Guam’s Forest Resources: Forest 

Inventory and Analysis, 2013

Michelle Lazaro, Olaf Kuegler, Sharon Stanton, Ashley Lehman, 

Joseph Mafnas, and Mikhail Yatskov

DEPAR TMENT OF AGRICULT URE

United States Department of Agriculture

Forest 

Service

Pacific Northwest 

Research Station

Resource Bulletin

PNW-RB-270

February

2020
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Authors

Michelle Lazaro is a natural resources specialist, Hawai’i Conservation Alliance 

and Foundation, 1601 East-West Road, Honolulu, HI 96848-1601. Olaf Kuegler 

is a statistician and Sharon Stanton is a biological scientist, U.S. Department 

of Agriculture, Forest Service, Pacific Northwest Research Station, 620 SW 

Main Street, Suite 502, Portland, OR 97205. Ashley Lehman is a biologist, U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station, 161 

E 1st Avenue, Door 8, Anchorage, AK 99501-1639. Joseph Mafnas is chief forester, 

Guam Department of Agriculture, Forestry and Soil Resources Division, 163 Dairy 

Road, Mangilao, Guam 96913. Mikhail Yatskov is a forester, U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station, 161 E 1st Avenue, 

Door 8, Anchorage, AK 99501-1639. 

Contributing Authors

Thomas Thompson is a geographic information specialist, U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station, 161 E 1st Avenue, 

Door 8, Anchorage, AK 99501-1639; and Brett Davis is a biological science information specialist, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, 620 SW Main Street, Suite 502, Portland, OR 97205.

Cover: Forest and savannah mosaic on volcanic soils, southern Guam. Photo by 

Seth Ayotte.
Abstract

Lazaro, Michelle; Kuegler, Olaf; Stanton, Sharon; Lehman, Ashley; Mafnas, 

Joseph; Yatskov, Mikhail. 2020. Guam’s forest resources: Forest Inventory and 

Analysis, 2013. Resour. Bull. PNW-RB-270. Portland, OR: U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station. 43 p.

This report highlights key findings from 2013 data collected by the U.S. Department of Agriculture, Forest Service, Forest Inventory and Analysis program across 

all forested land on Guam, updating findings from data collected in 2002 that 

were published in Resource Bulletin PNW-RB-243. We summarize and interpret 

basic resource information such as estimates of forest area, stem volume, biomass, 

number of trees, damages to trees, and tree size distribution, as well as overstory 

and understory vegetation cover and information on invasive plant species presence 

and cover. Detailed tables and graphical highlights are included to help inform 

resource managers and policymakers, as well as to educate the public regarding the 

status and trends of their local natural resources. The appendixes provide details on 

inventory methods and design and include summary tables of data, with statistical 

errors, for the wide variety of forest characteristics inventoried.

Keywords: Guam, biomass, carbon, damage, forest land, inventory, vegetation, 

invasive plants.

Highlights

• Tallest measured tree: Vitex parviflora, 66 ft in height

• Estimated total forest area: 69,900 ac (table 1, p. 5)

• Estimated total number of live trees (≥1 inch diameter at breast height):

73.1 million (table A2-1, p. 30)

• Total number of tree species recorded: 55 species (“Scientific and Common 

Names of Plants Found During Inventory”, p. 18)

• Estimated total net live tree volume: 52.0 million ft3 (table A2-5, p. 35)

• Estimated total live tree aboveground biomass: 2.267 million dry tons 

(table A2-6, p. 36)

• Estimated total live tree aboveground carbon: 1.134 million dry tons 

(table A2-6, p. 36)
Contents

1 Guide to Forest Inventory and Analysis

1 Overview of the Purpose of This Report

1 Description of the Forest Inventory and Analysis Program 

2 Common FIA Terminology 

3 Forest Resources on Guam

3 Forest Area

7 Forest Composition

10 Volume, Biomass, and Carbon

11 Understory Vegetation

12 Extent of Standing Dead Wood

12 Nontimber Forest Products

13 Forest Health

14 Forest Disturbances and Their Extent

15 Insects

16 Invasive Vegetation

18 Conclusions

18 Scientific and Common Names of Plants Found During Inventory

22 Acknowledgments

23 Metric Equivalents 

23 Literature Cited 

26 Appendix 1: Inventory Design and Methods

29 Appendix 2: Summary Data Tables

40 Glossary
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American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Guide to Forest Inventory and Analysis

Overview of the Purpose of This Report

This report presents a summary of Guam’s forest resources from the most recent 

data collected by the U.S. Department of Agriculture (USDA) Forest Service Forest 

Inventory and Analysis (FIA) program in 2013 across all ownerships and forest 

types. It updates previously published findings from data collected in 2002 (Donnegan et al. 2004). We summarize and interpret basic resource information, including forest area, ownership, land use change, biomass, biodiversity, standing dead 

wood, and forest health indicators. The Pacific Northwest Research Station Forest 

Inventory and Analysis (PNW-FIA) program implemented a sampling strategy on 

Guam that measures forest and nonforest vegetated plots, within a single year, on 

an intended 10-year cycle. PNW-FIA partners with Guam’s researchers and forest 

managers to use the inventory data to help answer local and national questions 

about the status and trends in tropical forests. These data update those published in 

the earlier report; however, not all the values presented here can be directly compared to previous reports or datasets to assess change in Guam’s forest resources 

over the past decade. Consistent sampling and field protocols standardized across 

different ownerships and forest management regimes allow for comparisons of 

change over time only for certain attributes. This report covers all forested and 

vegetated nonforest lands on Guam, with estimates representing averaged values 

computed from all inventory plots visited by field crews in 2013.

