ATLAS

EL YUNQUE NATIONAL FOREST

Forest Service International Institute of Tropical Forestry General Technical Report IITF-GTR-47 JUNE 2018
In accordance with Federal civil rights law and U.S. Department of 

Agriculture (USDA) civil rights regulations and policies, the USDA, its 

agencies, offices, and employees, and institutions participating in or 

administering USDA programs are prohibited from discriminating based on 

race, color, national origin, religion, sex, gender identity (including gender 

expression), sexual orientation, disability, age, marital status, family/parental 

status, income derived from a public assistance program, political beliefs, 

or reprisal or retaliation for prior civil rights activity, in any program or 

activity conducted or funded by USDA (not all bases apply to all programs). 

Remedies and complaint filing deadlines vary by program or incident. 

Persons with disabilities who require alternative means of communication 

for program information (e.g., Braille, large print, audiotape, American Sign 

Language, etc.) should contact the responsible Agency or USDA’s TARGET 

Center at (202) 720-2600 (voice and TTY) or contact USDA through the 

Federal Relay Service at (800) 877-8339. 

To file a program discrimination complaint, complete the USDA Program 

Discrimination Complaint Form, AD-3027, found online at 

https://www.ascr.usda.gov/complaint_filing_cust.html and at any USDA 

office or write a letter addressed to USDA and provide in the letter all of the 

information requested in the form. To request a copy of the complaint form, 

call (866) 632-9992. Submit your completed form or letter to USDA by: 

(1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for 

Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250-9410; 

(2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov. 

USDA is an equal opportunity provider, employer, and lender.
El Yunque National Forest

and Luquillo Experimental Forest

Atlas

Maya Quiñones

Isabel K. Parés

William A. Gould

Grizelle González

Kathleen McGinley

Pedro Ríos

IITF-GTR-47

JUNE 2018
MAYA QUIÑONES is a geographer and cartographer, U.S. Department 

of Agriculture (USDA), Forest Service, International Institute of Tropical 

Forestry, Río Piedras, PR. Role: cartography, research, writing, analysis, 

graphic design, and translation. 

Email: mquinones@fs.fed.us

ISABEL K. PARÉS RAMOS is an environmental scientist, geographer, and 

urbanist for Urbánica, P.C., and is the Coordinator of the USDA Caribbean 

Climate Hub, Forest Service, International Institute of Tropical Forestry, Río 

Piedras, PR. Role: graphic design, research, cartography, analysis, writing, 

and translation. 

Email: iparesramos@fs.fed.us

WILLIAM A. GOULD is a research ecologist, USDA Forest Service, 

International Institute of Tropical Forestry, Río Piedras, PR, and is Director 

of the USDA Caribbean Climate Hub. Role: conception and writing. 

Email: wgould@fs.fed.us

GRIZELLE GONZÁLEZ is the project leader, Research and Development 

Unit, USDA Forest Service, International Institute of Tropical Forestry, 

Río Piedras, PR, and is an adjunct professor, Department of Biology and 

Department of Environmental Sciences, University of Puerto Rico. She 

is director of the Sabana Field Research Station in Luquillo, PR, and is 

principal investigator of the Luquillo Long Term Ecological Research 

Program and the Luquillo Critical Zone Observatory. Role: science 

research lead. Email: ggonzalez@fs.fed.us

KATHLEEN McGINLEY is a research social scientist, USDA Forest Service, 

International Institute of Tropical Forestry, and is an adjunct professor, 

Department of Forestry and Environmental Resources, North Carolina 

State University, Raleigh, NC. Role: social science research, analysis, and 

writing. Email: kmcginley@fs.fed.us

PEDRO RÍOS is a biological scientist and team leader of the Management 

and Ecosystems Plan for the El Yunque National Forest, USDA Forest 

Service, Río Grande, PR. Role: forest management lead. 

Email: prios@fs.fed.us

El Yunque National Forest Atlas 

U.S. Department of Agriculture, Forest Service

International Institute of Tropical Forestry

Jardín Botánico Sur

1201 Calle Ceiba, 

Río Piedras, Puerto Rico 00926-1119

T: (787) 766-5335 F: (787) 766-6302

Authors

@USFS_IITF

https://www.fs.usda.gov/iitf

General Technical Report IITF-GTR-47

April 2018
Contents

Acknowledgments 5

Preface 6

INTRODUCTION 8

Driving directions to the forest 10

Timeline 12

Forest facts 14

Ecosystem services 17

CHAPTER 1 — LAND 19

Topography 20

Landforms 21

Geology 22

Soils 24

Land Cover 26

CHAPTER 2 — WATER 27

Hydrography 28

Water resources 30

CHAPTER 3 — PLANTS AND ANIMALS 31

Vegetation 32

Vertebrate animals 36

Species of conservation concern 37

CHAPTER 4 — PEOPLE 39

Municipalities and other protected areas 40

Population 41

Socioeconomic statistics 43

CHAPTER 5 — RESEARCH

AND MANAGEMENT 45

Research 46

Designated areas 47

Infrastructure 48

CHAPTER 6 — RECREATION 51

Opening hours and contact information 52

Recreation areas 53

Recreation corridor along PR-191 54

Hiking Trails 55

References 57

Glossary 61

Abbreviations 63

3
4
The beautiful photographs found throughout this atlas were intrinsic to 

the design process and bringing El Yunque to life. Our thanks go out to 

the photographers who graciously shared their art with us. These include 

Gerald “Jerry” Bauer, Luis Andrei Muñoz, Gary Potts, Joel A. Mercado Díaz, 

the Baker Family, María M. Rivera, Carlos Estrada, Federico Moscoso 

Cintrón, and Omar Pérez-Reyes. 

We also thank José “Pepe” Ortega, Frank H. Wadsworth, and Luis A. Rivera 

for taking the time to meet with us and share their knowledge about the 

history, biology, and layout of the forest. Their input through interviews and 

personal communications was invaluable to the production of this atlas.

Our thanks go out to the authors of the quotes that begin each chapter; 

Marixa Maldonado for helping translate the text to Spanish; Sylvia Zavala 

Trías for her comments and suggestions on various draft versions and 

editing the Spanish translation; Enrique Martín Brea and Sandra Soto 

Bayó for their editorial comments on the Spanish version; Yaira Sofía 

Quiñones for helping with the front cover design; Ariel E. Lugo, Tamara 

Heartsill Scalley, Gary Potts, Alejandro Torres, Raymond Feliciano, Christian 

Torres Santana, Carlos Domínguez Cristóbal, and Peter L. Weaver for their 

insights and answering our questions; and Thomas J. Vázquez and Michael 

Hermann for their comments and suggestions on the cartographic design. 

We greatly appreciate all their support and enthusiasm. 

The Library at the International Institute of Tropical Forestry and its librarian, 

Gisel Reyes, were instrumental in providing us books and literature for 

our research and assisting us with the publication process, as were Frank 

Vanni, Keith D. Routman, and everyone in the Communications and 

Applications Program at the Pacific Northwest Research Station. 

Much of the research summarized here was performed under grants DEB0218039 and 1239764 from the National Science Foundation to the Institute 

of Tropical Ecosystem Studies, University of Puerto Rico, and the United 

States Department of Agriculture, Forest Service, International Institute of 

Tropical Forestry as part of the Long-Term Ecological Research Program in 

the Luquillo Experimental Forest. Support for the printing and development 

of this atlas was provided by USDA Forest Service Research and Development, USDA Caribbean Climate Hub, El Yunque National Forest, Caribbean Landscape Conservation Cooperative, State and Private Forestry, and 

Region 8 Biological and Physical Resources Program.

Thank you to the reviewers who offered their time to help improve this 

atlas. Finally, we thank all the scientists, technicians, administrators, and 

foresters who dedicate their lives to the study and management of El 

Yunque National Forest and the Luquillo Experimental Forest. They have 

helped broaden the science and management of tropical forests and have 

enlightened us about this very special place in the Puerto Rican culture. 

All research at the International Institute of Tropical Forestry is done in 

collaboration with the University of Puerto Rico.

Acknowledgments

5
El Yunque National Forest Atlas is a collaborative effort by the International 

Institute of Tropical Forestry and El Yunque National Forest to provide upto-date maps and analyses of spatial information of an important natural 

reserve in Puerto Rico and the only tropical forest in the National Forest 

System of the United States. 

El Yunque National Forest Atlas serves as a companion tool to the El Yunque 

National Forest 2014 Forest Plan Assessment Report, Phase One, under the 

U.S. Department of Agriculture (USDA), Forest Service 2012 Planning Rule. 

The assessment documents current ecological, socioeconomic, and cultural conditions of the forest and the surrounding landscape, as part of the 

El Yunque National Forest management plan revision process, which will 

establish requirements and constraints to make management decisions 

within the forest. The El Yunque National Forest 2014 Forest Plan Assessment 

Report is available at: https://go.usa.gov/cS5Tk.

This atlas visually summarizes information about El Yunque and the land 

where it rests, the water that flows from its peaks and the animals and 

plants that call it home; social and economic data from the municipalities that harbor it; management and research activities within the forest, 

and recreation and tourism activities available to visitors. The geographic 

information mapped in this atlas represents the latest available data as of 

March 2016. We used a numbered reference system, in which the information throughout the atlas has superscripted numbers that corresponds 

to the references listed in the references section, starting on page 57.

The information presented herein is based on the best available science 

as compiled by the authors and the El Yunque National Forest Management Plan Interdisciplinary Team, a group of professional scientists, foresters, and managers who were convened to work on the management 

plan revision process and the 2014 Forest Plan Assessment Report. Following, is a list of the contributors to the El Yunque National Forest 2014 Forest 

Plan Assessment Report.

Preface

6
• Alejandro Torres, cultural resources, Centro para la Conservación 

del Paisaje (CCP)

• Alexis Dragoni, hydrology, CCP

• Carmen Guerrero, planning, Iniciativa Para Un Desarrollo Sustentable (IDS)

• Carolyn Krupp, public affairs, USDA Forest Service

• Edgardo González, forest management, CCP

• Emrys Treasure, climate change, Template for Assessing Climate Change 

Impacts and Management Options

• Federico Moscoso Cintrón, public engagement, CCP

• Felipe Cano, wildlife biology, USDA Forest Service

• Grizelle González, research and science lead, USDA Forest Service

• José Ortega, recreation program, USDA Forest Service

• Kathleen McGinley, social science research, USDA Forest Service

• Lisa Jennings, natural resources, USDA Forest Service

• Luis A. Rivera, forestry, USDA Forest Service

• Luis Jorge Rivera Herrera, planning, IDS

• Nicole Hills, landscape architecture, USDA Forest Service

• Pedro Ríos, ecosystem management and planning team leader, USDA Forest 

Service

• Sharon Meléndez, archaeology, CCP

• Tinelle Bustam, recreation, USDA Forest Service

• William Jones, geographic information systems (GIS), USDA Forest Service

El Yunque National Forest 2014 Assessment Report Contributors

Name, role, and affiliation

• Delia Gómez, administrative support, USDA Forest Service

• Elba García, administrative support, USDA Forest Service

• Ivette Martínez, financial budget officer, USDA Forest Service

• Lucy Cruz, executive assistant to the Forest Supervisor, USDA Forest Service

• Maple Taylor, writer/editor, USDA Forest Service

• Marian Rodríguez, administrative support, contractor

• Michelle Ramos Morales, administrative support, contractor

• Rosa Ávila, budget officer, USDA Forest Service

• Yiraliz Rivera, administrative support, contractor

• Christian Torres Santana, forest health, USDA Forest Service

• Isabel Parés, cartographic support, Urbánica

• Maya Quiñones, GIS and cartographic support, USDA Forest Service

• William A. Gould, ecology research support, USDA Forest Service

Interdisciplinary Team

Administrative support

Scientific support

7
INTRODUCTION

8
EL YUNQUE National Forest, also designated as the 

Luquillo Experimental Forest, represents 

many things to many people. It is the easternmost, southernmost, wettest, most 

biologically diverse forest in the National Forest System of the United States. It has 

been recognized as a source of forest resources since the days of the Spanish Crown, 

and as a cultural resource since indigenous people inhabited Puerto Rico. In this atlas 

we present some of the most recently developed spatial information about El Yunque 

National Forest and surrounding lands.

The peaks of the Luquillo Mountains where the forest grows, reach heights of just 

over 1000 meters, and rising air masses release abundant rainfall from moisture-laden 

trade winds arriving from the east. In the short distance from the coast to the peaks, 

annual rainfall increases fourfold. Cloud forests rich in endemic species inhabit the 

peaks and streams flow down all sides of the mountains, bringing clean water to the 

people of Puerto Rico and connecting the land and sea environments. Fish and shrimp 

spawning in the sea live in the mountain streams. Birds, bats, coquís, and boas call 

the mountains home. Most of the oldest primary forest remnants of Puerto Rico are 

found in these mountains at higher elevations, with novel secondary forest stands in 

the lowlands. Together, they house more tree species than all the other national forests 

and grasslands combined. 

The forest is a source of recreation, research, and ecosystem services for the people 

of Puerto Rico, the Caribbean, and the world. This atlas maps the history, land and 

water resources, habitats and wildlife, and human uses of the forest so that managers, 

researchers, visitors, and neighbors have a shared vision of the value of El Yunque 

National Forest.

Photo by Jerry Bauer

9
!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!. !.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!. !.

!.

!.

!.

!.

!. !.

 ́

0 10 km

Ä!

