

Monitoring Results 

An essential role for the CHDN is the analysis, synthesis, and reporting of inventory and monitoring data 

and information to a wide audience, including park superintendents and other managers, park planners, 

scientists (agency and academic), interpreters, and the general public. Data and information are the 

common currency among the many different activities and people involved in the stewardship of a park’s 

natural resources. Activities such as planning, resource inventories and monitoring, research studies, 

restoration, control of invasive species, management of threatened and endangered species, fire 

management, and interpretation all either require or provide natural resource data and information to 

others. As such, the I&M program plays an integral role in the NPS’s effort to improve park management 

through greater reliance on scientific knowledge. The CHDN will work with data from many sources, 

including data collected by park staff and other programs and agencies, as well as new field data collected 

by network or park staff. The results of these analyses will be provided to multiple audiences at the local, 

regional, and national levels. 

Information quality depends on effective, appropriate analysis of high-quality data. The CHDN will 

initially ensure data quality through careful design and implementation of sampling designs and 

monitoring protocols that are supported by robust data management procedures, as described in Chapters 

4 and 6. The network will ensure that these monitoring data are effectively converted into reliable 

information about resource status and trends by emphasizing careful, detailed development of data 

analysis and interpretation as a key component of each monitoring protocol (see Section 7.2). The 

network will collaborate and coordinate with other data-collection and analysis efforts and promote the 

integration and synthesis of data across projects, programs, and disciplines. Timeliness of information 

reporting will be ensured by establishing a firm data analysis routine and schedule for each protocol, 

followed by a reporting system and schedule whereby we can effectively and promptly disseminate 

important resource information to a wide range of users. 

The CHDN recognizes that information reporting is not effectively met by a uniform approach; we have 

to meet the needs of many audiences. The primary utility for many of our products is at the park level, 

where the key role of the I&M program is to provide park managers, planners, interpreters, and other park 

staff with the information they need to make better-informed decisions and to work more effectively with 

other agencies and individuals for the benefit of park resources. These key audiences have different needs 

and desires relative to what, how, and when information is provided to them. In addition, certain data are 

needed at the regional or national level and, as stated by the National Park Advisory Board, the findings 

“must be communicated to the public, for it is the broader public that will decide the fate of these 

resources.” Figure 7.1 summarizes the major approaches to analyses and reporting tools that the CHDN 

will pursue and how they interact with outside research to support the network’s programmatic goals. 
98 

Figure 7.1 Relationships between analyses, reporting, research, and Chihuahuan Desert Network program goals 

(adapted from Chung-MacCoubrey et al. 2008). 

The CHDN vision for reporting includes the following central themes: (1) we will prepare monitoring 

reports that are understandable and useful to our primary audience: park resource managers and planners; 

(2) we will prepare reports promptly; and (3) all reports will be readily available. To achieve this vision, 

the network has adopted the following strategies: 

 The budgets and staff time allotted for each vital sign will include adequate funding to support the 

production of required annual and periodic reports. 

 All monitoring data, and all reports and information generated from monitoring data, will be 

made available promptly via the NPS Intranet. Information that does not contain sensitive or 

commercially valuable data that might jeopardize a species or resource will be made available on 

the network’s Internet website following appropriate peer review. 

 Protocols, inventory reports (as appropriate), annual data summary reports, trend reports, 

synthesis reports, and other products of the I&M efforts will be published in the NPS Natural 

Resource Report, Natural Resource Technical Report, or Natural Resource Data series, unless 

they are published in a peer-reviewed journal or a numbered report series of a collaborating 

agency or university. Reports published in these numbered series meet a set of minimum 

standards and are peer-reviewed to ensure that the information provided is scientifically credible, 

technically accurate, appropriately written for the intended audience, and designed and published 

in a professional manner. 

 The use of graphical methods for presenting data will be encouraged. 
99 

7.2 Data Analysis 

Selection of specific analytical tools for interpreting monitoring data is a function of monitoring 

objectives, assumptions regarding the target population, the spatial and temporal aspects of the sampling 

design, and the level of confidence that is desired or practical given natural and sampling variability 

(Chapter 4, McBean and Rovers 1998, Thompson et al. 1998, Artiola et al. 2004). Each monitoring 

protocol will contain detailed information on analytical tools and approaches for data analysis and 

interpretation, including rationales for a particular approach, advantages and limitations of each 

procedure, and standard operating procedures for each prescribed analysis (Oakley et al. 2003, Chapter 5, 

Appendix J). 

Four general levels of data analysis are anticipated during implementation of our monitoring protocols 

and program: (1) descriptive and summary statistical analysis, (2) determination of conditional status for a 

monitored resource, (3) determination of trends in condition over time for a monitored resource, and (4) 

synthesis of status and trend information across multiple resources over time to depict larger-scale aspects 

of ecosystem health and function (Table 7.2). Descriptive analysis may be performed at any time 

following data collection and entry. Status and trends analysis will be performed on protocol-specific 

schedules. Larger-scale synthesis across multiple resources and monitoring efforts will occur only after 

adequate amounts of data have become available for all considered resources and variables. In addition, 

trend analysis and synthesis can only occur after appropriate time has passed to adequately capture 

temporal scales of considered phenomena. Long-term trend reports and syntheses will be subject to peer 

review, as appropriate. 

Data analysis may be performed by different people, including the network ecologist, program manager, 

and data manager, as well as key project leads (e.g., when assessing monitoring data related to water 

quality and quantity or air quality). GIS specialists and/or associated technicians and interns also will be 

involved with various aspects of data collection and analysis. Generally, analysis will be supervised and 

coordinated by the network ecologist or project leads assigned to a particular protocol. Overall program 

oversight will be provided by the network program manager. 

7.3 Communications and Reporting 

To effectively communicate monitoring information and results with a variety of audiences, analysis and 

interpretation must occur on a regular basis, and results must be communicated in formats specific to 

intended audiences. With the assistance of a Cooperative Ecosystem Studies Unit (CESU) cooperator at 

Colorado State University and the NPS-Natural Resource Program Center, the CHDN will develop a 

science communication plan that identifies natural resource education and communications techniques to 

be used for internal and external audiences. 

CHDN reporting mechanisms are based on national guidance, have been modified to fit network needs, 

and fall into four categories: programmatic, protocol-related, science communication, and 

interpretation/outreach. The categories listed below are described in the following sections and Table 7.3-

1. Each monitoring protocol will also contain additional and specific information on data summary, 

analysis, and reporting requirements and procedures. 

1. Annual reports for specific protocols and projects 

2. Annual briefings to park managers 

3. Resource briefs 

4. Analysis and synthesis reports 

5. Protocol and program reviews 

6. Natural resource summary table 

7. Scientific journal articles and book chapters, and presentations at scientific meetings 

8. Network Internet and Intranet websites 

9. Learning Center of the American Southwest. 
100 

Table 7.2. Four general approaches to data analysis for Chihuahuan Desert Network vital signs, 

and the lead analyst responsible. 

Type of 

analysis Description Lead analyst and support 

Data 

summarization/ 

characterization 

 Calculation of basic statistics from monitoring data, 

including measures of location and dispersion. 

 Summarization that encompasses measured and derived 

variables specified in the monitoring protocol and forms 

the basis of more comprehensive analyses and for 

communication of results in both graphical and tabular 

formats. 

Lead: Project lead 

Support: Network program 

manager or ecologist and data 

management staff. 

Status 

determination 

 Analysis and interpretation of the ecological status (point 

in time) of a vital sign to address the following types of 

questions: 

o How do observed values compare with historical 

levels? 

o Do observed values exceed a regulatory 

standard, or a known or hypothesized ecological 

threshold? 

o What is the spatial distribution (within park, 

network, ecoregion) of observed values for a 

given point in time? 

o Do these patterns suggest directional 

relationships with other ecological factors? 

 Status determination will involve expert interpretation of 

both the basic statistics and statistical analysis. 

 Assumptions about the target population and the level of 

confidence in the estimates will be ascertained during the 

analysis. 

Lead: Network program 

manager or ecologist and/or 

principal investigator (PI) for 

protocol 

Support: Other network staff, 

cooperators, interns, subjectmatter experts 

Trends 

evaluation 

 Evaluations of trends in vital signs will address the 

following questions: 

o Is there directional change in a vital sign over the 

period of measurement? 

o What is the rate of change, and how does this 

pattern compare with trends over broader spatial 

scales and known ecological relationships? 

 Analysis of trends will employ parametric, nonparametric, 

or mixed models based on assumptions made about the 

target population. Where appropriate, exogenous variables 

(natural, random phenomena that may influence the 

response variable) will be accounted for in the analysis. 

Lead: Network program 

manager or ecologist and/or PI 

for protocol 

Support: Other network staff, 

cooperators, or interns 
Table 7.2. Four general approaches to data analysis for Chihuahuan Desert Network vital signs, and the lead 

analyst responsible, cont. 

101 

Type of 

analysis Description Lead analyst and support 

Synthesis and 

modeling 

 Examination of patterns across vital signs and ecological 

factors to gain broad insights on ecosystem processes and 

integrity. Analyses may include: 

o Qualitative and quantitative comparisons of vital 

signs with known or hypothesized relationships; 

o Data exploration and confirmation (e.g., 

correlation, ordination, classification, multiple 

regression, structural equation modeling); 

o Development of predictive models. 

 Synthetic analysis has potential to explore ecological 

relationships in the context of vital signs monitoring and 

will require close interaction with academic and agency 

researchers. 

Lead: Network program 

manager or ecologist (data 

synthesis and modeling); PI 

for protocol 

Support: Cooperators, 

partners, or other network staff 
102 

Table 7.3-1. Summary of proposed products for the Chihuahuan Desert Network. 

Report type Purpose Primary audience(s) Frequency Review Programmatic reports Annual administrative report and work plan 

 Accounts for funds and FTE 

expended 

 Describes highlights, objectives, 

tasks, accomplishments, and products 

 Provides an administrative history 

of the network 

BOD, TC, other park and network staff, regional and national I&M program managers 

Annual Reviewe

approveprogram program 

Monitoring program review 

 Formally reviews operations and 

results at 5-yr intervals 

 Implements the quality assurance 

and peer-review process 

Superintendents, park resource staff, CHDN staff, national program managers, external scientists, partners 

5-year intervals BOD & T

administIMR and 

Protocol-related reports Specific protocol development and pilot projects 

 Provide background and methods 

of protocol development 

 Provide record of decision for 

protocol design 

 Document results of pilot studies 

Network staff, park professional staff, TC, scientific cooperators, other networks with shared vital signs 

As completed FY10–FY13 

Peer-rev

Annual reports for each protocol 

 Summarize annual data and 

document monitoring activities for 

the year 

 Describe status of the resource  Document changes in monitoring 

protocols 

 Communicate monitoring efforts to 

parks 

Superintendents, park resource, managers, CHDN staff, national program managers, external scientists and partners 

Annual Peer-rev
Table 7.3-1. Summary of proposed products for the Chihuahuan Desert Network, cont. 

103 

Report type Purpose Primary audience(s) Frequency Review Trend analysis and synthesis reports 

 Determine patterns/trends in 

resource condition 

 Identify new characteristics of 

resources and correlations among resources 

 Interpret data within park, multipark, network, and regional 

contexts 

 Recommend changes to 

management (feedback for adaptive management) 

Superintendents, park resource managers, CHDN staff, external scientists 

3–5-yr intervals for resources sampled annually

Peer-rev

Summary of trend reports 

Summarize comprehensive trend analysis and synthesis reports to highlight key findings and recommendations 

Superintendents, park resource managers, interpreters, general public 

Commensurate with frequency of Comprehensive Reports 

Peer-rev

Protocol review report Reviews procedures of individual 

protocols; determines where actual procedures fall short or expectations suggest revisions 

BOD, TC, park resource managers, network staff, servicewide program managers, external scientists 

Within 1–3 years of protocol implementation; thereafter, dependent on monitoring “cycle” that varies by protocol 

Internal peer revnecessa

CHDN vital signs program report 

 Describe current conditions of park 

resources 

 Report interesting trends and 

highlights of monitoring activities 

 Identify situations of concern  Explore future issues and 

directions 

Superintendents, park resource managers, network staff, external scientists, public 

Annual Internal 
Table 7.3-1. Summary of proposed products for the Chihuahuan Desert Network, cont. 

104 

Report type Purpose Primary audience(s) Frequency Review Science communicationsScientific journal articles & book chapters 

 Make scientific contributions to 

ecological and monitoring science 

 Subject I&M activities and 

approaches to unbiased peer review 

 Elevate scientific standing and 

authority of program 

Park resource managers, network staff, external scientists 

Varies Peer-rev

editor 

Symposia, workshops, and conference presentations 

 Review and summarize information 

on specific topics 

 Communicate latest findings to 

peers 

 Identify emerging issues and 

generate new ideas 

 Expose I&M activities to regional or 

national scientific community 

 Elevate scientific standing and 

authority of program 

Other federal and state agencies, 

academics, NGOs, and other external scientists; park and network staff 

Variably as material becomes available 

Generalpresenta

Interpretation and outreach Resource briefs  For each protocol, report activities 

and explain the significance and relevance of the scientific findings in non-technical manner 

 Provide short, digestible synthesis 

of vital sign monitoring results on status and trends of resource condition

Superintendents, park resource managers, interpreters, public

Varies Peer-rev

Internet and Intranet Websites 

 Improve public awareness through 

web presence 

 Centralize repository of all final 

reports to ensure products are easily accessible in commonly used electronic formats 

 Facilitate internal distribution of 

NPS documents 

Superintendents, park resource managers, CHDN staff, national program managers, scientific community, general public 

As reports are finalized 

Only revwithout sbe poste
Table 7.3-1. Summary of proposed products for the Chihuahuan Desert Network, cont. 

105 

Report type Purpose Primary audience(s) Frequency Review Learning Center of the American Southwest 

 Provides a one-stop portal to view 

resource information for 49 park units and four I&M networks across a six-state area 

 Explains the need for and results of 

research and monitoring to a variety of science-oriented audiences and the interested public

 Promotes mission-oriented 

research within the region

Superintendents, park resource managers, interpreters, CHDN staff, national program managers, scientific community, general public

As products are finalized 

Only revwithout sbe poste
106 

7.3.1 Annual reports for specific protocols and projects 

The primary purposes of annual reports for specific protocols and projects are to: 

 summarize and archive annual data and document monitoring activities for the year; 

 document changes in monitoring protocols; 

 increase communication within the park and network; and 

 describe the current condition of the resource. 

The primary audiences for these reports are park superintendents and resource managers, network staff, 

park-based scientists, and collaborating scientists. Most annual reports will receive peer review at the 

network level, although a few may require review by subject-matter experts from universities or other 

agencies. Many of our monitoring protocols involve annual data collection, and those protocols will 

generate an annual report each year (Table 7.2). However, some sampling regimes do not involve 

sampling every year. Those projects will produce “annual” reports only when there are significant 

monitoring activities to document. Wherever possible, annual reports will be based on automated data 

summarization routines built into the MS Access database for each protocol. The automation of data 

summaries and annual reports will facilitate the network’s ability to manage multiple projects and 

produce reports with consistent content from year to year at timely intervals. For analyses beyond simple 

data summaries, data will first be exported to external statistical software. 

7.3.2 Annual briefings to park managers 

Each year, in an effort to increase the availability and usefulness of monitoring results for park managers, 

the network program manager will take the lead in organizing a one-day science briefing for park 

managers (possibly in conjunction with a Board of Directors meeting) in which network staff, park 

scientists, USGS scientists, collaborators from academia, and others involved in monitoring the parks’ 

natural resources will brief managers on the highlights and potential management action items for each 

protocol or discipline. These briefings may include park staff and collaborators from other programs and 

agencies to provide managers with an overview of the status and trends in the high-priority vital signs 

being monitored by the CHDN. Unlike typical presentations intended for the scientific community, 

someone representing each protocol, program, or project will be asked to simply identify key findings or 

“highlights” from the previous year’s work, and to identify potential management action items. The 

scientists will be encouraged to prepare a 1- or 2-page resource brief or other short briefing statement that 

summarizes the key findings and recommendations for their protocol or project. 

7.3.3 Resource briefs 

The CHDN will develop resource briefs for the 10 protocols it is implementing and, possibly, for other 

vital signs (if appropriate), and will encourage parks and collaborating scientists to do so, as well. The 

resource brief or other short briefing statement summarizes the key findings, status and trends, and 

recommendations for the protocol or project. 