Description of the Forest Inventory and Analysis Program 

The FIA program was established in 1928 to conduct unbiased assessments of the 

nation’s forested lands for use in economic and forest management planning. The 

program was charged with collecting forest data on a series of permanent field 

plots, compiling and making these data publicly available, and providing research 

and interpretations from the data. Four FIA units are responsible for inventories 

of all forested lands in the United States, including the insular areas and territories of Puerto Rico, Guam, American Samoa, Commonwealth of the Northern 

Mariana Islands, U.S. Virgin Islands, and freely associated Pacific Island nations 

of the Federated States of Micronesia, Republic of the Marshall Islands, and 

Republic of Palau. Historically, each of the four regional FIA units responsible 

for forest inventories in the United States implemented inventory methods to 

best fit its respective regional forest conditions and client needs, resulting in 

inconsistent national reporting (USDA FS 2006). After passage of the 1998 Farm 

Bill, the FIA program implemented an annualized inventory that was designed to 

be nationally consistent as well as spatially and temporally unbiased with respect 
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RESOURCE BULLETIN PNW-RB-270

to forest types and land ownership groups (Bechtold and Patterson 2005). All 

FIA units use a common plot design, common set of measurement protocols, and 

standard database design for compilation and distribution of data. Under this 

unified approach, FIA is able to provide unbiased estimates of a wide variety of 

forest conditions over all forested lands in the United States in a consistent and 

timely manner. 

The national design was adapted for the Guam inventory to include additional 

branching and rooting forms and additional tree crown measurements, as well 

as special interest species ranging from invasive plants to pathogens to invasive 

insects and animals. With significant project support from the Government of 

Guam’s Forestry Division and the University of Guam, 48 plots were spaced 

uniformly at 1.9-mi intervals using a hexagonal grid, resulting in a threefold 

intensification of the spacing used in the mainland U.S. inventory plot grid. Forest 

inventory plots included four 24-ft fixed-radius subplots, where a variety of information was collected at the plot, subplot, and tree levels (USDA FS 2012). Primary 

variables collected include plot location, slope, aspect, elevation, subplot slope 

position and slope shape, tree species, diameters, heights, damages, branching and 

rooting forms, decay, and epiphytic loadings. Additional information about annual 

inventories is available in appendix 1 of this report and at http://fia.fs.fed.us/.

Common FIA Terminology 

What is a tree?—

The U.S. Forest Service defines a tree as a woody perennial plant, usually with 

a single well-defined stem carrying a crown, with a minimum height of 15 ft at 

maturity (USDA FS 2006).

What is a forest? —

Forests come in many shapes and sizes, varying from complex and species diverse 

to monoculture plantations. The FIA program defines forest land as an area currently or formerly (within 30 years) having at least 10 percent crown cover by trees 

of any size and not currently developed for nonforest use (USDA FS 2006). Forest 

land must be at least 1 ac in size with a minimum continuous width of 120 ft.
3

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Forest Resources on Guam

The island of Guam (fig. 1) is the largest and farthest south in the north-sweeping 

Marianas archipelago (fig. 2). The highest point on the island is Mount Lamlam at 

1,332 ft elevation. Guam is an unincorporated territory of the United States and has 

the highest human population of any island in Micronesia. The climate is tropical marine with little annual variation in temperature, but with a pronounced dry 

season from January to May (Manner 1993) (fig. 3).

Forest Area

About half of Guam is forested (53 percent) (fig. 4). The island’s total land area 

is about 132,230 ac, with 69,851 forested ac (table 1). A significant area of land is 

occupied by the U.S. military; on a portion of this area, a system of refuges and 

wildlife reserves has been designated. For example, Ritidian Point, about 22,500 ac 

in size at the northern tip of Guam, is administered by the U.S. Fish and Wildlife 

Service as a national wildlife refuge. The northern half of the island is generally a 

flat limestone plateau that can be strongly weathered into rugged karst topography. 

The limestone soils in the north are covered with forest in areas that are not cultivated or urbanized. The southern side of the island features a terrain composed of 

deeply weathered volcanic soils primarily covered by grassland, with some ravine 

forest in sheltered and leeward sites.

Figure 1—Merizo, Guam, near ferry terminal to Cocos Island. .

Ashley Lehman
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RESOURCE BULLETIN PNW-RB-270

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Figure 2—Guam is an unincorporated territory of the United States in the North Pacific Ocean, about 1,600 mi east of Manila, Philippines, and 3,500 mi north of Melbourne, Australia.
5

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

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

Average temperature (°F)

Average precipitation (inches)

Month

Precipitation

Maximum temperature

Minimum temperature

Figure 3—Average maximum and minimum temperatures, and total monthly precipitation for Guam. Note the pronounced seasonality in 

precipitation (Western Regional Climate Center, https://wrcc.dri.edu/cgi-bin/cliMAIN.pl?pi4226).

Table 1—Estimated land area by status, 2013 

Land status Total

Acres

Accessible forest land:

Unreserved forest land 49,190

Reserved forest land (Bird Island Wildlife Conservation 

Area and Guam National Wildlife Refuge)

20,661

All accessible forest land 69,851

Nonforest and other areas:

Nonforest urban 36,659

Nonforest vegetation 25,720

Barren lands —

Water —

All nonforest and other 62,379

Total area 132,230

QuickBird satellite imagery from Digital Globe, Inc. (Longmont, Colorado) was used to 

develop the vegetation mapping layers (Liu 2014). Note: the use of trade or firm names 

in this publication is for reader information and does not imply endorsement by the U.S. 