PR-191

PR-3

PR-26

PR-66

San Juan

Isabel Segunda

Luquillo

Loíza

Carolina

Fajardo

Ceiba

Juncos

Las Piedras Humacao

Naguabo

Gurabo

Canóvanas Río Grande

San Lorenzo

Yabucoa

Maunabo

Patillas

Guayama

Arroyo

Cayey

Cidra

Aguas Buenas

Guaynabo

Bayamón

Caguas

Trujillo Alto

Cataño

National Forest

El Yunque

!.

Built-up areas

Protected areas

El Yunque National Forest

Main roads

Route

Urban centers

VIEQUES

Caribbean Sea

Toa Baja

Toa Alta

Dorado

Naranjito

Comerío

Aibonito

How to get to El Yunque from the Luis Muñoz Marín International Airport in San Juan, Puerto Rico

10
!.

Continue on PR-191 until you reach the forest. Near the entrance to the forest you will find the El Portal Visitor Center to your right.

Here, turn right and take your first left to PR-191— it’s a very short distance between turns.

Turn right into Triunfo street until it ends at Principal Street (PR-955).

Stay on PR-3 for approximately 6.3 km.

Continue on PR-66 until it ends on an intersecton with PR-3 Avenue. Turn right (east).

The highway will merge into highway PR-66 (toll road).

Exit main airport road (PR-17) and enter the Román Baldorioty de Castro highway (PR-26) toward the east.

!1

!1

!1

!1

!1

!1

!1

Enjoy the forest and all its wonders!

Driving directions:

Dewey

Atlantic Ocean

Caribbean Sea

Puerto Rico Cuba

Jamaica

The Bahamas

Venezuela

United States

of America

Lesser

Antilles

CULEBRA

GPS coordinates Forest Headquarters

El Portal Visitor Center

Palo Colorado Visitor Center

18° 20’ 18.7” N, 65° 45’ 39.9” W 

18° 20’ 22.2” N, 65° 45’ 43.2” W

18° 18’ 03.3” N, 65° 47’ 07.5” W

11
1903 1940–1943

1876 1905 1932 1934–1948

1931 1935

1953

Spanish

Crown

Lands

1949

Low 

demand

stops

timber 

extraction 

for 

charcoal 

production.

Gold 

mining 

on the 

Mameyes

River

inside the 

forest is 

abandoned.











Estimates show only 6% of Puerto Rico to be forested.

Major reforestation program begins.

1589 ha (3,926 acres) of land inside El Yunque are

reforested.

The Civilian Conservation Corps (CCC) constructs

105 km of roads, 80 km of trails, towers, picnic areas, 

cabins, a fish hatchery, swimming pools, and a 

restaurant in forests across the island.

60 million trees are given to island farmers.

First National Puerto Rico’s forests:

Forest Policy

Statement— 

acquisition of 

20 234 ha

(50,000 acres)

of forest across

the island. 

The USDA

publishes its 

first detailed 

report about 

the forest 

and its

resources. 

King of Spain

Alphonso XII

proclaims 

10 000 ha

(24,710 acres)

of forested land

in the Luquillo 

Mountains as a

forest reserve.

852 ha (2,105 

acres) of the 

Mameyes 

River valley 

is designated 

as the 

Baño de Oro

Research Area. 

The Forest Highway

(PR-191) and El Verde

Research Station are 

completed and long-term 

research plots begin.

Wartime needs boost El 

Yunque timber sales for 

charcoal production. 

Additional land 

surrounding El 

Yunque is 

purchased.

La Mina

Recreation 

Area opens. 

First

mahogany

plantations.

The Puerto 

Rican parrot 

population

is estimated 

at 2,000 birds. 

President Theodore

Roosevelt establishes

the Luquillo Forest

Reserve.

The Sabana River

valley was heavily

timbered. 

1946

IITF historical photo IITF historical photo IITF historical photo

1939

The USDA Forest 

Service Tropical 

Forest Experimental

Station (later known 

as the International 

Institute of Tropical 

Forestry) is 

established in 

Río Piedras.

El Yunque National Forest (1876 –2017)1

12
1961 1996–1997

1963 1976 2002 2005

1968 1971

2012

2009 2017

1956 1988

The forest is 

designated the 

Luquillo 

Experimental

Forest to 

recognize

the growing 

importance of 

research.

A revised forest

management

plan starts to 

be developed 

based on the 

best available

science and

input from the

public.

El Toro

Wilderness

Area is

established.

The Icacos, La

Mina, and

Mameyes Rivers

are designated

as “Wild and 

Scenic Rivers.” 

The Long Term

Ecological

Research (LTER)

program begins

in collaboration

with the 

University of

Puerto Rico. 

The forest is

designated 

as a

biosphere

reserve by

the United

Nations. 

Yokahú Observation Tower opens.

Juan A. Rivero discovers

Eleutherodactylus hedricki, a new

species of coquí tree frog.

The white-necked crow 

is last seen. 

New 

management

plan in final

revision

process.

The Luquillo 

Critical Zone 

Observatory

(LCZO) is 

established

within

El Yunque. 

El Portal Center exhibit

opens to promote

public education and

forest conservation.

The forest Land and

Resource Management 

Plan is approved.

The elfin woods

warbler (Dendroica

angelae), a bird 

endemic to 

Puerto Rico, is 

discovered at 

high elevations in 

the forest. 

The Puerto Rican 

parrot (Amazona 

vittata) is listed as an 

endangered species; 

an estimated 13 parrots 

remain in the wild. 

Formal research efforts 

to save the parrot begin. 

An

arboretum

of more

than 100

tropical

tree

species is

established.

Photo by Jerry Bauer

IITF historical photo

Photo by Jerry Bauer

Photo by Federico Moscoso Cintrón

13
El Yunque is the only tropical forest in the National Forest 

System of the United States.

It is the rainiest of all the U.S. national forests. 

It has high biodiversity, with 225 native tree species and

164 vertebrate species documented. 

It has the highest percentage of wilderness area (35%).

It is the only U.S. national forest located on an island.

It is the only U.S. national forest to be designated an 

experimental forest in its entirety.

El Yunque as a national forest in the 

National Forest System of the U.S.

 ́

69–78

78–82

82–86

86–87

87–91

57–62

62–64

64–66

66–69

69–73

(°F)

14–17

17–18

18–19

19–21

21–23

21–26

26–28

28–30

30–31

31–33

(°C)

Temperature

(annual average)

El Yunque 1500–2000 mm

118"–181" 3000–4598 mm

79"–118" 2000–3000 mm

59"–79"

39"–59"

28"–39"

1000–1500 mm

701–1000 mm

0 30 km

2

2

3, 4, 5

Climate Tropical maritime

Rainfall (annual) 3860 mm (152 inches) average for 

the whole forest; increases with elevation

Rainfall record 485 mm (19 inches) recorded on 

May 19, 1969, on Pico del Este

Temperature (average) 72 °F (22 °C) in the winter to 

86 °F (30 °C) in the summer

Temperature extremes Minimum = 52 °F (11 °C)

Maximum = 87 °F (32 °C)

Hurricanes 16 are documented to have 

(including hurricanes passed near or over the

Irma and María of 2017) mountains since 1738

Climate conditions in El Yunque National Forest 3

Maximum temperatures

Minimum temperatures

Annual precipitation (inches and mm)

Puerto Rico climate at a glance:

Photo by Gary Potts

14
0 20 km

 ́

Caribbean Sea

Atlantic Ocean

Culebra

Vieques

Isla de Mona

Desecheo

El Yunque Plains Hills Mountains Plateau

2007–present

1935–2007

1907–1935

1903–1907

1885–1898

<1500

El Yunque National Forest

Caribbean National Forest

Luquillo National Forest

Luquillo Forest Reserve

Sierra de Luquillo

Yukiyú by the Taíno Indians

OFFICIAL NAME YEAR

Area and other measurements:

 11 540 ha (28,516 acres)—total area

 122 km (76 miles)—perimeter

 53 km (33 miles)—roads

 30 km (19 miles)—recreational trails

 1.1 million visits per year

C e n t r a l M o u n t a i n s

Luquillo Mount ains

N o r t h e r n K a r s t B e l t

Cayey Mountains

Karst Conservation Zone

(private and public land)

Managed by

non-governmental organizations

Managed by

the government

Ten rivers and seven watersheds within the forest limits

636 native flora species

More than 1,000 different plant species

225 native tree species

164 animal species (24 endemic)

about 750,000 people

>30 meters

Cyrilla racemiflora and Magnolia splendens ≈1,000 years

Dacryodes excelsa and Manilkara bidentata

Five peaks have an elevation of more than 1000 meters

Uplifted Cretaceous marine volcaniclastic rocks and

Tertiary quartz diorite intrusive rocks

Elevations range from 120 to 1074 meters above sea level

11 migratory species of shrimp live in the forest streams

35 intakes on forest streams supply water for

60 are endemic to Puerto Rico

8 are endemic to the Luquillo Mountains

Birds = 107 species

Reptiles = 19 species

Mammals = 16 species

Amphibians = 15 species

Fish = 7 species

Geology

Topography

Hydrology

Tallest trees

Oldest trees

Flora

(vegetation)

Fauna

(vertebrates)

Physiography of Puerto Rico

Protected Areas of Puerto Rico

10

6

3, 8, 9

7

3

3

3

3

3

3

3

El Yunque National Forest quick facts 15
16
Ecosystem Services are commonly defined as benefits humans obtain from nature. The Millennium 

Ecosystem Assessment, a 4-year United Nations assessment of the condition and trends of the 

world’s ecosystems, categorizes ecosystem services as:

11

El Yunque National Forest provides a variety of ecosystem services—including clean air, fresh water, 

and recreation—that are essential to the well-being of people in communities surrounding the forest 

and beyond. Many of these goods and services are traditionally viewed as free benefits to society, 

or “public goods”—wildlife habitat and diversity, watershed services, carbon storage, and scenic 

landscapes, for example. Lacking a formal market, these natural assets are traditionally absent from 

society’s balance sheet; their critical contributions are often overlooked in public, corporate, and 

individual decisionmaking. When our forests are undervalued, they are increasingly susceptible to

development pressures and conversion. Recognizing forest ecosystems as natural assets with 

economic and social value can help promote conservation and more effective decisionmaking. 

12

Cultural services

Supporting services

Regulating services

Provisioning services

Processes that help regulate the climate, air quality, water amount and

quality, disease and plant production through pollination, among others.

Processes that support the ecosystems and habitats that provide us with

these services such as soil formation, nutrient cycling, and genetic diversity.

Nonphysical benefits to humans such as science and education, 

aesthetic, recreation, spiritual and historical values.

Provide food, fresh water, fuel, fiber, and other goods.

El Yunque National Forest Ecosystem Services

Photo by Luis Andrei Muñoz

17
18
CHAPTER 1—LAND

“The Luquillo Mountains rise abruptly from the sea to an elevation of 1000 

meters, creating a steep topography that stands out in the northeast of 

Puerto Rico. No other formation obstructs the view toward or from the 

magnificent mountains in a 30-kilometer radius. Cloud systems originating 

in the north Atlantic, Africa, and the northeast of the United States cover the 

Luquillo Mountains at 600 meters.”

—Ariel E. Lugo,

director of the International Institute of Tropical Forestry Photo by Gary Potts

19
 ́

0 10 km

0–120

120–400

400–600

600–900

900–1338

Moist air from the trade winds arriving from the 

Atlantic Ocean cools and condenses as it rises 

up the steep mountain slopes, resulting in the 

mountain peaks being cloaked in cloud cover most 

of the time. February and March are the months 

when the peaks are most likely to be free of clouds. 

The continuous rainfall at the peaks transforms 

into the headwaters for six major rivers: Río 

Espíritu Santo, Río Grande de Loíza, Río Blanco, 

Río Mameyes, Río Fajardo, and Río Sabana.

El Yunque National Forest is situated in the 

Luquillo Mountains, which rise from the coast 

to over 1000 m above sea level. El Toro Peak 

(1074 m) is the highest point within the forest. 

Many environmental gradients reach their 

extreme values at the mountain summits, 

such as the highest wind speeds, lowest air 

temperatures, lowest incoming sunlight, highest 

rainfall, and lowest oxygen concentrations in 

the soil.

Climate at the peaks

3, 7, 13

3

3

Most of El Yunque National Forest lies 

between 400 and 900 m in elevation; only 

5 percent lies above 900 m. Five peaks in 

the forest exceed 1000 m in elevation: El 

Toro, El Yunque, Pico del Este, Pico del 

Oeste, and El Cacique. The lowest point 

is along the northeastern boundary near 

the town of Sabana.

FOREST PEAKS

Hydrologic units

El Yunque National Forest

Elevation (m)

750

931

941

968

1020

1025

1051

1065

1074

1.

2.

3.

4.

5.

6.

7.

8.

9.

El Negro

La Mina

Mount Britton

Los Picachos

Cacique

Pico del Oeste

Pico del Este

El Yunque

El Toro

Name Elevation (m)

Elevation and peaks of El Yunque

TOPOGRAPHY

Photo by Jerry Bauer

2010 digitital aerial photos 14

1

2

3

4

5

6

7

8

9

20
 ́

0 3 km

7%

6%

8%

29%

32%

15%

1%

1% 1%

<1%

Flat summit

Slope bottom

Cliff

Slope crest

Upper slope

Steep slope

Moderately steep slope

Side slope

Low slope

Plain

Landforms diagram: location across the landscape

Landforms distribution

within El Yunque

More than half of the landslides in Puerto 

Rico are caused by intense rains and winds 

associated with disturbances such as 

hurricanes, tropical storms, and tropical 

depressions. In El Yunque National Forest, 

the greatest number of landslides occur 

between 600 and 800 m in elevation. Most 

of these occur during the hurricane season 

from June through October.