7.3.4 Analysis and synthesis reports 

The role of analysis and synthesis reports is to: 

 determine patterns/trends in condition of resources being monitored; 

 identify new characteristics of resources and correlations among resources being monitored; 

 analyze data to determine the amount of change that can be detected by a given type and level of 

sampling; 

 interpret data for a park within a multi-park, regional, or national context; and 

 recommend changes to management of resources (i.e., feedback for adaptive management). 
107 

The primary audiences for these reports are park superintendents and resource managers, park-based 

scientists, network staff, and collaborating scientists. These reports will receive peer review by at least 

three subject-matter experts. Analysis and synthesis reports can provide critical insights into resource 

status and trends, which can then be used to inform resource management efforts and regional resource 

analyses. This type of analysis, more in-depth than that of the annual report, requires several seasons of 

sampling data. Therefore, these reports are usually written at intervals of 3–5 years for resources sampled 

annually, unless there is a pressing need for the information to address a particular issue. For resources 

sampled less frequently, or that have a particularly low rate of change, intervals between reports may be 

longer. 

7.3.5 Protocol and program reviews 

Periodic program reviews are an essential component of quality assurance for any long-term monitoring 

program. The servicewide I&M program office will organize and lead a review of the CHDN monitoring 

effort approximately three years after this monitoring plan has been approved and implemented. 

Subsequent reviews of the program will occur at approximately five-year intervals. Topics to be 

addressed during the program review include program efficacy, accountability, scientific rigor, 

contribution to adaptive park management and larger scientific endeavors, outreach, partnerships, data 

management procedures, and products. These reviews cover monitoring results over a longer period of 

time, as well as program structure and function, to determine whether the program is achieving its 

objectives and whether the list of objectives is still relevant, realistic, and sufficient. 

7.3.6 Natural resource summary table 

“Connect the Dots” is a strategic, long-term framework developed and supported by multiple individuals 

and programs at the park, network, regional, and national levels, to better connect science to park 

management through the planning process. Coordination and integration between scientists, planners, and 

park managers is facilitated through use of a “Natural Resource Summary Table” developed for each 

network park, which will eventually become a key source of summarized information for a park’s 

Resource Stewardship Strategy. Tables established by the CHDN for each park 

(http://www1.nrintra.nps.gov/im/units/chdn/monitor/index.cfm) are to be used as a long-term framework 

for coordinating the efforts of the network, Natural Resource Condition Assessment program, park 

planning, park-funded monitoring and research relevant to assessing natural resource condition, and 

research and monitoring efforts related to natural resource condition conducted by NPS Natural Resource 

Program Center divisions and other agencies. This framework allows multiple programs, individuals, and 

funding sources to assist the park in populating the table as opportunities arise. 

7.3.7 Scientific journal articles, book chapters, and presentations at scientific 

meetings 

The publication of scientific journal articles and book chapters is done primarily to communicate 

advances in knowledge and is an important and widely recognized means of quality assurance and quality 

control. Putting a program’s methods, analyses, and conclusions under the scrutiny of a scientific 

journal’s peer-review process is basic to science and one of the best ways to ensure scientific rigor. 

Network staff, park scientists, and collaborators will also periodically present their findings at 

professional symposia, conferences, and workshops as a means of communicating the latest findings with 

peers, identifying emerging issues, and generating new ideas. 

All journal articles, book chapters, and other written reports will be listed in the network’s annual 

administrative report that is provided to network staff, the Technical Committee, Board of Directors, and 

regional and national offices each year. Additionally, all scientific journal articles, book chapters, and 

written reports will be entered into the NatureBib bibliographic database maintained by the network. 
108 

7.3.8 Network Internet and Intranet websites 

Websites are a key tool for promoting communication, coordination, and collaboration among the many 

people, programs, and agencies involved with the network monitoring program. The 32 I&M networks 

are required to develop and maintain a parallel series of Intranet (NPS only) and Internet (Public) 

websites to be used as a key means of communicating and disseminating inventory and monitoring results 

to park managers, planners, interpreters, and other internal and external audiences. Network staff will use 

these websites as a primary means of making resource briefs, data summaries, progress reports, technical 

reports, trend reports, interpretive materials, and other information available to internal and external 

audiences. 

All written products of the monitoring effort, unless they contain sensitive or commercially valuable 

information that needs to be restricted, will be posted to the main network website, 

http://science.nature.nps.gov/im/units/chdn.

7.3.9 Learning Center of the American Southwest 

The CHDN, along with Sonoran Desert, Southern Colorado Plateau, and Southern Plains networks and 

many external partners, is helping to develop the Learning Center of the American Southwest. The 

primary focus of the Learning Center is to explain the need for and results of research and monitoring to 

land managers, students, researchers, policymakers, and the interested public, and promote missionoriented research within the region. This website will serve as a one-stop portal to view resource 

information for 49 national park units and four I&M networks across a six-state area. The website will be 

especially useful for park interpreters developing their programs. 
109 

Chapter 8: Administration and Implementation 

This chapter describes the CHDN plan for administering the monitoring program. The network has 

developed a near-term (3–5-year) plan under which protocols will be implemented and monitoring will 

begin. In this chapter, we describe the core duties of the network, the makeup of the Board of Directors 

and Technical Committee, the network decisionmaking process, the staffing plan, how network 

operations are integrated with other park operations, key partnerships, and the periodic review process for 

the program. 

8.1 Core Duties 

The WASO office provided guidance regarding activities that are considered “core” to I&M networks and 

those considered secondary of nature in the document, “Updated Guidance Relative to the Ongoing 

Operation and Maintenance of Vital Signs Monitoring Networks,” which accompanied Memorandum 

N16 (2370), from Associate Director Mary Foley, on February 28, 2008. The following is excerpted from 

that document: 

As defined in the Natural Resource Challenge, the primary mission of the monitoring 

networks is to collect, manage, analyze, and report long-term data for a modest set of 

vital signs (measurements of resource condition), and to effectively deliver those data and 

related information on resource conditions to local park managers, planners, interpreters, 

and other key audiences. Fundamentally, network personnel are expected to devote the 

majority of their time and effort to completing tasks associated with that mission. Their 

FTEs were requested from OMB and have been assigned to the networks for that 

purpose. Chief among the network responsibilities that must be performed are the 

following: 

 Providing “one stop shopping” for resource condition and trend 

information. For the high-priority vital signs identified in the network’s 

monitoring plan and currently being monitored, this should be thought of as 

“the” core network function. Accordingly, network staff should maintain 

Intranet and Internet websites (see below) as the key means of 

communicating data and information collected and organized by the network 

to park managers, planners, and park staff for decisionmaking, education, 

and research. 

 Synthesizing key findings in succinct statements for managers and 

planners. This likewise is considered a core network function, especially for 

network priority vital signs. Network staff should place priority on 

developing resource briefs and technical documents for each vital sign, and 

preparing synthesis reports that analyze data across vital signs, as well as 

data from other sources and disciplines, to help interpret results of vital signs 

monitoring. In addition, priority should be given to posting these reports on 

the network’s websites to ensure their availability to all interested parties. 

 Collaboration with other programs and agencies. As noted above, 

collaboration and coordination with other programs and agencies has always 

been considered to be a primary function of monitoring networks. However, 

lower priority is justified in those instances in which the collaboration and 

coordination efforts do not directly contribute to accomplishing the 

network’s core mission. 
110 

 Organizing and cataloging data collected by others. The task of 

collecting, organizing, and cataloging data collected by others (i.e., nonnetwork) should be considered to be a core function of the network, to the 

extent that the data are applicable to the high-priority vital signs being 

monitored by the network. 

Other activities in which the network may play an assisting or secondary (but not lead) role include 

assisting in occasional resource assessments, reporting to GPRA and Land Health Goals, defining desired 

resource conditions based on current status and trend, and providing materials to interpreters, educators, 

and the general public. 

8.2 Board of Directors 

The Chihuahuan Desert Network I&M program is accountable to the parks through the Board of 

Directors (BOD or “board”) and Technical Committee (TC), as well as to the Office of Management and 

Budget, Congress, and the taxpayers through oversight by the BOD, regional I&M program manager, and 

servicewide I&M program manager. The CHDN BOD includes the superintendent from each network 

park, the Intermountain Region I&M program manager, the network program manager, and chair for the 

TC (Table 8.2). One of the superintendents serves as board chair and one serves as vice chair. A new 

chair and vice chair are selected annually, with the vice chair becoming chair the following fiscal year. 

The superintendents and regional program manager are the voting members of the board, and the other 

members serve as advisors. A charter (Appendix L) for the BOD, updated and approved in 2007, guides 

the function and operation of the board. 

The CHDN board is responsible for ensuring the overall effectiveness and success of the network’s 

monitoring efforts and for ensuring that funds are spent for their intended purposes. The Board makes 

decisions about the development and implementation of the network’s monitoring strategy, including 

approval of annual budgets, work plans, and network staffing plans, and promotes overall accountability 

for the network monitoring program. The BOD is committed to operate in and foster an atmosphere of 

fairness, trust, selflessness, and respect. A key feature of the charter is that all decisions are made by 

consensus. As described in the network charter, the major responsibilities of the BOD are to: 

 Provide leadership to conduct a credible I&M program for the benefit of the network. 

 Promote accountability and effectiveness for the I&M program by reviewing progress and 

ensuring quality control for the networks. 

 Provide guidance to the TC and resource management staffs in the network for the design and 

implementation of inventories, vital signs monitoring, and other management activities related to 

the Natural Resource Challenge. 

 Establish strategies and procedures for leveraging network funds and personnel to best 

accomplish the inventory, monitoring and other resource needs of network parks. 

 In concert with the CHDN program manager, review the staffing plan, and coordinate and 

approve the commitment of existing park personnel, facilities, and equipment to I&M programs 

and activities. 

 Provide input and secondary review to the midseason and annual performance appraisals of the 

network program manager. 

 Seek additional funding from other sources to leverage the funds provided through the 

servicewide program. 

 Solicit professional guidance from and partnerships with other individuals and organizations. 
111 

Table 8.2. Composition of the Chihuahuan Desert Network Board of Directors (as of March 2010). 

Title, Park Name Voting member Ex-officio 

Superintendent, AMIS Alan Cox X 

Superintendent, BIBE Bill Wellman X 

Superintendent, CAVE John Benjamin X 

Superintendent, FODA John Morlock, Chair X 

Superintendent, GUMO John Lujan X 

Superintendent, WHSA Kevin Schneider X 

IMR Program Manager Bruce Bingham X 

Chief, Natural Resources and Interpretation, 

GUMO 

Fred Armstrong, TC Chair X 

Research Coordinator, DS-CESU Larry Norris X 

CHDN Program Manager Kirsten Gallo X 

8.3 Technical Committee 

The BOD, TC, and CHDN staff work together to develop and implement the monitoring program. The 

BOD is the final decisionmaking body and is accountable for the entire network. The TC provides 

technical assistance and advice to the board. Permanent TC members consist of at least one representative 

of the resource management staff for each park (usually the chief), as delegated by the superintendent 

(Table 8.3). One of the permanent voting members serves as the TC chair and one serves as vice chair. A 

new chair and vice chair are selected annually, with the vice chair becoming chair the following fiscal 

year. The network program manager serves as an ex-officio member of the TC. Additional key ex-officio 

members of the committee include the network data manager, network ecologist, regional fire ecologist, 

and CHDN and SOPN exotic plant management team leader. Other relevant resource staff from network 

parks are also invited to participate in TC meetings, depending on the circumstances. 

Other key cooperators, members of the academic community, and representatives from other federal 

agencies are involved in development of conceptual models, monitoring protocols, and water quality 

monitoring plan. These ad hoc advisors to the TC are not considered permanent members, but play an 

important role in providing technical expertise to the TC and BOD. 
112 

Table 8.3. Composition of the Chihuahuan Desert Network Technical Committee. 

Title, Park Name Voting member Ex-officio 

Chief, Education & Resource Management, AMIS Greg Garetz X 

Chief, Science & Resource Management, BIBE Phil Wilson X 

Chief, Resource Stewardship & Science, CAVE Kent Schwarzkopf X 

Chief of Interpretation, FODA John Heiner X 

Chief of Resources & Interpretation, GUMO Fred Armstrong, Chair X 

Chief, Science & Resource Management, WHSA David Bustos X 

Program Manager, CHDN Kirsten Gallo X 

Data Manager, CHDN Tom Richie X 

Science Advisor, CHDN Hildy Reiser X 

Regional Fire Ecologist, BIBE Richard Gatewood X 

CHDN/SOPN EPMT Leader, CAVE Vacant X 

Current as of March 2010. 

8.4 Staffing Plan 

In accordance with servicewide I&M goals, network activities revolve around five program functions: 

1. Conducting baseline inventories of natural resources in network parks (including those currently 

underway: vegetation mapping, soils mapping) and fulfilling other critical inventory needs of 

network parks. 

2. Implementing and conducting an integrated, scientifically credible, long-term ecological 

monitoring program to efficiently and effectively monitor status and trends of selected vital signs. 

3. Implementing and conducting data management and decision support systems, including GIS and 

other tools, to aid park managers in identifying, implementing, and evaluating management 

options. 

4. Integrating inventory and monitoring programs with park planning, maintenance, interpretation, 

and visitor-protection activities to help the parks in their efforts to make natural resource 

protection even more of an integral part of overall park management. 

5. Cooperating with other agencies and organizations to share resources, achieve common goals, 

and avoid unnecessary duplication of effort and expense. 

The network staffing plan is designed to support these functions and provide park managers with the 

professional expertise needed to implement a successful inventory and monitoring program. The staffing 

plan is designed with the goal of keeping fixed costs, such as permanent staff, vehicles, and office space, 

at or below 60% of the network budget during the first five years of implementation (FY2009–FY2013), 

to allow flexibility in partnerships and data acquisition. We do not expect the majority of monitoring data 

to be collected by permanent network staff. Shorter-term technical and field-data collection positions will 

be filled by NPS seasonals hired by CHDN, cooperative agreements with other state and federal agencies 

and universities, students, interns, and volunteers from the Student Conservation Association. Currently, 

the core permanent network staff consists of a program manager, science advisor, and a data manager. A 

permanent full-time field coordinator will soon be added to the team (Table 8.4). Short descriptions of 

these and other positions follow. 
113 

Table 8.4. Current and proposed Chihuahuan Desert Network staff positions and their primary 

duties. 

Position Primary duties % of time 

Current 

Provides direction and manages overall planning and implementation of the 

network I&M program 35%

Coordinates project-specific acquisition, data analysis, summary, and reporting 30%

Ensures that information is provided to parks and partners in useful formats 15%

Coordinates I&M partnerships 5%

Provides program oversight and supervision 10%

Program Manager 

GS-13, Permanent 

Provides field assistance as needed 5%

Provides guidance, oversight, and management of collaborative resource 

science and management programs between the parks and the network 50%

Conducts project-specific data analysis, summary, and reporting on 

collaborative projects as needed or time allows 15%

Works with program professionals to provide information to parks and partners 

in useful formats and assist parks with implementing sound reporting practices 

and data management 

15%

Coordinates with regional office and WASO to complete the 12 basic 

servicewide inventories funded by the servicewide I&M program 

15%

Science Advisor

GS-13, Permanent 

Provides field assistance as needed 5%

Conducts data validation, dissemination, and archiving; database development; 

overall QA/QC for the network program 50%

Works with ecologists to ensure that information is provided to parks and 

partners in useful formats 20%

Implements data management partnerships 10%

Provides oversight and supervision for data management activities, ensures 

CHDN program meets regional and national data management policies 10%

Data Manager 

GS-11, Permanent 

IT collateral duties include the installation, configuration and maintenance of 

network components, servers, workstations, etc. 10%

Oversees field crews, including arranging training and ensuring crew safety; 

completes QA/QC for implementation of field components of monitoring 

protocols; coordinates field logistics; maintains equipment 

70%

Assists data manager with data entry and QA 10%

Assists program manager and/or ecologist with compiling data summaries 10%

Works with legacy datasets and synthesizes a wide variety of published and 

unpublished material in support of the CHDN monitoring program 5%

Field Coordinator 

GS7/9, Permanent 

(to begin in 

CY2010) 

Assists other CHDN staff with development of monitoring products 5%
Table 8.4. Current and proposed Chihuahuan Desert Network staff positions and their primary duties, cont. 