Department of Agriculture of any product or service.

— = none.
6

RESOURCE BULLETIN PNW-RB-270

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Figure 4—Forested plots measured in 2013 used to provide the data published in this report. Locations of 48 forested plots were measured, and locations are approximate (forest/nonforest geographic information system layer: Liu et al. 2014).
7

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Forest Composition

FIA crews identified 55 tree species on FIA plots in Guam (see “Scientific and 

Common Names of Plants Found During Inventory”). The most common tree species were Leucaena leucocephala, Guamia mariannae, and Hibiscus tiliaceus (table 

2). The estimated total number of trees during this 2013 inventory was about 74 million. FIA plots on Guam each contained from 1 to 11 different tree species (fig. 5). 

Forest stands tended to be dominated by smaller size trees that are less than 5 inches 

in diameter (fig. 6). The diameter distribution for trees follows a reverse-J pattern on 

Guam (fig. 7). Frequent typhoon disturbance and the abundance of numerous species of small-diameter, short-lived trees (such as Leucaena leucocephala) contribute 

to this pattern, which is persistent through time in many stands.

Table 2—Estimated number of trees on Guam, by species (continued)

Number of trees

Scientific name Common name Total

Sampling 

error

Thousands

Leucaena leucocephala tangan tangan 9,341 2,983

Guamia mariannae paipai 9,207 3,996

Hibiscus tiliaceus sea-hibiscus, pago 9,049 2,452

Triphasia trifolia lemondichina 8,526 6,470

Vitex parviflora smallflower chastetree 4,584 1,661

Aglaia mariannensis mapunyao 4,532 3,241

Morinda citrifolia lada, 3,396 1,268

Premna obtusifolia ahgao 2,571 1,055

Heterospathe elata palma brava 2,182 1,408

Neisosperma oppositifolia fagot 1,973 1,304

Averrhoa bilimbi bilimbi, pickle tree 1,935 1,422

Areca catechu Pugua, betel nut 1,722 1,193

Casuarina equisetifolia gagu, ironwood 1,671 1,113

Ochrosia mariannensis langiti 1,603 1,547

Cocos nucifera niyok, coconut palm 1,464 528

Maytenus thompsonii luluhut 1,247 1,203

Pandanus tectorius kafu 1,131 352

Cananga odorata ilang-ilang 961 955

Adenanthera pavonina kulalis 834 826

Eugenia reinwardtiana a’abang 712 687

Cycas circinalis fandang, federico 624 242

Annona muricata laguaná, kasoy, soursop 623 437

Bauhinia monandra orchid tree, mariposa 481 484
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RESOURCE BULLETIN PNW-RB-270

Table 2—Estimated number of trees on Guam, by species (continued)

Number of trees

Scientific name Common name Total

Sampling 

error

Thousands

Calophyllum inophyllum da’ok 471 301

Ficus tinctoria hoda, tagete 357 306

Mangifera indica mångga, mango 208 196

Annona reticulata annonas, custard apple 200 126

Macaranga thompsonii pengua 186 129

Eugenia thompsonii atoto 178 172

Mammea odorata chopak 176 178

Melanolepis multiglandulosa alom 164 165

Chrysophyllum cainito star apple 152 153

Tarenna sambucina sumac-lada 152 153

Ficus prolixa nunu 150 81

Spathodea campanulata African tulip tree 124 82

Pisonia grandis umumu 85 86

Tristiropsis obtusangula faia, faniok 75 63

Artocarpus altilis lemmai, breadfruit 73 51

Intsia bijuga ifit 65 41

Artocarpus mariannensis dugdug, seeded breadfruit 37 20

Barringtonia asiatica puting, fish kill 37 37

Leucaena insularum native tangan tangan 35 36

tree unknown other or unknown live tree 27 18

Pandanus dubius pahong 25 18

Eugenia palumbis agatelang 14 14

Glochidion marianum Glochidion marianum 14 14

Barringtonia racemosa langasat 12 12

Hernandia sonora nonak 12 12

Tabebuia pallida pink tabebuia 12 12
9

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

0

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1 2 3 4 5 6 7 8 9 10 11

Number of plots

Number of species

0

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45

Small diameter Medium diameter Large diameter

Area (thousand acres)

Stand size class

Figure 6—Forest area by stand-size class. Forests in the large-diameter stand-size 

class are defined as having a majority of trees ≥11.0 inches in diameter at breast 

height (d.b.h.). Forests in the medium-diameter stand-size class are defined as 

having a majority of trees between 5.0 and 11.0 inches d.b.h. Forests in the smalldiameter stand-size class have a majority of trees with d.b.h. <5.0 inches.

Figure 5—Number of tree species found on Forest Inventory and Analysis sampled plots. The average number of tree species per field-visited plot was 5 and ranged from 1 to 11 species per plot based 

on the 45 plots with inventoried trees.
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RESOURCE BULLETIN PNW-RB-270

Volume, Biomass, and Carbon

Stem volume (wood) is a metric by which forest productivity, vigor, and structure 

can be assessed and modeled to examine current forest conditions and project 

future forest status. Field-derived tree length and diameter measurements are used 

to produce single-tree volume estimates, which are then expanded to assess volume 

for entire forested stands. Volume estimates can then be used in additional models 

to study forest biomass and carbon dynamics. Biomass and carbon distribution by 

diameter class follows closely the pattern seen in volume by diameter-class distribution (tables A2-5 and A2-6), in which biomass was concentrated in the small 

to medium stand-size classes. Trees 5.0 to 9.9 inches in diameter represented the 

highest overall pool of aboveground biomass (fig. 8). 

