A Science Strategy for

**Ecosystem Health, Sustainability, and Land Surface Change**
**Research**

Thomas R. Loveland, USGS EROS Data Center, Sioux Falls, SD

Glenn Guntenspergen, USGS, Duluth, MN

Ellen A. Raabe, USGS Center for Coastal Geology, St. Petersburg, FL

Marcus C. Waldron, USGS, Northborough, MA

Raymond D. Watts, USGS Midcontinent Ecological Science Center, Fort
Collins, CO

######## Report Table of Contents {#report-table-of-contents .unnumbered}

[***Executive Summary*** 2](#executive-summary)

[***The Need and the Vision*** 2](#the-need-and-the-vision)

[***Science Goal and Overarching Objectives***
2](#science-goal-and-overarching-objectives)

[***Projected Infrastructure Needs***
6](#projected-infrastructure-needs)

[***Summary*** 7](#summary)

[**Introduction** 7](#introduction)

[**Vision** 8](#vision)

[**Science Goal and Overarching Objectives**
8](#science-goal-and-overarching-objectives-1)

[**Guiding Principles for Ecosystem Health, Sustainability, and Land
Surface Change**
10](#guiding-principles-for-ecosystem-health-sustainability-and-land-surface-change)

[**USGS and the Science of Change** 11](#usgs-and-the-science-of-change)

[**Basic Terminology** 12](#basic-terminology)

[**Science Strategy Report Layout** 13](#science-strategy-report-layout)

[**Background** 14](#background)

[**The Nature of the Problem: Land Surface Change**
14](#the-nature-of-the-problem-land-surface-change)

[**The Nature of the Problem: Consequences of Land Surface Change on
Ecosystem Health**
16](#the-nature-of-the-problem-consequences-of-land-surface-change-on-ecosystem-health)

[**The Scientific Call for Ecosystem Health, Sustainability, and Land
Surface Change Research**
17](#the-scientific-call-for-ecosystem-health-sustainability-and-land-surface-change-research)

[**Summary Perspectives** 19](#summary-perspectives)

[**Science Questions** 19](#science-questions)

[**Ecosystems Issues** 20](#ecosystems-issues)

[**Land Surface Change** 25](#land-surface-change)

[**Integration, Assessment, and Monitoring**
29](#integration-assessment-and-monitoring)

[**Projected Infrastructure Needs**
32](#projected-infrastructure-needs-1)

[**Organization** 32](#organization)

[**Staffing, Skills, and Strategies**
33](#staffing-skills-and-strategies)

[**Facilities** 33](#facilities)

[**Long-Term Datasets** 34](#long-term-datasets)

[**Complementary Programs** 34](#complementary-programs)

[**Implementation Considerations: Beginning with the End in Mind**
36](#implementation-considerations-beginning-with-the-end-in-mind)

[**Summary** 37](#summary-1)

[**References** 39](#references)

[**List of Tables** 46](#list-of-tables)

[**List of Figures** 50](#list-of-figures)

#  {#section .unnumbered}

# ***Executive Summary*** {#executive-summary .unnumbered}

## ***The Need and the Vision***

Healthy ecosystems enhance our environmental, economic, and social ways
of life. The citizens and leadership of the United States envision
managing growth and change so that the ecological integrity and goods
and services provided by the Nation's ecosystems are sustained for
present and future generations. Unfortunately, our ecosystems have been
fragmented and degraded by a number of stressors, with human activities
-- as manifested by land use change -- leading the list. In order to
improve the health and sustainability of our ecosystems, it is essential
that the underlying science of ecosystem functioning and land surface
change be better understood. As the provider of "Science for a Changing
World", the U.S. Geological Survey (USGS) must undertake an aggressive
science program that enables citizens, resource managers, and decision
makers to understand the opportunities for improving and sustaining
ecosystem health. [By 2010, we expect that the USGS will have an
operational capability to routinely assess the status and trends of our
Nation's ecosystems, and to forecast their status for a period into the
future.]{.underline} This report lays out a vision that establishes an
improved scientific basis, reflected in new models, maps,
visualizations, and decision support tools, together with easily
accessible, integrated information and scientific knowledge, that help
the Nation's citizens and leadership understand the benefits and costs
associated with management actions that can alter landscapes and the
ecosystems they support.

## ***Science Goal and Overarching Objectives***

The goal of this science initiative is to document past and present
changes to the land surface, to develop conceptual ecosystem models, to
develop a methodology for predictive modeling of ecosystem health and
sustainability, and to assess the condition and status of our Nations
ecosystems and the resources they provide.

This goal is framed by three overarching questions that form the
integral relationship between ecosystem health and sustainability and
land surface change:

-   In the absence of humans, how would the form and function of an
    ecosystem evolve?

-   In the presence of humans, assuming that we maintain the current
    configuration of the landscape, how will the form and functions of
    the natural elements of ecosystems evolve?

-   In the presence of humans, and assuming continued land use change,
    what will happen to the form and functions of the natural remnants
    of ecosystems?

To achieve the goal and answer the three overarching questions, the USGS
must address a significant number of scientific questions relating to
ecosystem form and function, land surface change, and
analysis/integration methods. The questions and associated actions
include:

*How should we define ecosystems?*

[Action]{.underline}: Develop new conceptual models of ecosystems that
explicitly recognize the hierarchical organization of ecosystem
properties and directly relate ecosystem components to observable
macroscopic system behaviors; pursue understanding of the role of
biodiversity in determining ecosystem responses to external
environmental change.

*What is the relationship between biological diversity and ecosystem
structure and function?*

[Actions]{.underline}: Initiate empirical studies that advance our
understanding of the role of individual species in ecosystem processes.
Facilitate basic research on the interaction between community level
processes and ecosystem function.

*What is the role of spatial heterogeneity within and among ecosystems
to the functioning of individual ecosystems and of entire regions?*

[Actions]{.underline}: We need to develop the appropriate remote sensing
and Geographic Information System (GIS) technologies that permit
examination of spatial patterns at appropriate spatial scales.

*How do the type, intensity, and duration of disturbance affect the
characteristics of ecosystems?*

[Actions]{.underline}: Experimental perturbations of the appropriate
scale, intensity, and type are essential for the evaluation and
comparison of alternative management strategies to disturbance. New
generations of ecological models must be developed that analyze the
dynamics of ecosystems at landscape scales.

*What are the time scales of important ecological processes?*

[Actions]{.underline}: Long-term multidisciplinary studies and the
development of new techniques to reconstruct past communities and
landscapes will be necessary to understand the appropriate time scales
for ecosystem response.

*What are the mechanisms linking processes operating at different
temporal scales within ecosystems? What are appropriate scaling
strategies for investigating these processes?*

[Action]{.underline}: Investigate relations between ecosystem components
and whole-system behaviors; elucidate rules of ecosystem organization
and show how organization is related to function.

*What allows ecosystems and ecosystem processes to persist in the face
of perturbations?*

[Actions]{.underline}: Research programs must be initiated that
explicitly address how different stresses affect ecosystem functions
within and among systems. We need to compare how different ecosystems
respond to similar stresses. Long-term studies that establish baseline
variability for ecosystems and long-term research sites present the best
opportunities to address this question.

*What measures of ecosystem behavior might best be used to track
responses to ecosystem stresses?*

[Action]{.underline}: Identify ecosystem processes that indicate
whole-system responses to stress; investigate relations between
whole-systems responses and ecosystem components; develop methods for
real-time monitoring of ecosystem behavior.

*How can we predict ecosystem responses to external stresses?*

[Action]{.underline}: (1) Reconstruct Holocene climate and ecology,
identifying rates and trends and the current status of ecosystems within
the long-term picture. (2) Develop integrated models for predicting
ecosystem responses to land-surface change; provide decision-support
systems for predicting ecosystem vulnerability to environmental
disturbance.

*How have the patterns and characteristics of natural vegetation evolved
over the past 10,000 years?*

[Actions]{.underline}: Reconstruct the patterns of natural vegetation
for various climatic conditions that occurred periodically over the past
10,000 years. Through an examination of fossil, pollen, and other
records, there must be a spatially explicit mapping of the primary
natural vegetation patterns, ecosystem extents, and natural disturbance
regimes.

*How has land cover been changed by human use over the past 300 years?*

[Actions]{.underline}: (1) Develop a spatially explicit land use history
of the U.S. from pre-European settlement to the present. (2) Conduct
more detailed case histories that provide a means to understand the
detailed mechanistic components of land use and land cover change.

*Based on the past, how will changes in land use affect land cover in
the next 50 to 100 years?*

[Actions]{.underline}: (1) Develop predictive models for forecasting
land use changes and subsequent patterns under various scenarios. (2)
Based on past rates and causes of change, determine a series of
realistic scenarios of change based on logical future states.

*What are the major natural and human causes of land use change in
different geographical and historical consequences?*

[Actions]{.underline}: (1) Develop a framework for determining the
local, regional, and global driving forces of land use and land cover
change. (2) Document the major driving forces of U.S. land use change
for the past 100 years. (3) Identify episodes of combined driving forces
that had specific geographic and temporal signatures.

*How do human-induced land use and land cover changes affect ecosystem
form and function?*

[Actions]{.underline}: (1) Document the primary consequences of land use
and land cover change across the United States on ecosystem form and
function for the past 300 years. (2) Conduct an assessment of the
Nation's ecosystems to determine if the current land use activities
conducive to sustaining pre-defined ecosystem health. The three levels
specified under Overarching Questions are the logical target states for
this assessment. (3) Develop a predictive consequences model which
provides the means to estimate the consequences of land use and land
cover change on ecosystem form and function, given the local
characteristics of land use and land cover, and ecosystem status.

*What are the feedbacks between land use/cover change on climate and
biogeochemistry?*

[Action]{.underline}: Determine the affects of changing biogeochemistry
(i.e., nutrient enrichment) and climate (i.e., altered temperature and
precipitation patterns) on land use and land management practices, and
ultimately on ecosystem health under different future states scenarios
(i.e., doubling of CO~2~).

*How can we account for ecosystem processes and responses to
land-surface changes that occur over temporal scales of years to decades
to centuries?*

[Action]{.underline}: Provide mechanisms for USGS scientists to design
and conduct multi-year investigations of ecosystem responses to
environmental change.

*What methodological advances are needed to monitor ecosystem structure
and function, and land-surface change in a spatially explicit fashion?*

[Action]{.underline}:

\(1\) What are the fundamental spatial and temporal scales upon which to
monitor ecosystems (2) What spatial frameworks and overall monitoring
design should be implemented to sample ecosystems; and (3) What
ecosystem and land use and cover variables should be measured and
monitored?

*How can we put site-based studies of ecosystem processes into a spatial
context so that we can extrapolate the results of those studies over
larger geographic areas (drainage basins, landscapes, ecoregions)?*

[Action]{.underline}: (1) Develop a series of hypotheses that link site
to landscape processes and inter-ecosystem processes into larger
framework. (2) Establish a National framework with the goal of
coordinating and integrating site-based investigations of ecosystems so
that results and conclusions can be evaluated and extended to other
systems at the same or greater spatial scales.

*What is the appropriate design and implementation strategy for a
National Environmental/Ecosystems Assessment Program?*

[Action]{.underline}: Design and test a near real-time system for the
national-scale assessment of ecosystem status and trends.

The ultimate measure of success in this ecosystem health,
sustainability, and land surface change science initiative, however, is
an assessment product in which we can understand [where we have
been]{.underline}, [appreciate where we are now]{.underline}, and
visualize [where we will be 10-50 years from now]{.underline} in a given
ecosystem. The three layers of comprehension will need to be distilled
and simplified in forms suitable for policy makers and the general
public. New insights and questions are fed back into our mapping,
monitoring, and modeling phases toward a continuous evolution of
ecosystem and land surface change research.

## ***Projected Infrastructure Needs***

The infrastructure requirements associated with this initiative are
potentially vast. We are not only proposing an emphasis on basic
questions in ecosystem science and understanding the drivers of land use
change but promoting an understanding of how these changes affect
ecosystem condition and the goods and services ecosystems provide
humanity.

The unique niche of the USGS is our ability to conduct studies at
unprecedented spatial and temporal scales. Scales have a way of masking
complexity and often suppress unexpected connections. Thus, the USGS
will need to seek scientists that can span scales and operate both
locally and nationally. The complexity of this initiative reflects the
complexity of integrated science in general. The science that we
describe engages multiple disciplines in the physical, biological, and
social sciences. To ensure success there is a need:

-   To develop new skills, either through new hires or through training
    programs.

-   For increased field experiments, and greater use of spatial
    technologies (i.e., remote sensing, GIS, global positioning
    systems).

However, the most important step that needs to be taken is to establish
mechanisms that put together teams of ecosystem scientists, geographers,
and other scientists together to address the critical questions
associated with ecosystem health, sustainability, and land surface
change. There is a need to immediately institute a socialization process
where selected scientists in the various disciplines can periodically
interact and learn from each other and to identify research priorities
and to develop the specific implementation strategies implied in this
science strategy.

We suggest that this science strategy is uniquely suited to regional
implementation in which a series of ecosystems teams are established
that conduct the research in integrated teams of ecosystems, land
surface change, and integration, assessment, and monitoring scientists.
However, [it is essential that the ecosystem health, sustainability, and
land surface change science initiative be designed as a national
investigation]{.underline}. It is mandatory that there is a strong lead
center for research design, scientific oversight, and integration,
assessment, and monitoring studies.