LANDSLIDES

 Human settlement, including 

past agriculture and tree planting 

at lower elevations, has imposed 

changes on the El Yunque 

landscape since the early 1800s. 

However, most of the terrain 

above 600 m in elevation 

escaped human intervention 

because of inaccessible steep 

slopes and heavy rainfall levels. 

Landforms characterize the topography of the Earth's 

surface. Twelve landforms have been mapped for 

Puerto Rico, ten of which are found within El Yunque

National Forest. The rugged terrain of the Luquillo 

Mountains, where the forest is located, is mainly 

formed by slopes that range from low to steep angles. 

Flat terrain is rare in the forest, and comes in the form 

of plains, slope bottoms, and flat summits.

16

3

15

e shape of the forest

LANDFORMS

3

15

Photo by Jerry Bauer

21
 ́

0 8 km

Geologic terranes of El Yunque and surrounding lands

GEOLOGY

tectonic fault lines found across the island today. Large deposits 

of marine sediments and alluvium are found along the north, 

coastal regions, and valleys of Puerto Rico; the product of 

weathering and erosion processes and tectonic history.

Most of El Yunque lies over marine volcaniclastic and intrusive 

igneous rocks from the Cretaceous and Tertiary periods.

Puerto Rico is a volcanic island. The oldest geologic formations, 

found in the southwestern side of the island, date back to the late 

Jurassic period 150 million years ago. Over half of Puerto Rico is 

formed by igneous and metamorphic rocks from volcanic activity 

that lasted from the late Jurassic period to the Eocene epoch. 

Tectonic movement rotated, arched, sank, and uplifted the land 

masses, further defining the complex terranes and creating the 

17

17

El Yunque National Forest

Tectonic fault lines

Volcaniclastic

Submarine basalt and chert

Intrusive

Nonvolcaniclastic

Alteration

Geology of Puerto Rico

Geologic terranes

Areas of rock formed from magma 

erupted from a volcano. In Puerto Rico, 

most of the volcaniclastic terrane 

originates from the eruption of 

underwater volcanoes during the 

Cretaceous period. Small deposits of 

volcaniclastic rocks formed above 

water are also present in the island.

Areas of basalt rock that formed from 

rapid cooling lava under the ocean and 

chert sedimentary rocks. In Puerto Rico, 

chert is found in association with basalt.

Areas made of intrusive rocks. Intrusive 

rocks are igneous rocks made of 

hardened magma that form below the 

surface. In Puerto Rico, copper, gold and 

other economically valuable metals and 

minerals are found in intrusive terranes.

Areas made of metamorphic rocks of 

volcanic origin or hydrothermally altered 

rocks of unknown origin. Hydrothermal 

alteration occurs when hot water 

changes the chemical composition of a 

rock. In Puerto Rico, altered rocks are 

widespread and represent many 

different levels of alteration intensity.

Rock deposits of biogenic material and 

other rocks without volcanic material. 

In Puerto Rico, this terrane consists of 

superficial deposits of alluvium, beach 

and swamp deposits, landslide areas, 

artificial fill, and fault breccia—rocks 

formed by tectonic forces from broken 

fragments of minerals and other rocks.

22
0 3 km

 ́

Kh

TKh

Kfa Kta

Klo

Qa

Kf

TKap

Kd

Klo

Klo

Klo

Klo TKh

TKh

Kfa

Kfa

Kfa

Kf

Qa

Qa

Qa

Qa

Kh

Kh

Kta

TKap

Qa

TKh

TKap

Klo

Kh

Kta

Kfa

Kf

Kd

Unconsolidated

sand and gravel.

Igneous plutonic rocks that formed beneath

the earth’s surface. It also contains minerals

such as quartz, plagioclase, and biotite.

Volcanic rocks, igneous rocks with

large-grained crystals, and the minerals

augite and plagioclase.

Volcanic rocks, submarine volcanic

rocks and glass, and volcanic

sandstone and mudstone.

Sedimentary rocks, like sandstone

and mudstone, made up of volcanic

rock pieces and minerals.

Fine to coarse grained calcareous—

containing calcium carbonate—

volcanic sandstone and mudstone

with minor volcanic rock pieces.

Sedimentary rocks made of

consolidated ash, with larger pieces

of volcanic rock interbedded with

sandstone and cherty siltstone.

Volcanic rocks interlayered with other

volcanic rocks, submarine volcanic

rocks, sandstone, and siltstone.

Interbedded volcanic rocks,

sandstone and crystal formations

from consolidated volcanic ash.

Alluvium

Hornblende quartz-diorite

Augite andesite porphyry

Lomas Formation

Hato Puerco Formation

Tabonuco Formation

Fajardo Formation

Figuera Lava

Daguao Formation

Early Cretaceous Late Cretaceous Quaternary

El Yunque National Forest geologic formations

GEOLOGY

17

23
 ́

0 2 km

Ultisols Inceptisols Oxisols

These highly weathered soils cover 8% of 

the world’s ice-free land surface and 

develop in humid climates, characteristically 

in tropical and subtropical regions. Most 

oxisols are low in fertility and tend to have 

high permeability and resistance to 

compaction. In El Yunque, oxisols are found 

on geomorphologically stable surfaces.

These are the most common soils in the 

world, covering 17% of the world’s ice-free 

land surface. They develop in a wide 

range of climates and exhibit a wide range 

of characteristics. In El Yunque, inceptisols 

are weakly developed and are mostly 

found on unconsolidated sediment 

deposits shallow to bedrock.

These soils cover 8% of the world’s ice-free 

land surface. They develop in humid climates 

from intense weathering and leaching 

processes. In El Yunque, ultisols form on 

weathered porous rocks and unconsolidated 

sediment deposits and generally have a low 

nutrient content with organic matter limited 

to the upper portion of the soils.

Other factors that influence soil 

properties in El Yunque include 

landslides, hurricanes, global wind 

patterns, Saharan dust, proximity to 

the coast, and the vegetation 

communities that grow in the forest. 

Land use history also affects the 

soils of El Yunque, especially in the 

lower slopes, where past agriculture 

and grazing activities have caused 

soil erosion and degradation.

Soils form as a result of the effects 

of climate, living organisms, 

topographic relief, and time on the 

rocks and parent material of an area. 

The dominant parent materials found 

in El Yunque are igneous and volcanic 

rocks, which are strongly influenced 

by the climate, especially rainfall, and 

the steep topography of the area.

In El Yunque National Forest, scientists 

have described 23 soil types and 

complexes—soils made from a 

combination of two or more soil 

types.

58%

35%

7%

Soil order

distribution in 

El Yunque

The soils of El Yunque National Forest are classified into three soil 

orders. Soil orders are the top rank within the U.S. Department of 

Agriculture (USDA) Soil Taxonomy classification system developed 

by the USDA and the National Cooperative Soil Survey. Twelve soil 

orders are described globally, of which ten occur in Puerto Rico.

Soil orders classify global soils according to their horizons 

and soil-forming processes. Soil horizons are horizontal 

layers found within the soil, the product of these soil-forming 

processes, and hence reveal information about the history 

and characteristics of the soil.

3

21

21

20

3, 21, 22

20, 21

20

19

18

Soils in El Yunque

Soil orders

Soil orders

SOILS

Soil profile from

research

conducted

at El Yunque

National Forest 21

24
 ́

0 2 km

The strongly weathered soils of El Yunque lose plantessential nutrients, such as calcium and phosphorus, 

through the intense leaching caused by the heavy 

regular rainfall on the steep topography. However, 

after decades of research at El Yunque National 

Forest, it was found that the clouds that arrive to the 

Luquillo Mountains are laden with marine aerosols, 

dust, ash, and pollution, which influence and supplement the nutrients and chemicals in the soil. 

The African Saharan dust in particular provides vital 

geochemical constituents to the soils of the Luquillo 

Mountains and contributes to the fertility of the El 

Yunque ecosystems. Dust from the SaharaSahel region in Africa is transported to the American 

tropics by the trade winds; in Puerto Rico, seasonal 

peaks occur in June and July. In some areas of 

El Yunque National Forest, Saharan dust is mixed 

into the soil profile to over one meter deep.

Saharan dust

Dominantly hydric

soils

Partially hydric soils

Nonhydric soils

600 m elevation contour

Hydric soils form in water-saturated or flooded areas, 

in which anaerobic conditions develop within the soil. 

These conditions alter the biological and chemical 

reactions in the soil, creating unique properties where 

only specialized plants and microorganisms can survive. 

Hydric soils, hydrophytic vegetation, and wetland hydrology are the three essential characteristics of wetlands. 

Half of El Yunque’s surface is covered by dominantly

or partially hydric soils. Partially hydric soils have 

hydric non-dominant components. Most of the hydric 

soils are found near the peaks at over 600 m in 

elevation. This is the approximate elevation 

where clouds form in El Yunque.

21

23, 24

23, 24

21, 23, 24

21

3, 7

22

22

Hydric soils

SOILS

Photo by Jerry Bauer

25
Naguabo

Ceiba

Las Piedras

Juncos

Canóvanas

Río Grande

Luquillo

Fajardo

Naguabo

Ceiba

Las Piedras

Juncos

Canóvanas

Río Grande

Luquillo

Fajardo

Naguabo Ceiba Las

Piedras Juncos

Luquillo Fajardo Río

Grande Canóvanas

0 5 km

 ́

2010 land cover distribution at the municipal level

6027

1817

309

208

14,892

4,490

763

514

72

22

4

2

Forest

Pasture

Shrub

Urban

Land cover Hectares Acres Percentage

El Yunque immediate surroundings 

(1 km from the forest boundary)

43

36

10

6

3

32 638

27 017

7745

4227

2423

80,649

66,760

19,138

10,444

5,987

Forest

Pasture

Urban

Shrub

Wetland

Land cover Hectares Acres Percentage

Municipalities of El Yunque

Wetland

Forest

Shrub

Water

Pasture

Urban

Bare ground

Municipal boundaries

Forest boundary

1 km from the forest boundary

Land cover maps display vegetation, bare ground, 

built-up areas, and other physical cover on the 

earth’s surface, facilitating the description, analysis, 

and research of the world around us. Scientists and 

technicians often use aerial photos or satellite 

images to create these maps. The land cover of El 

Yunque region shown here was created by Tania 

López-Marrero and Annie Hermansen-Báez using 

aerial photographs taken in 2010.

Land cover maps

El Yunque National Forest provides a variety of 

ecosystem goods and services, such as clean air, 

water, biodiversity, and recreation. The availability of 

these ecosystem services is influenced not just by the 

conservation of trees and other natural habitats inside 

the forest, but by how the land surrounding the forest 

is used. For example, surrounding forests help protect 

watersheds from soil erosion, serve as filters to 

produce clean water, and provide habitat and food 

for El Yunque’s fauna. The conservation of these 

areas is especially important for animals that move 

from the coast to the mountains and back 

throughout their life cycles, such as the freshwater 

shrimps that live in the waters of El Yunque.

26

26

12

El Yunque surroundings in 2010

LAND COVER

Landsat 8 satellite image25

26
CHAPTER 2—WATER

“El Yunque is a story that never ends! The experience of 

documenting how moisture carried by the wind creates 

mist-covered scenes at the top of the mountain to 

produce the freshwater we drink was the first of many 

fascinating stories I produced. Through the years, I have 

shared with the researchers and interpreters of El 

Yunque tales starring the magnitude of the flora that 

adapts to extreme conditions to survive, or how our 

Taíno natives revered these White Lands. To 

communicate stories such as the survival of our 

charismatic parrot or the important role of a simple 

earthworm is to fulfill my social responsibility in an 

attempt for more Puerto Ricans to understand how our 

forest works so they can protect it.”

—María Falcón, communicator and educator

Photo by Maya Quiñones

27
<120

120–400

400–600600–900

900–1073

 ́

0 5 km

Río Gurabo

Río G r a nde de Loíza

Rí o

Espíritu

Santo

Rí o

M ameyes

Río

Sabana

Río Fa jardo

Río Santia g o

Rí o Blanco

Rí o

Grande

El Yunque 

National Forest

Hydrologic units

Streams

Main rivers Elevation (m)

Ten rivers originate within El Yunque National Forest. 

Four of these drain nearly 80 percent of the water of 

the forest—Río Blanco, Río Espíritu Santo, Río 

Grande de Loíza, and Río Mameyes. El Yunque is 

part of three hydrologic units mapped at a scale of 

40,000 to 250,000 acres (16 000 to 100 000 ha) by 

the U.S. Geological Survey in cooperation with the 

U.S. Department of Agriculture, Natural Resources 

Conservation Service. Hydrologic units represent 

drainage areas upstream from a specific point on 

a river, or similar surface waters. 27

3

Rivers and hydrologic units

HYDROGRAPHY

Río

Canovanillas

Río Ca

nóva

n

as

Río Mameyes

Río Pit a h ay a

28
 ́

0 5 km

Río

Espíritu Santo

Río

Grande

Quebrada Grande

Quebrada Sonadora

Quebrada

Jim énez

Quebra

d a

Ta

bonuco

Río Mameyes

Quebr ada Juan Diego

Río

de la M i na

Rí o Saba na

(Luquillo)

Río del Crist al

Río C amándulas

Río Pitah a y a

Río Fajardo

Quebrada

Gra nde (Naguabo)

Quebra

da Mai zales

Río Prieto

Río Icaco

Rí

s

o Saban a (Naguabo)

Río Gurabo

Rí o

Cub uy (Naguabo)

Río

Blanc o

Río Cubuy ( Canóvana s)

Río

Ca n ó v a n a s

Río Canovanillas

Río Herrera

Quebra

da

Grande

Río Santi a go

Subwatersheds

Streams

Main rivers

El Yunque

Average annual rainfall in El Yunque is 3860 mm (152 inches), equivalent to over 100 billion gallons of water per year. Some areas in 

the uppermost cloud forest receive more than 5000 mm (200 inches) 

annually. It usually rains the most during spring and autumn. On 

average, 60–65% of the rainfall in the forest turns into stream runoff, 

while 35–40% is lost through evapotranspiration.