0

10

20

30

40

50

60

Number of live trees (millions)

Diameter (inches)

0–2.9 3.0–4.9 5.0–6.9 7.0–8.9 9.0–10.9 11.0–14.9 15+

Figure 7—Estimated number of live trees by diameter class in 2013. Smaller trees are the most 

numerous across all size classes, indicating that regeneration is abundant.
11

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Understory Vegetation

Understory vegetation is an important structural component in all forest ecosystems. The life form type and density of cover could affect forest structure and 

function, as well as influence wildlife habitat, spread of disease, soil stability, 

and competition between native and nonnative plants. FIA field crews sample 

understory vegetation in plots on forest and vegetated nonforest land. To reflect 

forest structure, the percentage of canopy cover by four structural layers and the 

percentage of total canopy cover to 1 percent are estimated for tree seedlings (trees 

<1.0 inch in diameter at breast height [d.b.h.]) and saplings (trees 1.0 to 4.9 inches 

d.b.h.); shrubs (woody, multiple-stem plants of any size, including woody vines); 

forbs (herbaceous, broadleaf plants, including nonwoody vines and ferns); and 

graminoids (grasses and grass-like plants, including rushes and sedges). To reflect 

species composition, the percentages of total canopy cover and main canopy layer 

are estimated for the four most abundant (≥3 percent canopy cover) life forms: 

seedlings and saplings, shrubs, forbs, and graminoid species. Graminoids were the 

most common understory vegetation found on all FIA plots, followed by seedlings 

and saplings, shrubs, and woody vines (fig. 9).

100

0

200

300

400

500

600

700

800

900

1,000

0–4.9 5.0–9.9 10.0–14.9 15.0+

Stem biomass (thousand tons)

Diameter class (inches)

Figure 8—Stem biomass (thousand tons) by diameter class. On Guam, stem biomass is 

generally present in the small to medium stand-size classes.
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RESOURCE BULLETIN PNW-RB-270

Extent of Standing Dead Wood

Standing dead trees (snags) represent an important component of forest structure 

and wildlife habitat. FIA plot measurements are well suited to estimating standing 

dead wood throughout all forest types and ownerships across the island. Dead trees 

fill many ecologically important roles in forests. Dead wood in a forest provides 

habitat for wildlife, insects, and fungi (both native and invasive); improves soil 

fertility through nutrient cycling and moisture retention; adds to fuel loads; and 

is a key structural element in mature forests. Large-scale disturbances caused by 

weather events and insects can substantially increase input into the dead wood 

pool, leading to a notable effect on the total dead wood stores present. Dead wood 

resources are complex, and FIA provides estimates of the amount of standing dead 

trees (snags). There are approximately 30,251 tons of dead wood on Guam: 21,331 

tons in the 5.0- to 9.9-inch diameter class and 8,920 tons in the >10-inch diameter 

class (fig. 10; table A2-6).

Nontimber Forest Products

Nontimber forest products are those not traditionally included as timber in economic reporting. These products contribute in important ways to the livelihoods 

and welfare of people living in and near forests. They provide construction materials, fencing, furniture, foods, medicines, fibers, floral products, plant oils, dyes, 

food wrapping, fuels, and livestock feed, and represent other important cultural 

values (Dawson et al. 2014). In Guam’s FIA plots, Cocos nucifera and Pandanus 

tectorius had the highest number of trees of these species of interest (fig. 11) and are 

used as a food crop and for handicrafts.

0 5 10 15 20 25

Forbs

Graminoids

Seedlings

and saplings

Shrubs and

woody vines

Average cover (percent)

Understory vegetation life form

Figure 9—Average understory vegetation canopy cover percentage by life form in Guam’s forests.
13

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Forest Health

Forests are complex ecosystems composed of plants, animals, fungi, and bacteria that 

interact with each other and with nonbiotic elements. Trees dominate forested landscapes, but less obvious components such as fungi and soil microbes are also important 

(Molina 1994), with each piece of the system playing a role in creating a balanced and 

healthy environment. Forests can sequester carbon from the atmosphere, serve as longterm carbon storage (Harmon et al. 1990), protect soil from erosion, and remove pollutants to improve air quality (Nowak et al. 2014). On Guam, forests comprise nearly 53 

percent of the land area, and the health of these forests affects their ability to maintain 

forest species composition and function and protect surrounding environments. 

0

5

10

15

20

25

30

5.0–9.9 10+

Dead tree biomass (thousands of tons)

Diameter class (inches)

500 1,000 1,500 2,000 2,500

Cocos nucifera

Pandanus tectorius

Annona muricata

Mangifera indica

Chrysophyllum cainito

Artocarpus altilis

Artocarpus mariannensis

Number of trees (thousands)

Scientific name of selected 

nontimber forest products 

Figure 10—Aboveground standing 

dead tree biomass for trees with a 

diameter greater than 5 inches.

Figure 11—Number of trees in the thousands of selected nontimber forest product species. Cocos nucifera and

Pandanus tectorius had the highest number of trees of the nontimber forest products sampled.
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RESOURCE BULLETIN PNW-RB-270

Forest Disturbances and Their Extent

The forests on Guam have been affected by typhoons, droughts, urbanization, wildfires, and invasions of introduced insects, plants, and ungulate species. Introduced 

ungulates such as the Philippine deer (Rusa marianna) and feral pigs (Sus scrofa)

consume seeds, fruits, and foliage, and trample and uproot regenerating plants, 

inhibiting forest regeneration (Morton et al. 2000). In the mid-1940s, the unintentional introduction of the brown tree snake (Boiga irregularis) led to the functional 

extirpation of native seed dispersing birds from the forests (Rogers et al. 2017). 