## ***Summary***

The U.S. Geological Survey has a major opportunity and responsibility to
provide leadership in understanding the consequences of land cover and
land use change on ecosystem integrity and developing sound science that
will support assessments of ecosystem condition and performance. An
integrated research approach with a focus on ecosystem integrity,
sustainability, and land surface change is necessary. The ability to
predict future changes requires an improved understanding of the causes
and mechanisms that underlie current and past changes in land cover.
Research that investigates the functional consequences of land-cover and
land-use changes for ecosystems needs to be conducted. New research also
needs to be initiated that examines how ecosystems react to change. An
understanding of ecosystem response to changes in the factors that drive
ecosystem behavior in both natural and human dominated systems is
important in order to prescribe ecosystem restoration and management
strategies that would enhance the sustainability of Earth's ecological
systems. New tools and methodologies must be developed to strengthen the
capacity to assess the sustainability of ecosystems to provide goods and
services and the potential consequences of future changes in ecosystems.
Improved predictive models including decision support systems for
land-use planning and improved assessment of the likely outcomes of
alternative land-use scenarios must be developed that will help guide
managers in their activities.

# **Introduction** {#introduction .unnumbered}

Even a casual comparison of the pre-settlement environment with the
current landscape provides clear evidence that we live in a transformed
Nation (figure 1). The grassland ecosystems of the Great Plains have
been replaced by agricultural activities, the temperate forests of the
east are now fragments interspersed with cities, towns, and farmland,
the great wetlands of the south have been channeled and drained, and
everywhere impervious surfaces alter the flow of water and materials.
While this illustration highlights the magnitude of change to the
Nation's ecosystems, it does not adequately describe the anthropogenic
impacts on the country's natural ecosystems. At this time, we lack the
scientific basis and programmatic impetus to adequately document,
monitor, and understand the relationship between land surface change and
ecosystem health and sustainability from local to national and global
scales.

## **Vision**

This report outlines a vision for scientific research on ecosystem
health, sustainability, and land surface change. Healthy ecosystems
enhance our environmental, economic, and social ways of life. The
citizens and leadership of the U.S. envision managing growth and change
so that the ecological integrity and goods and services provided by the
Nation's ecosystems are sustained for present and future generations.
Unfortunately, our ecosystems have been fragmented and degraded by a
number of stressors, with human activities -- as manifested by land use
change -- leading the list. In order to improve the health and
sustainability of our ecosystems, it is essential that the underlying
science of ecosystem functioning and land surface change be better
understood. As the provider of "Science for a Changing World", the U.S.
Geological Survey (USGS) must undertake an aggressive science program
that enables citizens, resource managers, and decision makers to
understand the opportunities for improving and sustaining ecosystem
health. [By 2010, we expect that the USGS will have an operational
capability to routinely assess the status and trends of our Nation's
ecosystems, and to forecast their status for a period into the
future.]{.underline} This report lays out a vision that establishes an
improved scientific basis, reflected in new models, visualizations, and
decision support tools, together with easily accessible, integrated
information and scientific knowledge, that help the Nation's citizens
and leadership understand the benefits and costs associated with
management actions that can alter landscapes and the ecosystems they
support.

## **Science Goal and Overarching Objectives**

The goal of this science initiative is to [document past and present
changes to the land surface]{.underline}, to [develop conceptual
ecosystem models]{.underline}, to [develop a methodology for predictive
modeling of ecosystem health and sustainability]{.underline}, and to
[assess the condition and status of our Nations ecosystems and the
resources they provide]{.underline}.

This goal is framed by three overarching questions that form the
integral relationship between ecosystem health and sustainability and
land surface change. Because the status of ecosystems is increasingly
dependent upon the extent of human-initiative land surface change, it is
necessary to take a holistic but sequential look at ecosystems. The
three overarching questions that must be answered are:

-   In the absence of humans, how would the form and function of an
    ecosystem evolve?

-   In the presence of humans, assuming that we maintain the current
    configuration of the landscape, how will the form and functions of
    the natural elements of ecosystems evolve?

-   In the presence of humans, and assuming continued land use change,
    what will happen to the form and functions of the natural remnants
    of ecosystems?

Ecosystems health and sustainability science requires parallel
measurement, monitoring, and understanding of human modification of the
Earth, as well as science that is integrated with a broad range of
biological, earth, atmospheric, and marine sciences (Vitousek 1997).
Ultimately, because the human species is and will remain part of
ecosystems, it is also necessary to consider what adjustments can be
made to socio-economic conditions, institutional directions, or land and
water use practices to provide a base for sustaining the greatest form
and function of the local/natural ecosystem (creation, restoration,
community involvement, new paradigms). This initiative provides the
scientific basis to address these very challenging societal issues.

To achieve the goal and answer the three overarching questions, the USGS
must address a significant number of scientific questions relating to
ecosystem form and function, land surface change, and
analysis/integration methods. Those questions are identified and
described in the section on Science Questions. Collectively, the
questions will provide the comprehensive background that will permit the
USGS to implement three essential components for ecosystem status and
trends assessments: [mapping, monitoring and investigation, and
modeling]{.underline}. Combined, the three components will lead to an
[assessment]{.underline} and to the [communication]{.underline} of the
assessment in forms suitable for policy makers and the general public
(figure 2). This document aims not to outline details for specific
ecosystems, but to outline the steps necessary for the USGS to prepare
staff, facilities, and resources for a complex and long-term effort. We
believe that the measures of success for the science investigations
presented in this report will become clear when we are able to:

-   Assess the current condition and status of the Nation's ecosystems

-   Map past and present land surface change

-   Identify forcing factors, rates and trends

-   Identify thresholds for irreversible change

-   Evaluate ongoing natural and human processes and their influence on
    ecosystem health and sustainability

-   Develop methodology for extrapolating between small and large scale
    research activities

-   Develop methodology to link adjacent ecosystems

-   Develop a predictive model for ecosystem health and sustainability

The ultimate measure of success in this ecosystem health,
sustainability, and land surface change science initiative, however, is
an assessment product in which we can understand [where we have
been]{.underline}, [appreciate where we are now]{.underline}, and
visualize [where we will be 10-50 years from now]{.underline} in a given
ecosystem. The three layers of comprehension will need to be distilled
and simplified in forms suitable for policy makers and the general
public. New insights and questions must be fed back into our mapping,
monitoring, and modeling phases toward a continuous evolution of
ecosystem and land surface change research.

## **Guiding Principles for Ecosystem Health, Sustainability, and Land Surface Change**

The scientific investigations outlined in this report share several
guiding principles that define the basic foundation for the research
that must be undertaken. Collectively, they provide the philosophical
basis for understanding the tentative scope of the proposed research.
The guiding principles for this initiative are the following:

-   Ecosystems and land surface change must be viewed using a holistic
    perspective so that the full range of abiotic and biotic elements,
    including humans, are considered.

-   The research should be viewed from local to regional, national, and
    global scales and venues. Because local decisions have global
    impacts, and global processes have local consequences, it is
    necessary for the research to span all scales.

-   Ecosystem and land surface change research should be designed
    globally and implemented locally and regionally. Only with this
    approach will we be able to compare, contrast, link, and draw
    lessons from different geographic regions.

-   Ecosystems are viewed as being: (1) comprehensive, meaning that they
    include aquatic and terrestrial, near-shore and inland, and
    below-ground and above-ground components; and (2) exhaustive,
    meaning that ecosystems form a patchwork of interlocking landscapes
    that completely covers the Earth.

-   Boundaries, or ecotones, are important laboratories for monitoring
    the process of environmental change.

-   Socio-economic considerations influence all aspects of ecosystem and
    land surface change issues (figure 3). Therefore, a socio-economic
    research component is vital to the full suite of proposed research
    issues.

-   Integrated but diverse scientific perspectives are essential. This
    means that all relevant disciplines should pursue those components
    of the research they are best suited to address, but within the
    bounds of closely-integrated team. The research team does not have
    to think alike, for that would stifle the creativity of the
    research. However, the team must be organized so that it can think
    together.

-   Dynamic flow components, including hydrologic, atmospheric, and
    anthropogenic flows of material, nutrients, contaminants, resources,
    energy, and ideas are essential due to the fact that this research
    plan is largely focused on dynamics.

-   Research must be collaborative to be successful. That means that the
    science undertaken as part of this strategy should span USGS
    disciplines, other federal agencies, academia, and non-governmental
    organizations.

-   Modeling provides a means to understand complex biological,
    physical, and social processes within past, present, and future
    contexts. Modeling, coupled with monitoring and mapping, are an
    important suite of tools providing data and information for the
    understanding of ecosystem health, sustainability, and land surface
    change.

-   Quantitative measurement and analysis must be used to document and
    test the significance of ecosystem and land surface change
    processes. However, qualitative and observational analyses are also
    important ways to interpret and understand biological processes,
    including human activities.

-   Validation and verification must be essential design elements in all
    aspects of the research so that the results have undisputed meaning.

## **USGS and the Science of Change**

The USGS mission is focused on the science of change. Since the
establishment of the USGS in the late-19^th^ Century, bureau geologists
have pieced together the story, patterns, and characteristics of the
Earth's formation, and have an ongoing effort to understand modern
geological natural hazards. The early mapping and exploration of the
Nation by USGS explorers, cartographers, and scientists documented the
national landscape for purposes of enabling change -- e.g., westward
expansion and settlement. The archive of USGS maps serve as a permanent
record of the changing face of the Nation over the past 120 years. Now,
with the addition of biologists, the USGS is poised to redefine and
expand a 21^st^ Century [Science of Change]{.underline}.

In a recent report on future roles and responsibilities for the USGS,
the addition of biological science was identified as one of the more
radical changes in the bureau's 120-year history (National Research
Council 2001a). This expansion in capabilities and perspective, combined
with the societal recognition of the serious threats to the integrity of
ecosystems caused by land use change, places the USGS in the unique
position to undertake a major science initiative that can potentially
minimize threats to the Nation's biological resources. Now we can couple
the Earth's geological history with a contemporary characterization and
assessment of our evolving natural ecosystems -- considering the
unprecedented role of humans and the modern-day agents of change (Bryce,
et al. 1999). The USGS motto is "Science for a Changing World." Change,
whether geologic, hydrologic, biologic, or geographic, is the business
of the USGS. This science plan provides direction for adding the last
two disciplines, biology and geography, to the integrated science
mission of the agency with a focus on ecosystem health, sustainability,
and land surface change.

A specific challenge offered in the National Research Council (NRC)
document is the initiation of research that contributes to the sound
management of the Earth's ecosystems, and especially, research that
leads to the maintenance of biodiversity and ecosystem function (NRC
2001a). The NRC USGS report also suggests that the USGS undertake
research on the significant ecological consequences of land and water
use changes. Documenting these changes and studying the mechanisms by
which they influence existing systems were identified as important to
the Nation's economy and to the protection of a suite of natural
ecosystems. The report states that the USGS has the capability to play a
strong role as a source of information on ecosystems in the future and
to capitalize on society's interest in the conservation of biodiversity,
the potential effects of climate change, the cause of the invasion and
spread of non-native species, and the sustainability of the biosphere.
Finally, the NRC USGS report concludes that the development and
availability of long-term monitoring data are especially important in
the biological sciences, since USGS is one of the few entities that has
the capacity to carry out this work over long periods. The NRC argues
that these long-term databases should one of the most important USGS
contributions to the Nation.

## **Basic Terminology**

The complex scope of this science strategy requires definition so that
there is a clear understanding of the focus and scope of the proposed
research. For clarity, we offer the following definitions:

-   [Ecosystems]{.underline} are functional spatial regions that result
    from the interactions of abiotic, biotic, and anthropogenic
    components (Elben and Elben 1994). Ecosystems are ecological systems
    that consist of a combination of interacting, interrelated parts
    that form an integrated, functional whole.

-   We define [ecosystem health]{.underline} as the relative ability of
    an ecosystem to resist significant internal change in the face of
    external perturbation or to return to a predisturbance state
    following perturbation. Costanza (1992) suggests that an ecosystem
    is healthy when under stress it maintains its internal structure and
    organization.

-   [Ecological sustainability]{.underline} is the degree to which the
    interactions between humans and nature will be balanced over the
    long term, or will lead to environmental or ecological degradation
    (e.g., an imbalance will lead to deteriorating ecosystem health).

-   A series of [indicators]{.underline} are typically monitored in
    order to determine ecosystem health and sustainability. Two common
    measures of ecosystem health are biodiversity and ecosystem
    productivity. Land use change is typically monitored as an indicator
    of ecosystem [stress]{.underline}.

-   [Land surface change]{.underline} refers to the modification of land
    and/or water resources. This may include removing or adding
    vegetation, structures, or water (land cover), or disturbing the
    surface and subsurface. The agents of land surface change can be
    human-caused or induced, or the result of natural processes (i.e.,
    storms, flooding, geological hazards, etc.).

-   Two specific forms of land surface change are changes to land use
    and land cover. [Land use]{.underline} is the activity for which the
    land is used (e.g., farming, grazing, logging, recreating, commerce,
    etc.), while [land cover]{.underline} is the vegetated and
    non-vegetated cover (e.g., wheat, grassland, forest, water bodies,
    buildings, etc.). Land use change typically changes land cover.

## **Science Strategy Report Layout**

This science strategy outlines an agenda for a coupled and balanced
investigation of ecosystem health, sustainability, and land surface
change. With such a potentially broad topic, it would be natural and
perhaps even practical to emphasize just the cause (e.g., land surface
change), or just the consequence (e.g., ecosystem health and
sustainability). However, there is such a strong connection between land
surface change and ecosystem health and sustainability, it is essential
to keep the "horse (land surface change) connected to the cart
(ecosystem health)". Whether ecosystem changes are the result of natural
events such as windstorms and landslides, or are the result of human
activity, such as deforestation or pollution of streams, they are
undergoing change. It is important to recognize that human-induced
changes to ecosystems are more extensive and rapid than the slower
evolutionary changes on ecosystem capacity and character that are caused
by climatic or geologic changes (Bryce, et al. 1999).

In following section of this report, we will present an overview of the
nature of the problem regarding ecosystem health, sustainability, and
land surface change. The following section presents the core science
issues associated with this topic -- expressed as science questions.
Each question includes a discussion of the central issues and important
actions. The implementation and infrastructure issues and science
priorities that must be undertaken follows. Finally, we end with a
summary of the critical points of this report.