Rainfall in El Yunque

The rivers in El Yunque National Forest 

are characterized by deep and narrow 

banks with clear crystalline water and an 

accumulation of large boulders. The 

streams flow through long profiles of 

steep elevational gradients, over waterfalls and rapids of exposed bedrock and 

boulders, moving downstream to wider 

valleys, where boulders become smaller 

and more scattered. Typical of mountainous regions across the Caribbean 

Greater Antilles, the steep hillsides, high 

annual rainfall, periodic short-duration 

high-magnitude rainfall events caused 

by storms and hurricanes, and volcanic 

bedrock are the prime factors that 

influence the shape and behavior of the 

rivers in the Luquillo Mountains where 

the forest grows.

 The high rainfall and steep topography 

also create dangerous river flash floods, 

in which large volumes of floodwater are 

carried downhill at high velocity within 

minutes to hours after rainstorms. 

Rainfall events at the top of the mountains can cause flash floods in the lower 

slopes without warning. 

3, 4

3, 7

4

3, 28

28

28

e shape of the rivers inside El Yunque

RIVER MORPHOLOGY

Quebrada Sonadora, 

Photo by Gary Potts

29
op

op

op

op

op

op

op

op

op

op

op

op op op

op

op op

op

op

op

op

op

op

op

op

opop op

op op

op

op

op

opop

op

op

op

op op

op

op

op op op

op

op

op

op op

op op op op

op

op

op

op

op

opop

op

op

op

op

op

op

op

op

op

op

op

op op op op

op

op

p op

p

p

p op

op

op

op

op

op op

op

Fajardo

Ceiba

Naguabo

Las 

Piedras

Juncos

Canóvanas

Río Grande

Luquillo

Fajardo

Ceiba

Naguabo

Las 

Piedras

Juncos

Canóvanas

Río Grande

Luquillo

11–19 Mgal/day

4–10 Mgal/day

<3 Mgal/day

No data

71–99 g/p/d 36–50 g/p/d

51–70 g/p/d <35 g/p/d

Water-use data for 2010 from 

the National Water Information System from the USGS 

reports that water withdrawals 

in Puerto Rico totaled 

677 million gallons per day 

(Mgal/day), of which 230 

Mgal/day were for domestic 

use. In the municipalities that 

encompass El Yunque, withdrawals totaled 58 Mgal/day, 

while domestic use totaled 

15 Mgal/day; domestic use 

ranged from 26–99 gallons 

per person per day (g/p/d).

Water withdrawals in 2010 Water for domestic use in 2010

Shrimp account for 95% of the biomass living in 

the rivers and streams of El Yunque. These tiny 

crustaceans are important decomposers, breaking 

down leaves and algae and contributing to the 

health of aquatic ecosystems. Shrimp migrate 

upstream to the Luquillo Mountains from coastal 

waters where they hatch. Dams and water intakes 

break stream connectivity, affecting shrimp 

migration. However, intakes like the one installed in 

Río Mameyes are especially designed to alter the 

river channel less than low-head dams and have 

minimal effect on migratory aquatic species.

Freshwater Shrimp

op Water intake

In 2004, there were 34 intakes withdrawing over 66 million gallons of 

water per day from the forest, compared to 51 million gallons in 1994.

Water intakes

U.S. Geological Survey (USGS)

Puerto Rico Department of Natural

and Environmental Resources

U.S. Environmental Protection Agency

Puerto Rico Environmental Quality Board

Extraction (regulation)

Water quality

Extraction (monitoring)

Regulatory agencies

On a typical day, over half of all 

water flowing from the forest is 

extracted for municipal use and 

human consumption. Based on 

the cost paid by consumers, the 

water extracted from the streams 

that flow from the Luquillo 

Mountains is worth about $25 

million per year.

DID YOU KNOW?

Water for public consumption is an 

important service provided by El 

Yunque National Forest. Forest cover 

is associated with suitable water 

conditions for ecosystem processes 

and consumption, while bare ground 

and built-up areas increase 

sedimentation and flash floods, and 

contribute to lower water quality.

The water that runs through El 

Yunque’s rivers is documented as 

the cleanest on the island with highquality conditions. In 2014, Puerto 

Rico had 3.5 million inhabitants, of 

which about 20% depend on the 

water El Yunque National Forest 

supplies. 

3

3, 32

32

31

31

31 31

30

7

7

3

7, 29

7, 29

29

Water extraction and use

WATER RESOURCES

Freshwater shrimp, Atya innocuous

Photo by Omar Pérez-Reyes

30
CHAPTER 3—PLANTS AND ANIMALS

“El Yunque is tropical forest beauty. To me it is also 

tropical forestry. To protect its soil and water quality, it 

resisted surrounding deforestation. More than half is left 

natural. Its watershed area was doubled and successfully 

reforested, testing diverse tropical trees. Terrestrial and 

aquatic fauna have been retained. It trained more than 

200 forestry students from other tropical countries. Longtime tree measurements exposed growth rates and wood 

volume per tree. Then, the trees showed me the capability 

of maturing timber (or restoring forests) in half the time of 

unmanaged forests.”

—Frank H. Wadsworth, 

forester and conservationist, 

former director of the Institute of Tropical Forestry

Photo by Gary Potts

31
 ́

0 4 km

Nonforest (grasslands, shrubland, and natural barrens)

Developed land

Mature Tabebuia/Eugenia forest

Mature sierra palm forest

Mature palo colorado forest

Mature tabonuco forest

Secondary forest

Riparian forest

The effects of climate change on a tropical forest ecosystem such as El Yunque 

are complex and are still being studied. Records show decreasing rainfall totals 

and increasing temperatures over the last century in the Luquillo Mountains. 

Furthermore, statistical models of future climate for Puerto Rico predict an increase 

in temperatures of 4° to 9° Celsius, declines in rainfall, and an increase in drought 

intensity and extremes by the end of this century. In general, climate change has 

the potential to transform El Yunque’s forest structure and function, altering its 

species composition and distribution along the elevational gradient. 

The vegetation in the Luquillo Mountains is influenced by evolution, 

climate, natural disturbances, land use history, and the steep 

elevational gradient, which rises abruptly to over 1000 m in elevation 

in a short distance of 8 km (5 miles) from the coast. Forest types 

in El Yunque are not homogenous or static, and boundaries are not 

always clear between vegetation associations. Recurrent natural 

events such as hurricanes and landslides also affect forest structure 

and species composition, keeping the forest in flux. However, 

spatial patterns formed by the tree canopy of vegetation 

communities in El Yunque are observed in air photos 

and satellite images, which facilitate the mapping of 

forest types. The map shown here 

simplifies the vegetation associations 

found in El Yunque and serves as an 

important tool for describing and 

managing the forest. Forest types are 

identified by cloud cover and life zone 

with a brief description in 

the following pages.

34

35

34

7, 34

7

7, 33

33

32

7, 32, 33

CLIMATE CHANGE AND THE FOREST

Forest types

Forest classication

VEGETATION

Photo by Jerry Bauer

32
< 100 

100–300 

300–600 

600–800 

800–1000 

> 1000 

 ́ 0 4 km

Secondary montane wet cloud forest

Secondary montane wet forest

Secondary submontane moist forest

Riparian montane rain and wet cloud forest

Riparian montane rain and wet forest

Riparian submontane moist forest

Elevation (meters)

e forest types—

altitude, moisture 

and the clouds

The ecological life zones 

describe broad bioclimatic 

units that bear a close 

relationship to natural and 

biologically meaningful 

landscapes. These were 

developed using the 

Holdridge model, in which 

precipitation and biotemperature data are used to 

delineate the zones, which 

are then classified based on 

latitudinal region, altitudinal 

belt, and humidity province. 

The ecological life zones of 

El Yunque help subdivide the 

forest types into moist, wet, 

or rain, and montane or 

submontane.

Secondary forests are the result of forest regeneration 

following human disturbance and deforestation of forest 

ecosystems. These new forests have a different species 

composition than the original forest cover, often including 

a combination of introduced and native species forming 

novel communities that are adapted to anthropogenic 

environmental conditions. The secondary forest found in 

El Yunque National Forest is the result of reforestation of 

agricultural land and the planting of commercial timber 

tree species, mainly mahogany, during the 1930s and 1960s.

The riparian zone is located at the interface between the 

land and river or stream. The vegetation in these areas 

is similar to surrounding slopes. For management 

purposes, the riparian forests within El Yunque National 

Forest are defined at 100 feet (30.48 m) from each river 

or stream bank.

Frequent cloud cover over 

the vegetation in the 

mountains affects the 

structure of the forest stands. 

In El Yunque, clouds form at 

approximately 600 m in 

elevation, hence forest types 

above this elevation are 

classified as cloud forest.

The main forest types found 

in El Yunque are further 

defined by their location 

within the forest.

37

36

7

7

7

7

Secondary forest

Riparian forest

Photo by Jerry Bauer

Photo by Jerry Bauer

33
 ́ 0 4 km

The palo colorado forest has tree canopies that reach about 15 m (50 

feet) in height. Sixty-five tree species have been recorded in this forest 

type, with 10 species accounting for over 70% of the total count. Tree 

species distribution varies according to topography and aspect, with 

different species dominating the ravines, ridges, and slopes. On the 

forest floor, bromeliads, root mats, and exposed soil are common.

The tabonuco forest is dominated by tall trees with canopies that reach 

heights of about 30 m (98 feet), and woody vines. This forest type holds 

more than 80 tree species. The tabonuco rain forest within the 

subtropical rain forest life zone is characterized by an abundance of 

rainfall with an estimated annual runoff of 3400 mm (130 inches), more 

than twice the annual rainfall received by most areas in the world.

Mature palo colorado montane rain cloud forest

Mature palo colorado montane wet cloud forest

Mature tabonuco montane rain forest

Mature tabonuco montane wet forest

6. TABEBUIA/EUGENIA

WOODLAND: occurs on the 

highest mountain peaks above 

900 m. Derives its name from 

two of its most abundant tree 

species: Tabebuia rigida and 

Eugenia borinquensis. Shrubs, 

mosses, epiphytes, and sierra 

palm are also common within 

this forest type.

5. SIERRA PALM FOREST: 

composed mainly of sierra 

palm, Prestoea montana. This 

forest type can be found above 

elevations of 450 m, mostly on 

steep slopes and saturated 

soils. 

4. PALO COLORADO FOREST: 

named after the palo colorado 

tree, Cyrilla racemiflora, it is 

located between 600 m and 

1000 m, mostly on saturated 

soils. 

3. TABONUCO FOREST: lies 

between 150 m and 700 m in 

elevation. Dominant tree species

are Dacryodes excelsa, tabonuco,

and Sloanea berteriana, motillo. 

2. SECONDARY FOREST: 

Historical records report timber 

plantation plots located at 180 m 

to 600 m; however, planted areas 

from historical maps range in 

elevation from 50 m to 800 m.

1. RIPARIAN FOREST: Seen 

across all elevations, this forest 

type is found along rivers and 

streams.

Palo colorado forest

Tabonuco forest

Distribution of forest

types by elevation

3

7

32, 33

32

33

3

3

Photo by Jerry Bauer

Photo by Jerry Bauer

34
< 100

100–300

300–600

600–800

800–1000

> 1000

The Tabebuia/Eugenia elfin woodland, also known as dwarf 

forest, occupies the mountain peaks of El Yunque where the 

combination of low temperatures, high humidity and rainfall, 

high winds, and almost constant cloud cover create habitat 

conditions that slow and stunt tree growth. Fewer species 

have adapted to survive on the exposed summits, with only 

four accounting for 70% of this forest type: Tabebuia rigida, 

Eugenia borinquensis, Ocotea spathulata, and Cyathea bryophila. 

The tree canopies typically range from 1 to 6 m in height. This 

forest type shelters 20 endemic tree species and protects the 

highest slopes and summits from erosion. Tree trunks here 

are seldom straight. 

The sierra palm forest, also known as palm brakes, is dominated by sierra palm, 

Prestoea montana, which typically accounts for over half of its total tree count. 

The palm canopies can reach 15 m (50 feet) in height and tend to survive 

hurricanes very well. Tree species from surrounding forest types can be 

found among the predominant palms; and sparse grasses or rocks cover the 

ground. Palm fruits are part of the basic diet of the Puerto Rican parrot.

Puerto Rico’s forests, abundant 

across the entire island on the 

arrival of the Europeans in the 

16th century, were converted 

to pastures and cropland, and 

its trees were used for timber 

and charcoal. By the late 1940s, 

only about 6% of Puerto Rico’s 

land area had any forest left, 

making it “one of the most 

severely deforested and 

eroded regions in the world.”

A combination of socioeconomic changes, the abandonment of agriculture, migration 

from the countryside to the 

cities and to the United States, 

reforestation and silvicultural 

campaigns by the government, 

natural forest regeneration, 

and the establishment of a 

tropical forestry research 

station allowed and encouraged forest regeneration 

across the country. As of 

2009, Puerto Rico’s forests 

covered 55% of its territory.

El Yunque National Forest, 

unique among Puerto Rico's 

forests, holds some of the few 

remnants of primary or ‘virgin’ 

forest in the island—forest that 

has not been greatly disturbed 

and therefore has kept its 

original structure and species 

composition.