Declines and losses of native species as a result of these disturbances have been 

especially severe on Guam, prompting the U.S. Fish and Wildlife Service, in 2015, to 

add 23 species to the federal list of endangered and threatened wildlife and plants on 

Guam (50 C.F.R. § 17 2015). Guam is located in “Typhoon Alley,” where interactions 

between frequent tropical storms and anthropogenic disturbances, which expose soil 

and fragment ecosystems, have greatly altered natural communities (Mafnas 2010). 

Guam is also anticipating an increase in its human population because of the expansion of U.S. military installations, where proposed housing development and other 

activities are expected to eliminate about 9 percent of Guam’s forest area (Mafnas 

2010). Disturbances on forest and nonforest land on Guam were generally caused by 

fire, animals and insects (fig. 12). The presence of conks, other fungi fruiting bodies, 

and signs of advanced decay, i.e., rot in sapwood/heartwood of trees, represented the 

majority of tree damage (57 percent) observed in inventory plots (fig. 13). 

30%

20%

16%

None found

Fire damage

Animal damage (deer/pig)

Insect damage

34%

Figure 12—Area affected by type of disturbance on Guam. 
15

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Insects

In 2003, an unintentional introduction of cycad scale (Aulacaspis yasumatsui) on 

Guam resulted in a steep decline in the population of native cycad species (Cycas 

circinalis), raising many concerns about the subsequent ecosystem response 

(Marler and Lawrence 2012). Rhinoceros beetle (Oryctes rhinoceros)

was found on Guam in 2007 and 

has the potential to cause significant 

damage to Guam’s forest ecosystems 

and economy (Mankin and Moore 

2010). During the 2013 inventory, 93 

percent of Cycas circinalis showed 

signs of damage as a result of cycad 

scale, and 15 percent of Cocos 

nucifera showed signs of damage 

from the rhinoceros beetle (fig. 14). 

Conks, fruiting bodies, and signs 

 of advanced decay

Loss of apical dominance, 

 dead terminal

Open wounds

Vines in the crown

Broken or dead

Damaged buds, foliage, or shoots

Other

57%

12%

10%

9%

7%

4%

1%

Figure 13—Tree damage types occurring on live trees in Forest Inventory and Analysis plots. The 

majority of damages to saplings and trees were conks, fruiting bodies, and signs of advanced decay.

0

200

400

600

800

1,000

1,200

1,400

Cocos nucifera Cycas circinalis

Number of live trees measured

Scientific name

No damage present

Damages present from cycad scale 

 or rhinoceros beetle

Figure 14—Severity of damage from Cycad scale in Cycas circinalis and rhinoceros 

beetle in Cocos nucifera.
16

RESOURCE BULLETIN PNW-RB-270

Invasive Vegetation

Invasive plants can significantly alter forest structure and composition and can 

diminish ecosystem resilience to other disturbance processes. Accidental or intentional introductions of forbs, shrubs, vines, and trees have profoundly affected 

the environment on Guam (fig. 15). Invasive plants tend to proliferate owing to 

an absence of natural enemies and the inability of native plant species to compete 

with invasive species (Muniappan et al. 2002). During World War II, large areas 

of vegetation were cleared, leading to an increase in nonnative woody species such 

as Leucaena leucocephala (Fosberg 1960, Savidge 1987). Small oceanic islands 

are exceptionally vulnerable to damages caused by intentional and unintentional 

introduction of alien species that, once established, are difficult or even impossible to eradicate (Marler and Lawrence 2012, Van Driesche et al. 2010). Nineteen 

invasive species out of a list of 38 species identified by local land managers were 

found during the 2013 inventory (table 3). Vitex parviflora and Leucaena leucocephala were the most dominant invasive plant species present in 2013 (fig. 16).

Figure 15—Invasive species, 

such as Mikania micrantha 

shown here, can outcompete and 

take over a landscape on Guam.

Ashley Lehman
17

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Table 3—Presence or absence of listed Guam invasive species

Scientific name Presence/absence Scientific name Presence/absence

Achyranthes aspera — Imperata cylindrica —

Adenanthera pavonina  Lantana camara —

Amaranthus spinosus — Leucaena leucocephala 

Antigonon leptopus  Lemna minor —

Arundina graminifolia  Lonicera japonica —

Averrhoa bilimbi  Mimosa diplotricha (M. invisia) —

Bidens alba  Mikania micrantha 

Chromolaena odorata  Mucuna pruriens 

Cinnamomum verum — Nymphaea sp. —

Clerodendrum chinense — Pennisetum polystachion 

Clerodendrum sp. — Piper auritum —

Coccinia grandis — Pistia stratiotes —

Egeria densa — Spathodea campanulata 

Eichhornia crassipes — Stachytarpheta jamaicensis 

Epipremnum pinnatum  Syngonium podophyllum 

Euphorbia cyathophora  Tinospora sp. —

Falcataria moluccana — Tradescantia spathacea 

Heterospathe elata  Panicum maximum (Urochloa maxima) 

Hydrilla verticillata — Vitex parviflora 

Note: 38 species were searched for; 19 species were found on plots.