# **Background** {#background .unnumbered}

Ecosystem change has occurred since the beginning of life on Earth.
Changes resulted from natural succession, with periodic perturbations
caused by natural events such as lightening-caused fire, flooding, wind
storms, and landslides. Today, there is increased recognition that land
use change is a major driver of a wide spectrum of environmental
consequences, through its interaction with ecosystem processes,
biogeochemical cycles, biodiversity and climate (Nunes and Augé 1999).
Local land use patterns, formed by a variety of biophysical and social
processes, result in land cover changes that affect ecosystem health,
including unexpected and unwanted changes in biodiversity, productivity,
water and radiation budgets, and trace-gas emissions. Cumulatively,
these changes on local ecosystems can alter the global climate and
biosphere (Riebsame et al. 1994).

What induced humans to cause such dramatic change? It was the desire to
extract ecosystem goods and services (ecosystem benefits) for
subsistence or for profit. In the past, this use of ecosystems focused
on single objectives such as food production or timber supply. Quite
obviously, the costs in human energy and capital provided, at least in
the short term, benefits that exceeded costs. Our historical approach to
managing ecosystems is no longer appropriate when ecosystem management
must address conflicting goals and take into account local to global
environmental problems. The increasing demand for ecosystem goods and
services is associated with significant social and economic costs. The
value of ecological benefits is potentially vast. Costanza et al. (1997)
estimated the global value of goods and services provided by ecosystems
to be \$33 trillion per year, and suggested that the \$33 trillion
estimate was low side due to exclusion of nonrenewable resource
extractions and omission of several ecosystems. What is particularly
noteworthy about this calculation is that the global economy, by
traditional measures, produces \$18 trillion of goods and services.
Thus, ecosystem benefits may outweigh "traditional" economic goods and
services by a factor of nearly two.

## **The Nature of the Problem: Land Surface Change**

Fundamental to this science strategy is the connection between ecosystem
form and function and land surface characteristics. If form makes
evident the function, then the functioning of the system may be
monitored, measured, and assessed by observing changes in the form.
However, this approach may be applied successfully only when the
manifestation of biological and physical processes in form is
understood. Documentation and evaluation of land surface change may be
used as an "indicator" of ecosystem health and sustainability.

We must accelerate our efforts to understand Earth\'s ecosystems and how
they interact with the many dimensions of natural- and human-caused
landscape change. It is essential to recognize that ecological research
is complex and demanding and must include a comprehensive strategy that
includes measurement and monitoring of populations and ecosystems, and
experimental studies to elucidate the regulation of ecological
processes. Also needed are the development, testing, and validation of
local, regional, and global ecological processes models. Equally
important is that ecosystem health and sustainability science
initiatives require parallel measurement, monitoring, and understanding
of human modification of the Earth, as well as science that is
integrated with a broad range of biological, earth, atmospheric, and
marine sciences (Vitousek 1997).

There is considerable urgency due to the unprecedented rates of land
surface change and the corresponding impacts on biological resources.
Evidence of environmental change is plentiful. Consider, for example,
that expansion of agricultural land is now widely recognized as one of
the most significant human alterations to the global environment. The
total area of cultivated land worldwide increased 466% from 1700 to 1980
(Matson et al. 1997). At the global scale, lands used for cropping
encompasses nearly 28 million km^2^, or approximately 19 percent of the
Earth's land surface (Loveland 2000). Only forests cover a larger area
of the global land surface (40 million km^2^ or 27 percent). While the
transformation of wild lands to croplands has slowed in the last three
decades, agricultural practices have intensified, and yields (food
produced per area of land) have increased dramatically and have
out-paced global human population growth. There is clear evidence that
agricultural intensification can have negative local consequences, such
as increased erosion, lower soil fertility, and reduced biodiversity;
negative regional consequences, such as pollution of ground water and
eutrophication of rivers and lakes, as well as negative global
consequences, including impacts on atmospheric constituents and climate
(Matson et al. 1997). In the Prairie Pothole Region of the United
States, over 50% of the surviving wetlands are surrounded by lands used
for agricultural activity (Guntenspergen, unpublished data) and
subjected to nutrient runoff, sediment erosion, and exposure to
herbicides and pesticides.

If we consider landscape change in the United States, we note that
almost half of the conterminous 48 states were covered with forests
prior to European settlement. Forest area began a significant decline
with the onset of European settlement and continued until the early 20th
century. From an estimated 36.4 million km^2^ in 1850, the entire U.S.
reached a low point of 24.3 million km^2^ around 1920. It then rose
slowly until around 1960, then began a modest decline (Meyer, 1995).
Today approximately 30 percent of the conterminous U.S. is forested
(figure 4). Fifty-three percent of American wetlands were lost between
the 1780\'s and the 1980\'s, principally to drainage from agriculture.
Most of the conversion took place in the 20th century. Between the
1950\'s and 1970\'s alone, 445,000 km^2^ of wetlands were lost (Meyer,
1995).

The composition of U.S. land cover stabilized somewhat in the later half
of the 20^th^ century, though some areas are clearly undergoing
significant land use and land cover transformations. In a study by
Klopatek et al. on the impacts of land use change on natural vegetation,
they determined that 23 of the 106 natural vegetation types occurring in
the United States at the time of European Settlement have been reduced
by more than 50 percent through human-induced land use changes (1979).
In contrast, only 26 natural vegetation types have had less than 5
percent of their potential area converted to urban or agricultural land
uses. Today, we are still experiencing significant changes in land use
and land cover. The southeastern U.S. region has experienced rates of
change exceeding five percent every 6-8 years for the past 20 years,
with some ecoregions experiencing even higher rates due to the
urbanization and the transformation to plantation forestry (Table 1,
Loveland et al., 2001)

Population growth is a recognized driver of human-induced land surface
change. Since the 1960's, the population of the United States has
increased from 179 to 255 million. Although birth rates are declining or
holding steady in many regions, the U.S. Census Bureau projects a 50
percent increase in population to 383 million by the year 2050. These
figures translate into significant land use change that will likely have
major consequences on ecosystem health and sustainability. In fact,
increased national affluence, combined with ease of movement, is
generating yet another population trend that may focus degradation on
some of our most critical and currently undisturbed ecosystems. Urban
migration to small, rural communities, often adjacent to national parks
and other scenic areas, is increasing (Diamond and Noonan, 1996).

## **The Nature of the Problem: Consequences of Land Surface Change on Ecosystem Health**

The consequences of land surface change on ecosystems has proven to be
significant -- in a number of ways. For example:

-   The extent of global soil degradation induced by human activity
    since 1945 is estimated to affect 20 million km^2^, or 14 percent of
    Earth's land area. The percent of area affected appears to be
    independent of ecological zone or economic status. Overgrazing is
    the leading cause of degradation (35%), followed by deforestation
    (30%), and other agriculture (28%) (Daily 1995).

-   Recent calculations suggest that rates of species extinction are now
    on the order of 100 to 1000 times those before human dominance of
    Earth. At present, 11 percent of the remaining birds, 18 percent of
    the mammals, 5 percent of fish, and 8 percent of plant species on
    Earth are threatened with extinction (Vitousek 1997).

-   In addition to extinction, people have caused a rearrangement of
    Earth\'s biotic systems, through the mixing of flora and fauna that
    had long been isolated geographically. Invading species are present
    almost everywhere. On many islands, more than half of the plant
    species are non-indigenous, and in many continental areas the figure
    is more than 20 percent (Vitousek 1997).

-   Approximately 10 percent of the 20,000 species of plants in the U.S.
    were expected to become extinct between 1985 and 2000 (Farnsworth
    and Soejarto 1985). The potential economic impact of this reduction
    due to the loss of pharmaceutical opportunities exceeds \$3 billion.
    The loss of ecological goods and services is priceless.

-   Globally, changes in land cover have affected the carbon cycle and
    have lead to warming conditions. In an analysis of land use change
    impacts on carbon sources and sinks in the United States, changes in
    land use released about 25 Pg C to the atmosphere over the period
    1700-1990, largely from the conversion of forests to agricultural
    lands and from cultivation of prairie soils (Houghton et al. 1999).

-   A study of the impacts of conterminous U.S. land cover change from
    pre-settlement to the present on the Nation's climate found
    differences in vegetation parameters, resulting from the change from
    natural to modified vegetation (Copeland et al. 1996). The
    differences between pre-settlement and contemporary cover resulted
    in changes in surface roughness, albedo, and leaf area. As a result,
    mean daily temperature increased for the conterminous U.S. by .05
    ºK. Locally, temperature changes were in excess of 1-2 ºK warmer or
    cooler, though warming dominated. Precipitation rates generally
    increased throughout the U.S., by about 5 percent (.09 mm/day). The
    location of changes tended to occur along the ecotones.

Whether ecosystem changes are caused by natural events (e.g., windstorms
and landslides), or by human activity (e.g., deforestation or pollution
of streams), ecosystems are undergoing change. While it is important to
consider both natural and anthropogenic change, we must not lose sight
that that human-induced changes to ecosystems are more extensive and
rapid than the slower evolutionary changes on ecosystem capacity and
character caused by climatic or geologic changes (Bryce, et al. 1999).

## **The Scientific Call for Ecosystem Health, Sustainability, and Land Surface Change Research**

There is a clear scientific call for research on ecosystem health,
sustainability, and land surface change. For example, the U.S. Global
Change Research Program (USGCRP) has elevated both [land use and land
cover dynamics]{.underline} and [terrestrial and aquatic ecosystem
functioning]{.underline} to focus areas for the new ten-year plan for
USGCRP-sponsored global environmental change research. In parallel, the
International Geosphere-Biosphere Program of the International Congress
of Scientific Unions has established core research programs for Global
Change and Terrestrial Ecology (Steffan et al. 1992) and Land Use and
Cover Change (Turner et al. 1995).

Perhaps the clearest call for research on ecosystem health and land use
and land cover dynamics resulted from the National Research Council
(NRC) response to a National Science Foundation (NSF) request to
identify the "Grand Challenges in Environmental Sciences" (NRC 2001b).
An interdisciplinary committee was asked to determine the most important
research challenges within the context of environmental sciences
environmental problems. The committee considered what the most
significant research challenges would be during the next 20-30 years and
spelled out eight grand challenges. The three grand challenges that are
especially relevant to ecosystem health, sustainability, and land
surface change are:

-   GRAND CHALLENGE 1: BIOGEOCHEMICAL CYCLES: The challenge is to
    understand how the Earth's major biogeochemical cycles are being
    modified by human activities in order to develop the capacity to
    predict the impact of these human impact at local, regional, and
    global scales.

-   GRAND CHALLENGE 2: BIOLOGICAL DIVERSITY AND ECOSYSTEM FUNCTIONING:
    The challenge is to understand the regulation and functional
    consequences of biological diversity, and to develop strategies for
    sustaining biological diversity and the dependent ecosystem
    functions.

-   GRAND CHALLENGE 7: LAND-USE DYNAMICS: The challenge is to develop a
    comprehensive understanding of changes in land uses and land covers
    that are critical to biogeochemical cycling, ecosystem functioning
    and services, and human welfare.

The committee was also asked to identify a small number of areas of
environmental science that especially deserved an accelerated
implementation. The committee recommended four areas that the NSF,
preferably in cooperation with other federal agencies, can immediately
accelerate research activities. These are [Biological Diversity and
Ecosystem Functioning]{.underline}, [Hydrologic
Forecasting]{.underline}, [Infectious Disease and the
Environment]{.underline}, and [Land-Use Dynamics]{.underline}. The grand
challenges committee estimated that each of the recommended immediate
research investments requires several hundred million dollars over a
10-year period.

Two additional NRC reports provide emphasis and focus for this science
plan. A 1999 NRC report on *Measures of Environmental Performance and
Ecosystem Condition* recommends that a proactive science agenda is
needed so that rather than waiting for environmental disasters, we would
have the means to avoid serious problems (NRC 1999). The report places
significant emphasis on investigations of the complex relationships
between humans and the environment. It concludes that those who measure
the condition of impacted ecosystems often lack information on the
particular human activities that are responsible for changes in
ecosystem conditions. As a result, more emphasis on data collection and
monitoring of both ecosystem processes and land use and land cover
change is called for.

An NRC report titled *Ecological Indicators for the Nation* declares
that largest ecological changes caused by humans result from land use -
e.g., replacing native biological communities with agricultural systems,
changing hydrological and biogeochemical cycles, changing the Earth\'s
surface by creating buildings and transportation corridors, and so on
(NRC 2000). Because these changes affect the ability of ecosystems to
provide the goods and services that society depends on, there is a need
to collect the land cover data needed to provide a rough inventory of
the Nation\'s biological capital and serve as an essential indicator.
Information on land cover also provides a reference point and is needed
to calculate several other indicators, and provides a standard against
which to detect and measure changes (NRC, 2000).

## **Summary Perspectives**

The evidence that land surface change is jeopardizing ecosystem health
and sustainability from local to global scales is powerful.
Consequently, there is a need for the USGS to form a strong science
agenda that leads to an improved and broader understanding of how land
surface change affects ecosystem form and function, and ultimately
ecosystem health and stability. Many scientists and policy makers at all
levels of government are asking how comprehensive long-term stewardship
can be established - especially with foresight, rather than hindsight
(figure 5). The policy and management quest for foresight presents a set
of scientific challenges:

-   How do we monitor the health of the Nation's ecosystems? What are
    the appropriate measurements (indicators)?

-   How do we assess the cumulative effect on ecosystems of past,
    present, and anticipated future human activities (and of other
    "external" factors, such as climate)?

-   How do we assess the future availability of ecosystem benefits?

Books have been written on these topics. It is clear from them that
tools and paradigms are rapidly evolving. But the academic application
of these ideas in small areas such as Long-Term Ecological Research
(LTER) sites does not address the United States share of the \$33
trillion annual harvest of ecosystem benefits. That is the job of USGS
and other science agencies. The leap from typically small-area
assessments of ecosystem state and evolution to national-scale
assessment is daunting. In the next section, we offer a strategy and
list the science questions that collectively comprise the first steps
toward that leap.