Mature Tabebuia/Eugenia elfin woodland montane rain cloud forest

Mature Tabebuia/Eugenia elfin woodland montane wet cloud forest

Mature sierra palm montane rain cloud forest

Mature sierra palm montane wet cloud forest

Mature sierra palm montane wet forest

Elevation (meters)

Tabebuia/Eugenia

elfin woodland

Sierra palm forest

Puerto Rico’s forest

history at a glance

16

40

38

39

3, 33

3, 32

3, 7

3

Photo by Joel A. Mercado Díaz

Photo by Joel A. Mercado Díaz

35
 ́

0 90

0 5 km

0 10

0 13

0 20

0 69

6 native + 1 introduced

14 native frogs (13

endemic) + 1 introduced

11 native bats + 5

introduced species

1 endemic + 18 natives

11 lizards + 3 geckos (1

introduced) + 5 snakes

61 resident (54 native & 7

introduced) + 46 migratory

7

15

16

19

107

Fish

Amphibians

Mammals

Reptiles

Birds

NUMBER OF

VERTEBRATES SPECIES DESCRIPTION

Number of species

El Yunque National Forest

El Yunque National Forest is home to many plants and animals, including endangered and 

endemic species—species only found in Puerto Rico or the Caribbean region. These maps 

show the species richness of Puerto Rico’s and El Yunque National Forest’s vertebrate land 

animals. Species richness refers to the number of different kinds of animals or plants that 

call a place home. The species richness maps were created by modelling the habitats—

natural home environment—of 202 vertebrate land animals that live in all of Puerto Rico, 

including 18 amphibians, 123 birds, 14 mammals, and 47 reptiles.

FOREST FACT: Snakes are common but rarely seen in El Yunque; the largest is the Puerto Rican Boa, which can 

grow up to 90 inches (2.25 meters). The forest is a wildlife refuge and hunting is not allowed.

El Yunque

harbors 164

vertebrate

species, of

which 157 are

terrestrial and

7 are aquatic.

41

7

41

3

Birds

Reptiles

Amphibians

Mammals

Species richness of vertebrate land animals

Biodiversity

VERTEBRATE ANIMALS

Photo by Gary Potts

36
maricao verde

laurel sabino

cuero de sapo

camasey

palo de cera

chupacallos

hoja menuda

tortugo prieto

palo de jazmín

níspero cimarrón

palo colorado

palo de buey

caracolillo

Luquillo forest lidflower

ortegon

limoncillo

palo de cruz

Woodbury's lidflower

camasey peludo

Ardisia luquillensis mameyuelo

Banara portoricensis

Calyptranthes luquillensis

Calyptranthes woodburyi

Coccoloba rugosa

Conostegia hotteana

Eugenia borinquensis

Garcinia portoricensis

Laplacea portoricensis

Magnolia splendens

Maytenus elongata

Miconia pycnoneura

Morella holdrigeana

Psidium sintenisii

Ravenia urbanii

Symplocos lanata

Ternstroemia luquillensis 

Ternstroemia stahlii

Styrax portoricensis

Pleodendron macranthum

Puerto Rico water-willow

Luquillo mountain clearweed

mountain clearweed

hairy cup orchid

small brachionidium

Carite babyboot orchid

island babyboot orchid

mountain babyboot orchid

Stimson's Lepanthes orchid

Woodbury's babyboot orchid

Puerto Rico babyboot orchid

jazmin de monte 

jazmin portoricensis

beruquillo

Woodbury's nightshade

ortiga

Luquillo mountain manjack

Puerto Rico ridgerunner

guayabota

palo de murta 

palo de candela

camasey

smallstalk necklace fern

Puerto Rico brittleleaf

camasey racimoso

el yunque colorado

saintedwood

Luquillo mountain babyboot orchid

cuero de sapo

uvillo

capa rose

Justicia martinsoniana

Pilea multicaulis

Pilea yunquensis

Brachionidium ciliolatum

Brachionidium parvum

Lepanthes caritensis

Lepanthes dodiana

Lepanthes selenitepala

Lepanthes stimsonii

Lepanthes woodburyana

Lepanthes veleziana

Brunfelsia lactea

Brunfelsia portoricensis

Marlierea sintenisii

Solanum woodburyi

Urera chlorocarpa

Varronia wagnerorum

Cybianthus sintenisii

Eugenia stahlii

Eugenia eggersii 

Xylosma schwaneckeana

Miconia foveolata

Lindsaea stricta

Gonocalyx portoricensis

Miconia pachyphylla

Ternstroemia subsessilis 

Ternstroemia heptasepala 

Lepanthes eltoroensis

Ilex obcordata

Eugenia haematocarpa

Callicarpa ampla

Trees

Vines

Terrestrial plants

Shrubs or small trees

Orchids

Herbs

SCIENTIFIC NAME COMMON NAME

SCIENTIFIC NAME COMMON NAME

El Yunque National Forest has been well studied, but its vast richness in such a small area still has secrets to uncover. In 

2014, 12 new species and two new genera of lichens previously unknown to science were discovered inside El Yunque.

Lichens are symbiotic organisms in which a 

fungus and an alga species, or a fungi and 

cyanobacteria species, associate to form a 

distinct vegetative structure. Symbiosis refers to 

an interdependent relationship between two or 

more organisms. Lichens are commonly found 

on tree trunks and branches, rocks, and on the 

ground but can colonize every type of substrate. 

Lichens grow in many colors and shapes. 

El Yunque National Forest is a complex 

ecosystem that fosters life from a wide range 

of species, from hundreds of tree species 

and over 160 vertebrate species, to nearly 200 

lichens, and thousands of fungi and 

invertebrate species, some of which are 

vulnerable or endangered. A species is 

considered endangered when its individual 

numbers are sufficiently low as to be in 

immediate danger of disappearing completely.

Forest managers identify species for which 

there is substantial concern about their 

capability to persist over the long term in order 

to make management decisions that help 

these species survive; these are called species 

of conservation concern.

El Yunque National Forest

Plant species of conservation concern

LICHENS

45

43, 44

42

42

7, 33

7

7

7

Plants

SPECIES OF CONSERVATION CONCERN

Lichens on a rock

Photo by Joel A. Mercado Díaz

Lichens on a tree trunk

Photo by Joel A. Mercado Díaz

37
Eleutherodactylus eneidae

Eleutherodactylus karlschmidti

Eleutherodactylus unicolor

Eleutherodactylus locustus

Eleutherodactylus richmondi

Eleutherodactylus gryllus

Eleutherodactylus hedricki

Eleutherodactylus portoricensis

Eleutherodactylus wightmanae

Anguilla rostrata

Awaous banana

Dormitor maculatus

Eleotris pisonis

Gobiomorus dormitor

Macrobrachium carcinus

Macrobrachium crenulatum

Accipiter striatus venator

Amazona vittata

Buteo platypterus brunnescens

Falco peregrinus 

Icterus dominicensis

Setophaga angelae

Setophaga caerulescens 

Stenoderma rufum

Anolis cuvieri

Anolis occultus

Chilabothrus inornatus

mottled coquí

web-footed coquí

burrow coquí

warty coquí

ground coquí

cricket coquí

tree-hole coquí

Puerto Rican coquí

wrinkled coquí

American eel

river goby

fat sleeper

spinycheek sleeper

bigmouth sleeper

river shrimp

bocú shrimp

Puerto Rican sharp-shinned hawk

Puerto Rican parrot

broad-winged hawk

peregrine falcon

black-cowled oriole

elfin woods warbler 

black-throated blue warbler 

red fig-eating bat

Puerto Rican giant anole

Puerto Rican pygmy anole

Puerto Rican boa

Reptiles

Mammals

Birds

Aquatic species

Amphibians

SCIENTIFIC NAME COMMON NAME

The coquí tree frogs are an endemic species 

to the island of Puerto Rico. Unlike many 

amphibians, they are born into small adult 

frogs straight from the eggs with no tadpole 

stage within their development. The male 

coquís protect the eggs until several days 

after the frogs hatch.

DID YOU KNOW?

The Puerto Rican parrot, also known as 

Iguaca, was listed as an endangered 

species in 1968. Only an estimated 13 

individuals were living in the wild by 1976. 

In 2015 the Puerto Rico Department of 

Natural and Environmental Resources

reported the parrot population, including 

captive birds in the aviaries, at an 

estimated 500 individuals.

DID YOU KNOW?

El Yunque National Forest

Animal species of conservation concern

7

46

7

7

Animals

SPECIES OF CONSERVATION CONCERN

The Puerto Rican parrot

Amazona vittata

Photo by Jerry Bauer 

Ground coquí

Eleutherodactylus richmondi

Photo by Jerry Bauer 

Ground coquí

Eleutherodactylus richmondi

Photo by Jerry Bauer 

38
“El Yunque is a blessing for Puerto Rico. Its oxygen, clean water, fresh air, recreation areas, flora and fauna are unique in the world. I have the privilege 

of living near and see and delight in its enchantments every day. I hope that people today and future generations take care of the forest, so that we can 

forever enjoy its greatness.” —Richard Washburn, Naguabo community leader

View of the east coast from El Yunque in 1983. Photo by Jerry Bauer

CHAPTER 4—PEOPLE

39
0 5 km

 ́

Finca Shapiro

Finca 

El Verde

Finca Seven Seas

Natural Reserve 

Northeast Ecological Corridor 

Natural Reserve 

Medio Mundo y Daguao

Protected Natural Area

Ceiba

State Forest

Bosque Pterocarpus

Natural Reserve

Río Espíritu Santo

Natural Reserve 

Luz Martínez de

 Benítez Protected

 Natural Area

Las Cabezas de 

San Juan

Natural Reserve 

Finca Colón

Finca Gulín

Conservation

Easement 

Pantano Bosque 

Pterocarpus Lagunas 

Mandry y Santa 

Teresa Humacao

Natural Reserve

Karst Conservation

Zone

Juncos

Las Piedras

Naguabo

Ceiba

Fajardo

Río Grande Luquillo

Canóvanas

0

2000

4000

6000

8000

10 000

12 000

14 000

16 000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

Río Grande Naguabo Luquillo Ceiba Canóvanas Las Piedras Fajardo Juncos

Extent of El Yunque National Forest

Total

municipal

area

Hectares

Acres

El Yunque and other protected areas extent by municipality

According to the U.S. Census Bureau, the population in 

the eight municipalities surrounding the forest totaled 

271,778 persons in 2014, down by more than 6,500 persons 

since 2010. Between 2010 and 2014, Naguabo was the 

only municipality in the region with continued population 

growth (0.16 %/year), while Fajardo and Ceiba saw the 

region’s highest rates of population loss (-1.99%/year, 

-1.88 %/year, respectively). The age structure of the regional 

population also has changed quite dramatically in recent 

years, having exhibited a pyramidal shape indicative of a 

growing population through the end of the 20th century, 

but shifting to a more conical and increasingly top-heavy 

shape by 2014, indicative of a shrinking population as the 

percentage of people in older, post-reproductive age groups 

increases, while those in younger age groups contracts. 

Population in El Yunque region

El Yunque National Forest stretches across eight municipalities 

in northeastern Puerto Rico that total just over 75 270 ha 

(186,000 acres). At 11 540 ha (28,516 acres), El Yunque 

comprises about 15% of their combined area. Other protected 

areas in the region account for 4157 ha (10,273 acres), 5.5% of 

the total area. Together, these municipalities accommodated 

a growing population and an increasing percentage of Puerto 

Rico’s total population through the early 2000s. Yet, following 

an island-wide trend, population growth in the region began 

declining by about 2010 as an increasing number of people 

emigrated off the island, many in response to the economic 

situation, and as birth rates declined (e.g., 1990: 18.87 live 

births/1,000 persons; 2010: 11.34 live births/1,000 persons). 

Other protected areas

El Yunque National Forest

Municipalities

47

47

6

Municipalities and other protected areas

EL YUNQUE REGION

Extent of other protected areas

View of El Yunque National Forest from Las Cabezas de San Juan, Fajardo 

(with the Northeast Ecological Corridor Nature Reserve in the foreground).

Photo by María M. Rivera

40
5% 0 5%

Ceiba

5% 0 5%

Fajardo

5% 0 5%

Luquillo

5% 0 5%

Juncos

5% 0 5%

Las Piedras

5% 0 5%

Canóvanas

5% 0 5%

Naguabo

5% 0 5%

Río Grande

0 5 km  ́

-2.35

-4.76

-6,551

-177,392

271,778

3,548,397

278,329

3,725,789

268,920

3,808,610

235,719

3,522,037

-0.40

-7.51

-7.96

-0.47

-0.01

-3.64

0.62

-3.01

-191

-1,024

-2,944

-188

-4

-730

166

-1,636

36,816

17,145

36,882

30,612

27,896

18,100

22,620

45,648

43,335

18,004

40,712

36,452

34,485

19,817

23,753

52,362

47,648

13,631

36,993

40,290

38,675

20,068

26,720

54,304

47,457

12,607

34,049

40,102

38,671

19,338

26,886

52,668

Canóvanas

Ceiba

Fajardo

Juncos

Las Piedras

Luquillo

Naguabo

Río Grande

1990 2000 2010 2014 %

Puerto Rico

Total region

Net

Total population Change 2010-2014

Population change

5 0 5

0-4

5-9

10-14

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85+

Percentage of population

Age in years

Female Male

5 0 5

0-4

5-9

10-14

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85+

Percentage of population

Age in years

Female Male

Total Population = 268,920

2000

Total Population = 271,778

2014

Population by age and gender

El Yunque region

Distribution and change

POPULATION

47

41
Puerto

Rico

>1,000 500–1,000 <500

Canóvanas

Ceiba

Fajardo

Juncos

Las Piedras

Luquillo

Naguabo

Río Grande

46,563

12,021

36,209

38,995

37,734

18,289

24,481

52,916

1,085

1,610

784

1,295

941

1,779

2,239

1,388

47,648

13,631

36,993

40,290

38,675

20,068

26,720

54,304

3,493,256 232,533 3,725,789

267,208 11,121 278,329

Puerto Rico

Region

Municipalities Urban Rural Total

El Yunque National Forest

Rural population

Urban population

As the population and landscape surrounding El Yunque 

are increasingly urbanized and built up, there is concurrent 

loss of green space, disruption of hydrological systems, 

introduction of nonnative species, and interruption of 

nutrient cycles, which collectively result in changes in the 

benefits and services that forests provide. Between 

1998 and 2010, studies show that built-up areas increased 

by 1334 ha (3,297 acres) in the eight municipalities that 

shelter El Yunque, with Juncos having the highest 

percentage of change.