 = species was found during Forest Inventory and Analysis (FIA) inventory.

— = species was not found during FIA inventory.

0 2 4 6 8 10 12 14 16 18

Vitex parviflora

Leucaena leucocephala

Heterospathe elata

Antigonon leptopus

Mikania micrantha

Averrhoa bilimbi

Epipremnum pinnatum

Cover on forest land (percent)

Scientific name

Figure 16—Total percentage of cover of invasive species present in the vegetation in Guam’s forested lands. Vitex parviflora and 

Leucaena leucocephala were the most dominant invasive vegetation species present during the 2013 inventory.
18

RESOURCE BULLETIN PNW-RB-270

Scientific and Common Names of Plants Found During Inventory

Life form Scientific name Common name

Trees: Adenanthera pavonina L. kulalis

Aglaia mariannensis sensu Kaneh., non Merr. mapunyao

Annona muricata L. laguaná, kasoy, soursop

Annona reticulata L. annonas, custard apple

Areca catechu L. puguá, betel nut

Artocarpus altilis (Parkinson) Fosberg lemmai, breadfruit

Artocarpus mariannensis Trécul dugdug, seeded breadfruit

Averrhoa bilimbi L. bilimbi, pickle tree

Barringtonia asiatica (L.) Kurz puting, fish kill, sea putat

Barringtonia racemosa Roxb. langaasag

Bauhinia monandra Kurz orchid tree, mariposa

Calophyllum inophyllum L. da’ok

Cananga odorata (Lam.) Hook. f. & Thomson ilang-ilang

Carica papaya L. papaya

Casuarina equisetifolia L. gagu, ironwood

Cerbera dilatata Markgr. chiute

Chrysophyllum cainito L. star apple

Cocos nucifera L. niyok, coconut palm

Cyathea lunulata (G. Forst.) Copel. tsatsa, Pacific tree fern

Cycas circinalis L. fandang, federico

Eugenia palumbis Merr. agatelang

Eugenia reinwardtiana (Blume) DC. a’abang

Eugenia thompsonii (Merr.) N.Snow atoto

Conclusions

This report presents an updated overview of Guam’s forest resources, highlighting information that is new as well as confirming previously known information. 

Some readers may want to see more indepth research and analysis on selected 

topics to fully understand the current state and changes taking place in Guam’s 

forests. Note, however, that not all the results published in this report can be 

directly compared to those in the previous report (Donnegan et al. 2004) for the 

purpose of assessing changes in forest resources over the past decade. Use of the 

same sampling protocols and plot design in the future will support meaningful 

assessment of change in each 10-year interval between field visits. Long-term 

forest monitoring in FIA plots is expected to provide information on the impacts 

of disturbances such as invasive species on tree growth and survival. Armed with 

these data, we can begin quantifying trends in Guam’s forest, from the growth and 

survival of understory seedlings to large, landscape-level shifts in forests from 

such challenges associated with a growing population and a changing climate. 
19

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Life form Scientific name Common name

Ficus prolixa G. Forst. Nunu, fig

Ficus tinctoria G. Forst. hoda, tagete, fig

Glochidion marianum Müll. Arg. Glochidion marianum

Guamia mariannae (Saff.) Merr. paipai

Hernandia ovigera L. oschal

Hernandia sonora L. nonak, mago

Heterospathe elata Scheff. palma brava

Hibiscus tiliaceus L. sea hibiscus, pago

Inocarpus fagifer (Parkinson) F.R. Fosberg budo buoy, Tahitian chestnut

Intsia bijuga (Colebr.) Kuntze ifit

Kleinhovia hospita L. guest tree

Leucaena insularum (Guill.) Daniker native tangan tangan

Leucaena leucocephala (Lam.) de Wit tangan tangan

Macaranga thompsonii Merr. pengua

Mammea odorata (Raf.) Kosterm. chopak

Mangifera indica L. mångga, mango

Maytenus thompsonii (Merr.) Fosberg luluhut

Melanolepis multiglandulosa (Reinw. ex Blume) Rchb. f. & Zoll. alom

Morinda citrifolia L. lada

Neisosperma oppositifolia (Lam.) Fosberg & Sachet fagot

Ochrosia mariannensis A. DC. langiti

Pandanus dubius Spreng. pahong

Pandanus tectorius Parkinson ex Zucc. kafu, kaffo, Tahitian screwpine

Pisonia grandis R. Br. amumo

Polyscias grandifolia Volkens pepega

Premna obtusifolia R. Br. ahgao, premna

Spathodea campanulata P. Beauv. African tulip tree

Tabebuia pallida (Lindl.) Miers pink tabebuia

Tarenna sambucina (G. Forst.) Durand sumac-lada

Triphasia trifolia (Burm. f.) P. Wilson lemondichina

Tristiropsis obtusangula Radlk. faia, faniok

Vitex parviflora Juss. smallflower chastetree

Forbs: Abelmoschus moschatus Medik. musk okra

Alocasia cucullata (Lour.) G. Don Chinese taro

Alocasia macrorrhizos (L.) G. Don giant taro

Antigonon leptopus Hook. & Arn. coral vine, chain of love

Arundina graminifolia (D. Don) Hochr. bamboo orchid

Asplenium nidus L. Hawaii birdnest fern

Bidens alba (L.) DC. romerillo

Chromolaena odorata (L.) R.M. King & H. Rob. Siam weed, kesengesil, masigsig

Curcuma longa L. common turmeric

Scientific and Common Names of Plants Found During Inventory (continued)
20

RESOURCE BULLETIN PNW-RB-270

Life form Scientific name Common name

Dicranopteris linearis (Burm.) Underw. Old World forkedfern

Epipremnum pinnatum (L.) Engl. pothos, centipede tongavine

Gleichenia linearis (Burm. f.) C.B. Clarke

Hyptis capitata Jacq. false ironwort

Hyptis rhomboidea Martius & Galeott

Ipomoea pes-caprae (L.) R. Br. bayhops

Ipomoea pes-caprae (L.) R. Br. ssp. brasiliensis (L.) van Ooststr. Brazilian bayhops