# **Science Questions** {#science-questions .unnumbered}

To understand the relationships between land surface change and
ecosystem health and sustainability, we suggest that there are three
integrated science thrusts. These three thrusts contain the core science
questions that must be understand and answered if we are to achieve
ecosystem health and sustainability in the face of ongoing land surface
change. The first two, [Ecosystem Issues]{.underline} and [Land Surface
Change Issues]{.underline}, provide the basic foundations for
understanding of ecosystem form, function, processes, and condition,
along with perturbing landscape dynamics. In essence, they are the
baseline science issues that characterize historical and contemporary
conditions and serve as the starting point for looking at health and
sustainability of ecosystems.

The third research thrust includes the [Integration, Assessment, and
Monitoring Issues]{.underline} which departs from basic research into
applied studies and possibly operational assessment and monitoring. In
this group, ecosystems operations and land surface change are considered
together and issues associated with data integration, scaling of
processes, and large area assessment strategies, are used to determine
the status and trends of ecosystems. The research questions included in
this section are critical to the USGS goal for periodic assessments of
the Status and Trends of our Nation's biological and geographical
resources.

## **Ecosystems Issues**

Ecosystems have intrinsic values and provide essential goods and
services. These can be summarized as the range of functions that are
utilized by humans. The goal of resource management agencies is
sustainability of their resources. Making sustainable use of the
intrinsic values of ecosystems and the benefits they provide requires a
mechanistic understanding of ecosystem function and structure and the
important drivers that constrain ecosystem processes.

The Ecological Society of America has produced two reports that discuss
incorporating ecological principles into the land-use decision making
process and ecosystem management. Christensen et al. (1996) focused on
application of ecological principles in managing ecological systems.
Dale et al. (2000) offered a set of ecological principles relevant for
making decisions regarding human activities that result in changes of
land use from one type to another. A critical element to both reports is
the application of sound ecological science to resource management to
promote long-term sustainability of ecosystems, the continued delivery
of essential goods and services to society, and the conservation of
important trust resources.

The USGS should play an instrumental role in developing a more
comprehensive understanding of multi-scale ecosystem processes and the
consequences of changing land-use and land-cover on ecosystems by
promoting: experiments, long-term studies, and the development of
improved tools to address critical questions in ecosystem science
(figure 5). The science questions listed here provide a framework for an
improved understanding of basic ecosystem concepts and processes, and
will illuminated the key ecosystem drivers and responses to stress.
Collectively, these factors serve as a basis for determining the
ecological consequences of land surface change through a functional
understanding of how land conversion and water diversion affect
ecological processes.

*How should we define ecosystems?*

[Justification]{.underline}: The most widely used conceptual model of
ecosystems depicts them as sums of loosely related and often quite
abstract components (organisms, populations, communities, communities
plus nonliving components), rather than as integrated biogeochemical
systems with recognizable structural and functional properties. The
components actually represent independent lines of scientific inquiry,
each with its own set of theoretical and analytical approaches.
Conceptual models that address ecosystems, as functional wholes are
rare. Hence, there is no clear consensus as to how to characterize the
health of an ecosystem or assess whole-system responses to environmental
change.

The USGS should play a role in developing a new conceptual model of
ecosystems that allows for more useful identification and quantification
of ecosystem properties and responses to external stresses. Ideally,
this new conceptual model will make use of the hierarchical structure
common to all complex natural systems (Allen and Starr, 1982). A
hierarchical model of an ecosystem might consist of all relevant
ecosystem processes arrayed according to their frequencies of
occurrence, which would range from picoseconds to centuries (see figure
6, from Schindler et al., 1980). The ecosystem exists at every level of
this frequency hierarchy and may be studied at any level by specifying
an appropriate frequency window for sampling or observation (Schindler
et al., 1980).

The USGS also should be involved in elucidating the importance of
individual organisms and populations of organisms in determining
ecosystem responses to external stresses. Recent experimental work in
this area has shown that the temporal stability of some ecosystem
processes in response to environmental change is related to the number
of species present, but there remains much work to be done in extending
these relations across ecosystem types and processes (Hector et al.,
1999; Griffiths et al., 2000; Loreau et al., 2001).

[Action]{.underline}: Develop new conceptual models of ecosystems that
explicitly recognize the hierarchical organization of ecosystem
properties and directly relate ecosystem components to observable
macroscopic system behaviors; pursue understanding of the role of
biodiversity in determining ecosystem responses to external
environmental change.

*What is the relationship between biological diversity and ecosystem
structure and function?*

[Justification]{.underline}: The number, relative abundance, identity,
and interactions of species all affect ecosystem processes. Species are
most likely to have strong ecosystem effects when they alter interactive
controls that affect the drivers that directly regulate ecosystem
processes. Chapin et al. 2000 and Charney et al. 1977 documented how
changes in vegetation could affect regional climates. Changes in species
presence can alter trophic dynamics and have large ecosystem impacts.
The addition or removal of a fish species from lakes has large effects
that cascade up or down food chains (Carpenter et al. 1992). Changes in
the abundance of top predatory fishes may change phytoplankton
composition and alter the productivity of lake systems. Removal of
mammalian herbivores can lead to an increase of woody plants in savannas
and affects the productivity of the plant communities they graze
(Owen-Smith 1988, McNaughton 1979).

There are many uncertainties regarding the functional importance of
species to ecosystem structure and function and the impact of changing
land-use on this relationship. A better understanding of fundamental
ecological processes and the interaction of biotic and abiotic factors
can improve the success rate and effectiveness of ecological
restorations. The introduction of exotic species in both natural and
managed systems has negative consequences and illustrates the number and
kinds of species present in an ecosystem are not alone sufficient to
predict the impacts to ecosystem functioning. Most species management
decisions often do not include a realization of the larger scale
implications of those decisions. Acknowledgement of the significance of
biological diversity is critical for management decisions.

[Actions]{.underline}: Initiate empirical studies that advance our
understanding of the role of individual species in ecosystem processes.
Facilitate basic research on the interaction between community level
processes and ecosystem function.

*What is the role of spatial heterogeneity within and among ecosystems
to the functioning of individual ecosystems and of entire regions?*

[Justification]{.underline}: Landscapes are mosaics of patches that
differ in ecologically important properties. Some patches are more
important than size alone would suggest. Beavers create small ponds in
the boreal landscape that result in increased contributions of methane
emissions in the global carbon cycle (Roulet et al. 1977). Species
conservation plans often depend on the movement of organisms between
patches utilizing habitat corridors (Fahrig and Merriam 1985). Habitat
connectivity can constrain the spatial distribution of species or
enhance it. Landscape pattern also influences the transfer of materials
among ecosystems. The loss of riparian habitat can increase the loading
of sediments and nutrients to streams (Correll 1997) and strongly affect
the maintenance of desirable water quality. Local ecological structure
may be explained by attributes of the surrounding landscape as well as
characteristics of individual patches. At some critical point, habitat
fragmentation results in populations of greater risk to local extinction
because of reduced population sizes and impediments to migration.

A landscape scale perspective is needed because the structure and
function of a particular ecosystem is influenced heavily by the nature
of the landscape that surrounds it (figure 7). Ecosystems do not exist
as isolated units on the landscape but interact through the movement of
materials, organisms, and disturbances from one patch to the other. An
emphasis on understanding the role of landscape heterogeneity is
critical because it helps determine the regional consequences of
processes occurring in individual ecosystems. Although some ecosystem
processes can be understood at larger spatial scales without considering
landscape heterogeneity, other processes, such as vegetation response to
changing climate can only be understood by using spatially explicit
models that incorporate species migration and the spread of disturbance
among patches (Mladenoff and Baker 1999).

[Actions]{.underline}: We need to develop the appropriate remote sensing
and Geographic Information System (GIS) technologies that permit
examination of spatial patterns at appropriate spatial scales.

*How do the type, intensity, and duration of disturbance affect the
characteristics of ecosystems?*

[Justification]{.underline}: Ecosystem dynamics occur against a backdrop
of continuous change. The patterns found on any landscape are the
product of natural disturbances (Heinselman 1973). The effects of
disturbance are controlled by their intensity, duration, frequency,
timing, and spatial impacts (Pickett and White 1985). Because
disturbance is a natural component of all ecosystems, the successional
changes in ecosystem processes after disturbance are important in
understanding regional patterns of ecosystem dynamics. Disturbances lead
to mosaics of successional patches across the landscape with important
consequences for ecosystem structure and function (Foster 1988, Myers
1985). Certainly a better understanding of the properties of disturbance
regimes will help us understand the ecological consequences of
disturbance. The roles of large-scale infrequent disturbances on
ecosystems are fundamentally different than the impact of small-scale
frequent disturbances (Turner and Dale 1988). The formation of single
tree gaps is the primary source of canopy turnover in temperate forests
leading to the maintenance of the productivity and nutrient dynamics of
the entire forest. But increasingly, we are recognizing the role of
catastrophic disturbances such as hurricanes (Guntenspergen et al. 1995)
or human-induced changes in affecting ecosystem structure.

[Actions]{.underline}: Experimental perturbations of the appropriate
scale, intensity, and type are essential for the evaluation and
comparison of alternative management strategies to disturbance. New
generations of ecological models must be developed that analyze the
dynamics of ecosystems at landscape scales.

*What are the time scales of important ecological processes?*

[Justification]{.underline}: Ecosystem dynamics are a product of factors
operating at many temporal scales. Rates of ecosystem processes are
limited by the temporal pattern of key driving factors. Many wetland
processes are mediated by the organic matter content of the soil that
has accumulated over long periods of time (Mitsch and Gosselink 2000).
Restoration of key wetland processes is often not feasible because the
time interval since restoration is not sufficient to accumulate organic
matter (Kusler and Kentula 1990). Ecosystems respond to changes that
occur over different time scales but measurements of ecological
processes are generally made over shorter time periods. Process based
models are an important tool for making projections of the state of
ecosystems over longer time intervals than can be measured directly.
Pastor and Post (1986) developed a model LINKAGES that examined the
impact of changing climate and succession on forest carbon and nitrogen
cycles.

[Actions]{.underline}: Long-term multidisciplinary studies and the
development of new techniques to reconstruct past communities and
landscapes will be necessary to understand the appropriate time scales
for ecosystem response.

*What are the mechanisms linking processes operating at different
temporal scales within ecosystems? What are appropriate scaling
strategies for investigating these processes?*

[Justification]{.underline}: Explicit recognition of the temporal scales
of ecosystem behavior carries with it the need for understanding how the
various subsystems interact to produce observable behaviors. This is an
area of active research in which the USGS could make a significant
contribution. New approaches are needed for relating ecosystem processes
operating at different temporal scales to whole-system responses and to
temporal patterns of environmental change. Recently developed
theoretical models (Enquist and Niklas, 2001) have indicated that
resource-distribution networks in natural systems ranging from
individual plants to landscapes develop in similar ways that can be
predicted using fractal geometry. The USGS should play a role in
expanding and testing these ideas.

[Action]{.underline}: Investigate relations between ecosystem components
and whole-system behaviors; elucidate rules of ecosystem organization
and show how organization is related to function.

*What allows ecosystems and ecosystem processes to persist in the face
of perturbations?*

[Justification]{.underline}: Ecosystems respond to multiple forcing
functions. An ecosystem's resilience is determined by the extent to
which it maintains its properties in the face of change to those forcing
functions. The response of systems to alterations is also a function of
other processes that operate at different scales within the landscape to
mitigate the effects of disturbance. When these factors are largely
intact, watersheds and their component ecosystems can withstand
perturbations. For instance, the resilience and sustainability of lakes
depends on a range of control processes (including the role of top
predators in trophic dynamics, absorption of nutrients by macrophytes,
and the filtration effects of riparian vegetation) that can mitigate the
effects of disturbance (Carpenter and Cottingham 1997).

[Actions]{.underline}: Research programs must be initiated that
explicitly address how different stresses affect ecosystem functions
within and among systems. We need to compare how different ecosystems
respond to similar stresses. Long-term studies that establish baseline
variability for ecosystems and long-term research sites present the best
opportunities to address this question.

*What measures of ecosystem behavior might best be used to track
responses to ecosystem stresses?*

[Justification]{.underline}: The USGS has long been recognized as a
leader in the development of methods for long-term monitoring and
assessment of natural resources. The opportunity now exists to extend
this expertise to monitoring ecosystem processes that indicate how these
systems are responding to environmental change. Research is needed to
identify which processes best reflect ecosystem response. Processes
operating over a wide range of temporal and spatial scales will have to
be investigated, and new methods for real-time monitoring at appropriate
scales developed.

[Action]{.underline}: Identify ecosystem processes that indicate
whole-system responses to stress; investigate relations between
whole-systems responses and ecosystem components; develop methods for
real-time monitoring of ecosystem behavior.

*How can we predict ecosystem responses to external stresses?*

[Justification]{.underline}: Ecosystems are affected by natural and
human-induced stresses, many of which are related to land-surface
change. Development of the landscape alters drainage patterns, reduces
biodiversity, and may increase fluxes of sediment and other contaminants
to receiving areas such as lakes and reservoirs (Vorosmarty and Sahgian,
2000). New modeling approaches are needed that will enable natural
resource managers to predict the effects of land-surface change on
ecosystem structure and function, and to quantify potential losses of
essential ecosystem services. Related to this need is the ability to
assess ecosystem vulnerability to external stresses, both natural and
human-induced, and in both prehistoric and contemporary timeframes. As
important to understanding human impacts is the understanding of how the
present system evolved and what the evolutionary paths were. The USGS is
well positioned to develop and apply predictive ecosystem models at a
variety of spatial and temporal scales. The USGS should use this
capability to design decision-support systems that include criteria for
ecosystem health and sustainability.