114 

Position Primary duties % of time 

Performs budget tracking, reporting, programming in AFS3, fiscal year-end 

accrual preparation, employee credit card statements, etc. 5% Budget Analyst1

GS-9, Permanent 

Monitors accounts and provides general support for payroll (FFS); expense and 

credit card adjustments; entering fiscal year-end accruals; AFS3 programming 

support, including financial plans; BCP module programming and outputs; 

IDEAS budget approvals 

8%

Payroll preparation – time and attendance, personnel action preparation and 

submittal, SF-182 prep, etc. 3%

Procurement (e.g., equipment, upgrades, large & small supplies, professional 

services invoices, IA's, CA's, etc.) 3%

Administrative 

Assistant2

GS-5, Term (to 

begin in CY 2010) 

Travel management (authorizations, vouchers) 9%

Proposed 

Designs, develops, and tests monitoring protocols 

Directs data collection procedures 

Conducts data analysis and reporting 

Ecologist 

GS-9/11, permanent 

Reports significant findings to park managers and interested public 

Develops procedures for compiling, utilizing, and disseminating spatial data 

Manages, documents, and distributes spatial data resulting from I&M projects 

Works with park staff to build and maintain a library of relevant park spatial data 

Provides GPS assistance and training to staff and cooperators as needed 

Serves as a co-investigator on landscape monitoring projects 

GIS Specialist 

GS-7/9, Term 

Acts as program liaison with GIS providers to ensure appropriate development 

of spatial data layers, and integration of monitoring datasets and coverages 

Updates, maintains, and coordinates the certification process for the NPSpecies 

database 

Maintains the CHDN websites, writes and manages their content 

Works with data manager to design, build, and maintain project databases, NPS 

servicewide databases, GIS, digital document libraries, and information 

distribution system 

GIS/Data 

Management Tech 

GS-5/6/7, TermSCEP 

Assists with maintaining spatial datasets with metadata and performing GIS 

analysis 

1

This position is shared with 4 other IMR I&M networks; CHDN share is 0.007 FTE. 

2

This position is shared with 6 other IMR I&M networks; CHDN share is 0.12 FTE. 
115 

8.4.1 Program manager 

The program manager provides overall direction for the CHDN I&M program. The program manager 

works with network parks, the TC, BOD, and the Intermountain Region I&M coordinator to develop 

inventory and monitoring strategies and recommend implementation schedules for funding and staffing 

consideration. This position coordinates project-specific data analysis and reporting and ensures that 

information is provided to park managers in useful formats. The program manager supervises the CHDN 

professional-level positions and provides general oversight and accountability for the network program. 

8.4.2 Science advisor 

This position serves as the primary contact between WASO and IMR natural resources science and 

management programs in network parks. This includes coordination and support for resource inventories; 

planning and stewardship projects; cooperative projects and research involving other agencies or 

universities; and other cooperative WASO, regional, network, and park-level initiatives and projects. The 

science advisor also coordinates with the regional office and WASO to complete the 12 basic servicewide 

inventories funded by the I&M program, and other high-priority natural resource inventories identified by 

the parks. The science advisor assists parks in evaluating and applying research and management project 

results, participates in ecosystem management planning and partnerships as required, and works 

cooperatively with conservation partners involved in the preservation of natural resources. 

8.4.3 Data manager 

The data manager has a central role in ensuring that project data conform to program standards, designing 

project databases, disseminating data, and ensuring long-term data integrity, security, and availability. In 

order to maintain high data-quality standards and promote ready use of project data, the data manager 

collaborates with the ecologist and/or project managers to develop data entry forms, QA/QC procedures, 

and automated reports. The data manager also coordinates all information technology (IT) activities and 

collaborates with university and other agency computer support personnel. Because of the small size of 

the CHDN staff, the data manager also performs IT collateral duties that include the installation, 

configuration, and maintenance of network components, servers, workstations, peripheral equipment, 

software, and other services used by the network. Additionally, these duties include IT security and 

compliance with the U.S. Department of the Interior (DOI) Security Handbook (USDOI 2008). 

8.4.4 Field coordinator

The field coordinator has the primary responsibility for overseeing the monitoring field crews, including 

hiring, training, and supervising crew members and ensuring their safety in the field. This individual 

plans and provides for field equipment and logistics, helps the data manager to input data and conduct 

quality control, and collaborates with the ecologist and other project managers on data summary reports. 

He/she updates, maintains, and coordinates the certification process for the NPSpecies database and 

maintains CHDN content on the Learning Center for the American Southwest website (see Table 8.4). 

8.4.5 Budget analyst 

The budget analyst provides administrative and budget support services to all seven Intermountain Region 

I&M networks, including the CHDN. Primary duties are budget tracking and budget analyst support, 

including credit card processing (i.e., responsible as Reviewing Official, verifying that all transactions are 

documented properly, meet credit card policy and guidelines, and are listed on the credit card purchase 

log, and that copies of all receipts are attached, if applicable). Other responsibilities include acting as a 

liaison between all I&M networks and the IMR regional property management team and assisting with 

purchasing and contracting. 
116 

8.4.6 Administrative assistant 

The administrative assistant provides administrative and budget support services to five Intermountain 

Region I&M networks, including the CHDN. Primary duties are (1) time and attendance (i.e., maintain 

time and attendance files and documentation for audit purposes for each pay period), (2) travel processing 

(i.e., review each authorization to ensure it meets with Federal Travel Regulations and NPS policy and 

procedures to the best of his or her knowledge and that trip purposes and details are entered 

appropriately), and (3) purchasing. 

8.4.7 Ecologist 

The ecologist provides statistical and analytical support to network monitoring projects and coordinates 

the pilot testing and implementation of monitoring protocols. The ecologist develops sound analytic 

approaches and inference strategies, conducts data validation and verification, works with cooperators, 

oversees field data collection, and conducts analysis and reporting. The ecologist also coordinates and 

supports partnerships and works with program professionals to provide information to parks and partners 

in useful formats. 

8.4.8 GIS specialist 

The GIS specialist is responsible for managing the network’s spatial data and providing GIS support to 

network I&M projects. The GIS specialist will compile and refine relevant park spatial data, including 

that for the 12 basic inventories and other network-sponsored inventories. This person works with the data 

manager to develop infrastructure, procedures, and policies for utilizing and disseminating spatial data 

from I&M activities, works with the network program manager and other staff to support spatial aspects 

of protocol development (e.g., sample frame delineation and site selection), and works with network staff 

and cooperators to develop a landscape monitoring protocol. This individual is also a program liaison 

with GIS providers to ensure appropriate development of spatial data layers and integration of monitoring 

datasets and metadata. The GIS specialist works with the data manager to disseminate spatial data to park 

managers, cooperating agencies, and scientists. 

8.4.9 GIS/Data management technician 

The Geographic Information System (GIS)/Data Management Technician assists with information 

requests, both internal and external. Core duties are database development, developing and maintaining 

the CHDN Internet and Intranet sites, and GIS data management and manipulation. This position will 

help with digital data collection and transfer, data manipulation, data visualization, and data archiving and 

storage. This position is a term position to ensure that new technologies are applied to existing I&M 

programs as software and hardware advance. Having this position rotate over time will provide 

experience transfer from those trained with the latest and most innovative software and hardware to the 

institutional knowledge built on the core staff. This position will not only provide GIS support, but will be 

an integral member of the data management team. 

8.4.10 University interns and other associated positions 

In addition to the staff (current and proposed) listed in Table 8.4, the network currently has one student 

intern from New Mexico State University assisting with data management and program support. The 

CHDN maintains an agreement with New Mexico State University for office space, GIS assistance, and 

both undergraduate and graduate student interns. Interns have assisted the network with data management 

activities, data mining, and computer programming tasks. 
117 

8.4.11 Field efforts 

CHDN fieldwork will represent a continuum of efforts ranging from work conducted entirely in-house 

(by park and CHDN staff) to work performed by cooperators and partners. In some cases, the CHDN will 

obtain data from external sources at no cost—for instance, data collected by the National Weather 

Service. The completed protocols, including analysis of potential sources, alternatives, and costs of field 

monitoring, will identify which fieldwork will be done by the network and which by outside partners. 

Worker safety is paramount for CHDN field efforts (as for all CHDN operations). The CHDN will 

operate in accordance with all safety laws and regulations and DOI and NPS policies. Each CHDN 

protocol will include a safety-related SOP and identify necessary safety training and equipment for 

fieldworkers. Depending on the park and protocol, training will include backcountry safety and first aid, 

and DOI watercraft safety. The CHDN will cooperate with network parks to coordinate safety training for 

field staff and park seasonal staff. CHDN planning and budgets will include safety training and 

equipment. 

8.5 Program Integration 

Integration with park operations will be an important component of this program. Data, summaries, and 

reports will be made available to all park operations, including resource management, interpretation, law 

enforcement, and maintenance. Most network parks already integrate cultural and natural resource 

management activities. We have selected vital signs and monitoring approaches with the purpose of 

providing data that can be used by the parks, and that will allow for assessment of vital signs across the 

network. Where possible, we also are striving to make data summaries available to other agencies within 

the Chihuahuan Desert Ecoregion, especially those organizations that are monitoring the same or similar 

resources on the lands they manage. 

Network parks have indicated their ability to provide housing for field crews, transportation to monitoring 

sites, and other assistance to the network. Except in limited circumstances, the network parks are unable 

to have park personnel conduct monitoring of network vital signs. One-page information sheets will be 

developed (via an agreement between NPS, Natural Resource Program Center, and Colorado State 

University) for each park to show what the network is monitoring and why. The CHDN I&M program 

office is based on the campus of New Mexico State University in Las Cruces, New Mexico. The program 

offices are only 50 minutes from one of the network parks (WHSA), and three hours or less drive time 

from the majority of its parks. Park visits by network staff, and regularly scheduled meetings, will be 

important for developing greater integration into park operations. As field work begins and data are 

collected, more integration with park staffs will be possible. Opportunities to help all park divisions will 

be actively sought. Participation by park personnel on the network’s BOD and TC further helps to 

integrate the network’s planning with the parks’ concerns and activities. 

8.6 Partnerships 

Cooperative agreements and partnerships inside and outside the NPS will be important to the 

implementation of the CHDN monitoring program. A collaborative effort between CHDN, the Sonoran 

Desert Network, and Southern Plains Network is underway for several protocols. For example, the CHDN 

is adopting the landbird protocol used by SOPN and SODN. In doing so, we avoid duplicating effort in 

protocol development and peer review, contract administration, training, data management, analysis, 

some reporting, and project management. We also gain the ability to analyze data across broader spatial 

scales (the three networks). CHDN, SOPN, and SODN will also share protocols for Exotic Plants and 

Groundwater quantity, and CHDN will adopt SODN’s Integrated Uplands protocol. We are exploring a 

partnership with the fire program to assist in data collection and sharing. The CHDN, SODN, and SOPN 

are also working together (and with other networks) to develop protocols for Air Quality, Climate, and 

vital signs collected at seeps and springs. 
118 

Success of the CHDN also depends on partnerships outside the NPS. Table 8.6 lists some of the key 

partners for implementation of the monitoring program. Additional agreements will be put in place for 

monitoring implemented in later years. Cooperative agreements used solely for the purpose of the 

inventories are not included in this list. 

8.7 Program Review Process 

Periodic reviews of the network’s monitoring program and protocols are critical to ensure that the 

program is on the right course and determine whether course corrections are needed. Reviews should be 

accomplished in a timely fashion in order to save unnecessary expenditures of resources and time. Review 

of the program will occur at several different levels and timescales. 

1. The annual administrative report provides the TC and BOD with a summary of monitoring 

activities and accomplishments achieved during the previous fiscal year and an accounting of 

network expenditures. The work plan details the work CHDN plans to accomplish during the 

upcoming fiscal year and provides a budget allocation. Together, these documents give the TC 

and BOD an annual opportunity to review and evaluate the program’s previous-year activities and 

review plans for the upcoming year. The annual administrative report and work plan are 

presented at the annual BOD meeting, allowing the board to discuss progress and ideally resulting 

in a substantive evaluation, rather than a routine approval of the plan. 

2. The network’s annual TC meeting is an opportunity for network staff to present and discuss the 

technical aspects of the monitoring data, and for park resource managers to convene, present data 

and analyses, and discuss resource issues of concern with other managers in the network. 

3. The CHDN will undergo a “Start-up Review” by the servicewide I&M program WASO office 

within three years after the monitoring plan is accepted and implemented, and every five years 

thereafter, as described in Section 7.3.5. 

4. Network staff also will analyze and present data in other arenas on a regular basis to subject the 

network’s methodologies to ongoing peer review. 
119 

Table 8.6. Key partnerships for the Chihuahuan Desert Network, FY10–FY13. Primary agency/ Organization Division/Department Personnel Duties University of Texas at Austin Geological Sciences and Office of 

Space Research 

Dr. Gary Kocurek Roberto Guiterrez 

Collection and interpretation of development of the Dune Dyna

Rocky Mountain Bird Observatory 

 David Hanni, 

Dr. Jennifer Blakesley 

Collection and interpretation of 

New Mexico State University International and Border Programs Dr. Everett Egginton Cooperative agreement for adm

office, including rental of office use, network connections, telecoordination of logistics for wo

Sonoran Institute Cheryl McIntyre Assisting CHDN with Learning 

Southwest 

University of New Mexico Natural Heritage Program Dr. Estevan Muldavin Collection and interpretation of 

monitoring data sets from BIBE development of multiple vegetafor network parks 

State of Texas Texas Commission on 

Environmental Quality 

Dr. Bill Harrison Dr. Christine Kolbe 

Surface water quality monitorin

Texas State University Edwards Aquifer Research and 

Data Center 

Dr. Glenn Longley Stephen Porter Renee Barker Raymond Slade 

Development of Surface Watemonitoring protocols 

Sul Ross University Department of Geology and 

Chemistry 

Dr. Kevin Urbanczyk Development of Surface Wate

monitoring protocols 

121 

Chapter 9: Schedule 

This chapter describes the proposed schedule for implementing the CHDN Vital Signs Monitoring 

Program. Not all monitoring activities will begin immediately upon completion of this monitoring plan. 

The design and pilot phases of protocol development frequently require more time than final protocol 

implementation, and can last several years. Thus, development of the CHDN program is phased to 

account for both time needed for completion and realistic, balanced workloads. 

9.1 Phased Start-up Schedule for Protocol Development 

Developmental phases are required for most CHDN protocols. For some protocols, phases may simply 

entail some coordination with an entity already collecting applicable data (e.g., state and/or federal water 

quality programs). For others, implementation will require a more detailed scoping of the vital sign(s), 

pilot data collection efforts, and/or determining analysis methods for the data. In assigning a target 

calendar year for protocol completion, we have attempted to account for anticipated difficulties to project 

the most feasible completion date possible. The CHDN, where appropriate and feasible, will borrow 

existing monitoring procedures developed by other networks with arid and semi-arid lands. For some 

protocols, intensive efforts will be conducted largely in a single park, with select testing and application 

of the results from these projects expanded to other parks during or shortly after the pilot phase. In all 

cases, protocol-development projects will be based on well-established, peer-reviewed methods and 

provide relevant monitoring data for the park(s) where pilot testing is conducted. For the protocols under 

development by CHDN in the next five years, Table 9.1 shows the protocols to be completed by 

December 31 of each year. 

The general goals of the more intensive CHDN protocol-development projects are to develop sampling 

frames and classification systems, gather data needed for understanding variability in measures (e.g., 

within and across years, across sites) and its effect on statistical power, develop novel or adopt existing 

reference conditions or other thresholds, develop novel or adopt existing indices and assessment metrics, 

estimate monitoring costs, and work with parks to comply with laws, regulations, and policies and 

minimize adverse impacts of CHDN monitoring activities. Examples of protocols that require this level of 

development include Integrated Uplands monitoring and Dune Dynamics. 

Some protocols (e.g., Landbirds, Groundwater Quantity, Surface Water Quality and Dynamics) will 

require empirical, site-specific data but may not need to be as intensive as those listed above. Finally, 

protocols already developed by other programs (e.g., Air Quality, Climate) may only require minimum 

coordination to acquire data sets that will be useful in analyzing and interpreting results from other vital 

signs. 

9.2 Protocol Implementation Schedule 

Table 9.2-1 provides a schedule for development and implementation of monitoring for each CHDN vital 

sign through 2013. Not every protocol will be implemented at every park or on the same schedule. Table 

9.2-2 shows the general times of the year when field sampling for CHDN protocols is expected to occur. 

Sampling schedules include some year-round or seasonally continuous automated monitoring (air quality, 

climate, groundwater monitoring wells, river gauging stations). Most non-automated field sampling 

occurs in late spring through early fall (Table 9.2-2). 
122 

Table 9.1. Tasks to be accomplished before full monitoring is implemented. 

Protocol and 

target year for 

completion 

Vital sign(s) Key events/issues to be addressed 

Landbirds 

2010 

Bird Communities NPS-approved protocols and databases used by SOPN and SODN will 

be used. CHDN effort during 2010 will focus on sample design. 

Sampling will be conducted in CHDN parks in spring 2010. 