Lycopodiella cernua (L.) Pic. Serm. var. cernua staghorn clubmoss

Lygodium microphyllum (Cav.) R. Br. small-leaf climbing fern

Lygodium scandens

Malvastrum coromandelianum (L.) Garcke threelobe false mallow

Microlepia speluncae (L.) T. Moore limpleaf fern

Mikania micrantha Kunth bittervine, mile-a-minute vine

Mimosa pudica L. shameplant, sleeping grass

Mucuna pruriens (L.) DC. cowitch, velvet bean, akangkang dangkulo

Musa L. banana

Nephrolepis biserrata (Sw.) Schott giant swordfern

Nephrolepis hirsutula (J.R. Forst.) C. Presl scaly swordfern

Passiflora foetida L. fetid passionflower

Passiflora suberosa L. corkystem passionflower, devils pumpkin

Phymatosorus scolopendria (Burm. f.) Pic. Serm. monarch fern

Polypodium punctatum Thunb. ex Murray elkhorn fern

Pteris tripartita Sw. giant brake

Pyrrosia lanceolata (L.) Farw. Lanceleaf tongue fern

Senna tora (L.) Roxb. sickle senna

Sida rhombifolia L. Cuban jute

Spathoglottis plicata Blume Philippine ground orchid

Sphagneticola trilobata (L.) Pruski Bay Biscayne creeping-oxeye

Stachytarpheta jamaicensis (L.) Vahl light-blue snakeweed

Stictocardia tiliifolia (Desr.) Hallier f. spottedheart

Stylosanthes guianensis (Aubl.) Sw.

Syngonium podophyllum Schott American evergreen

Teramnus labialis (L. f.) Spreng. blue wiss

Thelypteris maemonensis (W.H. Wagner & Grether) B.C. Stone Maemon Valley maiden fern

Thelypteris opulenta (Kaulf.) Fosberg jeweled maiden fern

Thelypteris parasitica (L.) Fosberg parasitic maiden fern

Thelypteris pennata (Poir.) Morton graceful maiden fern

Thelypteris unita (L.) Morton

Tradescantia spathacea Sw. boatlily, moses-in-the-cradle

Vigna adenantha (G. Mey.) Marechal, Mascherpa & Stanier wild pea

Waltheria indica L. uhaloa

Wedelia Jacq. creepingoxeye

Scientific and Common Names of Plants Found During Inventory (continued)
21

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Life form Scientific name Common name

Graminoids: Bothriochloa bladhii (Retz.) S.T. Blake Caucasian bluestem

Centotheca latifolia (L.) Desv.

Cynodon dactylon (L.) Pers. bermudagrass

Dimeria chloridiformis sensu Ohwi 1941, non (Gaudich.) 

K. Schum. & Lauterb.

Eleusine indica (L.) Gaertn. Indian goosegrass

Fimbristylis dichotoma (L.) Vahl forked fimbry

Fimbristylis tristachya R. Br. fimbry

Imperata conferta (J. Presl) Ohwi

Miscanthus floridulus (Labill.) Warb. ex K. Schum. & Lauterb. swordgrass

Oplismenus compositus (L.) P. Beauv running mountaingrass

Oplismenus hirtellus (L.) P. Beauv basketgrass

Paspalum paniculatum L. arrocillo

Pennisetum polystachion (L.) Schult. mission grass

Pennisetum polystachion (L.) Schult. ssp. Setosum (Sw.) Brunken mission grass

Phragmites karka (Retz.) Trin. ex Steud. [excluded] tall reed

Rhynchospora rubra Domin rhynchospora

Saccharum spontaneum L. wild sugarcane

Scleria polycarpa Boeckeler nutrush

Sorghum halepense (L.) Pers. Johnsongrass

Urochloa maxima (Jacq.) R. Webster guineagrass

Shrubs and 

woody 

vines:

Abrus precatorius L. rosarypea

Cestrum diurnum L. day jessamine

Colubrina asiatica (L.) Brongn. Asian nakedwood

Discocalyx megacarpa Merr.

Entada pursaetha DC.

Flagellaria indica L.

Flemingia strobilifera (L.) W.T. Aiton wildhops

Freycinetia reineckei Warb. iul (Palau)

Ixora triantha Volkens

Jasminum marianum DC.

Medinilla medinilliana (Gaudich.) Fosberg & Sachet

Melastoma malabathricum L. Malabar melastome

Melastoma malabathricum var. mariannum

Miconia punctata (Desr.) D. Don ex DC. auquey

Myrtella bennigseniana (Volkens) Diels

Scaevola sericea Vahl beach naupaka

Scaevola sericea Vahl var. taccada (Gaertn.) Thieret & B. 

Lipscomb

nanaso, beach naupaka

Telosma Coville telosma

Wikstroemia elliptica Merr. gapit atayaki

Scientific and Common Names of Plants Found During Inventory (continued)
22

RESOURCE BULLETIN PNW-RB-270

Acknowledgments

This project would not have been possible without the close collaboration of the 

Government of Guam’s Department of Agriculture Forestry Division; the University of Guam (UOG); and the U.S. Forest Service. Guam’s Department of Agriculture provided logistical support, and the UOG hired and managed field personnel.