[Action]{.underline}: (1) Reconstruct Holocene climate and ecology,
identifying rates and trends and the current status of ecosystems within
the long-term picture. (2) Develop integrated models for predicting
ecosystem responses to land-surface change; provide decision-support
systems for predicting ecosystem vulnerability to environmental
disturbance.

## **Land Surface Change**

Land surface change research must focus on all forces and factors that
perturb land cover (i.e., land use change, natural disturbances) because
cover represents the form of ecosystems and links directly to available
goods and services. While contemporary change has been significantly
accelerated and change by human activities, natural elements (e.g.,
wind, water, severe storms, flooding, insects, etc.) continue to be
forces of modification. It is clear that we must have a much better
understanding of the three pillars of land surface change research --
the rates, causes, and consequences of change.

The first step toward an improved scientific understanding of change is
to understand the past, current, and future land use and land cover
patterns and characteristics. This understanding must involve the
reconstruction of past natural vegetation characteristics, the
establishment of post-Industrial Revolution land use change, and the
ability to predict future land use scenarios. Most contemporary
landscapes are the mosaic of natural remnants of natural vegetation, and
present and former patterns of land use and economic activity.

The consequences of land cover change are geographically variable, and
depend on such factors as the characteristics of the pre- and
post-disturbance land cover, the specific conversion or modification
process, geographic location, spatial and temporal distribution, and
whether one is considering the impact of the change on biogeochemical
cycling, on species composition and abundance, or on the climate system.
It is important to recognize the feedback between first generation
consequences and time-lagged secondary consequences affecting land use
and land cover.

The following questions form the rates, causes, and consequences
research needed to understand the role of land surface change and
ecosystem health and sustainability.

*How have the patterns and characteristics of natural vegetation evolved
over the past 10,000 years?*

[Justification]{.underline}: In order for ecologists to build a
comprehensive framework for understanding the evolution and dynamics of
species and communities, the empirical record of past vegetation and
environmental change must be defined (Delcourt and Delcourt 1983). The
biotic and abiotic characteristics of the Earth\'s surface have not been
static. Rather, the Earth is a dynamic system and knowledge about
changes to the Earth\'s surface and the underlying processes that induce
them are an important part of understanding natural ecosystems and the
thresholds of change that affect the provision of ecological goods and
services. The length of the historical record of reconstructing
vegetation patterns and characteristics is an open research question,
but we know it is important to understand North American vegetation from
the end of the ice age to modern times. With this knowledge, we can
begin to understand how our ecosystems have evolved to their current
status.

[Actions]{.underline}: Reconstruct the patterns of natural vegetation
for various climatic conditions that occurred periodically over the past
10,000 years. Through an examination of fossil, pollen, and other
records, there must be a spatially explicit mapping of the primary
natural vegetation patterns, ecosystem extents, and natural disturbance
regimes.

*How has land cover been changed by human use over the past 300 years?*

[Justification]{.underline}: Human modification of the Earth accelerated
dramatically at the onset of the Industrial Revolution in the 18^th^
Century. The Industrial Revolution started a long transition from an
agrarian to urban society. It also signaled the demographic transition
in which birth rates began to exceed death rates. As a result, human
population began to rise at an unprecedented rate and the economic
activity of the expanding population had greater demands for land to
support their diversified economies. This period also coincides with
European settlement of the Americas. While Native American land uses
modified the natural environment, the sheer number of European settlers
started a transformation of ecosystems that continues today.

The spatial and temporal pulses of change that have occurred over the
past 300 years are understood in only very general terms. Regional and
global-level changes of most land covers and uses, including such
essential categories as forest and grassland cover, agricultural uses,
and urban and suburban settlement, are still poorly documented (figure
8; National Research Council 2001b). An improved understanding of land
use dynamics is critical to understanding the contemporary modifications
of ecosystems and to develop the baseline understanding needed to
project and mitigate future impacts to that an appropriate level of
sustainable goods and services can be attained (International Geosphere
Biosphere Programme, 1993).

[Actions]{.underline}: (1) Develop a spatially explicit land use history
of the U.S. from pre-European settlement to the present. (2) Conduct
more detailed case histories that provide a means to understand the
detailed mechanistic components of land use and land cover change.

*Based on the past, how will changes in land use affect land cover in
the next 50 to 100 years?*

[Justification]{.underline}: In order to anticipate threats to ecosystem
health and sustainability, it is essential that some level of predictive
capacity be developed that permits the identification of ecosystems or
ecosystem remnants at risk because of potential land use change. The
development of a framework for global models should consider the
long-term synoptic rates and patterns of land use and land cover change,
analyses of specific local case studies in selected regions; and the
impacts of different driving forces in different regions of the country.
It is likely that several different types of forecasting models and
strategies will be needed. This suite of models should enable dealing
with the land surface characteristics, driving forces of change, and
scenarios of change that are appropriate for different parts of the
country.

[Actions]{.underline}: (1) Develop predictive models for forecasting
land use changes and subsequent patterns under various scenarios. (2)
Based on past rates and causes of change, determine a series of
realistic scenarios of change based on logical future states.

*What are the major natural and human causes of land use change in
different geographical and historical consequences?*

[Justification]{.underline}: Historically, the macro driving forces of
settlement and the corresponding land use and land cover change in this
country have been directly related to advances in transportation
technology (Borchert 1967). The contemporary forces are more diverse,
but relate to combinations of factors including population, affluence,
technology, political economy, political structure, attitudes, and
values (figure 9; International Geosphere Biosphere Programme, 1993).
Any given change in any given locality may be triggered by local forces
(e.g., a family decides to harvest timber on woodlot to pay debts),
global forces (e.g., high energy costs have increased debt load,
requiring quick source of income to retire debt), or some combination of
the above. Driving forces commonly operate in combinations, and these
forces and combinations of forces vary from place to place and from time
to time. Thus, the determination of the driving forces of change must be
made at multiple spatial and temporal scales and in union with studies
of actual land cover transformations.

[Actions]{.underline}: (1) Develop a framework for determining the
local, regional, and global driving forces of land use and land cover
change. (2) Document the major driving forces of U.S. land use change
for the past 100 years. (3) Identify episodes of combined driving forces
that had specific geographic and temporal signatures.

*How do human-induced land use and land cover changes affect ecosystem
form and function?*

[Justification]{.underline}: Human actions strongly influence changes in
the Earth's biogeochemical cycles, climate, and overall levels of
biodiversity with potentially devastating effects. Conversion of
forested land to agriculture have redistributed carbon from plant, soil,
and mineral pools into the atmosphere, where greatly increased CO~2~ has
the potential to alter climate, affect the photosynthetic efficiency of
vegetation, and change large-scale ecosystem dynamics. Ecosystems
consequences vary widely from place to place and over time for many
reasons, and nationally and globally averaged assessment information
relates only weakly to those unique situations (National Research
Council, 2001b). A basic question involves determining which regional
land use practices reflect the properties of the most common ecosystems.
To understand the regional impacts of land use on ecosystem health, it
is clearly necessary to know and compare the properties of local and
regional ecoregional characteristics (Chapin et al. 1998). There is
sometimes an obvious connection between the sequence of land use change,
land cover alteration, and ecosystem characteristics, such as the
clearing of forests, the increase in erosion and sedimentation of
streams, and a modification of stream diversity. In other cases, the
changes may be less direct. For example, when a natural landscape is
fragmented, overall community diversity may stay the same or even
increase, yet the integrity of the community has been compromised with
an invasion of weedy species and the loss of species unable to persist
in small, isolated patches of habitat (Noss 1990). It is very important
to recognize that the impacts on ecosystem form and function can vary
significantly over time and space. For example, areas with high levels
of species endemism may not be able to absorb the same modifications as
ecosystems that do not host high levels of endemic species (Myers et al.
2000). Regardless of ecosystem sensitivity, the major cause of
biodiversity loss is primarily the way land use alters habitat. Yet the
ability to describe and forecast the impact of specific human actions
upon biodiversity is not well developed and practical techniques for
conducting such analyses are needed (McKendry and Machlis 1993).

[Actions]{.underline}: (1) Document the primary consequences of land use
and land cover change across the United States on ecosystem form and
function for the past 300 years. (2) Conduct an assessment of the
Nation's ecosystems to determine if the current land use activities
conducive to sustaining pre-defined ecosystem health. The three
Overarching Questions (see Goals section) are the logical target states
for this assessment. (3) Develop a predictive consequences model which
provides the means to estimate the consequences of land use and land
cover change on ecosystem form and function, given the local
characteristics of land use and land cover, and ecosystem status.

*What are the feedbacks between land use/cover change on climate and
biogeochemistry?*

[Justification]{.underline}: Six elements (carbon, oxygen, hydrogen,
nitrogen, sulfur, and phosphorus) represent 95 percent of the biospheric
mass on the Earth. The cycling of these six biogeochemical elements
through the Earth system constitutes the biogeochemical cycles. It is
clear that the rapid rises in element concentrations are being driven by
global changes in the Earths biogeochemical cycles. What is less clear
is how long these changes in biogeochemical cycles will continue, what
effects they are having on the climate system, and what the positive and
negative feedbacks are on land use, land cover, and ecosystems are and
whether the feedback accelerates or reduces these effects (National
Research Council, 2001b). The growing appreciation of the role of past
changes in land use and management for terrestrial sources and sinks of
carbon should stimulate a rethinking of the terrestrial carbon cycle. A
substantial carbon source from forest clearing and a subsequent sink
from land management have broad implications. Future research on the
terrestrial sink may need to focus as sharply on the history of past
management as on ecosystem responses to future changes in climate and
atmospheric composition. In experimental studies on the carbon cycle,
the interaction of global changes with land management should receive
the same priority as the responses of natural ecosystems (Field and Fung
1999).

[Action]{.underline}: Determine the affects of changing biogeochemistry
(i.e., nutrient enrichment) and climate (i.e., altered temperature and
precipitation patterns) on land use and land management practices, and
ultimately on ecosystem health under different future states scenarios
(i.e., doubling of CO~2~).

## **Integration, Assessment, and Monitoring**

Data integration, assessment, and monitoring strategies will be needed
to determine the impacts of land surface change on ecosystem health and
sustainability. The following research questions are important for
gaining a detailed understanding of the fundamental characteristics of
ecosystem health, but are also important for ensuring that the Nation\'s
natural resources at the ecosystem scale and essential ecosystem
services are being protected from environmental degradation related to
land surface change.

*How can we account for ecosystem processes and responses to
land-surface changes that occur over temporal scales of years to decades
to centuries?*

[Justification]{.underline}: The processes that allow terrestrial
ecosystems to respond to environmental changes operate over time scales
ranging from years to centuries. Research at the Park Grass ecological
research station in Harpenden, United Kingdom, for example, has shown
that grasslands can take up to 60 years to recover from changes in
nutrient loading rates (Tilman et al., 1994). Long-term studies are
essential if we are to fully understand the responses of ecosystems to
stresses such as global warming. In addition, there is a need for better
understanding of the ways in which ecosystems interact with
environmental changes occurring a multiple frequencies.

The USGS has the organizational structure, as well as the experience in
developing and maintaining spatial and relational databases, for
conducting long-term ecosystem studies that link monitoring and
investigative approaches and results. The National Research Council
(2001), in a detailed evaluation of future roles and research
opportunities for the USGS, has suggested that research projects
conducted over periods of 5 to 10 years provide the necessary time
horizon for producing significant results. These projects would
compliment the National Science Foundation\'s very successful Long Term
Ecosystem Research (LTER) network and the BRD\'s Long-Term Resource
Monitoring Program. It should also be possible to use existing USGS data
sets to evaluate hypotheses regarding ecosystem responses to land
surface change. For example, Knapp and Smith (2001) recently used data
on above ground net primary production from 11 Long Term Ecological
Research sites across North America to evaluate the responses of
terrestrial ecosystems to fluctuations in rainfall, and Pearl et al.
(2001) examined the impact of hurricanes on coastal ecosystems using
USGS flooding and streamflow data (figure 10).

[Action]{.underline}: Provide mechanisms for USGS ecologists to design
and conduct multi-year investigations of ecosystem responses to
environmental change.

*What methodological advances are needed to monitor ecosystem structure
and function, and land-surface change in a spatially explicit fashion?*

[Justification]{.underline}: Monitoring will require measurement and
observation from *in situ* to synoptic scales of a significant number of
variables that relate to land surface change (i.e., land cover type,
canopy density, imperviousness) and to ecosystem structure and function
(i.e., physiognomic variables including canopy height, density, and leaf
area, net primary production, carbon flux). Field measures will be
needed to establish the baseline conditions of specific ecosystems.
Synoptic monitoring, and extrapolation of *in situ* measurements can use
remotely sensed data. Because remote sensing systems can typically
acquire large amounts of data that can be spatially rectified and
processed, characterizing the temporal dynamics of large areas may be
more practical with remote sensing than through traditional field
approaches (Quattrochi and Pelletier, 1990). Monitoring change (e.g.,
land use change, deforestation) is both one of the most important yet
difficult contributions of remote sensing technology to studies of
ecological change (Roughgarden, et al., 1991). The transition from
conventional mapping studies to a more analytical endeavor based on
theory and modeling will be difficult, but it should be aided by growing
attention to the role of land surface change and ecosystem processes in
and by development of fields such as landscape ecology and of tools such
as geographic information systems (Riebsame et al., 1994).

[Action]{.underline}:

\(1\) What are the fundamental spatial and temporal scales upon which to
monitor ecosystems (2) What spatial frameworks and overall monitoring
design should be implemented to sample ecosystems; and (3) What
ecosystem and land use and cover variables should be measured and how
should they be captured?

