Assessing Forest Sustainability in the 

Tropical Islands of the United States

Kathleen A. McGinley, Guy C. Robertson, Kathleen S. Friday, and 

Constance A. Carpenter

United States Department of Agriculture

Forest 

Service

International Institute 

of Tropical Forestry

General Technical Report

IITF-GTR-48

November

2017
Authors

Kathleen A. McGinley is a research social scientist, U.S. Department of Agriculture, 

Forest Service, International Institute of Tropical Forestry, 1201 Calle Ceiba, San Juan, 

Puerto Rico 00926, kmcginley@fs.fed.us; Guy C. Robertson is National Program Leader 

for Sustainability Assessment, U.S. Department of Agriculture, Forest Service, 1400 

Independence Ave. SW, Washington, DC 20250, grobertson02@fs.fed.us; Kathleen S. 

Friday is Pacific Islands Forest Stewardship and Legacy Program Manager, U.S. Department of Agriculture, Forest Service, Pacific Southwest Region, Institute of Pacific Islands 

Forestry, 60 Nowelo St., Hilo, HI 96720; Constance A. Carpenter is a State and Private 

Forestry representative, U.S. Department of Agriculture, Forest Service, Durham Field 

Office, 271 Mast Road, Durham, NH 03824.

Cover: The rock islands of the Palau archipelago. Photo by LuxTonnerre.

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Assessing Forest Sustainability in the Tropical Forests of the United States i

McGinley, Kathleen A.; Robertson, Guy C.; Friday, 

Kathleen S.; Carpenter, Constance A. 2017. Assessing 

forest sustainability in the tropical islands of the United 

States. Gen. Tech. Rep. IITF-GTR-48. San Juan, PR: 

U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry. 115 p.

This report is a companion report to the National Report 

on Sustainable Forests, except that the analysis in this 

case is specifically applied to tropical forests found on 

U.S. islands and U.S.-affiliated island jurisdictions in 

the Caribbean Sea and Pacific Ocean. Like its national 

counterpart, the report uses the Montréal Process Criteria and Indicators for Sustainable Forest Management 

(MP C&I) to provide a comprehensive picture of forest 

conditions. Each of the seven criteria in the MP C&I 

is given a separate chapter, and the resulting analysis 

includes consideration of ecological, social, economic, 

and institutional dimensions of forest sustainability.

Our key findings mirror those of the 2010 national 

report: tropical forests on the U.S. islands are not 

experiencing broad-scale deforestation, and forest area 

is stable in most jurisdictions. However, these forests 

are facing multiple threats from environmental and 

anthropogenic stressors. With 760 plant and animal 

species across all the islands identified as at risk of 

extinction by the International Union for the Conservation 

of Nature, the threat of native biodiversity loss from 

extinction and extirpation, particularly in the Pacific, is 

the biggest warning flag regarding forest sustainability. 

In the Caribbean, where islands are relatively closer 

to each other and to the mainland than islands in the 

Pacific, and where past agricultural practices resulted in 

broad-scale disruption of native forest ecosystems, new 

assemblages of forest species are evolving, some including native and nonnative species, though most are still in 

relatively young age classes. On the social and economic 

front, commodity wood production plays a minimal to 

nonexistent role in island economies, but forests provide 

numerous benefits to island peoples, the importance of 

which are often enhanced by the limited space and close 

local social-ecological interactions reinforced by island 

geography and by long-established patterns of use on the 

part of local residents. Institutionally, many of the islands 

face considerable challenges resulting from a lack of 

economies of scale and sufficient resources for effective 

forest management. 

Keywords: Tropical forests, U.S.-affiliated islands, forest 

sustainability, criteria and indicators, nonnative species.

Abstract

Assessing Forest Sustainability in the Tropical Forests of the United States
ii Assessing Forest Sustainability in the Tropical Forests of the United States

This comprehensive synthesis of information about forests 

on the U.S. tropical islands and affiliated jurisdictions 

relies on a great deal of substantive work by experts who 

focused on particular regions and specific areas within 

the broad discipline of forestry. Much of this effort is 

reflected by the references accompanying each chapter, but 

considerable work was devoted to the project that could not 

be presented in published form, without which this report 

would not have been possible.

The project began with the compilation of individual 

indicator reports for each of the nine island jurisdictions 

that were covered. This was a major undertaking; although 

publishing each of these indicator reports was not feasible, 

they helped lay the foundation for the entire project. Karen 

Bennett (formerly with the U.S. Forest Service’s Institute 

of Pacific Islands Forestry, or IPIF) led this effort in the 

Pacific and was later succeeded by Kathleen Friday (IPIF/

Pacific Southwest Region State and Private Forestry). 

From the U.S. Forest Service’s International Institute of 

Tropical Forestry (IITF), Kathleen McGinley (Research 

and Development) and Constance Carpenter (State and 

Private Forestry) worked on these island-specific reports 

for the Caribbean. Leo Zhangfeng-Liu and Lisa Fischer 

(contractor for and formerly with Pacific Southwest 

Region State and Private Forestry, respectively), Thomas 

Brandeis (U.S. Forest Service Southern Research Station), 

and Eileen Helmer (IITF research ecologist) added 

essential pieces to the puzzle.

More generally, we have made repeated use of certain key 

data sources and key information contacts, particularly 

in regard to forest inventory information provided by the 

Forest Inventory and Analysis program. In addition to 

Thomas Brandeis, Joseph Donnegan and Olaf Kuegler 

(both at the U.S. Forest Service Pacific Northwest 

Research Station) deserve special thanks here.

We thank our numerous reviewers for the time and 

focused attention they gave to this report in its preparation. More than 20 people provided review comments 

on specific chapters or on the document as a whole. In 

many cases, these comments were quite extensive, and 

all resulted in important improvements to the report.

Special thanks also go to Olga Ramos (IITF, GIS and 

Remote Sensing Lab), who provided many of the maps 

used in the publication, and Keith Routman (U.S. Forest 

Service Pacific Northwest Research Station) for his 

substantial work in editing and designing this document.

The Statewide Assessments and Resource Strategies 

(SWARS—subsequently called Forest Action Plans) 

provided essential background for many of the sustainability criteria addressed in this report, particularly the 

more qualitative assessments presented for Criterion 6 

(social and economic conditions) and Criterion 7 (institutional framework). We cannot acknowledge by name 

each of the many island forestry staff and contractors who 

contributed to the SWARS, but their major contribution to 

this report and sustainable forest management in general 

is recognized.

Acknowledgments

Assessing Forest Sustainability in the Tropical Forests of the United States
Assessing Forest Sustainability in the Tropical Forests of the United States iii

Preface

Assessing Forest Sustainability in the Tropical Forests of the United States

In September 2017, two major hurricanes passed through 

the Caribbean, causing catastrophic damage to communities, infrastructure, and ecosystems across Puerto 

Rico, the U.S. Virgin Islands, and many other island 

jurisdictions throughout the region. Hurricane Irma was 

a category 5 storm when it passed directly over the U.S. 

Virgin Islands on September 6, 2017, causing flooding, 

landslides, and extensive structural damage, particularly 

on the island of St. Thomas. The outer bands of Hurricane 

Irma also grazed Puerto Rico, affecting natural and built 

infrastructure and leaving more than 1 million inhabitants 

(30 percent of the population) without power. Two weeks 

later, on September 20, 2017, Hurricane Maria, a second 

category 5 storm, made landfall on the southeast coast 

of Puerto Rico, traversing the island in its entirety, as its 

northern eyewall crossed over St. Croix in the U.S. Virgin 

Islands. Hurricane Maria, the strongest storm to make 

landfall in Puerto Rico since Hurricane San Felipe II in 

1928, produced widespread storm surges, flash floods, 

and landslides, and it resulted in unprecedented losses to 

infrastructure, crops, livestock, and natural vegetation 

across the islands. 

As this report goes to press, more than 50 deaths in Puerto 

Rico and the U.S. Virgin Islands have been attributed to 

Hurricanes Irma and Maria, and the costs of recovery are 

estimated in the tens of billions of dollars. Many of the 

residents of these islands remain without power and with 

only limited access to basic necessities and public services. Large expanses, once green, now appear brown in 

satellite imagery, reflecting the changes in vegetation after 

the hurricanes. Nevertheless, as noted throughout this 

report and specifically in the chapter covering Criterion 3 

(forest disturbance), hurricanes and storms are part of the 

cycle of island life. In the case of forests, they influence 

their structure, function, diversity, and composition. 

Many native island species have evolved to withstand 

strong storms and hurricanes and to recover rapidly after 

they have passed. As Dr. Ariel Lugo, director of the 

USDA Forest Service International Institute of Tropical 

Forestry in Puerto Rico, observed soon after the event, 

within 2 weeks of Hurricane Maria defoliated trees 

already had begun to sprout new leaves, demonstrating 

the resilience of island species. Similarly, Puerto Ricans 

and Virgin Islanders have shown great strength and 

determination as they begin to recover and rebuild. 

Future research on forest responses to Hurricanes Irma 

and Maria will expand existing long-term datasets and 

knowledge on forest recovery, and will shed new light on 

forest trajectories in the aftermath of back-to-back major 

storms. New research also should address how people 

respond to and recover from major storms and how such 

storms influence their perspectives on, activities in, 

uses of, and preferences for forests in natural to urban 

settings. Future assessments of tropical forest sustainability in Puerto Rico and the U.S. Virgin Islands should 

continue to examine a broad range of ecological, economic, and social elements and trends. We are confident 

that such assessments will only further document the 

enduring resilience of the people, cultures, and forests 

of these islands.
iv Assessing Forest Sustainability in the Tropical Forests of the United States

The tropical forests found on U.S.-affiliated islands in the 

Caribbean Sea and Pacific Ocean are unique and varied, 

as are the peoples who inhabit them. Comprising just 

0.2 percent of total U.S. land area, the islands span two 

hemispheres and possess a disproportionately large number 

of endemic species and distinctive ecosystem types. Moreover, each island has a unique history of human habitation 

and cultural development. The current status and future 

sustainability of the forests on these islands are the focus 

of this report.

The U.S. Forest Service’s National Report on Sustainable 

Forests, the next edition of which is slated for publication 

in 2018, assesses forest sustainability for the U.S. mainland using the Montréal Process Criteria and Indicators 

for Sustainable Forest Management (MP C&I). With 54 

indicators arranged under 7 criteria, the MP C&I constitutes an explicit and comprehensive information framework 

for assessing sustainability across ecological, social, and 

economic dimensions. This report extends this application 

to forests found on the U.S.-affiliated islands, treating each 

criterion in a separate chapter. 

Although the MP C&I provides a framework for information display and analysis, the actual assessment of 

sustainability is here addressed synthetically through 

summarization, first in criterion summaries for each 

criteria, and then in a compilation of key findings in a 

summary chapter. 

Key Findings

Are island tropical forests sustainable? This is a complex 

question with no easy “yes” or “no” answers and subject to 

varying interpretations. Readers are encouraged to reach 

their own conclusions based on the information presented 

in this report. In regard to the overarching question of 

forest sustainability, the report identifies 

three major findings:

• Forest area throughout the islands is relatively stable

(and has in fact increased substantially in the Caribbean 

over the past 75 years). This fact indicates sustainability 

from the crucial but very limited standpoint of maintaining forest extent.

•	 Native biodiversity in the Pacific Islands continues

to be threatened by various factors, notably the ongoing introduction of nonnative and invasive species,

resulting in the endangerment and extinction of endemic 

species—a significantly negative indication for forest 

sustainability.

• Novel assemblages of introduced and native tree 

species are maturing over large areas of the Caribbean, indicating the dynamic nature of forest ecosystems. 

These forests may support ecosystem system functions 

and biodiversity at levels comparable to native forests. 

However, their overall implications for sustainability 

are not yet fully understood and depend on both sustainability definitions and the future trajectory of these 

novel ecosystems.

Additional Major Findings 

• Approximately 3 million ac of tropical forests exist 

in the island jurisdictions considered in this report, 

ranging from nearly 1.5 million ac in the Hawaiian 

Islands to fewer than 24,000 ac in the Marshall Islands. 

Much of this forest land, particularly in Hawaii and 

the Caribbean, is composed of relatively young stands 

established on agricultural lands abandoned in the past 

century (see Criterion 1 in Part II).

• The number of extinctions and endangered species 

listings are the biggest warning flags regarding forest

sustainability. Some 760 plant and animal species 

across all the islands considered in this report are identified as at risk of extinction by the International Union 

for the Conservation of Nature. Hawaii stands out as 

particularly critical owing to its high number and rate 

of endemics and its number of endangered species (see 

Criteria 1 and 3 in Part II).

• The history of human settlement and subsequent 

patterns of land use strongly influence current forest

composition and structure throughout the islands.

Forest cover was virtually eliminated in Puerto Rico 

and the U.S. Virgin Islands (USVI) in the colonial 

period. Current forests in that region consist largely 

of trees in smaller size and younger age classes. The 

same is true for some but not all areas of Hawaii. 

U.S.-affiliated Pacific islands have experienced long 

histories of human occupation, with the introduction of 

various nonnative species and the integration of forests 

Executive Summary

Assessing Forest Sustainability in the Tropical Forests of the United States
Assessing Forest Sustainability in the Tropical Forests of the United States v

and agriculture in agroforestry systems, with resulting 

influences on forest structure and composition (see 

Criteria 1 and 2 in Part II).

• Climate change threatens entire islands and 

ecosystems. This report is focused on the assessment of 

current conditions, and the projected future impacts 

of climate change are generally beyond its scope. 

However, any assessment of the future sustainability 

of island forests must take into account the extreme 

susceptibility of tropical islands to sea-level rise, storm 

activity, and other impacts associated with climate 

change, especially atoll islands that are only a few feet 

above sea level. Moreover, most of the islands already 

feel the effects of the changing climate, particularly 

in terms of increasing variability and extremes in 

weather patterns.

• Commercial forestry is relatively limited; nevertheless, linkages between people and forests are 

very strong. Throughout the islands, forests provide 

agroforestry products, subsistence foods, medicinal 

compounds, wood for local crafts and construction, 

and other materials for cultural purposes and daily 

use. This reliance is compounded by the fact that, with 

the exception of Hawaii, per-capita incomes are less 

than half the U.S. average, and subsistence activities 

are concomitantly more important. Furthermore, the 

proximity and interaction of ecosystem components in 

island geographies enhances the importance of forests 

in the provision of ecosystem services such as drinking 

water, or sedimentation reduction in coastal waters (see 

Criteria 2 and 6 in Part II).

•	 Institutional capacity for forest management is

relatively limited, but islands partially compensate for this through regional collaboration and 

leveraging of available federal programs. The island 

jurisdictions covered by this report generally lack 

the resources and economies of scale to support the 

sorts of institutions that underlie forest management 

in the continental United States. In response, many 

of the islands engage in regional collaboration and 

exchange (in higher education, for example), and have 

instituted cross-boundary partnerships that incorporate 

nongovernmental organizations, citizen groups, 

local and federal governments, and private sector 

representatives (see Criterion 7 in Part II). 

• Data that are both consistent over time and comparable across island jurisdictions are relatively rare, 

but the situation is improving. The U.S. Forest Service Forest Inventory and Analysis (FIA) program has 

periodically measured forests in Puerto Rico since the 

mid 1980s and in the USVI since the mid 1990s. FIA 

activities also have more recently expanded to include 

tropical islands in the Pacific, and results will soon be 

available for the second measurement of some of the 

last islands to be included. U.S. Census and related 

socioeconomic data are not always directly comparable 

across different jurisdictions, especially for the U.S.-affiliated nations (Republic of the Marshall Islands, 

Federated States of Micronesia, and Republic of Palau), 

and various other datasets used for the mainland United 

States in the national report are not available for the 

tropical islands treated in this report (see chapter 2 in 

Part I).

Policy Recommendations

The report’s policy recommendations focus on information consolidation and fostering collaboration through 

the ongoing support of regional and federal bodies. 

Specific recommendations include the following:

• Pursue consolidation in data development and 

reporting. Comparability across time and space is 

hampered by a lack of repeated sampling. Ongoing 

improvements of forest inventory data, in particular, 

will help ameliorate the lack of consistent information 

on forests, but many important information gaps will 

remain. Specific recommendations related to data 

development and reporting are included at the end 

of chapter 2.

• Foster public participation and sensitivity to cultural differences as an essential component of

forest planning and management activities. Cultural 

relationships to the land differ considerably across 

stakeholder groups, as do styles of communication and 

political engagement. Public participation strategies and 

decisionmaking processes need to take these differences 

into account.

• Focus management and data acquisition activities on 

forest conditions and outputs that are most valued 

by island residents. Island inhabitants rely on forests 

for a broad range of services and outputs, few of which 

enter into formal markets or are subject to quantified 

measurement. To the extent possible, forest reporting 

and planning exercises need to explicitly identify 

these outputs and their relative importance, then 

use this information to tailor biological inventories, 

socioeconomic data collection, and management 

actions accordingly.

• Support ongoing collaboration between island 

entities through durable federal and regional 

programs. The value of federal programs and regional 

collaborations for small islands lacking capacity and 

economies of scale may not be fully understood in 

national venues, but these activities are critical to 

sustaining forest management activities on the islands.
vi Assessing Forest Sustainability in the Tropical Forests of the United States

Contents

Assessing Forest Sustainability in the Tropical Forests of the United States

Part I. Introduction and Summary

 I–1	 Chapter 1: Introduction

 Guy C. Robertson

 I–7 Chapter 2: Description of Available Data

 Guy C. Robertson and Kathleen S. Friday

I–19 Chapter 3: Tropcial Sustainability Key 

 Findings and Recommendations

 Guy C. Robertson, Constance A. Carpenter, 

 Kathleen S. Friday, and Kathleen A. McGinley

Part II. Criterion and Indicator Reports

 II-1 Criterion 1: Conservation of Biological Diversity

 Kathleen A. McGinley and Constance A. Carpenter

II-23 Criterion 2: Maintenance of the Productive 

 Capacity of Forest Ecosystems

 Kathleen A. McGinley

II-33 Criterion 3: Maintenance of the Ecosystem 

 Health and Vitality

 Kathleen S. Friday

II-43 Criterion 4: Conservation and Maintenance of 

 Soil and Water Resources

 Kathleen A. McGinley

II-53 Criterion 5: Maintenance of Forest Contribution 

 to Global Carbon Cycles

 Kathleen S. Friday

II-59 Criterion 6: Long-Term Multiple Socioeconomic 

	 	 Benefits to Meet the Needs of Societies

 Guy C. Robertson and Constance A. Carpenter

II-71	 Criterion 7: Legal, Institutional, and Economic

 Framework for Sustainable Forest Management

 Guy C. Robertson and Kathleen S. Friday

List of Tables

I-2 Table 1-1. Characteristics of island jurisdictions 

 considered in this report

I-5 Table 1-2. Montréal Process Criteria and 

 Indicators criterion summary

I-8 Table 2-1. Data sources for assessing tropical 

 forest sustainability in U.S. territories

I-9 Table 2-2. Forest reporting activities engaged in 

 by U.S. tropical islands

I-9 Table 2-3. Forest Inventory and Analysis 

 inventory status in tropical islands

I-10 Table 2-4. Vegetation type mapping status in 

 tropical islands

I-12 Table 2-5. Summary of data tables provided in 

 FAO 2010 Global Forest Resource Assessment 

(GFRA) country reports

II-5 Table C1-1. Forest area per Holdridge forest life 

zone group in the U.S. and U.S.-affiliated tropical 

islands, 2003–2013

II-9 Table C1-2. Percentage of forest area by 

ownership type and jurisdiction, circa 2010

II-10 Table C1-3. Area and percentage of forests in 

protected areas (Gap Status 1 + 2), 2003–2013

II-10 Table C1-4. Forest area under protection or 

 management and prohibition of conversion to 

other land uses, 2003–2013

II-14 Table C1-5. Number of documented species 

and native-forest-associated species for major 

 taxonomic groups in the U.S. Virgin Islands, 

Puerto Rico, and Hawaii (endemism [E] noted 

in parenthesis)

II-15 Table C1-6. Number of terrestrial IUCN Red List 

species native to U.S. and U.S.-affiliated tropical 

 islands per at-risk category
Assessing Forest Sustainability in the Tropical Forests of the United States vii

II-16 Table C1-7. Endangered (E), threatened (T), and 

candidate (C) forest-associated species listed by 

the U.S. Fish and Wildlife Service in Hawaii, 

 Puerto Rico, and the U.S. Virgin Islands in 2010

II-25 Table C2-1. Forest stocking data on U.S.- 

affiliated Caribbean and Pacific islands, 

2004–2013

II-27 Table C2-2. Forest plantation area and percentage 

 of total forest area, circa 2010

II-27 Table C2-3. Planted forest area in Hawaii, 2015

II-28 Table C2-4. Hawaiian nonnative plantation 

 timber inventory summary data, 1999–2000

II-35 Table C3-1. Number of documented invasive 

 terrestrial species in the U.S. tropical islands

II-49 Table C4-1. Water-quality data for five jurisdictions in the Caribbean and the Pacific, 2010

II-54 Table C5-1. Total carbon stocks per island 

jurisdiction

II-55 Table C5-2. Carbon stocks per unit area of forest 

for each island jurisdiction

II-56 Table C5-3. Trends contributing to flux in carbon 

stocks by jurisdiction

II-61 Table C6-1. Demographic information for islands 

 considered in this report

II-63 Table C6-2. Forest products production and use

II-64 Table C6-3. Extent of agroforest in Pacific islands

II-67 Table C6-4. Visitor arrivals, 2000–2010

II-73 Table C7-1. Government institutions responsible 

for forest management activities in the Pacific and 

 Caribbean Islands

II-76 Table C7-2. Sample of academic institutions 

 related to forests and forest management

II-77 Table C7-3. Sample of nongovernmental 

 environmental organizations

II-78 Table C7-4. Participation in U.S. Forest Service 

 programs through 2010

List of Figures

I-3 Figure 1-1. Island jurisdictions considered in this 

report: (A) all, (B) Hawaii, (C) Pacific Islands, and 

(D) Puerto Rico and the U.S. Virgin Islands.

I-21 Figure 3-1. Forest area and percentage of forest 

cover by island jurisdiction.

II-3 Figure C1-1. Forest cover as a percentage of total 

land area for the U.S. and U.S.-affiliated tropical 

islands (2001–2009).

II-4 Figure C1-2. Holdridge Life Zone classification 

 system.

II-5 Figure C1-3. Forested acreage of Holdridge Forest 

Life Zones in the U.S. and U.S.-affiliated tropical 

islands (2001–2009).

II-7 Figure C1-4. Forested lands in the main Hawaiian 

Islands (Conry et al. 2008).

II-8 Figure C1-5. Forest area dominated (>50 percent) 

 by nonstocked, small-, medium-, and large- 

 diameter stand classes (dbh = diameter at breast 

height).

II-11 Figure C1-6. Frequency of forest patches in 

 Puerto Rico in 2000.

II-12 Figure C1-7. Forest patch size in the main 

Hawaiian Islands.

II-13 Figure C1-8. Distribution of land cover by 

jurisdiction.

II-18 Figure C1-9. Current, former and potential 

 distribution of Acacia koa on Hawai ́i Island

II-26 Figure C2-1. Average net volume in cubic feet 

per acre of live trees ≥1 inch diameter at breast 

 height on forest land.

II-39 Figure C3-1. Mean sea-level rise from the period 

1993–2010, ranging from an average of -0.4 inch/

year (blue) to 0.6 inch/year (red).
viii Assessing Forest Sustainability in the Tropical Forests of the United States

Metric Equivalents

When you know: 	 Multiply by: 	 To find:

Inches (in) 2.54 Centimeters

Feet (ft) 0.305 Meters

Miles (mi) 1.609 Kilometers

Acres (ac) 0.405 Hectares

Square miles (mi2) 2.59 Square kilometers

Cubic feet (ft3) 0.283 Cubic meters

Tons 0.9071 Tonnes

City of Charlotte Amalie, capital of the U.S. Virgin Islands.
Assessing Forest Sustainability in the Tropical Forests of the United States I–ix

Assessing Forest Sustainability in the Tropical Forests of the United States

Part I.

Introduction and Summary
Aerial view of Kosrae, Federated States of Micronesia. The sunlit trees at center are the Yela Valley freshwater swamp forest; a Forest 

Legacy conservation easement here protects the largest remaining stand of ka (Terminalia carolinensis) in the world.

Nick Hall, courtesy of The Nature Conservancy
Assessing Forest Sustainability in the Tropical Forests of the United States I–1

Chapter 1

Assessing Forest Sustainability in the Tropical Forests of the United States

Introduction

Guy C. Robertson and Kathleen A. McGinley

The purpose of this report is threefold: (1) most importantly, to present a comprehensive description of the 

current state of tropical forest ecosystems on islands in 

and affiliated with the United States; (2) to construct a 

well-organized compendium of information as a general 

reference for multiple purposes; and (3) to provide our 

own sustainability assessment as a contribution to the 

broader discussion about the crucial question of forest 

sustainability in the U.S. tropical islands.

This report is a companion report to the National Report 

on Sustainable Forests, a periodic Forest Service publication that addresses the sustainability of temperate forests 

of the United States (USDA FS 2011). As in the national 

report, this effort relies on the Montréal Process Criteria 

and Indicators for Sustainable Forest Management (MP 

C&I) as a basis for gathering and organizing information (Montréal Process 2015). In terms of geographical 

and topical scope, this effort is the first of its kind. It is 

designed to provide a first approximation of a sustainability assessment of U.S. tropical forests using the MP C&I, 

and to serve as a baseline for periodic assessments of 

these forests in the future. 

Broadly defined, forest sustainability refers to the ability 

of forest ecosystems to maintain desired characteristics 

and provide desired outputs into the future. The identification and definition of these desired characteristics, however, has proven to be a moving target, especially when 

applied to systems as complex and dynamic as forests. As 

our understanding of forests has grown, we have increasingly come to recognize the many different ways in which 

we rely on and benefit from these ecosystems, and we 

have experienced a commensurate increase in the need for 

information to manage them effectively. Forest assessment 

and planning documents now typically include information on, for example, the plants and animals comprising 

a given ecosystem; physical characteristics, such as soil 

condition and local climate; social and economic aspects 

of nearby communities; timber and nontimber forest products; opinion surveys; recreation activity; atmospheric 

carbon balances; and a host of other elements deemed 

important by different organizations and individuals 

interested in forests and their management. Organizing 

and presenting this vast amount of information, let alone 

using it to inform decisions, is a major undertaking.

The tropical forests considered in this report differ 

considerably from their temperate counterparts found on 

the U.S. mainland, both for their ecological components 

and for the social and economic systems in which they are 

embedded. The Montréal Process indicators, however, are 

flexible enough to be generally applicable to tropical U.S. 

forests, and they are used here to report on biophysical 

characteristics such as forest extent and composition, 

on biological and physical disturbance processes, on the 

unique social and economic conditions prevalent on the 

islands, and on the institutions through which people seek 

to use and protect their forest resources. 

A major challenge in compiling this report has been 

analyzing information from disparate island jurisdictions 

separated by vast distances and exhibiting different 

conditions and histories. This challenge extends to data 

acquisition and consolidation, and the central policy 

recommendations of the report focus on improving data 

development and consistency. One of the first steps in this 

process is to identify currently available data sources, 

and the report explicitly addresses the “meta-questions” 

surrounding data generation and use.

The Islands

Nine specific island jurisdictions are treated in this report. 

Hawaii is the only state. The other jurisdictions are 

affiliated with the United States in various ways. From 

east to west, they are:

• U.S. Territory of the Virgin Islands (USVI)

• Commonwealth of Puerto Rico

• State of Hawaii

• Territory of American Samoa

• Republic of the Marshall Islands

• Federated States of Micronesia (FSM)

• Commonwealth of the Northern Mariana Islands

• Territory of Guam

• Republic of Palau

These islands represent some of the most distinctive 

ecological and social systems to be found in the United 

States. The ecological richness and number of endemic 

species in Hawaii, for example, are world famous. The 

agroforestry practices of native cultures in the South 

Pacific exemplify a long and unique history of close 

interaction between humans and nature. And the history 

of European colonization in the Caribbean, with its 
I–2 Assessing Forest Sustainability in the Tropical Forests of the United States

Table 1-1. Characteristics of island jurisdictions considered in this report

Island jurisdictions Total area Political status

Islands

Population 

(2010)

Permanently 

inhabited Other

Acres 

(hectares)

Caribbean:

U.S. Virgin Islands 85,760

(34 706)

Territory 4 50 islands and cays 106,405

Puerto Rico 2,199,901

(890 270)

Commonwealth 3 3+ 3,725,789

Pacific:

Hawaii 4,127,337

(1 670 277)

State 7 Kahoolawe + 

9 northwestern 

islands/atolls + 

130 small islands

1,360,301

American Samoa 49,280

(19 943)

Territory 5 islands + 

Swain’s Atoll

Rose Atoll 55,519

Guam 135,680

(54 908)

Territory 1 159,358

Republic of the Marshall Islands 44,800

(18 130)

Nation 20 atolls 

+ 4 islands

9 atolls + 

Jemo Island

67,182

Federated States of Micronesia 149,804

(60 624)

Nation with 

 four states

Up to 77 

inhabited islands

542 islands 

and atolls

102,843

Commonwealth of the 

 Northern Mariana Islands

113,280

(45 843)

Commonwealth 3 12 northern islands 53,883

Republic of Palau 114,560

(46 361)

Nation with 

 16 states

7 islands + 

Kayangel Atoll

250, including 

“Rock Islands”

20,956

introduction of new land use patterns and biological 

agents, profoundly shapes current ecological conditions in 

the region in very specific ways. 

Given the wide dispersal of the islands across two hemispheres, and their unique histories and ecologies, it is an 

open question as to whether the inclusion of all the islands 

in a single report is justified. Indeed, this question challenged the authors of this report, and will likely challenge 

readers as well. Still, a number of key characteristics are 

shared to a greater or lesser degree by all the islands. In 

contrast to the vast majority of the mainland United States 

where a temperate climate is the norm, these islands all 

possess tropical forests characterized by high and relatively stable temperatures. Also, they are all subject to the 

various influences of island geography, including relative 

isolation, restricted home ranges for native plants and 

animals, the biological abundance of nonnative species, 

and socioeconomic characteristics that set them well apart 

from mainland U.S. culture (see MacArthur and Wilson 

[1967] and Whittaker and Fernández-Palacios [2017] for 

indepth discussions of island biogeography). An important 

question for this study is whether, by assessing them side 

by side, we can identify similarities across the islands as 

well as contrasts between them. 

In tables or similar listings, the island jurisdictions are 

presented in this report in order from east to west unless 

otherwise indicated by the information or topics being 

considered. This allows for grouping along the major 

geographic breakpoints: the Caribbean, Hawaii, and the 

U.S.-affiliated Pacific. We have generally maintained 

similar groupings in our discussion and analysis sections, 

but this was not always possible. 

The tropical Pacific islands are generally divided into 

three geographic/cultural regions called Melanesia, Polynesia (which includes the Hawaiian and Samoan archipelagoes), and Micronesia (which includes the Marshall 

Islands, Mariana Islands, and Caroline Islands). Note that 

political jurisdictions do not always align with geographic 

designations. The Samoan archipelago includes independent Samoa, which is not affiliated with the United States; 

likewise, the Virgin Islands archipelago includes the 

British Virgin Islands, which are east of the USVI. The 

Mariana chain includes Guam (the southernmost island) 

and the Commonwealth of the Northern Mariana Islands. 

The Caroline Islands include Palau and the FSM. Basic 

characteristics of the nine jurisdictions are shown in table 

1-1, and the island locations are shown in figure 1-1.
Assessing Forest Sustainability in the Tropical Forests of the United States I–3

Figure 1-1. Island jurisdictions considered in this report: (A) all, (B) Hawaii, (C) Pacific Islands, and (D) Puerto Rico and 

the U.S. Virgin Islands.

A
I–4 Assessing Forest Sustainability in the Tropical Forests of the United States

Figure 1-1. Continued.
Assessing Forest Sustainability in the Tropical Forests of the United States I–5

Table 1-2. Montréal Process Criteria and Indicators criterion summary

Criterion name Description

1. Conservation of biological diversity Nine indicators describing the biophysical characteristics of forests, including forest 

extent, composition, diversity of flora and fauna. Conservation efforts also covered.

2. Maintenance of productive capacity 

of forest ecosystems

Five indicators describing forest productive capacity, area of planted forests, and 

current production levels of forest outputs (timber and nontimber). 

3. Maintenance of forest ecosystem 

health and vitality

Two indicators describing (1) biotic forest disturbance processes (e.g., insects and 

diseases), and (2) abiotic disturbance processes (e.g., fire and drought).

4. Conservation and maintenance of 

soil and water resources

Five indicators describing forest soils and water conditions along with efforts to 

conserve them.

5. Maintenance of forest contribution 

to global carbon cycles

Three indicators describing (1) forest carbon pools, (2) carbon pools in long-lived forest 

products, and (3) avoided carbon emissions from using wood to produce energy.

6. Maintenance and enhancement of 

long-term multiple socioeconomic 

benefits to meet the needs of societies

Twenty indicators describing (1) the production and consumption of forest products, 

(2) investments in the forest sector and related human capital, (3) forest employment 

and community conditions, (5) forest-based recreation and tourism activity, and 

(5) cultural and spiritual values associated with forests.

7. Legal, institutional, and economic 

framework for forest conservation 

and sustainable management

Ten indicators describing legal and institutional arrangements for forest planning 

and management, public participation mechanisms, economic incentives, and 

monitoring efforts.

The wide dispersion of island jurisdictions, particularly in 

the Pacific, is immediately apparent in figure 1-1. Another 

geographic characteristic worth noting is that spatial 

arrangement differs considerably across jurisdictions, with 

Puerto Rico at one extreme, possessing a relatively large 

contiguous land mass on the main island, and Micronesia 

at the other, with a small amount of total area distributed 

across literally hundreds of islands and atolls spanning a 

considerable longitudinal arc. This geographic heterogeneity is mirrored in the different political characteristics 

of the jurisdictions (ranging from U.S. statehood to freely 

associated nations), which in turn result in different data 

reporting conventions and different forest management 

arrangements. Demographics likewise range from large 

and highly concentrated urban populations in Puerto Rico 

and Hawaii (in Honolulu at least), to small and dispersed 

rural or semi-rural settlements in the U.S.-affiliated 

Pacific. Social and economic conditions also differ considerably across the islands. 

The Montréal Process Criteria 

and Indicators

The Montréal Process Criteria and Indicators for Sustainable Forest Management (MP C&I) are the framework 

by which data are organized in this report. Other C&I 

frameworks would likely serve as well, but the MP C&I 

do have several advantages in this application: (1) they 

are firmly established; (2) they are comprehensive in 

scope and allow for flexible application; and (3) they are 

consistent with U.S. forest sustainability reporting at 

the national level. The MP C&I were first instituted in 

the 1990s as a response to growing concerns about the 

sustainability of the world’s temperate and boreal forests 

(Montréal Process 2015). Twelve countries, including 

the United States, voluntarily participate in the Montréal 

Process through the application of the MP C&I to assess 

their respective forest resources and through periodic 

meetings to review and adjust the C&I and coordinate 

reporting activities. The process for C&I formulation and 

adjustment is based on the consensus of participating 

countries, and the result is a comprehensive list of forest 

ecosystem characteristics, and related socioeconomic 

characteristics, deemed important by member countries 

and applied in a flexible fashion in accordance with the 

resource conditions and reporting preferences of each. 

Other C&I that are specifically tailored to tropical forests 

exist, notably those produced by the International Tropical 

Timber Organization (ITTO 2005), but the vast majority 

of MP indicators are equally applicable to temperate and 

tropical forests. The use of the MP C&I in this report has 

the added benefit of allowing more direct comparison with 

the National Report on Sustainable Forests.

The current version of the MP C&I contains 54 indicators arranged under 7 criteria (table 1-2). The first five 

criteria address the biophysical characteristics of forests 

and rely heavily on data generated by forest inventory 
I–6 Assessing Forest Sustainability in the Tropical Forests of the United States

and monitoring activities. The sixth criterion contains 

20 indicators and is essentially a catch-all criterion for 

social and economic aspects of forests and their related 

human systems. Criterion 6 relies primarily on social and 

economic statistics generated outside of the forest sector. 

Criterion 7, the last criterion, addresses policy and institutional arrangements for forest planning, management, and 

monitoring, and the indicators in this criterion are treated 

mainly through qualitative description. 

Taken together, the seven criteria and 54 indicators of the 

MP C&I can be viewed as an attempt to provide a detailed 

definition of forest sustainability. More to the point, they 

provide a useful framework for organizing the various 

pieces of information necessary to assess forest sustainability. Exactly what to do with this information once it 

is gathered and presented, however, remains an essential 

question. Various systematic modelling approaches to 

sustainability assessment using C&I have been attempted 

over the years (see Singh et al. 2009 for a useful survey of 

this work), but generally these efforts are most successful 

when applied to relatively narrow sustainability problems. 

Comprehensive assessments of forest sustainability 

across ecological, social, and economic dimensions are 

less amenable to this sort of technique. Similarly to the 

national report, we take a more qualitative approach, 

presenting available data for the indicators, then summarizing those data and identifying key findings with the 

aim of informing broader public discussions of sustainability rather than producing a definitive or quantitative 

determination of whether forests are sustainable. 

The MP C&I present a daunting set of data requirements, 

but many of the indicators are best viewed as data 

placeholders to remind us of the information still needed 

to provide a complete assessment of forest ecosystems 

and their sustainability. Fully populating the MP C&I 

with quantitative and definitive information is a practical 

impossibility. This is true for the national report, and, 

given the relative scarcity of information available for the 

U.S. tropical islands, it is even more so for this report. For 

certain indicators, particularly those that rely on forest 

inventory data, we have good information. In other areas, 

such as indicators related to forest health or socioeconomic conditions, our information is mostly anecdotal or 

absent. Though this situation is far from satisfactory, the 

indicators in this latter category serve a useful purpose 

in reminding us of important gaps in our data and our 

understanding.

Roadmap to the Report

This report is divided into two main parts. In Part I, this 

introductory chapter is followed by a chapter describing 

the data used to produce the report. Designed primarily 

for analysts, this “data chapter” identifies major data 

sources, their periodicity, and their application to tropical 

islands. Part I concludes with a chapter summarizing key 

findings and major policy recommendations based on the 

C&I information provided in Part II as well as the data 

reporting arrangements identified in the data chapter.

Part II comprises the bulk of the report and contains seven 

chapters addressing each of the seven criteria of the MP 

C&I. The first four chapters of Part II generally follow 

the MP framework, addressing each indicator in turn 

(at least in those instances in which adequate data are 

available). Owing to a lack of data or applicability in the 

island context, criteria 5 (carbon), 6 (social and economic 

aspects), and 7 (institutional framework) are addressed in 

a more abbreviated fashion. In these chapters, we simply 

try to present useful information addressing the criteria 

but generally bypass the MP indicator framework.

Literature Cited

International Tropical Timber Organization [ITTO].

2005. Revised ITTO criteria and indicators for the sustainable management of tropical forests including reporting format. Policy development series 15. Yokohama, 

Japan. 40 p. http://www.itto.int/direct/topics/topics_

pdf_download/topics_id=9630000&no=1&disp=inline. 

(March 2017).

MacArthur, R.H.; Wilson, E.O. 1967. The theory of 

island biogeography. Princeton, NJ: Princeton University 

Press. 224 p.

Montréal Process. 2015. Criteria and indicators for the 

conservation and sustainable management of temperate 

and boreal forests. 5th ed. 31 p. http://www.montrealprocess.org/documents/publications/techreports/MontrealProcessSeptember2015.pdf. (September 2016).

Singh, R.K.; Murty, H.R.; Gupta, S.K.; Dikshit, 

A.K. 2009. An overview of sustainability assessment 

methodologies. Ecological Indicators. 9: 189–212.
Assessing Forest Sustainability in the Tropical Forests of the United States II–7

U.S. Department of Agriculture, Forest Service 

[USDA FS]. 2011. National report on sustainable forests—2010. FS-979. Washington, DC: U.S. Department 

of Agriculture, Forest Service. 212 p. http://www.fs.fed.us/

research/sustain/. (September 2016).

Whittaker, R.J.; Fernández-Palacios, J.M. 2017. Island 

biogeography: ecology, evolution, and conservation. 2nd

ed. Oxford, United Kingdom: Oxford University Press. 

416 p. http://www.thewflc.org/islandforestry/fsm.pdf. 

(September 2016).
A tropical rain forest timber stand improvement operation (circa 1960) on the El Yunque National Forest, Puerto Rico, in which 

undesirable trees were poisoned or marked for removal, desirable trees were marked to retain for the future crop; and records 

were kept of tree growth to learn the effect of improvement methods.

USDA Forest Service
Assessing Forest Sustainability in the Tropical Forests of the United States I–9

Chapter 2

Assessing Forest Sustainability in the Tropical Forests of the United States

Description of Available Data

Guy C. Robertson and Kathleen S. Friday

Introduction

Information provides the foundation for assessment. 

Forest sustainability assessments must treat a broad range 

of indicators across ecological, social, and economic 

domains, often with relatively few resources to devote to 

primary data collection. As a result, these assessments 

must rely on various established data streams to populate 

their respective indicators with useful information. This 

was certainly the case for the mainland assessment 

provided in the National Report on Sustainable Forests—

2010 (USDA FS 2011b), and it is also true for this report. 

An assessment of available data and reporting mechanisms speaks to our ability to understand, manage, and 

conserve island forests, so it is an important sustainability 

measure in its own right. Moreover, sustainability assessments such as this report usually do not exist in isolation; 

there are various other reporting mechanisms and requirements in which the island entities considered in this report 

are engaged. To make the best use of the scarce resources 

at hand and enhance the value of all reporting efforts, it is 

important to clearly identify key data sources and coordinate reporting activities so that these activities support 

each other while avoiding costly duplication of efforts. 

The objective of this chapter is to identify (1) the key data 

sources that help inform sustainable forest management 

in the U.S. tropics and (2) the key reporting activities that 

the tropical islands are conducting. These resources are 

listed in tables 2-1 and 2-2 and are further described in 

subsequent sections of this chapter. 

Primary Data Sources

As is true in forest reporting on the U.S. mainland, forest 

inventory data forms the backbone of forest sustainability 

reporting for the tropical islands, particularly in regard 

to biophysical characteristics of forest ecosystems. In 

the continental United States, the Forest Service’s Forest 

Inventory and Analysis (FIA) program provides much of 

this information, and the FIA has begun expanding its 

activities to cover the U.S. tropics. Additional data collection efforts provide information on forest species, forest 

health issues (e.g., forest pests, invasive species, and forest 

disturbance events), and the extent and nature of forest 

cover. In the socioeconomic domain, major reporting 

mechanisms such as the U.S. Census and the products of 

other U.S. Department of Commerce bureaus provide data 

that extend well beyond the purview of the U.S. Forest 

Service or local forest agencies but that are nonetheless 

essential to understanding the social and economic 

dimensions of forest sustainability. Various other sources 

provide statistics on economic, environmental, and social 

conditions. 