Urbanization around El Yunque

Juncos urban center to the southwest of El Yunque.

Aerial view from 1998 and 2010.

Population density around El Yunque increased 

throughout much of the 20th century, reaching 

955 persons/mi2 (369 pers./km2) by 2010; ranging 

from 470 pers./mi2 (182 pers./km2) in Ceiba to 

1,521 pers./mi2 (587 pers./km2) in Juncos. Given 

the associated density in residential, commercial, 

and other built-up areas, 96% of the regional 

population was classified as “urban” by the U.S. 

Census Bureau in 2010, up from 37% in 1970. 

With decreases in the population around El 

Yunque since about 2010, population densities 

have decreased as well, but remain among the 

highest in the world. For example, while the 

lowest in the region, Ceiba’s population density 

in 2010 still ranked higher than two thirds of the 

world’s sovereign nations.

(persons per square mile)

Population density in 2010

Urban and rural population in 2010

7

50

49, 14

47

47

48

47

Density and urbanization

POPULATION

1998

2010

42
$

$ $

$

$

$

$

$

>$20,000

$17,000–$20,000

$ <$17,000

$

$ 15–18%

18–21%

11–15%

Río GrandeCanóvanas

Fajardo Juncos Las Piedras

Naguabo Luquillo Ceiba

0

5,000

10,000

15,000

20,000

25,000

Total

housing

units

Vacant houses

Occupied houses

Puerto Rico $10,355 $18,791 16.7% 45.2% 56.3%

Canóvanas

Ceiba

Fajardo

Juncos

Las Piedras

Luquillo

Naguabo

Río Grande

$9,852

$9,658

$9,949

$8,968

$9,078

$10,506

$7,548

$10,049

$21,934

$18,461

$19,803

$17,694

$17,680

$19,672

$15,250

$20,850

15.3%

11.7%

17.6%

15.9%

18.6%

21%

15.4%

19.3%

42.5%

43.1%

42.1%

47.3%

47.5%

44.9%

52.6%

42.1%

52.6%

52.6%

54.6%

55.6%

56.6%

63.5%

64.7%

53.3%

Children 

(<18 yrs)

living below

poverty level

Total

population

living below

poverty level

Unemployed

civilian

labor force

Median

household

income

Per capita

Municipalities income

In 2010, the majority of jobs in the region were in “education, health, and social services” (21%), followed by “retail 

trade” (13%), “manufacturing” (12%) and “arts, entertainment, recreation, and accommodations” (10%), all of which 

increased over the 2000 U.S. Census rates, except manufacturing, which declined by 3%.

Per capita income in the municipalities 

surrounding El Yunque ranged from $7,548 in 

Naguabo to $10,506 in Luquillo in 2010. Median 

household income ranged from $15,250 in 

Naguabo to $21,934 in Canóvanas. Unemployment in the civilian labor force was about 17% 

in 2010. However, the percentage of the 

population actively seeking employment that 

year was significantly lower than in the United 

States (48% vs. 65%). Income, employment, 

and many other socioeconomic factors have 

been influenced by the economic crisis 

affecting Puerto Rico since the mid-2000s. 

In 2010, about 44% of the regional population 

was living below the poverty level as defined 

by the U.S. Census Bureau. Fairly significant 

intraregional differences existed, with Fajardo 

and Río Grande having the lowest poverty 

rates (42%), while Naguabo had the highest 

poverty rate (53%). In 2010, children (younger 

than 18) made up a disproportionate share of 

the poor, representing less than 25% of the 

total regional population, but more than 33% 

of those living in poverty. 

47 51

7

47

Income and unemployment in 2010 Occupied and vacant housing units in 2010

Median household income in 2010 Unemployment rate in 2010

Income, unemployment, and housing in El Yunque region

SOCIOECONOMIC STATISTICS

43
44
CHAPTER 5—RESEARCH AND MANAGEMENT

“El Yunque National Forest is a truly dynamic 

ecosystem where each visit to the field has the 

potential for adventure, memorable stories, discovery, 

and physical and mental awareness. The benefits we 

receive by visiting the Luquillo forest over the long 

term never get old or wasted as the landscape and 

the experiences are always changing.”

—Grizelle González, research project leader, 

USDA Forest Service

Photo by Joel A. Mercado Díaz 

María M. Rivera, Biologist Specialist

45
"

"" "

"

"

"

"

"

" " "

""

" "

" "

"

"

"

""

" "

"

"""

"

"

"

"

""

"" "

"

"

" "

"

"

""

"

" " "

" "

"

" " "

"" "

""

"

"

"

"

"

"

"

"

"

" "

"

""

6

5

3

7

2

" "

"8

"

"

9

1

4

"

10

12

11

13

0 3 km

 ́

4

1

0 0.5 km 0 0.5 km

Managed by the U.S. Fish and Wildlife Service, the Iguaca 

Aviary sits on half a hectare (1.2 acres) of land at 550 m 

elevation since 1972. It is one of two aviaries in Puerto Rico 

that house the endangered Puerto Rican parrot (Amazona 

vittata). Its breeding program has enabled the transfer of 

Puerto Rican parrots back into the wild and between 

aviaries, increasing both the wild and aviary populations.

Since the 1980s, two adjacent watersheds totaling 

13 ha (32 acres) in the northern part of the forest were 

designated as Long-Term Experimental Watersheds for 

the study of climate, water resources, nutrient cycling, 

flora, and fauna. Ozone monitoring in the site started in 

2008. The site has two walk-up canopy towers, climate 

stations, three stream gages, throughfall and litter 

collectors, permanent ecological study plots, and 

areas designated for aquatic research.

Scientific research in El Verde began in the 1940s, 

focusing on forest dynamics, and later in the 1960s 

on stream ecology, hydrology, and ecosystem 

processes. Most current research is conducted by 

the Luquillo Long-Term Ecological Research program. 

Some of the facilities were constructed in the 1930s 

and are considered of historic value. In 1990, the 

Luquillo Forest Dynamics Plot was established 

near El Verde Station, covering 16 ha (39.5 acres), 

with elevations from 333 to 428 m.

The station is located at 265 m in elevation within a 

small community on the outskirts of the forest near the 

Bisley Experimental Watersheds. It holds facilities for 

water analyses and a mycology—the study of fungi—

laboratory, plus living quarters for visiting researchers. 

Sabana

Field

Research

Station

El Verde

Research

Station

and

Luquillo

Forest

Dynamics

Plot

Iguaca

Aviary

Bisley

Experimental

Watersheds

STATION DESCRIPTION

El Verde Research Area Bisley Experimental Watersheds

El Yunque National Forest is a living research laboratory. Designated the 

Luquillo Experimental Forest in 1956, it has provided an array of useful 

information on local climate, geology, soils, water resources, flora, fauna, and 

ecology for over a century. In 1988, the National Science Foundation began 

the Long Term Ecological Research Program and established long-term 

research sites in the forest. Today, over 1,000 scientific publications have been 

written based on the research done in El Yunque.

3, 7, 52

32

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

Bisley Experimental Watersheds

Caracoles Arboretum

Catalina

El Verde Field Research Station

Guzmán plantation

Harvey plantation

Iguaca Aviary

Pico del Este

Pico del Oeste

Río Grande 3

Sabana 4

Sabana 8

Sabana Field

Research Station

Main research sites Research areas

"

Proclamation area

Closed road

Roads

Trails

Research plots

Luquillo Experimental Forest

Luquillo Forest Dynamic Plot

El Verde Research Area

Bisley Experimental Watersheds

Sites and plot network

RESEARCH

Photo by Joel A. Mercado Díaz

46
Description and management

DESIGNATED AREAS

Río Mameyes

Río La Mina

Río Icacos Scenic 2.3 miles (3.7 km)

Recreation 0.9 miles (1.4 km)

Scenic 1.2 miles (1.9 km)

Recreation 1.0 miles (1.6 km)

Scenic 1.4 miles (2.3 km)

Wild 1.6 miles (2.6 km)

RIVER CLASSIFICATION LENGTH

FOREST FACT

Wild & Scenic Rivers

Designated areas

Río La Mina

Río Mameyes

Río Icacos

El Toro Wilderness

Baño de Oro

Forest boundary

Rivers

Proclamation area

Proclamation Area (1950)

Wild and Scenic Rivers (2002)

El Toro Wilderness Area (2005)

Baño de Oro Research Natural Area (1949)

The proclamation area is a legal delimitation. 

The USDA Forest Service is permitted to buy 

land inside this area to incorporate into the 

El Yunque National Forest.

The U.S. Congress designated portions of the rivers Río 

Mameyes, Río de la Mina, and Río Icacos as National Wild and 

Scenic Rivers in 2002 for their unique scenic, recreational, 

geologic, fish and wildlife, historic, and cultural values. These 

are the only tropical rivers in the National Wild and Scenic River 

System. Portions of the rivers under this designation are 

classified as wild, scenic, or recreational, each with its own level 

of protection, but in general preserving them in their natural freeflowing condition, and accessible mostly by trail. The zones 

around the rivers are also protected, kept in primitive condition, 

free of structures or modifications of the landscape. They serve 

as undisturbed habitat for many species.

Federal research natural areas are predominantly natural tracts of land 

with little human influence, preserved for scientific and educational 

purposes. Designated in 1949, this area covers 745 ha (1,841 acres). This 

area is one of the wettest in the forest and provides habitat for at least 40 

bird species. Total relief is 780 m, ranging from 245 m along the Mameyes 

River in the north to 1025 m in Pico del Oeste in the south.

54

3

7

3

53

In 1976, the entire El Yunque 

National Forest was declared 

the Luquillo Experimental Forest 

Biosphere Reserve. Biosphere 

Reserves are internationally 

recognized protected areas 

managed to promote biodiversity 

conservation and sustainable 

uses. The reserves are nominated by local governments to the 

United Nations Educational, 

Scientific, and Cultural 

Organization (UNESCO).

Designated by the U.S. Congress as a wilderness 

area in 2005 under the Wilderness Act of 1964, El Toro 

Wilderness Area is the largest undisturbed stretch of 

land in Puerto Rico, measuring over 4150 ha (10,254 

acres). Wilderness refers to land with minimal impact 

from human activity that remains in its original “wild” 

state. The Wilderness Act aims to conserve the 

primeval character and influence of these areas for 

public enjoyment in perpetuity. Named after the 

highest peak in the Luquillo Mountains, elevations 

here range from 370 m to 1074 m; the headwaters of 

10 streams that supply water to surrounding 

communities flow from its peaks. Photo by Jerry Bauer

Photo by Jerry Bauer

47
£¤

£¤

£¤

£¤

£¤

£¤

 ́

17

16

8

7

6

4

3

2

1

990

988

191

186

FS27

9966

Trails

Closed road

Roads

Proclamation area

!i

!i

!i!i

!i

!i

!=

!=

!=

!A

!=

!=

!=

!=

!=

!A

!A

!=!=!=!=

!° !°

!A

0 2 km

!i

!°

!A

!

!=

Closed gate

Parking lot

Research

facility

Observation

tower

Building

Communication

tower

A section of road PR-191 in the south side of the forest has been closed 

since a landslide destroyed it in 1981.

The forest infrastructure supports recreation, communications, 

water supply, research, resource management, and access 

to the forest.

Constructed in the 1930s, the road system that runs through the forest allows access to resources 

and communication sites and is essential for recreational, administrative, and research uses. There 

are about 33 miles (53 km) of roads within the forest. Intense maintenance is needed on many of 

the roads because of weather conditions in the Luquillo Mountains. Gates on some roads control 

vehicular access according to road conditions or to limit use for official business and rescue efforts. 

The forest has a total of 454 parking spaces. There are 18.8 miles (30 km) of recreational trails and 

12 miles (19 km) of administrative trails. All trails are restricted to foot traffic (hiking) only. Horses, 

motorcycles, and mountain bikes are not allowed within the forest.

7

INFRASTRUCTURE

Roads and buildings

El Portal Visitor Center, Photo by Jerry Bauer

48
!i

!i

!i

!i

!i

!A

!=

!A

!A

!=!=

!=

!=

!A

13

14

15

11

5

1

10

2

9

Research facilities

Observation towers

Label Buildings

El Yunque tower

Mount Britton tower

Yokahú tower

El Verde Field Station

Sabana Field Research Station

Catalina (FS Headquarters)

Cienaga Alta house

Eliza Colberg Camp

El Portal Visitors Center

El Yunque Pavilion

Iguaca Aviary

Job Corps Camp

La Condesa School

La Mina barracks and old aviary

La Mina fish hatchery

Molindero cottages

Stone house

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

The International Institute of Tropical Forestry is a USDA Forest Service research 

development and technology transfer institute located in Río Piedras, Puerto Rico. 