*How can we put site-based studies of ecosystem processes into a spatial
context so that we can extrapolate the results of those studies over
larger geographic areas (drainage basins, landscapes, ecoregions)?*

[Justification]{.underline}: The USGS conducts many investigations of
specific ecosystems, often addressing a particular question or need,
with the expectation that the completed work will be transferable to
other sites in the region or the Nation. Ecosystem and land surface
change studies cannot be handled at a single scale of observation. An
understanding of how processes operate at various spatial scales and how
they can be linked across scales becomes a primary goal when
investigating these complex phenomena (Marceau, 1999). What is needed is
research on strategies and procedures for ensuring that the results of
these site-based investigations can be used to help answer questions of
national importance. The National Research Council\'s (2001)
recommendation that the USGS place more emphasis on multidisciplinary,
integrative projects that address environmental issues of a national
scale should be implemented, but the agency will still be involved with
a variety of site-specific investigations and assessments. The USGS
should be committed to providing National leadership in integrating and
extending the results of ecosystem research at all levels.

[Action]{.underline}: (1) Develop a series of hypotheses that link site
to landscape processes and inter-ecosystem processes into larger
framework. (2) Establish a National framework suitable for coordinating
and integrating site-based investigations of ecosystems so that results
and conclusions can be evaluated and extended to other systems at the
same or greater spatial scales.

*What is the appropriate design and implementation strategy for a
National Environmental/Ecosystems Assessment Program?*

[Justification]{.underline}: The payoff of the basic research listed in
this science strategy is the establishment of an operational program for
monitoring the health and sustainability of the Nation's ecosystems
(figure 11). Through the operation of a near real-time ecosystem status
and trends program, anticipation and management of problems will become
more feasible and the health of ecosystems more likely. However, it
important to recognize that a universal system for ecosystem analysis
will only develop if the conceptual and theoretical advances expressed
in this document are addressed first.

[Action]{.underline}: Design and test a near real-time system for the
national-scale assessment of ecosystem status and trends.

# **Projected Infrastructure Needs** {#projected-infrastructure-needs-1 .unnumbered}

The infrastructure requirements associated with this initiative are
potentially vast. We are not only proposing an emphasis on basic
questions in ecosystem science and understanding the drivers of land use
change but promoting an understanding of how these changes affect
ecosystem condition and the goods and services ecosystems provide
humanity. And finally, we are emphasizing continued developed of the
science that underlies and will be used in developing periodic
assessments of the condition of the Nation's ecosystems. The complexity
of this initiative reflects the complexity of integrated science in
general. The science that we describe engages multiple disciplines in
the physical, biological, and social sciences. And to ensure success
there is a need:

-   To develop new skills, either through new hires or through training
    programs.

-   For increased field experiments, and greater use of spatial
    technologies (i.e., remote sensing, GIS, global positioning
    systems).

However, the most important step that needs to be taken is to establish
mechanisms that put together teams of ecosystem scientists and
geographers together to address the critical questions associated with
ecosystem health, sustainability, and land surface change.

## **Organization**

Clearly, we cannot undertake the science of ecosystem and land surface
change without better integration of the scientific expertise of
existing staff. In order to develop an integrated initiative of
ecosystem health, sustainability, and land surface change, there is a
need to immediately institute a socialization process where selected
scientists in the various disciplines can periodically interact and
learn from each other and to identify research priorities and to develop
the specific implementation strategies implied in this science strategy.

The challenge involves the selection of the integration strategy. We
suggest that this science strategy is uniquely suited to regional
implementation in which a series of ecosystems teams are established
that conduct the research in integrated teams of ecosystems, land
surface change, and integration, assessment, and monitoring scientists.
Because ecosystem status and geographic character will have significant
impacts, the science strategy should be implemented in regions with
differing ecosystem health and land use histories. That said, [it is
essential that the ecosystem health, sustainability, and land surface
change science initiative be designed as a national
investigation]{.underline}. Large-area studies are more challenging but
lead to meaningful conclusions regarding the connections between human
and environmental systems. There is an overriding need for synoptic
analyses of the linkages between land surface change causes and
consequences, and of the corresponding variable impacts on different
ecosystems. Therefore, it is mandatory that this activity have a strong
lead center for research design, scientific oversight, and integration,
assessment, and monitoring studies.

## **Staffing, Skills, and Strategies**

This research will require scientists that have, according to Gober, new
\"habits of the mind,\" which include training and experience in broader
ways of thinking (2000). The new intellectual habits must include both
specialized analytical research capabilities and the ability for broader
integrative research.

The unique niche of the USGS is our ability to conduct studies at
unprecedented spatial and temporal scales. Scales have a way of masking
complexity and often suppress the unexpected connections. Thus, the USGS
will need to seek scientists that can span scales and operate both
locally and nationally. The research we have proposed will place greater
emphasis on the integration of observations from local to National and
global scales. Staff with expertise in up- and downscaling methods are
not available in the USGS. Furthermore, staff with modeling experience
are also uncommon but are vital to the success of this research.

The development of interdisciplinary models, both conceptual and
computational, will be a core ingredient of the program. The National
Research Council's Committee on Future Roles, Challenges, and
Opportunities for the U.S. Geological Survey has emphatically stated the
need for USGS to develop such models (NRC, 2001). Such development
requires skills that are in short supply in USGS, such as systems
analysis, operations analysis, and object-oriented design and
programming. Staff with expertise in understanding socio-economic
systems will be needed to study the driving forces of land surface
change. It will also be important to organize teams of regional
geographers that have the breadth and depth to synthesize the complex
interactions between the natural and human landscape. Table 2 summarizes
the expected staffing needs, levels, and special skills.

There are going to be many very specialized research tasks that need to
be addressed as we pursue the overall science strategy goal. Rather than
hire staff for highly unique and short-term research tasks, we recommend
that linkages to key universities be established and collaborative
arrangements be use engage the exceptional talents within academia.

## **Facilities**

Ecosystems and the human activities that affect them are the primary
laboratories for this science initiative. It is important to have
opportunities to observe and test hypotheses associated with ecosystem
structure and function and responses to external perturbations. A first
step in establishing a national research capability is to develop
long-term study sites and to join with existing networks of long-term
sites. These will be particularly valuable if they represent the
continuum of disturbances (near-pristine to heavily modified) and
therefore can provide insights into the overarching questions presented
in earlier. Relationships with LTER sites will also be valuable for some
aspects of this research. It is important, however, to investigate both
small, localized ecosystem components and larger ecosystems. Continued
commitment to the USGS Place Based Ecosystems Program and increased
connections to the existing network of LTER sites should be emphasized.

It would be particularly fortuitous if there were opportunities to study
large experimental perturbations. Ideally, we need to be able to do
large scale experimental perturbations (i.e., watershed or small
ecoregion scale) to better understand the response of ecosystems.
Developing cooperative work with other federal agencies that own and
manage lands such as the National Wildlife Refuge System, the National
Park System, can facilitate this.

## **Long-Term Datasets**

The foundation of USGS is the collection and maintenance of long-term
environmental datasets. We are able to conduct research at unprecedented
spatial and temporal scales only because of the collection of long-term
national data sets. Our tradition for long-term data collection is
stronger for hydrological, geological, and cartographic data than it is
for ecological (i.e., biological and land use and land cover change
databases). Unfortunately, the paucity of long-term ecological datasets
limits our current -- and potentially future -- ability to understand
the relationships between landscape pattern, and status and trends of
ecological resources (Jones et al., 1995).

The NRC study on future roles of the USGS determined that the
development and availability of long-term monitoring data is especially
important in the biological sciences, since USGS is one of the few
entities that has the -capacity to carry out this work over long periods
(NRC, 2001a). The NRC report focused on the need for trend data for
species groups or ecosystems. In addition, we also recognize that other
long-term national databases relating to ecosystem structure and
function and land surface change are also needed. Table 3 summarizes
some key datasets that are needed during the course of this research.

We recognize that data are fundamental to the development of knowledge.
We also recognize that for data and information to be valuable to
non-scientists, and particularly to managers and other decision makers,
research must be conducted not only to develop methods to make data and
information more accessible, but also to make it more understandable and
easy to use, and to give a clear indication of the reliability of the
analysis conducted with the data (Kelmelis, 1993). That means that the
research proposed as part of the Future Science Direction on
Environmental Information Science is an important contributor to this
strategy.

## **Complementary Programs**

The USGS has existing programs that can be used as a solid foundation
for the implementation of this research initiative. The biological
discipline has considerable expertise in understanding ecosystem trends
through such means as the recent *Status and Trends of the Nation's
Biological Resources* and the development of the National Biological
Information Infrastructure, a distributed database for biological
information from a variety of sources. The Ecosystem Program (e.g.
Chesapeake Bay and South Florida Place Based Studies Programs) strives
to integrate Survey expertise in common geographic settings. The
Geographic Analysis & Monitoring Program undertakes topical and
long-term studies of the land use and disturbance histories of the U.S.
and produces reports on the status and trends in our Nation\'s land
surface every five years. The program quantifies rates of landscape
change, identifies key driving forces, and forecasts future trends.

The USGS is poised to work closely with other federal agencies,
non-governmental organizations, and international bodies who are also
working to develop methodologies to understand the condition of
ecosystems. EPA's Environmental Monitoring and Assessment Program
(EMAP---<http://www.epa.gov/emap>) and related Regional EMAP
(REMAP---<http://www.epa.gov/emap/html/remap/index.html>) program
support research to develop indicators and monitoring frameworks. EPA is
also home to a number of U.S. Global Change Research Program (USGCRP)
activities <http://www.usgcrp.gov/usgcrp/default.htm>).

NASA's Earth Science Enterprise is home to programs in land cover/land
use change (LCLUC---<http://lcluc.gsfc.nasa.gov/>), and land surface
hydrology (LSHP---<http://lshp.gsfc.nasa.gov/>) which are large in
geographic scope, remote-sensing oriented, and include modeling of land
surface processes.

The USGCRP (<http://www.usgcrp.gov/usgcrp/default.htm>) and its
international counterpart, the International Geosphere-Biosphere Program
(IGBP - <http://www.igbp.kva.se/>), conduct environmental assessments at
national, continental, and global scale. Among the most comprehensive of
these is the U.S. National Assessment, *The Potential Consequences of
Climate Variability and Change*
(<http://www.usgcrp.gov/usgcrp/nacc/default.htm>), which used a
multi-scenario, model-based methodology organized both geographically by
region and topically by sectors.

The Heinz Center for Science, Economics, and the Environment is
developing and testing a comprehensive assessment on the health of the
Nation's ecosystems. The report will focus on the condition and the
goods and services people obtain from ecosystems. However, the report is
envisioned to primarily use data contained within the network of federal
agency databases. The report will identify a set of core measures of
environmental condition and begin the process of periodically reporting
on these measures. A critical aspect of the report is the incorporation
of measures related to the ability of ecosystems to continue to provide
goods and services into the future.

The United Nations Environment Program, UN Development Programme, the
World Resources Institute, and the World Bank have established a
steering committee to develop an international research effort to assess
the condition of the world's biological systems. The proposed Millenium
Ecosystem Initiative will use the findings of natural and social science
research on ecosystem goods and services to help make regional and
global policy and management decisions. The Millenium Ecosystem
Assessment would address the following: (1) Current ecosystem extents,
trends, pressures, conditions, and values (2) A range of plausible
scenarios showing how the quantity and quality of ecosystem goods and
services may change when subjected to varying disturbances, stresses,
and land use change and (3) Identification of policy, institutional, or
technological changes that could improve the management of ecosystems
and maintain their long-term sustainability.

## **Implementation Considerations: Beginning with the End in Mind**

The science that we describe is big science. It engages multiple
disciplines in the physical, biological, and social sciences, and it
considers the entire land area of a large Nation -- and it recognizes
that the nation must be considered in a global context. The soundness of
the scientific approach requires coupling to a large number of local
studies - possibly numbering in the thousands - that validate (or
invalidate) and calibrate the large-area descriptions, and that provide
process knowledge to the national-scale descriptions. To achieve the
science goal expressed in this report, a significant fraction of the
USGS human and infrastructure resources could be involved.

Such an undertaking demands clarity of purpose. Without such clarity,
the program will almost certainly disintegrate into a number of
independent - or worse, competing - activities. But clarity of purpose
does not imply a single monolithic activity; rather, a viable structure
can be assembled as a geographic or thematic mosaic. What is essential
is that the tiles of the mosaic compatibly complete the larger picture.
As an example, the National Water Quality Assessment (NAWQA) program
employs a combined thematic mosaic (surface water and ground water) and
geographic mosaic (watershed and aquifer), resulting in a national
portrait of water-quality status and trends.

What is the picture that this program would assemble? Can it be a single
picture, or are multiple pictures needed in order to address the many
concerns that surround ecosystems and land use? What form does each
picture take - forecast model, status and trends description, or
assessment?

The goal statement presented at the beginning will require use of
mapping, modeling, monitoring, and assessment. The goal of mapping,
monitoring, and modeling is to expand knowledge; products of mapping and
modeling inform resource management and spark policy debate. The goal of
assessment, in contrast, is to translate knowledge into answers to
cultural and political questions (and most often integrate knowledge in
the process). Examples of the questions are... What is happening? How
sure are we of this knowledge? Do we need to be concerned? Where do we
need to focus our concern? Do we need to take action now, or can action
wait? What actions might address our concerns? What are the relative
costs, effects, and side effects of candidate actions? These (and other)
questions can be answered most effectively if mapping is comprehensive
and if models can be manipulated with various scenarios of natural and
human influence.

# **Summary** {#summary-1 .unnumbered}

Changes in land cover and land use are occurring at an increasingly
rapid rate. Some 40 to 50 percent of land worldwide has been transformed
through changes in land cover or degraded by human actions. Natural
forests continue to disappear at a rate of 14 million hectares each
year. Other important ecosystems have also been substantially reduced or
degraded by human activity. These activities are already beginning to
threaten the continued provision of goods and services produced in
ecological systems and the effectiveness of ecosystem-level processes of
importance to human activities. The sustainability of these goods and
services depends on the recognition that the integrity of ecosystems and
ecological processes is linked in part to changes in land surface cover
and intensification in land management regimes. A better understanding
of the rate and direction of change in the Nation's ecosystems is
important for guiding the management of our natural resources and
resolving debates that range over policy decisions by federal land
management agencies, as well as those affecting private landowners.