Invasive/Nonnative Plants 

2010 

Invasive/Nonnative Plants NPS-approved protocols and databases used by SOPN and SODN will 

be used. CHDN effort during 2010 will focus on prioritizing areas for 

sampling. Pilot testing will be conducted in CHDN parks in fall 2010. 

Integrated 

Uplands (Soils 

and Vegetation) 

2010 

Plant Community 

Composition, Soil 

Hydrologic 

Function, Biological 

Soil Crusts, Soil 

Erosion (Wind and 

Water), Bare 

Ground 

NPS-approved protocols and databases used by SODN will be used 

with slight modification (inclusion of bare ground vital sign). CHDN 

effort during 2010 will focus on sample design and exploring 

partnership with fire program for sampling. Pilot testing will be 

conducted in CHDN parks in fall 2010. 

Dune Dynamics 

2010 

Dune Formation 

and Stability, Dune 

Morphology 

Techniques for monitoring changes in dune vital signs are established. 

Utilization of LiDAR imagery has been tested. Work will focus on 

determining frequency of sampling, developing a data management 

strategy, and writing a protocol to NPS specifications. The baseline has 

been established, and sampling will not occur again until 2016. 

Groundwater 

Quantity 

2010 

Groundwater 

Quantity 

NPS-approved protocol will be adopted. Initial sampling will begin in 

late 2010 or early 2011. 

River Channel 

Morphology 

2010 

River Channel 

Characteristics 

Data collected by BIBE (or its cooperators) using peer-reviewed 

protocols will be used. CHDN focus will be on data management and 

reporting. This protocol will be applied only to the Rio Grande. 

Surface Water 

Quality and 

Dynamics 

2011 

Surface Water 

Dynamics, 

Persistence of 

Springs, Surface 

Water Quality, 

Aquatic 

Invertebrates 

The CHDN is contributing to a multi-network effort to develop peerreviewed protocols for hydrology, water quality, vegetation, and 

macroinvertebrates in seeps and springs (including spring-fed 

streams). These protocols will be used for all CHDN surface waters 

except the Rio Grande. CHDN focus will be primarily on sample design. 

Pilot testing will be conducted in spring 2011. 

Air Quality 

2011 

Ozone, Wet and 

Dry Deposition, 

Visibility and 

Particulate Matter 

Implemented through other sources. Coordinate with ARD and other 

networks (SODN, SOPN) on receipt of annual reports and data 

summaries, and reporting strategies. 

Climate 

2011 

Basic Meteorology Implemented through other sources. Coordinate with ARD and other 

networks (SODN, SOPN) on receipt of annual reports and data 

summaries, and reporting strategies. 

Landscape 

Patterns and 

Dynamics 

2012

Land Cover, LandUse Changes WASO I&M has taken the lead role on development of this protocol. 

The CHDN will coordinate with their efforts. 

For standardization, completion date is considered to be December 31 of any given year. Protocols are listed chronologically by

year of completion. 
123 

Table 9.2-1. Development (D), pilot testing (P), and implementation (I) schedule for each protocol, 

calendar years 2009–2013. 

Protocol 

2009 2010 2011 2012 2013 Frequency 

Landbirds P I I I I Annual 

Invasive/Non-native Plants D P I I I 5-year intervals 

Integrated Uplands P I I I Rotation TBD 

Dune Dynamics D D I First resample: 5 yrs post-initial; second sampling: 

5–10 yrs, etc. 

Groundwater Quantity D P I I I Periodic to continuous 

River Channel Morphology D I I I 5 year intervals 

Surface Water Quality and Dynamics D P I I Periodic to continuous 

Air Quality D I I I Continuous 

Climate D I I I Continuous 

Landscape Patterns and Dynamics1 D I I 5–10 year interval 

1

 = This protocol will be fully developed following the conclusion of the servicewide I&M program’s effort. The national office has 

taken the lead role in developing standards and useful analytical techniques. 

Table 9.2-2. General estimate of months when data collection could occur for CHDN protocols. 

Protocol 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Landbirds X X X 

Invasive/Non-native Plants1 X X X X X X 

Integrated Uplands X X X X X X X 

Dune Dynamics X X X X 

Groundwater Quantity X X X X X X X X X X X X 

River Channel Morphology X X X X X X 

Surface Water Quality and Dynamics X X X X X X X X 

Air Quality X X X X X X X X X X X X 

Climate X X X X X X X X X X X X 

Landscape Patterns and Dynamics X X X X 

Protocols are listed chronologically by year of completion. 

1

Field sampling for invasive plants will correspond to the vegetation phenology. The time frame may shift a month depending on the 

species monitored. 

9.3 Programmatic reviews 

The three-year start-up review by the WASO office is anticipated in 2013, with periodic programmatic 

reviews every five years thereafter. 

125 

Chapter 10: Budget 

This chapter presents the CHDN Vital Signs Monitoring Program budget for FY 2010, the first partial 

year of operation after review and final approval of our plan (March 2010). Table 10 shows the FY10 

network budget, including our projections for network resources devoted to information and data 

management. 

In FY10, the CHDN received $799,400 from the Servicewide I&M Vital Signs Monitoring Program, and 

$66,700 from the NPS Water Resources Division. Combined, these funding sources serve as base funds 

with which the network vital signs and water quality monitoring programs will be developed and 

implemented. We expect these amounts to remain relatively fixed, except for periodic cost of living 

adjustments for federal employees and other across-the-board rescissions. Regional assessments are 

expected to be $3,854 and $667 for I&M and NPS-WRD monies, respectively. After assessment, the 

CHDN will have a total of $861,579 (Table 10). Not shown in Table 10 is $50,000 received from the 

national Vegetation Inventory Program to conduct an accuracy assessment of the WHSA vegetation map. 

Although CHDN has received funds for vegetation mapping in the past, and expects to receive additional 

funding for vegetation maps in AMIS and BIBE, these funds do not contribute to base monitoring funds. 

Vital Signs Monitoring Program funds are held in WASO base accounts and transferred annually through 

the Intermountain Regional Office to the CHDN. All funds are managed by the CHDN program manager, 

with budget and contracting assistance from IMR staff. The BOD approves the work plan with input from 

the network program manager and TC. The work plan directs expenditure of funds to salaries, projects, 

and operations. Funds are used solely for purposes of operating the program in a way consistent with NPS 

policies, rules, and regulations. 

In FY 2010, the network will enter the Implementation Phase (FY10–FY12), defined as the period when 

the network will continue to develop and implement several protocols (e.g., Landbirds, Invasive/Nonnative Plants, Integrated Uplands), begin to implement the network’s Data Management Plan, and fund 

inventories that support protocol development. These activities will be accomplished through a 

combination of core (permanent) network staff, temporary network staff, and external cooperators (via 

CESU cooperative agreements and interagency agreements), the costs of which constitute a significant 

portion of the program budget (Table 10). Costs for current network staff are approximately 54% of the 

FY10 budget, including the one-time relocation expense for the Field Coordinator position. The 

percentage of funds allocated to network personnel will generally increase over time due to cost of living 

and step increases. The staffing plan in Chapter 8 presents one approach to achieving field data collection. 

Additional field assistance will likely be required, and the network will explore all staffing options for 

implementing protocols (CHDN temporary staff, park staff, partnerships, cooperative agreements, or 

some combination) with the CHDN BOD and TC as protocols near completion. 

In FY 2010, approximately 42% of the program budget will be allocated to external cooperators or 

contractors to provide assistance on protocol development, data management, and maintaining office 

space and support at New Mexico State University (Table 10). Through these agreements and contracts, 

we will obtain technical and statistical support as we initiate or continue protocol development. 

Operations, equipment, and travel expenses during the Implementation Phase will be allocated to 

monitoring equipment purchases, general administrative costs, and travel related to meetings, visiting 

parks, training, and protocol testing. These expense categories will increase as protocols are implemented 

(e.g., equipment costs, logistics support, field travel). 
126 

Table 10. Detailed budget for the Chihuahuan Desert Network Vital Signs Monitoring Program in 

the first year of implementation after review and approval of the monitoring plan. 

Income FY 2010 amount % of income 

Vital Signs Monitoring $794,546 92% 

Water Resources Division $66,033 8% 

Total income $861,579 

 

Expenditures 

Percentage/amount 

allocated to data 

management 

Personnel GS-level 

FY 2010 

amount ($) % Amount ($)

Program Manager (permanent) 13 107,266 10% 10,727 

Science Advisor (permanent) 13 119,167 10% 11,917 

Data Manager1 (permanent) 11 84,455 90% 76,009 

Field Coordinator (permanent) 

Relocation expenses 7/9 35,980 50,000 30% 10,794 

Biological Technician (term) 7 28,378 80% 22,701 

Biological Technician (temp) 7 23,058 50% 11,529 

Budget Analyst2

 (permanent) 9 8,780 20% 1,756 

Administrative Assistant3

 (term) 5 3,428 

I&M Writer-Editor4

 9 3,446 

subtotal $463,956 $145,432 

Cooperative agreements 

New Mexico State University (office space & support) $94,004 

Seeps/Springs, Groundwater Inventory & Protocol Development $224,440 33% 73,755 

Invasive species, uplands protocol implementation $30,000 33% 9,900 

RIGR monitoring $15,179 

subtotal $363,623 $83,655 

Operations/Equipment 

Computer equipment 4,000 

Vehicles 2,000 

Training 5,000 

General supplies and equipment $3,000 

subtotal $14,000 

Travel 

Network staff: Meetings, conferences, and training 14,000 

Park staff: Network-related meetings and conferences 6,000 

subtotal $20,000 

 Total Expenditures $861,579 27% $229,398 

1 10% of time allocated to IT duties. 

2

 Position shared with all IMR I&M networks. CHDN share is 0.12 FTE. 

3 Position shared with 4 other I&M networks. CHDN share is 0.007 FTE. 

4 1 pp, for work on monitoring plan. 
127 

Guidelines for developing a monitoring program suggest that approximately 33% of the overall budget 

should be allocated to information and data management to ensure data quality and longevity and 

facilitate communication of monitoring results. In Table 10, we provide the percent of time that each 

network position devotes to information/data management. Approximately 27% of the network budget 

will be put toward data and information management during the Implementation Phase. After the network 

fully implements monitoring, monitoring-related data management duties will be performed by core and 

term network staff, as well as temporary field staff. 

129 

Chapter 11: Literature Cited 

Abrahams, A. D., M. Neave, W. H. Schlesinger, J. Wainright, D. A. Howes, and A. J. Parsons. 2006. 

Biogeochemical fluxes across piedmont slopes of the Jornada Basin. Pages 150–175 in K. M. 

Havstad, L. F. Heunneke, and W. H. Schlesinger, eds., Structure and function of a Chihuahuan Desert 

ecosystem. New York: Oxford University Press. 

Allen, C. D., J. L. Betancourt, and T. W. Swetnam. 1998. Landscape changes in the southwestern United 

States: Techniques, long-term data sets, and trends. In T. Sisk, ed., Perspectives on the land use 

history of North America: A context for understanding our changing environment. USGS Biological 

Science Report USGS/BRD/BSR-1998-0003. 

Allmendinger, R. J. 1972. Hydrologic control over the origin of gypsum at Lake Lucero, White Sands 

National Monument, New Mexico. Thesis, New Mexico Institute of Mining and Technology, 

Socorro, New Mexico. 

Alward, R. D., J. K. Detling, and D. G. Milchunas. 1999. Grassland vegetation changes and nocturnal 

global warming. Science 283:229–231. 

Archer, S., and C. Stokes. 2000. Stress, disturbance and change in rangeland ecosystems. Pages 17–38 in

O. Arnalds and S. Archer, eds., Rangeland desertification. Dordrecht, The Netherlands: Kluwer. 

Artiola, J., I. L. Pepper, and M. L. Brusseau. 2004. Environmental monitoring and characterization. 

Burlington, Ma.: Elsevier Academic Press. 

Asner, G. P., T. R. Seastedt, and A. R. Townsend. 1997. The decoupling of terrestrial carbon and nitrogen 

cycles. BioScience 47:226–234. 

Auble, G. T., and M. L. Scott. 1998. Fluvial disturbance patches and cottonwood recruitment along the 

upper Missouri River, Montana. Wetlands 18:546–556. 

Ayala, R., T. L. Griswold, and S. H. Bullock. 1993. The native bees of Mexico. Pages 179–228 in T. P. 

Ramamoorthy, R. Bye, A. Lot, and J. Fa, eds., Biological diversity of Mexico. New York: Oxford 

University Press. 

Badgley, C., and D. L. Fox. 2000. Ecological biogeography of North American mammals: Species 

density and ecological structure in relation to environmental gradients. Journal of Biogeography 

27:1437–1467. 

Bailey, R. G., P. E. Avers, T. King, and W. H. McNab, eds. 1994. Ecoregions and subregions of the 

United States, map of scale 1:7,500,000. US Geological Survey, Washington, D.C. 

Baker, M. B., Jr., P. F. Ffolliott, L. F. DeBano, D. G. Neary. 2004. Riparian areas of the southwestern 

United States: Hydrology, ecology, and management. Boca Raton, Fl.: Lewis Publishers. 

Barbour, M. T., J. Gerritsen, B. D. Snyder, and J. B. Stribling. 1999. Rapid bioassessment protocols for 

use in wadeable streams and rivers: Periphyton, benthic macroinvertebrates and fish. Second edition. 

EPA 841-B-99-002. US Environmental Protection Agency, Washington, D.C. 

Barrett, G. W., G. M. Van Dyne, and E. P. Odum. 1976. Stress ecology. BioScience 26:192–194. 

Basabilvazo, G. T., R. G. Myers, and E. L. Nickerson. 1994. Geohydrology of the high energy laser 

system test facility site, White Sands Missile Range, Tularosa Basin, south-central New Mexico. U.S. 

Geological Survey, Reston, Virginia. 
130 

Bawden, G. W., M. Sneed, S. V. Stork, and D. L. Galloway. 2003. Measuring human-induced land 

subsidence from space. USGS Fact Sheet 069-03. U.S. Geological Survey, Denver, Colorado. 

Becker, J. C., and A. W. Groeger. 2010. Distribution of mercury in the sediments of Amistad 

International Reservoir, Texas, USA. Proceedings of the International Association of Theoretical and 

Applied Limnology 30. 

Belnap, J. 2001. Biological soil crusts: Webs of life in the desert. USGS Fact Sheet FS-065-01. U.S. 

Geological Survey, Denver, Colorado. 

——. 2003. Biological soil crusts and wind erosion. Pages 339–347 in J. Belnap and O. L. Lange, eds., 

Ecological Studies Series 150, Biological soil crusts: Structure, function, and management. Berlin, 

Germany: Springer-Verlag. 

Belnap, J., and O. L. Lange, eds. 2001. Biological soil crusts: Structure, function, and management. 

Berlin, Germany: Springer-Verlag. 

Bender, S., S. Shelton, K. Conrad Bender, and A. Kalmbach, eds. 2005. Texas comprehensive wildlife 

conservation strategy 2005–2010. Texas Parks and Wildlife Department, Austin, Texas. 

Benson, S. B. 1932. Three new rodents from lava beds of southern New Mexico. University of California 

Publications in Zoology 38:335–344. 

Bestelmeyer, B. T., J. R. Brown, K. M. Havstad, G. Chavez, and R. Alexander, and J. E. Herrick. 2003. 

Development and use of state-and-transition models for rangelands. Journal of Range Management 

56: 114–126. 

Blair, W. F. 1941. Annotated list of mammals of the Tularosa Basin, New Mexico. American Midland 

Naturalist 26:218–229. 

Breshears, D. D., J. J. Whicker, M. P. Johansen, and J. E. Pinder, III. 2003. Wind and water erosion and 

transport in semi-arid shrubland, grassland and forest ecosystems: Quantifying dominance of 

horizontal wind-driven transport. Earth Surface Processes and Landforms 28:1189–1209. 

Britten, M. E., E. W. Schweiger, B. Frakes, D. Manier, and D. Pillmore. 2007. Rocky Mountain Network 

vital signs monitoring plan. Natural Resource Report NPS/ROMN/NRR—2007/010. National Park 

Service, Fort Collins, Colorado. 

Brown, J. H., and E. J. Heske. 1990. Control of a desert-grassland transition by a keystone rodent guild. 

Science 250:1705–1707. 

Bryan, K. B., and J. P. Karges. 2001. Recent bird records in the Davis Mountains. Texas Birds 3:40–53. 

Bryce, S. A., R. M. Hughes, and P. R. Kaufmann. 2002. Development of a bird integrity index: Using 

bird assemblages as indicators of riparian condition. Environmental Management 30:294–310. 