Created in 1939 in cooperation with the University of Puerto Rico, the Institute has 

long been a leader in tropical forestry research, technology transfer, and technical 

assistance throughout the world. Through its research the Institute has contributed 

invaluable information about El Yunque National Forest. The mission of the 

Institute includes to develop and disseminate knowledge that contributes to the 

conservation of tropical forests, wildlife, and watersheds.

INTERNATIONAL INSTITUTE OF TROPICAL FORESTRY

International Institute of Tropical Forestry

Photo by Maya Quiñones

Sabana Field Research Station

Photo by Carlos Estrada

El Verde Field Research Station

Photo by Gary Potts

Communication tower

Photo by Carl Baker

49
50
CHAPTER 6—RECREATION

“El Yunque gave me the opportunity of feeling fulfilled, 

through my long walks and pouring rain while we 

evaluated the forest’s condition and during the 

preparation of the land for the planting of mahogany 

trees. I will not deny that in many occasions I was 

mesmerized with the sights and sounds of the 

forest during these experiences, memories that will 

accompany me until my last days.”

—Luis A. Rivera, retired El Yunque forester 

and tropical vegetation specialist

Photo by Gary Potts

51
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Rainy season

Hurricane season

El Portal closed for

annual maintenance High visitation period High visitation period

@ElYunqueNF

The forest is closed on the 25th of December and El Portal Visitors Center closes for annual 

maintenance and repairs for two weeks in September. The forest may be closed for safety 

reasons and to ensure the welfare of its visitors, but these closures tend to be of short 

duration and only happen sporadically during the year. Flash floods and hurricanes are 

important weather events that can cause dangerous conditions in the forest. These events 

are closely monitored and the forest is closed when conditions become dangerous or when 

Puerto Rico is under a tropical storm or hurricane watch or warning. Flash flood events are 

more common during the forest's rainy season from August through November, while the 

hurricane season runs from June 1st to November 30th. 

TEMPORARY CLOSURES

Opens daily from 7:30 a.m. to 6:00 p.m.

Telephone: (787) 888-1880

Website: https://www.fs.usda.gov/elyunque

Enjoying nature is one of the most satisfying recreational activities to connect 

people with their natural environment. There are few places that can be 

compared with a tropical rainforest. It's no wonder why people want to protect 

and enjoy such a special place. With over 600,000 visitors and 1.1 million site 

visits a year, El Yunque National Forest offers numerous recreation 

opportunities like hiking trails, guided tours, a visitor center, sheltered picnic 

areas, and lookout towers. The recreation opportunities provided by the 

forest’s picnic areas, scenic vistas, trails, and streams continue to be scarce 

and valuable resources to both local and international visitors. 

Opening hours and closures

RECREATION

La Coca Falls

Photo by Luis Andrei Muñoz

52
0 3 km

 ́

Landslide

ElToroTrail

Río SabanaTrail

Río Icacos

Río

Mameyes

Río de la Mina

TradeWindsTrail

£¤9966

£¤FS27

£¤FS10

£¤186 £¤988

£¤191

Trails Roads Closed road Wild and Scenic rivers Rivers Recreation areas

To protect the biodiversity and natural richness that make 

El Yunque National Forest special, hunting and fishing 

activities are forbidden within the forest, and no trails 

are available for off-road vehicles or horseback riding. 

Bicycles are allowed only on paved roads. Along the 

Wild and Scenic rivers, no cooking or sound equipment 

is allowed. Visitors are asked to “Leave No Trace” and 

to pack out all trash when they leave the forest.

Protect the forest

The visitor and information centers and most trailheads, vista points, 

and observation towers are located along road PR-191, which runs 

north to south and ends at a closed gate beyond which only pedestrian 

access is permitted. Other recreation opportunities, mostly used by 

the local community, are found outside the main recreation corridor. 

These include the Puente Roto River crossing and trailheads along 

PR-988, PR-186 to the west, and PR-191 on the south side of the 

forest, where the Río Sabana trailhead and picnic area are located.

RECREATION

Roads, trails, and recreation areas

Yucahú Tower

Photo by Sonja Baker

Vista from Yocahú Tower

Photo by Carl Baker

53
El Portal Visitor Center, constructed in 1996, was especially 

designed to integrate into the surrounding forest landscape 

with minimal impact. El Portal houses a theater where an 

orientation film is featured, an information desk, souvenir store, 

food stand, and interactive interpretive exhibits. Currently, as 

this publication goes to press, the entrance cost to El Portal 

is $4 for adults (16 to 59 years), $2 for seniors (over 60 years), 

and free for anyone under 15 years. No fees are currently 

charged for entrance to any of the other facilities in the forest.

El Portal Visitor Center

The main entrance of El Yunque National Forest is located on road 

PR-191 travelling from the north, followed by the El Portal Visitor 

Center, numerous hiking trails, and parking and picnic areas. Signs 

at each trailhead show the difficulty level of each trail. The Palo 

Colorado Visitor Center is located near the end of the road with 

parking, picnic areas, various trailheads nearby, and an information 

desk. A gate marks the end of the road, beyond which only 

pedestrian access is allowed.

El Portal Visitor Center

Photo by Jerry Bauer

7

along PR-191

RECREATION CORRIDOR

!i

q!

!m

!m

!m

 ̧ =! Palo 

Colorado

 ̧=!

El Portal

 ́

0 1 km

¤

¤

¤

£¤

£¤

£¤ £¤

£¤

£¤

£¤

9966 988

990

191

FS10

FS27

930

 ̧

!q

!m

=!

Puente Roto river crossing

Waterfall

Mountain peak

Visitor center

Picnic area

Observation tower

Food stand

Bathrooms

Parking

Wild and scenic rivers

Trails

Rivers

Roads

Closed gate

Information

Mt. Britton Spur

Mt. Britton Trail

Río Icacos

Río Mameyes

Río de la Mina

Angelito Trail

La Coca Trail

Big Tree Trail

La Mina 

Trail

Sierra Palm

Picnic Area

Caimitillo

Trail

Los Picachos Trail

El Yunque Trail

oñaB de Oro

Mt. Britton Trail

Mt. Britton Spur

Trade Winds Trail

El Portal Visitor Center

Photo by Jerry Bauer

54
difficult

difficult

easy

difficult

moderate

difficult

moderate

difficult

easy

difficult

moderate*

moderate*

difficult

2.3 miles (3.8 km)

2.2 miles (3.6 km)

0.2 miles (0.4 km)

1.8 miles (2.9 km)

0.9 miles (1.4 km)

0.7 miles (1.1 km)

0.4 miles (0.6 km)

2.6 miles (4.2 km)

0.3 miles (0.5 km)

0.8 miles (1.3 km)

0.3 miles (0.5 km)

0.2 miles (0.3 km)

4.3 miles (6.9 km)

El Toro

Río Sabana

Angelito

La Coca

Big Tree

La Mina

Caimitillo

El Yunque

Baño de Oro

Mount Britton

Mount Britton Spur

Los Picachos

Tradewinds

*Trailhead only accessible through other trails with different difficulty levels.

Trailheads inside the Recreation Corridor along PR-191

Trailheads outside the Recreation Corridor

Trail name Length (one way) Diculty level

There are no camping facilities in the forest. 

However, primitive camping is allowed by 

special permit. Primitive camping refers to 

camping in wild natural areas with no facilities or 

infrastructure. Special permit forms should be 

submitted at least two weeks in advance. The 

camping permit and the El Yunque National 

Forest camping policies can be found at 

http://www.fs.usda.gov/elyunque 

Camping in El Yunque

Hiking trails in El Yunque vary 

in length and difficulty. The 

difficulty level is generally based 

on the trail width, surface and 

condition, steepness of grades, 

gain and loss of elevation, 

and the amount and kinds of 

natural barriers that may be 

encountered during the hike.

Supplies like food and water 

should be taken along, 

especially on longer trails. 

There are no kiosks or vending 

machines on the trails.

Many trails lead to beautiful 

waterfalls and hidden ponds, 

like the Big Tree Trail, Angelito 

Trail, and La Coca Trail, and to 

breathtaking vistas from atop 

the mountains, like El Toro Trail, 

Tradewinds Trail, El Yunque 

Trail, and Los Picachos Trail. 55

7

El Yunque Hiking Trails

Photo by Joe Baker

Bird watching in Mount Britton Trail

Photo by Gary Potts

55
Photo by Gary Potts

Photo by Gary Potts

Photo by Maya Quiñones

56
References

1. U.S. Department of Agriculture, Forest Service. [N.d.]. Centennial 

timeline summary. https://www.fs.usda.gov/detail/elyunque/aboutforest/?cid=fsbdev3_042983. (25 November 2014).

2. Daly, C.; Helmer, E.H.; Quiñones, M. 2003. Mapping the climate of Puerto 

Rico, Vieques and Culebra. International Journal of Climatology. 23: 

1359–1381.

3. Weaver, P. L. 2012. The Luquillo Mountains: forest resources and their 

history. Gen. Tech. Rep. IITF-44. Río Piedras, PR: U.S. Department of 

Agriculture Forest Service, International Institute of Tropical Forestry. 159 p.

4. Miller, G.L.; Lugo, A.E. 2009. Guide to the ecological systems of Puerto 

Rico. Gen. Tech. Rep. IITF-GTR-35. Río Piedras, PR: U.S. Department of 

Agriculture, Forest Service, International Institute of Tropical Forestry. 437 p.

5. Bosworth, D. 2003. El Yunque: a century of leading the way. El Yunque, 

Puerto Rico. https://www.fs.fed.us/speeches/el-yunque-century-leadingway. (24 June 2016).

6. Caribbean Landscape Conservation Cooperative Protected Areas 

Conservation Action Team. 2015. Puerto Rico protected areas database. 

December 2015 version [GIS data]. San Juan, PR. http://caribbeanlcc.org/

puerto-rico-protected-areas-cat-data-download/. (23 June 2016).

7. U.S. Department of Agriculture, Forest Service. 2014. Forest 

plan assessment. Río Grande, PR: El Yunque National Forest. 

https://www.fs.usda.gov/detail/elyunque/landmanagement/

planning/?cid=stelprdb5411336. (23 June 2016).

8. Álvarez Nazario, M. 1977. El influjo indígena en el español de Puerto Rico. 

San Juan, Puerto Rico: La Editorial de la Universidad de Puerto Rico. 191 p.

9. De Guillerna y de las Heras, C. 1885. Informes sobre Montería Forestal. 

Archivo General de Puerto Rico. Fondo: Obras Públicas. Serie: Propiedad 

Pública. Caja 315.

10. Quiñones, M.; Gould, W.A.; Castro-Prieto, J.; Martinuzzi, S. 2013. Spatial 

analysis of Puerto Rico’s terrestrial protected areas. [1:240 000] IITFRMAP-03. Río Piedras, PR: U.S. Department of Agriculture, Forest Service, 

International Institute of Tropical Forestry.

11. Hassan, R.; Scholes, R.; Ash, N., eds., 2005. Ecosystems and human wellbeing: current state and trends. Vol. 1. Washington, DC: Island Press. 23 p.

12. López-Marrero, T.; Hermansen-Báez, L.A. 2011. El Yunque Ecosystem 

Services: A Participatory Research Approach. [Fact sheet]. Gainesville, FL. 

USDA Forest Service, Southern Research Station. 4 p.

13. González, G.; Willig, M.R.; Waide, R.B., eds. 2013. Ecological gradient 

analyses in a tropical landscape. Ecological Bulletin 54: 13–20. 

14. U.S. Army Corps of Engineers. 2010. Puerto Rico 2010 digital orthophotos 

[Aerial photographs]. St. Louis, MO.

15. Martinuzzi, S.; Gould, W.A.; Ramos González, O.M.; Edwards, B.E. 2007. 

Development of a Landforms Model for Puerto Rico and its Application for 

Land Cover Change Analysis. Caribbean Journal of Science. 43(2): 161-171.

16. Lugo, A.E. 1994. Preservation of primary forests in the Luquillo Mountains, 

Puerto Rico. Conservation Biology. 8(4): 1122–1131.

17. Bawiec, W.J., ed. 1999. Geology, geochemistry, geophysics, mineral 

occurrences and mineral resource assessment for the Commonwealth of 

Puerto Rico. Open-File Report 98-038. Reston, VA: U.S. Department of the 

Interior, Geological Survey. https://pubs.usgs.gov/of/1998/of98-038/. (23 

June 2016).

57
18. Nauman, R.; Dangermond, M.; Frye, C. 2015. Esri’s SSURGO 2014 

map units for the eastern Puerto Rico Subbasin. SSURGO Downloader 

2014. ESRI Application. https://www.arcgis.com/home/item.

html?id=4dbfecc52f1442eeb368c435251591ec. (8 February 2016).

19. Mount, H.R.; Lynn, W.C. 2004. Soil survey laboratory data and soil 

descriptions for Puerto Rico and the U.S. Virgin Islands. Soil Survey 

Investigations Report No. 49. Lincoln, NE: U.S. Department of Agriculture, 

Natural Resources Conservation Service, National Soil Survey Center. 706 

p.

20. Soil Survey Staff. 1999. Soil taxonomy: a basic system of soil classification 

for making and interpreting soil surveys. 2nd ed. Agric. Handb. 436. 

Washington, DC: U.S. Department of Agriculture, Natural Resources 

Conservation Service. 886 p.

21. Ping, C.L.; Michaelson, G.J.; Stiles, C.A.; González, G. 2013. Soil 

characteristics, carbon stores, and nutrient distribution in eight forest types 

along and elevation gradient, eastern Puerto Rico. Ecological Bulletins. 54: 

67–86.