The U.S. Geological Survey has a major responsibility to provide
leadership in understanding the consequences of land cover and land use
change on ecosystem integrity and developing sound science that will
support assessments of ecosystem condition and performance. An
integrated research approach with a focus on ecosystem integrity,
sustainability, and land surface change is necessary. The ability to
predict future changes requires an improved understanding of the causes
and mechanisms that underlie current and past changes in land cover.
Research that investigates the functional consequences of land-cover and
land-use changes for ecosystems needs to be conducted. New research also
needs to be initiated that examines how ecosystems react to change. An
understanding of ecosystem response to changes in the factors that drive
ecosystem behavior in both natural and human dominated systems is
important in order to prescribe ecosystem restoration and management
strategies that would enhance the sustainability of Earth's ecological
systems. New tools and methodologies must be developed to strengthen the
capacity to assess the sustainability of ecosystems to provide goods and
services and the potential consequences of future changes in ecosystems.
Improved predictive models including decision support systems for
land-use planning and improved assessment of the likely outcomes of
alternative land-use scenarios must be developed that will help guide
managers in their activities.

The scientific call for research on ecosystem integrity, sustainability,
and land surface change has assumed a priority. There is an urgent need
to understand how the land-water-atmosphere system responds to land
surface change. Efforts by the U.S. Global Change Research Program and
the International Geosphere-Biosphere Program have moved an
understanding of land surface change and dynamics and the consequences
on ecosystem integrity to a central role. The National Research Council
and the Ecological Society of America have issued reports on the
importance of understanding the ecological consequences resulting from
changes in land-use. And the United Nations and the World Bank is
leading an international effort to assess the health of the world's
biological systems and the impact of that health on the goods and
services ecosystems provide. A greater technical capacity to support
integrated and proactive management decisions, particularly on a
regional scale, is needed. The USGS can add to this effort by taking a
lead role in using long-term studies, landscape scale experimentation,
the development of improved modeling tools, and new technologies to
address the critical issues in understanding the causes and mechanisms
of land surface change and the subsequent consequences on ecosystem
integrity and the sustainability of ecosystem processes.

Empirical studies that manipulate key forcing factors will be required
and should be conducted at both appropriate temporal and spatial scales.
Determining the relationship between land-use and ecological processes
is difficult to accomplish, however, because the broad spatial-temporal
scales involved make experimentation and hypothesis testing challenging.
Thus achieving this goal will also require the extrapolation of results
obtained from small-scale experiments to broad scales. Models are a
necessary component of this science strategy because experiments are
frequently not feasible at the ideal spatial or temporal scale. Because
most ecological modeling has focused on temporal change, spatial
stimulation modeling is not yet well developed. Yet the linking of
ecosystem models with geographic information systems and remote sensing
technologies is a critical component of this agenda.

Predicting the consequences of land cover change and developing a more
precise understanding of basic landscape dynamics requires the
development of new insights and understanding of the factors leading to
past changes in land cover patterns and characteristics. New
quantitative methods are needed to identify significant changes in land
cover characteristics through time and relate these changes to
ecological functions. One of the highest priorities includes acquiring
improved data and better means of monitoring ongoing changes in land use
and cover. Predictive models that forecast land use changes and their
consequences on ecosystem integrity and sustainability are critically
needed.

Important questions remain about the causes of land cover change and
subsequent ecosystem impacts. What constitutes a significant change in
land cover, which measures of this change best relate to ecological
processes, and how does the measurement of the change relate to the
scale of the underlying processes? We need to better understand the
connection between the sequence of land use change, land cover
alteration, and ecosystem characteristics.

It is important to identify the processes and scales at which land use
change has a significant influence on ecosystem dynamics. But the broad
scale nature of the important questions require creative approaches.
Theoretical and empirical work should be employed to make progress in
the development and testing of a new general theory relating land use
change and ecosystem consequences at a variety of temporal and spatial
scales.

The coverage and resolution of the new generation of remote sensing
instruments combined with long-term data sets pertaining to ecosystem
condition, and significant advances in the development of ecological
indicators must be used with new insights into the impact of land-use
change on critical ecosystem processes to develop assessment and
monitoring strategies of ecosystems and ecosystem functions. We must
develop more useful measures of the condition of ecosystems for use by
managers and policy makes. These evaluations will typically involve both
examination of historical trends and measures of the various biophysical
features of ecosystems. We must understand and assess threshold
responses of ecosystems that might occur in response to changes in
driving forces. An increased assessment capability will also be
important in evaluating the strengths and weaknesses of various
management decisions, legislative policy, or other actions proposed to
improve the management of ecosystems.

The infrastructure requirements needed to address the science proposed
in this initiative will require the development of new skills in the
U.S. Geological Survey, closer cooperation and interaction among
scientists from across the Survey, greater use and development of
spatial technologies, and increased field experimentation. We will need
to add expertise in socio-economic systems to better complement existing
strengths in understanding the driving forces of landscape change and
subsequent ecosystem affects.

The USGS must also work in partnership with other programs and
initiatives. Comprehensive assessments of the condition of ecosystems
are a priority at both National and International levels. Many of these
initiatives involve the use of existing databases and methodologies. The
USGS can be a leader in developing and maintaining the appropriate
long-term ecological and ecoregional databases needed for such
assessments.

# **References** {#references .unnumbered}

Allen T.F.H., and Starr, T.B., 1982, Hierarchy: Perspectives for
Ecological Complexity: Chicago, The University of Chicago Press, 310 p.

Berkes, F. and Folke, C., 1998. Management practices and social
mechanisms for building resilience. pp. 1-26): In F. Berkes and C. Folke
(Eds). Linking Social and Ecological systems: Cambridge, UK: Cambridge
University Press.

Borchert, J.R., 1967. American metropolitan evolution. Geographical
Review 57: 301-332.

Bryce, S.A., Omernik, J.M., and Larsen, D.P., 1999. Ecoregions: a
geographic framework to guide risk characterization and ecosystem
management. Environmental Practice 1: 141-155.

Carpenter, S. R., Fisher, S. G., Grimm, N. B. and Kitchell. J. F., 1992.
Global change and freshwater ecosystems. Annual Review of Ecology and
Systematics 23:119-139.

Carpenter, S.R. and Cottingham, K.L., 1997. Resilience and restoration
of lakes. Conservation Ecology. 1: 2.

Chapin, F. S., III, McGuire, A. D., Randerson, J., Pielke, R. Sr.,
Baldocchi, D., Hobbie, S. E., Roulet, N., Eugster, W., Kasischke, E.,
Rastetter, E. B., Zimov, S. A., and Running S. W., 2000. Arctic and
boreal ecosystems of western North America as components of the climate
system. Global Change Biology 6:1-13.

Chapin III, F.S., Sala, O.E., Burke, I.C., Grime, J.P., Hooper, D.U.,
Lauenroth, W.K., Lombard, A., Mooney, H.A., Mosier, A.R., Naeem, S.,
Pacala, S.W., Roy, J., Steffen, W.L., and Tilman, D., 1998. Ecosystem
consequences of changing biodiversity: experimental evidence and a
research agenda for the future. BioScience 48(1): 45-52.

Christensen, N.L., Bartuska, A.N., Brown, J.H., Carpenter, S.,
D'Antonio, C., Francis, R., Franklin, J.F., MacMahon, J.A., Noss, R.,
Parsons, D.J., Petersen, C.H., Turner, M.G., Woodmansee, R.G., 1996. The
report of the ecological society of America committee on the scientific
basis for ecosystem management. Ecological Applications 6:665-691.

Copeland, J.H., Pielke, R.A., and Kittel, T.G.F., 1996. Potential
climatic impacts of vegetation change: a regional modeling study.
Journal of Geophysical Research 101(ND3): 7409-7418.

Correll, D. L. 1997. Buffer zones and water quality protection: general
principles. Pages in N. E. Haycock, T. P. Burt, K. W. T. Goulding, and
G. Pinay, editors. Buffer Zones: Their Processes and Potential in Water
Protection. Quest Environmental, Harpenden.

Costanza, R., 1992. Toward an operational definition of ecosystem
health. In R. Costanza, B. G. Norton, and B. D. Haskell (Eds.) Ecosystem
health: New goals for environmental management. Island Press,
Washington, DC. pp. 239-256.

Daily, G.C., 1995. Restoring value to the world\'s degraded lands.
Science 269: 350-354.

Dale, V.H., Brown, S., Haeuber, R.A., Hobbs, N.T., Huntley, N., Naiman,
R.J., Riebsame, W.E., Turner, M.G., and Valone T.J., 2000. Ecological
principles and guidelines for managing the use of land. Ecological
Applications 10: 639-670.

Delcourt, H.R., Delcourt, P.A., and Webb III, T., 1983. Dynamic plant
ecology: the spectrum of vegetational change in space and time.
Quaternary Science Reviews 1: 153-175.

Diamond, H.L. and Noonan, P.F., 1996. Land Use in America. Washington,
DC, Island Press 351 p.

Eblen, R. A. and Eblen W., 1994. The Encyclopedia of the Environment.
Houghton Mifflin Company, Boston.

Enquist, B.J. and Niklas, K.J., 2001, Invariant scaling relations across
tree-dominated communities: Nature, vol. 410, p. 655-660.

Fahrig, L., and Merriam, G., 1985. Habitat patch connectivity and
population survival. Ecology 66:1762-1768.

Farnsworth, N. R., and Soejarto, D. D. 1985. Potential consequence of
plant extinction in the United States on the current and future
availability of prescription drugs. Economic Botany 39 (3): 231-40.

Field, C.B. and Fung, I.Y., 1999. The not-so-big U.S. carbon sink.
Science 285: 544-545.

Foster, D.R. 1988. Disturbance history, community organization, and
vegetation dynamics of the old-growth Pisgah Forest, southwestern New
Hampshire, USA. Journal of Ecology 76:105-134.

Gober, P., 2000. In search of synthesis. Annals of the Association of
American Geographers 90(1):1-11.

Griffiths B.S., Ritz K., Bardgett R.D., Cook R., Christensen S., Ekelund
F., Sørensen, S.J., Bååth E., Bloem J., de Ruiter P.C., Dolfing J.,
Nicolardot B., 2000. Ecosystem response to pasture soil communities to
fumigation-induced microbial diversity reductions: an examination of the
biodiversity\--ecosystem function relationship: Oikos, 2000, vol. 90,
no. 2, p. 279-294.

Guntenspergen, G.R., Cahoon, D.R., Grace, J., Steyer, G.D., Fournet, S.,
Townson, M.A., and Foote A.L., 1995. Disturbance and recovery of the
Louisiana coastal marsh landscape from the impacts of Hurricane Andrew.
Journal of Coastal Research 18: 324-339.

Hector, A., and others, 1999. Plant diversity and productivity
experiments in European grasslands. Science 286: 1123-1127.

Heinselman, M. L. 1973. Fire in the virgin forests of the Boundary
Waters Canoe Area, Minnesota. Quaternary Research 3:329-382.

Houghton, R.A., Hackler, J.L., and Lawrence, K.T., 1999. The U.S. carbon
budget: contributions from land-use change. Science 285: 574-577.

International Geosphere Biosphere Programme, 1993. Relating Land Use and
Global Land-Cover Change: A Proposal for an IGBP-HDP Core Project, B.L.
Turner II, R.H. Moss, and D.L. Skole, editors. IGBP Global Change Report
No. 24, International Geosphere Biosphere Programme, Stockholm 65 p.

Jones, B.K., Shaw, D.M., Czaplewski, R., and Norton, D.J., 1995.
Integrated landscape monitoring: conceptual approaches and applications.
Toxicological and Environmental Chemistry 49: 109-117.

Kelmelis, J.A., 1993. Terrestrial process research using a multiscale
geographic approach. Photogrammetric Engineering and Remote Sensing
59(6): 971-976.

Klopatek, J.M., Olson, R.J., Emerson, C.J., and Joness, J.L., 1979.
Land-use conflicts with natural vegetation in the United States.
Environmental Conservation 6(3): 191-199.

Knapp, A.K. and Smith, M.D., 2001. Variation among biomes in temporal
dynamics of above ground primary production: Science 294: 481-484.

Knapp, R.A., Matthews, K.R., and Sarnelle, O., 2001. Resistance and
resilience of alpine lake fauna to fish introductions: Ecological
Monographs 71(3): 401--421.

Kusler, J.A. and Kentula, M.E., 1990. Wetland Creation and Restoration:
The Status of the Science. Island Press, Washington, D.C.

Loreau, M., Naeem, S., Inchausti, P., Bengtsson, J., Grime, J.P.,
Hector, A., Hooper, D.U., Huston, M.A., Raffaelli, D., Schmid, B.,
Tilman, D., and Wardle, D.A., 2001. Biodiversity and ecosystem
functioning: current knowledge and future challenges. Science 294:
804-808.

Loveland, T.R., 2000. The patterns and characteristics of global land
cover. In Spatial Information for Land Use Management, M. Hill and R.
Aspinall, eds. London, Gordon and Breach 13-38.

Loveland, T.R., Sohl, T., Stehman, S.V., Gallant, A.S., and Sayler, K.,
2001. A strategy for estimating the rates and causes of recent United
States land cover changes. Photogrammetric Engineering and Remote
Sensing (submitted).

Marceau, D.J., 1999. The scale issue in the social and natural science.
Canadian Journal of Remote Sensing 25(4): 347-356.

Matson, P.A., Parton, W.J., Power, A.G., and Swift, M.J., 1997.
Agricultural intensification and ecosystem properties. Science 277:
504-509.

McKendry, J.E. and Machlis, G.E., 1993. The role of geography in
extending biodiversity gap analysis. Applied Geography 11: 135-152.

McNaughton, S. J. 1979. Grazing as an optimization process:
grass-ungulate relationships in the Serengeti. American Naturalist
113:691-703.