Although coverage from the main statistical sources 

identified in table 2-1 is generally uniform for the 

continental United States, the same cannot be said for 

the tropical islands. Much of this owes to their differing 

status, ranging from statehood (i.e., Hawaii) to free 

association (e.g., Federated States of Micronesia), meaning 

that even such standard statistical efforts as the U.S. 

Census are not evenly applied. Likewise, their distant 

locations and island topography (Palau, for example, has 

more than 300 small islands) make ecosystem sampling 

such as is undertaken by FIA an expensive and technically 

challenging proposition. Coverage in regard to land use 

and characteristics is spotty and difficult to analyze in a 

consistent fashion, although, for FIA at least, the situation 

has been improving.

Forest Service Inventory and 

Analysis Program 

The FIA program has been in operation for more than 80 

years and constitutes the principal source of information 

on U.S. forests and the trees that comprise them. It was a 

primary resource for the National Report on Sustainable 

Forests, without which that report would not have been 

possible. FIA relies on on-the-ground sampling of forest 

plots to develop statistical reports on forest conditions. 

The inventory is applied on a uniform basis to all forested 

areas in the United States and its territories to develop 

statistical measures that are consistent across time and 

space and can be assessed at multiple spatial scales, 

including U.S. counties. The information provided from 

base sample plots (so-called “phase 2 plots”) includes 

forest area, ownership, tree species counts, wood 

volumes, forest growth and removals, tree diameter 

class (size), tree mortality, and forest carbon mass and 

biomass. Although the inventory is primarily focused on 
I–10 Assessing Forest Sustainability in the Tropical Forests of the United States

Table 2-1. Data sources for assessing tropical forest sustainability in U.S. territories

Program Agency Description

Forest Inventory and Analysis (FIA) U.S. Forest Service FIA conducts plot-based sampling of forest cover, species 

composition, and other characteristics. In the Caribbean, this 

work is jointly funded and conducted with the International 

Institute of Tropical Forestry. Plots are revisited on a periodic 

basis with the aim of providing a statistically consistent 

representation of forest extent and conditions for a given 

geographical area. The ability to address smaller spatial 

scales is limited by sampling intensity.

Vegetation surveys and mapping U.S. Forest Service In the 1980s, the Pacific Southwest Research Station mapped 

vegetation types using aerial photography for nearly all 

high islands of the U.S.-affiliated Pacific, with the notable 

exceptions of Hawaii and Guam. In the 2000s, the Pacific 

Southwest Region State and Private Forestry program began 

to assist Pacific state foresters with vegetation type maps on 

a regular basis.

U.S. endangered species listings U.S. Fish and Wildlife 

Service

Provides the names, numbers, and descriptions of all federally 

listed threatened and endangered animal and plant species, 

including those found in politically affiliated jurisdictions. 

Additional information on conservation needs and efforts 

also is made available. 

IUCN Red List of Threatened Species International Union for 

the Conservation of 

Nature (IUCN)

Provides the names, conservation status, and descriptions of 

globally threatened animal and plant species as determined 

and periodically reviewed by experts based on globally 

agreed assessment criteria.

Global Invasive Species Database 

(GISD) 

Invasive Species Specialist 

Group (ISSG), organized 

by the IUCN Species 

Survival Commission

The ISSG is a global network of scientific and policy experts 

focused on invasive species. It manages the GISD as an online 

resource of information on invasive species, their ecology, 

spread, management, and effects.

U.S. Census U.S. Census Bureau Provides total population and assorted demographic and 

economic statistics based on the decadal U.S. Census. 

Additional demographic and economic statistics information 

are provided through community sampling efforts.

Various economic statistics collected 

by U.S. federal agencies

Bureau of Labor Statistics, 

Bureau of Economic 

Analysis, etc.

Assorted statistics on employment, production, and trade.

Various local and regional data 

reporting activities

State-level agencies or 

equivalent

Tourism visitation rates. Assorted economic, social, and 

environmental statistics.

forestry measures for growth and volume, augmented 

sampling of a subset of the base plots (“phase 3 plots”) 

has expanded the survey’s reach into categories that track 

forest health conditions and related characteristics (for 

information regarding FIA sampling procedures, see 

Bechtold and Patterson 2005). In the past, FIA provided 

periodic inventories that described conditions as sampled 

for a given state in a given year or pair of years, then 

moved on to the next state. In the past decade, FIA has 

switched to an annualized inventory for U.S. states, using 

continuous sampling across all states except Hawaii. U.S. 

jurisdictions in the Pacific remain on a periodic inventory, 

however, while those in the Caribbean are sampled 

continuously but reported periodically.

FIA activity and status for the tropical islands are shown 

in table 2-3. Inventories have been completed within the 

past decade for all the islands, and subsequent inventories 

for all are scheduled over the next 5 years (note that the 

“Year of Inventory” columns in the table denote the 

year in which the inventory activities are locked down 

for statistical purposes, not the year in which the data 

are compiled, analyzed, and presented). Reports have 

been published for the first set of completed inventories, 

and current data are available through the FIA website 

referenced above. As on the mainland, phase 3 plots in 

the Pacific are sampled on an “ala carte” basis determined 

in part by FIA client needs; islands are allowed to choose 

certain of the variables to be measured. This allows 
Assessing Forest Sustainability in the Tropical Forests of the United States I–11

Table 2-2. Forest reporting activities engaged in by U.S. tropical islands

Program Agency Description

Global Forest Resource 

Assessment (GFRA)

U.N. Food and Agriculture 

Organization

Compiles forest statistics for countries around the globe. Relies 

on submissions by individual countries and does not generate its 

own statistics.

Statewide Assessments 

and Resource Strategies 

(SWARS), subsequently 

called Forest Action Plans

State or comparable level The Cooperative Forestry Assistance Act, as enacted in the 2008 Farm 

Bill, required each state to develop SWARS reports by 2010. The 

assessments of forest resources provided analyses of forest conditions 

and trends, and delineated priority forest landscape areas for investing 

Forest Service State and Private Forestry funds and other resources. 

National Forest Health 

Monitoring

U.S. Forest Service Annual Forest Health Highlights summarize forest health conditions, 

and are published at regular intervals (generally annually) for the 

Pacific Islands.

Table 2-3. Forest Inventory and Analysis inventory status in tropical islands

Jurisdiction

Year(s) of 

completed 

inventory

Year of last 

published 

report

Year(s) of 

next 

inventory

Total 

Phase 2 

plots

Total 

Phase 3 

plots

Online 

data

Caribbean:

Puerto Rico 1980, 1985 

(partial update), 

1990, 2003, 2009

2013 Periodic,

2014

373 61 Yes

U.S. Virgin Islands 2004, 2009 2013 2014 73 40 Yes

Pacific:

Hawaii Periodic, 

2010–2015

Not yet

published

Periodic, 

2017–2020

Planned: 

500

— No

American Samoa 2001, 2012 2004 2022 21 — Yes

Republic of the Marshall Islands 2008 2011 2018 44 — Yes

Federated States of Micronesia 2005–2006 2011 2016 73 — Yes

Commonwealth of the 

 Northern Mariana Islands

2004,

2015

2011 2025 35 — Yes

Guam 2002, 2013 2004 2023 46 — Yes

Republic of Palau 2003, 2014 2007 2024 54 — Yes

— = not available. 

Source: USDA FS (2011b: table 10), updated by authors.

for the flexible inclusion of some variables (understory 

vegetation and tree crowns in the case of the Pacific 

islands) and the omission of others (soils, lichens, ozone, 

and down woody debris). Local entities have the option 

of further increasing the number of phase 3 plots through 

cost-sharing agreements with the Forest Service. 

For forest inventory activities, however, the geography of 

the islands presents several challenges that are not easily 

overcome. From a statistical standpoint, the heterogeneity 

of many of these places, with their numerous islands 

of varying sizes and conditions, means that statistical 

averages derived from the inventory will be subject to 

wide error bounds and may not be all that representative 

of actual conditions on the ground (although this 

problem will be much more important in some places 

than in others). And, from a practical standpoint, the 

island topography and remote location of many places, 

especially in the Pacific, make the establishment and 

repeated sampling of plots a difficult and costly endeavor. 

This is compounded by the fact that actual forest areas 

being sampled are quite small, so significant resources 

must be expended to inventory a relatively small amount 

of forest. These issues all point to the fact that islands 

constitute a very different operating environment than 

the continental land mass for which FIA, and similar land 

inventories, was designed. That said, FIA still stands as a 

valuable data source for understanding tropical forests in 

the islands, and discussions are underway as to how this 

source may be augmented or adjusted to better fit local 

needs. 
I–12 Assessing Forest Sustainability in the Tropical Forests of the United States

Other Sources of Ecological Data

Various other sources provide information on ecological 

conditions of forests in the tropical islands. Some of 

these are specific to individual territories, but the sources 

listed here apply to all islands included in this report or 

regional aggregations thereof (i.e., islands in the Pacific 

or the Caribbean). In many cases, the challenges related 

to island topography and remoteness listed for FIA above 

also apply. 

U.S. Forest Service Pacific Southwest Region “Pacific

Imagery Consortium Vegetation Mapping and Monitoring” (PICVM). Using satellite imagery as its primary 

data source, this project provides vegetation maps for 

Hawaii and the Pacific Islands territories (table 2-4). 

Vegetation type classification is not necessarily consistent 

with earlier maps or between islands. Maps, analysis, and 

background information are available from the Forest 

Service’s Pacific Southwest Region State and Private 

Forestry unit at https://www.fs.usda.gov/detailfull/r5/forest-grasslandhealth/?cid=fsbdev3_046690&width=full). 

U.S. Forest Service Forest Health Highlights. The 

Forest Service’s national Forest Health Monitoring (FHM) 

program is designed to determine the status, changes, and 

trends in indicators of forest condition on an annual basis. 

FHM uses data from ground plots and surveys, aerial 

surveys, and other biotic and abiotic data sources and 

develops analytical approaches to address forest health 

issues that affect the sustainability of forest ecosystems. 

FHM’s Forest Health Highlights reports are usually 

released annually for Hawaii and the U.S.-affiliated 

Pacific islands collectively, and the Forest Service plans 

to release reports for the Caribbean islands in the future. 

Current and historical highlights may be found at http://

www.fs.fed.us/foresthealth/fhm/fhh/fhmusamap.shtml.

U.S. Fish and Wildlife Service Threatened and 

Endangered Species Listings. The listing process uses a 

candidate assessment approach to identify threatened and 

endangered (T&E) species and assign them conservation 

priorities and associated legal protections. The assessment 

process is targeted to individual species and relies on 

multiple information sources (state agencies, university 

Table 2-4. Vegetation type mapping status in tropical islands

Jurisdiction Year(s) of imagery Report/publication Vegetation data package

Caribbean:

U.S. Virgin Islands Circa 2000 Kennaway et al. 2008 http://data.fs.usda.gov/geodata/

rastergateway/caribbean/index.php 

Puerto Rico Circa 1991, 2000, 2003 Gould et al. 2008, 

Kennaway et al. 2007 

http://data.fs.usda.gov/geodata/

rastergateway/caribbean/index.php 

Pacific:

Hawaii

American Samoa 1984 Cole et al. 1988 FIA

Republic of the Marshall Islands 2008 PICVM

2003–2004 Liu and Fischer 2007 PICVM

2010–2011 PICVM

Federated States of Micronesia 1975-1976 Falanruw et al. 1987, 

MacLean et al. 1986, 

Whitesell et al. 1986

FIA

2006–2010 PICVM

Commonwealth of the 

 Northern Mariana Islands

1976 Falanruw et al. 1989 FIA

2006 Liu and Fischer 2006 PICVM

Guam 2005–2006 PICVM

2011–2014 Liu and Fischer 2014 PICVM

Republic of Palau 1976 Cole et al. 1987 FIA

2005–2006 PICVM

PICVM = Pacific Imagery Consortium Vegetation Mapping and Monitoring.

Forest Inventory and Analysis (FIA) digitized maps from the 1980s.
Assessing Forest Sustainability in the Tropical Forests of the United States I–13

studies, etc.). NatureServe (http://www.natureserve.org) is 

a primary data source providing ongoing tracking of T&E 

species, but its extension to the tropics beyond Hawaii is 

limited to Latin America and the Caribbean through its 

sister database “InfoNatura” (http://infonatura.natureserve.org/). Note that these data sources focus on species 

as the unit of analysis and not on geographic units (in 

contrast to FIA or the U.S. Census).

IUCN Red List of Threatened Species. The International Union for the Conservation of Nature (IUCN) 

maintains threatened species listings similar to those kept 

by the U.S. Fish and Wildlife Service, but compiled at 

the international level and involving somewhat different 

criteria for listing. Groups responsible for the nomination 

and review of listings include BirdLife International, the 

World Conservation Monitoring Centre, and the IUCN 

Species Survival Commission, among many others. Here 

again, species are the unit of analysis and not geographic 

units.

Global Invasive Species Database (GISD). Managed by 

the IUCN, the GISD tracks invasive species by geographic 

area. The database is searchable by location and can be 

found at http://www.issg.org. The purpose of the GISD 

is to share descriptive information on identified species 

where available rather than to quantify the occurrence of 

invasive species for geographic localities. So the number 

of species listed in the GSID serves as a general indicator 

but not as a statistical sample of invasive species activity.

Sources for Socioeconomic 

Information

Socioeconomic information for the tropical islands is 

generally available through standard government reporting activities, such as those of the Census Bureau (CB) 

and other branches of the U.S. Department of Commerce. 

However, because the territories differ in their legal 

status, coverage is not uniform across all the islands, and 

time series are less well developed than for U.S. states. 

Additionally, many of the trade statistics produced for 

the national report are reported at the national or customs 

district level and cannot be replicated for individual island 

territories. In many cases, reporting of socioeconomic 

data for island territories (excluding Puerto Rico and 

Hawaii) appears to be ad hoc, and measures are not 

included in the standard statistical tables presented for 

U.S. states. The U.S. Department of the Interior’s Office 

of Insular Affairs provides an excellent compilation of 

statistics for territories and freely associated states (once 

again excluding Puerto Rico and Hawaii) at http://www.

doi.gov/oia/. 

U.S. Department of Commerce Census Bureau. 

Performs a decadal census for U.S. states and territories. 

The 2010 census includes Puerto Rico and Hawaii. More 

limited coverage is provided on a different schedule for 

American Samoa, the Northern Marianas, Guam, and 

the U.S. Virgin Islands. Besides demographic statistics, 

the CB provides many economic indicators, including 

regional income measures. The freely associated states 

(Federated States of Micronesia, Republic of the Marshall 

Islands, and Republic of Palau) are omitted from regular 

U.S. Census reporting and rely on local efforts to produce 

demographic information.

U.S. Department of Commerce Bureau of Economic 

Analysis (BEA). The BEA estimates gross domestic 

product statistics for states and U.S. territories 

(but not for freely associated states).

Regional Studies and Data 

Reporting Activities

The tropical islands engage in several periodic data 

reporting activities and have commissioned numerous 

one-time reports addressing various forest-related issues. 

These range from repeated estimates of tourism visitation 

rates to special studies on topics such as subsistence use 

or the effects of nonnative species. The information and 

analysis produced are often quite detailed, being focused 

on specific areas of interest, but are rarely consistent 

with data presented for other areas or at other times for 

the same area. Consequently, these studies represent an 

important resource for understanding conditions in particular locations, but they present challenges when trying 

to compile results for broader regions (e.g., the Pacific or 

Caribbean) or timespans. 

Statistical Compilations and 

Related Reports

Whether addressing environmental conditions or socioeconomic conditions, many special studies and periodic 

reports will overlap with forest sustainability reporting. 

Two reports, the Global Forest Resources Assessment 

(GFRA) and the Statewide Assessment and Resource 

Strategies (SWARS), stand out as particularly important 

because they explicitly cover forests and their management, are (or will be) published on a periodic basis, and 

are produced by all the geographic units considered in 

this report. The significance of these two reports extends 

beyond merely providing a consistent data source for 

sustainability reporting. Given their respective scopes, 

the overlap between them, and the need to produce them 
I–14 Assessing Forest Sustainability in the Tropical Forests of the United States

repeatedly, they present an opportunity to efficiently 

consolidate and expand reporting activity through integration, a topic that is addressed more fully in the policy 

recommendations below.

The FAO GFRA

Every 5 years, the United Nations Food and Agriculture 

Organization (FAO) compiles forest statistics from all the 

countries in the world to produce the GFRA, a census 

of forest conditions and extent. The most recent edition 

was produced in 2016 (FAO 2016). Besides the main 

report, the GFRA includes country-specific reports, each 

composed of brief descriptions of forest conditions in the 

given country, followed by data tables and notes as to definitions, data sources, and the derivation of each table (see 

table 2-5 for a listing of GFRA tables and their coverage 

among the island jurisdictions considered here). 

The 17 tables stipulated for use in the GFRA country 

reports cover a range of topics broadly commensurate 

with those covered by the Montréal Process Criteria and 

Indicators (MP C&I), but most countries do not report out 

on every table. Eight of the nine island entities covered in 

this report provided data for GFRA (Hawaii was incorporated in the U.S. country report), relying almost exclusively on FIA data to populate the tables. As a result, the 

information available in their specific country reports is 

weighted to the type of data provided by forest inventories 

and the FIA in particular, and the reports are generally 

weak in their social, economic, and institutional areas. 

Although GFRA country reports for U.S. territories serve 

mainly as a window to already available FIA data, they 

do have the virtue of packaging these data in a consistent, 

easily accessible, and fully documented fashion on a regular basis. Moreover, the 17 GFRA country tables provide 

a ready framework for expanding quantitative reporting 

on forest conditions. (See http://www.fao.org/forestry/

fra/en/ for the GFRA main report, country reports, and 

associated information.)

Statewide Assessment and 

Resource Strategies

As stipulated in the 2008 Farm Bill (P.L. 110-246), all 

U.S. states and territories were required to produce a 

SWARS report by 2010 to qualify for assistance through 

the U.S. Forest Service’s State and Private Forestry 

division. These assessments and strategies, subsequently 

Table 2-5. Summary of data tables provided in FAO 2010 Global Forest Resource Assessment 

(GFRA) country reports

Tables included in country reportsa

GFRA table number and title PR USVI AS RMI FSM CNMI GU RP

 T1. Extent of forest and other wooded land X X X X X X X X

 T2. Forest ownership and management rights X

 T3. Forest designation and management X X X X X X X

 T4. Forest characteristics X X X X X X

 T5. Forest establishment and reforestation

 T6. Growing stock X X X X X X X X

 T7. Biomass stock X X X X X X X X

 T8. Carbon stock X X X X X X X X

 T9. Forest fires

T10. Other disturbances affecting forest health and vitality X X X X X X

T11. Wood removals and value of removals

T12. Nonwood forest products removals and value of removals

T13. Employment

T14. Policy and legal framework X

T15. Institutional framework

T16. Education and research

 T17. Public revenue collection and expenditure

a

 Data for Hawaii are subsumed in the U.S. GFRA country report.

FAO = United Nations Food and Agriculture Organization; PR = Puerto Rico; USVI = U.S. Virgin Islands; AS = American Samoa; 

RMI = Republic of the Marshall Islands; FSM = Federated States of Micronesia; CNMI = Commonwealth of the Northern Mariana Islands; 

GU = Guam; RP = Republic of Palau.

Source: FAO 2010.
Assessing Forest Sustainability in the Tropical Forests of the United States I–15

called “forest action plans” by the Forest Service and the 

National Association of State Foresters, can be found at 

http://www.forestactionplans.org/.

All the island entities considered in this report have 

completed assessment reports, each of which represents a 

considerable accomplishment and a valuable information 

resource. Updates will be required by 2020. 

In contrast to the FAO GFRA data tables, the statewide 

assessments allow for an open-ended approach, with 

format and issues to be chosen by each state or territory 

respectively. The resulting reports often total well over 

100 pages and include a wealth of information not only 

on forest conditions, but on the local economy, social 

conditions, and the principal concerns and desires of 

local residents regarding their forests. Although difficult 

to compare over time or space, the resulting narratives 

provide a depth of understanding of local forests and 

people that is wholly lacking in the FAO GFRA tables 

and impossible to convey in a summary study such as 

this report. 

Conclusions and 

Recommendations

Much of the information required for comprehensive 

forest sustainability reporting is hard to find and compile 

even for the continental United States, a region that possesses some of the best environmental and social statistics 

and analyses in the world. By and large, U.S. tropical 

islands possess nowhere near the same information infrastructure, and this lack is further compounded by their 

island geographies, where heterogeneity makes comparison difficult and isolation makes measurement expensive. 

Noted data gaps include basic forestry information such as 

the distribution of species, and even forest types, as well 

as the prevalence of nonnative species (a pressing problem 

in the Pacific Islands) or the distribution of rare flora and 

fauna. On the social front, much of our understanding of 

the relationships between people and forests is based on 

anecdotal information, where it exists at all, and in regard 

to institutions we have yet to devise adequate measures, 

much less populate them with relevant data, even though 

we know that institutions are crucial to securing sustainable forest management. 

These gaps and weaknesses notwithstanding, there are 

several promising developments in terms of forest sustainability reporting in the U.S. tropics. The FIA program 

is institutionalizing its activities throughout the islands, 

augmented by new remote-sensing-based mapping techniques. Repeated sampling through FIA will increasingly 

allow us to track changes in forest area and composition, 

an essential element in forest sustainability reporting. 

Lists of threatened species and invasive pests and weeds 

are being compiled and consolidated under the auspices of 

federal agencies and the IUCN. Socioeconomic statistics 

are being gathered by the CB and BEA, and one can hope 

that these will improve in the future. And finally, the need 

for information describing forest ecosystems and their 

social dimensions is increasingly recognized, as indicated 

by the content of the FAO GFRA tables and the statewide 

assessments.

The information that does exist, however, is often fragmented and difficult to access. A central objective of this 

report (and of the MP C&I, for that matter) is to bring this 

information together and present it in an easily digestible 

format. The two other comprehensive reporting functions 

identified in this section, the FAO GFRA and statewide 

assessments, serve a similar purpose, and it makes sense 

to consolidate these reporting activities by using the 

GFRA tables as the database, the statewide assessments 

for expanded narratives and priority setting, and regional 

sustainability reporting for summarizing across island 

entities. Specific recommendations for such a consolidation could include:

• Identify currently unaddressed FAO GFRA table 

elements as candidates for future data acquisition or 

development, particularly from among those addressing 

social and economic aspects.

• Consider a very limited number of additional variables to be included alongside the FAO GFRA data 

elements—enumeration of known invasive or T&E 

species, for example.

• Assist the island jurisdictions by providing standardized, peer-reviewed information to incorporate into 

their statewide assessments, and by using FAO GFRA 

tables as a primary database and (perhaps) Montréal 

Process criteria to establish a standard outline. Include 

basic demographic and socioeconomic data, and explicitly list local priorities and hot-button issues. 

• Build regional sustainability reports (Pacific, Caribbean, or combined) from consolidated data in the FAO 

GFRA. Provide comparison and analysis of local priorities and issues identified in the statewide assessments. 

Whatever the actual steps, consolidating these reporting 

processes makes good sense. Such a consolidation could 

substantially enhance the utility of the information 

presented for each island entity while substantially 

reducing the associated cost. It will also greatly facilitate 

cross-boundary sustainability assessments such as this 

report. 
I–16 Assessing Forest Sustainability in the Tropical Forests of the United States

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Assessing Forest Sustainability in the Tropical Forests of the United States I–19

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Pohnpei, Federated States of Micronesia.

Joseph Donnegan
Assessing Forest Sustainability in the Tropical Forests of the United States I–21

Chapter 3

Assessing Forest Sustainability in the Tropical Forests of the United States

Tropical Sustainability Key Findings and Recommendations

Kathleen A. McGinley, Guy C. Robertson, 

Kathleen S. Friday, and Constance A. Carpenter

Introduction

Comprehensive forest sustainability assessments are 

designed to evaluate the most important conditions and 

characteristics of forests as they relate to the ecological, 

social, and economic dimensions of sustainability. This 

type of assessment entails the consideration of a great deal 

of information. The Montréal Process Criteria and Indicators (MP C&I) framework provides an internationally 

agreed framework that greatly facilitates the organization 

and analysis of such information. However, the MP C&I 

do not by themselves provide an assessment of forest 

sustainability. Various methods have been suggested for 

developing rigorous and often quantified sustainability 

assessments (see Singh et al. 2009 for a useful survey of 

this work). The Montréal Process and its related reporting 

effort in the United States (USDA FS 2011), on the other 

hand, stress the importance of broad public discussions 

based on the best available scientific information in the 

assessment of forest sustainability. The resulting reports, 

including this one on U.S. and U.S.-affiliated tropical 

islands, are designed to inform dialogue and decisions as 

opposed to providing clear-cut determinations of sustainability. 

Summarizing of key findings plays an important part in 

this process. This report provides several summary levels: 

(1) each chapter devoted to specific Montréal Process 

criteria includes a criterion summary near the beginning; 

(2) key findings are gleaned from the criterion reports 

as a whole and are listed in the current chapter along 

with policy recommendations; and (3) these findings are 

further outlined in a brief executive summary included at 

the beginning of this report. Readers should be aware that 

the key findings included here are solely the choice of the 

authors based on their experience in producing the C&I 

chapters and their consideration of the various comments 

received in the process of producing and reviewing this 

report. Readers are further encouraged to consider the 

information presented here and elsewhere to reach their 

own conclusions about forest sustainability in the U.S. 

tropical islands. 

Are Forests in the U.S. Tropical 

Islands Sustainable?

Producing a simple yes or no answer to this question is 

a practical impossibility given the complexity of forest 

ecosystems and the subjective nature of sustainability 

definitions. However, we can highlight the following 

major points, which have direct bearing on the overall 

question of sustainability (additional key findings are 

presented in the following section):

• Forest area throughout the islands is relatively 

stable (and has in fact increased substantially in 

the Caribbean over the past 75 years). This fact 

indicates sustainability from the very limited standpoint of maintaining forest extent.

•	 Native biodiversity in the Pacific Islands continues to be threatened by various factors, notably the 

ongoing introduction of nonnative and invasive species, 

resulting in the endangerment and extinction of endemic species—a strong negative indication for forest 

sustainability.

• Novel assemblages of nonnative and native 

tree species are maturing over large areas of the 

Caribbean, indicating the dynamic nature of forest 

ecosystems. These forests may support ecosystem 

functions and biodiversity at levels comparable to 

native forests. However, their overall implications 

for sustainability are not yet fully understood and 

depend on both sustainability definitions and the 

future trajectory of these novel ecosystems.

Forest Area

Time-series data adequate to precisely measure changes 

in forest area are unavailable for most of the tropical 

jurisdictions considered in this report. However, available 

monitoring data, combined with piecemeal observations, 

suggest that forest land is relatively stable in many 

jurisdictions, with minor losses occurring in some 

areas—primarily as a result of human development pressure—and gains in other areas. There is no evidence of 

recent broad-scale loss of forest cover from either resource 

extraction or extensive conversion to agriculture. In fact, 

many islands have experienced forest recovery following 

the abandonment of agricultural lands that were converted 

from forests in the early 1900s. This recovery is especially 

pronounced in the Caribbean, where both Puerto Rico and 
I–22 Assessing Forest Sustainability in the Tropical Forests of the United States

the U.S. Virgin Islands (USVI) were once largely deforested and now exhibit more than 50-percent forest cover. 

As a result, from the critical standpoint of forest area, 

the tropical forests considered here demonstrate a fundamental measure of sustainability, though both the lack of 

adequate time-series data and anecdotal evidence of loss 

to development are cause for concern, especially where 

these issues continue unabated. The relative stability of 

forest area in the U.S. tropics mirrors developments in the 

temperate forests of the continental United States, where 

total forest area has been stable to slightly increasing 

for much of the past century (USDA FS 2011). Similar 

trends are documented in recent decades for the Northern 

Hemisphere at large (United Nations 2015). The maintenance of total forest area alone, however, is by no means 

sufficient to ensure overall forest sustainability. National 

or regional statistics may mask important changes at local 

levels or for specific forest types. Likewise, forest health, 

integrity (i.e., a lack of fragmentation), inherent biodiversity, and the provision of ecosystem services are crucial 

measures for tropical and temperate forests. Although the 

data describing these elements for U.S. tropical forests are 

less conclusive than those describing overall forest area, 

several areas for concern are indicated. 

Invasive Species in the Pacific

In the Pacific, where many of the islands have high 

numbers of endemic species and are subject to the 

ongoing influence of invasive species, forest health and 

the conservation of native biodiversity are threatened. 

Invasive species (plants, vertebrates, invertebrates, or diseases) may precipitate the loss of endemic species through 

predation and competition, or they can radically alter the 

structure and function of island forests, thus changing fire 

regimes and the provision of ecosystem services and products. The contribution of invasive species to the loss of 

biodiversity through the extinction of endemic species is 

a well-documented phenomenon in Hawaii (see Criterion 

1 in Part II), and it is occurring to a lesser degree in other 

areas. Although many of these changes are not necessarily 

a threat to the sustainability of forests when measured 

in terms of area, they may threaten the sustainability of 

essential forest components and characteristics—and 

they can present unique challenges to forest managers. 

Ecosystem services, including the provision of fresh 

water, may also be threatened.

Novel Forests in the Caribbean

In the Caribbean, the proximity of islands to each other, 

and to the mainland, allowed for greater mixing of species 

throughout the region’s ecological history, resulting in 

comparatively fewer endemic species and lower susceptibility to invasive species than in the Pacific. Also, 

the marked recovery of forests over the past century has 

resulted in novel assemblages of native and introduced 

tree species, most of which are in relatively young age 

classes. As these “novel forests” age, a crucial question 

is how the evolving forest structures and species mixes 

will influence forest conditions and thereby the values and 

services associated with forest sustainability. Evidence 

suggests that these forests have become increasingly naturalized, with introduced species persisting alongside their 

native counterparts, oftentimes contributing to biodiversity and the provision of ecosystem services (Lugo 2013). 

Similar processes are no doubt occurring in the Pacific 

(and elsewhere), but the extensive deforestation and recovery in Puerto Rico and the U.S. Virgin Islands means that 

they are especially pronounced in these islands.

Key Findings

•	 Island ecology and geography affect all aspects of

forest sustainability for the places considered in this 

report. Small land masses separated by large expanses 

of open ocean result in widely differing ecological, 

social, and economic conditions across the island 

jurisdictions considered in this report. Although these 

influences affect all of the islands, they are generally 

more pronounced on Pacific islands owing to their 

greater isolation.

• Approximately 3 million ac of tropical forests exist 

in the U.S. and U.S.-affiliated islands, ranging from 

nearly 1.5 million ac in the Hawaiian Islands to less 

than 24,000 ac in the Marshall Islands. Much of this 

forest land, particularly in Hawaii and the Caribbean, 

is composed of relatively young stands established on 

agricultural lands abandoned in the past century. The 

percentage of land in forest ranges from 90 percent in 

American Samoa to 36 percent in Hawaii (presettlement 

percentages can be assumed to approach 100 percent 

except in Hawaii, where high elevations and volcanic 

landscapes preclude forest cover) (see fig. 3.1 and 

Criterion 1 in Part II).

• Total acreage of forest land appears to be relatively 

stable, but this fact masks local and regional shifts in 

forest area and type. Losses of forest land to development are generally much less than losses of forests to 

agricultural development in the past century and before. 

In some islands, notably Puerto Rico, forest colonization of abandoned lands compensates for loss to 

development. In the Caribbean, forest area is significantly higher than it was 75 years ago, but development 

pressure may lead to locally significant fragmentation 

and loss of forest lands (Criterion 1 in Part II). 
Assessing Forest Sustainability in the Tropical Forests of the United States I–23

• The history of human settlement and subsequent 

patterns of land use strongly influence current forest

composition and structure throughout the islands.

Forest cover was virtually eliminated in Puerto Rico 

and the USVI to provide land for plantation agriculture 

in the colonial period. Current forests in that region 

exist largely as the result of natural regeneration and 

afforestation on once denuded lands, and current forest 

structure reflects this in its preponderance of trees in 

smaller size and younger age classes. Forests are seen 

as contributing to land rehabilitation in these instances. 

The same is true for some but not all areas of Hawaii. 

U.S.-affiliated Pacific islands have experienced long 

histories of human occupation with the integration 

of forest and agriculture in agroforestry systems in 

suitable areas. The overall result is that many of the 

forests found throughout the islands are composed of 

novel structures and species configurations. This results 

in both increasing wood volumes on forested lands as 

younger stands grow, and relatively high degrees of 

dynamism as stands age and tree species compete (see 

Criteria 1 and 2 in Part II). 

• The number of extinctions and endangered species listings are the biggest warning flag regarding

forest sustainability in the entire report. Pacific 

islands possess a high number and rate of occurrence 

of endemic species, which are often characterized by 

limited population numbers and geographic ranges, 

and which are thus subject to species extinctions and 

extirpations in the presence of increasing anthropogenic 

pressures. Some 760 plant and animal species across 

all the islands considered in this report are identified as 

at risk of extinction by the International Union for the 

Conservation of Nature (IUCN), and nearly 500 plant 

and animal species have been listed as endangered or 

threatened with extinction in the Northern Marianas, 

Guam, Hawaii, Puerto Rico, and the U.S. Virgin Islands 

by the U.S. Fish and Wildlife Service (freely associated 

states are not included in these listings). Hawaii stands 

out as particularly important owing to its number of 

endemics and endangered species. When viewed on a 

per-acre basis, these rates of endangerment are orders of 

magnitude higher than those encountered in the continental United States. Invasive species are often a major 

factor leading to extinctions; Hawaii, as an extreme 

example, faces the challenge of prioritization and triage 

involving hundreds of invasive species and hundreds of 

endangered species (see Criteria 1 and 3 in Part II).

• Climate change threatens entire islands and ecosystems. This report is focused on the assessment of 

current conditions, and the projected future impacts of 

climate change are generally beyond its scope. However, forests on the tropical islands are particularly 

susceptible to anticipated changes in sea levels, precipitation and temperature patterns, and tropical storm 

activity, and they already are feeling the effects of a 

changing climate, particularly in terms of increasing 

variability and extremes in weather patterns. In many of 

the smaller islands in the Pacific, where elevations are 

often low, the ratio of coastal to interior areas high, and 

opportunities for local migration of forest species and 

people constrained, the threats posed by global climate 

change are severe. They include the potential destruction of coastal mangrove forests and the intrusion of 

salt water into ground water. 

American Samoa

Micronesia (FSM)

Palau

Marshall Islands

Northern Marianas

U.S. Virgin Islands

Puerto Rico

Guam

Hawaii

Forest cover (percent)

1,490,875 ac 36%

63,833 ac 48%

1,213,205 ac

45,163 ac 55%

55%

75,407 ac 67%

36%

48%

55%

55%

23,257 ac 71%

90,685 ac 82%

143,466 ac 88%

43,631 ac 90%

0 10 20 30 40 50 60 70 80 90 100

Figure 3-1. Forest area and percentage of forest cover by island jurisdiction. FSM = Federated States 

of Micronesia. Source: for Hawaii, Gon et al. (2006); for all others, U.S. Forest Service Forest Inventory 

and Analysis.
I–24 Assessing Forest Sustainability in the Tropical Forests of the United States

• Commercial forestry is relatively limited, but linkages between people and forests are very strong.

Owing to the importance of traditional lifestyles for 

many island inhabitants, local residents rely on their 

forest resources in ways that are perhaps underappreciated by urban residents living elsewhere. Throughout 

the islands, forests provide subsistence foods, medicinal 

compounds, wood for local crafts and for construction, 

and other materials for cultural purposes and daily 

use. This reliance is increased by the fact that, with the 

exception of Hawaii, per-capita incomes are less than 

half the U.S. average, and subsistence activities are 

concomitantly more important. Moreover, island geography reinforces the linkage between forest conditions 

and other critical resources and services (e.g., drinking 

water, or sedimentation in coastal waters), and agroforestry, both for subsistence and commercial use, is a 

common practice on many islands (see Criteria 2 and 6 

in Part II).

• Forests are essential to the supply, quantity, and 

quality of island water resources, but are affected

by human uses to varying degrees. The conversion 

of forest lands to other uses has significantly affected 

water availability and quality on most of the inhabited 

islands. In many cases, nonforest land uses, such as 

agriculture and livestock grazing, as well as industrial, 

urban, and tourism development, have led to overuse 

of existing water supplies, sedimentation of waterways 

and bodies, including reservoirs, and contamination 

of surface and ground waters. Forest-based provision 

of water resources and services is affected by various 

disturbances, including feral ungulates, fire, nonnative 

invasive plant species, unsustainable water withdrawals 

and diversions, and climate change, indicating the need 

to consider water and forests together in the pursuit 

of sustainable forest management (see Criterion 4 in 

Part II). 

•	 Institutional capacity for forest management is

relatively limited, but islands partially compensate 

for this through regional collaboration and 

leveraging available federal programs. With the 

partial exception of Hawaii and Puerto Rico, the 

island jurisdictions covered by this report lack the 

resources and economies of scale to support the 

sorts of institutions that underlie forest management 

in the continental United States. In response, many 

of the islands engage in regional collaboration and 

exchange (in higher education, for example), and have 

instituted cross-boundary partnerships incorporating 

nongovernmental organizations, citizens groups, 

local and federal governments, and private sector 

representatives. Additionally, they have actively 

sought assistance from federal agencies to enhance 

their forest monitoring and management capacity. 

Continued support from federal programs and regional 

collaborations are an essential enabling condition for 

forest management (see Criterion 7 in Part II). 

• Forest regulations, standards, and guidelines are 

generally in place throughout the islands, but enforcement is uneven. This is likely the result of low 

institutional capacity and limited commercial use of 

forests. At the same time, islands also possess differing 

customs and land tenure arrangements that affect forest 

practices in nonregulatory ways (see Criteria 4 and 7 in 

Part II).

•	 Land tenure in the U.S.-affiliated Pacific jurisdictions often combines traditional resource allocation arrangements with Western concepts of land 

ownership and control. This includes communal 

decisionmaking processes and restrictions on the sale of 

lands to external entities. The combination of traditional 

and Western land-tenure arrangements has not always 

been smooth, and this fact points to the importance of 

cultural sensitivity when pursuing forest management in 

the islands (see Criterion 7 in Part II).

• Data that are both consistent over time and comparable across island jurisdictions are relatively rare.

The National Report on Sustainable Forests (USDA 

FS 2011) relied on well-established data series from 

the Forest Service’s Forest Inventory and Analysis 

unit (FIA), the U.S. Census and similar long-standing 

reporting activities, to assess forest sustainability for the 

continental United States. FIA has periodically measured forests in Puerto Rico since the mid-1980s and 

in the USVI since the mid-1990s, moving to cyclical 

measurements in 2014. FIA activities also have more 

recently expanded to include the tropical islands in the 

Pacific, and results will soon be available for the second 

measurement of the most recent islands to be included. 

U.S. Census and related socioeconomic information 

are not always directly comparable across different 

jurisdictions, especially for the freely associated states 

(Republic of the Marshall Islands, Federated States of 

Micronesia, and Republic of Palau), and various other 

data sets used in the national report are not available 

(see chapter 2 in Part I).

Policy Recommendations

To ensure forest sustainability in coming decades, The 

National Report on Sustainable Forests—2010 emphasizes the need for flexible and adaptive forest management actions informed by sound data and open public 

discussion. This general recommendation is equally 

relevant for forest management on U.S. and U.S.-affiliated 

tropical islands, and it is encouraging to see that efforts 

to strengthen data acquisition and public dialogue are 
Assessing Forest Sustainability in the Tropical Forests of the United States I–25

well underway in the islands. Given the heterogeneity of 

ecological, social, and economic conditions across the 

islands, it is hard to discern more specific policy recommendations that can be applied to all. We can nonetheless 

propose the following general observations to help guide 

management and policy formation in the future.

• Pursue consolidation in data development and 

reporting. Comparability across time and space is 

hampered by a lack of repeated sampling. Ongoing improvements in forest inventory data, in particular, will 

help ameliorate the lack of consistent information on 

forests, particularly in the Pacific. The islands produce 

a number of similar information reports on forests (e.g., 

the state-level Forest Action Plans, and submissions to 

the UN Food and Agriculture Organization’s Global 

Forest Resource Assessment) as well as reports specific 

to individual jurisdictions and issues. Consolidation and 

standardization of these reporting activities will benefit 

both information consumers (by providing greater comparability and transparency) and producers (through 

reporting efficiencies and avoiding duplicate efforts). 

Specific recommendations related to data development 

and reporting are included at the end of chapter 2.

• Foster public participation and sensitivity to 

cultural differences as an essential component of

forest planning and management activities. Most 

residents have a direct and material interest in forest 

conditions, outputs, and ecosystem services. Although 

many stakeholders may not exhibit the same degree 

of organization as those encountered on the mainland 

owing to lack of resources and economies of scale, they 

nonetheless have a substantial interest in management 

decisions and outcomes. Cultural relationships to the 

land will also differ, as will modes of engagement 

in decision processes. It is important that these 

stakeholders and their perspectives be adequately 

integrated in planning processes and management 

activities. This point highlights the need for investments 

in culturally aware capacity building to fully engage 

local stakeholders in adaptive forest management and 

planning processes.

• Focus management and data acquisition activities on 

forest conditions and outputs that are most valued 

by island residents. Island inhabitants rely on forests 

for a broad range of services and outputs, few of which 

enter into formal markets or are subject to quantified 

measurement. To the extent possible, forest reporting 

and planning exercises need to explicitly identify these 

outputs and their relative importance, then use this information to tailor biological inventories, socioeconomic data collection, and management actions accordingly. 

• Support ongoing collaboration between island entities through durable federal and regional programs. 

Extension of FIA inventory sampling to all the islands 

provides not just data but also a chance for islands to 

share information and experiences. Regional efforts like 

the Micronesia Challenge (see Criterion 7 in Part II) 

strengthen communication and collaborative management strategies between forest professionals and 

citizens. The value of these programs, and others like 

them, for small islands lacking capacity and economies 

of scale should not be underestimated, and they should 

be maintained.

These policy recommendations call for more data collection and more consultative processes that cannot be 

undertaken without the active participation of island forest 

managers who already are handling a range of responsibilities typical of larger institutions on the U.S. mainland. 

As a result, following these recommendations will 

require additional assistance in the form of research and 

technology transfer and the simple provision of additional 

outside funding. Assistance providers need to be aware of 

the specific ecological, cultural, and political conditions 

specific to each island, and to work in close collaboration 

with local experts and leaders. 