22. Soil Survey Staff. 2016. Web soil survey [Database]. Washington, DC: 

U.S. Department of Agriculture, Natural Resources Conservation Service. 

https://websoilsurvey.nrcs.usda.gov/. (March 2016).

23. Stallard, R.F. 2012. Atmospheric inputs to watersheds of the Luquillo 

Mountains in Eastern Puerto Rico. In: Murphy, S.F.; Stallard, R.F., eds. Water 

quality and landscape processes of four watersheds in eastern Puerto 

Rico. Professional Paper 1789. Reston, VA: U.S. Department of the Interior, 

Geological Survey: 89–112. 

24. McClintock, M.A.; Brocard, G.; Willenbring, J.; Tamayo, C.; Porder. 

S.; Pett-Ridge, J.C. 2015. Spatial variability of African dust in soils in a 

montane tropical landscape in Puerto Rico. Chemical Geology. 412: 69–81.

25. U.S. Geological Survey. 2014. Landsat 8 OLI Image, Path 4 Row 47 July 

29th 2014 [Satellite Image]. Sioux Falls, SD. https://earthexplorer.usgs.gov/. 

(3 April 2015).

26. López-Marrero, T.; Hermansen-Báez, L.A. 2011. Land cover within and 

around El Yunque National Forest. [Fact sheet]. Gainesville, FL: U.S. 

Department of Agriculture, Forest Service, Southern Research Station. 4 p.

27. U.S. Geological Survey in cooperation with the U.S. Department of 

Agriculture, Natural Resources Conservation Service. 2002. Hydrologic 

unit boundaries for Puerto Rico [GIS data]. Shapefile format. San Juan, PR. 

https://datagateway.nrcs.usda.gov/. (29 April 2014).

28. Ahmad, R; Scatena, F.N.; Gupta, A. 1993. Morphology and sedimentation 

in Caribbean montane streams: examples from Jamaica and Puerto Rico. 

Sedimetary Geology. 85: 157–169.

29. Heartsill Scalley, T.; López-Marrero, T. 2014. Land-cover composition, 

water resources and land management in the watersheds of the Luquillo 

Mountains, northeastern Puerto Rico. Caribbean Geography. 19: 43–68.

30. Crook, K.E.; Scatena, F.N.; Pringle, C.M. 2007. Water withdrawn from 

the Luquillo Experimental Forest, 2004. IITF-GTR-34. Río Piedras, PR: U.S. 

Department of Agriculture, Forest Service, International Institute of Tropical 

Forestry. 26 p.

31. Barber, N.L. 2014. Summary of estimated water use in the United States 

in 2010. Fact Sheet 2014–3109. Reston, VA: U.S. Department of the Interior, 

Geological Survey. 2 p.

32. Harris, NL.; Lugo, A.E.; Brown, S.; Heartsill Scalley, T., eds. 2012.

Luquillo Experimental Forest: research history and opportunities. EFR-1. 

Washington, DC: U.S. Department of Agriculture, Forest Service. 152 p.

33. Weaver, P.L.; Gould, W.A. 2013. Forest vegetation along environmental 

gradients in northeastern Puerto Rico. Ecological Bulletins. 54: 43–65.

34. Waide, R.B.; Comarazamy, D.E.; González, J.E.; Hall, C.A.S.; Lugo, A.E.; 

Luvall, J.C.; Murphy, D.J.; Ortiz-Zayas, J.R.; Ramírez-Beltran, N.D.; 

Scatena, F.N.; Silver, W.L. 2013. Climate variability at multiple spatial 

and temporal scales in the Luquillo Mountains, Puerto Rico. Ecological 

Bulletins. 54: 21–41.

58
35. Henareh Khalyani, A.; Gould, W.A.; Harmsen, E.; Terando, A.; Quiñones, 

M.; Collazo, J.A. 2016. Climate change implications for tropical islands: 

interpolating and interpreting statistically downscaled GCM projections 

for management and planning. Journal of Applied Meteorology and 

Climatology. 55: 265–282.

36. Lugo, A.E. 2009. The emerging era of novel tropical forests. Biotropica. 

41(5): 589–591.

37. Ewel, J.J.; Whitmore J.L. 1973. The ecological life zones of Puerto Rico 

and the U.S. Virgin Islands. Res. Pap. No. ITF-18. Rio Piedras, PR: U.S. 

Department of Agriculture, Forest Service, International Institute of Tropical 

Forestry. 72 p.

38. Birdsey, RA.; Weaver, PL. 1982. The forest resources of Puerto Rico. 

Resour. Bull. SO-85. New Orleans, LA: U.S. Department of Agriculture, 

Forest Service, Southern Forest Experiment Station. 65 p.

39. Domínguez Cristóbal, C.M. 2000. Panorama Histórico Forestal de Puerto 

Rico. San Juan, PR: La Editorial de la Universidad de Puerto Rico. 680 p.

40. Brandeis, T.J.; Turner, J.A. 2013. Puerto Rico’s Forests, 2009. Resour. Bull 

SRS-191. Asheville, NC: U.S. Department of Agriculture Forest Service, 

Southern Research Station. 85 p.

41. Gould, W.A.; Alarcón, C.; Fevold, B.; Jiménez, M.E.; Martinuzzi, S.; Potts, 

G.; Quiñones, M.; Solórzano, M.; Ventosa, E. 2008. The Puerto Rico Gap 

Analysis Project. Volume 1: Land cover, vertebrate species distributions, 

and land stewardship. Gen. Tech. Rep. IITF-GTR-39. Río Piedras, PR: U.S. 

Department of Agriculture, Forest Service, International Institute of Tropical 

Forestry. 165 p.

42. Mercado-Díaz, J.A.; Gould, W.A.; González, G.; Lücking, R. 2015. Lichens 

in Puerto Rico: an ecosystem approach. Gen. Tech. Rep. IITF-GTR-46. San 

Juan, PR: U.S. Department of Agriculture, Forest Service, International 

Institute of Tropical Forestry. 90 p.

43. Cantrell, S.A.; Lodge, J.D.; Cruz, C.A.; García, L.M.; Pérez-Jiménez, J.R.; 

Molina, M. 2013. Differential abundance of microbial functional groups 

along the elevation gradient from the coast to the Luquillo Mountains. 

Ecological Bulletins. 54: 87–100.

44. Richardson B.A.; Richardson, M.J. 2013. Litter-based invertebrate 

communities in forest floor and bromeliad microcosm along an elevational 

gradient in Puerto Rico. Ecological Bulletins. 54: 101–115

45. Mercado-Díaz, J.A.; Lücking, R.; Parnmen, S. 2014. Two new genera and 

twelve new species of Graphidaceae from Puerto Rico: a case for higher 

endemism of lichenized fungi in islands of the Caribbean. Phytotaxa. 189 

(1): 186–203.

46. Quiles, C.D.M. 2015. Bosque estatal de Maricao recibe grupo de cotorras 

puertorriqueñas. El Nuevo Día. (August 13). http://www.elnuevodia.com/

ciencia/ciencia/nota/bosqueestataldemaricaorecibegrupodecotorraspuertorriquenas-2086118/. (1 February 2016).

47. U.S. Department of Commerce, Census Bureau. 2016. American fact 

finder [Database]. Washington, DC: American Community Survey Office. 

https://factfinder.census.gov/. (4 March 2016).

48. United Nations. 2013. World population prospects: the 2012 revision. New 

York: Department of Economic and Social Affairs, Population Division.

49. Centro de Recaudación de Ingresos Municipales de Puerto Rico. 1998.

Fotos aéreas de Puerto Rico del 1998. [Aerial photographs]. San Juan, PR. 

50. López-Marrero, T.; Hermansen-Báez, L.A. 2011. Expansion of urban land 

cover around El Yunque National Forest. [Fact sheet]. Gainesville, FL: U.S. 

Department of Agriculture, Forest Service, Southern Research Station. 4 p.

51. U.S. Department of Commerce, Census Bureau. 2012. Puerto Rico: 2010, 

Summary Population and Housing Characteristics. CPH-1-53. New York: 

475 p.

52. Earnhardt, J.; Valentin-Velez, J.; Valentin, R.; Long, A.; Lynch, C.; Schowe, 

K. 2014. The Puerto Rican parrot reintroduction program: sustainable 

management of the aviary population. Zoo Biology. 33(2): 89–98.

59
53. U.S. Department of Agriculture, Forest Service. [N.d.]. Wild and 

Scenic Rivers and proposed wilderness area. Rio Grande, PR: El 

Yunque National Forest. https://www.fs.usda.gov/detailfull/elyunque/

home/%3Fcid%3Dfsbdev3_042977. (23 June 2016).

54. Cruz, P. 2010. Caribbean National Forest Wild and Scenic Rivers 

comprehensive river management plan. Atlanta, GA: U.S. Department of 

Agriculture, Forest Service, Southern Region. 50 p.

55. Puerto Rico Day Trips. 2008. Hike the El Yunque Trail to the Top of the rain 

forest. http://www.puertoricodaytrips.com/hike-the-el-yunque-trail/. (4 May 

2014).

56. Convention on Biological Diversity. [N.d.]. Article 2: use of terms. 

Montreal, Quebec, Canada. https://www.cbd.int/convention/articles/

default.shtml?a=cbd-02. (24 July 2015).

57. The Wilderness Act of 1964. Public Law 88-577 (16 U.S. C. 1131-1136).

60
Glossary

Alluvium—Sediment deposits of sand, gravel, and clay product of flowing water.

Anthropogenic—Caused or produced by human activity.

Aviary—A large enclosure to hold birds. 

Biodiversity—The Convention on Biological Diversity, established by the United 

Nations, defines biodiversity as “the variability among living organisms from all 

sources including, inter alia, terrestrial, marine and other aquatic ecosystems 

and the ecological complexes of which they are a part; this includes diversity 

within species, between species, and of ecosystems.” 56

Biogenic—The product of living organisms.

Endemic—Refers to species that are unique to a geographical area.

Endangered species—Species in immediate danger of disappearing 

completely—becoming extinct.

Fault breccia—Rocks formed by tectonic forces from broken fragments of 

minerals and other rocks.

Habitat—A place where a species lives.

Hydric soils—The National Technical Committee for Hydric Soils (NTCHS) 

defines hydric soils as “soils that formed under conditions of saturation, 

flooding, or ponding long enough during the growing season to develop 

anaerobic conditions in the upper part (Federal Register 1994). These soils, 

under natural conditions, are either saturated or inundated long enough 

during the growing season to support the growth and reproduction of 

hydrophytic vegetation.” 22

Hydrophytic plants—Plants adapted to aquatic conditions.

Intrusive rocks—Igneous rocks made of hardened magma that form below the 

surface.

Ecosystem—The Convention on Biological Diversity defines ecosystem as “a 

dynamic complex of plant, animal, and micro-organism communities and their 

non-living environment interacting as a functional unit.” 56

Ecosystem services—Benefits that humans obtain from nature.

Land cover—The physical material on top of the Earth’s surface.

Landforms—Shapes that describe the topography of the Earth’s surface.

Life zones—Broad bioclimatic units that bear a close relationship to natural 

and biologically meaningful landscapes. These were developed using the 

Holdridge model, in which precipitation and biotemperature data are used 

to delineate the zones, which are then classified based on latitudinal region, 

altitudinal belt, and humidity province.37

Lichens—Symbiotic organisms composed of both fungi and algae, or fungi and 

cyanobacteria.

Municipality—A political administrative subdivision used in Puerto Rico.

Mycology—The study of fungi or mushrooms, yeasts, and molds.

Primary forest—Forest that has not been anthropologically disturbed and has 

kept its original natural vegetation structure and species composition. Also 

called virgin forest. 

Ravine—Steep-sided valley smaller than a canyon, typically the result of erosion 

by running water.

61
Riparian—Related to rivers and their immediate surroundings.

Secondary forest—Forest areas that have regrown after significant removal of 

its original vegetation so as to alter its original species composition.

Silviculture—The practice of planting and controlling the growth and 

composition of a forest. Silviculture is used for managing forests for timber 

production, wildlife, water, recreation, and aesthetics, among other uses or 

combination thereof. 

Soil complex—Soil mapping unit made of two or more types of soils. 

Species—A distinct group of living organisms that are capable of breeding 

among themselves.

Species richness—The number of different kinds of animals or plants that call a 

space home. 

Symbiosis—An interdependent relationship between two or more species.

Trade winds—Global wind currents that prevail in the tropics and subtropics 

worldwide, blowing from the northeast in the northern hemisphere and the 

southeast in the southern hemisphere. 

Trailhead—The place where a hiking trail begins.

Topography—The shape and features of the planet’s surface.

Wilderness—Land protected under The Wilderness Act of 1964 (Public Law 88–

577), which defines wilderness as “an area where the earth and its community 

of life are untrammeled by humans, where humans themselves are a visitor 

who does not remain; [and] an area of undeveloped U.S. federal land retaining 

its primeval character and influence, without permanent improvements or 

human habitation, which is protected and managed so as to preserve its 

natural conditions.” 57 

62
Abbreviations

oC — degrees in Celsius

oF — degrees in Fahrenheit

g/p/d — gallons per person per day

ha — hectares, a measurement of area. One hectare is equivalent to 2.47 acres.

km — kilometer

m — meter 

Mgal/day — million gallons per day

mm — millimeters 

pers. — persons

PR — Puerto Rico

UNESCO — United Nations Educational, Scientific, and Cultural Organization

U.S. — United States

USDA — United States Department of Agriculture

yr — year

63