Buckland, S. T., D. R. Anderson, K. P. Burnham, J. L. Laake, D. L. Borchers and L. Thomas. 2001. 

Introduction to distance sampling: Estimating abundance of biological populations. Oxford, U.K.: 

Oxford University Press. 

Buckland, S. T., D. R. Anderson, K. P. Burnham, J. L. Laake, D. L. Borchers and L. Thomas, eds. 2004. 

Advanced distance sampling: Estimating abundance of biological populations. Oxford, U.K.: Oxford 

University Press. 

Camp, A., H. M. Poulos, R. Gatewood, J. Sirotnak, and J. Karges. 2006. Assessment of top down and 

bottom up controls on fire regimes and vegetation abundance and distribution patterns in the 

Chihuahuan Desert borderlands: A hierarchical approach. Final report to the Joint Fire Science 

Program, Project #03-3-3-13. 
131 

Carmen, J. G., and J. D. Brotherson. 1982. Comparison of sites infested and not infested with saltcedar 

(Tamarix ramosissima) and Russian olive (Elaeagnus augustifolia). Weed Science 30:360–364. 

Chapin, F. S., III, M. S. Torn, and M. Tateno. 1996. Principles of ecosystem sustainability. American 

Naturalist 148:1016–1037. 

Chapin, F. S., III, B. H. Walker, R. J. Hobbs, D. U. Hooper, J. H. Lawton, O. E. Sala, and D. Tilman. 

1997. Biotic control over the functioning of ecosystems. Science 277:500–504. 

Chew, R. M. 1974. Consumers as regulators of ecosystems: an alternative to energetics. Ohio Journal of 

Science 74:359–370. 

Christensen, K. M., and T. G. Whitham. 1993. Impact of insect herbivores on competition between birds 

and mammals for pinyon pine seeds. Ecology 74:2270–2278. 

Chung-MacCoubrey, A. L., R. E. Truitt, C. C. Caudill, T. J. Rodhouse, K. M. Irvine, J. R. Siderius, and 

V. K. Chang. 2008. Mojave Desert Network vital signs monitoring plan. NPS/MOJN/NRR—

2008/057. National Park Service, Fort Collins, Colorado. 

Cochran, W. G. 1977. Sampling techniques. Third edition. New York: John Wiley and Sons. 

Cole, D. R., and H. C. Monger. 1994. Influence of atmospheric CO2 on the decline of C4 plants during 

the last deglaciation. Nature 368:533–536. 

Collyer, M. L., J. M. Novak, and C. A. Stockwell. 2005. Morphological divergence of native and recently 

established populations of White Sands Pupfish (Cyprinodon tularosa). Copeia 2005:1–11. 

Comstock, J. P., and J. R. Ehleringer. 1992. Plant adaptation in the Great Basin and Colorado Plateau. 

The Great Basin Naturalist 52:195–215. 

Costanza, R., R. Arge, R. de-Groot, S. Farber, M. Grasso, B. Hannon, K. Limburg, S. Naeem, R. Oneil, J. 

Paruelo, R. Raskin, P. Sutton, and J. van denBelt. 1998. The value of ecosystem services: Putting the 

issues in perspective. Ecological Economics 25:67–72. 

Crabaugh, M. M. 1994. Controls on accumulation in modern and ancient wet eolian systems. 

Dissertation, University of Texas, Austin, Texas. 

Cruz, R. R. 1985. Annual water-resources review, White Sands Missile Range, New Mexico, 1984. U.S. 

Geological Survey, Reston, Virginia. 

D’Antonio, C. M., and P. M. Vitousek. 1992. Biological invasions by exotic grasses: The grass/fire cycle, 

and global change. Annual Review of Ecology and Systematics 23:63–87. 

Dahm, C. N., R. J. Edwards, and F. P. Gelwick. 2005. Gulf Coast rivers of the southwestern United 

States. Pages 181–228 in A. C. Benke and C. E. Cushing, eds., Rivers of North America. Burlington, 

Ma.: Elsevier Academic Press. 

Davenport, D. C., P. E. Martin, and R. M. Hagar. 1982. Evapotranspiration from riparian vegetation: 

Water relations and irrecoverable losses for saltcedar. Journal of Soil and Water Conservation 

37:362–364. 

Dick-Peddie, W. A. 1993. New Mexico Vegetation: Past, present, and future. Albuquerque: University of 

New Mexico Press. 

Dinerstein E., D. Olson, J. Atchley, C. Loucks, S. Contreras-Balderas, R. Abell, E. Indigo, E. Enkerlin, C. 

E. William, and G. Castelleja. 2000. Ecoregion-based conservation in the Chihuahuan Desert: A 

biological assessment. World Wildlife Fund, Washington, D.C. 

http://www.worldwildlife.org/what/wherewework/chihuahuandesert/WWFBinaryitem2757.pdf. Last 

accessed March 15, 2009. 
132 

Drewa P. B., and K. M. Havstad. 2001. Effects of fire, grazing, and the presence of shrubs on Chihuahuan 

desert grasslands. Journal of Arid Environments 48:429–443. 

Edwards, D. 1998. Issues and themes for natural resource trends and change detection. Ecological 

Application 8:323–325. 

Ehleringer, J. R., S. Schwinning, and R. Gebauer. 2000. Water use in arid land ecosystems. Pages 347–

365 in M. C. Press, J. D. Scholes, and M. G. Barker, eds., Physiological plant ecology: Proceedings of 

the 39th Symposium of the British Ecological Society, 7–9 September 1998, University of York. 

Boston: Blackwell Science. 

Elzinga, C. L., D. W. Salzer, and J. W. Willoughby. 1998. Measuring and monitoring plant populations. 

Bureau of Land Management Technical Reference 1730-1. Bureau of Land Management, 

Washington, D.C. 

Environment Canada. 2007. Glossary of biological monitoring terms. http://www.ec.gc.ca/inrpnpri/default.asp?lang=En&n=9264E929-1. Last accessed February 16, 2010. 

Fancy, S. G., J. E. Gross, and S. L. Carter. 2009. Monitoring the condition of natural resources in U.S. 

national parks. Environmental Monitoring and Assessment 151:161–174. 

Fenn, M. E., J. S. Baron, E. B. Allen, H. M. Rueth, K. R. Nydick, et al. 2003. Ecological effects of 

nitrogen deposition in the western United States. BioScience 53(4):404–420. 

Ffolliott, P. F., C. M. Jones, and W. D. Jones. 2004. Chapter 8: Mammals, avifauna, and herptofauna. 

Pages 169–192 in M. B. Baker, Jr., P. F. Ffolliott, L. F. DeBano, and D. G. Neary, eds., Riparian 

areas of the southwestern United States: Hydrology, ecology, and management. Boca Raton, Fl.: 

Lewis Publishers. 

 Fields, M. J., D. P. Coffin, and J. R. Gosz. 1999. Burrowing activities of kangaroo rats and patterns in 

plant species dominance at a shortgrass steppe-desert grassland ecotone. Journal of Vegetation 

Science 10:123–130. 

Frank, A. J. 1994. Models for airflow velocity profiles in natural settings: Accounting for atmospheric 

conditions and secondary flow over eolian dunes. Dissertation, University of Texas at Austin. 

Frank, A. J., and G. Kocurek. 1994. Effects of atmospheric conditions on wind profiles and aeolian sand 

transport with an example from White Sands National Monument. Earth Surface Processes and 

Landforms 19:735–746. 

——. 1996. Airflow up the stoss slope of sand dunes: Limitations of current understanding. Pages 47–54 

in N. Lancaster, ed., Response of aeolian processes to global change. Amsterdam: Elsevier Academic 

Press. 

Fredrickson, E. L., R. E. Estell, A. Laliberte, and D. M. Anderson. 2006. Mesquite recruitment in the 

Chihuahuan Desert: Historic and prehistoric patterns with long-term impacts. Journal of Arid 

Environments 65:285–295. 

Fryberger, S. G. 1979. Dune forms and wind regime. Chapter F in E. D. McKee, ed., A study of global 

sand seas. USGS Professional Paper 1052:137–169. 

——. 2003. Geology of White Sands National Monument. 

http://www2.nature.nps.gov/geology/parks/whsa. Last accessed February 16, 2010. 

Galloway, J. N., J. D. Aber, J. W. Erisman, S. P. Seitzinger, R. W. Howarth, E. B. Cowling, and B. J. 

Cosby. 2003. The nitrogen cascade. BioScience 53:341–356. 

Geissler, P. H., and T. L. McDonald. 2003. A comparison of grid sampling designs with stratified/nonuniform probability sampling designs for national park monitoring (summary). Page 367 in D. 
133 

Harmon, B. M. Kilgore, and G. E. Vietzke, eds., Proceedings of the 2003 George Wright 

Society/National Park Service Joint Conference. The George Wright Society, Hancock, Michigan. 

Gillette, D. A., and A. M. Pitchford. 2004. Sand flux in the northern Chihuahuan desert, New Mexico, 

USA, and the influence of mesquite-dominated landscapes. Journal of Geophysical Research-Earth 

Surface 109:3. 

Grimm, V. and C. Wissel. 1997. Babel or the ecological stability discussions: An inventory and analysis 

of terminology and a guide for avoiding confusion. Oecologia 109:323–334. 

Groeger, A. W., R. H. Kamps, M. D. Funk, D. Woodward, A. Thompson, J. R. Branom, and M. Cave. In 

press. Mixing of the desert rivers: Limnology of the International Amistad Reservoir. Proceedings of 

the 6th Symposium on the Natural Resources of the Chihuahuan Desert. 

Groeger, A. W., and J. J. Gustafson. 1994. Chemical composition and variability of the waters of the 

Edwards Plateau, central Texas. Pages 39–46 in J. A. Stanford and H. M. Valett, eds., Proceedings of 

the Second International Conference on Ground Water Ecology. American Water Resources 

Association, Herndon, Virginia. 

Gutiérrez, M. E., and E. Johnson. In press. Salinity trend in the lower Rio Conchos, Chihuahua. 

Proceedings of the 6th Symposium on the Natural Resources of the Chihuahuan Desert. Chihuahuan 

Desert Research Institute, Alpine, Texas. 

Gutiérrez, M., E. Johnson, and K. Mickus. 2004. Watershed assessment along a segment of the Rio 

Conchos in northern Mexico using satellite images. Journal of Arid Environments 56:395–412. 

Guo, Q. F. 1998. Microhabitat differentiation in Chihuahuan Desert plant communities. Plant Ecology 

139:71–80. 

Guo, Q. F., D. B. Thompson, T. J. Valone, and J. H. Brown. 1995. The effects of vertebrate granivores 

and folivores on plant community structure in the Chihuahuan Desert. Oikos 73:251–259. 

Gutzwiller, K. J., and W. C. Barrow. 2002. Does bird community structure vary with landscape 

patchiness? A Chihuahuan Desert perspective. Oikos 98:284–298. 

Hager, S. B. 2002. Quantification of body color for the lesser earless lizard, Holbrookia maculata: 

Evidence for interpopulational differences. Southwest Naturalist 47:299–307. 

Hart, C. R. 2004. The Pecos River ecosystem project report. Texas Cooperative Extension, The Texas 

A&M University System. 

Hendrickson, D. A., J. C. Marks, A. Moline, E. Dinger, and A. Cohen. 2008. Combining ecological 

research and conservation: A case study in Cuatro Ciénegas, Coahuila, México. In L. Stevens and V. 

Meretsky, eds., Aridland springs in North America: Ecology and conservation. Tucson: University of 

Arizona Press. 

Hereford, R., R. H. Webb, and C. I. Longpre. 2004. Precipitation history of the Mojave Desert region, 

1893–2001. USGS Fact Sheet 117-03. Denver, Co.: U.S. Geological Survey. 

http://pubs.usgs.gov/fs/fs117-03/. Last accessed February 17, 2010. 

Hernández, H. M., and R. T. Bárcenas. 1995. Endangered cacti in the Chihuahuan Desert: I. Distribution 

patterns. Conservation Biology 9:1176–1188. 

Herrick, J. E., W. G. Whitford, A. G. de Soyza, and J. W. Van Zee. 1996. Soil and vegetation indicators 

for assessment of rangeland ecological condition. Pages 157–166 in A. G. Celedonio, ed., North 

American workshop on monitoring for ecological assessment of terrestrial and aquatic ecosystems. 

USDA Forest Service General Technical Report RM-GTR-284. 
134 

Holling, C. S., L. H. Gunderson, and D. Ludwig. 2002. In quest of a theory of adaptive change. Pages 3–

22 in L. H. Gunderson and C. S. Holling, eds., Panarchy: Understanding transformations in human 

and natural systems. Washington, D.C.: Island Press. 

Housman, D. C., E. Naumburg, T. E. Huxman, T. N. Charlet, R. S. Nowak, and S. D. Smith. 2006. 

Increases in desert shrub productivity under elevated carbon dioxide vary with water availability. 

Ecosystems 9:374–385. 

Hubbs, C., R. J. Edwards, and G. P. Garrett. 2002. Threatened fishes of the world: Gambusia gaigei

Hubbs, 1929 (Poeciliidae). Environmental Biology of Fishes 65:82. 

Huenneke, L. F., and W. H. Schlesinger. 2006. Patterns of net primary production in Chihuahuan Desert 

ecosystems. Pages 232–246 in K. M. Havstad, L. F. Heunneke, and W. H. Schlesinger, eds., Structure 

and function of a Chihuahuan Desert ecosystem. New York: Oxford University Press. 

Huff, G. F., J. T. Richie, and M. H. Reiser. 2006. Chihuahuan Desert Network water resource information 

and assessment report, Phase II. National Park Service, Chihuahuan Desert Network, Las Cruces, 

New Mexico. 

Jackson, J. A., ed. 1997. Glossary of geology. Fourth edition. Alexandria, Va.: American Geological 

Institute. 

Jackson, R. D., J. W. Bartolome, and B. H. Allen-Diaz. 2002. State and transition models: Response to an 

ESA symposium. Bulletin of the Ecological Society of America 83:194–196. 

Jenkins, K., A. Woodward, and E. Schreiner. 2002. A framework for long-term ecological monitoring in 

Olympic National Park: Prototype for the coniferous forest biome. USGS Forest and Rangeland 

Ecosystem Science Center, Olympic Field Station, Port Angeles, Washington. 

Jenny, H. 1941. Factors of soil formation: A system of quantitative pedology. New York: McGraw-Hill. 

——. 1980. The soil resource: Origin and behavior. New York: Springer-Verlag. 

Johansen, J. R. 1993. Cryptogamic crusts of semiarid and arid lands of North America. Journal of 

Phycology 29:140–147. 

Johnson, M. C. 1974. Brief resume of botanical, including vegetation features, of the Chihuahuan Desert 

region with special emphasis on their uniqueness. Pages 335–362 in R. H. Wauer and D. H. Riskind, 

eds., Transactions of the symposium of the biological resources of the Chihuahuan Desert region, 

United States and Mexico. National Park Service Transactions and Proceedings Series No. 3. 

Washington, D.C.: U.S. Government Printing Office. 

Jorgensen, E. E., S. Demarais, and T. Monasmith. 2000. Rodent habitats in a Chihuahuan Desert/desert 

plains grassland ecotone. Texas Journal of Science 52:303–312. 

Jorgensen, S. E. 1986. Fundamentals of ecological modeling. New York: Elsevier Academic Press. 

Karlen, D. L., M. J. Mausback, J. W. Doran, R. G. Cline, R. F. Harris, and G. E. Schuman. 1997. Soil 

quality: A concept, definition, and framework for evaluation. Soil Science Society of America Journal 

61:4–10. 

Karr, J. R., K. D. Fausch, P. L. Angermeier, P. R. Yant, and L. J. Schlosser. 1986. Assessing biological 

integrity in running waters a method and its rationale. Special Publication 5. Illinois Natural History 

Survey, Champaign, Illinois. 

Kelly, M. E. 2001. The Río Conchos: A preliminary overview. Texas Center for Policy Studies, Austin, 

Texas. 

Kerley, G. I. H., W. G. Whitford, and F. R. Kay. 1997. Mechanisms for the keystone status of kangaroo 

rats: Gramnivory rather than granivory? Oecologia 111:422–428. 
135 

Kidron, G. J., and H. C. O. Monger. 1999. Microbiotic crusts as indicators of surface moisture and 

erosion. Abstract from Annual Meeting of Soil Science Society of America, Salt Lake City, Utah, 

1999. 

Kidron, G. J., and H. C. Monger. 2001. The impact of microbiotic crust on runoff yield from three parent 

materials from the Negev and the Chihuahuan deserts: Climatic, paleoclimatic and geomorphological 

implications. Page 70 in Z. Gvirtzman and R. Amit, eds.,Annual Meeting of the Israel Geological 

Society, 2001. 