References

Gon, S.M.; Allison, A.; Cannarella, R.; Jacobi, J.D.; 

Kaneshiro, K.Y.; Kido, M.H.; Lane-Kamahele, M.; 

Miller, S.E. 2006. A gap analysis of Hawaii. [CDROM]. Moscow, ID: U.S. Department of the Interior, 

Geological Survey, National Gap Analysis Program.

Lugo, A. 2013. Novel tropical forests: nature’s response to 

global change. Tropical Conservation Science—Special 

Issue. 6(3): 325–337.

Singh, R.K.; Murty, H.R.; Gupta, S.K.; Dikshit, 

A.K. 2009. An overview of sustainability assessment 

methodologies. Ecological Indicators. 9: 189–212.

United Nations. 2015. Forests in the ECE region: trends 

and challenges in achieving the global objectives on 

forests. Geneva: Economic Commission for Europe and 

the Food and Agriculture Organization of the United 

Nations. 212 p. http://www.unece.org/forests/forests-inthe-ece-region-2015.html. (September 2016). 

U.S. Department of Agriculture, Forest Service 

[USDA FS]. 2011. National report on sustainable 

forests—2010. FS-979. Washington, DC: U.S. 

Department of Agriculture, Forest Service. 212 p. 

http://www.fs.fed.us/research/sustain/. (September 

2016).
I–26 Assessing Forest Sustainability in the Tropical Forests of the United States

El Yunque National Forest, Puerto Rico.

Gary Potts
Assessing Forest Sustainability in the Tropical Forests of the United States II–27

Part II.

Assessing Forest Sustainability in the Tropical Forests of the United States

Criterion and Indicator Reports
An ‘i’iwi (scarlet honeycreeper, Vestiaria coccinea) perches in an ‘ōhi’a (Metrosideros polymorpha) blossom in Hawaii. The ‘i’iwi is 

proposed for “threatened” status and ‘ōhi’a is being attacked by a new fungal disease, Ceratocystis fimbriata.

© Jack Jeffrey Photography. Used by permission.
Assessing Forest Sustainability in the Tropical Forests of the United States II–1

Kathleen A. McGinley and Constance A. Carpenter

Introduction

Tropical forests are among the most diverse ecosystems 

on Earth, hosting about two-thirds of the planet’s terrestrial biodiversity and providing benefits from local to 

global levels through the provision of goods and services 

(see, for example, Gardner et al. 2009). Biological diversity encompasses the range of physical environments and 

biotic communities (i.e., ecosystem diversity); groups of 

interbreeding natural populations (i.e., species diversity); 

and variation in the genetic makeup of plants, animals, 

and microorganisms (i.e., genetic diversity) over a 

specified area. Biological diversity is an important factor 

in ecosystem, species, and genetic response to natural and 

human disturbances and to the maintenance and recovery 

of essential ecological processes. 

Forest composition, structure, and inherent biodiversity 

change through succession and in response to disturbances. Tropical islands with high rates of natural or 

anthropogenic disturbances typically host forests in an 

ongoing state of recovery (see, for example, Chazdon 

2003, Foster et al. 1997, Waide and Lugo 1992). Recurring 

effects from tropical storms and hurricanes, cyclones, 

typhoons, and other natural disturbances produce patches 

of forest regeneration, maturity, and senescence as disturbance and recovery overlap in time and space (Chazdon 

2003). Forest succession that follows anthropogenic 

disturbances also may result in novel combinations of 

species, as natural processes lead to the remixing or reassembling of native and nonnative plant and animal species 

into novel communities that are adapted to anthropogenic 

environmental conditions (Lugo 2009). Nevertheless, the 

naturalization of nonnative species in island ecosystems 

affects successional dynamics in ways that are neither 

completely understood nor identical for all islands.

Under Criterion 1, we examine inherent biological diversity of tropical island forests, along with related forest 

conditions and conservation efforts. Systems of reserved 

lands are promoted to ensure that representative examples of all ecosystem types are preserved in perpetuity. 

Protection of a representative array of natural habitats and 

intact ecosystems is intended to safeguard examples of 

most species and their genetic diversity. Species that fall 

through this coarse filter can be targeted by finer filters, 

Criterion 1

Assessing Forest Sustainability in the Tropical Forests of the United States

Conservation of Biological Diversity

such as protecting lands necessary to the conservation of 

a particular species and species-specific in situ and ex situ 

conservation measures. 

Criterion Summary

Tropical and subtropical forests cover more than 3 million 

ac of the U.S. and U.S.-affiliated tropical islands, ranging 

from nearly 1.5 million ac in Hawaii to fewer than 25,000 

ac in the Republic of the Marshall Islands. Most of these 

island jurisdictions experienced significant conversion 

of forests to nonforest land uses in the past, but nearly 

all are predominantly forested today (except for Hawaii 

and Guam, which have 36 and 48 percent forest cover, 

respectively). Although much of the islands’ forest lands 

historically were converted to agricultural and urban uses, 

or to grasslands and badlands, forest area is stable on most 

islands, except a few areas that continue to lose forests to 

agriculture or to urban and suburban development (e.g., 

the U.S. Virgin Islands [USVI]). Reflecting these land use 

histories and natural island processes, most forests are in 

early to middle stages of succession, dominated by the 

smaller diameter trees indicative of younger aged forests. 

Significant areas of native forest have been replaced or 

altered by human activity, resulting in managed or novel 

forest ecosystems throughout much of the Pacific and 

Caribbean. 

Given that the islands were predominantly, if not entirely, 

forested prior to major human occupation, the change 

from forest to other land uses in effect represents a breaking up of once continuous forests. Islands with more land 

in nonforest land uses may have more fragmented landscapes, though some islands have maintained contiguous 

forest in certain regions or habitats (e.g., upland forests in 

Hawaii), while primarily converting forests to nonforest 

uses in others (e.g., lowland and coastal terrain in Hawaii). 

Other than Hawaii, which has the highest percentage of 

land in nonforest uses (64 percent), islands in the Pacific 

tend to have the least percentage of nonforest land use 

(<35 percent). Nonetheless, it is difficult to determine the 

degree of forest fragmentation for most of the islands.

The majority of forested land across the islands is privately owned, except in Hawaii, Guam, and Palau, where 

more than half of forest area falls under public ownership. 

Throughout the islands, there is a wide range in the area 

and percentage of forests that are formally or legally 
II–2 Assessing Forest Sustainability in the Tropical Forests of the United States

protected. In addition to formal forest protection, traditional governance structures have resulted in widespread 

community forest management and protection, particularly in the Pacific region. In many cases, traditional and 

community forest management have sustained a largely 

forested landscape that typically encompasses a combination of native forest, secondary forest, and traditional 

agroforest, as well as spiritually significant forest areas 

that are strictly protected. 

Although the islands are rich in plant and animal species 

per unit area, they do not host the levels of diversity found 

in mainland tropical areas, owing in part to their size and 

relative isolation. Nevertheless, many of the islands have 

high levels of endemism (i.e., species native to a specific 

island, group of islands, or other geographic area), which 

correlates with their isolation, climate, and heterogeneity 

of habitats. For example, Hawaii has exceptionally high 

levels of endemic species, including more than 99 percent 

of its identified terrestrial insects, spiders, and land snails; 

90 percent of its plants; and more than 80 percent of its 

breeding birds. 

Some 760 terrestrial plant and animal species across the 

islands are considered by the International Union for the 

Conservation of Nature (IUCN) to be at risk of extinction, 

and nearly 500 forest-associated plant and animal species 

have been listed by the U.S. Fish and Wildlife Service as 

endangered or threatened with extinction in the Northern 

Marianas, Guam, Hawaii, Puerto Rico, and USVI. Many 

of these at-risk plants and animals are endemic species, 

such that their extirpation would mean extinction of the 

global population and a permanent loss to world species 

richness. Extinction rates for island species are generally 

much higher than continental rates, in part because 

island species tend to have small populations, restricted 

genetic diversity, and narrow geographic ranges, making them more susceptible to the effects of natural and 

anthropogenic disturbances. A wide array of onsite and 

offsite efforts to protect at-risk forest species and native 

biodiversity in general has been established throughout 

the islands. These efforts have resulted in some notable 

successes, but the threat of species extinctions continues. 

Montréal Process Criterion 

Indicators

Criterion 1 of the MP C&I focuses on the biological 

diversity of forest systems and contains nine indicators 

related to ecosystems, species, and genetic diversity 

(listed below). There are fairly good data related to forest 

ecosystem diversity for many of the jurisdictions in this 

report, and some good data on forest species diversity 

for a few jurisdictions, but very limited data for genetic 

diversity for any of the jurisdictions. Given the limited 

amount of data related to forest genetic diversity and its 

conservation, the associated indicators were combined in 

this report. The nine MP C&I indicators for Criterion 1 

are as follows: 

• 1.01: Area and percentage of forest by forest ecosystem 

type, successional stage, age class, and forest ownership 

or tenure.

• 1.02: Area and percentage of forest in protected areas 

by forest ecosystem type, and by age class or successional stage.

• 1.03: Fragmentation of forests.

• 1.04: Number of native forest-associated species.

• 1.05: Number and status of native forest-associated 

species at risk, as determined by legislation or scientific 

assessment.

• 1.06: Status of onsite and offsite efforts focused on 

conservation of species diversity

• 1.07: Number and geographic distribution of forestassociated species at risk of losing genetic variation 

and locally adapted genotypes.

• 1.08: Population levels of selected representative 

forest-associated species to describe genetic diversity.

• 1.09: Status of onsite and offsite efforts focused on 

conservation of genetic diversity.

Indicator 1.01

Forest Area and Percent By Forest 

Ecosystem Type, Successional Stage, 

and Forest Ownership or Tenure

Total Forest Area

The vast majority of the U.S. and U.S.-affiliated tropical 

islands included in this report were originally completely 

or nearly completely forested and, with the exception of 

Hawaii and Guam, are predominantly forested today (fig. 

C1-1). Overall, the islands show a large variation in both 

total forest area and percentage cover, with no discernable 

correlation between these two measures. Although Hawaii 

has the least percentage of forest cover, it has the greatest 

total area of forest at nearly 1.5 million ac. At the other 

end of the spectrum, American Samoa has the highest 

percentage of forest cover but a comparatively small 

total forest area. At 23,252 ac, forest area in the Marshall 

Islands is approximately 1/50th that of Hawaii. 

Historically, most islands underwent some (and often a 

significant degree of) conversion of forest to agricultural 
Assessing Forest Sustainability in the Tropical Forests of the United States II–3

and grazing lands, or to grasslands and badlands, 

typically tied to periods of initial settlement and the 

introduction of fire, or resulting from colonization and 

population growth. Military occupation and associated 

deforestation and other ecosystem disturbances (including 

atmospheric nuclear testing) before, during, and after 

World War II occurred on several islands in the Pacific. 

Conversely, relatively few isolated islands (e.g., some atoll 

islets and rock islands of Palau) and those with forests on 

steep, rugged terrain or very wet climates (e.g., Tutuila in 

American Samoa and central mountains of high islands 

in eastern Micronesia) experienced very little historical 

forest loss and conversion, particularly when compared to 

other more accessible islands and those with more gently 

sloped terrain (e.g., Hawaii, Puerto Rico). 

Over time, many deforested and converted lands were 

abandoned and reestablished as forests through natural 

regeneration, active planting, or both. These “forest 

transitions” typically are associated with shifts in socioeconomic dynamics, including changes that result from 

globalization, industrialization, and urbanization, as well 

as from the direct effects of environmental legislation 

and conservation efforts (Aide and Grau 2004, Meyfroidt 

and Lambin 2011, Rudel et al. 2000). Today, most islands 

maintain at least some agricultural areas where forests 

once grew, and most continue to convert some forest area 

to development for residential, business, military, industrial, and tourism purposes. In the Caribbean, forests have 

recuperated significantly since the height of agricultural 

production in the early 20th century, yet some forest 

conversion persists, particularly for urban and tourism 

development (e.g., St. Croix) (Brandeis and Turner 2013a, 

2013b). In Puerto Rico, in particular, more than 90 percent 

of the nearly continuous original forests had been cleared 

for agriculture by the early 1900s. However, through the 

reversion and replanting of abandoned agricultural lands, 

forests have since rebounded to cover more than half of 

Puerto Rico. To date, forest recovery in Puerto Rico has 

outpaced any forest conversion to development or other 

uses, forestalling any new net loss of forests for now 

(Brandeis and Turner 2013a). 

Hawaii, once nearly completely covered by forests, is 

now about 36-percent forested owing in part to sustained 

agricultural production and development in areas once 

forested. In the Pacific, there is a broad range in forest 

distribution and dynamics. In Palau, for example, forests 

have been maturing and increasing on Babeldaob (at least 

until 2003), while forests were being lost to urban development and conversion to nonforest vegetation on Peleliu, 

Koror, and Angaur (Donnegan et al. 2007). In American 

Samoa, total forest area declined by at least 1.3 percent 

from 1988 to 2001. During the same period, mangrove 

forests were reduced by about 18 percent by development 

and urbanization (Donnegan et al. 2004a). In the Northern 

American Samoa

Micronesia (FSM)

Palau

Marshall Islands

Northern Marianas

U.S. Virgin Islands

Puerto Rico

Guam

Hawaii

Forest cover (percent)

1,490,875 ac 36%

63,833 ac 48%

1,213,205 ac

45,163 ac 55%

55%

75,407 ac 67%

36%

48%

55%

55%

23,257 ac 71%

90,685 ac 82%

143,466 ac 88%

43,631 ac 90%

0 10 20 30 40 50 60 70 80 90 100

Figure C1-1. Forest cover as a percentage of total land area for the U.S. and U.S.-affiliated tropical 

islands (2001–2009). Source: for Hawaii, Gon et al. (2006); for all others, U.S. Forest Service Forest 

Inventory and Analysis (FIA). Note: FIA classifies “forest” as areas having “at least 10 percent tree 

cover,” and may include agroforests and mangrove forests. For Hawaii, Gon et al. (2006) used the 

National Vegetation Classification System, classifying “native” forest as areas at least 25 percent 

vegetated, whereby native “open forest” is 25 to 60 percent vegetated and native “closed forest” is 

>60 percent vegetated. Nonnative “forest” vegetation types are at least 15 percent vegetated. 
II–4 Assessing Forest Sustainability in the Tropical Forests of the United States

Marianas, trends detected from photointerpretation and 

mapping suggest “conversions of forest and nonforest 

vegetation to urban land, especially on Saipan where 

urban land more than tripled” between 1989 and 2005 

(Donnegan et al. 2011a). 

Forests by Ecosystem Type 

(Holdridge Life Zone)

Vegetative community classes have not been fully 

developed for all of the islands, and those that do exist 

have not been standardized across the islands or similar 

life zones. Therefore, we examine island forests according 

to the Holdridge Life Zones system, which can be used as 

a proxy for ecosystem or community type. The Holdridge 

Life Zones system empirically defines the conditions for 

vegetation growth based on bioclimatic information (i.e., 

biotemperature, precipitation, and evapotranspiration 

(Holdridge 1967) (fig. C1-2). Its application facilitates 

global comparisons of ecological information, particularly 

across the tropics (Halasz 2007). 

Life zone maps developed by Ewel and Whitmore (1973) 

for the Caribbean and by Tosi et al. (2002) for the Pacific 

(except the Marshall Islands) indicate the potential for a 

given area to support characteristic vegetative communities. Much of the Pacific and the entire Caribbean region 

geographically fall within the tropics, delineated by the 

Tropic of Cancer to the north and Tropic of Capricorn 

to the south. However, when bioclimatic variables are considered within the Holdridge Life Zones system (e.g., relatively uniform and high biotemperatures), more than 90 

percent of the total land base of these islands is classified 

as subtropical. Based on their Holdridge classification, 

the vast majority of these islands are assumed to have 

been predominately to entirely forested prior to human 

settlement (Ewel and Whitmore 1973, Tosi et al. 2002). 

Hawaii is the most diverse jurisdiction with 27 life zones; 

at the other end of the spectrum, the USVI comprise two 

life zones. 

Brandeis and Turner (2013a, 2013b) and Bennett and Liu 

(n.d.) used geographic information system analysis, overlaying life zone maps with vegetation maps, to determine 

current acreages of land cover and use types per life zone 

(fig. C1-3; table C1-1). Today, the most abundant forested 

life zone across all the islands is subtropical moist forest, 

three-fourths of which occurs in Puerto Rico given its 

desert

dry

tundra

desert

desert

desert

desert

dry

scrub

moist

forest

wet

forest

rain

forest

rain

forest

wet

forest

wet

forest

wet

forest

moist

forest

moist

forest

dry

forest

dry

forest

thorn

woodland

moist

forest steppe desertscrub

rain

forest

rain

forest

superaridperhumidsub- humid

humid

semiaridperarid arid superhumid

moist

tundra

wet

tundra

rain

tundra

desert desert

62.5 

125

250

500

1000

2000

4000

8000

16000

0.125

0.25

0.5

1

2

16

32

4

8

latitudinal

regions

humidity provinces

polar

subpolar

boreal

cool temperate

warm temperate

subtropical

tropical

alvar

1.5 °C

3 °C

6 °C

12 °C

24 °C

alpine

subalpine

montane

lower montane

premontane

critical

temperature 

line

altitudinal

belts

biotemperature

very dry

forest

thorn

steppe /

woodland

desert

scrub

desert

scrub

potential evapotranspiration ratio

annual precipitation (mm)

Figure C1-2. Holdridge Life Zone classification system. Source: Holdridge (1967), cited by Halasz (2007).
Assessing Forest Sustainability in the Tropical Forests of the United States II–5

1,600,000

1,400,000

1,200,000

1,000,000

800,000

600,000

400,000

200,000

0

160,000

140,000

120,000

100,000

80,000

60,000

40,000

20,000

0

AcresAcres

Hawaii

Puerto Rico

Micronesia

Palau

Guam

Northern Marianas

American Samoa

Marshall Islands

U.S. Virgin Islands

Subtropical Nival / 

subalpine

Subtropical Montane / 

Lower Montane moist / 

wet / rain forest

Subtropical Montane / 

Lower Montane / dry 

forest

Subtropical wet / rain 

forest

Subtropical moist forest

Subtropical dry forest

Tropical / Premontane 

dry / moist / wet / rain 

forest

Figure C1-3. Forested acreage of Holdridge Forest Life Zones in the U.S. and U.S.-affiliated tropical islands (2001–2009). 

Source: Bennett and Liu (N.d.); Brandeis and Turner 2013a, 2013b. 

Table C1-1. Forest area per Holdridge forest life zone group in the U.S. and U.S.-affiliated tropical 

islands, 2003–2013

Total 

forest 

land area

Tropical/

premontane 

dry/ moist/

wet/rain 

forest

Subtropical 

dry forest

Subtropical 

moist 

forest

Subtropical 

wet/rain 

forest

Subtropical

 montane/

lower 

montane 

dry forest

Subtropical 

montane/

lower 

montane 

moist/wet/

rain forest

Subtropical 

nival/

subalpine

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Acres - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

Caribbean:

U.S. Virgin Islands 45,163 28,896 16,266

Puerto Rico 1,213,205 199,691 578,801 398,145 21,670

Pacific:

Hawaii 1,489,251 186,894 172,522 391,890 44,495 691,592 1,858

American Samoa 40,265 24,796 697 14,772

RMI 24,329 24,329

FSM 151,834 151,834

CNMI 49,885 32,964 16,921

Guam 64,555 31,882 20,055 12,618

Palau 85,702 85,702

 Total 3,218,897 351,507 380,915 864,581 835,275 44,495 720,587 1,858

RMI = Republic of the Marshall Islands; FSM = Federated States of Micronesia; CNMI = Commonwealth of the Northern Mariana 

Islands. Source: Bennett and Liu (N.d); Brandeis and Turner 2013a, 2013b.
II–6 Assessing Forest Sustainability in the Tropical Forests of the United States

relatively large area of forest. Subtropical wet forest is also 

abundant. Almost a quarter of the total forest area occurs 

in mountainous terrain (i.e., montane), most of which is 

found in Hawaii. The Pacific Islands are small, but collectively they contain seven tropical and four subtropical 

forested life zones ranging from dry forest to rain forest 

as well as some pre-montane forested life zones (note: 

some life zones have been combined in fig. C1-3 

and table C1-1). 

Native and Novel Forests

“Native forests” are naturally established ecosystems 

composed primarily of indigenous species, many of 

which have evolved together over thousands to millions 

of years (Friday et al. 2008, Kagawa et al. 2009, Parrotta 

et al. 1997). “Novel forests” are those that have emerged 

naturally, in response to new environmental conditions 

created by human activity that result in the remixing or 

reassembling of indigenous and introduced or nonnative 

species into novel or new communities (Lugo 2009). 

Novel forests typically exhibit ecosystem functions such 

as soil protection, nutrient cycling, and wildlife habitat 

similar to (and in some cases exceeding) those functions 

exhibited by native forests (Lugo 2009). Yet, while nonnative-dominated novel forests in Puerto Rico have been 

shown to “provide suitable regeneration sites for native 

species and promote native species abundance,” in Hawaii 

native trees and plants “are largely unable to colonize” 

novel forests once they are established, owing in part to 

the “wide diversity of growth strategies among the exotic 

species on Hawaii [which] may limit the opportunities 

for native plants to colonize exotic-dominated forests” 

(Mascaro et al. 2008). Overall, the islands in this report 

do maintain some forest communities composed mainly 

of native species, but increasingly they host forests that 

include a mix of native and nonnative species. Forest 

communities that recolonize abandoned agricultural 

lands are generally a mixture of native and nonnative 

species, of which the latter may have been purposefully 

or inadvertently brought to the islands. They are different 

from planted forests or plantations, and from agroforests, 

which intentionally integrate trees and shrubs with crop 

and animal farming systems. 

In the Caribbean, very little native forest remains on the 

inhabited islands of Puerto Rico and the USVI because 

these were nearly completely deforested for agricultural 

uses during the late 18th and early 19th centuries. In 

Puerto Rico, remnants of native forest can be found in 

the peaks of the highest mountains and along some steep 

slopes, as well as on the less populated and uninhabited 

smaller islands and cays off the coast of the main island. 

Native and nonnative tree species are found in the vast 

majority of the forested areas of Puerto Rico, regenerating 

naturally in established, maturing forests, as well as on 

recently abandoned agricultural land. For example, the 

African tuliptree (Spathodea campanulata), an introduced 

tree species, represents more basal area and frequency in 

number than any other tree species on the island (Brandeis 

and Turner 2013a, Brandeis et al. 2007a). Moreover, 

it also is important in the understory of most forests, 

indicating its capacity to regenerate (Brandeis and Turner 

2013a). Nonetheless, three native tree species, American 

muskwood (Guarea guidonia), gumbo limbo (Bursera 

simaruba), and pumpwood (Cecropia schreberiana), 

were the next three most commonly found tree species 

on the island, indicating that native trees are regenerating 

successfully across the island, despite significant effects 

from human activities throughout much of the landscape 

(Brandeis and Turner 2013a, Brandeis et al. 2007a). 

Although Hawaii has lost a significant amount of its original forest cover, 22 percent of the total area is classified as 

native forest (Gon et al. 2006). As inferred from life zone 

mapping, 77 percent of the state’s original, native forest 

cover has been lost. Yet, 61 percent of remaining forest 

land in Hawaii is considered to be native forest cover 

(Gon et al. 2006) (fig. C1-4). Polynesian settlement in the 

Hawaiian Islands in the 4th and 5th centuries CE altered 

coastal, dry, and some mid-elevation forest types through 

agriculture and the use of fire (Graves and Addeson 1995). 

After European contact in the late 1700s, the expansion of 

agriculture and the introduction of cattle, later followed 

by urban land uses, accelerated forest loss, particularly in 

lower elevations (Graves and Addeson 1995). Today, there 

is very little native vegetation below 2,000 ft elevation 

in Hawaii. Native forest types exhibiting significant 

reduction in range include the subalpine forest (2 percent 

forested), montane dry forests (11 percent forested) and 

the subtropical (lowland) dry forest communities (17 

percent forested) (Bennett and Liu, n.d.). In particular, 

the mesic montane forest type has been all but lost to 

the effects from timber logging (e.g., Acacia koa), sugar 

plantations, cattle ranching, and spread of invasive grasses 

that can lead to increased susceptibility to and severity of 

wildfire (Denslow et al. 2006, Gon and Olson 1999). 

Human settlements have influenced Hawaiian and other 

Pacific islands’ forest composition and structure for a 

thousand years or more. Throughout the region, plants 

used historically for medicine and food are found in 

now-remote areas, which were inhabited, harvested, 

and modified by earlier, denser human populations, 

prior to the introduction of Western diseases and the 

modern concentration of populations in developed 
Assessing Forest Sustainability in the Tropical Forests of the United States II–7

areas (Donnegan et al. 2011b). For example, paleoenvironmental evidence from Palau suggests that, some 

2,500 years ago, forests were modified and converted 

to agricultural uses that often incorporated terracing 

practices (Athens and Ward 2002). More recent human 

disturbances throughout the region, including agricultural 

practices and forest clearing associated with military and 

mining activities, have resulted in the expansion of novel 

forest ecosystems as the activities are abandoned and 

forests regenerate with new combinations of native and 

nonnative species. In particular, the Pacific Campaign of 

World War II had significant impacts on the vegetation 

of many of these islands. Throughout Micronesia, 

lowland forest vegetation has been “heavily modified 

over thousands of years of human activity, including 

agroforestry and tree gardening” (Raynor and Fownes 

1991). Today, most Micronesian and American Samoan 

forests are “a mixture of native and nonnative species, 

primarily of smaller tree size classes.” Some native 

forests are still found in the intertidal zone (mangroves), 

limestone regions (especially the uninhabited rock 

islands of Palau and military bases of Guam), along 

steep slopes and ravines, and on the central high slopes 

in Pohnpei, Kosrae, the American Samoan high islands, 

and Babeldaob (Palau). Native forests have largely been 

replaced by agroforestry systems—especially coconut 

plantations in the Marshalls and other atolls in the region, 

except for some of the undisturbed islets where native 

mixed-broadleaf forest remains largely undisturbed by 

humans (Donnegan et al. 2004a, 2004b; 2007; 2011a, 

2011b, 2011c). Additionally, in Guam, much of the forest 

is affected by the high number and density of nonnative 

Leucaena leucocephala shrubs, which spread extensively 

following widespread forest clearing during World War II 

(Donnegan et al. 2004b).

0 10 20 30 5

Hawai`i

County of Kaua`i

County of Maui

City & County of Honolulu

County of

Hawai`i

Ni`ihau Kaua`i

O`ahu

Moloka`i

Lana`i

Kaho`olawe

Maui

Honoluluk

k

k

k

k

k

Hilo

KailuaKona

Kaunakakai

Wailuku

Lihu`e

State of Hawai`i

Department of Land and Natural Resources

Division of Forestry and Wildlife

Date of Production: May 30, 2008

Contact: Ronald Cannarella

k

161°0'0"W 159°0'0"W 157°0'0"W 155°0'0"W

22°0'0"N

21°0'0"N

20°0'0"N

19°0'0"N

Main

Hawaiian Islands 3

Forest Stewardship Program

Spatial Analysis Project

Miles

10 = Native forest

 8 = Mixed native/

 alien forest

 5 = Alien-dominated 

 forest

Forested

Lands

Data source: Hawai’i GAP

Analysis Project statewide

landcover map (2005), 

Hawai’i State GIS and

National GAP Program. Data

were aggregated from 37

classes to three classes: 

native forest, mixed native/

alien, and alien forest.

Assumption: forest land is 

one of the 12 data layers 

required by SAP. For this

analysis, native forest 

received the highest value

of 10. Lands that are not 

currently forested are not 

included in this layer.

Honolulu

Figure C1-4. Forested lands in the main Hawaiian Islands (Conry et al. 2008). GIS = geographic information system; 

GAP = Gap Analysis Program; SAP = Spatial Analysis Project.
II–8 Assessing Forest Sustainability in the Tropical Forests of the United States

Forest Successional Stage and Age

Measures of forest successional stage or age are important for understanding variations in their structure and 

composition over time and across the landscape, but such 

measures are difficult to come by in general, and in the 

tropics in particular, partly because the number of tree 

rings in tropical trees does not correspond to age in years, 

but to variable time periods related to available moisture. 

Where available, forest age can be estimated by analyzing 

multitemporal satellite images, aerial photographs, or 

other measures, yet these are scarce for most tropical 

islands. Kennaway and Helmer (2007) mapped land use in 

Puerto Rico from 1951 through 2000, demonstrating that, 

by 2000, only 21 percent of the total forest area was more 

than 50 years old. Twenty-seven percent was aged 23 to 49 

years, 31 percent was aged 10 to 22 years, and 21 percent 

of the total forest area was less than 10 years old. 

Forest stands that are classified according to the predominant diameter class of live trees can be used as an approximate indicator of forest successional stage, specifically 

when combined with information related to land use 

history and forest life zone, type, species composition, 

and stocking. Forest size-class data are available from 

the Forest Service’s Forest Inventory and Analysis (FIA) 

program for most of the jurisdictions (except Hawaii). In 

general, these data reflect 

known forest types and land 

use histories of the islands, 

with the majority of forest 

stands dominated by trees 

less than 11 inches diameter at breast height (dbh), 

indicating mostly young- and 

intermediate-aged forests of 

early and mid-successional 

types (fig. C1-5).

Forests in the Marshall 

Islands represent the highest 

proportion of trees categorized as “large diameter” 

(60 percent: ≥ 11 inches dbh) 

(fig. C1-5). American Samoa 

and the Federated States of 

Micronesia (FSM) also have 

a significant portion of trees 

in the large stand class (≥ 11 inches dbh: 36 percent and 

31 percent, respectively). The dominance of comparatively 

large trees on these islands is mostly attributed to the 

presence of coconut trees in plantations and agroforests 

(Donnegan et al. 2004a, 2007, 2011b). While individual native and nonnative trees greater than 21 inches 

dbh are found throughout most forest stands across 

all jurisdictions, and those trees may in fact dominate 

the canopy, only the FSM exhibits any forest area (1.7 

percent) dominated in number by trees this large. At the 

other end of the spectrum, the USVI exhibit the highest 

proportion of forested area dominated by small-diameter 

trees (85 percent: 1 to 4.9 inches dbh), reflecting not only 

the relatively early stage of succession of most forests, but 

also the predominance of subtropical dry forest, which 

typically consists of slower growing, smaller sized trees 

(Brandeis et al. 2007b). In Guam and the Northern Marianas, forests tend to be dominated by smaller trees, owing 

to frequent disturbance by typhoons, and more recently, to 

human-induced land use effects and change (Donnegan et 

al. 2004b, 2011a). Finally, in Puerto Rico, most forests are 

considered to be relatively young and are dominated by 

smaller stand classes in which regeneration is abundant. 

These forests are growing, “with a slight tendency toward 

increasingly larger diameter stands” (Brandeis and Turner 

2013a).

Figure C1-5. Forest area dominated (>50 percent) by nonstocked, small-, medium-, and largediameter stand classes. Source: U.S. Forest Service Forest Inventory and Analysis (data for Hawaii 

were not available at the time this report was published); dbh = diameter at breast height.

100

90

80

70

60

50

40

30

20

10

0

Forest cover (percent)

Large diameter 

(11–19.9 inches dbh)

Medium diameter

(5–10.9 inches dbh)

Small diameter

(<5 inches dbh)

Nonstocked

Micronesia

Palau

U.S. Virgin Islands

Northern Marianas

Puerto Rico

Guam

Marshall Islands

American Samoa
Assessing Forest Sustainability in the Tropical Forests of the United States II–9

The distribution of forest stand-size classes throughout 

the islands reflects natural and anthropogenic processes, 

with significant expanses of native forests having been 

replaced or altered by active and abandoned agroforests in 

the Pacific (Donnegan et al. 2004a, 2004b; 2007; 2011a, 

2011b, 2011c) and by secondary forests in the Caribbean 

(Brandeis and Turner 2013a, 2013b). For example, coconut 

plantations and mixed coconut forests are widespread 

in American Samoa and the Marshalls (Donnegan et al. 

2004a, 2011c). In the FSM, forests are “generally dense 

with larger trees, reflected in high basal area and wood 

volume on a per-acre basis.” In addition, ancient and 

ongoing “tree gardening” has resulted in “an abundance 

of fruit and nut trees interspersed with other canopy trees” 

(Donnegan et al. 2011b). And, in Puerto Rico and the 

USVI, as in Palau, the conversion of forest to agriculture 

in the early to mid-20th century largely has given way to 

agricultural abandonment and the reversion of converted 

lands to grassland and eventually to secondary forest 

across a large part of the landscape (Brandeis and Turner 

2013a, 2013b, Donnegan et al. 2007). 

Forest Ownership

Forests are mostly privately or communally owned 

in all jurisdictions except Hawaii, Guam, and Palau, 

where more than half of the total forest area falls under 

public (i.e., governmental) ownership (53 percent, 56 

percent, and at least 70 percent, respectively) (table C1-2). 

Although the national governments of Micronesia and 

Palau do not own forest land, state and local governments 

within those nations do own a range of forest area, 

including 70 percent or more in Palau. Land ownership 

and tenure is complex in many of the islands, particularly 

in the Pacific, and is discussed in greater detail under 

Criterion 7. 

Table C1-2. Percentage of forest area by ownership type and jurisdiction, circa 2010

Total forest area

Private

Local jurisdiction

(national/state/municipal)

Federal

(United States)

Percent

U.S. Virgin Islands 83 0 17

Puerto Rico 85 11 4

Hawaii 47 44 9

American Samoa 96 (or more)

(includes 

“communal”)

4 (or less) 0

(13 percent is leased to the 

National Park Service)

Marshall Islands 100 0 0

(most of Kwajelein Atoll is 

leased to the U.S. military)

Micronesia:

 Chuuk and Yap 

 Pohnpei

 Kosrae

About 100

About 64

27

About 0

About 35

16

(an additional 58 percent 

is constitutionally 

designated for release 

to private ownership)

0

0

0

Northern Marianas N/A About 50 N/A

(parts of Tinian are leased 

to the U.S. military)

Guam 51 19 29

Palau 30 (or less) 70 (or more) 0

Sources: American Samoa Community College 2010; Biza 2012; Brandeis and Turner 2013a, 2013b; 

Commonwealth of the Northern Mariana Islands 2010; Donnegan et al. 2011a; Gon et al. 2006; Guam 

2010; Republic of the Marshall Islands 2010; Republic of Palau 2010.

N/A = not available.
II–10 Assessing Forest Sustainability in the Tropical Forests of the United States

Indicator 1.02

Forest in Protected Areas

Throughout the islands, there is a wide range in the area 

and percentage of forests that are formally protected 

through parks, reserves, protected areas, and other official 

measures. Formally protected forests are found on public, 

private, and communal lands. In addition to formally 

protected areas, most islands exhibit several other forms 

of forest protection through traditional practices, collaborative arrangements, and private measures. However, 

statistics on forest protection are not available or comparative for all jurisdictions. 

The USVI, Puerto Rico, and Hawaii have been assessed 

through the National Gap Analysis Program, which 

provides information on the status and conservation of 

plants and animals across the landscape, including the 

assessment of the status of land stewardship in terms of 

protected area location and conservation measures (table 

C1-3). Hawaii has the greatest total extent of formally 

protected forest (227,314 ac), followed by Puerto Rico 

(134,699 ac), while the USVI had the highest proportion 

of forest formally protected (14.7 percent) (Gap Status 1 

+ 2) (Gon et al. 2006, Gould et al. 2007, 2013). 

(26.9 percent protected) and wet (15.4 percent protected) 

forest types. Conversely, moist woody forest vegetation 

had less than 4 percent of its range protected (3.9 percent 

protected) (Gould et al. 2007).

In Hawaii, 13.1 percent of forests are protected (Gap 

Status 1 + 2) (Gon et al. 2006). Forest types with the 

greatest percentage of their range protected (Gap Status 1 

+ 2) are the koa forest (93 percent), olopua-lama forest (93 

percent), and closed ohia forest (32 percent). Conversely, 

closed hala and Pouteria forest cover types have none of 

their range formally protected. Using a broader definition 

of “protected forest area” to include forests where conversion to other land uses is prohibited, but where resource 

extraction and other potentially intense uses are permitted 

(e.g., Gap Status 3), indicates that Hawaii has nearly 43 

percent of its total forest area under some formal protection or management, followed by 16.8 percent in the USVI 

and 11.7 percent in Puerto Rico (Gap Status 1 + 2 + 3) 

(Gon et al. 2006; Gould et al. 2007, 2013) (table C1-4).

In 2006, Palau, Micronesia, the Marshalls, Guam, and the 

Northern Marianas established the Micronesia Challenge—a regional effort to achieve “effective conservation” of 20 percent of terrestrial areas and 30 percent of 

marine areas by 2020 (PCS and TNC 2011). As of 2011, 

between 9 and 23 percent of each jurisdiction, including 

forested areas, were considered to be within a “protected/

managed area” and contributing to the Challenge’s goals. 

Although these statistics are not entirely indicative of a 

Table C1-3. Area and percentage of forests in 

protected areas (Gap Status 1 + 2), 2003–2013

Jurisdiction Area Total forest

Acres Percent

U.S. Virgin Islands 8,575 14.7

Puerto Rico 134,699 11.6

Hawaii 227,314 13.1

Source: Gon et al. 2006; Gould et al. 2007, 2013.

Among the islands in the USVI, nearly three quarters of 

forests on St. John are formally protected; 65 percent of 

this area is within Virgin Islands National Park. However, 

less than 5 percent of the forests on St. Thomas and St. 

Croix are found in protected areas (Gould et al. 2013). In 

Puerto Rico, 11.6 percent of forests (at least 25-percent 

tree cover) are formally protected (Gap Status 1 + 2) 

(Gould et al. 2007). Forested areas with a priority on 

biodiversity conservation (Gap Status 1) include two management areas in the El Yunque National Forest: the Baño 

del Oro and El Toro Wilderness Areas. Flooded forests 

(i.e., mangrove and Pterocarpus swamp forests) in Puerto 

Rico had the greatest proportion of their total area under 

protection (46 percent: Gap Status 1 + 2), followed by dry 

Table C1-4. Forest area under protection or 

management and prohibition of conversion 

to other land uses, 2003–2013

Jurisdiction

Total forest area 

protected/managed

Percent

U.S. Virgin Islandsa 16.8

Puerto Ricoa 11.7

Hawaiia 42.8

American Samoab 20–22

Marshall Islandsb Data not available

(16 percent of all lands)

Micronesiab 15-17

Northern Marianasb 9–13

Guamb 23–48

Palaub 20–24

Source: Gon et al. 2006; Gould et al. 2007, 2013; PCS 

and TNC 2011.

a

 Gap Status: 1, 2, and 3.

b

 Micronesia Challenge: “protected/managed.” 
Assessing Forest Sustainability in the Tropical Forests of the United States II–11

strong measure of legal protection of these areas, they do 

offer a category of protection that is regionally consistent 

and encompasses international agreement to progress 

toward formal protection (PCS and TNC 2011).

Indicator 1.03

Fragmentation of Forests

The fragmentation of forested land can occur as a result of 

anthropogenic or natural processes. It can lead to species 

isolation and loss, habitat degradation, and a reduction in 

the capacity of the forest to sustain the natural processes 

necessary for maintaining ecosystem health. Throughout 

the islands, forest fragmentation largely results from 

human-induced conversion of forests to agriculture, and, 

more recently, to urban uses. Additional fragmentation 

results from the reversion of forest patches on historically 

pastured or farmed land. In Hawaii, in particular, natural 

fragmentation of forests has been occurring for some 

400,000 years or more from volcanic activity (Flaspohler 

et al. 2010). During these events, lava flows into once 

continuous forests, leaving behind forest fragments of 

varying sizes (Flaspohler et al. 2010). These forested 

areas or fragments, known as kipuka, have different soils, 

vegetation, and microclimates than the surrounding land 

matrix because they were spared when the lave flowed 

around them and are found in different stages of succession than their neighbors (Flaspohler et al. 2010).

Direct measures of forest fragmentation are hard to obtain 

for most of the islands. In Puerto Rico, while forest is the 

dominant land cover across the landscape (55 percent), 

forest fragmentation is extensive (Helmer 2004, Helmer 

and Ruefenacht 2005). Specifically, by about 2000, 96 

percent of all forest fragments in Puerto Rico were less 

than 10 ha (24.7 ac) in size, and nearly three fourths of 

all fragments were smaller than 1 ha (2.47 ac) (fig. C1-6). 

Conversely, only one forest fragment measured greater 

than 100 000 ha and only one other fragment was between 

10 000 and 100 000 ha in size (Helmer and Ruzycki 2008, 

Kennaway and Helmer 2007, Kennaway et al. 2008). 

Nevertheless, forested landscapes and the state of forest 

fragmentation are dynamic. For example, Lugo (2002) 

documented a decrease in the number and size of agriculture and pasture land cover fragments and an increase 

100,000

10,000

1,000

100

10

1

Number of fragments

Area of fragments (hectares)

6,634

1,121

153

14

228

57 57

20

12

2 2

0 0 11 01 0 0 01 0 0

2

3

>0.1–<1

>1–<10

>10–<100

>100–<1000

>1000–<10 000

>10 000–<100 000

>100 000

Puerto Rico

Vieques

Culebra

Mona

24,029

Figure C1-6. Frequency of forest patches in Puerto Rico in 2000. Produced by E.H. Helmer, 2010 from 

Helmer and Ruzycki, 2008; Kennaway and Helmer, 2007; Kennaway, et al. 2008.
II–12 Assessing Forest Sustainability in the Tropical Forests of the United States

in urban and forest fragments between 1977 and 1995 in 

northeastern Puerto Rico in a study of landscape-level 

land cover trends for six major land cover types—agriculture and pasture, closed forest, open forest, wetlands, 

open water, and urban. The results indicated a reduction 

in the fragmentation of the landscape during this period as 

forest and urban area increased, forming more and larger 

fragments, primarily regenerating or building over former 

fragments of agriculture and pasture. 

In Hawaii, most forest area is found in large patches 

(≥1,000 ac), with nearly all native forest occurring in 

patches greater than 1,000 ac (Conry et al. 2008) (fig. 

C1-7). Most large forest patches are formally protected, 

while smaller forest patches occur primarily as scattered 

remnants, and some secondary forests in areas have been 

converted from forest to nonforest by urban development, 

agriculture, fire, and grazing (Gon et al. 2006). 

Because all the islands considered in this report were 

predominantly, if not entirely, forested historically, 

change from forest to other land uses in effect represents 

a breaking up of once continuous forests. Today, Hawaii 

exhibits the highest percentage of land in nonforest uses 

(64 percent), followed by Guam (52 percent). The FSM 

and American Samoa have the lowest percentage of land 

in nonforest uses (12 percent and 17 percent, respectively) 

(fig. C1-8). 