Meyer, W.B., Gregory, D., Turner II, B.L., and McDowell, P.F., 1992. The
local-global continuum. Geography's Inner Worlds: Pervasive Themes in
Contemporary American Geography, R.F. Abler, M.G. Marcus, and J.M.
Olson, eds. New Brunswick, NJ, Rutgers University Press 255-279.

Mitsch, W.J. and Gosselink, J.G., 2000. Wetlands. John Wiley and Sons,
Inc.

Mladenoff, D.J. and Baker, W.L., eds. 1999. Spatial Modeling of Forest
Landscape Change: Cambridge, UK, Cambridge University Press.

Myers, N., Mittermeier, R.A., Mittermeier, C.G., da Fonseca, G.A.B., and
Kent, J., 2000. Biodiversity hotspots for conservation priorties. Nature
403: 853-858.

Myers, R.L., 1985. Fire and the dynamic relationship between Florida
sandhill and sand pine scrub vegetation. Bulletin of the Torrey
Botanical Club 112:241-252.

National Research Council, 1999. Measures of Environmental Performance
and Ecosystem Condition, National Academy Press, Washington, DC 312p.

National Research Council, 2000. Ecological Indicators for the Nation.
National Academy Press, Washington, DC 198p.

National Research Council, 2001a. Future Roles and Opportunities for the
U.S. Geological Survey. Washington, D.C., National Academy Press 179 p.

National Research Council, 2001b. Grand Challenges in Environmental
Sciences. Washington, DC, National Academy Press 96 p.

Noss, R.F., 1990. Indicators for monitoring biodiversity: a hierarchical
approach. Conservation Biology 4(4): 355-364.

Nunes, C. and Augé, J.J., eds., 1999. Land-Use and Land-Cover Change
Implementation Strategy, IGBP Report 48. International Geosphere
Biosphere Programme Secretariat, Stockholm, Sweden 125 p.

Office of Technology Assessment, 1993. Harmful Non-Indigenous Species in
the United States. U.S. Government Printing Office, Washington, D.C.,
1993.

O'Neill, R.V., DeAngelis, D.L., Waide, J.B., and Allen, T.F.H., 1986, A
hierarchical concept of ecosystems: Princeton, NJ, Princeton University
Press, 253 p.

Owen-Smith, R. N. 1988. Megaherbivores: the Influence of Very Large Body
Size on Ecology. Cambridge University Press, Cambridge.

Paerl, H.W., Bales, J.D., Ausley, L.W., Buzzelli, C.P., Crowder, L.B.,
Eby, L.A., Fear, J.M., Go, M., Peierls, B.L., Richardson, T.L., and
Ramus, J.S., 2001, Ecosystem impacts of three sequential hurricanes
(Dennis, Floyd, and Irene) on the United States\' largest lagoonal
estuary, Pamlico Sound, NC: Proceedings of the National Academy of
Sciences USA, vol. 98, no. 10, 5655-5660.

Pastor, J. and Post, W. M., 1986. Influence of climate, soil moisture,
and succession on forest carbon and nitrogen cycles. Biogeochemistry 2:
3-27.

Pickett, S. T. A. and White, P. S., 1985. The Ecology of Natural
Disturbance as Patch Dynamics. Academic Press, New York.

Quattrochi, D.A. and Pelletier, R.E., 1990. Remote sensing for analysis
of landscapes: an introduction. In Quantitative Methods in Landscape
Ecology, Monica G. Turner and Robert H. Gardner, eds. Springer-Verlag,
New York 51-76.

Riebsame, W.E., Parton, W.J., Galvin, K.A., Burke, I.C., Bohren, L.,
Young, and Knop, E., 1994. Integrated modeling of land use and cover
change. BioScience 44(5): 350-356.

Ritchie, M.E., 1999. Spatial scaling laws yield a synthetic theory of
biodiversity: Nature 400: 557-560.

Roughgarden, J., Running, S.W., and Matson, P.A., 1991. What does remote
sensing do for ecology? Ecology 72(6): 1918-1922.

Schindler, J.E., and others, 1980. A microcosm approach to the study of
biogeochemical systems. 1. Theoretical rationale: United States
Department of Energy Symposium Series 52, CONF-781101 192-203.

Steffen, W.L., Walker, B.H., Ingram, J.S.I., and Koch, G.W., 1992.
Global Change and Terrestrial Ecosystems: The Operational Plan. IGBP
Global Change Report No. 21, International Geosphere Biosphere
Programme, Stockholm, Sweden 95 p.

Tilman, D., Dodd, M. E., Silvertown, J., Poulton, P. R., Johnston, A. E.
& Crawley, M. J., 1994. The park grass experiment: insights from the
most long-term ecological study: In Long-term experiments in
agricultural and ecological sciences R. A. Leigh & A. E. Johnston, eds.
CAB International, Wallingford, UK 287-303

Tilman, D., Reich, P.B., Knops, J., Wedin, D., Mielke, T., and Lehman,
C., 2001. Diversity and productivity in a long-term grassland
experiment: Science 294: 843-845.

Turner, B.L., II, Skole, D., Sanderson, S., Fischer, G., Fresco, L., and
Leemans, R., 1995. Land-Use and Land-Cover Change: Science/Research
Plan. IGBP Report No. 35, HDP Report No. 7, International
Geosphere-Biosphere Programme, Stockholm, Sweden 132 p.

Turner, M.G., Gardner, R.H., and O'Neill, R.V., 1995. Ecological
dynamics at broad scales. BioScience 45: (Supplement) S29-S35.

Turner, M.G. and Dale, V.H. 1998. Comparing large, infrequent
disturbances: what have we learned? Ecosystems 1: 493-496.

Vitousek, P.M., Mooney, H.A., Lubchenco, J., and Melillo, J.M., 1997.
Human domination of the Earth. Science 277: 494-499.

# **List of Tables** {#list-of-tables .unnumbered}

Table 1. Land cover change in East-Central United States ecoregions.

Table 2. Staffing needs, special skills, and levels.

Table 3. Datasets required for ecosystem health, sustainability, and
land surface change.

Table 1. Land cover change in East-Central United States ecoregions.

Table will be fixed in next version

Table 2. Staffing needs, special skills, and levels.

  ---------------------- ------------------------------- ----------------
  Discipline             Special Skills                  Levels

  Statistics             Sampling design, scaling        PhD.

  Ecology                Ecological modeling, landscape  PhD.
                         scale                           

  Ecology                Biophysical remote sensing,     PhD.
                         spatial technologies            

  Ecology                Large-area integration          

  Ecology                Ecosystem structure and         PhD., MS
                         function mapping, remote        
                         sensing                         

  Ecology                Quantitative ecology, systems   PhD.
                         analysis, operations analysis   

  Paleoecology           Natural vegetation histories    PhD., MS

  Geography              Future land use modeling        PhD.

  Geography, Social      Driving forces research         PhD.
  Sciences                                               

  Geography              Regional geography,             PhD.
                         ecoregionalization              

  Geography              Land use histories              PhD., MS

  Computer Science       Visualization, object-oriented  MS
                         programming                     
  ---------------------- ------------------------------- ----------------

Table 3. Datasets required for ecosystem health, sustainability, and
land surface change.

  ----------------- -------------- -------------- -------------------------
  Database Variable Time Period    Current        Comments
                                   Availability   

  Contemporary      1992-ongoing   USGS Gap       Emphasis on floristics
  Natural                          Analysis       and alliances
  vegetation                       Program        

  Historical        100,000 years  USGS Earth     Requires additional
  natural           ago to 1700 AD Surface        research and temporal
  vegetation                       Dynamics       expansion

  Land use and land 1970's         USGS National  Provides national land
  cover             -ongoing       Land Cover     cover every 10 years
                                   Database       

  Landscape natural 2000- ongoing  None           Consistent mapping of
  disturbances                                    major disturbance events
                                                  (fires, storms, flooding,
                                                  etc.)

  Land cover/use    1972 - ongoing USGS Land      Research project with no
  change                           Cover Trends   operational mandate
                                   Project        

  Land use history  1700 - 1972    LUHNA          USGS BRD Prototype

  Ecosystems and    Contemporary   Other agency   May require modification
  ecoregions        conditions     maps (USFS,    to meet needs of this
                                   EPA)           research

  Ecosystem         2000 - ongoing None           Systematic documentation
  physiognomy                                     of patterns of vegetation
                                                  age, height, density, and
                                                  leaf area

  Ecosystem         1990's -       USGS-NPS       Too limited in geographic
  floristics        ongoing        Vegetation     coverage, under-funded
                                   Mapping        
                                   Program        

  Ecosystem         2000 - ongoing None           Net ecosystem
  productivity                                    productivity, net primary
                                                  productivity
  ----------------- -------------- -------------- -------------------------

# **List of Figures** {#list-of-figures .unnumbered}

Figure 1. Pre-European settlement land cover versus Actual cover of the
conterminous United States.

Figure 2. The process for investigating the extent and impacts of land
surface change on ecosystem health and sustainability is based on
mapping, monitoring, and modeling.

Figure 3. Illustration of relationships between ecosystems, global
environmental systems, and people. Economic costs and benefits of
human-ecosystem interactions are a significant driver of ecosystem
change, and are a central element of this science plan.

Figure 4. Land cover of the Conterminous United States.

Figure 5. The ecosystem is a manifestation of forcing factors and
feedback loops across space and time. The current landscape
configuration is in dynamic flux, either maintaining an equilibrium
state or in the process of change driven by alterations in the balance
of forces acting on the landscape mosaic. In recent history, human
activities have accelerated, tipping the scale, and creating an
imbalance in even the most stable system. A realistic evaluation of
ecosystem condition will be grounded in the ability to understand the
past, to realize the present condition, and to visualize future
potential scenarios of dynamic processes and their temporal and spatial
manifestations.

Figure 6. Conceptual model of an aquatic ecosystem as a hierarchical
system.

Figure 7. Illustration of the use of remote sensing and other geographic
data as a linkage between local-scale monitoring and larger-scale
monitoring. The linkage demands expertise in multiple disciplines:
biology, ecology, remote sensing, statistics, advanced information
analysis (such as neural networks), and geographic analysis.

Figure 8. Illustration of factors that influence deforestation through
commercial logging. The five factor-group structure is the same
structure that is used in analysis and modeling of urban growth.
Development of common frameworks and approaches applicable to many types
of land-surface change will be a key in developing regional- and
national-scale models.

Figure 9. Diagram showing some of the factors that people balance when
choosing their place of residence. Understanding geographic shifts of
population is necessary in order to understand land-use change.
Socioeconomic research on the factors shown in the diagram is a
prerequisite to forecasting migration.

Figure 10. Changes to Pamlico Sound following Hurricane Floyd.

Figure 11. Diagram depicting a strategy for linking local (metropolitan-
or landscape-scale) models of land surface change to regional models.
High-resolution data products may not be available to drive
regional-scale models, so surrogate products must be utilized. The
surrogate drivers require statistical study and validation.

![](media/image1.png){width="4.875in" height="3.066666666666667in"}

![](media/image2.png){width="4.875in" height="3.0743055555555556in"}

Figure 1. Land cover of the Conterminous United States before European
settlement (above) and now (below).

![](media/image3.png){width="4.786111111111111in"
height="2.990972222222222in"}

Figure 2. The process for investigating the extent and impacts of land
surface change on ecosystem health and sustainability is based on
mapping, monitoring, and modeling.

![](media/image4.wmf){width="6.0in" height="3.60625in"}

Figure 3. Illustration of relationships between ecosystems, global
environmental systems, and people. Economic costs and benefits of
human-ecosystem interactions are a significant driver of ecosystem
change, and are a central element of this science plan.

![](media/image5.jpeg){width="6.009722222222222in"
height="4.506944444444445in"}

Figure 4. Land Cover area for the Conterminous United States.

![](media/image6.png){width="4.686111111111111in"
height="6.684027777777778in"}

Figure 5. The ecosystem is a manifestation of forcing factors and
feedback loops across space and time. The current landscape
configuration is in dynamic flux, either maintaining an equilibrium
state or in the process of change driven by alterations in the balance
of forces acting on the landscape mosaic. In recent history, human
activities have accelerated, tipping the scale, and creating an
imbalance in even the most stable system. A realistic evaluation of
ecosystem condition will be grounded in the ability to understand the
past, to realize the present condition, and to visualize future
potential scenarios of dynamic processes and their temporal and spatial
manifestations.

![](media/image7.png){width="5.297916666666667in"
height="8.124305555555555in"}

Figure 6. Conceptual model of an aquatic ecosystem as a hierarchical
system.

![](media/image8.wmf){width="5.875in" height="4.488888888888889in"}

Figure 7. Illustration of the use of remote sensing and other geographic
data as a linkage between local-scale monitoring and larger-scale
monitoring. The linkage demands expertise in multiple disciplines:
biology, ecology, remote sensing, statistics, advanced information
analysis (such as neural networks), and geographic analysis.

![](media/image9.wmf){width="5.884722222222222in"
height="4.281944444444444in"}

Figure 8. Illustration of factors that influence deforestation through
commercial logging. The five factor-group structure is the same
structure that is used in analysis and modeling of urban growth.
Development of common frameworks and approaches applicable to many types
of land-surface change will be a key in developing regional- and
national-scale models.

![](media/image10.wmf){width="6.0in" height="4.040972222222222in"}

Figure 9. Diagram showing some of the factors that people balance when
choosing their place of residence. Understanding geographic shifts of
population is necessary in order to understand land-use change.
Socioeconomic research on the factors shown in the diagram is a
prerequisite to forecasting migration.

![](media/image11.jpeg){width="3.50625in" height="8.377777777777778in"}

Figure 10. Changes to Pamlico Sound following Hurricane Floyd.

![](media/image12.wmf){width="6.0in" height="4.327083333333333in"}

Figure 11. Diagram depicting a strategy for linking local (metropolitan-
or landscape-scale) models of land surface change to regional models.
High-resolution data products may not be available to drive
regional-scale models, so surrogate products must be utilized. The
surrogate drivers require statistical study and validation.