Kiver, E. P., and D. V. Harris. 1999. Geology of U.S. parklands. New York: John Wiley and Sons. 

Kocurek, G. 2008. LiDAR surveys of gypsum dune fields in White Sands National Monument, New 

Mexico. Unpublished annual report for FY07, National Park Service, Chihuahuan Desert Network, 

Las Cruces, New Mexico. 

Kocurek, G. M. 2007. LIDAR surveys of gypsum dune fields in White Sands National Monument, New 

Mexico: Pilot study for assessing dune dynamics. Unpublished technical report to National Park 

Service, Chihuahuan Desert Network, Las Cruces, New Mexico. 

Kocurek, G., M. Carr, R. Ewing, K. G. Halvholm, Y. C. Nagar, and A. K. Singvi. 2007. White Sands 

dune field, New Mexico: Age dune dynamics and recent accumulations. Sedimentary Geology 

197:313–331. 

Krogh, S. N., M. S. Zeisset, E. Jackson, and W. G. Whitford. 2002. Presence/absence of a keystone 

species as an indicator of rangeland health. Journal of Arid Environments 50:513–519. 

Landres, P. B., P. Morgan, and F. J. Swanson. 1999. Overview of the use of natural variability concepts in 

managing ecological systems. Ecological Applications 4:1179–1188. 

Langford, R. P. 2003. The Holocene history of the White Sands dune field and influences on eolian 

deflation and playa lakes. Quaternary International 104:31–39. 

Langford, R. P., J. M. Rose, D. E. White. 2009. Groundwater salinity as a control on development of 

eolian landscape: An example from the White Sands of New Mexico. Geomorphology 105:39-49. 

Legendre, P. 2008. Studying beta diversity: Ecological variation partitioning by multiple regression and 

canonical analysis. Journal of Plant Ecology 1(1):3–8. 

Lessler, J. T., and W.D. Kalsbeek. 1992. Nonsampling errors in surveys. New York: John Wiley and 

Sons. 

Likens, G. 1992. An ecosystem approach: Its use and abuse. Excellence in ecology, book 3. 

Oldendorf/Luhe, Germany: Ecology Institute. 

Lohr, S. L. 1999. Sampling: Design and analysis. Pacific Grove, Ca.: Duxbury Press. 

MacCluskie, M., and K. L. Oakley. 2005. Central Alaska Network: Vital signs monitoring plan. National 

Park Service, Fort Collins, Colorado. 

Mack, M. N., and C. M. D’Antonio. 1998. Impacts of biological invasions on disturbance regimes. 

Trends in Ecology and Evolution 13:195–198. 

MacMahon, J. 2000. Warm deserts. Chapter 8 in M. G. Barbour and W. D. Billings, eds., North American 

terrestrial vegetation. Second edition. Cambridge, U.K.: Cambridge University Press. 

MacMahon, J. A., and F. H. Wagner. 1985. 12A: The Mojave, Sonoran, and Chihuahuan deserts of North 

America. Pages 105–202 in M. Evenari, I. Noy-Meir, and D. W. Goodall, eds., Hot deserts and arid 

shrublands. Amsterdam: Elsevier Academic Press. 
136 

Malm,W. C. 1999. Introduction to visibility. National Park Service and Colorado State Institute for 

Research on the Atmosphere, Fort Collins, Colorado. 

Maniero, T. 2001. Guidance on air quality and air quality related values: Vital signs monitoring in 

national parks. Unpublished report. National Park Service-Air Resources Division, Denver, Colorado. 

Manly, B. F. J. 2001. Statistics for environmental science and management. New York: Chapman and 

Hall/CRC Press. 

Marcot, B. 1996. An ecosystem context for bat management: A case study of the interior Columbia River 

Basin, USA. Pages 19–38 in R. M. R. Barclay and R. M. Brigham, eds. Bats and Forests Symposium. 

British Columbia Ministry of Forestry, Victoria, British Columbia, Canada. 

Margoluis, R., and N. Salafsky. 1998. Measures of success: Designing, managing, and monitoring 

conservation and development projects. Washington, D.C.: Island Press. 

Marsh, H., and D. F. Sinclair. 1989. Correcting for bias in strip transect aerial surveys of aquatic fauna. 

Journal of Wildlife Management 53:1017–1024. 

McAuliffe, J. R. 2003. The interface between precipitation and vegetation: The importance of soils in arid 

and semiarid environments. Pages 9–27 in J. F. Weltzin, and G. R. McPherson, eds., Changing 

precipitation regimes and terrestrial ecosystems. Tucson: University of Arizona Press. 

McBean, E. A., and F. A. Rovers. 1998. Statistical procedures for analysis of environmental monitoring 

data and risk assessment. PTR Environmental Management and Engineering Series, volume 3. 

Indianapolis: Prentice Hall PTR . 

McDonald, T. L. 2003. Review of environmental monitoring methods: Survey designs. Environmental 

Monitoring and Assessment 85:277–292. 

McDonald, T. L., and P. H. Geissler. 2004. Systematic and stratified sampling designs in long-term 

ecological monitoring studies. Unpublished report. 

McLean, J. S. 1970. Saline ground-water resources of the Tularosa basin, New Mexico, Report No. 561. 

U.S. Office of Saline Water Research and Development, Progress Report, volume 571. 

——. 1975. Saline ground water in the Tularosa Basin, New Mexico. Pages 237–238 in New Mexico 

Geological Society Guidebook No. 26: Las Cruces country. 

McPherson, G. R. 1995. The role of fire in the desert grasslands. Pages 130–151 in M. P. McClaran and 

T. R. van Devender, eds., The desert grassland. Tucson: University of Arizona Press. 

Menke, S. B. 2003. Lizard community structure across a grassland-creosote bush ecotone in the 

Chihuahuan Desert. Canadian Journal of Zoology 81:1829–1838. 

Merola-Zwartjes, M. 2005. Birds of southwestern grasslands: Status, conservation, and management. 

Pages 71–139 in D. M. Finch, ed., Assessment of grassland ecosystem conditions in the southwestern 

United States: Wildlife and fish, volume 2. USDA Forest Service General Technical Report RMRSGTR-135, volume 2. 

Michener, W. K., T. J. Baerwald, P. Firth, M. A. Palmer, J. L. Rosenberger, E. A. Sandlin, and H. 

Zimmerman. 2001. Defining and unraveling biocomplexity. BioScience 51:1018–1023. 

Michener, W. K., J. W. Brunt, J . J. Helly, T. B. Kirchner, and S. G. Stafford. 1997. Nongeospatial 

metadata for the ecological sciences. Ecological Applications 7:330–342. 

Miller, M. E. 2005. The structure and functioning of dryland ecosystems: Conceptual models to inform 

long-term ecological monitoring. USGS Scientific Investigations Report 2005-5197. 
137 

Miller, R. R. 1974. Composition and derivation of the native fish fauna of the Chihuahuan Desert region. 

Pages 365–381 in R. H. Wauer and D. H. Riskind, eds., Transactions of the Symposium on the 

Biological Resources of the Chihuahuan Desert Region, United States and Mexico, Sul Ross State 

University, Alpine Texas, October 17–18, 1974. National Park Service Transactions and Proceedings 

Series, Number 3. 

Mills, G. S., J. B. Dunning, and J. M. Bates. 1991. The relationship between breeding bird density and 

vegetation volume. Wilson Bulletin 103:468–479. 

Milly, P. C. D., K. A. Dunne, and A. V. Vecchia. 2005. Global pattern of trends in streamflow and water 

availability in a changing climate. Nature 438:347–350. 

Minckley, W. L. 1974. Endemic fishes of the Cuatro Cienegas basin, northern Coahuila, Mexico. Pages 

383–403 in R. H. Wauer and D. H. Riskind, eds., Transactions of the Symposium on the Biological 

Resources of the Chihuahuan Desert Region, United States and Mexico, Sul Ross State University, 

Alpine Texas, October 17–18, 1974. National Park Service Transactions and Proceedings Series, 

Number 3. 

Monger, H. C, B. A. Nolen, A. Laliberte, J. J. Martinez-Rios, and A. Granados-Olivas. 2005. Landforms 

of the Chihuahuan Desert. 15th Annual Jornada Symposium, July 14, 2005. New Mexico State 

University, Las Cruces, New Mexico. 

Monger, H. C., and B. T. Bestelmeyer. 2006. The soil-geomorphic template and biotic change in arid and 

semi-arid ecosystems. Journal of Arid Environments 65:207–218. 

Myers, R. G. 1983. Test wells T21, T22, and T25, White Sands Missile Range, Dona Ana County, New 

Mexico. U.S. Geological Survey, Reston, Virginia. 

Myers, R. G., and K. M. Pinckley. 1987. Test wells TW1, TW2, and TW3, White Sands Missile Range, 

Otero County, New Mexico. U.S. Geological Survey, Reston, Virginia. 

Myers, R. G., and S. C. Sharp. 1989. Biannual water-resources review, White Sands Missile Range, New 

Mexico, 1986 and 1987. U.S. Geological Survey, Reston, Virginia. 

——. 1992. Annual water-resources review, White Sands Missile Range, New Mexico, 1988. U.S. 

Geological Survey, Reston, Virginia. 

Naiman J., H. Décamps, and M. Pollock. 1993. The role of riparian corridors in maintaining regional 

biodiversity. Ecological Applications 3:209–212. 

Naranjo, L. G., and R. J. Raitt. 1993. Breeding bird distribution in Chihuahuan Desert habitats. 

Southwestern Naturalist 38:43–51. 

Nash, M. H., and W. G. Whitford. 1995. Subterranean termites–regulators of soil organic-matter in the 

Chihuahuan Desert. Biology and Fertility of Soils 19:15–18. 

National Park Service (NPS). 1999. Natural resource challenge: The National Park Service’s action plan 

for preserving natural resources. National Park Service, Washington, D.C. 

——. 2001. NPS management policies. National Park Service, Denver Service Center, Denver, Colorado. 

——. 2006a. Recommended approach for developing a network monitoring program. 

http://science.nature.nps.gov/im/monitor/approach.cfm. Last accessed February 17, 2010. 

——. 2006b. Monitoring planning & design: The 3-phase approach. 

http://science.nature.nps.gov/im/monitor/3-PhaseApproach.cfm. Last accessed February 17, 2010. 

National Park Service, Air Resources Division (NPS-ARD). 2002. Air quality in the national parks. 

Second edition. National Park Service-Air Resources Division, Lakewood, Colorado. 
138 

——. 2004. Assessing the risk of foliar injury from ozone on vegetation in parks in the Chihuahuan 

Desert Network. National Park Service-Air Resources Division, Fort Collins, Colorado. 

Neilson, R. P. 1986. High resolution climatic analysis and southwest biogeography. Science 232:27–34. 

Neusser, S. M., F. J. Breidt, and W. A. Fuller. 1998. Design and estimation for investigating the dynamics 

of natural resources. Ecological Application 8:234–245. 

New Mexico Department of Game and Fish (NMGF). 2005. Comprehensive wildlife conservation 

strategy for New Mexico. New Mexico Department of Game and Fish, Santa Fe, New Mexico. 

Noon, B. R. 2003. Conceptual issues in monitoring ecological systems. Pages 27–71 in D. E. Busch and J. 

C. Trexler, eds., Monitoring ecosystems: Interdisciplinary approaches for evaluating ecoregional 

initiatives. Washington, D.C.: Island Press. 

Northington, D. K., and T. L. Burgess. 1979. Status of rare and endangered plant species of the 

Guadalupe Mountains National Park, Texas. Pages 59–77 in H. H. Genoways and R. L. Baker, eds., 

Biological investigations in the Guadalupe Mountains National Park, Texas. National Park Service 

Proceedings and Transactions Series Number Four. 

Noy-Meir, I. 1973. Desert ecosystems: Environment and producers. Annual Review of Ecology and 

Systematics 4:25–51. 

O’Dell, T. E., S. L. Garman, A. Evenden, M. Beer, E. Nance, A. Wight, M. A. Powell, D. Perry, R. 

DenBleyker, S. Daw and others. 2005. Northern Colorado Plateau Inventory and Monitoring Network 

vital signs monitoring plan. National Park Service, Northern Colorado Plateau Network, Moab, Utah. 

Oakley, K. L., L. P. Thomas, and S. G. Fancy. 2003. Guidelines for long-term monitoring protocols. 

Wildlife Society Bulletin 31:1000–1003. 

Okin, G. S., D. A. Gillette, and J. E. Herrick. 2006. Multi-scale controls on and consequences of Aeolian 

processes in landscape change in arid and semi-arid environments. Journal of Arid Environments 

65:253–275. 

Olson, D. M., and E. Dinerstein. 1998. The global 200: A representation approach to conserving the 

earth’s most biologically valuable ecoregions. Conservation Biology 3:502–512. 

Onorato, D. P., E. C. Hellgren, R. A. Van Den Bussche, and D. L. Doan-Crider. 2004. Phylogeographic 

patterns within a metapopulation of black bears (Ursus americanus) in the American Southwest. 

Journal of Mammalogy 85:140–147. 

Patrick, G. R. 1980. Plant succession in the gypsum dune field of White Sands National Monument. 

Thesis, University of Texas, El Paso, Texas. 

Patrick, G. R., and W. H. Reid. 1980. Plant succession in the parabolic interdunes at White Sands 

National Monument, abstract. Journal of Arizona-Nevada Academy of Sciences, Proceedings 

Supplement 15:12–13. 

Pellant, M., P. Shaver, D. A. Pyke, and J. E. Herrick. 2000. Interpreting indicators of rangeland health, 

version 3. Technical Reference 1734-6. Bureau of Land Management, National Science and 

Technology Center, Denver, Colorado. 

Peters, D. P. C., and K. M. Havstad. 2006. Nonlinear dynamics in arid and semi-arid systems: Interactions 

among drivers and processes across scales. Journal of Arid Environments 65:196–206. 

Peters, D. P. C., and R. P. Gibbens. 2006. Plant communities in the Jornada Basin: The dynamic 

landscape. Pages 211–231 in K. M. Havstad, L. F. Heunneke, and W. H. Schlesinger, eds., Structure 

and function of a Chihuahuan Desert ecosystem. New York: Oxford University Press. 
139 

Peters, D. P. C., B. T. Bestelmeyer, J. E. Herrick, E. L. Frederickson, H. C. Monger, and K. M. Havstad. 

2006. Disentangling complex landscapes: New insights into arid and semiarid system dynamics. 

BioScience 56:491–501. 

Pittenger, J. S., and C. L. Springer. 1999. Native range and conservation of the White Sands pupfish 

(Cyprinodon tularosa). Southwestern Naturalist 44:157–165. 

Pollock, K. H. 2000. Capture-recapture models. Journal of the American Statistical Association 95:293–

296. 

Pollock, K. H., H. Marsh, L. L. Bailey, G. L. Farnsworth, T. R. Simons, and M. W. Alldredge. 2004. 

Separating components of detection probability in abundance estimation: An overview with diverse 

examples. Pages 43–58 in W. L. Thompson, ed., Sampling rare or elusive species: Concepts, designs, 

and techniques for estimating population parameters. Washington, D.C.: Island Press. 

Porter, S. D., R. A. Barker, R. M. Slade, Jr., and G. Longley. 2009. Historical perspective of surface water 

and groundwater resources in the Chihuahuan Desert Network, National Park Service. Edwards 

Aquifer Research & Data Center Report R1-09, Texas State University, San Marcos, Texas. 

Powell, A. M., and B. L. Turner. 1977. Aspects of the plant biology of the gypsum outcrops of the 

Chihuahuan Desert. Pages 315–325 in R. H. Wauer and D. H. Risking, eds., Transactions of the 

Symposium of the Biological Resources of the Chihuahuan Desert Region, United States and Mexico. 

National Park Service Transactions and Proceedings Series Three. 

Prichard, D., J. Anderson, C. Correll, J. Fogg, K. Gebhardt, R. Krapf, S. Leonard, B. Mitchell, and J. 

Staats. 1998. Riparian area management: A user guide to assessing proper functioning condition and 

the supporting science for lotic areas. Technical Reference 1737-15, BLM/RS/ST-98/001-1737. 

Bureau of Land Management, Denver, Colorado. 

Pronatura Noreste, The Nature Conservancy, and World Wildlife Fund. 2004. Ecoregional conservation 

assessment of the Chihuahuan Desert. World Wildlife Fund, Washington, D.C. 

http://conserveonline.org/library/Final_English_CDERP_Report_6-13-03.pdf/view.html. Last 

accessed February 17, 2010. 