Islands with higher proportions of land in nonforest 

land uses potentially have more fragmented landscapes, 

though some islands have maintained contiguous forest in 

certain regions or habitats (e.g., upland forests in Hawaii), 

while primarily converting forests to nonforest uses in 

others (e.g., lowland and coastal terrain in Hawaii). For 

example, the trajectory of forest land use and cover in 

Hawaii differs from Puerto Rico in that much of the lands 

0 10 20 30 5

Miles

Hawai`i

ounty of Kaua`i

County of Maui

City & County of Honolulu

County of

Hawai`i

Ni`ih Kaua`i

O`ahu

Moloka`i

Lana`i

Kaho`olawe

Maui

Honoluluk

k

k

k

k

k

Hilo

KailuaKona

Kaunakakai

Wailuku

Lihu`e

State of Hawai`i

Department of Land and Natural Resources

Division of Forestry and Wildlife

Date of production: April 12, 2008

Contact: Ronald Cannarella

Forest Stewardship Program

Spatial Analysis Project

3 k

161°0'0"W 159°0'0"W 157°0'0"W 155°0'0"W

22°0'0"N

21°0'0"N

20°0'0"N

19°0'0"N

Main

Hawaiian Islands

 8 = less than 300 acres

 9 = from 300 to 1,000 

 acres

10 = more than 1,000 

 acres

 Major roads

Forest Patch

Size

Data source: Derived from

Hawai’i GAP landowner map,

GAP National Program, and 

State of Hawai’i GIS. We 

created three classes of patch

size: less than 300 acres; 

from 300 to 1,000 acres; and 

more than 1,000 acres.

Assumptions: forest patch size

is generally not considered of

importance for evaluating 

Hawai’i Forest Stewardship 

Projects. Patches of contiguous forest more than 1,000

acres in area receive the

highest value of 10 points.

Honolulu

au C

Figure C1-7. Forest patch size in the main Hawaiian Islands (Conry et al. 2008). GIS = geographic information system; 

GAP = Gap Analysis Program.
Assessing Forest Sustainability in the Tropical Forests of the United States II–13

100

90

80

70

60

50

40

30

20

10

0

Land cover (percent)

Nonvegetated/barren

Urban

Nonforest vegetation

Forest vegetation

Micronesia

Palau

U.S. Virgin Islands

Northern Marianas

Puerto Rico

Hawaii

Guam

Marshall Islands

American Samoa

Figure C1-8. Distribution of land cover by jurisdiction. Source: for Hawaii, Gon et al. 2006; for all 

others, U.S. Forest Service Forest Inventory and Analysis.

in Hawaii that were converted historically from forest to 

agriculture continue to be farmed and grazed today, while 

a significant portion of converted agriculture and grazing 

lands in Puerto Rico have been abandoned and are in the 

process of secondary succession, in part accounting for 

the higher proportion of small forest fragments.

Indicator 1.04

Species Diversity

Identifying and monitoring forest-associated species is 

important to understanding forest diversity across the 

islands, and tracking changes in species numbers is crucial for understanding critical components of forest health 

and productivity. Data on the number and richness of 

forest species are difficult to find for most of the islands, 

excepting Hawaii, Puerto Rico, and the USVI. Although 

the islands do not demonstrate high rates of species 

richness, in comparison to mainland tropical areas, for 

example, many do demonstrate high levels of endemism, 

which correlates with their isolation, climate, and heterogeneity of habitats. Hawaii, in particular, has exceptionally high numbers of endemic species. Conversely, given 

their proximity to other islands in the Caribbean and the 

American mainland, Puerto Rico and the USVI demonstrate comparatively lower levels of species endemism.

In Hawaii, more than 23,000 species have been documented, including more than 7,000 endemic forest-associated species (table C1-5). Endemism is very high among 

most Hawaiian taxa, at more than 99 percent of terrestrial 

insects, spiders, and land snails; 90 percent of plants; and 

more than 80 percent of breeding birds (Mitchell et al. 

2005). Also endemic to Hawaii, the Hawaiian hoary bat 

(Lasiurus cinereus semotus) is the only native terrestrial 

mammal. Hawaii has one native terrestrial reptile, the 

Hawaiian blind snake (Ramphotyphlops braminus), but 

no native amphibians. 

More than 10,000 terrestrial plant and animal species 

have been documented in Puerto Rico and the USVI. 

Naturalized nonnative plant and animal species comprise 

a significant portion of these islands’ biota. About half 

the forest-associated mammals are bats, while the other 

half are nonnative species such as the introduced Indian 

mongoose (Herpestes auropuctatus) and feral pigs, cats, 

and dogs. Forest-associated amphibian species in Puerto 

Rico exhibit high levels of endemism. The relatively large 

number of documented bird species in these islands is 

attributed to their importance as wintering and breeding 

grounds for migratory bird species, many of which 

depend on forests for habitat and food (Gould et al. 

2007, Joglar 2005). 
II–14 Assessing Forest Sustainability in the Tropical Forests of the United States

Indicators 1.05 and 1.06

Species at Risk of Extinction and 

Related Conservation Efforts

Identifying forest-associated species that are at risk of 

extinction and developing efforts to protect and conserve 

them are important factors in understanding and protecting forest diversity, health, and vitality. The International 

Union for the Conservation of Nature (IUCN) documents 

and lists globally extinct and threatened species in its Red 

List database (http://www.iucnredlist.org). The IUCN Red 

List is based on standard criteria with quantitative thresholds for population and range size, structure, and trends 

that are used to assign species to categories of extinction 

risk, ranging from “Least Concern” to “Critically Endangered,” as well as “Extinct in the Wild” and “Extinct” 

(IUCN Standards and Petitions Subcommittee 2013). 

Individual species are the primary unit of analysis for 

IUCN Red List data, such that candidate species are first 

identified and then assessed in terms of their population 

numbers, geographic range, habitat availability, and other 

factors. The juxtaposition of the IUCN species-specific 

process with the location-specific analysis used in this 

report is not simple or direct (IUCN 2003). Specifically, 

the IUCN data cited here do not track local extirpations 

Table C1-5. Number of documented species and native-forest-associated species for major 

taxonomic groups in the U.S. Virgin Islands, Puerto Rico, and Hawaii (endemism [E] noted in 

parentheses) 

U.S. Virgin Islands Puerto Rico Hawaii Documented Forest-associated Forest-associated endemic Documented Forest- associated Forest-associated endemic Documented (Native) Forest-associated

Forest- associatedendemic

Mammals—terrestrial 38 16 0 45 13 0 20 1 1

Birds 232 99 1 320 154 19 274 37 33

Fish—freshwater 7

 (0 E)

N/A N/A 37

(7 E)

N/A N/A 45 5 5

Amphibians 8 8 1 24 15 12 4 0 0

Reptiles 22 18 3 55 

(44 E)

N/A N/A 18 1 1

Insects 1,769

(6 E)

N/A N/A 5,373 

(1,518 E)

N/A N/A 7,902 ~5,000 >99%

Plants—vascular ~900 N/A N/A 3,126

(240 E)

N/A N/A 2,597 1,233 981

Source: Acevedo-Rodriguez 1996, Eldredge and Miller 1995, Gould et al. 2008, Infonatura 2007, Joglar 2005, Liogier and Martorell 1998, 

Mitchell et al. 2005, Pyle 2002, Riegl and Dodge 2008, Suárez Zapata 2014, Weaver 2006.

N/A = not available.

of listed species and may not reflect all occurrences of all 

extinct and at-risk species. Nevertheless, the IUCN Red 

List is an important and widely cited global database on 

at-risk species, and it is unique in its provision of information for all island jurisdictions included in this report. 

Because the islands included in this report were originally 

predominately to entirely forested in accordance with 

predicted forest distribution arising from the Holdridge 

Life Zones classification system (see fig. C1-2) (Ewel 

and Whitmore 1973, Tosi et al. 2002), we report the 

total number of native terrestrial species listed by the 

IUCN in categories of extinction and at-risk of extinction 

(extinct in the wild, critically endangered, endangered, 

vulnerable, near threatened) (table C1-6). The IUCN lists 

473 terrestrial animal and 409 terrestrial plant species 

at risk of extinction or already extinct across the United 

States and U.S.-affiliated islands included in this report, 

not including taxa known to have become extinct prior 

to 1500 CE nor “undescribed species assessed as data 

deficient” (IUCN 2015). Greater numbers of listed species 

are generally associated with larger land areas. Of the 

islands considered herein, Hawaii encompasses the 

greatest numbers of species listed as extinct (89 percent 

of total) and at-risk of extinction (49 percent of total) by 

the IUCN. Additionally, Hawaii accounts for 69 percent 
Assessing Forest Sustainability in the Tropical Forests of the United States II–15

Table C1-6. Number of Terrestrial IUCN Red List species native to U.S. and U.S.-affiliated tropical islands 

per at-risk category

IUCN categories Kingdom

Extincta Extinct 

in wild

Critically 

endangered Endangered Vulnerable

Near 

threatened Animalia Plantae

U.S. Virgin Islands 2 0 10 11 5 7 22 13

Puerto Rico 4 0 35 33 28 18 55 63

Hawaii 109 7 204 87 62 16 175 310

American Samoa 1 0 2 9 10 5 24 3

Marshall Islands 0 0 0 3 4 8 15 0

Micronesia 2 0 6 12 11 17 43 5

Northern Marianas 0 0 9 11 9 8 32 5

Guam 3 2 8 13 9 11 42 4

Palau 1 0 27 16 8 19 65 6

United Statesb 157 10 263 200 298 202 675 458

a Known extinctions of documented species since 1500. Known species that are missing and can no longer be found but which cannot be confirmed as 

extinct are flagged as “possibly extinct” within the “critically endangered” category.

b For reference; includes Hawaii.

Source: International Union for Conservation of Nature (IUCN) 2015 Red List of Threatened Species online database (http://www.iucnredlist.org/).

of the species listed as extinct and 39 percent of the listed 

at-risk species of the entire United States. Animal species 

listings outnumber listed plant species, except in Hawaii 

and Puerto Rico. In the Pacific Islands, birds dominate the 

IUCN lists of species, with the exception of Palau, where 

a majority of the listed species are gastropods (snails and 

slugs). In the Caribbean, the number of IUCN-listed bird 

species is relatively balanced by listed amphibians and 

reptiles. 

Island extinction rates are generally higher than continental rates in the same latitudinal belt, in part because 

island species typically have small populations, restricted 

genetic diversity, and narrow geographic ranges, making 

them more susceptible to impacts from natural and 

anthropogenic disturbances (MacArthur and Wilson 1967, 

Vitousek 1988). Notably, Hawaii represents less than 1 

percent of the total area of the United States, but possesses 

a majority of its documented plant and animal extinctions. 

Prehistorically, innumerable native Hawaiian species went 

extinct under natural conditions, but extinctions have 

accelerated since initial human contact from 800 to 1,600 

years ago. For example, nearly 10 percent of recorded 

Hawaiian plants are presumed to be extinct. In addition, 

sixteen named forest bird species have gone extinct in 

historical times, another two forest bird species are presumed extinct (i.e., Hemignathus ellisianus procerus = H. 

procerus (other H. ellisianus subspecies also considered 

extinct); Pareromyza flammea) and seven more birds are 

likely extinct (i.e., Hemignathus lucidus, Melamprosops 

phaeosoma, Moho braccatus, Myadestes lanaiensis, M. 

myadestinus, Paroreomyza maculate, Psittirostra psittacea, not including Corvus hawaiiensis) (Eldredge and 

Miller 1995, Pyle and Pyle 2009). These extinctions are 

driven by a complex array of factors, including historical 

hunting by native islanders and European colonizers, 

predation by introduced species, introduced diseases, and 

habitat loss and fragmentation, all of which are exacerbated by limited genetic diversity, particularly as endemic 

populations decreased in size and range (Groombridge 

2008). On small islands with native fauna that have 

evolved largely without predators, extinctions may be 

driven by the introduction of a single species. For example, the introduced brown tree snake (Boiga irregularis) is 

considered to be responsible for the extirpation of nine of 

Guam’s 11 native forest-dwelling birds (Fritts and Rodda 

1998).

In the Caribbean islands, the number of known extinctions since human contact is relatively low, in spite of 

significant changes in land use over the past century or 

so. Specifically, human activity reduced the area of native 

forest in Puerto Rico to less than 5 percent by the 1940s, 

but given the use of shade trees in the coffee region and 

the growth of secondary forest patches throughout the 

island, forest cover never fell below 10 to 15 percent, contributing significantly to the protection of fauna and flora 

species (Lugo 1988). For example, for the first 500 years 

of colonization in Puerto Rico, Brash (1984) documented 

the extirpation of seven known bird species (12 percent 

of originally documented bird fauna), including four 

endemic species, while during the same period the total 
II–16 Assessing Forest Sustainability in the Tropical Forests of the United States

population of species increased because of the naturalization of nonnative species. By the 1980s, there were more 

breeding birds species present on the island (97 species) 

than in pre-Colombian times (60 species) (Brash 1984). 

Nonetheless, a small but increasing number of bird species 

in Puerto Rico and the USVI are threatened by habitat 

destruction, degradation, and fragmentation; predation by 

introduced and other species; and increasing susceptibility 

to parasitism and disease (IUCN 2008, Joglar 2005, Lugo 

et al. 2012).

The threat of extinction is more severe for several 

Caribbean species of amphibians and reptiles, such as 

the golden coqui (Eleutherodactylus jasperi), a species 

of frog endemic to Puerto Rico that is the only known 

live-bearing species from the Leptodactylidae family. 

It was last seen in 1981 (Hedges and Joglar 2004) and is 

listed as critically endangered by the IUCN (2013) and 

as threatened under the U.S. Endangered Species Act 

(ESA) (USFWS 2008). Similarly, the Virgin Islands coqui 

(Eleutherodactylus schwartzi) is thought to be extirpated 

from the Virgin Islands, surviving only on the British 

Virgin Islands of Tortola and Virgin Gorda (Kaufman 

and Mallory 1993). The St. Croix racer (Alsophis sanctaecrucis), a snake endemic to the USVI, was last seen in 

the early 1900s, and is now considered extinct (Kaufman 

and Mallory 1993). Many forest-associated amphibian and 

reptile populations in these islands have been negatively 

affected by habitat destruction, forest fragmentation, 

limited distribution, high habitat specialization, slow 

reproduction, introduced predators, and infectious disease—many of which are being exacerbated by changes in 

climate (Burrowes et al. 2004, IUCN 2008). 

Under the provisions of the ESA, the U.S. Fish and 

Wildlife Service (USFWS) identifies and lists plant and 

animal species considered to be at risk of extinction in 

the United States and affiliated jurisdictions. At-risk 

forest-associated species have been listed by the USFWS 

in the USVI, Puerto Rico, Guam, the Marshall Islands, 

and Hawaii. Although there is some overlap of species 

listed by the USFWS and the IUCN, neither list is entirely 

inclusive of the other for any jurisdiction. As of 2010, 503 

plant and animal species in Hawaii, Puerto Rico, and the 

USVI were listed as endangered, threatened, or candidate 

species for listing by the USFWS (table C1-7). More than 

three-fourths of these at-risk species are plants. Moreover, 

many of the species listed by the USFWS are endemics, 

such that their extinction within the jurisdiction would 

mean extinction of the global population and a permanent 

loss of biodiversity. 

A wide array of on- and offsite efforts to protect at-risk 

forest species and their diversity has been established 

throughout the islands. For example, the USFWS prepares, coordinates, and implements species recovery 

plans and critical habitat designations for the prevention 

of the extinction of listed species, in coordination with 

other federal agencies and partners, as part of its administration and implementation of the ESA. Many such 

plans and habitats are found throughout the United States 

and U.S.-affiliated tropical islands. Many at-risk animal 

and plant species are the subjects of additional, and in 

some cases, considerable in-situ and ex-situ conservation 

efforts throughout the islands. These efforts include the 

protection and restoration of habitat; captive breeding and 

reintroduction of captive-born species; and research, education, and outreach. For example, numerous at-risk tropical plant species are conserved ex-situ in the Center for 

Plant Conservation’s National Collection of Endangered 

Plants, including 96 at-risk plant species native to Hawaii, 

Table C1-7. Endangered (E), threatened (T), and candidate (C) forest-associated species 

listed by the U.S. Fish and Wildlife Service in Hawaii, Guam, the Marshall Islands, Puerto 

Rico, and the U.S. Virgin Islands in 2010

U.S. Virgin 

Islands Puerto Rico Hawaii

Marshall

Islands Guam

E T C E T C E T C E T C E T C

Mammals 1 1 1 1

Birds 2 2 1 8 2 1 24 6 6

Amphibians 1 3

Reptiles 2 3 2

Snails 41 1 3

Plants 4 4 45 5 4 273 7 46 3 1 1

Source: USFWS 2008.
Assessing Forest Sustainability in the Tropical Forests of the United States II–17

21 species native to Puerto Rico, and 6 species native 

to the USVI (CPC 2008). Through participating partner 

botanical institutions, the center collects and maintains 

“plants, seeds, cuttings, and other plant material.” 

The Puerto Rican parrot (Amazona vittata)—considered 

one of the 10 most endangered bird species in the world—

represents an example of extensive conservation efforts 

(Birdlife International 2008a). Once prevalent in Puerto 

Rico, this species was nearly extirpated by the 1950s having been reduced to about a dozen birds in the wild. The 

Puerto Rican parrot was federally listed as an endangered 

species in 1967 under the Endangered Species Preservation Act of 1966 and later protected under the Endangered 

Species Act of 1973 (USFWS 2008). Significant efforts to 

preserve the species began in 1968, including experiments 

with artificial nest sites, control of nest predators and 

competitors, captive breeding, captive-bred bird reintroductions, and radiotelemetry monitoring of reintroduced 

species. Today, the USFWS works closely with the Forest 

Service and the Puerto Rico Department of Natural and 

Environmental Resources through collaborative efforts 

to preserve the parrot, including threats management, 

captive breeding, and release of captive-bred parrots 

into the wild. As of 2013, there were nearly 400 parrots 

in captivity and more than 100 being tracked in the wild 

across the island, up from 225 in captivity and about 40 in 

the wild in 2008.

Indicators 1.07, 1.08, and 1.09

Genetic Diversity, Its Status, and 

Related Conservation Efforts

Genetic diversity within and across species is an important factor in forest health and productivity. For most 

of the islands, the vast majority of forest-associated 

species at risk of extinction also are at risk of losing 

genetic variation, particularly given the isolation and 

remoteness of most of these areas. In particular, species 

that encompass many subspecies or a wide variety of 

genotypes are vulnerable to losses in genetic diversity 

as populations decline. This is a common characteristic 

of many Hawaiian species that have a broad geographic 

range within which evolution and adaptive radiation have 

taken place in local niches (without completely separating 

into distinct species). These subspecies and genotypes 

are subject to the same threats as species at risk: habitat 

loss to development, nonnative species, fire, and loss of 

pollinators or other symbiotic species, and their decline or 

loss represents crucial losses in genetic diversity. 

Many forest-associated species currently are found on 

fewer islands or in fewer locations than their original 

distribution, largely because of land use changes and the 

associated loss of native forests, which have likely led to 

the loss of locally adapted genotypes. For some species, 

information is available concerning historical ranges 

and current ranges; for others, historical ranges might 

be extrapolated from climate and soils data as well as 

palynology. Nonetheless, a comprehensive summary of 

the percentage of species occupying a given portion of 

their original range was not available for any of the islands 

at the time of this study. 

As an example, Hawaii’s Acacia koa, a dominant native 

forest tree species, displays a great deal of genetic 

diversity and numerous subspecies. Yet, its range has been 

substantially reduced by forest conversion and harvesting 

(fig. C1-9), indicating potential loss in its genetic diversity. Subspecies of A. koa are not listed for protection 

under state or federal law except as local populations are 

protected in reserves. Similarly, sandalwood (Santalum 

spp.) shows significant genetic diversity within the 

Hawaiian Islands, including at least six distinct species 

and several subspecies radiating from two colonization 

events. Land use changes, invasive nonnative species that 

modify habitat, and unsustainable harvesting practices 

have resulted in the reduction in habitat range of sandalwoods in Hawaii, and throughout other parts of the Pacific 

Basin. One species of Hawaiian sandalwood (Santalum 

involutum) is currently proposed for listing under the ESA 

as endangered, and one subspecies is already listed as 

endangered. Conservation efforts are focused on maintaining the genetic diversity of sandalwood and preventing 

hybridization between species throughout the Pacific, 

particularly given the high commercial value of several 

sandalwood species, 

Species- and subspecies-specific genetic conservation 

measures are developed and carried out for several of the 

at-risk species listed by the USFWS under the ESA, and 

for many of the threatened animal species listed by the 

IUCN. Some species, such as the Puerto Rican parrot 

and the Hawaiian palila (Loxioides bailleui) and small 

Kauaʻi thrush (Myadestes palmeri), have been the subject 

of long-term and intensive efforts that include genetic 

conservation through captive breeding and release into the 

wild. Some at-risk plant species have also been the subject 

of genetic conservation efforts, largely through preservation and cultivation in local and international botanical 

gardens. 
II–18 Assessing Forest Sustainability in the Tropical Forests of the United States

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Hawaii Community College
Assessing Forest Sustainability in the Tropical Forests of the United States II–25

Criterion 2

Assessing Forest Sustainability in the Tropical Forests of the United States

Maintenance of the Productive Capacity of Forest Ecosystems

Kathleen A. McGinley

Introduction

Many tropical island communities depend on forests 

directly or indirectly for a wide range of extractive and 

nonextractive goods and services. Some of these goods 

and services are essential for human survival; others 

are important to an enhanced quality of life. Tropical 

island forests harbor a vast diversity of trees, other 

plants, animals, and other organisms that can be used and 

harvested regularly as renewable resources. However, if 

use or harvest levels exceed resource growth and replacement, there is the potential for ecosystem change or even 

decline. To sustain use and harvests over time, island 

forests must be sufficiently productive to maintain natural 

processes and grow raw materials in excess of their use 

and removal. 

Productive capacity of forest ecosystems refers to the 

ability of forests to produce goods and services for 

humans. It is a human-derived value and overlaps the 

economic, social, and environmental realms. Criterion 2 

specifically addresses the capacity of forests to produce 

extractive goods and services, including wood products 

such as sawlogs, pulpwood, construction materials, and 

fuelwood, and nontimber forest products (NTFPs) such 

as medicinal plants, food, forage, and arts and crafts 

supplies. Tropical island forests also obviously provide 

environmental services and socioeconomic benefits, 

which are addressed under other criteria in this report.

Determining sustainable harvest levels requires monitoring and assessment of the forest system in its entirety to 

determine if changes in the productive capacity of forests 

may be a signal of unsound forest management practices 

or other unforeseen agents affecting forest systems. 

Although efforts to systematically measure and monitor 

forests under the U.S. Forest Service’s Forest Inventory 

and Analysis (FIA) program have been established on 

most of these islands, systematic measurement and 

monitoring of timber and nontimber extractive activities 

is mostly absent. 

Criterion Summary

Most of the islands considered in this report were once 

nearly completely forested, and all have experienced 

differing degrees of forest conversion to other land uses. 

More recently, as agriculture and other land uses have been 

abandoned, there has been an increasing reversion 

of converted forest lands to secondary forests. Today, 

all the island jurisdictions are more than 50-percent 

forested, with the exception of Hawaii and Guam (35- and 

48-percent forested, respectively). However, across the 

islands, most forests are dominated by relatively small 

trees (<11 inches diameter at breast height [dbh]), owing to 

both natural and human-induced disturbance regimes that 

result in few forest stands with enough big trees for viable, 

large-scale timber production.

Very little commercial harvest of natural or planted forests 

occurs on any of the islands, with the exception of Hawaii, 

where there is an established but small (and growing) 

timber industry and a discernible area of active forest 

plantations (4.7 percent of total forest area). Across the 

islands, forests are perhaps most valued for water and soil 

conservation, cultural and spiritual values, recreation, and 

noncommercial forest products such as fuelwood, canoe 

and construction resources, arts and crafts materials, 

and wild game. Overall, it appears that forest growth far 

exceeds forest harvests in most cases, though some select 

forest resources in Hawaii (e.g., Acacia koa and Santalum

spp. from natural forest stands) and in the Federated States 

of Micronesia (FSM) (e.g., fuelwood from mangrove 

forests) are under an increasing threat of overharvesting.

In many cases, the increasing area and growth of secondary forest eventually may represent a potentially 

significant timber source, though forest protection for 

water and soil conservation and other nonextractive uses 

remains a primary objective on most islands. Additionally, 

agroforestry practices that combine trees and shrubs with 

agriculture or livestock are fairly common across most of 

the islands and represent another potential timber source. 

In Puerto Rico, for example, shade coffee systems that 

integrate timber species are seeing a resurgence. And, 

in the Pacific, agroforestry techniques have long been practiced and constitute a traditional land use that can result in 

more diverse, productive, and profitable land use systems 

than conventional monocultures.
II–26 Assessing Forest Sustainability in the Tropical Forests of the United States

The Indicators

Criterion 2 of the Montréal Process Criteria and Indicators 

(MP C&I) contains five indicators, which are focused on 

forest productivity in relation to actual production levels 

of timber and NTFPs. Because of ongoing forest inventory 

activity conducted by the FIA program (see also chapter 

1), there is fairly good data coverage for standard forest 

measures across the islands, but less so for NTFPs. Owing 

to the extent and quality of this data coverage and the 

importance of forest inventory information to the other 

criteria considered in this report, we treat each of the 

Montréal Process indicators in Criterion 2 separately.

• 2.10: Area and percentage of forest land and net area 

of forest land available for wood production. 

• 2.11: Total growing stock and annual increment of 

both merchantable and nonmerchantable tree species 

in forests available for wood production. 

• 2.12: Area, percentage, and growing stock of plantations of native and exotic species.

• 2.13: Annual harvest of wood products by volume 

and as a percentage of net growth or sustained yield. 

• 2.14: Annual harvest of nonwood forest products. 

Indicator 2.10

Forest Land Available For 

Wood Production

Most of the island jurisdictions have extensive forest 

cover—all but Hawaii and Guam are more than 50-percent forested. However, other than Hawaii, where there 

is an established, small timber industry, very little of the 

total forest area in any jurisdiction is actively managed 

for timber or other wood products. Additionally, significant areas of forest are formally protected or otherwise 

unavailable for wood production on many of the islands. 

Current, direct measures of forest land available for 

wood production are not available for any of the islands, 

but indirect measures provide an estimate of potentially 

productive forest land. 

In the Caribbean islands, very little of the available wood 

volume is harvested, and there is no indication that this 

situation will change in the foreseeable future. In the U.S. 

Virgin Islands (USVI), which was 55-percent forested in 

2009, forested land is increasing as agricultural activities 

decrease (Brandeis and Turner 2013b). However, there 

is competition for these lands from other, nonforest land 

uses (e.g., development). Few forests are harvested for 

timber or other wood products, and there is limited, if 

any, commercial wood production (Brandeis and Oswalt 

2007). The actual area of forest land available for wood 

production in the USVI is unknown, but given the protected status of some forests, the large portion (59 percent) 

of forest in the subtropical dry forest life zone, which is 

dominated by slower growing, smaller trees, and other 

limiting factors, a relatively small portion of the total 

forest area in the USVI is potentially available for wood 

production. 

In Puerto Rico, recent forest inventories do not measure 

forest area available for wood production, but forest inventories in 1980 and 1990 did delineate potential areas for 

commercial wood production on the main island of Puerto 

Rico based on site productivity and land use. Excluded 

from these measurements were mountainous regions 

where excessive slopes or rainfall limit operability, the 

subtropical dry forest region where rainfall is less than 

1000 mm (37.39 inches) per year, areas with unproductive 

soils, and areas with land uses not compatible with commercial wood production (e.g., protected, urban, critical 

watersheds) (Birdsey and Weaver 1982, Franco et al. 

1997). The commercially designated forest inventory area 

in 1990 was about 437,000 ac, of which 34 percent was 

forested (about 148,000 ac). The commercially designated 

forest area in 1990 was mostly found in the subtropical 

moist and wet forest life zones, primarily in upland, nonurban areas between the valleys dedicated to agricultural 

production and higher mountain areas with steep slopes 

that are primarily reserved for watershed protection and 

other functions. A minute fraction of this forest area is 

actively managed for timber today.

Forests cover nearly 1.5 million ac of Hawaii (about 36 

percent of its total land area), including more than 70,000 

ac of forest plantations, which comprise forests planted for 

the primary purpose of timber production, as well as forests planted for the primary purpose of watershed protection (Gon et al. 2006, Little and Skolmen 1989, Matsuwaki 

2015). Gon et al. (2006) identified 504,607 ac (34 percent 

of all forest) from 1999–2005 Landsat Thematic Mapper 

satellite data as being within Hawaii Gap Status 4, which 

is defined as “an area lacking a mandate to prevent conversion of natural habitat types to anthropogenic habitat 

types; where intensive use allowed throughout the tract; 

and includes those tracts for which the existence of such 

restrictions or sufficient information to establish a higher 

status is unknown.” Thus, the area of forest classified as 

Hawaii Gap Status 4 by Gon et al. (2006) is expected to be 

available for wood production provided that accessibility, 

stand and site conditions, and other factors critical for 
Assessing Forest Sustainability in the Tropical Forests of the United States II–27

timber production viability are met. Note that this does 

not include pasture lands with potential for reforestation. 

It also does not include the 738,983 ac of mostly forest 

reserves classified as Hawaii Gap Status 3, which is 

generally unavailable for timber production, even though 

it may be subject to artisanal extraction for canoes and 

other products (i.e., “an area having designated protection 

from conversion of natural land cover for the majority of 

the area, but subject to extractive uses of either a broad, 

low-intensity type or localized intense type” (Gon et al. 

2006).

In recent forest inventories of the U.S.-affiliated Pacific 

islands, Donnegan et al. (2004a, 2004b; 2007; 2011a, 

2011b, 2011c) measured the potential productivity of 

forest land based on a topographic relative moisture index 

(TRMI) that takes into account the potential of a site to 

retain moisture relative to the soil-based forest type. The 

majority of forest land in Guam, the Northern Marianas, 

Palau, and American Samoa was classified as demonstrating relatively high potential for forest productivity 

in terms of soil moisture retention (74, 58, 58, and 57 

percent, respectively). Thirty-six percent of the forest 

area in the FSM was classified as such. Nevertheless, 

a significant proportion of the terrain on these islands 

is steeply sloped, in karstic regions, or encompasses 

shallow, porous soils that prohibit or significantly limit 

the potential for commercial timber extraction (i.e., about 

50 percent of American Samoa and Palau and at least 25 

percent of Guam) (Donnegan et al. 2004a, 2004b; 2007; 

2011a, 2011b, 2011c). Moreover, formal protection of 

forests is increasing throughout these islands, particularly 

under agreements made through the Micronesia Challenge 

(PCS and TNC 2011) (also see Criterion 1).

Indicator 2.11

Forest Growing Stock

Forests typically are dominated by younger trees of 

smaller diameter with a mixture of native and nonnative 

species across most of the jurisdictions addressed in this 

report. Much of the wood in these forests currently is not 

suitable for solid wood products, but may be so in the 

future depending on stocking, growth rates, and applied 

management practices. 

In the Caribbean islands, forests cover more than half of 

the landscape, though the majority of these forests are 

young (<25 years), and a very small portion is dominated 

by merchantable timber trees. The forests generally are 

increasing in terms of basal area and volume as they grow 

into older stands with more medium- and large-diameter 

trees (Brandeis and Turner 2013a, 2013b). 

The vast majority of the trees in Puerto Rico’s forests 

are small (<5 inches dbh) (table C2-1). Although larger 

diameter trees make up a relatively small percentage of 

the total number of trees in the forest, they account for 

most of the measured merchantable volume. Additionally, 

as growth continues to exceed mortality and removals in 

Puerto Rico, growing stock volume also is rising. These 

high growth rates are due in large part to the rapid growth 

characteristics of young forest stands (Brandeis and 

Turner 2013a). 

Similarly to Puerto Rico, most of the forests in the USVI 

are young and follow a pronounced reverse-J diameter 

distribution (Brandeis and Oswalt 2007, Brandeis and 

Turner 2013b). Although the average forested acre in the 

Table C2-1. Forest stocking data on U.S.-affiliated Caribbean and Pacific islands, 2004–2013 

U.S. Virgin 

Islands

Puerto 

Rico

American 

Samoa

Marshall 

Islands Micronesia

Northern 

Marianas Guam Palau

Total number of trees (millions) 85 1,460 18 12 94 90 77 97

Total number of trees per acre 1,882 1,250 413 516 655 1,193 1,206 1,069

Total number of trees ≥5 inches 

dbh (millions) [percentage of 

total trees]

3 [0.1] 132 [9] 6 [36] 4 [30] 27 [29] 6 [7] 10 [13] 10 [11]

Average number of trees 

≥5 inches dbh per acre

60 109 133 111 168 118 74 95

Total net volumea

 (million ft3) 15 1,276 66 54 571 35 58 265

Average net volume per acre 

(ft3

/acre)

176 1,052 1,657 1,624 3,530 687 1,431 3,334

a

 Net volume is the cubic volume of all trees >5 inches in diameter less the cubic volume from damage and rotten defects.

dbh = diameter at breast height.

Source: U.S. Forest Service Forest Inventory and Analysis.
II–28 Assessing Forest Sustainability in the Tropical Forests of the United States

USVI contains more trees than in Puerto Rico (1,882 vs. 

1,250 trees/ac; respectively), about 80 percent of the total 

forested area in the USVI is dominated by trees less than 

5 inches dbh. Consequently, a very small percentage of 

trees are considered growing stock in the USVI, and there 

is significantly less merchantable growing stock in the 

USVI than in Puerto Rico (Brandeis and Oswalt 2007, 

Brandeis and Turner 2013b) (fig. C2-1). Moreover, the 

potential for large-scale timber production in the USVI 

is relatively limited given the predominance of forests in 

dry forest life zones, which maintain slower growth rates 

and smaller diameter trees (table C2-1). 

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

0

Average net volume (cubic feet per acre)

Micronesia

Palau

U.S. Virgin Islands

Northern Marianas

Puerto Rico

Guam

Marshall Islands

American Samoa

Figure C2-1. Average net volume in cubic feet per acre of live 

trees ≥1 inch diameter at breast height on forest land.

Forests dominate much of the landscape in the Pacific, 

with Guam and Hawaii being the only jurisdictions in 

this report that are less than 50-percent forested (48 

and 36 percent, respectively). Similarly to forests in the 

Caribbean, most Hawaiian and Pacific Island forests 

exhibit a reverse-J pattern diameter distribution. As in the 

Caribbean, these structural characteristics are closely tied 

to natural disturbance processes, such as fire, typhoons, 

and tropical storms, and to historical and current land 

use practices that lead to secondary forest growth (e.g., 

forest clearing for agriculture or settlement, which, after 

abandonment, is followed by forest recolonization (Cram 

et al. 2013; Donnegan et al. 2004a, 2004b, 2007, 2011a, 

2011b, 2011c) (table C2-1; fig. C2-1). The secondary forest 

understory is increasingly dominated by nonnative woody 

species, which may become invasive and outcompete 

natives, particularly in Hawaii (Ainsworth and Kauffman 

2010, Cordell et al. 2009). 

There were no comprehensive forest maps for the islands 

of Hawaii, nor was there a complete statewide forest 

inventory available when this report was prepared. 

Consequently, no estimates of total growing stock or 

growth rates of all merchantable and nonmerchantable 

tree species were available for Hawaii. Inventory data and 

extrapolations from about 24,000 ac of planted forest on 

state lands in Hawaii in the late 1990s reported an estimated 78.2 million ft3

 of merchantable timber from about 

a dozen nonnative species, including species of the genera 

Eucalyptus, Grevillea, Melaleuca, Acacia, and Casuarina

(Constantinides and Canarella 1999, 2001; Constantinides 

et al. 2000a, 2000b; Little and Skolmen 1989). 

Overall, of the islands inventoried, the Marshall Islands 

exhibit the highest proportion of forested area dominated 

by the largest trees (60 percent: 11 to 20.9 inches dbh). 

The forests of the FSM demonstrate the greatest net volume per acre (Donnegan et al. 2004a, 2004b, 2007, 2011a, 

2011b, 2011c). The dominance of comparatively larger 

trees in the Pacific Islands is frequently attributed to the 

presence of coconut trees (Donnegan et al. 2004a; 2007, 

2011b), which often occur at high densities in mature 

plantations. And, although larger trees (>21 inches dbh) 

are found in many forest stands, very little of the total 

forested area of the Pacific Islands is dominated by trees 

greater than 21 inches dbh. In Guam and the Northern 

Marianas, forests tend to be dominated by smaller trees, 

owing to frequent disturbance by typhoons, and more 

recently to human-induced land use changes. Notably, 

the most recent forest inventory of Guam found no trees 

greater than 20 inches dbh (Donnegan et al. 2004b).

Indicator 2.12

Plantations of Native and 

Exotic Species

Plantations of nonnative (and more recently, native) timber 

species have been planted on many islands as far back as 

at least the early 1900s. Today, more than 80,000 ac of 

planted forest are found on these islands, 86 percent of 

which are found in Hawaii (table C2-2). Across all jurisdictions, plantations are primarily stocked with nonnative 

timber species, including Eucalyptus spp., Swietenia spp., 

and Tectona spp., though there is increasing interest and 

investment in native species reforestation, particularly 
Assessing Forest Sustainability in the Tropical Forests of the United States II–29

for restoration of degraded lands. Data on plantations are 

available for the Caribbean and three jurisdictions in the 

Pacific (table C2-2). Although most U.S.-affiliated Pacific 

islands have some, albeit very limited planted forest 

area, there were no readily available data on their extent, 

merchantable volume, or growth rates as of 2010.

Following decades of forest clearing in Puerto Rico, 

extensive reforestation with nonnative and native species 

began in earnest in the early 1930s (Weaver 2012). As of 

1995, Puerto Rico had about 9,900 ac of planted forests on 

public and private lands. Planted species include mahogany (Swietenia spp.), teak (Tectona grandis), eucalyptus 

(Eucalyptus spp.), Caribbean pine (Pinus caribea), María 

(Calophyllum antillanum), and mahoe (Hibiscus elatus) 

(Francis 1995). About one third of the total planted 

acreage was established in the El Yunque National Forest 

(a.k.a. Luquillo Experimental Forest), where trials with 

West Indies mahogany (Swietenia mahagoni), Honduran 

mahogany (Swietenia macrophylla), and hybrids (Swietenia macrophylla × S. mahagoni) were conducted (Bauer 

and Gillespie 1990). Francis (1995) reported a range in 

average annual volume increments for the major timber 

species planted on “better than average sites” in Puerto 

Rico, ranging from 29 to 114 ft3

/ac/year for Swietenia 

mahagoni to 400 to 600 ft3/ac/year for Pinus caribea.

In the USVI, there are about 270 ac of planted forests on 

St. Croix, composed mostly of teak (Tectona grandis), 

Spanish cedar (Cedrela odorata), West Indies mahogany 

(Swietenia mahagoni), Honduran mahogany (Swietenia 

macrophylla), and hybrids of the latter two species 

(Swietenia macrophylla × S. mahagoni) (Somberg 1976, 

Weaver and Francis 1988). There is no information on 

annual volume increments for these planted species. 

St. John and St. Thomas do not have any documented 

measureable planted forest area. 

No new plantations have been established in the 

Caribbean jurisdictions since those documented in the 

mid-1990s. Furthermore, there is very little evidence 

that existing plantations in Puerto Rico or the USVI are 

actively managed or harvested beyond isolated extractions 

for personal or artisanal consumption. Likewise, there is 

no indication that these plantations will be extensively or 

commercially harvested in the near future. 

Forest plantations cover about 70,358 ac in Hawaii, 

accounting for almost 5 percent of the total forest area 

(Matsuwaki 2015) (table C2-3). Fifty-seven percent of 

forest plantations are on private lands, 42 percent on state 

lands, and about 1 percent on federal and county government lands (Matsuwaki 2015). The Big Island of Hawaii 

hosts 72 percent of the total planted forest area. The vast 

majority of planted forests on public lands are stocked 

with nonnative timber species, including Eucalyptus

spp., Grevillea spp., and Albizia spp. Private lands are 

stocked mostly with native and mixed (native/nonnative) 

tree species (Constantinides and Canarella 1999, 2001; 

Constantinides et al. 2000a, 2000b). Acacia koa is the 

principal native tree species used in forest plantations. 

Although some planted forests in Hawaii are intended for 

commercial timber harvests, at least half are designated 

for water and soil conservation, as well as for educational 

purposes and aesthetic values (Constantinides and 

Canarella 1999, 2001; Constantinides et al. 2000a, 2000b; 

Little and Skolmen 1989). 

Table C2-3. Planted forest area in Hawaii, 2015

Federal State Private Total

Acres

Kauai 1 3,744 230 3,975

Oahu 0 3,438 5,516 8,954

Molokai 1 1,624 1,188 2,819

Maui 9 2,646 1,490 4,145

Hawaii 188 18,371 31,906 50,465

 Total 199 29,823 40330 70,358

Source: Matsuwaki 2015.

Table C2-2. Forest plantation area and 

percentage of total forest area,a circa 2010

Planted 

forest area

Total 

forest area

Acres Percent

U.S. Virgin Islands ~270 <1

Puerto Rico ~9,900 <1

Hawaii 70,358 4.7

Guam ~840 1.3

Palau ~100 <1

a

 Only jurisdictions with data are shown here. Source: Francis 

1995, Territory of Guam 2010, Matsuwaki 2015, Republic of 

Palau 2010, Somberg 1976, Weaver and Francis 1988.

Ten nonnative timber species planted on state lands in 

Hawaii were inventoried in the late 1990s (Constantinides 

and Canarella 1999, 2001; Constantinides et al. 2000a, 

2000b). Results demonstrated that there were about 72.8 

million ft3 of merchantable stem volume across nearly 

24,000 ac (table C2-4). Planted tree species exhibited 

a wide range in growth rates (30 to 500 ft3

/ac/yr), with 

Eucalyptus spp. and Flindersia brayleyana (Queensland 

maple) demonstrating the strongest growth and site 

adaptation across the state (Constantinides and Canarella 
II–30 Assessing Forest Sustainability in the Tropical Forests of the United States

Table C2-4. Hawaiian nonnative plantation timber inventory summary data, 1999–2000

Location Area

Number 

of stands Species

Merchantable 

volume

Mean annual 

increment

Acres Thousand 

cubic feet

Cubic feet/

year

Hawaii—Waikea 12,043 228 Eucalyptus spp.; Flindersia 

brayleyana; Toona ciliata; 

Fraxinus uhdei

16,300 150–500

Hawaii— Kalopa, 

Waimea, Honuaula, 

and Kiolakaa-Keaa

1,160 40 Eucalyptus spp.; Cryptomeria 

japonica; Fraxinus uhdei; 

Casuarina eqiusetifolia

7,400 45–280

Hawaii— Hamakua 6,295 144 Eucalyptus spp.; Flindersia 

brayleyana; Toona ciliata

37,900 100–500

 Subtotal 19,498 412 61,600 45–500

Molokai 2,100 138 Eucalyptus spp.; Pinus elliottii; 

Pinus taeda

6,900 40–160

Kauai 2,390 178 Eucalyptus spp.; Pinus elliottii; 

Pinus taeda

4,300 30–300

All 23,988 728 72,800 30–500

Source: Constantinides and Canarella 1999, 2001; Constantinides et al. 2000a, 2000b.

1999, 2001; Constantinides et al. 2000a, 2000b). Pinus 

spp., Toona ciliata, Fraxinus uhdei, and most of the other 

nonnative species were not as well adapted to Hawaii’s 

site conditions. Most of the measured stands were either 

overmature or not actively managed after planting, 

indicating that reported growth rates may underestimate 

species growth potential (Constantinides and Canarella 

1999, 2001; Constantinides et al. 2000a, 2000b).

Plantation forestry occurs on a very limited basis in the 

U.S.-affiliated Pacific islands. Guam has about 740 ac of 

plantations on government-owned land and about 100 

ac of planted forests on private land (Territory of Guam 

2010). Species and provenance trials with Eucalyptus

spp. were conducted in the 1970s to select species for 

establishment in wind-exposed and sheltered sites. More 

recently, attention has turned to Acacia spp. owing to fast 

growth rates and resistance to fire. Reforestation with 

Acacia spp. is largely for restoration of degraded lands, 

while plantings of other species are primarily for timber 

production. A. auriculiformis and A. mangium are the 

principal species planted today (Territory of Guam 2010).

In Palau, about 100 ac of mostly mahogany (Swietenia 

macrophylla) have been planted on state and privately 

owned lands (Republic of Palau 2010). Additionally, 

line plantings of native and nonnative timber species 

are increasingly used in agroforestry systems on private 

lands, as state and private nursery capacity increases to 

meet the growing demand for timber species (Republic 

of Palau 2010). Although many of the other U.S.-affiliated 

Pacific islands do have established plantations, they are 

very limited in terms of area and lack data on extent, 

volumes, and growth rates.

Indicator 2.13

Harvest of Wood Products

Across the islands, forests are harvested for artisanal 

wood products and are important sources of wood for 

building and canoe materials in Hawaii and the U.S. 

affiliated Pacific islands. Hawaii is the only jurisdiction 

with any measurable, albeit limited, commercial timber 

extraction from forests. Fuelwood from forests is particularly important in many of the Pacific islands. Overall, 

forests are important sources of noncommercial wood 

products throughout the islands; although there are no 

monitoring activities or current data related to this indicator for any jurisdiction, anecdotal evidence suggests that, 

in the majority of cases, forest growth far outpaces forest 

harvest. Nonetheless, there is some evidence that harvests 

of some forest resources in Hawaii and the FSM are 

reaching or exceeding their available stock (e.g., Santalum

spp., and fuelwood from mangrove forests, respectively). 

Most of the wood products harvested from forests in 

Puerto Rico and the USVI are for artisanal purposes. 

Overall, forest growth rates are thought to significantly 

exceed the artisanal harvest of wood products from forests 

(Brandeis et al. 2007). However, there was no monitoring 

or current data on wood products harvests for these 

islands at the time this report was published. 
Assessing Forest Sustainability in the Tropical Forests of the United States II–31

Forest industry surveys carried out in the Caribbean in the 

mid-1990s found a limited number of local sawmills (14 

private and 2 Commonwealth sawmills in Puerto Rico, 

11 small private sawmills in the USVI) that produced an 

estimated total annual production of 122,000 board feet of 

milled lumber (about 10,176 ft3

) in Puerto Rico (Kicliter 

1997) and about 45,000 board feet (about 3,750 ft3) in the 

USVI (Pierce and Hultgren 1997). These sawmills were 

found to be operating significantly below their productive 

capacity owing to a highly irregular wood supply (despite 

extensive forest resources) that was attributed to a lack 

of interest and capacity in forest management by forest 

owners (Kicliter 1997, Pierce and Hultgren 1997). Even 

fewer sawmills are operating in the Caribbean today 

(Brandeis et al. 2007). 

In Hawaii, native and natural forests are harvested for 

timber and nontimber products. In 2000, the total value 

of wood products harvested from Hawaii’s forests was 

estimated at $30.7 million (Yanagida et al. 2004). In 

addition to the harvest of wood products for Hawaii’s 

small commercial timber industry, there is an established 

craftwood industry developed by local artisans that 

produce a variety of arts and crafts from native wood 

species, most notably Acacia koa, as well as other native 

and nonnative species. Koa is highly regarded by artisans 

for its ecological, cultural, and economic values. Although 

there was no monitoring of or data on wood products 

harvests from natural and native forests at the time of 

this report, some suggest that commercial and artisanal 

harvests of native koa (Acacia koa), ohia (Metrosideros 

spp.), sandalwood (Santalum spp.), and hapuu tree ferns 

(Cibotium spp.) (all of which are found in natural forests) 

“are approaching the limits of available resources,” largely 

because the remaining stock of these species is found 

mostly on state or federally owned land or in areas zoned 

for conservation and off-limits to timber harvesting (State 

of Hawaii 2010). Conversely, inventory data from planted 

forests available for wood production indicate that most of 

Hawaii’s forest plantations are overmature or undermanaged, leading some to suggest that increased management 

and harvest is necessary for increasing their productivity, 

at least from the perspective of maximum timber production (Forest Industry Development Research 2006, State 

of Hawaii 2010). 

In the U.S.-affiliated Pacific islands, wood products from 

natural and planted forests are harvested mostly on an 

informal basis, but there are no associated monitoring 

activities or available data on harvest levels. Wood 

products are harvested domestically for housing and 

other building materials, as well as for canoes, furniture, 

handicrafts, and other wood-based products. Additionally, 

mangrove forests and other natural and planted forests 

provide an important source of fuelwood for many island 

communities. The general assumption across these islands 

is that most harvests occur far below forest growth rates; 

however, anecdotal evidence suggests that some island 

species and forests are not sustainably managed. For 

example, the State Forest Assessments for the FSM and 

Palau express concerns that demand for timber of some 

species may be exceeding growth rates and note the lack 

of important information on the levels at which forests 

can be sustainably harvested for wood products (FSM 

2010, Republic of Palau 2010). In particular, fuelwood 

harvests in the mangrove forests of Kosrae and Chuuk 

appear to be unsustainable, as do harvests of relatively 

rare large timber trees in the upland forests of Yap, where 

new sawmill establishment is on the rise despite a lack of 

information on sustainable timber supplies or regulations 

for commercial harvesting and processing (FSM 2010).

Indicator 2.14

Harvest of Nonwood Products

Nonwood forest products are important to communities 

and cultures throughout the islands. They represent 

nutritional, artisanal, recreational, cultural, and spiritual 

resources, perhaps most significantly in American Samoa, 

Micronesia, and Palau, where forests are heavily relied 

upon for subsistence. Yet, information on the growth 

and use of nonwood forest products is not systematically 

collected or analyzed in any jurisdiction, therefore it 

is impossible to determine if these resources will be 

available at present rates for future generations.

In the Caribbean, forests are important sources of nonwood forest products to many segments of the population, 

including artisans, fishermen, shrimpers, and everyday 

citizens (Francis 2004, Robinson 1997). Harvested 

products range from medicinal plants, arts and crafts 

materials, and food and forage to floral and horticultural 

products, resins, and oils. Forests provide important 

medicinal resources for the treatment and prevention 

of illnesses and other medical issues for many Puerto 

Ricans and Virgin Islanders (Martinez and Martinez 

2002, Palada et al. 2005, Taylor 2005). Forest streams and 

other water bodies in Puerto Rico are highly valued and 

used by artisanal shrimpers and fishermen (Hein et al. 

2008). Harvesting and hunting of other forest-associated 

fauna are rare in the Caribbean, with the exception of 

hunting and other means of population control of invasive, 

nonnative species such as feral pigs and goats (DFW 2001, 

DiFiore 2001, Fox 2008). 
II–32 Assessing Forest Sustainability in the Tropical Forests of the United States

Similarly, Hawaiian forests are important sources of nonwood forest products. They are used for the collection of 

ferns, honey, other food products, forage, arts and crafts 

materials, and more (State of Hawaii 2010). In particular, 

hunting nonnative mammals and birds is a popular activity for many local residents and some tourists. Hunting of 

some species, such as feral pigs, serve multiple purposes, 

including recreation and population control, particularly 

for feral animals that have significant and widespread 

effects on forest structure and composition. 

There are about 916,000 ac of public hunting areas in 

Hawaii, which in 2010 provided nearly 9,200 hunter trips 

for game birds and 30,500 trips for game mammals, 

totaling 39,370 trips (or hunter days) (State of Hawaii 

2011). In addition, the number of hunter trips and animal 

takes are increasing. Hawaii’s state game management 

plan (2012–2016) provides opportunities for recreational 

hunting of 15 species of nonnative game birds and six 

species of nonnative game mammals, and aims to direct 

hunting toward less ecologically sensitive areas, while at 

the same time providing structured hunter access to more 

remote/pristine sites. 

Forests provide resources for food, shelter, tools, utensils, 

and transportation throughout the U.S.-affiliated Pacific 

(Balick et al. 2009, FSM 2010, Republic of Palau 2010). 

They are commonly used for a variety of medicinal, 

cultural, and other practices and are considered essential 

for preserving local livelihoods and traditions (see, for 

example, Kitalong et al. 2011). However, there are no data 

on their removal or harvest levels. Native and nonnative 

plant species are harvested for handicrafts, clothing, oils, 

medicine, fishing gear, and other products that are integral 

to traditional life on many of the islands. For example, 

in Micronesia, it is estimated that as much as 60 percent 

of the population depends on the forest for subsistence, 

including timber and nontimber resources for food 

supplies, wood-fuel, medicinal needs, and other nontimber 

products and materials (FSM 2010). These resources are 

“crucial to sustaining the country’s rich ethnobiological 

traditions while improving Micronesians’ quality of life” 

(FSM 2010). Pacific island forests also provide habitat 

for game animals such as feral pigs. Hunting, preparing, 

and sharing domesticated and feral pigs are important 

activities in island culture. Yet some hunting techniques, 

including the use of fire, negatively affect native forest 

vegetation, particularly in Guam and Palau. These 

practices compound the effects of feral pigs and other 

ruminants on forests, such as the “spread of invasive 

plants, damage to understory vegetation, and destruction 

of riparian areas by their feeding and wallowing behavior” 

(Republic of Palau 2010). 

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Kitalong, A.H.; Balick, M.J.; Rehuher, F.; Besebes, 

M.; Hanser, S.; Soaladaob, K.; Ngirchobong, 

G.; Wasisang, F.; Law, W.; Lee, R.; Tadeo V.R.; 

Kitalong, C.; Kitalong, C.U. 2011. Plants, people 

and culture in the villages of Oikull and Ibobang, 

Republic of Palau. In: Liston, J.; Clark, G.; Alexander, 

D., eds. Pacific island heritage: archeology, identity & 

community. Canberra, Australia: ANU E Press: 63–84.

Little, E.L, Jr.; Skolmen, R.G. 1989. Common forest 

trees of Hawaii: native and introduced. Agric. Handb. 

679. Washington, DC: U.S. Department of Agriculture, 

Forest Service. 321 p.

Martinez, T.T.; Martinez, R.R. 2002. Medicinal 

herbs from the Caribbean National Forest (El 

Yunque), Puerto Rico. Proceedings of the Western 

Pharmacology Society. 45: 20–22. 

Matsuwaki, D.H. 2015. Plantation acreage by island and 

land ownership type. Unpublished report. On file with: 

Hawaii Department of Lands and Natural Resources, 

Division of Forestry and Wildlife, 1151 Punchbowl St., 

Honolulu, HI 96813.

Palada, M.C.; Mitchell, J.M.; Becker, B.N.; Nair, 

P.K.R. 2005. The integration of medicinal plants 

and culinary herbs in agroforestry systems for the 

Caribbean: a study in the U.S. Virgin Islands. Acta 

Horticultural. 676: 147–153.

Pierce, S.; Hultgren, P., eds. 1997. Forest products of 

the U.S. Virgin Islands: an overview of trends in forest 

products use. St. Croix, U.S. Virgin Islands: Virgin 

Islands Resource Conservation and Development 

Council. 31 p.

Republic of Palau. 2010. The Republic of Palau 

statewide assessment of forest resources and resource 

strategy—a comprehensive analysis of forestrelated conditions, trends, threats and opportunities. 

Ngerulmud, Palau: Ministry of Natural Resources, 

Environment & Tourism, Bureau of Agriculture, 

Forestry Section. 106 p.

Robinson, K. 1997. Where dwarfs reign: a tropical rain 

forest in Puerto Rico. San Juan, PR: University of 

Puerto Rico Press. 241 p.

State of Hawaii. 2010. Hawaii statewide assessment of 

forest conditions and trends: 2010—an assessment 

of the state of our ‘Aina. Honolulu, HI: Hawaii 

Department of Land and Natural Resources, Division 

of Forestry and Wildlife. 271 p. + appendices. https://

dlnr.hawaii.gov/forestry/files/2013/09/SWARS-EntireAssessment-and-Strategy.pdf. (February 2017).

State of Hawaii. 2011. Pittman-Robertson wildlife 

restoration program, game management program 

FY17– FY21. Program narrative W-22-G, segments 

17-21. Honolulu, HI: Hawaii Department of Land and 

Natural Resources, Division of Forestry and Wildlife. 

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PR-FY17-21FINAL05_03_2016web.pdf. (16 February 

2017).

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a guide to understanding and using herbal medicinals. 

New York: Square One Publishers. 528 p.

Territory of Guam. 2010. Guam statewide forest 

resource assessment and resource strategy 2010–2015. 

Mangilao, Guam: Department of Agriculture, Forestry 

& Soil Resources Division. 142 p. + appendices. http://

www.thewflc.org/islandforestry/guam.pdf. (September 

2016). 

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Virgin Islands. Turrialba. 38: 308–317.

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Lowland ‘ōhi’a (Metrosideros polymorpha) forest in Puna, Hawaii, before (2005) and after (2015) rapid 

ohia death (Ceratocystis fimbriata) infection. 

J.B. Friday J.B. Friday
Assessing Forest Sustainability in the Tropical Forests of the United States II–37

Kathleen S. Friday

Introduction

The health of an ecosystem depends on the proper functioning and interactions of that ecosystem’s characteristic 

species and natural processes. The native species of a 

given ecosystem have evolved or persisted within certain 

environmental conditions; disturbance events and stresses 

(such as storms and native insects and disease agents) 

may be characteristic of that ecosystem, with cyclical 

effects as the ecosystem naturally recovers. Disturbances 

and stresses resulting from human activities include 

the introduction of nonnative species, climate change 

and associated sea-level rise, and land clearance. Forest 

ecosystems may also be formed of nonnative species, by 

husbandry (agroforests and plantations) or by colonization 

by nonnative species so pervasive that to varying degrees 

they form stable, “novel” (Hobbs et al. 2006) forest 

ecosystems in conjunction with native species. The health 

of such ecosystems is defined by the functioning of their 

biological and physical processes and their ecosystem 

services, which will depend in large part on interactions 

between the system’s various species, both native and 

introduced. 

A key question is whether disturbances are so great or 

frequent that forest composition, structure, and function 

are degraded temporarily or permanently. Disturbances 

and stresses may interact, compounding their impacts. For 

example, drought may combine with anthropogenic wildfire and native grasses, or with natural fire and nonnative 

grasses. In addition, the decline or absence of certain 

agents and processes that once were part of forest ecosystems may also have an impact on forest health and vitality. 

For example, reduced numbers or even extinction of 

pollinators and seed dispersal agents, especially birds and 

bats in the islands, may directly affect species dependent 

upon their services; this in turn may affect forest ecosystem structure and function. (See indicators 1.04, 1.05, and 

1.06 in Criterion 1 for a discussion of biodiversity in the 

islands).

To an island landowner or citizen, a “healthy forest” may 

mean a forest of timber or a food species, productive 

because it has few insect or diseases. The broad definition 

of forest health explained above may seem contradictory 

to this benefits-based approach, because a native forest 

Criterion 3

Assessing Forest Sustainability in the Tropical Forests of the United States

Maintenance of the Ecosystem Health and Vitality

ecosystem deemed healthy with respect to biodiversity 

may include native insects and diseases. Conversely, a 

nonnative plantation, deemed healthy with respect to productivity, may be detrimental to the health of the forested 

landscape if it is a seed source for a species that invades 

and transforms native ecosystems nearby. Some (but 

not all) nonnative species, by their introduction, cause 

or are likely to cause economic or environmental harm 

or harm to human health, and, as a result, are designated 

as invasive species (Executive Order No. 13112). Some 

nonnative species may naturalize (without meeting this 

definition of invasivity) and form integral components 

of a “healthy” novel ecosystem. Perspectives regarding 

the role of nonnative species in forest ecosystems often 

differ (Lugo 2015), but there are also important areas of 

agreement. Many island forests have been so affected by 

invasive pests or fire that ecologists and citizens alike recognize “unhealthy forests” or forests that have degraded 

until they are no longer even forests, but grasslands. There 

are also “novel” forests and “traditional” agroforests that 

are dominated by nonnative species and valued as healthy 

ecosystems or forms of sustainable agriculture.

Criterion Summary

Abiotic stresses (fire, storms, sea-level change) are 

strongly influenced by climate, which differs by region as 

well as locally on islands with strong orographic rainfall 

patterns. Fire is of great concern in the western Pacific, 

where it occurs in anthropogenic grasslands and along 

forest edges, and in dry areas of Hawaii and of southern 

and western Puerto Rico. Volcanic eruptions affect 

several islands. Storms differ in frequency (the Marianas 

are in the typhoon belt) but may profoundly affect any 

island. Tsunami effects during the 2003–2010 period were 

limited to American Samoa. Land clearance differs with 

each island’s circumstances. In the Pacific, the effects of 

climate change may still be largely within the range of 

natural variation for several decades. Climate-induced 

sea-level rise is already in evidence, and the atoll island 

forests in the Pacific will be increasingly overwashed and 

their people likely displaced; the Republic of the Marshall 

Islands has no high island refuge.

Islands and regions differ in the degree to which their 

native ecosystems have been affected by introduced species, especially those species deemed invasive. Hawaiian 
II–38 Assessing Forest Sustainability in the Tropical Forests of the United States

forests are highly susceptible to species invasions and 

alteration; their previously isolated native species are not 

adapted to high levels of competition and herbivory. In 

addition, much of Hawaii’s forest has been historically 

cleared or grazed, then left open to nonnative plants. 

Most islands of the Marianas have been heavily affected, 

owing to centuries of interaction with America and Asia 

(with attendant species introductions) and disturbance 

from intensive bombing during World War II. Although 

introduced plant species are present and widespread in 

the U.S. Virgin Islands (USVI) and Puerto Rico, their 

domination of plant communities on those islands is not 

perceived as a serious concern except where introduced 

grasses have replaced forests after repeated humancaused fires. American Samoa and the Caroline Islands 

are intermediate in terms of the effects of introduced 

species; widespread nonnative agroforests are the result 

of husbandry (planting) rather than invasion, and native 

ecosystems persist but are subject to effects from various 

nonnative species. Succession from monospecific stands 

of invasive tree species to novel ecosystems including a 

substantial native component has been documented in the 

Caribbean (Lugo 2004); by contrast, the restoration of 

native forest ecosystems in Hawaii has been documented 

only with intensive management.

The Indicators

Criterion 3 of the Montréal Process Criteria and Indicators 

(MP C&I) focuses on biotic and abiotic processes and 

agents; metrics for both indicators are the area and percentage of forest affected beyond “reference conditions.” 

As in the National Report on Sustainable Forests (USDA 

FS 2011), this report presents data for 2003–2010 where 

available for comparison with reference conditions prior 

to 2003. The national report, where relevant and possible, 

compares present-day forests with conditions at the time 

of European colonization of the continental United States 

(circa 1630). Especially for the Pacific, where human 

settlement and European contact occurred much later, 

reference conditions “before human settlement” (that is, 

native ecosystems) are relevant to this criterion insofar as 

that event on each island is marked by the introduction of 

nonnative species and anthropogenic fire. 

The area and percentage of forest affected by biotic 

agents are not available as single metrics for the islands. 

Other than Hawaii (Conry et al. 2008, Gon et al. 2006), 

no jurisdiction has mapped overall “native” versus 

“nonnative” vegetation; mapped vegetation types such as 

“secondary vegetation” and “upland forest” are ambiguous with respect to the origins of their flora. The U.S. 

Forest Service’s Forest Inventory and Analysis (FIA) 

protocols are not designed to detect all occurrences of 

nonnative species. No jurisdiction has comprehensively 

or consistently mapped forests affected by insects or 

disease. Mapping typically is used to track the spread or 

impacts of pests of particular concern, rather than being 

more inclusive of all agents and looking at forest ecosystem health. Likewise, the extent, population density, 

and spread of various introduced vertebrates are studied 

for the purposes of species-based control, not to look at 

long-term ecosystem impacts across multiple taxa. The 

number of invasive or nonnative species found in the 

islands is a readily available metric that shows both the 

trend of introductions and the high number of documented 

invasive species in the islands. 

Our discussion of “abiotic” processes includes land 

clearance. A pattern of small-scale agricultural and 

agroforestry clearing and disturbance within generally 

forested areas is a characteristic form of disturbance in 

tropical islands. Clearance and revegetation may be part of 

a traditional, productive forest management system that is 

sustainable even though different in species composition 

than undisturbed forest. However, if the pace and scale of 

clearings accelerates, soil resources and species richness 

may be degraded, and the system may become unsustainable. (By contrast, large-scale permanent conversion 

of land use from forest to urban or agricultural uses is 

covered under Indicator 1.01, area of forests.)

For reference, the MP C&I indicators for Criterion 3 

are as follows:

• 3.15: Area and percent of forest affected by biotic 

processes and agents (e.g., insects, disease, invasive 

alien species) beyond reference condition. 

• 3.16: Area and percent of forest affected by abiotic 

agents (e.g., fire, storm, land clearance) beyond reference conditions.

Indicator 3.15

Area and Percent of Forest 

Affected by Biotic Processes 

and Agents (e.g., Insects, 

Disease, Invasive Alien Species) 

Beyond Reference Condition

Alien (nonnative or “exotic”) species, including insects 

and diseases, have been introduced in large numbers to 

the islands, accidentally or deliberately, by indigenous 

people and modern commercial activity. Of these introductions, some are valuable or harmless, while others are 
Assessing Forest Sustainability in the Tropical Forests of the United States II–39

predicted or observed to be invasive. The Hawaii Weed 

Risk Assessment predicts whether a given species will 

cause economic or environmental harm or harm to human 

health in any Hawaii ecosystem, via a scoring system 

that has been validated by field observations of nonnative 

species that were introduced more than 40 years ago. In 

Hawaii, “environmental harm” is considered to include 

“substantial effects on native ecosystems;” however, 

a nonnative species that naturalizes is not necessarily 

labeled “invasive” (Daehler et al. 2004). Similarly, Kairo 

et al. (2003) distinguished between nonnative species in 

the Caribbean that were merely naturalized (established in 

the wild) versus those considered to be invasive (reported 

to be spreading, regarded as a threat to a native species or 

ecosystem, or causing negative socio-economic impacts). 

In the extreme case among the islands, Hawaii has had 

about 10,000 plant species introduced, of which about 

1,150 have escaped cultivation and 176 are listed in the 

Global Invasive Species Database (table C3-1), contributing to extensive loss of native forest, as discussed below.

Insects (Native and Nonnative)

FIA data do not indicate widespread insect damage in 

most tropical island forests. In the Pacific west of Hawaii, 

fewer than 5 percent of trees are dead for any reason. The 

data give no indication that insects are a major cause of 

the mortality that has occurred. For all Caribbean and 

Pacific islands with FIA data, the proportion of total live 

trees damaged for any reason ranges up to 37 percent. 

Considering live trees with any form of damage, and 

attributing that damage to insects vs. other factors, insects 

are primary damage agents in 2 to 16 percent of cases 

of damage (depending upon the island), and therefore on 

less than 5 percent of all live trees on most islands. One 

exception is the Republic of the Marshall Islands, where 

18.5 percent of trees were damaged by insects, all by 

foliar damage to Scaevola taccada. Hawaii may also be 

an exception, but comparable FIA data has not yet been 

published for Hawaii.

Newly introduced insects do often have severe impacts on 

certain plant species, including rare or endemic species 

or valued agroforest species. Guam’s native cycad (Cycas 

micronesica) is declining rapidly from infestation of the 

cycad aulacaspis scale (Aulacaspis yasumatsui) and other 

native and introduced pests. Coconut rhinocerous beetle 

(Oryctes rhinoceros) was first detected in Guam in 2007 

and the eradication zone increased to 3,335 ac in 2009; 

growth of beetle populations has been slowed, and its 

spread has been limited by sanitation and trapping. (Neither the scale nor beetle had affected Guam at the time of 

the 2002 FIA survey.) The Erythrina gall wasp, Quadristichus erythrinae, first found in Hawaii in 2005, has 

killed nearly all nonnative Erythrina variegata trees on 

the islands to which it has spread. Mortality of Hawaii’s 

endemic E. sandwicensis stands has been as high as 50 

percent in some stands. Biocontrol has resulted in recovery and resumed flowering. Biocontrol of the Seychelles 

scale insect (Icerya seychellarum) in the Manu’a islands 

of American Samoa has enabled significant recovery of 

breadfruit (Artocarpus altilis) trees between 1999 (when 

damage was “serious”) and 2010, when a survey found 

that scales had been suppressed to “very low” levels. 

Thirteen species of cacti in the subtropical dry forests of 

Puerto Rico are threatened by Harrisia cactus mealybug, 

Hypogeococcus pungens, a native of South America. 

In the Pacific, the effects of these and other insects are 

reported by Neville (2014) and annually in Forest Health 

Highlights (described in chapter 2).

Some insects do not affect plants directly but disrupt the 

forested ecosystem and forest economics. Africanized 

Table C3-1. Number of documented invasive terrestrial species in the U.S. tropical islands

Taxonomic group

Number of invasive species per jurisdiction

Puerto 

Rico

U.S. Virgin 

Islands Hawaii

American 

Samoa

Marshall 

Islands FSM CNMI Guam Palau

Mammals 7 7 15 5 6 7 10 8 6

Birds 6 1 10 2 3 1 1 4 1

Amphibians 3 3 5 1 1 1 1 3 1

Reptiles 4 0 8 2 2 4 5 5 2

Insects, arachnids, 

centipedes/millipedes

14 12 28 8 6 6 9 12 8

Plants 57 25 176 41 45 62 52 67 52

Snails 0 0 5 2 1 1 2 3 2

 Total 91 48 247 61 64 82 80 102 72

FSM = Federated States of Micronesia; CNMI = Commonwealth of the Northern Mariana Islands.

Source: Global Invasive Species Database 2011.
II–40 Assessing Forest Sustainability in the Tropical Forests of the United States

bees threaten the nesting success of the Puerto Rican 

parrot (Amazona vittata). Little fire ants (Wasmannia 

auropuntata) hinder forest and agroforest management 

activities by stinging people; other invasive ants have 

facilitated the rapid decline of stands of Pisonia grandis

trees on some Pacific atolls by protecting damaging scale 

insects from natural enemies (Krushelnycky et al. 2005).

Disease (Native and Nonnative)

FIA data (Brandeis and Oswalt 2007; Brandeis et al. 

2007; Donnegan et al. 2004a, 2004b, 2007, 2011a, 2011b) 

indicate relatively little overall tree damage caused by 

diseases in tropical island forests, though it must be noted 

that FIA methods and reporting differ between the Caribbean and the Pacific, and FIA data has not been published 

for Hawaii. In the Pacific jurisdictions west of Hawaii, the 

percentage of live trees with any form of damage ranged 

from 11 to 37 percent, but only 2 to 19 percent of that 

damage is primarily attributed to disease; the total percentage of live trees with damage primarily attributed to 

disease was at a maximum 2.5 percent In Puerto Rico and 

the USVI, the most common disease was fungal infection 

and decay (63 percent of all damaged trees); this indicates 

that fungal infection is a primary damage agent on 8.6 

percent of all live trees in Puerto Rico and 2.4 percent in 

the USVI. 

Despite these low overall figures, diseases are significant 

and of concern for agroforest crop species, e.g., citrus canker in Kosrae, citrus greening (Huanglongbing) in Puerto 

Rico and the USVI, and Phellinus noxious on breadfruit 

and other species in the Pacific.

In Hawaii, two widespread diseases were of particular 

concern during 2003–2010. Koa wilt (Fusarium oxysporum, affecting Acacia koa) is present on all islands 

at elevations up to 7,000 ft. Widescale dieback has not 

been observed in natural forests, but high incidence and 

mortality rates are found in koa plantations below 3,000 

ft elevation. An invasive rust (Puccinia psidii) was first 

detected in 2005 and is present on all major islands up 

to 4,500 ft, attacking a variety of native and introduced 

Myrtaceae. The geographic range of the rust has been 

mapped, but acres and percentage of forest affected have 

not been quantified. The greater reason for concern is the 

potential for the rust to adapt or for more virulent strains 

to be introduced, affecting ohia (Metrosideros polymorpha), Hawaii’s most widespread and ecologically important native tree. Finally, even though this report focuses on 

2003–2010, a disease just detected in 2010 (Ceratocystis 

fimbriata wilt of ohia) must be noted because of its rapid 

spread to 34,000 ac (DLNR 2016) and serious threat of 

catastrophic loss of ohia forests statewide. It is not yet 

known whether this is a result of an introduction of an 

exotic strain of the fungus or whether this constitutes a 

new host of an existing strain (Keith et al. 2015).

Invasive Alien Species—Plants

Hawaii’s native ecosystems, which evolved in relative 

isolation, have been radically altered by invasive plants. 

Figure C1-4 (see Criterion 1 above) shows that 14 percent 

of Hawaii was transformed into alien (nonnative) forest by 

2003 (little of which consists of plantations); an additional 

25 percent was transformed into alien grasslands and 

shrublands. In some places, this shift resulted from direct 

invasion by plants into native forest, such as nonnative 

Albizia (Falcataria moluccana) establishing itself and 

growing above the relatively open canopy characteristic of 

native Ohia (Metrosideros polymorpha) on young substrates. In other cases, nonnative plants colonize disturbed 

areas instead of native plants after land use conversion, 

grazing, or fire (in Hawaii, fire itself is sustained primarily by nonnative grasses). Of the remaining 21 percent 

mapped as native forest, much is affected by nonnative 

plant species to some degree and may be in transition to 

nonnative forest types, as alien shrubs such as strawberry 

guava (Psidium cattleianum) occupy the growing space 

and hinder native forest regeneration. 

Also now dominated by “novel ecosystems” are Guam, 

Saipan, and Tinian of the Mariana Islands. Many invasive 

and other nonnative plants have exploited openings in the 

forest created through disturbance, especially clearing 

for and subsequent abandonment of intensive agriculture 

prior to World War II; World War II bombardment; and 

disturbance for urban development. A prime example is 

Leucaena leucocephala, widely believed to have been 

direct-seeded in the Mariana Islands after World War II. 

On Saipan and Tinian, only about 5 percent of the land 

area is still native forest, and almost two-thirds is Leucaena shrubland and “mixed introduced forest” (Falanruw 

et al. 1989). Guam lacks data, but its self-assessment is 

that, despite relatively constant forest cover since World 

War II, the condition of the forest has declined in response 

to continuous abiotic disturbance pressures and the 

number of nonnative species being introduced.

Other islands have more intact native forest, with varying 

susceptibility to invasion. Falcataria became an emergent 

(upper canopy tree) over about 12,000 ac in American 

Samoa (35 percent of Tutuila) before control efforts 

beginning in 2001 reclaimed nearly 2,000 ac of native 

forest. A key question is whether invasive species in the 

canopy provide a favorable environment for native species 
Assessing Forest Sustainability in the Tropical Forests of the United States II–41

regeneration. Abelleira Martínez et al. (2010) indicate 

that the most common tree in Puerto Rico, the African 

tulip tree (Spathodea campanulata Beauv), an introduced 

species, speeds restoration of forest structure and native 

tree regeneration on abandoned agricultural and grazing 

lands. Introduced plant species in Puerto Rico include 

16 invasive tree species identified by the Global Invasive 

Species Database (2011) out of a total of 123 introduced 

tree species documented by Francis et al. (2000). Many 

of these have extended their range in the wild, yet none 

have been documented to replace native tree species. The 

database reports 11 invasive plants in the USVI; although 

widespread, they do not dominate most plant communities (Oswalt et al. 2006). Leucaena is one tree listed as 

invasive in the database that does persist and dominate 

some plant communities in the Caribbean, with benefits 

and risks as a species used in management (Wolfe and 

Van Bloem 2012).

Invasive Vertebrates

The introduction of ungulates or carnivores to isolated 

islands typically has a profound effect on native island 

ecosystems that evolved in their absence. Ecosystem 

structure, function, and species composition may be 

fundamentally changed as: 

• Grazing animals (goats, sheep, mouflon, deer, and feral 

cattle and horses) browse vegetation, hinder regeneration, and over time may convert forests to rangelands, 

sometimes occupied by fire-prone grasses.

• Predators (snakes, rats, feral cats, monkeys, and mongooses) prey on native bird eggs and nestlings, with 

attendant secondary effects on pollination and dispersal. 

• Rats, iguanas (López-Torres et al. 2011), and other animals consume seeds, fruits, and flowers of many native 

plant species.

• Trampling and rooting animals (especially hogs) disturb 

and scarify soil, leading to erosion or establishment 

of invasive plants. In general, forests on all but some 

of the smallest or most isolated islands are affected 

throughout most of their extent by at least one invasive 

vertebrate. The entirety of Guam (except a few very 

small offshore islands) is profoundly affected by the 

brown tree snake (Boiga irregularis), which extirpates 

forest birds; rats are found in abundance throughout 

most of Hawaii’s forests; feral pigs are abundant in 

many forested areas of American Samoa; monkeys 

harm threatened and endangered species in Puerto Rico 

and cause damage to agriculture and orchards as well 

(Engeman et al. 2010); and the mongoose is widespread 

in a wide variety of habitats in Puerto Rico, and so 

forth. 

Indicator 3.16

Area and Percent of Forest Affected 

by Abiotic Agents (e.g., Fire, Storm, 

Land Clearance) Beyond Reference 

Conditions

Fire

Fire occurs naturally on islands with active volcanoes, but 

fire from lightning strikes is rare, and nearly all fire (apart 

from active lava flows) is anthropogenic, so its effects are 

outside of the natural disturbance regime. Repeated fire 

leads to exposure and erosion of soil and changes in forest 

structure and species composition. 

Since human settlement, fire has greatly affected islands 

with dry or mesic forests or dry seasons. The current, 

most notable trend is in Hawaii and Puerto Rico, where 

the leeward (dry) sides of the islands have experienced an 

increase in the number and severity of wildfires owing to 

a combination of increased ignition sources by humans 

and the spread of nonnative fire-adapted grasses, shrubs, 

and trees, of which fountain grass (Pennisetum setaceum) 

is the best example. The year 2007 was one of the 10 

hottest years on record by that time, which could account 

for increased fire activity in Puerto Rico and the USVI 

that year.

Guam and the CNMI have a long history of arson by 

hunters, and Palau a history of agricultural burning and 

current-day arson. However, for these islands, consistent 

published data are unavailable for long-term trends in 

fire frequency and effects on forests. Grassland fires 

degrade forest fragments and forest edges and stop forest 

regrowth. Urban development of grasslands can increase 

ignitions or reduce fuels. Despite the common occurrence 

of fire in grasslands that neighbor forests, total forest 

cover in Guam has been relatively unchanged over the 

past 50 years.

Fire danger throughout Micronesia’s wetter islands is 

associated with drought during El Niño years, for which 

predictive capacity has improved. Early prediction of the 

severe 1997–1998 El Niño drought enabled public fire 

prevention education programs to actually reduce acres 

burned in Yap.

Volcanic Emissions

Lava inundation affects forests in Hawaii, and volcanic 

emissions affect forest health over wide areas. Since 

2008, increased emissions, including sulfur dioxide, and 
II–42 Assessing Forest Sustainability in the Tropical Forests of the United States

volcanic fog (vog) and acid rain from Kilauea Volcano 

in Hawaii, have been sufficient to cause acute injury to 

plants near Kilauea and chronic injury at greater distances. Ash from the Soufrière Hills volcano on Montserrat fell on Puerto Rican forests in 2001, and ash from 

Anatahan fell on other Mariana Islands in 2003, affecting 

forest nutrient fluxes.

Storms

Hurricanes (called typhoons west of the international 

dateline) and tropical storms, with associated salt spray 

and ocean surges, are a natural disturbance in island 

forest ecosystems, though occurring at different intervals 

in different regions. The Mariana Islands are affected by 

multiple typhoons annually, and the USVI once every 15 

years or so. Major recent hurricanes in Puerto Rico and 

the USVI include Georges in 1998, Andrew in 1992, and 

Hugo in 1989. Yap was hit by Sudal in 2004, its strongest 

typhoon in 50 years, causing extensive forest defoliation 

and mortality. Kauai was struck by the eye of a category-four hurricane, Iniki, in 1992, the strongest to make 

landfall in Hawaii’s recorded history; forests there still 

have persistent effects from species invasions into forests 

damaged by the storm. No major typhoon has struck 

Pohnpei or Kosrae, in the central Pacific, for over 100 

years. Forest plant species and types have evolved within 

these disturbance regimes and demonstrate considerable 

resilience to varying levels of recurring effects from 

storms and hurricanes. In Puerto Rico, the degree of 

forest damage and associated capacity for forest recovery 

is also strongly dependent on the history of land use 

and hurricane damage, such that where there are greater 

anthropogenic impacts on the forest or surrounding areas, 

capacity for recovery decreases (Boose et al. 2004).

Heavy sustained rainstorms on the steep slopes and 

weathered soils of the high Caroline Islands (Kosrae, 

Chuuk, Pohnpei, Yap, and Palau) and Puerto Rico result 

in landslides, either related to slope disturbance from 

infrastructure construction or naturally occurring slumps. 

These landslides carry away upland forests and agroforests, leaving behind barren slopes; soil and debris are 

deposited on lower slopes and (on small islands) mangrove 

forests, producing sediments that can be washed into 

nearshore marine environments. Typhoon Chata’an thus 

affected hundreds of acres of forest on the small islands 

of Chuuk in 2002; scarps remain thinly vegetated today. 

Landslides have increased over the last decade in Palau 

(largely resulting from construction of 

the Compact Road).

Tsunami

American Samoa was struck by a large tsunami in 2009. 

Coastal forests were uprooted and experienced erosion; 

effects were more significant where coastal vegetation 

was already sparse.

Climate Change

Over the next century, climate change is expected to 

increase base sea levels and temperature steadily. 

Sea levels are highly variable in the western Pacific on a 

daily, seasonal, or decadal basis from storm surges, low 

pressure events, and currents. In western Micronesia, 

the rate of mean sea-level (MSL) rise was greater than 

the global rate between 1993 and 2010 (fig. C3-1). This 

was because of a multidecadal increase in the strength of 

the trade winds (La Niña-dominated conditions). These 

extraordinary rates of increase are not expected to persist 

over time, because sea levels in the north central and 

western Pacific fall under El Niño-dominated conditions 

(Leong et al. 2014). In the meantime, they provided a preview of anticipated high sea levels in the long-term future. 

The effects of these increased sea levels are amplified by 

storm surges, eroded coastal vegetation, and hindered 

restoration of coastal strand forests in the western Pacific. 

Changes in the extent of mangrove forests are expected 

as their seaward fringes are inundated and as mangroves 

colonize increasingly brackish estuaries; Gilman et al. 

(2007) predicted a 12-percent decrease in the extent of 

mangrove forests in the U.S.-affiliated Pacific islands 

by 2100. The superimposed effect of base sea-level rise 

will increase the frequency of high-sea-level events that 

pass given thresholds. For example, sea levels that breach 

coastal berms contaminate freshwater lenses and freshwater swamps behind the berms; this affects coastal and atoll 

agroforestry systems. When frequency exceeds recovery 

periods for such events, ecosystems and societies will be 

transformed, and atolls with narrow reef flats may become 

uninhabitable within decades rather than centuries 

(Storlazzi et al. 2015).

Storms, droughts, and prevailing sea level in the Pacific 

are driven by El Niño–Southern Oscillation (ENSO) 

cycles; it is not yet clear how climate change will affect 

ENSO cycles. The variable effects of ENSO on storms 

and rainfall are expected to overwhelm incremental 

climate change in the Pacific for several decades (Australian Bureau of Meteorology and CSIRO 2014). As a 

matter of perspective, major El Niño events more than a 

century ago are associated with unusual and devastating 
Assessing Forest Sustainability in the Tropical Forests of the United States II–43

Figure C3-1. Mean sea level rise from 1993 to 2010, ranging from an average of -0.4 inch/year (blue) to 

0.6 inch/year (red). Note: Sea-level rise is shown by the source as “mm/year.” Multiply 1 millimeter by 

0.0394 to find inches. Source: CNES/LEGOS/CLS 2015.

storms in eastern Micronesia at that time (Spennemann 

and Marschner 1994). Changes in global climate that 

result in increased temperature or decreased precipitation 

will affect freshwater stress, as modeled for islands by 

Karnauskas et al. (2016). Increased freshwater stress or 

periods of drought would likely increase fire frequency 

and its adverse effects. Changes in climate that result in 

warmer waters in the Atlantic Basin for longer periods 

of time will likely produce increases in the number and 

strength of hurricanes and storms that affect Puerto Rico. 

Mounting evidence indicates specific long-term effects 

on Hawaii’s climate and water: a rapid rise in air temperature, especially at higher elevations; decreased rainfall 

and streamflows in some areas; and moderate sea-level 

rise.