Purchase, C. E., D. Larson, M. D. Flora, and J. Reber. 2001. Amistad National Recreation Area, Texas: 

Water resources scoping report. National Park Service Technical Report NPS/NRWD/NRTR—

2001/295. National Park Service, Fort Collins, Colorado. 

Rapport, D. J. 1998. Defining ecosystem health. Pages 18–33 in D. J. Rapport, R. Costanza, P. R. Epstein, 

C. L. Gaudet, and R. Levins, eds., Ecosystem health. Malden, Ma.: Blackwell Science. 

Reid, W. H. 1979. Catalog of White Sands National Monument plant specimens in the University of 

Texas, El Paso Herbarium. Unpublished technical report, National Park Service, White Sands 

National Monument, New Mexico. 

Reid, W. H., and M. H. Reiser. 2005. Water resource information and assessment report, Phase I. 

Chihuahuan Desert Network, Las Cruces, New Mexico. 

Reynolds, J. F., P. R. Kemp, K. Ogle, and R. J. Fernandez. 2004. Modifying the ‘pulse-reserve’ paradigm 

for deserts of North America: precipitation pulses, soil water, and plant responses. Oecologia 

141:194–210. 

Rich, T. C., C. J. Beardmore, H. Berlanga, P. Blancher, M. S. W. Bradstreet, G. S. Buthcher, D. W. 

Demarest, E. H. Dunn, C. W. Hunter, E. E. Inigo-Elias, and others. 2004. Partners in Flight North 

American landbird conservation plan. Cornell Lab of Ornithology, Ithaca, New York. 
140 

Ricketts, T. H., E. Dinerstein, D. M. Olson, C. J. Loucks, W. Eichbaum, D. DellaSala, K. Kavanagh, P. 

Hedao, P. T. Hurley, K. M. Carney, and others. 1999. Terrestrial ecoregions of North America: A 

conservation assessment. Washington, D.C.: Island Press. 

Roback, P. J., and R. A. Askins. 2005. Judicious use of multiple hypothesis tests. Conservation Biology 

19:261–267. 

Rodriguez-Iturbe, I. 2000. Ecohydrology: A hydrologic perspective of climate-soil-vegetation dynamics. 

Water Resources Research 36:3–9. 

Roman, C. T., and N. E. Barrett. 1999. Conceptual framework for the development of long-term 

monitoring protocols at Cape Cod National Seashore. U.S. Department of Interior, U.S. Geological 

Survey, Patuxent Wildlife Research Center, University of Rhode Island, Providence. 

Rosenblum, E. B. 2005. The role of phenotypic plasticity in color variation in Tularosa Basin lizards. 

Copeia 2005:586–596. 

Rosenblum, E. B. 2006. Convergent evolution and divergent selection: lizards at the White Sands 

ecotone. American Naturalist 167:1–15. 

Ryan, M., S. Archer, R. Birdsey, C. Dahm, L. Heath, J. Hicke, D. Hollinger, T. Huxman, G. Okin, R. 

Oren, J. Randerson, and W. H. Schlesinger. 2008. Land resources. In The effects of climate change 

on agriculture, land resources, water resources, and biodiversity: A report by the U.S. Climate Change 

Science Program and the Subcommittee on Global Change Research. Washington, D.C. 

Sakulich, J., and A. H. Taylor. 2007. Fire regimes and forest structure in a sky island mixed conifer forest, 

Guadalupe Mountains National Park, Texas. Forest Ecology and Management 241:62–73. 

Saleska, S., J. Harte, and M. Torn. 1999. The effect of experimental ecosystem warming on COB2B fluxes 

in a montane meadow. Global Change Biology 5:125–141. 

Scheaffer, R. L., W. Mendenhall, and L. Ott. 1990. Elementary survey sampling. Fourth edition. Boston: 

PWSS-Kent. 

Scheffer, M., S. Carpenter, J. Foley, C. Folke, and B. Walker. 2001. Catastropic regime shifts in 

ecosystems. Nature 413:591–596. 

Schlesinger, W. H., J. F. Reynolds, G. L. Cunningham, L. Heunneke, W. M. Jarrell, R.A. Virginia, and 

W. G. Whitford. 1990. Biological feedbacks in global desertification. Science 247:1043–1048. 

Schlesinger, W. H., S. L. Tartowski, and S. M. Schmidt. 2006. Nutrient cycling within an arid ecosystem. 

Pages 133–149 in K. M. Havstad, L. F. Heunneke, and W. H. Schlesinger, eds., Structure and 

function of a Chihuahuan Desert ecosystem. New York: Oxford University Press. 

Schmidt, J. C., B. L. Everitt, and G. A. Richard. 2003. Hydrology and geomorphology of the Rio Grande 

and implications for river rehabilitation. Pages 25–45 in G. P. Garrett and N. L. Allan, eds., Aquatic 

fauna of the northern Chihuahuan Desert: Contributed papers from a special session, Thirty-Third 

Annual Symposium, Desert Fishes Council, November 17, 2001, Sul Ross State University, Alpine, 

Texas. Museum of Texas Tech University Special Publication Number 46. 

Schmidt, R. H., Jr. 1979. A climatic delineation of the “real” Chihuahuan Desert. Journal of Arid 

Environments 2:243–250. 

Schmitz, O. J., P. A. Hamback, and A. P. Beckerman. 2000. Trophic cascades in terrestrial systems: a 

review of the effects of carnivore removals on plants. American Naturalist 155:141–153. 

Schreuder, H. T., R. Ernst, and H. Ramirez-Maldonado. 2004. Statistical techniques for sampling and 

monitoring natural resources. USDA Forest Service, Rocky Mountain Research Station, RMRSGTR-126. 
141 

Seager, P., M. Ting, I. Held, Y. Kushnir J. Lu, G. Vecchi, H. Huang, N. Harnik, A. Leetmaa, N. Lau, C. 

Li, J. Velez, and N. Naik. 2007. Model projections of an imminent transition to a more arid climate in 

southwestern North America. Science 316:1181–1184. 

Seager, W., J. Hawley, F. E. Kottlowski, and S. A. Kelley. 1987. Geology of the east half of the Las 

Cruces and northeast El Paso 2-degree sheets southern New Mexico. Geologic Map 57. New Mexico 

Bureau of Mines and Mineral Resources, Socorro, New Mexico. 

Shields, L. M. 1957. Alga and lichen stabilized surface crusts as soil nitrogen sources. American Journal 

of Botany 44:489–498. 

Simmers, I. 2003. Understanding water in a dry environment: hydrological processes in arid and semiarid zones. International Contributions to Hydrogeology 23. 

Skagen, S. K., J. F. Kelly, C. Van Riper, R. L. Hutto, D. M. Finch, D. J. Krueper, and C. P. Melcher. 

2005. Geography of spring landbird migration through riparian habitats in southwestern North 

America. Condor 107:212–227. 

Smith, S. D., T. E. Huxman, S. F. Zitzer, T. N. Charlet, D. C. Housman, J. S. Coleman, L. K. 

Fenstermaker, J. R. Seemann, and R. S. Nowak. 2000. Elevated CO2 increases productivity and 

invasive species success in an arid ecosystem. Nature 408:79–82. 

Snyder, K. A., and S. L. Tartowski. 2006. Multi-scale temporal variation in water availability: 

implications for vegetation dynamics in arid and semi-arid ecosystems. Journal of Arid Environments 

65:219–234. 

Snyder, K. A., K. A. Mitchell, and J. E. Herrick. 2006. Patterns and controls of soil water in the Jornada 

Basin. Pages 107–132 in K. M. Havstad, L. F. Heunneke, and W. H. Schlesinger, eds., Structure and 

function of a Chihuahuan Desert ecosystem. New York: Oxford University Press. 

Sokal, R. R., and F. J. Rohlf. 1995. Biometry, 3rd Edition. W.H. Freeman and Company, New York. 

Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, M. Tignor and H. L. Miller, eds. 

2007. Climate change 2007: The physical science basis. Contribution of Working Group I to the 

Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, U.K.: 

Cambridge University Press. 

Society for Range Management (SRM). 1995. New concepts for assessment of rangeland condition. J. 

Range Management 48:271–282. 

——. 1999. A glossary of terms used in range management. Society for Range Management. Denver, 

Colorado. 

Steidl, R., J. P. Hayes, and E. Schauber. 1997. Statistical power analysis in wildlife research. Journal of 

Wildlife Management 61:270–279. 

Stevens, D. L., Jr., and A. R. Olsen. 2004. Spatially balanced sampling of natural resources. Journal of the 

American Statistical Association 99:262–278.

Stevens, L. E., and A. E. Springer. 2004. A conceptual model of springs ecosystem ecology. Supplement 

III to L. Thomas, C. Lauver, M. Hendrie, N. Tancreto, J. Whittier, J. Atkins, M. Miller and A. Cully. 

Vital signs monitoring plan for the Southern Colorado Plateau Network: Phase II Report. National 

Park Service, Southern Colorado Plateau Network, Flagstaff, Arizona. 

Stotz, N. G., and R. P. Balda. 1995. Cache and recovery behavior of wild pinyon jays in northern 

Arizona. Southwestern Naturalist 40:180–184. 

Stringham, T. K., W. C. Krueger, and P. L. Shaver. 2003. State and transition modeling: An ecological 

process approach. Journal of Range Management 58:106–113. 
142 

Stringham, T. K., W. C. Krueger, and D. R. Thomas. 2001. Application of non-equilibrium ecology to 

rangeland riparian zones. Journal of Range Management 54:210–217. 

Stroud, C. P., and H. F. Strohecker. 1949. Notes on White Sands Gryllacrididae (Orthoptera). Proceedings 

of the Entomological Society of Washington 51:125–126. 

Sullivan, R. M. 1994. Micro-evolutionary differentiation and biogeographic structure among coniferous 

forest populations of the Mexican woodrat (Neotoma mexicana) in the American Southwest: A test of 

the vicariance hypothesis. Journal of Biogeography 21:369–389. 

Sullivan, S. M. P., M. C. Watzin, and W. S. Keeton. 2007. A riverscape perspective on habitat 

associations among riverine bird assemblages in the Lake Champlain Basin, USA. Landscape 

Ecology 22:1169–1186. 

Sutton, V., E. L Morse, and R. E. Mitchell. 1988. Hydrogeologic investigation at White Sands Test 

Facility (WSTF), Las Cruces, New Mexico. Abstract. New Mexico Geological Society Annual Spring 

Meeting. New Mexico Bureau of Mines and Mineral Resources 10:66. 

Szynkiewicz, A., L. M. Pratt and M. Glamoclija. 2007. Sulfur cycling in gypsum dunes from New 

Mexico: Terrestrial analogs to sulfate-eolian deposition and early diagenesis on Mars. Lunar and 

Planetary Science XXXVIII, Proceedings of the 38th Lunar and Planetary Science Conference, 

March 12–16, San Diego, California. 

Thomas, L. P., M. N. Hendrie, C. L. Lauver, S. A. Monroe, N. J. Tancreto, S. L. Garman, and M. E. 

Miller. 2006. Vital signs monitoring plan for the Southern Colorado Plateau Network. Natural 

Resource Report NPS/SCPN/NRR—2006/002. National Park Service, Fort Collins, Colorado. 

Thompson, W. L. 2002. Towards reliable bird surveys: Accounting for individuals present but not 

detected. Auk 119:18–25. 

Thompson, W. L., G. C. White, and C. Gowan. 1998. Monitoring vertebrate populations. San Diego, Ca.: 

Academic Press. 

Trujillo, D., J. Puttere, and C. Monger. 2007. Vegetation communities on gypsiferous soils, White Sands 

Missile Range, New Mexico. Unpublished technical report, U.S. Army, White Sands Missile Range, 

New Mexico. 

Urquhart, N. S., and T. M. Kinkaid. 1999. Designs for detecting trend from repeated surveys of ecological 

resources. Journal of Agricultural and Biological Environmental Statistics 4:404–414. 

USDA Natural Resources Conservation Service (USDA NRCS). 2006. Land resource regions and major 

land resource areas of the United States, the Caribbean, and the Pacific Basin. USDA Handbook 296. 

http://soils.usda.gov/survey/geography/mlra/. 

U.S. Department of the Interior (USDOI). 2008. Information technology security policy handbook. 

Version 3.1. 

Valone, T. J. 2003. Examination of interaction effects of multiple disturbances on an arid plant 

community. Southwestern Naturalist 48:481–490. 

Van Devender, T. R. 1990. Chapter 7: Late Quaternary vegetation and climate of the Chihuahuan Desert, 

United States and Mexico. In J. Betancourt, T. Van Devender and P. Martin, eds., Packrat middens: 

The last 40,000 years of biotic change. Tucson: University of Arizona Press. 

Vander Wall, S. B. 1997. Dispersal of singleleaf pinon pine (Pinus monophylla) by seed-caching rodents. 

Journal of Mammalogy 78:181–191. 

Vitousek, P. M. 1990. Biological invasions and ecosystem processes: towards an integration of population 

biology and ecosystem studies. Oikos 57:7–13. 
143 

Wallace, R. L., E. J. Walsh, M. L. Arroyo, and P. L. Starkweather. 2005. Life on the edge: Rotifers from 

springs and ephemeral waters in the Chihuahuan Desert, Big Bend National Park (Texas, USA). 

Hydrobiologia 546:147–157. 

Ward, F. A., and J. F. Booker. 2003. Economic cost and benefits of instream flow protection for 

endangered species in an international basin. Journal of the American Water Resources Association 

39:427–440. 

Ward, J. P., Jr., A. B. Franklin, S. Rinkevich and F. Clemente. 1995. Chapter 1: Distribution and 

Abundance. Pages 1–14 in U.S. Fish and Wildlife Service recovery plan for the Mexican spotted owl. 

Volume II. Albuquerque, New Mexico. 

Weltzin, J. F., M. E. Loik, S. Schwinning, D. G. Williams, P. A. Fay, B. M. Haddad, J. Harte, T. E. 

Huxmann, A. K. Knapp, G. Lin, and others. 2003. Assessing the response of terrestrial ecosystems to 

potential changes in precipitation. BioScience 53:941–952. 

Westman, W. E. 1978. Measuring the inertia and resilience of ecosystems. BioScience 28:705–710. 

Whisenant, S. G. 1999. Repairing damaged wildlands: A process-oriented landscape scale approach. 

Cambridge, U.K.: Cambridge University Press. 

White, C. A., M. C. Feller, and S. Bayley. 2003. Predation risk and the functional response of elk-aspen 

herbivory. Forest Ecology and Management 181:77–97. 

White, P. S., and S. T. A. Pickett. 1985. Natural disturbance and patch dynamics: An introduction. Pages 

3–13 in S. T. A. Pickett and P. S. White, eds., The ecology of natural disturbance and patch dynamics. 

San Diego, Ca.: Academic Press. 

Whitford, W. G. 1996. The importance of the biodiversity of soil biota in arid ecosystems. Biodiversity 

and Conservation 5:185–195. 

Whitford, W. G. 1998. Validation of indicators. Pages 205–209 in D. J. Rapport, R. Costanza, P. R. 

Epstein, C. Gaudet, and R. Levins, eds., Ecosystem health. Malden, Ma.: Blackwell Science. 

Whitford, W. G. 2002. Ecology of desert systems. San Diego, Ca.: Academic Press. 

Whitford, W. G., and B. T. Bestelmeyer. 2006. Chihuahuan desert fauna: Effects on ecosystem properties 

and processes. Pages 247–265 in K. M. Havstad, L. F. Heunneke, and W. H. Schlesinger, eds., 

Structure and function of a Chihuahuan Desert ecosystem. New York: Oxford University Press. 

Whitford, W. G., G. S. Forbes, and G. I. Kerley. 1995. Diversity, spatial variability, and functional roles 

of invertebrates in desert grassland ecosystems. Pages 152–195 in M. P. McClaran and T. R. Van 

Devender, eds., The desert grassland. Tucson: University of Arizona Press. 

Whitford, W. G., S. Dick-Peddie, D. Walters, and J. A. Ludwig. 1978. Effects of shrub defoliation on 

grass cover and rodent species in a Chihuahuan desert ecosystem. Journal of Arid Environments 

1:237–242. 

Wilkins, D. E., and D. R. Currey. 1997. Timing and extent of late Quaternary paleolakes in the TransPecos Closed Basin, West Texas and south-central New Mexico. Quaternary Research 47:306–315. 

——. 1999. Radiocarbon chronology and delta (sub 13) C analysis of mid- to late-Holocene aeolian 

environments, Guadalupe Mountains National Park, Texas, USA. The Holocene 9:363–371. 

Williams, B. K., J. D. Nichols, and M. J. Conroy. 2002. Analysis and management of animal populations. 

San Diego, Ca.: Academic Press. 