Land Clearance and Fill

Total forest cover in Puerto Rico has been steadily 

increasing through the early 2000s as the economy and 

land use have shifted away from agriculture, although 

urbanization is converting some forest land into other uses 

(Gould et al. 2007). Average forest age is young in fertile 

areas where agriculture persisted until recently giving 

way to forest. Overall, land use is a dynamic mosaic with 

increasingly fragmented forests (Franco et al. 1997). In 

the USVI, agricultural land uses have likewise given way 

to fragmented secondary forests, but urbanization has outweighed that trend and total forest cover is decreasing. In 

Hawaii, native forests are being cleared and fragmented in 

housing/agricultural subdivisions on the Big Island; native 

forests are also being degraded by cattle, but some former 

ranchlands are now being managed to restore native 

forest. On the other Pacific islands, data are inadequate 

to quantify net trends, but additional relevant dynamics 

include the construction of major roads providing access 

to lands for agroforestry and horticultural use (Palau); 

migration from outlying islands (Rota in the CNMI, and 

Tau in American Samoa); migration from atolls to central 

islands (Yap, Pohnpei); and programs to discourage 

upland forest clearing (Pohnpei). 

Forest loss from land clearing may be reversed when land 

is left fallow and forest regrows, as has been the case in 

Puerto Rico, parts of Palau, and other areas. Simple clearing of mangrove forests may or may not result in healthy 

regeneration, depending upon the substrate, hydrological 

regime, and other factors. Where mangrove forests are 

not only cleared but filled to above the high tide mark to 

create land for urban uses, the area will not revert to mangrove forest unless the fill is removed or washed away (or 

unless sea level rises above the fill). Mangrove forests are 

also affected by fill (causeways and roads) that impound 

or divert water; altered hydrological regimes may result in 

changes in species composition or conversion to freshwater wetland forest or nonforest estuaries. 
II–44 Assessing Forest Sustainability in the Tropical Forests of the United States

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Assessing Forest Sustainability in the Tropical Forests of the United States II–47

Criterion 4

Assessing Forest Sustainability in the Tropical Forests of the United States

Conservation and Maintenance of Soil and Water Resources

Kathleen A. McGinley

Introduction

Healthy and productive forests depend on the maintenance 

of soil and water resources. Forests also regulate these 

resources by moderating the flow of water, controlling 

erosion, and preventing flooding, landslides, and other 

potentially catastrophic events. If forest soils or waters 

become diminished or degraded, forest health and other 

environmental services also may decline. Well-managed 

forests can help protect important soil and water resources 

within the forest ecosystem and across the broader 

landscape.

Tropical soils range from deep, fertile soils occurring in 

volcanic regions or on nutrient-rich floodplains to shallow 

soils with limited nutrients that are prone to leaching and 

erosion. Forests rich in biomass and diversity are found 

across the range of tropical soil types. These forests 

exhibit high rates of decomposition and nutrient cycling 

associated with high temperatures and precipitation, 

levels of soil phosphorus and nitrogen, and numbers of 

soil insects and microorganisms. These factors accelerate 

the decay of plant and other organic materials, releasing 

nutrients that are quickly (re-)absorbed by living plants 

through the soil and surface or ground waters. Tropical 

forests occurring on rich and deep soils often are vulnerable to conversion to other uses, such as agriculture 

or livestock grazing. Forests occurring on shallow, poor, 

or unstable soils are susceptible to degradation through 

erosion or compaction if unsustainably logged or otherwise poorly used or managed.

Forests also are thought to play an important role in water 

resource quantity, quality, timing, and flows, especially 

on tropical islands where fresh water supplies often are 

limited and intricately linked from ridge to reef. These 

forests are essential for intercepting and storing water and 

nutrients; protecting soils, floodplains, and streambanks; 

cleaning and cooling air and water; reducing stormwater 

runoff; filtering pollutants from air and water; protecting 

municipal water supplies; reducing flooding; recharging 

groundwater aquifers; and providing critical habitat for 

aquatic wildlife. In riparian areas, forests adjacent to 

bodies of water buffer the movement of pollutants from 

upslope land use activities and support aquatic health 

through temperature regulation, additions to the food web, 

and provision of habitat structure. 

Overharvesting, poorly planned and unmaintained roads, 

unsustainable recreation, and other human activities 

can degrade soil and water resources and related forest 

functions. Conversely, the sustainable use and protection 

of forests can help protect these and other resources and 

services important to island dynamics and livelihoods. 

Best forest management practices, riparian zone protection, recreation management, and a wide range of additional measures are designed and implemented to protect 

forest water and soil resources. 

Criterion Summary

Forest soils and their quality and quantity range widely 

across the tropical islands. In much of the Caribbean and 

in parts of Hawaii and the Pacific, a significant portion of 

the total forest area has regenerated on lands previously 

used for agriculture or livestock grazing; these forests 

often occupy compacted, eroded, or otherwise degraded 

soils. As these secondary forests mature, they can contribute greatly to the recuperation, maintenance, and protection of valuable soil resources. Throughout the islands, 

and particularly in Hawaii and parts of the Pacific, forests 

are subject to degradation by feral ungulates, such as 

pigs and goats, which can have significant effects on soil 

resources through the uprooting of vegetation, exposure of 

soil and subsoil, and dispersal of nonnative plant species. 

Island forests also are essential to the supply, quantity, 

and quality of water resources within the watershed and 

in downstream communities. Human water consumption 

and other activities influence forest water resources and 

overall forest health throughout the islands. As with soil 

resources, the conversion of forest lands to other uses has 

significantly affected water availability and quality on 

most of the inhabited islands. In many cases, nonforest 

land uses, such as agriculture and livestock grazing, as 

well as industrial, urban, and tourism development, have 

led to overuse of existing water supplies; sedimentation of 

waterways and bodies, including reservoirs; and contamination of surface and ground waters. Moreover, without 

further conservation measures and implementation, the 

hydrological resources and services associated with island 

forests are likely to be further affected by feral ungulates, 
II–48 Assessing Forest Sustainability in the Tropical Forests of the United States

fire, nonnative invasive plant species, unsustainable water 

withdrawals and diversions, and climate change. 

Forests are protected to varying degrees for a range of 

values throughout the island jurisdictions, including the 

conservation of soil and water resources. However, very 

little of the protected forest area is designated solely 

for these purposes. In the Caribbean, the protection of 

riparian zones is mandated by law. In other areas, specific 

measures have been taken to protect and conserve the soil 

and water resources in critical watersheds (e.g., Hawaii, 

Federated States of Micronesia). 

Voluntary best management practices (BMPs) for forest 

use and conservation that include the protection of soil 

and water resources are available in Hawaii and Puerto 

Rico. Additionally, the U.S. Forest Service (USFS) Forest 

Stewardship Program, which is active in most jurisdictions, promotes long-term forest management that takes 

into account soil, water, wildlife, and other forest values 

through technical and financial assistance for forest 

planning and operations. Nevertheless, there is very limited systematic monitoring of forest use or conservation 

measures in any jurisdiction. 

The Indicators

The Montréal Process Criterion 4 contains five indicators 

related to the conservation and maintenance of forest 

soil and water (listed below). However, given the limited 

amount of available data for most of these indicators, we 

combined Indicators 18 and 20 for reporting purposes—

this strategy has been used in the National Report on Sustainable Forests as well (USDA FS 2011). The Montréal 

Process Criterion 4 indicators are as follows:

• 4.17: Area and percent of forest whose designation or 

land management focus is the protection of soil or water 

resources.

• 4.18: Proportion of forest management activities that 

meet best management practices or other relevant legislation to protect soil resources (combined with Indicator 

20 below).

• 4.19: Area and percent of forest land with significant 

soil degradation.

• 4.20: Proportion of forest management activities that 

meet best management practices, or other relevant 

legislation to protect water-related resources (combined 

with indicator 18 above).

• 4.21: Area and percent of water bodies, or stream 

length, in forest areas with significant change in physical, chemical, or biological properties from reference 

conditions.

Indicator 4.17

Forest Designated for the Protection 

of Soil or Water Resources

The formal protection of forests through governmental, 

nongovernmental, and private measures ranges widely 

across the islands (see Criterion 1). In addition to formal 

forest protection, traditional governance structures have 

resulted in widespread community forest management and 

protection, particularly in the Pacific islands. Although 

the protection of soil and water resources is among the 

primary management goals for most formally protected 

forest area, very little is solely designated for this purpose. 

In the Caribbean, riparian zones outside protected areas 

also must be protected by law. However, monitoring and 

enforcement are largely nonexistent. In Hawaii and parts 

of the Pacific, specific measures have been taken to protect and conserve the soil and water resources in critical 

upland watersheds. 

In the U.S. Virgin Islands (USVI), 14.7 percent of forests 

are formally protected under federal, private, and nongovernmental measures, and an additional 2.1 percent are 

formally managed or prohibited from conversion to other 

uses (Gould et al. 2013). Riparian zones are protected 

through the Virgin Islands Legal Code, which prohibits 

the cutting of vegetation within 30 ft of the center of 

a natural water course or body, or 25 ft from the edge, 

whichever is greater (VI Legal Code (Title 12, Chapter 

3, Section 123). Although there are few natural lakes or 

ponds and no permanent rivers in the USVI, intermittent 

or ephemeral rivers and streams that fill with water during 

times of high precipitation “play an important role in ... 

hydrological systems” (Heartsill-Scalley 2012). These 

riparian zones represent “one of the few remaining areas 

where canopy forest can be found in the USVI, [yet] 

despite legal protection, intermittent waterways continue 

to be degraded through clearing and paving, resulting 

in erosion and the rapid transportation of significant 

sediment loading in surface runoff directly to the marine 

environment” (Gardner 2008). 

In Puerto Rico, 11.6 percent of the forested area is 

formally protected through commonwealth, federal, 

nongovernmental, and private measures (Gould et al. 

2007). The islands’ major mountainous forest reserves 

(i.e., El Yunque National Forest; Carite, Toro Negro, 

Maricao, and Guilarte Commonwealth Forest Reserves) 

encompass the headwaters of the primary rivers and 

streams, which supply much of the water used for domestic, industrial, and agricultural uses (Weaver 2000). Three 

river segments within El Yunque National Forest, totaling 
Assessing Forest Sustainability in the Tropical Forests of the United States II–49

8.9 mi, have been federally designated as Wild, Scenic, 

and Recreational Rivers by the U.S. Congress (EYNF 

2008). These designations are intended to preserve rivers 

with outstanding natural, cultural, and recreational values, 

and their immediate environments, in a free-flowing 

condition for the benefit and enjoyment of present and 

future generations (CNFWSRA 2002). Maintaining 

water quality and natural flow characteristics is a primary 

management objective in designated river segments. El 

Yunque National Forest also encompasses the 10,000-ac 

El Toro Wilderness Area, which permits primitive trail 

construction and recreation for minimal use and primitive 

experience, but prohibits road construction or other development; motorized or mechanized use; timber harvesting; 

water development; manipulative (treatment vs. control) 

research; mineral activity; and high-use recreation and 

trails (EYNF 2008). 

Riparian zones in Puerto Rico are classified as public 

domain by the Commonwealth Government (PR Law No. 

136 3/6/1976). Buffers of at least 5 m (16.4 ft) must be 

conserved along waterways and around water bodies and 

should be protected and managed by the Commonwealth 

Department of Natural and Environmental Resources (PR 

Law No. 49). However, implementation of riparian buffer 

zone legislation is considered weak, and there is limited 

evidence of its enforcement (see, for example, Heartsill-Scaley and Aide 2003, Lugo et al. 2001).

In Hawaii, 13.1 percent of the total forest area is formally 

protected through federal, state, nongovernmental, and 

private initiatives, and another 29.7 percent is formally 

managed or is prohibited from conversion to other uses 

(Gon et al. 2006). In 1903, the State Forest Reserve 

System was established by the Territorial Government of 

Hawaii, with the active participation of private landowners. Today, these reserves cover 642,000 ac (16 percent 

of total land area) and are managed to provide a suite of 

public services, including “the protection and management of forested watersheds for the production of fresh 

water supply for public uses now and into the future” 

(State of Hawaii 2009).

Additional measures to protect watersheds, forests, 

and their soil and water resources include the Hawaii 

Watershed Protection Board, established by the Hawaii 

legislature in 2000 to identify critical watershed areas and 

determine sources of funding to implement watershed 

protection partnership projects (HAWP 2011). Watershed 

partnerships are voluntary alliances of public and private 

landowners committed to the protection of large areas 

of forested watersheds for enhanced water conservation, 

quality, and recharge and other ecosystem services and 

values. These partnerships engage in collaborative management activities such as invasive species control, habitat 

restoration, reforestation, and on-the-ground protection 

measures. By 2011, there were nine island-based watershed partnerships that involved more than 60 public and 

private partners on six islands working collaboratively to 

protect nearly 1.6 million ac of forested watershed lands 

(HAWP 2011). 

In the U.S.-affiliated Pacific jurisdictions, forest management and protection is on the rise, ranging from 9 to 23 

percent or more of total forest area per jurisdiction, as 

assessed under the Micronesia Challenge (PCS and TNC 

2011) (see Criterion 1). For example, in the Federated 

States of Micronesia (FSM), the state of Pohnpei has 

legally designated entire upper portions of the island’s 

major watersheds (14,524 ac) for the protection of soil 

and water resources (FSM 2010). However, a lack of local 

support and repeated forest clearing for high value cash 

crops in the area threatens the viability of certain watersheds in this reserve (FSM 2010). Also in Micronesia, the 

state of Kosrae created the Central Watershed Reserve 

(17,290 ac) for the protection of soil and water resources. 

The watershed covers about 67 percent of the total land 

area of Kosrae, much of which is currently under government control. Within the reserve, 4,940 ac are designated 

specifically for the protection and production of drinking 

water. This area encompasses the steepest land, most 

erodible soils, and uppermost elevations, and thus is 

intended to “protect much of the most sensitive parts of 

the watershed” (FSM 2010). 

Indicators 4.18 and 4.20

Forest Management Activities That 

Meet Best Management Practices or 

Other Relevant Legislation to Protect 

Soil and Water Resources

Voluntary BMPs for forest use and conservation have 

been developed by the government only in Puerto Rico 

and Hawaii. However, there are no known efforts to 

regularly collect data on BMP implementation or effects. 

Long-term forest management that takes into account 

soil, water, wildlife, and other forest values is a primary 

objective of protected areas in most jurisdictions, and 

also is promoted through the USFS Forest Stewardship 

Program, which provides technical and financial assistance to nonindustrial forest landowners through state 

forest agencies. 
II–50 Assessing Forest Sustainability in the Tropical Forests of the United States

In the Caribbean Islands, wood product harvests are not 

subject to mandatory BMPs for soil or water conservation, 

and only Puerto Rico promotes and prescribes BMPs for 

legally mandated riparian protection zones. However, 

the implementation and impacts of these BMPs are not 

monitored or measured. Voluntary BMPs are promoted, 

though not measured, through the Forest Stewardship 

Program, the Puerto Rico Commonwealth Auxiliary 

Forests, and other conservation programs. In 2009, there 

were 104 management plans for forest products and 

services covering 4,833 ac under the Forest Stewardship 

Program, and 73 auxiliary forest units covering 7,620 ac 

in Puerto Rico. In the USVI, 929 ac were enrolled in the 

Forest Stewardship Program.

Hawaii has a small, active forest products industry 

that is subject to BMP guidelines related to forest land 

management planning and operations for private forest 

landowners to assist them in their compliance with the 

federal Clean Water Act (CWA). Applicable sections of 

the CWA protect the nation’s waters from the uncontrolled 

discharge of pollutants (including sand, rock, and other 

fill materials) and prescribe a permitting process for any 

activity that may result in pollutant discharges (CFR CWA 

Section 404). The CWA exempts forestry and other activities from this permitting process, provided that operations 

are in compliance with 15 mandatory national-level BMPs 

that are implemented and oftentimes complemented by 

additional BMPs at the state level. 

Hawaii’s voluntary BMPs for Maintaining Water Quality 

address forest roads, preharvest planning, harvesting, 

silvicultural practices, streamside management zones, 

fencing, fire management, and reforestation (State of 

Hawaii 1996). Applications of these guidelines are 

voluntary and not enforceable, and there were no available 

quantitative data on their implementation or impacts at 

the time of this report. Notably, Hawaiian participants in 

the USFS Forest Stewardship Program “must commit and 

follow the practices described in their Forest Stewardship 

Management Plan, which are in compliance with the 

Department of Forestry and Wildlife Best Management 

Practices (BMPs) when preparing project sites for planting 

and harvesting any trees that are planted with program 

assistance” (State of Hawaii 2009). In 2009, 36 landowners with a total of 19,315 ac of forest land were enrolled 

in the Forest Stewardship Program in Hawaii (State of 

Hawaii 2009).

In the U.S.-affiliated Pacific jurisdictions, there are no 

known official BMPs for forest management, but largescale forest management operations also are essentially 

absent throughout much of the region. As in Hawaii 

and the Caribbean, the Forest Stewardship Program is 

implemented in the Pacific Island jurisdictions, where 

funds are used for extension and distribution of seedlings 

to encourage forest cover for watershed protection, as well 

as some landscape- and parcel-level planning. 

Indicator 4.19

Forest Land With Significant 

Soil Degradation

There is very little quantitative information on forest soil 

quality or degradation for any of the island jurisdictions. 

In general, a significant portion of the total forest area 

has regenerated on lands previously used for agriculture 

or livestock grazing. As a result, most secondary forests 

occur on compacted, eroded, and otherwise degraded 

soils, where they contribute greatly to the rehabilitation, 

maintenance, and protection of the islands’ soil resources.

The most common threats to forest soil quality across 

the islands include the introduction and spread of feral 

ungulates that can uproot forest vegetation and exacerbate 

erosion, and the spread of nonnative species that can affect 

forest composition and resilience to wildfire, particularly 

in the Pacific. Apart from these biological pressures and 

outright forest conversion, very few of the islands’ forests 

are threatened by unsustainable or large-scale commercial 

timber harvesting or other intensive, extractive uses. So, it 

is expected that their continued recuperation, growth, and 

protection will likely lead to improved forest soil properties and overall forest health. 

In Puerto Rico, most of the upper watersheds and forested 

slopes are associated with relatively well-preserved soil 

resources, as these areas largely have eluded land cover 

change or intensive harvesting and other uses owing 

to their limited access, steep slopes, and more recent 

conservation policies (Larsen et al. 1999). However, much 

of the island’s forest area (about 80 percent) has only 

recently (<50 years) regenerated on abandoned agriculture 

and grazing lands, where such land use often led to soil 

compaction and degradation (Lugo and Helmer 2004). 

These secondary or “novel” forests have been found to 

demonstrate “poor development of the interface between 

the mineral soil, the humus layer, and the litter layer, [such 

that the] soil interface is abrupt and lacks the rich organic 

matter horizon that is typical of mature native forest” 

(Lugo and Helmer 2004). On average, new forests in wet 

life zones are associated with lower soil bulk density than 

mature native wet forests, largely because of higher soil 

compaction from previous human uses that is typical of 
Assessing Forest Sustainability in the Tropical Forests of the United States II–51

secondary forests (Lugo and Helmer 2004). Consequently, 

most of Puerto Rico’s forest soils are poorly developed 

and, in many cases, degraded, but continued forest growth 

and recuperation are likely to lead to enhanced soil 

conditions across the islands. 

Although there are no available quantitative data on soil 

quality for the USVI, the extent of soil degradation from 

current forest use is considered minimal, because forests 

are not commercially harvested for timber production, 

recreation is managed, for the most part, and other 

forest uses have relatively limited effects on the soil 

resources. Similarly to Puerto Rico, however, much of 

the USVI’s forested land has regenerated over degraded 

and compacted soils resulting from previous land uses, 

such as agriculture and grazing. Moreover, forests in 

the USVI are increasingly converted to housing, roads, 

and commercial and industrial development. These land 

use changes are associated with increased erosion and 

sediment yields within the watershed and downstream 

ecosystems, including nearshore coral reefs and other 

marine communities, which are highly sensitive to fine 

sediment inputs (MacDonald et al. 1997, Ramos-Scharron 

and MacDonald 2007). 

In Hawaii, a long history of land use conversion, nonnative animal and plant species introductions, and 

intensive timber harvesting have affected much of the 

islands’ forests and associated soil resources, though no 

data are available to quantitatively describe the extent 

of these effects or assess forest soil conditions or trends 

in general. Presently, feral ungulates (e.g., pigs, goats, 

sheep, deer, cattle) that tear up, trample, and uproot forest 

vegetation, often leaving the forest floor overturned or 

bare, represent a significant threat to forest soils across 

the Hawaiian Islands (Hess et al. 2006). These activities 

make the soil more susceptible to erosion and increase 

the dispersal and germination of fast-growing nonnative 

species, which in turn can shade out native understory 

species and ultimately modify the forest habitat (Hess 

et al. 2006). Some nonnative plants, such as Miconia 

calvescens, have shallow roots that, once established, also 

reduce the ability of forests on steep slopes to withstand 

erosion, rockfall, and landslides (State of Hawaii 2010). In 

response to the devastating effects of feral pigs and other 

ungulates on native Hawaiian vegetation, numerous public, private, and joint initiatives have been established to 

implement management techniques that deal specifically 

with these animals, such as fencing, snaring, and other 

population controls (Hess et al. 2006), but there are no 

quantitative data measuring the extent of these activities 

or their outcomes. 

Wildfires and grazing by nonnative ungulates influence 

Hawaiian forests and soils by removing woody vegetation 

and ground cover, exposing soil to raindrops, and removing barriers to erosion. Many Hawaiian and other tropical 

island forests are subject to frequent tropical downpours, 

and occasional but intense downpours occur even in dry 

forest areas. These events can quickly cause erosion and 

landslides in disturbed areas. 

In many U.S.-affiliated Pacific Islands, much of the 

forested area is found on steep slopes (in most cases >50 

percent) (Harp et al. 2004). These areas are affected by 

typhoons and other periods of heavy rain that may result 

in slopewash and landslides, depending on the land use 

and severity of the storm. Tropical storms and typhoons 

develop frequently in Micronesia and affect forests, other 

natural systems, and human settlements, particularly 

where sustainable land use planning and practices are not 

implemented (Harp et al. 2004). 

The clearing or conversion of forests to other land uses 

throughout the Pacific Islands has had a significant effect 

on soil stability, particularly in upper watersheds and 

on steep slopes. For example, in Pohnpei, FSM, illegal 

clearing of forest for the cultivation of sakau along riverbanks in the primary upper watershed is thought to cause 

significant erosion and sedimentation of lowland areas. 

Collaborative conservation programs in Pohnpei that 

integrate alternative income generation with increased 

monitoring and enforcement have had measurable success 

in decreasing the number of new forest clearings (e.g., 

down from more than 600 clearings in 2002 to 5 in 2007) 

(Conservation Society of Pohnpei 2012).

In Palau, poorly built roads and trails are a major source 

of sediment to streams and nearshore marine communities 

(MacKenzie 2015). Additionally, unintentional and unauthorized burns and wildfires increasingly affect forests, 

particularly with the completion of the Compact Road, 

which facilitates greater access to once remote areas of 

Palau. 

In Guam, the rough topography of limestone forests in 

the north has discouraged land use practices that would 

otherwise have resulted in erosion and other types of 

soil degradation (Minton 2005). Conversely, in southern 

Guam, historical deforestation has resulted in a landscape 

dominated by savanna and badlands devoid of vegetation, 

with degraded soils. These savannas and badlands are 

maintained by frequent intentional (e.g., for grazing) and 

unintentional human-induced burning and feral ungulate 

grazing, which prevent forest regeneration and degrade 

the remaining forest by burning in from the edges. 
II–52 Assessing Forest Sustainability in the Tropical Forests of the United States

Ultimately, the burning and loss of soil surface cover have 

resulted in erosion, mass wasting, and increased landslides throughout much of southern Guam (Minton 2005). 

Indicator 4.21

Degraded or Diminished Water 

Bodies or Ways in Forest Areas

Water is one of the most valuable of ecosystem services 

provided by island forests, but there is very limited 

comparable quantitative data on the quantity or quality of 

water resources in forested areas. The extensive area of 

forested land across the islands contributes significantly 

to the protection of water resources within and outside 

forests. The conversion of forest lands to other uses has 

significantly affected water availability and quality on 

many of the islands. In most island contexts, nonforest 

land uses such as agriculture and development (i.e., urban, 

industrial, tourism) have led to the overuse of existing 

water supplies, sedimentation of water reservoirs, and 

contamination of surface and ground waters. 

The Clean Water Act (CWA) Section 305(b) requires 

states and other U.S.-affiliated jurisdictions to assess 

the quality of waterways, bodies, and other resources 

and regularly report the findings to the Environmental 

Protection Agency (EPA). This legislation requires states 

and other jurisdictions to identify reportable waterways 

and bodies, designate appropriate water uses for each, 

assess attainment of established water quality standards, 

and determine the principal sources of impairment. Each 

state or jurisdiction determines its own standards for 

water quality, which must be in compliance with the CWA 

and approved by the EPA, but which may not be comparable across states and other jurisdictions. Although these 

statistics do not directly measure the quality of forest 

water resources, they do reflect the state of waterways and 

bodies in most of the island jurisdictions included in this 

report. Five of the island jurisdictions reported on water 

quality in 2010. Puerto Rico, Hawaii, American Samoa, 

and the Marianas reported that the majority of assessed 

waters in 2010 were impaired or otherwise compromised, 

largely owing to the effects from agriculture and urban 

land uses, indicating in part at least the need for continued 

and enhanced forest and watershed protection (USEPA 

2010). Guam was the only jurisdiction to report that a 

minority of its assessed waters were impaired (USEPA 

2010).

Water quality in the USVI was not reported to the EPA 

in 2010, owing in large part to the absence of perennial 

streams and rivers and limited supply of aboveground 

reservoirs and ground water resources. Nevertheless, 

fresh water supplies are scarce in the USVI, and human 

activities have further exacerbated water scarcity, particularly as intermittent waterways and other natural 

channels that once permitted the absorption of water into 

the water table have been paved over or converted to other 

land uses. Since the early 1930s, private residences and 

businesses have been required by law to construct cisterns 

for the capture and storage of rainwater from rooftops 

and other impermeable surfaces in the USVI. Nevertheless, increasing demands on water sources and supplies 

eventually led to the construction of a desalination plant 

on St. Croix and another on St. Thomas in the 1960s. By 

the mid-1990s, these plants produced about 65 percent of 

the islands’ freshwater supply (ground water provides 22 

percent, cisterns 13 percent) and were noted for producing 

the most expensive publicly supplied water in the United 

States ($4.20/1000 liters) (Zack and Larsen 1994). 

In Puerto Rico, fresh water supply and maintenance are 

vital for supporting the island’s sizeable population (>3.7 

million persons; 1,085 persons/mi2 ) (USDC CB 2010). 

And, although the headwaters of the major rivers and 

streams, which supply most of the island’s 25 reservoirs, 

lie within protected forested areas, few watersheds remain 

untapped, and the number of dams and water intakes in 

Puerto Rico’s forests continues to increase (March et al. 

2003). For example, Crook et al. (2007) quantified the 

amount of water withdrawn from El Yunque National 

Forest (EYNF) in 2004. They found that on an average 

day, 70 percent of the median flow of the water generated 

in the EYNF was diverted for municipal use. These 

water withdrawal levels could potentially alter “stream 

habitat for migratory shrimps and fishes, and also change 

the dynamics of downstream transport of sediment, 

suspended particles, and other food and energy sources 

to estuaries” (Crook et al. 2007: 17–18). Moreover, water 

withdrawal from the EYNF is expected to increase in the 

future, “creating management challenges” for the forest 

and its watersheds (Crook et al. 2007). 

In Puerto Rico, the conversion of forests to agricultural, 

industrial, and residential use, and increasing population 

and urban density have affected the physical, chemical, 

and biological properties of most waterways and bodies 

(see, for example, Heartsill-Scalley and Aide 2003, 

Lopez et al. 1998, Lugo et al. 2001). Forest conversion, 

in particular, has significantly affected water availability 

and quality, including overutilization of existing water 

supplies, sedimentation of water reservoirs, and the 

contamination of surface and ground waters (Zack and 
Assessing Forest Sustainability in the Tropical Forests of the United States II–53

Larsen 1994). Many of Puerto Rico’s principal reservoirs 

have become at least partially filled with sediment, owing 

to the effects of forest land use change and unsustainable 

land use practices, reducing their effectiveness in water 

provision and flood mitigation. By the mid-1990s, most 

of the major water reservoirs in Puerto Rico stored, on 

average, about 32 percent of their original storage capacity, attributed largely to sedimentation from inadequate 

land use practices (Zack and Larsen 1994). Furthermore, 

as of 2010, much of Puerto Rico’s public water supply 

(60 percent of the 85 percent assessed) was considered 

“impaired” under the CWA reporting requirements and 

failed to meet local water quality standards for at least one 

designated use (table C4-1). Impairment to waterways and 

bodies was attributed to municipal discharges, agriculture, and urban runoff (USEPA 2010). 

Similarly to Puerto Rico, most of the waters assessed in 

Hawaii for EPA reports on water quality do not meet local 

water quality standards for at least one of their designated 

uses and are considered “impaired.” Other than the data 

presented in table C4-1, there are no available quantitative 

data on forest water resources for Hawaii. Nonetheless, 

many of the state’s rivers and streams have been partially 

or fully altered (channelized, diverted, or tapped via 

ground-water pumping) and those that remain are considered to be vulnerable to continued pressure as the demand 

for fresh water outpaces the supply (State of Hawaii 

2010). Moreover, Hawaii’s watersheds and (downstream) 

freshwater habitats have been significantly affected by 

nonpoint source pollution, sedimentation, storm water 

runoff, and wildfire (State of Hawaii 2010). 

Water resources within forested areas in Hawaii are 

indirectly altered by three major agents: feral ungulates, 

nonnative fish, and nonnative plants. Nonnative ungulates 

affect native vegetation that has no natural protective 

measures against these animals. Ungulates not only 

consume and destroy forest ground cover but uproot and 

expose the soil to increased erosion, which often leads 

to sedimentation of forested waterways and bodies. 

Additionally, feral ungulates and other feral animals (e.g., 

rats, cats, dogs, mongoose) affect water quality by serving 

as vectors for water-borne diseases such as leptospirosis 

and cryptosporidiosis. Similarly, nonnative plants have 

had negative effects on the hydrologic processes of 

Hawaii’s forested watersheds. Some nonnative species, 

such as miconia (Miconia calvescens), have been shown 

to increase water runoff and decrease the infiltration of 

rainwater belowground and into the aquifer. Falcataria 

moluccana, a nitrogen-fixing nonnative plant, has been 

shown to increase significantly nitrogen concentrations 

in streams that were formerly nitrogen limited; thus, the 

spread of Falcataria results in algal blooms and, ultimately, decreased water quality in streams and downstream nearshore areas (MacKenzie 2015, State of Hawaii 

2010).

Similarly to Hawaii, forest water resources in the U.S.-

affiliated Pacific Islands are affected by water diversions, 

feral ungulates, nonnative invasive plants and fish, and 

Table C4-1. Water-quality data for five jurisdictions in the Caribbean and the Pacific, 2010

Puerto Rico Hawaii

American 

Samoa

Northern 

Marianas Guam

Type of water body

Rivers and 

streams

Lakes, 

reservoirs, 

and ponds

Rivers and 

streams

Lakes, 

reservoirs, 

and ponds

Rivers and 

streams

Rivers and 

streams

Miles Acres Miles Acres - - - - - - - Miles - - - - - - -

Estimated total waters 5,394 12,146 3,905 45.2 257.5 228.7

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Percentage of total waters assessed 88.5 71.1 0.2 ND 89.6 37.0

Percentage of total assessed 

 waters—Impaireda 84.8 93.7 100 100 91.1 34.2

Percentage of assessed waters 

 designated as public water supply

77.4 84.8 ND 100 ND 58.3

Percentage of assessed public 

 waters—Impaired 

85.3 60.3 ND 100 ND 7.1

a

 Impaired = cannot support one or more designated use.

ND = no data. 

Source: USEPA 2010.
II–54 Assessing Forest Sustainability in the Tropical Forests of the United States

pollutants such as bacteria, nutrients, chlorides, and toxic 

contaminants that result from human activities. Although 

water resources and the protection of their quantity and 

quality are important to these islands, very little quantitative, regularly collected data related to this indicator 

were available at the time this report was prepared, with 

the exception of data on water quality reported to the EPA 

by American Samoa, Guam, and the Northern Mariana 

Islands (table C4-1). Guam reported that the majority of 

its assessed rivers and streams meet local water quality 

standards, while most of the assessed waters in American 

Samoa and the Marianas did not meet local water quality 

standards for at least one of their designated uses. In 

American Samoa, impairment to waterways and bodies 

was attributed to agriculture, livestock, and municipal 

discharges. Guam and the Marianas did not report on 

impairment causes.

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Russell and Sidney Poore
Assessing Forest Sustainability in the Tropical Forests of the United States II–57

Criterion 5

Assessing Forest Sustainability in the Tropical Forests of the United States

Maintenance of Forest Contribution to Global Carbon Cycles

Kathleen S. Friday

Introduction

Increasing carbon dioxide (CO2) in the atmosphere is 

driving global climate change, including overall warming 

and sea-level rise, with consequences for the sustainability of world ecosystems and economies. The effects 

of climate change on forest health are discussed under 

Criterion 3. The effects of forests and forest management 

on carbon cycles are discussed here. Forests are one 

of the largest terrestrial reservoirs of biomass and soil 

carbon. Total forest ecosystem carbon is encompassed 

by the following components, or “pools”: standing wood; 

other live aboveground biomass (bark, branches, foliage, 

and smaller plants); live belowground biomass (roots); 

lying and standing coarse woody debris (dead trees and 

limbs); and soil carbon. The amount of carbon in each 

pool is the stock, expressed in mass (weight) of carbon 

(C). Forests influence the chemical composition of the 

atmosphere, which is also a carbon pool. Vegetation 

draws CO2 from the atmosphere through photosynthesis, 

and returns it through respiration, including that from 

the decay of organic matter. Carbon fluxes refer here 

to net changes in carbon stocks. Carbon sequestration

(positive flux) refers to net storage of carbon in the forest, 

as opposed to net loss of carbon (negative flux) to the 

atmosphere. Carbon stocks and fluxes per unit area differ 

by forest type (including climatic life zone), by age class 

or successional stage, and by management regime. Wet 

forest pools tend to be larger and faster growing than dry 

forests; tropical forests are faster growing than temperate 

forests. Disturbance (including harvesting and fire) 

typically reduces total carbon stored in the live forest, at 

least in the short term. Forest products are also a pool of 

carbon. When a tree is harvested, its wood may be stored 

in long-lived products for years, while the forest (from 

which it was taken) sequesters more carbon as it grows 

back. Forest products thus delay the release of carbon into 

the atmosphere.

Energy produced from forest biomass may offset the need 

to burn fossil fuels, while the forest from which it was 

taken sequesters more carbon as it regrows. The use of 

renewable forest resources for energy thereby benefits the 

global carbon budget and lowers net carbon emissions in 

the medium to long term. 

Criterion Summary

Carbon stock estimates available for the different islands 

differ considerably owing to the size of each island, differences in actual conditions among islands, and different 

estimation techniques used. Compared to continental 

forests, total island carbon stocks are small, although 

some stocks are large per unit area, such as soils of island 

forested wetlands. Islands have focused on adaptation 

(managing effects of climate change); climate change is 

widely considered a cross-cutting issue threatening forest 

biodiversity and forest extent (Criterion 1) and forest 

health (Criterion 3), freshwater resources (Criterion 4) , 

coastal and marine resources, and migration. Islands have 

had relatively little focus on mitigation (managing carbon 

stocks and fluxes), although where per-acre fluxes are 

potentially large, there are opportunities for sequestration 

incentives and bioenergy generation, subject to data 

limitations, socioeconomic conditions (Criterion 6), and 

institutional capacity (Criterion 7) .

The Indicators

Carbon stocks and fluxes are estimated by various techniques and metrics. Measurements may include different 

components of the total forest ecosystem: trees or shrubs; 

live or dead biomass; wood or other vegetative material; 

and aboveground or belowground biomass. Different conversion factors may be applied to convert local field data 

into total carbon estimates. The Forest Service’s Forest 

Inventory and Analysis (FIA) program provides data for 

aboveground live trees using a consistent methodology 

in the U.S.-affiliated Pacific Islands (west of Hawaii): 

FIA plot data for live trees at least 5 inches in diameter at 

breast height (≥5inches dbh) were converted to C mass of 

woody stems and extrapolated using contemporary forest 

extent maps for each island. FIA carbon estimates for 

Puerto Rico and the U.S. Virgin Islands (USVI) included 

live trees ≥1 inch dbh, but noted the percentages of biomass in the 1 to 4.9-inch dbh class (27 percent in Puerto 

Rico, 67 percent in the USVI), thus facilitating comparison with the Pacific (Brandeis and Turner 2013a, 2013b). 

Asner et al. (2016) estimated biomass for Hawaii based on 

a combination of LiDAR and satellite imagery validated 

by FIA plot data. Donato et al. (2012) extrapolated plot 

data (stems ≥2 inches dbh) over three mapped vegetation 

types in Yap and Palau, and also measured soil carbon.
II–58 Assessing Forest Sustainability in the Tropical Forests of the United States

Estimates of total carbon stocks for the U.S.-affiliated 

Pacific Islands are based on FIA plot data extrapolated 

using standard United Nations Food and Agriculture 

Organization (FAO) and International Panel on Climate 

Change (IPCC) conversion factors (FAO 2008). For 

Hawaii, Asner et al. (2011) found that their estimates were 

much lower than if the same field data were interpreted 

using IPCC conversion factors. For Palau, Donato et al. 

(2012) had results roughly a third lower than Donnegan 

and Holm (2010) using IPCC methodology.

Few data are available concerning forest product carbon 

stocks and fluxes, or avoided fossil fuel carbon emissions.

• 5.22: Total forest ecosystem carbon pools and fluxes.

• 5.23: Total forest product carbon pools and fluxes.

• 5.24: Avoided fossil fuel carbon emissions by using 

forest biomass for energy.

Indicator 5.22

Total Forest Ecosystem Carbon 

Pools and Fluxes

Stocks in Carbon Pools 

Total jurisdiction carbon (C) stocks in vegetation range 

from 0.28 to 39.67 million tons, depending upon the 

size of each island, the nature of its forest, and differing 

vegetation pools and methodologies (table C5-1). For the 

U.S.-affiliated Pacific Islands, Donnegan et al. (2004a, 

2004b, 2007, 2011a, 2011b, 2011c) provide C estimates for 

woody stems of trees for the year in which FIA plots were 

installed. Donnegan (2010a, 2010b, 2010c, 2010d, 2010e), 

and Donnegan and Holm (2010) provided estimates of carbon in aboveground living tree biomass and aboveground 

and belowground living tree biomass using the same 

Table C5-1. Total carbon stocks per island jurisdiction

Island jurisdiction (year of inventory)

In woody stems 

of trees 

≥5 inches dbh

In aboveground 

living forest 

biomass

In aboveground 

living tree 

biomass

In aboveground 

and belowground 

living tree biomass

- - - - - - - - - - - - - - - - - - - Thousand tons of carbon stock - - - - - - - - - - - - - - - - - - - 

U.S. Virgin Islands (2009) 609 737

Puerto Rico (2009) 22,537 27,016

Hawaii (~2009–2014) 39,672

American Samoa (2001, 2010a) 539 1,726 2,140

Republic of the Marshall Islands (2008, 

2010 a)

427 2,006 2,546

Federated States of Micronesia (2005–2006, 

 2010 a)

4,545 17,676 22,459

Saipan, Tinian, Rota [Commonwealth of the 

Northern Mariana Islands] (2004, 2005b)

281 1,796 2,281

Guam (2002) 490 1,561 1,982

Republic of Palau (2003, 2010 a) 2,297 9,246 11,747

a

 Aboveground and belowground living tree biomass was extrapolated forward from date of inventory to 2010 by Donnegan (2010a, 2010c, 2010e).

b

 Aboveground and belowground living tree biomass was extrapolated forward from date of inventory to 2005 by Donnegan (2010b).

dbh = diameter at breast height. 

Source: Asner et al. 2016; Brandeis and Turner 2013a, 2013b; Donnegan 2010a, 2010b, 2010c, 2010d, 2010e; Donnegan and Holm 2010; 

Donnegan et al. 2004a, 2004b, 2007, 2011a, 2011b, 2011c.
Assessing Forest Sustainability in the Tropical Forests of the United States II–59

data but extrapolated forward to 2010. For the Caribbean, 

Brandeis and Turner (2013a, 2013b) also provided estimates of carbon in aboveground living tree biomass for 

2009, based on data for trees ≥1 inches dbh in that year. 

Hawaii’s data are drawn from FIA plots installed over a 

period of about 6 years. 

Jurisdiction average carbon stocks per unit of forested 

land range from 5.6 to 29.2 tons of carbon per acre, and 

again are shown based on differing vegetation pools and 

methodologies (table C5-2). Carbon stocks are spatially 

heterogeneous in the islands; in Hawaii, the highest 

forest stand aboveground carbon density reached 240 

tons C/ac (Asner et al. 2016).

Inclusion of the soil carbon pool results in larger figures 

for stocks. In Puerto Rico, additional plot data on downed 

wood and forest litter was also used to estimate total 

(above- and belowground, living and dead, litter and 

forest floor) carbon stock of 40.3 million tons (Brandeis 

et al. 2007). Donato et al. (2012) noted that the deep 

organic soils of Micronesian mangroves store more carbon 

per unit area (281 to 336 tons C/ac) than all other pools 

combined on those islands. Using different methodologies, 

Donato et al. (2012) had significantly different summaries 

of total carbon stocks. FIA-based estimates in table C5-1 

show Palau’s living tree stock as 2.3 to 11.7 million tons; 

Donato et al. estimated that Palau’s living tree stock is 

7.3 million tons and its total carbon stock, including 

mangrove soils, is 16.8 million tons. 

Carbon Fluxes

Carbon fluxes for the U.S.-affiliated Pacific Islands may 

be quantifiable by future analysis of 2012–2018 remeasurement of FIA plots (see chapter 2). Carbon stocks 

inferred from Pacific timber inventories of the 1980s (for 

Table C5-2. Carbon stocks per unit area of forest for each island jurisdiction

Island jurisdiction (year of inventory)

In woody stems 

of trees 

≥5 inches dbh

In aboveground 

living forest 

biomass

In aboveground 

living tree 

biomass

In aboveground 

and belowground 

living tree biomass

- - - - - - - - - - - - - - - - - - Tons of carbon per forested acre - - - - - - - - - - - - - - - - - 

U.S. Virgin Islands (2009) 13.5 16.0

Puerto Rico (2009) 18.5 22.0

Hawaii (~2009–2014) 29.2

American Samoa (2001) 12.4

Republic of the Marshall Islands (2008) 18.4

Federated States of Micronesia (2005–2006) 31.7

Commonwealth of the Northern Mariana 

 Islands: Saipan, Tinian, Rota (2004)

5.6

Guam (2002) 7.7

Republic of Palau (2003) 25.3

dbh = diameter at breast height.