Wondzell, S. M., G. L. Cunningham, and D. Bachelet. 1996. Relationships between landforms, 

geomorphic processes, and plant communities on a watershed in the northern Chihuahuan Desert. 

Landscape Ecology 11:351–362. 
144 

Wondzell, S., and J. A. Ludwig. 1995. Community dynamics of desert grasslands: influences of climate, 

landforms, and soils. Journal of Vegetation Science 6:377–390. 

Woodley, S. 1993. Monitoring and measuring ecosystem integrity in Canadian National Parks. In J. Kay 

and G. Francis, eds., Ecological integrity and the management of ecosystems. Delray Beach, Fl.: St. 

Lucie Press. 

Zavleta, E. 2000. The economic value of controlling an invasive shrub. Ambio 29:462–467. 
145 

Glossary of Terms and Concepts 

Adaptive management—a systematic process for continually improving management policies and 

practices by learning from the outcomes of operational programs. Its most effective form – “active” 

adaptive management – employs management programs that are designed to experimentally compare 

selected policies or practices by implementing management actions explicitly designed to generate 

information useful for evaluating alternative hypotheses about the system being managed 

(http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Alluvial fan—an outspread, gently sloping mass of alluvium deposited by a stream, especially in an arid 

region where a stream issues from a narrow canyon onto a plain or valley floor. 

Anthropogenic effects—are caused by or attributed to humans. As used here, they are human influenced 

factors that cause stress in natural systems. 

Attribute—any living or nonliving feature or process of the environment that can be measured or 

estimated and that provides insight into the state of the ecosystem. The term Indicator is reserved for a 

subset of attributes that is particularly information-rich in the sense that their values are somehow 

indicative of the quality, health, or integrity of the larger ecological system to which they belong (Noon 

2003; http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Bajada—a broad, gently inclined, detrital surface extending from the base of mountain ranges into an inland basin. 

Beta-diversity—“the variation in species composition among sites in a geographic region” (Legendre 

2008). 

Biological integrity—the ability to maintain and support a balanced, integrated, adaptive community of 

organisms having a species composition, diversity, and functional organization comparable to that of the 

natural habitat of the region. 

Biota—the total fauna and flora of a region. 

Conceptual models—purposeful representations of reality that provide a mental picture of how something 

works to communicate that explanation to others. 

Degradation—an anthropogenic reduction in the capacity of a particular ecosystem or ecosystem 

component to perform desired ecosystem functions (e.g., degraded capacity for conserving soil and water 

resources). Human actions may degrade desired ecosystem functions directly, or they may do so 

indirectly by damaging the capacity of ecosystem functions to resist or recover from natural disturbances 

and/or anthropogenic stressors (derived from concepts of Whisenant 1999, Archer and Stokes 2000, 

Whitford 2002). 

Disturbance—“. . . any relatively discrete event in time that disrupts ecosystem, community, or 

population structure and changes resources, substrate availability, or the physical environment” (White 

and Pickett 1985). In relation to monitoring, disturbances are considered to be ecological factors that are 

within the evolutionary history of the ecosystem (e.g., drought). These are differentiated from 

anthropogenic factors that are outside the range of disturbances naturally experienced by the ecosystem 

(Whitford 2002). 
146 

Driver (or ecosystem/system driver)—major driving forces such as climate, fire cycles, hydrologic cycles, 

and natural disturbance events that have large scale influences on natural ecosystems. Drivers can be 

natural forces or anthropogenic (http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Ecological integrity—a concept that expresses the degree to which the physical, chemical, and biological 

components (including composition, structure, and process) of an ecosystem and their relationships are 

present, functioning, and capable of self-renewal. Ecological integrity implies the presence of appropriate 

species, populations and communities and the occurrence of ecological processes at appropriate rates and 

scales as well as the environmental conditions that support these taxa and processes 

(http://science.nature.nps.gov/im/monitor/Glossary.htm). 

Ecological Monitoring Framework—a National Park Service systems-based, hierarchical outline that 

facilitates comparisons of vital signs among parks, networks, and other programs. 

Ecological site—a kind of land with specific physical characteristics which differs from other kinds of 

land in its ability to produce distinctive kinds and amounts of vegetation and in its response to 

management (SRM 1995). 

Ecoregion— an ecoregion is a relatively homogeneous, ecologically distinctive area, which has resulted 

from a combination of geological, landform, soil, vegetative, climatic, wildlife, water and human factors 

which may be present. Ecoregions contain many landscapes with different spatial patterns of ecosystems. 

Ecosystem—a spatially explicit unit of the Earth that includes all of the organisms, along with all 

components of the abiotic environment within its boundaries (Likens 1992). 

Ecosystem health—a metaphor pertaining to the assessment and monitoring of ecosystem structure, 

function, and resilience in relation to the notion of ecosystem “sustainability” (following Rapport 1998, 

Costanza et al. 1998). A healthy ecosystem is sustainable (see Sustainable ecosystem, below). 

Ecosystem management—the process of land-use decisionmaking and land management practice that 

takes into account the full suite of organisms and processes that characterize and comprise the ecosystem. 

It is based on the best understanding currently available as to how the ecosystem works. Ecosystem 

management includes a primary goal to sustain ecosystem structure and function, a recognition that 

ecosystems are spatially and temporally dynamic, and acceptance of the dictum that ecosystem function 

depends on ecosystem structure and diversity. The whole-system focus of ecosystem management implies 

coordinated landuse decisions (http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Endemic species—any species naturally confined to a particular area or region. 

Eolian—pertaining to the wind, esp. said of such deposits as loess and dune sand. 

Ephemeral stream—A stream or reach of a stream that flows briefly only in direct response to 

precipitation in the immediate locality and whose channel is at all times above the water table. 

Equilibrium—a condition of balance between two opposing forces. 

Evapotranspiration—the portion of precipitation returned to the area through evaporation and 

transpiration. 

Focal resources—park resources that, by virtue of their special protection, public appeal, or other 

management significance, have paramount importance for monitoring regardless of current threats or 

whether they would be monitored as an indication of ecosystem integrity. Focal resources might include 
147 

ecological processes, such as deposition rates of nitrates and sulfates in certain parks; or they may be a 

species that is harvested, endemic, alien, or has protected status. 

Focal species/organisms—species and/or organisms that play significant functional roles in ecological 

systems by their disproportionate contribution to the transfer of matter and energy, by structuring the 

environment and creating opportunities for additional species and/or organisms, or by exercising control 

over competitive dominants and thereby promoting increased biological diversity (derived from Noon 

2003). Encompasses concepts of keystone species, and umbrella species. 

Functional groups—groups of species that have similar effects on ecosystem processes (Chapin et al. 

1996); frequently applied interchangeably with functional types. 

Generalized Random-Tessellation Stratified (GRTS)—allows for a spatially-balanced random draw of 

sample units with variable inclusion probabilities and an ordered list of sample units that can support 

additions and deletions of sample units while retaining spatial balance. 

Geomorphic—pertaining to the shape of the earth or its surface features. 

Habitats—areas that provide specific conditions (e.g., temperature, moisture, soils, vegetation, and cover) 

necessary to support a community of organisms adapted to life under those conditions. 

Hydrologic function (lotic and lentic systems)—capacity of an area to: dissipate energies associated with 

(1) high stream flow (lotic); or (2) wind action, wave action, and overland flow (lentic); thereby reducing 

erosion and improving water quality; filter sediment, capture bedload, and aid floodplain development; 

improve flood-water retention and groundwater recharge; develop root masses that stabilize stream banks 

against cutting action; develop diverse ponding and channel characteristics to provide the habitat and the 

water depth, duration, and temperature necessary for fish production, waterfowl breeding, and other uses; 

support greater biodiversity (Prichard et al. 1998). 

Hydrologic function (upland systems/soils)—capacity of a site to capture, store, and safely release water 

from rainfall, run-on, and snowmelt, to resist a reduction in this capacity, and to recover this capacity 

following degradation (Pellant et al. 2000). 

Indicators—a subset of monitoring attributes that are particularly information-rich in the sense that their 

values are somehow indicative of the quality, health, or integrity of the larger ecological system to which 

they belong (Noon 2003). Indicators are a selected subset of the physical, chemical, and biological 

elements and processes of natural systems that are selected to represent the overall health or condition of 

the system (Noon 2003, http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Indicators of ecosystem health—measurable attributes of the environment (biotic or a biotic) that provides 

insights regarding (1) the functioning status of one or more key ecosystem processes, (2) the status of 

ecosystem properties that are clearly related to these ecosystem processes, and/or (3) the capacity of 

ecosystem processes or properties to resist or recover from natural disturbances and/ or anthropogenic 

stressors (modified from Whitford 1998). In the context of ecosystem health, key ecosystem processes 

and properties are those that are closely associated with the capacity of the ecosystem to maintain its 

characteristic structural and functional attributes over time (including natural variability). 

Intermittent stream—A stream or reach of a stream that flows only at certain times of the year, as when it 

receives water form springs or from some surface source. 

Invasive species—A species that is non-native to the ecosystem under consideration and whose 

introduction causes or is likely to cause economic or environmental harm, or harm to human health 
148 

(Executive Order 13112; http://www.invasivespecies.gov/laws/execorder.shtml). Invasive species can be 

plants, animals, and other organisms (e.g., microbes). Human actions are the primary means of invasive 

species introductions. 

Inventory—an extensive point-in time survey to determine the presence/absence, location or condition of 

a biotic or abiotic resource (http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Karst—an area of limestone formations characterized by sinks, ravines, and underground streams. 

Landscape—a spatially structured mosaic of different types of ecosystems interconnected by flows of 

materials (e.g., water, sediments), energy, and organisms. 

Measures—specific feature(s) used to quantify an indicator, as specified in a sampling protocol. For 

example, pH, temperature, dissolved oxygen, and specific conductivity are all measures of water 

chemistry (http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Metadata—Data about data. Represents the set of instructions or documentation that describe the content, 

context, quality, structure, and accessibility of a data set (Michener et al. 1997). 

Microclimate—A local atmospheric zone where the climate differs from the surrounding area 

(Wikipedia). 

Monitoring—collection and analysis of repeated observations or measurements to evaluate changes in 

condition and progress toward meeting a management objective (Elzinga et al. 1998). Detection of a 

change or trend may trigger a management action, or it may generate a new line of inquiry. Monitoring is 

often done by sampling the same sites over time, and these sites may be a subset of the sites sampled for 

the initial inventory (http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Natural variability—the ecological conditions, and the spatial and temporal variation in these conditions, 

that are relatively unaffected by people, within a period of time and geographical area appropriate to an 

expressed goal (Landres et al. 1999). 

Panel—A group of sample units that will always be sampled during the same sampling occasion or time 

period (McDonald 2003). 

Perennial stream—a stream or reach of a stream that flows continuously throughout the year and whose 

upper surface generally stands lower than the water table in the region adjoining the stream (Jackson 

1997). 

Phenology—term referring to the timing of an organisms lifecycle (e.g., producing flowers) only with 

certain periods of light. 

Physiography—study of the natural features of the earth’s surface including land formation, climate, 

currents, and distribution of flora and fauna. Also known as physical geography. 

Playa—a term used in the southwestern US for a dry, barren area in the lowest part of an undrained desert 

basin, underlain by clay, silt, or sand and commonly by soluble salts. It may be marked by an ephemeral 

lake. 

Population (Target)—total collection of sample units. 

Probability sampling—where each sampling unit in the finite population has a known probability (a 

selection probability) of being included in a sample. 
149 

Protocols—are detailed study plans that provide rationale for monitoring a Vital Sign, and provide 

instructions for carrying out the monitoring. Protocols consist of a narrative, standard operating 

procedures, and supplementary materials (Oakley et al. 2003). 

Rangeland—land on which the indigenous vegetation is predominantly grasses, grass-like plants, forbs, or 

shrubs and is managed as a natural ecosystem. Rangelands include natural grasslands, savannas, 

shrublands, many deserts, tundra, alpine communities, marshes and wet meadows (SRM 1999). For 

purposes of this document, we further include pinyon-juniper woodlands and oak woodlands in this 

definition. 

Reach or Stream reach—A continuous part of a stream between two specified points 

(http://water.usgs.gov/pubs/circ/circ1208/glossary.htm). 

Resilience—the capacity of a particular ecological attribute or process to recover to its former reference 

state or dynamic after exposure to a temporary disturbance and/or stressor (adapted from Grimm and 

Wissel 1997). The ability of a natural ecosystem to restore its structure following acute or chronic 

disturbance (Westman 1978). Resilience is a dynamic property that varies in relation to environmental 

conditions (Scheffer et al. 2001). 

Resistance—the capacity of a particular ecological attribute or process to remain essentially unchanged 

from its reference state or dynamic despite exposure to a disturbance and/or stressor (adapted from 

Grimm and Wissel 1997). Resistance is a dynamic property that varies in relation to environmental 

conditions (Scheffer et al. 2001). 

Responses—measurements taken on sample units. 

Riparian—pertaining to or situated on the banks of a body of water, especially a river. 

Sample—the collection of responses from the chosen sample units. 

Sample unit—predefined spatial entities in which measurements are taken. 

Sampling frame—the pool from which samples are selected in order to make references to the entire 

population (sampled and unsampled). 

Soil/Site stability—the capacity of a site to limit redistribution and loss of soil resources (including 

nutrients and organic matter) by wind and water (Pellant et al. 2000). 

Status—as used in this program, refers to the condition of a resource or vital sign at a given point in time. 

Strata—artificial constructs defined prior to sample selection that should never change, regardless of 

conditions on the ground (Geissler and McDonald 2003). 

Stressor—physical, chemical, or biological perturbations to a system that are either (a) foreign to that 

system or (b) natural to the system but applied at an excessive (or deficient) level (Barrett et al. 1976). 

Stressors cause significant changes in the ecological components, patterns and processes in natural 

systems. Examples include water withdrawal, pesticide use, timber harvesting, traffic emissions, stream 

acidification, trampling, poaching, land use change, and air pollution 

(http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Threshold—as applied to state-and transition models, a threshold is a point “. . . in space and time at 

which one or more of the primary ecological processes responsible for maintaining the sustained 

(dynamic) equilibrium of the state degrades beyond the point of self-repair. These processes must be 
150 

actively restored before the return to the previous state is possible. In the absence of active restoration, a 

new state is formed” (Stringham et al. 2003). Thresholds are defined in terms of the functional status of 

key ecosystem processes and are crossed when capacities for resistance and resilience are exceeded. (Also 

see state and transition.) 

Tinaja—a type of waterpocket formed by the weathering and erosion of a rock basin over time. Typically, 

tinajas form in incipient or established drainages that are mostly ephemeral or intermittent, and are recharged by precipitation from storms. 

Transition—as applied to state-and transition models, a transition is a trajectory of change that is 

precipitated by natural events and/or management actions which degrade the integrity of one or more of 

the primary ecological processes responsible for maintaining the dynamic equilibrium of the state. 

Transitions are vectors of system change that will lead to a new state without abatement of the stressor(s) 

and/or disturbance(s) prior to exceeding the system’s capacities for resistance and resilience (adapted 

from Stringham et al. 2003). 

Trend—as used by this program, refers to directional change measured in resources by monitoring their 

condition over time. Trends can be measured by examining individual change (change experienced by 

individual sample units) or by examining net change (change in mean response of all sample units) 

(http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Trophic—describes the position that an organism occupies in a food chain (i.e., what it eats and what eats 

it). 

Variable—any quantitative aspect of an object of concern. 

Vital signs—a subset of physical, chemical, and biological elements and processes of park ecosystems 

that are selected to represent the overall health or condition of park resources, known or hypothesized 

effects of stressors, or elements that have important human values. The elements and processes that are 

monitored are a subset of the total suite of natural resources that park managers are directed to preserve 

“unimpaired for future generations,” including water, air, geological resources, plants and animals, and 

the various ecological, biological, and physical processes that act on those resources. Vital signs may 

occur at any level of organization including landscape, community, population, or genetic level, and may 

be compositional (referring to the variety of elements in the system), structural (referring to the 

organization or pattern of the system), or functional (referring to ecological processes) 

(http://science.nature.nps.gov/im/monitor/Glossary.cfm). 

Watershed—a drainage basin, usually described as into a river or lake. 

Xeric—being deficient in moisture, as in, deserts provide xeric environments. 
The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides 

scientific and other information about those resources; and honors its special responsibilities to American Indians, 

Alaska Natives, and affiliated Island Communities. 

NPS 960/101911, April 2010 
National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 

Natural Resource Program Center 

1201 Oak Ridge Drive, Suite 150 

Fort Collins, Colorado 80525 

www.nature.nps.gov 

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