Source: Asner et al. 2016; Brandeis and Turner 2013a, 2013b; Donnegan and Holm, 2010; Donnegan et al. 2004a, 2004b, 2007, 2011a, 2011b, 2011c.
II–60 Assessing Forest Sustainability in the Tropical Forests of the United States

example, Cole et al. 1988) cannot be directly compared 

with carbon stocks based on total forest biomass from 

2001–2007 FIA data; therefore flux cannot be quantified 

over that two-decade interval. Because there are few 

data now available for carbon fluxes, table C5-3 presents 

change in forest area and other published observations for 

an entire jurisdiction as a proxy for carbon flux. 

Positive carbon sequestration rates in Puerto Rico are 

inferred from net shifts of agricultural land to forest land 

from 1980 to 2003 (Brandeis et al. 2007) and high rates 

of sequestration by young secondary forests (Grau et al. 

2003, further explained under Criterion 2). Brandeis and 

Turner (2013a) calculated a net gain of 170 million cubic 

feet of wood during 2004–2009 (considering growth, mortality, harvesting, and clearing) and described Puerto Rico 

as a carbon sink. Likewise, for the USVI, Brandeis and 

Turner (2013b) calculated a net gain of 4.7 million cubic 

feet of wood during 2004–2009. Sequestration is taking 

place on forested land, owing to the early successional 

stage of forests (as in Puerto Rico). During 1994–2004, 

there were net losses of forest carbon resulting from the 

loss of forested area (Brandeis and Oswalt 2007), but 

forest loss during 2004–2009 slowed and approached 

stability (Brandeis and Turner 2013b).

Stocks of carbon in living biomass in Guam are assumed 

to fluctuate with typhoons, as total forest area is fairly 

stable but frequent typhoons cause damage, followed by 

sequestration as forests recover. The clearing of mangrove forests may have a large impact on carbon fluxes if 

significant portions of the soil organic matter are oxidized 

(Donato et al. 2012). Plantations of Eucalyptus spp. 

(Hawaii) or rapid growth of large trees such as Falcataria 

moluccana (especially in Hawaii and American Samoa) 

sequester large amounts of carbon; because these species 

are not native, such sequestration entails a tradeoff with 

biodiversity values (Hughes et al. 2014).

Indicator 5.23

Total Forest Product Carbon

Pools and Fluxes

Less than 0.01 percent of Puerto Rico’s annual forest 

wood production was harvested for wood products 

(Brandeis et al. 2007), and 0.13 percent was harvested 

for any purpose including clearing (Brandeis and Turner 

2013a). Overall, the amount of carbon being removed as 

wood products from Puerto Rico’s forests is negligible 

compared to that being stored, and accumulating, in the 

forest vegetation, floor, and soils. Likewise, the amount of 

Table C5-3. Trends contributing to flux in carbon stocks by jurisdiction

Island jurisdiction and time frame

Carbon sequestration 

per unit area of forest

Change in 

forest area

Flux

(per jurisdiction)

Percent 

U.S. Virgin Islands:

 1994–2004 Positive -7 Negative

 2004–2009 Stable Positive

Puerto Rico:

 2003 Positive Positive Positive

 2004–2009 Stable Positive

Hawaii Unknown

American Samoa (1986–2001) -3 Negative

Republic of the Marshall Islands Unknown

Federated States of Micronesia (2005) Slightly positive

Commonwealth of the Northern Mariana Islands (2005) Negative Negative

Guam (2000) Negligible Fluctuating

(typhoons)

Republic of Palau (2005) Positive May be at a peak Unknown

Sources: Brandeis and Oswalt 2007; Brandeis and Turner 2013a, 2013b; Brandeis et al. 2007; Donnegan 2010a, 2010b, 2010c, 2010d, 2010e; 

Donnegan and Holm 2010; Donnegan et al. 2004b.
Assessing Forest Sustainability in the Tropical Forests of the United States II–61

carbon being removed as forest products from the forests 

of the USVI is nominal (Pierce and Hultgren 1997). 

Harvesting for wood products in Hawaii is primarily for 

low-volume, high-value woods; large-scale harvesting 

of Eucalyptus spp. plantations was not yet underway by 

2010. Data are not available for the other Pacific Islands, 

but because wood products are harvested only for local 

and subsistence use, it may be assumed that sequestration 

in wood products of Pacific Island origin is not significant 

locally or globally.

Indicator 5.24

Avoided Fossil Fuel Carbon Emissions

By Using Forest Biomass for Energy

No data were available for Puerto Rico and the USVI 

at the time this report was prepared. The use of forest 

biomass for energy in Hawaii was still at the trial stage in 

2010. Fuelwood is commonly used in the Federated States 

of Micronesia and some other Pacific islands as an extension of traditional and subsistence use for cooking, and as 

a substitute for more expensive imported energy, but data 

documenting this use are not available, and overall effects 

on carbon emissions are likely insignificant. Coconut oil 

(a forest product) is being used in the Marshall Islands as 

a substitute for fossil fuels for vehicles, but quantitative 

data are likewise lacking. 

References

Asner, G.P.; Hughes, R.F.; Mascaro, J.; Uowolo, A.L.; 

Knapp, D.E.; Jacobson, J.; Kennedy-Bowdoin, T.; 

Clark, J.K. 2011. High-resolution carbon mapping on 

the million-hectare island of Hawaii. Frontiers in Ecology 

and the Environment. 9: 434–439.

Asner, G.P.; Sousan, S.; Knapp, D.E.; Selmants, P.C.; 

Martin, R.E.; Hughes, R.F.; Giardina, C.P. 2016.

Rapid forest carbon assessments of oceanic islands: 

a case study of the Hawaiian archipelago. Carbon 

Balance and Management. 11: 1–13.

Brandeis, T.J.; Helmer, E.H.; Oswalt, S.N. 2007.

The status of Puerto Rico’s forests, 2003. Resour. 

Bull. SRS-119. Asheville, NC: U.S. Department 

of Agriculture, Forest Service, Southern Research 

Station. 75 p.

Brandeis, T.J.; Oswalt, S.N. 2007. The status of U.S. 

Virgin Islands’ forests, 2004. Resour. Bull. SRS-122. 

Asheville, NC: U.S. Department of Agriculture, Forest 

Service, Southern Research Station. 61 p.

Brandeis, T.J.; Turner, J.A. 2013a. Puerto Rico’s 

forests, 2009. Resour. Bull. SRS-RB-191. Asheville, 

NC: U.S. Department of Agriculture, Forest Service, 

Southern Research Station. 85 p.

Brandeis, T.J.; Turner, J.A. 2013b. U.S. Virgin Islands’ 

forests, 2009. Resour. Bull. SRS-196. Asheville, NC: 

U.S. Department of Agriculture, Forest Service, 

Southern Research Station. 56 p.

Cole, T.G.; Whitesell, C.D.; Whistler, W.A.; McKay, 

N.; Ambacher, A.H. 1988. Vegetation survey and 

forest inventory, American Samoa. Resour. Bull. 

PSW-25. Albany, CA: U.S. Department of Agriculture, 

Forest Service, Pacific Southwest Research Station. 

14 p.

Donato, D.; Kauffman, J.B.; MacKenzie, R.;

Ainsworth, A.; Pfleeger, A. 2012. Whole-island 

carbon stocks in the tropical Pacific: implications for 

mangrove conservation and upland restoration. Journal 

of Environmental Management. 97: 89–96. 

Donnegan, J. 2010a. Global forest resources assessment: 

country report—American Samoa. FRA2010/004. 

Rome: Food and Agriculture Organization of the 

United Nations, Forestry Department. http://www.fao.

org/docrep/013/al440E/al440E.pdf. (March 2017).

Donnegan, J. 2010b. Global forest resources assessment: 

country report—Guam. FRA2010/083. Rome: Food 

and Agriculture Organization of the United Nations, 

Forestry Department. http://www.fao.org/docrep/013/

al519E/al519E.pdf. (February 2017).

Donnegan, J. 2010c. Global forest resources assessment: 

country report—Marshall Islands. FRA2010/127. 

Rome: Food and Agriculture Organization of the 

United Nations, Forestry Department. http://www.fao.

org/docrep/013/al562E/al562E.pdf. (February 2017).

Donnegan, J. 2010d. Global forest resources assessment: 

country report—Micronesia (Federated States 

of). FRA2010/133. Rome: Food and Agriculture 

Organization of the United Nations, Forestry 

Department. http://www.fao.org/docrep/013/al568E/

al568E.pdf. (February 2017).

Donnegan, J. 2010e. Global forest resources 

assessment: country report—Northern Mariana 

Islands. FRA2010/154. Rome: Food and Agriculture 

Organization of the United Nations, Forestry 

Department. http://www.fao.org/docrep/013/al589E/

al589E.pdf. (February 2017).
II–62 Assessing Forest Sustainability in the Tropical Forests of the United States

Donnegan, J.; Butler, S.; Grabowiecki, W.; Hiserote, 

B.; Limtiaco, D. 2004a. Guam’s forest resources, 

2001. Resour. Bull. PNW-RB-243. Portland, OR: 

U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station. 32 p.

Donnegan, J.; Butler, S.; Kuegler, O.; Hiserote, B.

2011a. Commonwealth of the Northern Mariana 

Islands’ forest resources, 2004. Resour. Bull. 

PNW-RB-261. Portland, OR: U.S. Department 

of Agriculture, Forest Service, Pacific Northwest 

Research Station. 40 p.

Donnegan, J.; Butler, S.; Kuegler, O.; Hiserote, B.

2011b. Federated States of Micronesia forest resources, 

2006. Resour. Bull. PNW-RB-262. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 50 p.

Donnegan, J.; Butler, S.; Kuegler, O.; Stroud, B.;

Hiserote, B.; Rengulbai, K. 2007. Palau’s forest 

resources, 2003. Resour. Bull. PNW-RB-252. Portland, 

OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station. 52 p. http://www.

treesearch.fs.fed.us/pubs/25880. (September 2016).

Donnegan, J.; Holm, T. 2010. Global forest resources 

assessment 2010: country report—Palau. FRA2010/159. 

Rome: Food and Agriculture Organization of the 

United Nations, Forestry Department. http://www.fao.

org/docrep/013/al594E/al594E.pdf. (March 2017).

Donnegan, J.; Mann, S.; Butler, S.; Hiserote, B. 2004b. 

American Samoa’s forest resources, 2001. Resour. 

Bull. PNW-RB-244. Portland, OR: U.S. Department 

of Agriculture, Forest Service, Pacific Northwest 

Research Station. 32 p. http://www.treesearch.fs.fed.us/

pubs/7541. (September 2016).

Donnegan, J.; Trimble, S.; Kusto, K.; Kuegler, O.;

Hiserote, B. 2011c. Republic of the Marshall Islands 

forest resources, 2008. Resour. Bull. PNW-RB-263. 

Portland, OR: U.S. Department of Agriculture, Forest 

Service, Pacific Northwest Research Station. 29 p.

Food and Agriculture Organization of the United

Nations [FAO]. 2008. Global forest resources 

assessment 2010: guidelines for country reporting to 

FRA 2010. Final draft, Working Paper 143. Rome: 

Forestry Department.

Grau, H.R.; Aide, T.M.; Zimmerman, J.K.; 

Thomlinson, J.R.; Helmer, E.; Zou, X. 2003. The 

ecological consequences of socieconomic and land-use 

changes in postagriculture Puerto Rico. BioScience. 

53(12): 1159–1168.

Hughes, R.F.; Asner, G.P.; Mascaro, J; Uowolo, A.; 

Baldwin, J. 2014. Carbon storage landscapes of 

lowland Hawaii: the role of native and invasive species 

through space and time. Ecological Applications. 

24(4): 716–731.

Pierce, S.; Hultgren, P., eds. 1997. Forest products of 

the U.S. Virgin Islands: an overview of trends in forest 

products use. St. Croix, VI: Virgin Islands Resource 

Conservation and Development Council. 31 p.

Portable sawmill in Palau milling Swietenia macrophylla (Honduran mahogany), a nonnative species that is produced 

for local use and limited exports. Local uses include furniture and elaborately carved storyboards that illustrate 

Palauan legends.

Kathleen Friday
Assessing Forest Sustainability in the Tropical Forests of the United States II–65

Criterion 6

Assessing Forest Sustainability in the Tropical Forests of the United States

Maintenance and Enhancement of Long-Term Multiple 

Socioeconomic Benefits to Meet the Needs of Societies

Guy C. Robertson and Constance A. Carpenter

Introduction

Through an emphasis on concepts such as the “triplebottom-line,” researchers and sustainability advocates 

have highlighted the linkages between social and economic measures of sustainability and those from the 

ecological realm (Floyd 2002). The Montréal Process 

Criteria and Indicators (MP C&I) mainly address the 

socioeconomic dimensions of forest sustainability in Criterion 6 (“Maintenance and Enhancement of Long-Term 

Socioeconomic Benefits to Meet the Needs of Societies”), 

whose 20 indicators are arranged into five subcriteria and 

cover an array of topics, ranging from forest products 

trade and production to spiritual benefits from forests 

and the well-being of forest-dependent communities. 

The following chapter applies Criterion 6 to the U.S. and 

U.S.-affiliated tropical islands considered in this report.

Forests are often essential to the well-being of island 

populations. Small and isolated island ecologies reinforce 

the linkages among forests, agriculture, and coastal 

fisheries. Traditional economies and subsistence activity 

make use of the total ecosystem, including forests, and 

tourism relies on the unique beauty provided by healthy 

island ecosystems (of which forests are an integral part). 

Historical and archaeological analysis of places like 

Easter Island has highlighted the crucial linkage between 

human populations and forest resources, and conveys 

the tragic results when forests are not sustained (Rolett 

and Diamond 2004). Nevertheless, the discrete and 

heterogeneous island geographies that are the subject of 

this report present several challenges when applying the 

Criterion 6 indicators of the MP C&I. In the first place, 

many of the island jurisdictions considered here lack a 

well-defined forest sector from which statistical measures 

can be drawn. Most, in fact, have little or no industrial 

wood products manufacturing and therefore no “forest-dependent” economic activities or communities as defined 

or measured in an industrial sense. Unlike the continental 

United States, many of these islands are so small that 

forests are integrated across their landscapes and cannot 

be isolated to a geographic “region” where social and 

economic activities can be analyzed specifically in regard 

to their relation to forest resources. And, finally, the 

ubiquitous lack of data that challenges our reporting in the 

other criteria is evident in Criterion 6 as well. As a result, 

with the exception of certain statistics for Hawaii and 

Puerto Rico, there is little or no specific information as to 

the production and trade of forest products, forest-sector 

investment, forest-based recreation, or the economic and 

social well-being of forest-dependent communities.

So, although the socioeconomic dimensions of forests 

are every bit as important in this island context as in the 

continental United States, the measures for describing this 

importance are less defined and developed. As a result, in 

addressing Criterion 6 for these tropical island jurisdictions, we take a more flexible approach than in previous 

criteria, treating each of the criterion’s five subcriteria, 

using available data to say what we can but not reporting 

out on each indicator. For several of the subcriteria there 

is very little information to provide, and in these cases we 

briefly describe why each subcriterion is important and 

identify what sorts of data would be helpful if available. 

In other cases, owing to the nature of small island geographies, we have supplied additional information not 

called for in the MP C&I. In particular, we have included 

a discussion of demographic information on population 

density and growth. 

Criterion Summary

When considering the social and economic dimensions of 

forest sustainability for the islands treated in this report, 

the most important characteristic to bear in mind is the 

high variability in social and economic circumstances 

found between them. Cultural roots and specific histories 

radically differ between regions and islands. Economic 

conditions vary, ranging from high-income jurisdictions comparable to the U.S. mainland to lower income 

jurisdictions that have more in common with developing 

nations. Income sources likewise differ, with high reliance 

on exports and expatriate remittances in some places, 

tourism in others, and diverse activities commensurate 

with developed, large-scale economies in yet others. 

Governmental arrangements also differ, ranging from full 

U.S. statehood to compacts of free association, and these 

arrangements drive differences in economic practices and 
II–66 Assessing Forest Sustainability in the Tropical Forests of the United States

institutions as well as the resources available for forest 

management. All these differences are reinforced by the 

relative isolation imposed by island geography, whose 

effects in the social and economic realms are analogous to 

those imposed in the ecological realm.

Overall, there are few hard data on the social and 

economic dimensions of forest sustainability for the 

islands considered in this report. The general absence of 

commercial wood products industries means that none 

of the traditional economic statistics associated with 

forests, such as production volumes, incomes, and jobs, 

are available. Nonetheless, in many places, the production 

of wooden building and craft materials is identified as 

an important forest contribution. Tourism is the most 

identifiable industry that is at least partially linked to 

forests, but here the statistics are cursory at best and the 

actual role of forests in that industry is not clear. Food 

production, through gathering, hunting, and agroforestry, 

is identified as an essential function of forests, particularly 

in lower income islands, but there is little consistent information on the actual contribution of these activities to 

inhabitant’s welfares. And finally, forests are an important 

source of aesthetic beauty and spiritual sustenance across 

the islands, though these values are difficult to quantify. 

A review of “Statewide Assessments and Resource 

Strategies,” or SWARS) (see chapter 3) produced for 

each of the jurisdictions considered in this report (NASF 

2016) indicates that forest functions are recognized and 

valued as essential contributions to society. The tropical 

islands have deep cultural traditions that have evolved in 

tandem with local ecosystems. This history, combined 

with the isolated character of these places, means that 

residents no doubt have a profound sense of place that is 

strongly linked to local environments, including forests. 

Part of this sense of place involves an understanding of 

the linkages between forests and society, between human 

actions and environmental conditions, which is the hardwon knowledge held by people who have lived in the same 

place for many generations. This knowledge is an important first step in sustainably managing forests, but conditions are changing rapidly in many of these places, and 

management practices will have to adapt to meet these 

changes. On many islands, balancing population growth, 

tourism activity, and general economic development with 

the maintenance of healthy and intact forest ecosystems 

will be an ongoing challenge. On others, managing forest 

resources to meet the material needs of growing populations and providing additional economic opportunities 

where possible will be the major challenge.

Montréal Process Criterion 6 

Subcriteria

The Montréal Process Criterion 6 contains 20 indicators 

arranged under five subcriteria. We address each of these 

subcriteria, but not the individual indicators contained 

within them, in the following sections. Additionally, we 

have included a section on demographic conditions as 

these are often essential in understanding forest sustainability in an island context. Accordingly, the six subcriteria addressed in this chapter are:

• Demographics (not included in MP C&I)

• Production, consumption, and trade (of forest products, 

including nontimber products)

• Investment in the forest sector

• Employment and community needs

• Recreation and tourism

• Cultural, social, and spiritual needs and values

Given the close linkage between human populations 

and ecological conditions throughout the islands, basic 

demographic information provides an essential context 

for understanding forest sustainability. Table C6-1 shows 

basic demographic information (current population, 

population growth trends and densities, and per capita 

incomes) for the Caribbean Islands, Hawaii, and the other 

Pacific Islands. 

The diversity of data sources in table C6-1 points to 

the lack of consistency in data reporting for the island 

jurisdictions. Population growth and gross domestic 

product per capita figures are particularly problematic, 

with variable data sources, reporting dates, and estimation 

techniques. Also, smaller jurisdictions may be subject to 

abrupt changes owing not only to changing conditions 

but also reporting conventions and immigration laws. 

The Commonwealth of the Northern Mariana Islands 

(CNMI) is a case in point, where a nonresident contract 

worker program was phased out in 2009 in response to 

U.S. legislation, resulting in the departure of thousands of 

guest workers and closure of the local garment industry.

The data demonstrate the diversity of demographic 

conditions found across the islands. With the exception 

of Hawaii and Puerto Rico, the jurisdictions in our 

sample are quite small both in terms of land area and of 

population, and they all have higher population densities 

than listed for the continental United States. Common 

sense tells us that population density will be strongly 

linked to forest sustainability, but the density numbers 

should be interpreted with caution. Several places listed 

in table C6-1 are actually comprised of numerous small 
Assessing Forest Sustainability in the Tropical Forests of the United States II–67

Table C6-1. Demographic information for islands considered in this report

Population

GDP per 

capita (2013)c Land area In 2010a Growth from 

2000 to 2010b Per square kilometer

Square 

kilometers Number Percent Number U.S. dollars

Caribbean:

 U.S. Virgin Islands (USVI) 346 106,405 -2.0 308 36,100

 Puerto Rico (PR) 8,870 3,725,789 -2.3 420 28,500

Pacific:

 Hawaii (HI) 16,635 1,360,301 12.6 82 44,024

 American Samoa (AS) 199 55,519 -3.1 279 13,000

 Guam 544 159,358 2.9 293 30,500

 Marshall Islands (RMI) 181 69,747 16.6 385 3,400

 Micronesia (FSM) 702 102,843 -3.7 151 3,100

 Northern Marianas (CNMI) 464 53,883 -22.2 116 13,300

 Palau 459 21,108 3.4 46 13,600

United States 9.8 million 309 million 9.7 32 53,600

a

 USVI, PR, HI, AS, CNMI, Guam, United States = U.S. Census; RMI, FSM, Palau = CIA World Factbook 2014 estimates.

b

 USVI, PR, HI, AS, CNMI, Guam, United States = U.S. Census; RMI, FSM, Palau = estimated from data from Statistics for Development 

(SDD) (http://www.spc.int/sdd/index.php).

c

 CIA World Factbook (except Hawaii, which was calculated using state gross domestic product (GDP) and population—may not be 

directly comparable with other jurisdictions).

Sources: U.S. Census, CIA World Factbook, SDD.

islands (notably the CNMI, Federated States of Micronesia [FSM], Palau, and Republic of the Marshall Islands 

[RMI]), and densities will not be distributed evenly, 

particularly given the high number of uninhabited islands 

in many jurisdictions. Except for the FSM, the percentage 

of total population living in urban areas (as defined by the 

CIA World Factbook, https://www.cia.gov/library/publications/the-world-factbook/) is well in excess of 70 percent, 

and the process of urbanization is continuing everywhere, 

meaning that the populations, and many of their impacts, 

are concentrated primarily in urban centers. The dominant 

role of Honolulu in Hawaii is an example of this. 

Urbanization brings altered relationships between people 

and forests; in some cases reducing direct pressures on 

forests as rural residents migrate to urban centers, but also 

resulting in some forest loss, from conversion to development and timber consumption for building materials, 

for example. Additional effects occur when urbanization 

expands in an unplanned or haphazard fashion across the 

landscape, fragmenting forests and other natural areas, 

a situation that is common in the tropical island jurisdictions considered here. In any case, the influence of population density and urbanization on forest sustainability, 

both in the tropical context studied here and elsewhere, is 

a complex issue (Nowak and Walton 2005, van den Berg 

et al. 2007). Also, with the exception of Puerto Rico and 

Hawaii, the populations listed here are relatively small, 

and although they might be considered predominantly 

“urban” by definition, the towns are necessarily quite 

small relative to the urban centers found in the continental 

United States and often retain a strong rural character. 

Concern over the loss of forest cover and associated forest 

values resulting from development is a common theme 

in the related literature and the SWARS reports (this was 

particularly so in Guam, which has been anticipating a 

marked increase in U.S. military presence through base 

expansions). 

Population growth is likewise variable across the places 

described in table C6-1. Four jurisdictions exhibited 

negative population growth between 2000 and 2010. Of 
II–68 Assessing Forest Sustainability in the Tropical Forests of the United States

the rest, the RMI, and, to a lesser extent Hawaii, stand out 

as high-growth locales. Moreover, most of the jurisdictions (notably Palau and the RMI) had seen substantially 

higher growth rates prior to 2000. However, the growth 

figures presented here may be at least partially an artifact 

of reporting and estimation techniques, particularly for 

those jurisdictions not covered by the U.S. Census (the 

RMI, FSM, and Palau).

It is tempting to equate high population growth with 

growing threats to forest sustainability, but this determination can only be made while considering other 

important social and environmental factors. While the 

high growth rates in the RMI, as well as the high population densities in Puerto Rico, the U.S. Virgin Islands 

(USVI), American Samoa, Guam, and the RMI are not by 

themselves indicators for major concern regarding forest 

sustainability, they should be monitored alongside other 

key data to determine their effects on forests in the future. 

High population growth and density in a limited geographic space will undoubtedly present major challenges 

for forest sustainability if they continue in the long term. 

Moreover, in places such as the USVI or Hawaii where 

tourism significantly increases the number and impact 

of people present at any given time, resident population 

levels and their growth will underestimate actual population pressure for development and local demand for 

environmental services.

The final column in table C6-1 shows per-capita income, 

and here again the conditions differ greatly throughout 

the islands. Hawaii, which is fully incorporated into the 

U.S. economy and political system, enjoys income levels 

similar to those of the other 50 states. The USVI, Guam, 

and Puerto Rico occupy a middle income range, and the 

remaining islands show annual incomes ranging from 

$3,000 to $13,000, a fraction of those generated in the 

50 U.S. states. 

The relationship between income and sustainability is a 

complex one. In general, rising incomes are associated 

with negative environmental effects at the lower end 

of the income scale but may result in reduced negative 

effects (at least locally) at the higher end of the scale as 

residents gain more wealth and security and are able to 

“afford” more environmental protection or management 

of ecosystems (Bhattarai and Hammig 2001, Dinda 2004). 

The extent to which this sort of dynamic is working in any 

of the places considered here, however, will depend on 

specific local conditions, the ways in which subsistence 

and agricultural activities interact with local ecosystems, 

and the economic activities that are driving development. 

Economic growth from timber harvest or agricultural 

activity for export, for example, will have radically different effects on the environment than growth from tourism 

development. In other words, forests and their sustainability will be determined by actual management and use 

and not simply by general levels of economic activity or 

development (Cropper and Griffiths 1994).

Production, Consumption, and 

Trade of Forest Products

When considering production, consumption, and trade 

of forest products, we immediately run into the lack of 

data that also challenges much of our forest sustainability 

reporting for the other criteria. Outside of Hawaii, there 

is very little commercial production of wood products 

for export or sale through formal distribution channels. 

None of the islands reported significant harvests of 

industrial roundwood or fuelwood in the most recent 

report of the Food and Agriculture Organizations Global 

Forest Resource Assessment (FAO 2015). Likewise, in the 

recent round of area forest assessments undertaken in the 

SWARS reporting exercise, the promotion of industrial 

wood products is not mentioned as a central objective for 

forest management in any of the area reports.

However, the lack of both data and a stated focus on 

industrial-scale wood products production notwithstanding, there is a great deal of informal production of 

both wood and nonwood products for local use on many 

islands, some of which may be sold in local markets but 

much of which is for subsistence use or barter trade. 

Although little or none of this activity is measured in 

terms of formal economic statistics of production and 

trade, its role in providing sustenance and other benefits 

for local residents can be crucial and has been documented in a few case studies that provide valuation of 

forest products such as mangrove crabs, wild pig meat, 

crops, and timber in the subsistence economy (Drew et 

al. 2005, Naylor and Drew 1998). Asian Development 

Bank reports for the lower income islands show that 

agroforest-related production is important in household 

production. For example, copra production, handicrafts, 

and “subsistence” use were found to comprise 54 percent 

of household production in the RMI (Asian Development 

Bank 2005). With the exception of copra, none of these 

products are explicitly delineated in production statistics.

Table C6-2 lists products emphasized or otherwise 

mentioned in the SWARS reports and in other literature 

covering the islands considered in this report. The lists are 

not exhaustive—no doubt many uses are not included—

but they do provide a gauge of the relative emphasis that 
Assessing Forest Sustainability in the Tropical Forests of the United States II–69

different outputs are given in different places. Though 

commercial production of forest products is noted for 

several islands, it is very limited and nowhere rises to 

the economic importance of major activities such as, 

for example, tourism or fishing. Rather, wood products 

production for export, where it is considered, is seen as 

a limited opportunity for additional income. This is in 

keeping with the fact that forestry is an extensive land 

use activity, and land is precisely the commodity that the 

islands have in short supply. Those islands reporting commercial production or an interest in production are either 

the larger islands (Hawaii and Puerto Rico), or smaller 

entities with lower population densities (FSM and Palau). 

Table C6-2. Forest products production and use

Wood products Nonwood products

Caribbean:

 U.S. Virgin Islands Mahogany (Swietenia spp.) and tibet (Albizia 

lebbeck) for craft and building materials The last 

reported data from 1997 indicated approximate 

production of 189,000 board feet per year. (The 

Nature Conservancy 2003, see also Pierce and 

Hultgren 1997). 

Food (tropical fruits) and medicinals

 Puerto Rico Limited plantation activity for timber production 

and forest restoration. Some timber production 

for local use, craft, and specialty products (musical 

instruments) (Brandeis et al. 2007, Kicliter 1997)

Agroforestry, food and medicinals, craft 

materials, resins, and oils

Pacific:

 Hawaii Craft and furniture production using native 

hardwoods; small volumes of pulp production 

using nonnative species (eucalypts)

Game animals for personal use; plant 

materials for traditional craft use; edible 

and medicinal plants and fungi for 

traditional and commercial use

 American Samoa Building materials for local use, fuelwood, wood 

for craft production (no formal sector)

Subsistence harvest of food and 

medicinals, craft materials, traditional 

agroforestry systems

 Republic of the Marshall 

 Islands

Wood for craft production Extensive agroforestry and coconut 

plantations; coconut and pandanus 

fiber for craft production

 Federated States of

 Micronesia

Sawnwood production for domestic consumption 

and limited export. Mangrove wood for 

woodcarving

Agroforestry systems

 Commonwealth of the

 Northern Mariana Islands

Fuel, fiber, lumber, and poles for local use Agroforestry systems, medicinals and 

foodstuffs, game animals as important 

traditional source of protein (though 

increasingly scarce)

 Guam None identified Game animals (wild pig and deer) for 

personal use; gathering of betel nuts

 Republic of Palau Building materials for local use, fuelwood, 

mahogany (Swietenia spp.) wood for carved 

storyboards

Agroforestry systems, medicinals, 

foodstuffs, craft materials, and other 

cultural resources

Note: Products are culled from various publications, and the listing here likely does not include all products and uses. 

Source: Statewide Assessments and Resource Strategies reports and miscellaneous. 

Wood products production for local consumption is much 

more common, with local-use building materials listed for 

more isolated and less affluent islands, and wood for crafts 

listed throughout the SWARS reports. Craft products can 

be used in cultural applications or as a source of additional income associated with the tourist trade. Fuelwood 

is another important use in some places, especially as 

required for “imu” (pit oven) cooking of traditional foods, 

still common in the Pacific.

Nontimber forest products such as foodstuffs, medicinals, 

and craft materials are commonly mentioned, either 

as a source for local subsistence use or as inputs for 

the tourist trade. Wild game, and the role of forests in 
II–70 Assessing Forest Sustainability in the Tropical Forests of the United States

providing habitat for game animals, figures prominently 

in several locations, notably in Guam and the RMI, 

where traditional game species (primarily pigs or deer 

introduced by Micronesians or the Spanish) are reportedly 

in sharp decline owing in part to overhunting and a lack 

of habitat. Finally, agroforestry systems, in which trees 

and food crops are intentionally integrated, are a common 

land use throughout these tropical islands. In the Pacific, 

agroforestry practices have deep roots associated with 

the traditional multistory agroforest, tree fallow, or mulch 

systems carried from island to island by Polynesian and 

Micronesian cultures as they successively colonized the 

region. The SWARS reports for the RMI and FSM place 

particular stress on traditional agroforestry as a means of 

providing food security and improved nutrition for residents, and similar objectives are undoubtedly important 

elsewhere in the region. Awareness is rising that traditional agroforest foods (breadfruit, taro, coconut, banana, 

pandanus, foliage, citrus, and other fruits) provide more 

fiber and vitamins than the highly processed Western 

foods that are commonly imported (white rice and bread, 

canned vegetables, and sweetened drinks). 

In the Caribbean, agroforestry is seldom explicitly 

mentioned in the SWARS and other published literature, 

but small-scale agroforestry home gardens are common, 

and the biological legacy of plantation history in the 

region presents opportunities in the area of, for example, 

copra production (from coconuts), bananas, and especially 

shade-grown coffee in combination with various tree 

species (Borkhataria et al. 2012). The extent to which this 

activity is considered to be forest-based as opposed to 

strictly agricultural will vary from place to place, but in 

many instances it is integral to the question of forest use 

and sustainability (MacFarland et al., in press.)

The area and percentage of forests managed for subsistence uses is essentially synonymous with the extent of 

agroforests in the Pacific (excluding Hawaii), although 

subsistence gathering and some management also takes 

place in mangrove forests (crabs) and upland native 

forests. The extremely high percent of Marshallese land 

managed as agroforest (see table C6-3) reflects the limited 

land base of this atoll nation and the extensive coconut 

plantations that were established after Western colonization.

Data on the extent of agroforest are depend on the vegetation classification systems used; Forest Service vegetation 

surveys in the 1980s specifically mapped a variety of 

agroforest types, including secondary vegetation associated with long-term agroforest management, while current 

maps of American Samoa in particular do not attempt 

to map agroforest separately, instead including agroforest variously within other landcover types (“forest,” 

“agriculture” including coconut plantations, and “urban 

cultivated,” including home tree gardens).

Investment in the Forest Sector

Because little in the way of production forestry is present 

on the islands considered in this report, standard investment activity in forestry (i.e., commercial plantations or 

wood processing facilities) is also largely absent. Specifically, there is little or no quantified data on investment 

Table C6-3. Extent of agroforest in Pacific islands

Island/country Source and year(s) of assessment

Agroforest 

extent

Share of

total forest

Acres Percent

American Samoa 1984 (Cole et al. 1988) 15,510 35

2003 (Donnegan et al. 2004) 0 to 9,000 0–20

Republic of the Marshall Islands 2006–2008 (Donnegan et al. 2011b) 20,000 85

Federated States of Micronesia 1975–1976 (Falanruw et al. 1987a, 

1987b; MacLean et al. 1986; 

Whitesell et al. 1986) 

30,308

25

2005–2006 (Donnegan et al. 2006) 35,655 25

Commonwealth of the Northern 

 Mariana Islands

1976 (Falanruw et al. 1989) 4,488 8

2003 (Donnegan et al. 2011b) 1,313 3

Guam 2002 (Donnegan et al. 2004) 1,921 2

Republic of Palau 1976 (Cole et al. 1987) 2,740 4
Assessing Forest Sustainability in the Tropical Forests of the United States II–71

expenditures or outcomes. At the same time, however, 

many of the islands (Hawaii, Puerto Rico, the USVI, and 

Palau) note in their respective SWARS reports limited 

plantations of mahogany and similar tropical species, 

either as ongoing activity or a legacy of past investments. 

In the Caribbean, many areas experienced severe deforestation in the late 19th and early 20th centuries, owing in 

large part to clearing for agriculture. By the 1930s, efforts 

emerged to reforest less productive (agriculturally) and 

sensitive (e.g., slopes) areas. Plantations of high-value 

species (e.g., mahogany or cedar) and fast-growing species 

(e.g., eucalyptus) were established across the islands. 

Initially, these plantations received sound management 

and investment, but over the years management effort 

has dwindled, and it is highly unlikely that these stands 

will receive significant management investments in the 

future. Nonetheless, the reforested areas have served as 

important vectors for forest restoration in Puerto Rico 

and the USVI. In the Pacific Region, opportunities for 

investment in extensive forestry appear to be much more 

limited (as is the land area, except for Hawaii), and where 

growing trees for commercial production is mentioned, 

it is restricted to relatively small plots and focused on 

the production of specialty woods for high-value export. 

Hawaii is an exception, with plantations of eucalypts 

for pulp production having been established in the past; 

eucalyptus plantations from the 1990s are now beginning 

to be harvested for biofuel, but whether this activity 

emerges as a major end use or motivates new plantings 

remains to be seen. In total, tree plantations of native and 

nonnative species cover nearly 90,000 ac and account for 

almost 6 percent of all forest land in Hawaii, though the 

extent to which these lands receive ongoing management 

investments is unclear.

Investment in wood processing facilities is even less 

apparent. Many of the islands cite small-scale production 

of lumber for local use, though it is likely that this occurs 

with simple equipment (e.g., portable sawmills) and 

minimal investment in processing facilities. The FSM is 

the only place that cites sawmilling as a major concern in 

its SWARS report, and it is mentioned primarily in regard 

to the threat local sawmills pose for forest sustainability. 

However, small but ongoing investment in processing 

capacity is occurring here. In any case, the SWARS 

reports nowhere mention a desire or plans for major 

investments in production forestry, either in plantation 

establishment or production facilities.

Investments in various other facets of forest sustainability, 

on the other hand, do receive considerable attention. The 

need for urban forestry enhancements, investments in 

agroforestry, and the establishment of forest management 

and conservation plans are a common theme throughout 

the SWARS reports and other literature on island forestry. 

Many of the islands have forest management departments, 

educational/research facilities, and functional forest 

management activities, and the SWARS reports, including detailed spatial data of forest extent and conditions, 

represent a considerable investment in forest management 

and sustainability. The fact that these investments often 

occur in places with limited resources and other pressing 

problems testifies both to the importance of forests and 

the desire of local governments and peoples to manage 

them wisely.

Employment and 

Community Needs

In line with the general absence of measurable production 

forestry for processing and export, there is little evidence 

that commercial logging or wood products production 

play an important role in the overall economic landscape 

of the islands considered in this report. Certainly in some 

instances, such as the sawmilling activity noted in the 

FSM, the eucalypt harvests in Hawaii, or the mahogany 

plantations in Palau, forestry and wood products provide 

direct formal employment, but the overall dependency of 

island economies on these activities appears to be quite 

small. 

At the same time, however, the various forest outputs 

listed in the previous section point to a level of dependence on forests for local sustenance and well-being in 

island communities that is rare in the continental United 

States. For rural communities, forests are fully integrated 

into daily life, and, in urban settings, the maintenance 

of urban forest resources is a common theme throughout 

the SWARS reports. Add to this the tight feedback loop 

between forest conditions and those of other island ecosystems, and it is clear that forest health and sustainability 

are of crucial importance to local communities and their 

inhabitants. In particular, relationships among forestry, 

agroforestry, and agriculture form an essential link in 

the socioecological systems that feed many islanders, 

especially in the more isolated islands in the Pacific 

region. And finally, forests provide important amenities 

(and outputs) that support tourism, an important source of 

external income in many of the places considered here. 

Beyond these broad statements of the role of forests 

in local lives, the challenge is to find concrete data 

describing the specific linkages between forests and 

communities, and, in this regard, there is very little in 

the way of quantified information to show. Employment 
II–72 Assessing Forest Sustainability in the Tropical Forests of the United States

and income statistics for forest-specific activities, for 

example, are essentially nonexistent. Nonetheless, the 

per capita income data presented above can provide some 

general indications about the relationship between forests 

and local peoples. In the lower income places, where 

available money is not sufficient to import many of the 

items needed on a daily basis, we can assume importance 

of local forests in supplying food, building materials, and 

other subsistence goods to be relatively high. In higher 

income locations, forests may play a lesser role in supplying daily needs but may be an important component 

in generating income from, say, tourism or the export 

of agricultural products. With the exception of Hawaii, 

incomes are significantly lower than in the continental 

United States. In this setting, the sustainable management 

of forests for the benefit of local people clearly will help 

determine the long-term viability of island ecosystems 

and the survival of their inhabitants.

Recreation and Tourism

Although recreation and tourism are lumped together in 

the MP C&I, these two categories represent often fundamentally different activities with fundamentally different 

economic and social implications. This is especially true 

for the islands considered in this report, where tourists 

usually come from great distances, the amount of money 

they spend is an essential income source for many island 

communities, and the sorts of places they go and activities 

they engage in are separate from those of local residents. 

In fact, for most of the places here included, tourism is 

identified as the major industry and income source. Before 

turning to tourism and its relationship to forests, however, 

we will take time to address the question of local recreation.

Local Recreation

Local recreation refers to time spent and activities 

undertaken in the forest by local residents for personal 

enjoyment. Recreation can include activities ranging from 

hunting or mountain climbing to simply taking a walk 

in the woods. Unfortunately, with the exception of the El 

Yunque National Forest in Puerto Rico and a few state 

forests, once again there are no consistent data measuring 

recreation use for the islands considered here. However, 

owing to their relatively rural settings and the closeness 

of their residents to traditional rural lifestyles, we can 

assume that recreation use, both in and outside the forest, 

is considerable.

The preceding section on forest products outlines the 

various uses and noncommercial products obtained by 

local residents from their forests. These uses are commonly considered under the heading of “subsistence,” a 

concept denoting work as much as play. But subsistence 

has a deeper connotation than simply gathering food or 

materials for daily needs. In addition to providing direct 

and tangible benefits to local residents, subsistence is 

often seen as a central component in many rural lifestyles, 

with strong links to local cultural traditions and fostering 

strong, even spiritual, connections between people and 

their natural environment (Emery and Pierce 2005). In 

this context, subsistence is similar to recreation, but it 

also includes aspects of economic dependence as well as 

cultural and spiritual values. It no doubt plays an important role in the lives of many residents, particularly those 

of limited incomes or those living more traditional rural 

lifestyles, but just how large a role is unclear. Though 

information on the harvest of nonwood forest products is 

included in the Criterion 2 chapter in this report, the available information is not equal to the importance of this 

topic. Finally, hunting, particularly for nonnative species 

(feral pigs and deer), is an important subsistence/recreation activity in several Pacific islands, and this points to 

the effects of long-term ecosystem change on local culture 

and the complexity of defining desirable conditions to be 

pursued through forest management and restoration.

Tourism

As opposed to recreation, tourism in the islands is a 

business, often a big one that contributes significantly to 

the gross domestic product. Visitor arrival rates are given 

in table C6-4. For many of the islands, arrivals are well in 

excess of the local population (though, of course, the visits 

often last only a few days), and visitors may comprise a 

majority of the total population present in certain locales 

at any given time. The relative importance of tourism, 

however, varies considerably across the islands, ranging 

from major tourist destinations such as Hawaii or Guam 

to less frequented places, where tourist activity may be 

sought but is much less developed. In the former, tourism 

is the number-one industry, generating incomes that 

dwarf all other sources. The Guam Visitor Bureau, for 

example, estimates that tourism accounts for 60 percent 

of the country’s major income sources. The FSM, on the 

other hand, has a limited number of visitor arrivals and 

stresses its “unspoiled” character while actively seeking 

ecotourism development. At between 5,000 and 10,000 

visitors per year, the RMI has the lowest visitation rate, 

equivalent to just 9 percent of the population as opposed 

to 400- to 700-percent levels for the major destinations 

such as Hawaii or Guam.
Assessing Forest Sustainability in the Tropical Forests of the United States II–73

There is a strong correlation between country visitation 

rates and per-capita income (as shown in table C6-1), and 

high tourism activity no doubt plays a role in boosting 

local incomes, though the actual relationship between 

these variables is more complex than a simple one-way 

formula in which more tourism produces more income—

higher income islands, for example, may be more successful at attracting tourists in the first place. 

Following their rapid expansion in the 1980s and 1990s, 

visitation rates appear to have leveled off or even declined 

over the last decade (note the sharp drop in American 

Samoa, for example). Major recessions that began in the 

early 1990s in Japan and in 2008 in the United States, as 

well as sharply increasing airfares, are likely responsible 

for a large proportion of these observed declines. Whether 

visitation rates have stabilized or will return to a growth 

trajectory when the global economy fully recovers is an 

open question. The answer will have important implications for forest sustainability, as it is much easier to adjust 

in a stable environment than in one characterized by continued rapid growth in visitation. In the poorer locations, 

however, persistent poverty and the failure of tourism to 

help boost local incomes may also have negative impacts 

in regards to sustainability.

Tourism affects local societies and ecologies in different 

ways. On the positive side, it constitutes a substantial 

opportunity to garner income without directly exploiting or depleting local resources. As a result, it is often 

presented as a relatively sustainable form of development 

in an island setting, as compared to more resource-intensive forms such as logging or mining. Nonetheless, tourist 

infrastructure developments, such as airports, cruise ship 

landings, and hotels, have various and direct environmental consequences. Likewise, the effect of large concentrations of visitors in a limited space can have numerous 

negative impacts both to the environment and to the host 

society, impacts ranging from waste and sewage generation to the social and economic impacts that arise when 

local communities become “overrun” by visitors and the 

businesses that cater to them. 

As regards forests in particular, significant impacts of 

tourism include (1) the effects of onsite activity such as 

soil erosion and compaction, human-wildlife interactions, 

littering, and general crowding affecting the natural 

character of the setting; and (2) effects from infrastructure 

development such as forest fragmentation and conversion, 

introduction of nonnative species, and changing hydrological properties as forest cover is replaced by impermeable 

surfaces. At the same time, however, tourism provides 

economic opportunities that directly or indirectly rely on 

the maintenance of local environmental quality, including 

the quality of forests. Upland and mangrove forests provide tourist opportunities in hiking, waterfall visits, and 

novel boat tours; forests provide background scenery and 

watershed protection that enhance the experience of tourists focused mainly on beaches and oceans. The relationship between tourism income and environmental quality 

Table C6-4. Visitor arrivals, 2000–2010

2000 2005 2010

2010 as 

percentage 

of population Notes

- - - - - - - Thousands - - - - - - - Percent

Caribbean:

 U.S. Virgin Islands 546 593 590 464

 Puerto Rico 3,300 3,700 3,100 83 Air arrivals only

Pacific:

 Hawaii 6,900 7,000 9,900 728 Air arrivals only

 American Samoa 44 24 23 41

 Republic of the Marshall Islands 5 9 5 7 Air only (2005 air and sea)

 Federated States of Micronesia 21 19 45 44

 Commonwealth of the Northern Mariana Islands 517 498 375 696 Air arrivals only

 Guam 1,300 1,200 1,200 753

 Republic of Palau 58 81 86 407 Air arrivals only

Note: Cruise ship visitations are omitted for five of the nine countries listed in the table. In comparison to air arrivals, cruise ship 

activity usually generates less local income, but will also have fewer negative environmental impacts. However, the decisions by 

major cruise operators to visit, or not to visit, a given port of call can have major consequences for local communities, with abrupt 

shifts in conditions resulting in the need for rapid adaptation.

Source: United Nations, UNData (http://data.un.org/Default.aspx). Hawaii Tourism Authority (for Hawaii only). 
II–74 Assessing Forest Sustainability in the Tropical Forests of the United States

is one area in which sustainable resource management and 

tangible economic benefits in the form of hard cash can 

be explicitly linked. This linkage can foster considerable 

political support for forest sustainability efforts.

The SWARS reports for the islands considered here 

reflect this ambiguous relationship between tourism and 

forest sustainability. The desire to preserve and enhance 

forest resources as a means of supporting tourism activity 

is a common theme running throughout the SWARS 

reports, but the need to manage tourism and mitigate its 

potential negative impacts is also noted in many places in 

the reports and is incorporated in specific management 

prescriptions. Particularly in places that have already 

experienced substantial tourism development, the need 

to manage tourism activity, both from an environmental 

standpoint and a social standpoint, is well recognized. 

Finding a good balance between generating local incomes 

and managing the complex effects tourism entails, 

however, will be an ongoing challenge.

Cultural, Social, and Spiritual 

Needs and Values

The MP C&I contain two indicators in this subcriterion: 

(1) “Area and percentage of forests managed primarily 

to protect the range of cultural, social, and spiritual 

needs and values;” and (2) “The importance of forests to 

people.” The values measured in this subcriterion are of 

crucial importance, but measuring them in a concise and 

replicated fashion is extremely difficult.

A major challenge in reporting out in the national report 

(USDA FS 2011) for the first indicator identified above 

arises from the fact that most public forests in the United 

States are managed for multiple objectives, among them 

the sorts of values included in this indicator. Designated 

wilderness, for example, may help address people’s 

spiritual need for wild places, but it is also designed 

to preserve habitats or provide backcountry recreation 

opportunities. The same challenge applies to measuring 

the cultural, social, and spiritual contribution of forests 

in the tropics. In addressing forests on the mainland, 

the national report simply presents information on the 

amount of forest in various protected statuses, with 

special emphasis on public lands—a reasonable approach 

because private lands are generally not subject to the 

same legal protections (although land trusts and conservation easements constitute an important exception). The 

same approach can be applied to the islands considered 

in this report. Indicator 1 and 2 in Criterion 1 provide 

information about forest ownership and protected status 

(see Criterion 1 chapter). Hawaii exhibits the highest 

proportion of forest land in public ownership (53 percent) 

and formally protected status (43 percent). Guam has 

high public ownership but an extremely low proportion 

of formally protected forest land. The remaining islands 

either have relatively low levels of public ownership and 

protected status or lack available data to address the 

question.

In addressing the second indicator, “the importance of 

forests to people,” the national report relied on response 

data from focus groups, an approach that was not practical 

for this report. Although we have few data directly linked 

to this question, much of the information in the foregoing 

sections and chapters help flesh out the various ways in 

which tropical forests are important to island inhabitants. 

These range from direct sustenance through subsistence 

gathering to support for commercial economic activity, 

notably tourism. Likewise, the aesthetic and spiritual 

values associated with forest environments on the islands 

provides residents and visitors with substantial benefits 

on a daily basis. The fact that we have little quantified 

information to measure the magnitude of these values in 

no way indicates a lack of importance.

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Lake, F.; Zamora, D. [In press]. Human dimensions 

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Bentrup, G.; Patel-Weynand, T., eds. Agroforestry: 

enhancing resiliency in U.S. agricultural landscapes 

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MacLean, C.D.; Cole, T.G.; Whitesell, C.D.; Falanruw, 

M.C.; Ambacher, A.H. 1986. Vegetation survey of 

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(2000–2050) and its estimated impact on the US forest 

resource. Journal of Forestry. 103(8): 383–389.

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the U.S. Virgin Islands: an overview of trends in forest 

products use. St. Croix, U.S. Virgin Islands: Virgin 

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Council. 31 p.

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of pre-European deforestation on Pacific islands. 

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[USDA FS]. 2011. National report on sustainable 

forests—2010. FS-979. Washington, DC: U.S. 

Department of Agriculture, Forest Service. 212 p. 

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2016).

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FS]. 2014. Draft forest plan assessment, El Yunque 

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DOCUMENTS/stelprd3794279.pdf. (September 2016).

van den Berg, A.E.; Hartig, T.; Staats, H. 2007. 

Preference for nature in urbanized societies: stress, 

restoration, and the pursuit of sustainability. Journal 

of Social Issues. 63(1): 79–96.

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Trust Territory of the Pacific Islands. In: Carpenter, 

R.A., ed. Assessing tropical forest lands: their 

suitability for sustainable uses. Proceedings of 

conference on forest land assessment and management 

for sustainable uses. Dublin, Ireland: Tycooly 

International: 330–334.

Whitesell, C.D.; MacLean, C.D.; Falanruw, M.C.; 

Cole, T.G.; Ambacher, A.H. 1986. Vegetation 

survey of Kosrae, Federated States of Micronesia. 

Resour. Bull. PSW‐17. Albany, CA: U.S. Department 

of Agriculture, Forest Service, Pacific Southwest 

Research Station. 8 p.

A community meeting as part of an adaptive management project encouraging municipalities to manage their mangrove 

crab resources. The crabs (Scylla serrata) were found to be the most economically valuable product of mangrove forests in 

Kosrae, Federated States of Micronesia.

Kathleen Friday
Assessing Forest Sustainability in the Tropical Forests of the United States II–79

Criterion 7

Assessing Forest Sustainability in the Tropical Forests of the United States

Legal, Institutional, and Economic Framework for 

Forest Conservation and Sustainable Management

Guy C. Robertson and Kathleen S. Friday

Introduction

The Montréal Process Criterion 7, which addresses the 

institutional, legal, and economic frameworks needed 

to support sustainable forest management, is the final 

criterion in the Montréal Process Criteria and Indicators 

and the last to be considered in this report. Understanding 

the nature and status of these frameworks is an essential 

part of any assessment of forest sustainability, and it is 

doubly important because the laws, policies, and institutions governing forest management are directly under our 

control as a society. These are the tools we use to effect 

forest sustainability. 

However, policies and institutions are extremely difficult 

to characterize concisely. Criterion 7 has proven to be one 

of the most difficult criteria to address in the National 

Report on Sustainable Forests (USDA FS 2011). Moreover, when extending this criterion to the U.S. tropics, 

there is little in the way of consistent datasets covering 

these topics for the island jurisdictions considered in this 

report. As a result, instead of addressing each of the indicators in a separate section, this chapter provides a narrative description of the institutions and activities affecting 

forest management in the islands. A general summary of 

Criterion 7 is followed by a look at (1) local government 

institutions; (2) academic institutions; (3) nongovernmental organizations; (4) the engagement of island entities 

with the U.S. federal government, notably the U.S. Forest 

Service; and (5) regional collaborative efforts. Land 

tenure and the rights of indigenous peoples to forest 

access and use are crucial concerns that are addressed 

in the section covering local government. Although this 

treatment may not approach the comprehensive assessment of institutions envisioned by the Montréal Process, it 

does provide a compendium of reference information and 

a discussion of local capacities for conducting sustainable 

forest management.

Criterion Summary

The heterogeneity that characterizes ecological and social 

conditions in the islands is equally evident in their institutional, legal, and economic arrangements. Part of this 

stems from the varying degrees of association the islands 

have with the United States, ranging from statehood 

(Hawaii) to commonwealth or territorial status (Commonwealth of the Northern Mariana Islands [CNMI), American Samoa [AS], Guam, Puerto Rico, and the U.S. Virgin 

Islands [USVI]) to independent countries in compacts of 

free association with the United States (Federated States 

of Micronesia [FSM], Republic of the Marshall Islands 

[RMI], and Republic of Palau). But much of the difference 

results from different economic and social conditions, 

simple geography, and the histories and traditions unique 

to each of the islands. Total populations and economies 

are small relative to the U.S. mainland (see table C6-1 in 

Criterion 6). Institutions, like many businesses, are subject to economies of scale, and many of the islands lack 

the depth and breadth of institutional support for forestry 

that may be taken for granted in the contiguous United 

States. Likewise, the contiguous states are served by many 

national programs that do not fully extend to the islands 

for reasons of political status, program scope, or travel 

expense, leaving these smaller island economies without 

the benefits of those programs and without sufficient local 

resources to conduct equivalent programs locally. Even 

if funding is offered at a generous level on a per-capita 

or per-acre basis, total funding may be insufficient to 

replicate national program functions, or small local staffs 

without required specialists may be unable to fully utilize 

or qualify for a given funding opportunity. 

The islands do benefit, however, from collaboration with 

their neighbors to address similar challenges, and from 

the activities of dedicated individuals interested in sustaining forests. And they actively seek engagement from 

U.S. federal agencies and non-U.S. entities such as the 

Secretariat of the Pacific Community (SPC). The Forest 

Service, for example, inventories island forest resources 

through its Forest Inventory and Analysis (FIA) program; 

provides assistance in inter-island collaboration and 

on-the-ground project implementation through its State 

and Private Forestry division; and undertakes focused 

research on tropical forestry issues through its International Institute of Tropical Forestry, based in Puerto 

Rico, and its Institute of Pacific Islands Forestry, based 

in Hawaii. Many islands, particularly in the Pacific, may 

also benefit from a strong “community infrastructure” 

based on a history of communal ownership and resource 
II–80 Assessing Forest Sustainability in the Tropical Forests of the United States

management, something that is difficult to gauge from 

official documents but is an extremely valuable institutional resource nonetheless. The overlap of traditional 

or communal land management systems with Western 

ownership and management systems based on private 

and public property distinctions have resulted in checks 

and balances, and some novel, complex strategies in the 

Pacific. Depending on their political status in relation to 

certain international agencies, the Pacific freely associated 

states benefit from international funding sources which 

are unavailable to the state of Hawaii, the territories, and 

the commonwealths.

Montréal Process Criterion 7 

Indicators

Recognizing the challenges presented by Criterion 7, in 

2009 the Montréal Process Working Group revised the 

criterion, reducing the number of indicators from 20 to 10 

and reformulating the remaining indicators, making them 

more concise, streamlined, and measurable than previous 

versions (Montréal Process 2015). The resulting indicator 

set covers topics ranging from forest policy to public 

participation to research and monitoring activities. For 

reference, the 10 Montréal Process Criterion 7 indicators 

are (in abbreviated form):

• 7.45: Legislation and polices supporting the 

sustainable management of forests

• 7.46: Cross-sectoral policy and program coordination

• 7.47: Taxation and other economic strategies that 

affect the sustainable management of forests

• 7.48: Clarity and security of land and resource 

tenure and property rights

• 7.49: Enforcement of laws related to forests

• 7.50: Programs, services and other resources 

supporting the sustainable management of forests

• 7.51: Development and application of research 

and technologies for the sustainable management 

of forests

• 7.52: Partnerships to support the sustainable 

management of forests

• 7.53: Public participation and conflict resolution in 

forest-related decision making

• 7.54: Monitoring, assessment and reporting on 

progress towards sustainable management of forests

However, owing to a lack of data combined with the 

heterogeneity of the island jurisdictions and the challenges 

associated with reporting out on each indicator for each 

jurisdiction separately, we have consolidated the Criterion 

7 reporting here into the following categories: (1) local 

government (with an emphasis on land tenure arrangements), (2) academic institutions, (3) nongovernmental 

organizations (NGOs), (4) cooperative activities with the 

U.S. federal government, and (5) regional collaboration. 

Although these categories diverge from the Montréal Process indicators for Criterion 7, they do address specific, 

important metrics associated with the revised set and 

provide a useful framework for describing the institutional setting in which sustainable forest management can 

occur. They also serve as a reference for interested readers 

wishing to identify specific organizations.

Local Government

The Pacific and Caribbean island governments considered 

in this report range from full U.S. statehood, to U.S. 

territories, to “freely associated states” in voluntary 

association with the U.S. government (see table C7-1). 

Each of these relationships carries with it different rights, 

constraints, and institutional arrangements in regards to 

the U.S. Government in general, and the U.S Forest Service in particular. More importantly, the size and nature of 

local government institutions largely determine the ability 

of the islands to actively engage in forest management 

activities and to avail themselves of the various federal 

and international programs available to help in this effort. 

Six of the nine island entities have government units 

explicitly focused on forestry, with the largest (Puerto 

Rico and Hawaii) displaying the greatest capacity and 

range of activities. The absence of explicitly identified, 

locally funded forestry agencies in several of the Pacific 

Islands reflects a lack of resources associated with smaller 

populations and therefore smaller governments, which in 

some cases have a single locally funded “state forester.” It 

also often reflects greater integration of tropical forestry 

with other land management activities such as coastal 

management or agriculture. In 2010, all the island entities 

completed statewide assessments and resource strategy 

reports (SWARS—later called State Forest Action Plans) 

as a prerequisite for participation in Cooperative Forestry 

Assistance Act programs. These reports compile and 

evaluate large amounts of data, and testify to the willingness and capacity of island governments to generate and 

analyze forestry information.

Government and Land Tenure

Land tenure, or the means by which land rights and 

ownership are allocated within a given society, strongly 

determines how forests are managed, who does the 

management, and who benefits from resulting forest 
Assessing Forest Sustainability in the Tropical Forests of the United States II–81

conditions and outputs. Land tenure arrangements in 

the islands considered in this report, particularly in the 

Pacific, include various combinations of traditional tenure 

arrangements and private ownership modeled on U.S. 

legal concepts and practices. All the islands have systems 

in place that identify property and outline the rights associated with that property and its transfer, and they also 

have systems to provide landowners due process relative 

to the loss of property or property rights. Some islands 

have dual systems, with different lands under different 

tenure systems and subject to different processes, including incremental surveying and registration of parcels 

under private ownership.

Formal Relations With the United States

As a state, Hawaii adheres to all U.S. laws concerning 

private property in accordance with the U.S. Constitution. Congress has the power to govern U.S. territories 

and commonwealths, and to make rules for disposing 

of federal property under the Territorial Clause (Article 

4, Section 3) of the U.S. Constitution. The relationship 

differs between each jurisdiction and the United States. 

The Commonwealth of the Northern Mariana Islands, 

Puerto Rico, and the USVI are self-governing according 

to constitutions that are recognized by Congress. Guam 

is governed according to the Guam Organic Act of 1950. 

Each sets forth the specifics of the relationship with the 

United States and the local governing structure, including 

judicial systems to protect property rights. Territorial 

courts established by Congress are available in the CNMI, 

Guam, and the USVI, while Puerto Rico participates in 

the U.S. federal judicial system.

American Samoa is an unincorporated and unorganized 

territory administered by the Bureau of Insular Affairs, 

U.S. Department of the Interior. Although the Territorial 

Clause generally applies, the relationship between the 

United States and AS is further set forth in several Acts of 

Secession and in the AS constitution. It is not part of the 

federal judicial system, nor does it have a territorial court 

set up by Congress. American Samoa’s judiciary was 

Table C7-1. Government institutions responsible for forest management activities in the Pacific and 

Caribbean islands

Jurisdiction Relation to United States Relevant local agency Relevant agency website

Caribbean:

U.S. Virgin Islands Territory Department of Agriculture, 

Forestry Division

http://www.vifresh.com/forestry.php

Puerto Rico Commonwealth Department of Natural and 

Environmental Resources, 

Forest Service Bureau

http://www.drna.gobierno.pr/ 

Pacific:

Hawaii U.S. state  Department of Lands and 

Natural Resources, Division 

of Forestry and Wildlife 

http://hawaii.gov/dlnr/dofaw 

American Samoa Territory American Samoa Environmental Protection Agencyhttp://www.epa.as.gov/ 

Republic of the 

Marshall Islands

Freely associated state  Ministry of Resources and 

Development, Department 

of Agriculture

http://www.rmiembassyus.org/

Government.htma

Federated States of 

Micronesia

Freely associated state Department of Resources and 

Development (delegated to 

each state)

http://www.fsmrd.fm/ 

Commonwealth of the 

Northern Mariana Islands

Commonwealth Department of Lands and 

Natural Resources

http://gov.mp/a

Guam Territory Department of Agriculture, 

Division of Forestry 

http://www.guam.gova

Republic of Palau Freely associated state Ministry of Natural Resources, 

Bureau of Agriculture, Forestry 

Section

http://palaugov.orga

a

 General government website. No agency-specific website available.
II–82 Assessing Forest Sustainability in the Tropical Forests of the United States

initially created and administered by the U.S. Navy, and 

now is operated under the authority of the Secretary of 

the Interior, who appoints the chief justice and associate 

justice. The AS courts can adjudicate property rights and 

conservation-related cases.

The FSM, RMI, and Palau are sovereign nations that have 

entered into compacts of free association with the United 

States. As such, they are guaranteed military protection 

and certain types of financial assistance administered 

through the Office of Insular Affairs or other legislatively 

designated federal agencies.

Traditional Land Tenure Arrangements

At the same time, the Pacific islands, including Hawaii, 

have a long history of self-government that evolved in 

relative isolation over many centuries as part of their Polynesian or Micronesian heritage. The resulting structures 

and practices focus upon, among other things, land use 

and the allocation of scarce island resources, and they 

constitute a different land tenure system than the standard 

public-private system found on the U.S. mainland and the 

U.S. territories in the Caribbean. Moreover, Pacific islands 

have been wary of the sale of lands to outside parties, 

and there are traditional customs in many places that ban 

property sales to keep land in family or local ownership. 

Public or communal ownership and restrictions on transference of land to nonresidents are common. 

In AS, 88.4 percent of the land is “communal,” held under 

a Matai or chiefly system. The Matai, who is generally a 

familial head, has authority over this land and those who 

live and work on it. Property taxes are levied on individuals working familial land in accordance with direction 

from the Matai. Permission must be granted from the 

Matai to clear, plant, or build on communal lands. Permission tends to be granted only for those purposes, however, 

and other management activities (e.g., those associated 

with conservation management) do not constitute grounds 

to apply to a Matai for personal use and management of 

communal land. Leases or other designations on communal land cannot last more than 55 years. For example, 

the National Park of American Samoa encompasses 

13,500 ac across three islands that are leased by the U.S. 

Department of the Interior from the Matai, who maintains 

authority over this land.

The FSM constitution bars any noncitizen or corporation, 

not wholly owned by citizens, from acquiring title to 

land. Most of the native forest land has not been formally 

surveyed, mapped, registered, or titled, but ownership of 

these lands is generally recognized under traditional land 

tenure systems, including traditional overlapping rights 

(akin to easements) and traditional roles of chiefs in land 

allocation and land use decisions. Formal designation and 

management of some forest lands as public property on 

some islands has remained subject to negotiation with 

chiefs or adjacent landowners, and traditional prerogatives 

have largely been recognized in this process. Property 

rights, land ownership, and inheritance follow traditional 

patterns, but some sales between indigenous landowners 

do take place within and outside the government land 

court system. The CNMI constitution likewise provides 

that land can be privately owned only by people of Northern Mariana (Chamorro or Carolinian) descent, but others 

may lease land for up to 55 years. 

In the RMI, nonresidents may not purchase land, and 

individual parcels of land may be owned by multiple 

individuals simultaneously through the country’s complex 

customary land tenure system. Three general forms of 

land tenure occur in Palau: public community tenure, kin 

group tenure, and individual tenure.

Reconciling Western and traditional governance and land 

tenure practices is often a difficult task requiring a certain 

degree of flexibility. The leasing practice described above 

is one approach that seeks to combine traditional structures with modern tenure and management needs (e.g., the 

management of national parks). A sample of other recent 

examples includes:

• Pohnpei (FSM). Some chiefs and municipal leaders 

have incrementally accepted the boundaries of the central “Watershed Reserve” that designates much of Pohnpei’s native forest as pubic property; physical marking 

of the boundary line has proceeded as each community 

has agreed to honor it.1

• Kosrae (FSM): The central, forested uplands were considered government property until a 1995 constitutional 

amendment allowed reclamation by the descendants 

of original landowners. It is significant that, by 2010, 

no certificates of title had in fact been issued for these 

lands.2

• Hawaii: In 2006, the Wao Kele o Puna forest (27,785 

ac) became the property of the Office of Hawaiian 

Affairs (OHA), the acquisition partially funded by the 

Forest Service’s Forest Legacy Program. This forest 

was ceded land (former crown lands) held in trust under 

state ownership until the state sold it to a private estate 

in 1986, triggering major protests. Not only was its 

1 Kostka, W. 2014. Personal communication. Executive 

director, Micronesia Conservation Trust, PO Box 2177, Kolonia, 

Pohnpei, FSM 96941.

2 Charley, B. 2014. Personal communication. Forest Legacy 

Program Manager, Kosrae Island Resource Management 

Authority, PO Box 480, Tofol, Kosrae, FSM 96944.
Assessing Forest Sustainability in the Tropical Forests of the United States II–83

return to public ownership therefore significant, but its 

titling to OHA instead of the state forestry agency represented a new landowning role for OHA and a possibly 

important precedent for the future of ceded forest lands.

These examples involve the transference of lands, back 

and forth, between traditional, public, and private ownership categories, indicating the need for modern and 

traditional systems to accommodate one another. 

In contrast to the Pacific islands, pre-Colombian inhabitants of the Caribbean Islands, including the Caribs, 

Arawaks, Ciboneys, and Tainos, were decimated during 

periods of colonization by European nations, and their 

traditional tenure and land management practices were 

all but lost (Saunders 2005). The islands are today 

inhabited by colonial and post-colonial immigrants and 

the descendants of Africans who were enslaved and 

remained following emancipation. Although indigenous 

groups no longer exist as separate and identifiable races or 

cultures in Puerto Rico or the USVI, many hold significant reverence for their pre-Colombian predecessors, and 

these groups continue to be very important to the islands’ 

culture and identity (See, for example, Maldonado et al. 

1999). Cultural and historical traditions are recognized 

through historical preservation laws, but no property 

rights or land tenure privileges are accorded through 

traditional practices or to any one group to the exclusion 

of others. 

Academic Institutions

Universities, colleges, and community colleges can 

serve as reservoirs of forestry knowledge and expertise, 

as training grounds for future managers, as windows 

on techniques and practices carried out in other places, 

and as focal points for collaborative efforts between 

government, communities, and private-sector entities. 

The academic institutions present on the islands (see table 

C7-2) range considerably in their size and the degrees they 

confer, depending in large part on the size and resources 

of their respective island jurisdictions. Hawaii and Puerto 

Rico, for example, have multiple institutions with programs ranging from associate degrees to full doctorates, 

while the two island jurisdictions with the smallest 

populations, Palau and American Samoa, are restricted 

to community colleges granting associate degrees in 

agriculture and general resource management. Many of 

these institutions appear to have strong concentrations 

in marine and terrestrial resource management relative 

to their other offerings, reflecting local awareness of the 

importance of resource management in island ecologies. 

Universities in Hawaii, Puerto Rico, and Guam often 

serve as hubs, hosting students from other islands in 

their respective regions. 

Seven of the nine jurisdictions host land-grant universities or colleges. (Land grant programs in the remaining 

two, Palau and the RMI, are delivered by the College 

of Micronesia–FSM Land Grant program in affiliation 

with Palau Community College and the College of the 

Marshall Islands.) These institutions receive Hatch 

and Smith-Lever funding for agricultural research and 

extension, respectively, funds which are often used 

for agroforestry-related work in the islands. Also, the 

Renewable Resources Extension Act (RREA) provides 

funding for extension activities related to forestry and 

natural resources at certain land-grant institutions, and 

McIntire-Stennis formula funds may support land-grant 

institutions’ cooperative forestry research programs. 

Qualification and receipt or non-receipt of RREA and 

McIntire-Stennis funds is an indicator of each island’s 

staff capacity and activity in forestry extension and 

research. 

Nongovernmental Organizations

Nongovernmental organizations (NGOs) play a crucial 

role in promoting resource conservation and local 

development needs throughout the islands. They facilitate community participation and act as a link between 

local, national, and international actors, and the resources 

they control. In addition to the organizations listed in 

table C7-3, international NGOs are active throughout 

the Caribbean and Pacific regions. Through its offices 

in Palau and the USVI, The Nature Conservancy has 

conservation programs focused on Micronesia and the 

Caribbean, and, in line with its domestic U.S. focus, 

the Sierra Club maintains offices and local chapters in 

Hawaii and Puerto Rico. 

Cooperative Activities with the 

U.S. Federal Government

Applicable U.S. national laws and regulations protect 

public benefits arising from forests and prevent damage 

to natural resources such as wetlands, water and air 

quality, wildlife, and threatened and endangered species. 

Tax, business, and health and safety laws and regulations 

also affect private forestry, forest-based industries, and 

community stability. Federal regulatory programs affecting private forest lands are administered by agencies 

such as the U.S. Environmental Protection Agency, the 

U.S. Army Corps of Engineers, and the U.S. Fish and 

Wildlife Service. These laws apply in Hawaii and in the 

U.S. territories. Also, certain of these laws, notably the 
II–84 Assessing Forest Sustainability in the Tropical Forests of the United States

Table C7-2. Sample of academic institutions related to forests and forest managementa

Academic institutions Relevant programsb Website

Land-grant 

status and 

programs

Caribbean:

 USVI University of the 

Virgin Islands

M.S. in marine and environmental 

science; minor in environmental 

science

http://www.uvi.edu/default.aspx Land-grant

McIntire-Stennis

RREA

 Puerto 

 Rico

University of Puerto Rico 

at Mayaguez

B.S., M.S. in agricultural sciences and 

M.S. in horticulture

http://www.uprm.edu/portada/ Land-grant

McIntire-Stennis

RREA

University of Puerto Rico at 

Rio Piedras

B.S., M.S., Ph.D in biology (including 

forest ecology) and environmental 

science

http://biology.uprrp.edu/

http://envsci.uprrp.edu/ 

None

Universidad Metropolitana 

School of Environmental 

Affairs 

M.S. in environmental management; 

M.A. in environmental affairs

http://umet.suagm.edu/ None

Universidad Interamericana Environmental planning http://inter.edu/i2/ None

Pacific:

 Hawaii: University of Hawaii at 

Manoa, College of 

Tropical Agriculture 

and Human Resources

B.S., M.S., Ph.D. degrees awarded in 

natural resources management 

and related fields

http://www.ctahr.hawaii.edu/site/ Land-grant

RREA

McIntire-Stennis

University of Hawaii at Hilo M.S. in tropical conservation biology and environmental science; 

forest resource management and 

conservation certificate

http://hilo.hawaii.edu/ None

Hawaii Community 

College

A.S. in tropical forest ecosystem and 

agroforestry management

http://hawaii.hawaii.edu/

forestteam/ 

 None

Windward Community 

College

Certificate of Completion for 

“subtropical urban tree care”

https://windward.hawaii.edu/

academics/Tree_Care_CC/ 

 None

 American 

 Samoa

American Samoa 

Community College

A.S. in agriculture, community and 

natural resources (forestry program 

housed in Division of Community 

and Natural Resources)

http://www.amsamoa.edu/ Land-grant

McIntire-Stennis

 RMI College of Marshall Islands http://www.cmi.edu/ Affiliation with 

COM-FSM

 FSM College of Micronesia–FSM A.S. in agriculture and natural 

resource management

http://www.comfsm.fm/ Land-grant

 CNMI Northern Marianas College A.S. in natural resource management http://www.marianas.edu/ Land-grant

 Guam University of Guam, College 

of Natural and Applied 

Sciences

B.A. in agriculture, biology; 

M.S. in biology, environmental 

sciences

http://www.uog.edu/schools-andcolleges/college-of-natural-andapplied-science/cnas-home 

Land-grant

RREA

McIntire-Stennis

 Palau Palau Community College A.S. in agricultural science http://pcc.palau.edu/ Affiliation with 

COM-FSM

a

 Sample is based on authors’ knowledge, Web search, and reviewer response. Some institutions are not listed.

b

 Degree titles are approximate. A.S. = Associate in Science.

USVI = U.S. Virgin Islands; RREA = Renewable Resources Extension Act; RMI = Republic of the Marshall Islands; 

FSM = Federated States of Micronesia; CNMI = Commonwealth of the Northern Mariana Islands. 

Source: Hollyer, J. 2008. An inventory of federal agriculturally related programs in the Pacific, 2008. Unpublished report. On file 

with: James Hollyer, College of Natural and Applied Sciences, University of Guam, UOG Station, Mangilao, Guam 96923.
Assessing Forest Sustainability in the Tropical Forests of the United States II–85

Table C7-3. Sample of nongovernmental environmental organizationsa

Local, island-based organizations Relevant websites

Caribbean:

Regional The Caribbean Landscape Conservation Cooperative http://caribbeanlcc.org/ 

USVI St. Croix Environmental Association http://stxenvironmental.org/

Trust for Virgin Island Lands http://www.virginislandslandtrust.org/

Virgin Islands Conservation Society http://viconservationsociety.org/

Puerto Rico Caborrojeños Pro Salud y Ambiente http://www.ccpsai.org/web/ 

Ciudadanos del Karso http://www.cdk-pr.org/en/

Fundación Amigos del Yunque http://www.amigosdelyunque.org/

Para la Naturaleza, nonprofit branch of the 

Conservation Trust of Puerto Rico

http://paralanaturaleza.org//

Tropic Ventures http://www.globalecotechnics.com/2012/05/tropicventures-sustainable-forestry-project-in-puerto-rico

Pacific:

Hawaii Hawaiian Islands Land Trust http://www.hilt.org/ 

Hawai‘i Forest Industry Association http://www.hawaiiforest.org/

Natural Resources Council of Hawaii —

The Nature Conservancy, Hawaii Program http://www.nature.org/ourinitiatives/regions/

northamerica/unitedstates/hawaii/index.htm

Trust for Public Land http://www.tpl.org/what-we-do/where-we-work/hawaii

Regional Micronesia Conservation Trust http://www.ourmicronesia.org/ 

Nature Conservancy Micronesia Program http://www.nature.org/ourinitiatives/regions/

asiaandthepacific/micronesia/index.htm

American 

 Samoa

(None found)

RMI Marshall Islands Conservation Society

FSM Chuuk Conservation Society

Conservation Society of Pohnpei 

Kosrae Conservation and Safety Organization

Yap Community Action Program

Yap Institute of Natural Science

Yela Environmental Landowners’ 

Authority Kosrae)

—

http://www.serehd.org/ 

http://kosraeconservation.blogspot.com/

—

https://www.facebook.com/pages/Yap-Institute-ofNatural-Science/149847135051994

 —

CNMI Micronesia Islands Nature Alliance http://www.minapacific.org/ 

Guam Guam Environmental Alliance https://sites.google.com/site/guamenvironmentalalliance/ 

Palau Palau Conservation Society http://www.palauconservation.org/cms/index.php 

a Sample is based on authors’ knowledge, Web search, and reviewer input. Not all organizations are included. USVI = U.S. Virgin Islands; 

RMI = Republic of the Marshall Islands; FSM = Federated States of Micronesia; CNMI = Commonwealth of the Northern Mariana Islands.

Endangered Species Act of 1973 (ESA; 7 U.S.C. § 136, 16 

U.S.C. § 1531 et seq.) are applied in the freely associated 

states of the FSM, Palau, and the RMI as a legacy of these 

islands’ status until 1986 as Trust Territories administered 

by the United States.

Differing political status in relationship to the U.S. 

government amongst the island entities requires different 

bureaucratic arrangements and has different implications 

for the applicability of federal laws or eligibility for 

federal programs. Whereas Hawaii and the U.S. territories 

have consistently been eligible for all U.S. domestic 

forestry programs, this eligibility had to be clarified for 

the freely associated states in the 2008 Farm Bill. All the 

islands now avail themselves of a broad range of forest 

management programs offered by the Forest Service (see 

table C7-4). For the purposes of this report, the extension 
II–86 Assessing Forest Sustainability in the Tropical Forests of the United States

of Forest Service inventory activities through FIA to 

all the islands is of particular importance. One area 

where political status has resulted in definite distinctions 

between jurisdictions in federal treatment related to 

forestry is in the area of international aid, where, owing 

to their status as sovereign countries, the freely associated 

states are eligible for U.S. foreign assistance through the 

U.S. Agency for International Development and other 

channels.

In addition to providing assistance for public and private 

forest management on the islands, the Forest Service also 

directly manages forest lands that are part of the National 

Forest System. The El Yunque National Forest (NF) in 

Puerto Rico is the only national forest among the islands. 

It was designated in its entirety as the Luquillo Experimental Forest in 1956, as a UNESCO3

 Biosphere Reserve 

in 1976, and as a Long-Term Ecological Research (LTER) 

site in 1988. The El Yunque NF includes the federally designated El Toro Wilderness and three federally designated 

wild and scenic river segments. Estate Thomas Experimental Forest in the USVI was acquired in 1963 by the 

U.S. government to conduct tropical forest management 

research and currently is managed by the International 

Institute of Tropical Forestry for research and conservation education. The Hawaii Experimental Tropical Forest 

was established in 2007 as an experimental forest, but 

Table C7-4. Participation in U.S. Forest Service programs through 2010

Forest 

Stewardship 

Program

Cooperative 

Forestry 

Assistance

Urban and 

Community 

Forestry

Forest 

Health 

Protection

Forest 

Legacy

Fire and 

Aviation 

Management

Forest 

Inventory 

and Analysis

Research and 

Development

Caribbean:

 USVI Yes Yes Yes Partial Yes Yes Yes Yes

 Puerto Rico Yes Yes Yes Partial Yes Yes Yes Yes

Pacific:

 Hawaii Yes Yes Yes Yes Yes Yes 2010 Yes

 American

 Samoa

Yes Yes Yes Yes Partial Yes 2001 Yes

 RMI 2008

Partial

Yes Yes Yes No No 2008 No

 FSM 2008

Partial

Yes Yes Yes 2008+ 2008

Partial

2005 Yes

 CNMI Yes Yes Yes Yes No Yes 2004 No

 Guam Yes Yes Yes Yes Partial Yes 2002 Yes

 Palau 2008

Partial

Yes Yes Yes No 2008 2003 Yes

USVI = U.S. Virgin Islands; RMI = Republic of the Marshall Islands; FSM = Federated States of Micronesia; 

CNMI = Commonwealth of the Northern Mariana Islands.

underlying ownership and resource management responsibilities are held by the state of Hawaii. The National 

Park Service manages national parks with forest resources 

in the USVI, Hawaii, Guam, and AS (under a lease of 

communal lands), and the U.S. Department of Defense 

manages natural resources existing on military bases in 

Puerto Rico, Hawaii, Guam, and the CNMI. For each 

agency, management responsibilities include the need 

to gather information and solicit public comment in the 

formulation of management plans in compliance with the 

National Environmental Policy Act, Endangered Species 

Act, and other federal laws and regulations. 

Forest Inventory and Analysis is a Forest Service program 

administered by the agency’s Research and Development 

(R&D) division. The “Research” column in table C7-4 

indicates field activities undertaken by R&D scientists 

within each state/island during the 2003–2010 period. 

The other programs listed are implemented by state/island 

forestry agencies (see table C7-1) with grants from the 

Forest Service. “Yes” means the state/island has participated fully in the program since well before 2003. Dates 

indicate when the state/island first began participation 

during the 2003–2010 period (in most cases when the 

2008 Farm Bill made the freely associated states eligible). 

“Partial” means that the state/island had not yet engaged 

in full program implementation by 2010.

3 United Nations Educational, Scientific, and Cultural 

Organization.
Assessing Forest Sustainability in the Tropical Forests of the United States II–87

Regional Collaboration

Regional collaboration provides an opportunity for 

islands to pool their resources, learn from each other, and 

leverage outside resources from academia, the federal 

government or NGOs. A significant development in the 

Pacific has been the adoption and institutionalization of 

the “Micronesia Challenge.” In 2006, the heads of state 

of the RMI, FSM, CNMI, Guam, and Palau committed to 

“effectively conserve” at least 20 percent of the terrestrial 

resources (land acreage) in each jurisdiction by 2020. 

This effort provided the high-level political support that 

had been lacking for conservation in the region. The 

“Challenge” is institutionalized in the establishment 

of the regional Micronesian Conservation Trust, which 

is accumulating an endowment for conservation and 

implementing a variety of capacity-building programs; for 

the “Challenge” this includes a small staff and a steering 

committee representing regional and island government 

agencies and local NGOs. The “Challenge” necessarily 

requires the involvement and support of landowners, the 

general public, or both, depending upon the land tenure 

systems in place on each island or for each target ecosystem. Strategies and definitions have been developed; 

monitoring protocols for forested areas are being developed and will rely in part on FIA.

The islands host several research activities that represent the outermost geographic extent of broad-scale 

U.S. national research initiatives. Two such activities 

funded by the National Science Foundation (NSF) are 

the National Ecological Observatory Network (NEON) 

and the U.S. Critical Zone Observatory (CZO) program. 

NEON, with 60 sites ranging from Alaska and Hawaii 

across the United States to Puerto Rico, will be the first 

truly standardized continental network of research sites 

set up to discern ecological trends at such a large scale. 

The CZO program has six observatories across the United 

States, including one in Puerto Rico, to study the outer 

layer of the earth that sustains human life. It will provide 

data on interacting physical and biological systems that 

occur for watersheds with contrasting bedrock lithology 

but similar climatic and environmental histories. Another 

example is the Luquillo LTER site in Puerto Rico, which 

exists as part of a broader network of sites established by 

the NSF in North America, the Pacific, and Antarctica to 

conduct research on ecological issues over time. Puerto 

Rico also hosts the U.S. Department of Agriculture 

Caribbean Climate “Sub-Hub,” administered by the 

International Institute of Tropical Forestry. The site is part 

of a national network of climate hubs designed to share 

studies of climate change and adaptation strategies.

In 2009, the Secretary of the Interior, under Secretarial 

Order No. 3289, stipulated, and provided funding for the 

establishment 22 applied conservation science partnerships called Landscape Conservation Cooperatives. 

These relatively new efforts have the potential to affect 

sustainable forest management across all the islands. The 

Pacific Islands Climate Change Cooperative (http://piccc.

net) and the Caribbean Landscape Conservation Cooperative (http://caribbeanlcc.org) are part of this network. 

They consist of state and federal agencies, regional 

organizations, tribes, NGOs, universities, and other 

entities, and were founded with the intention of informing 

resource management decisions in an integrated fashion 

across landscapes—at a broader scale than any individual 

partner can encompass. 

References

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land-tenure customs by American law. Asian-Pacific 

Law and Policy Journal. 14(3): 167–240.

Maldonado, M.M.; Valdes-Pizzini, M.; Latoni, A.R.

1999. Owning and contesting El Yunque: forest 

resources, politics, and culture in Puerto Rico. 

Berkeley Journal of Sociology. 44(1999−2000): 

82−100.

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the conservation and sustainable management of 

temperate and boreal forests. 5th ed. 30 p. http://

www.montrealprocess.org/documents/publications/

techreports/MontrealProcessSeptember2015.pdf. 

(September 2016).

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encyclopedia of archaeology and traditional culture. 

Santa Barbara, CA: ABC-CLIO. 399 p.

U.S. Department of Agriculture Renewable Resources 

Extension Act Strategic Planning Team. [USDA

RREA] 2012. Sustaining the nation’s forest & 

rangeland resources for future generations. Athens, 

GA: Southern Regional Extension Forestry Strategic 

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[USDA FS]. 2011. National report on sustainable 

forests—2010. FS-979. Washington, DC: U.S. 

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