We thank the Guam Forestry Division for supporting field crew access to plot 

locations as well as providing vehicles, staff support, and office space, with particular thanks to Justin Santos, Joe Mafnas, Bel Soliva, and Ruddy Estoy, who helped 

set up plot access, managed staff and crew schedules, and conducted outreach to 

private landowners and local communities. Forestry Division field crew members 

Carlos Medina, Johnny San Nicolas, Kulian Salil, Kenneth Aguon, Patrick Quenga, 

and Greg Dirige helped us collect quality data and reach a timely completion of 

field work. Thanks also go to the Guam Department of Land Management and 

Bureau of Statistics and Planning for additional support. 

We acknowledge the role of UOG professor James McConnell, who helped 

develop a partnership of the UOG, Micronesia Challenge Terrestrial monitoring program, Forest Service, and Guam Forestry Division. He remains an active 

player in current programs and an idea generator for future collaborations. We 

also thank Else Demuelenaere for helping to coordinate the UOG staff, participating in FIA plot remeasurement and installation, field data cleanup, and managing 

the project to collect additional monitoring data as part of the Micronesia Challenge program. We are grateful to Else Demuelenaere, John Benedict, Jonathan 

“Kawika” Davis, Ron Manzano, Anthony Santos, Robert Alexander, Jivan Ramachandran, and Jesse Hines for their dedication to collecting high-quality data. 

We also thank several prominent regional scientists for their input to FIA protocol 

and for providing training to FIA crews in data collection on insect and pathogen 

damages. Thanks are due to Aubrey Moore, Roland Quitugua, and Robert Schlub, 

University of Guam, and to Phil Cannon, Sheri Smith, David Bakke, and Kathleen 

Friday, U.S. Forest Service Pacific Southwest Region State and Private Forestry. 

We also thank Lauren Gutierrez for her efforts in training FIA field staff in plant 

identification on Guam. 

We thank our crew leaders, including Seth Ayotte, and Matthew O’Driscoll, for 

their significant input to field protocol revisions, training of new project staff, and 

attention to detail and data quality throughout the field season. Finally, we thank 

the members of the information management team for compiling the Guam raw plot 

measurements into meaningful data for analysis, and the reviewers of this manuscript for their invaluable comments. 
23

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Metric Equivalents 

When you know: Multiply by: To find: 

Inches 2.54 Centimeters 

Feet (ft) 0.3048 Meters 

Acres (ac) 0.405 Hectares 

Cubic feet (ft3

) 0.0283 Cubic meters 

Tons (ton) 0.907 Tonnes or megagrams

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Appendix 1: Inventory Design and Methods

Field Design and Sampling Method

The Forest Inventory and Analysis (FIA) program conducts a systematic, samplebased field inventory across all ownerships on a periodic basis, remeasuring the 

same plots approximately every 10 years. All FIA units use a common plot design, 

common set of measurement protocols, and a standard database design for compilation and distribution of data. Adaptations were made to the national design for the 

Guam inventory to include additional branching and rooting forms and additional 

tree crown measurements, as well as special interest species ranging from invasive 

plants to pathogens to invasive insects and animals.

With active assistance from our partners at the University of Guam, 48 plots 

were spaced uniformly at 1.9-mi intervals using a hexagonal grid, at a threefold 

intensification of the spacing used in the mainland United States inventory plot 

grid. Forest inventory plots included four 24-ft, fixed-radius subplots in which a 

variety of information is collected at the plot, subplot, and tree levels (USDA FS 

2012). Primary variables collected include plot location, slope, aspect, elevation, 

subplot slope position and slope shape, tree species, diameters, heights, damages, 

branching and rooting forms, decay, and epiphytic loadings.

All plots classified by aerial photography as possibly being forested are established in the field without regard to land use or land cover. Field crews delineate 

areas within the plot that are comparatively less heterogeneous than the plot as a 

whole with regard to reserved status, owner group, forest type, stand-size class, and 

tree density; these areas are described as condition classes. The process of delineating these condition classes on a fixed-radius subplot is called mapping. All measured trees are assigned to the mapped condition class in which they are located.

On plots, crews assess physical characteristics such as slope, aspect, and 

elevation; stand characteristics such as age, size class, forest type, disturbance, site 

productivity, and regeneration status; and tree characteristics such as tree species, 

diameter, height, damages, decay, and vertical crown dimensions. They also collect 

general descriptive information such as proximity to water and roads and the 

geographic position of the plot in the larger landscape.

Estimates of tree volume and other forest attributes were derived from tree 

measurements and classifications made at each plot. A number of other variables 

are unique to the Pacific Northwest Research Station’s FIA program. These are 

“regional” variables and include such items as insect and disease damage, a record 

of previous disturbance on the plot. The Pacific Islands standardized plot installed 

at each forested location is a cluster of four subplots spaced 120 ft apart (fig. A1-1). 

Subplot 1 is in the center, with subplots 2 through 4 distributed radically around it. 
27

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Each point serves as the center of a 1/24-ac circular subplot used to sample all trees 

at least 5.0 inches in diameter at breast height (d.b.h.). A 1/300-ac microplot, with 

its center located 12 ft east of each subplot center, is used to sample trees 1.0 to 4.9 

inches d.b.h., as well as seedlings (trees less than 1.0 inch d.b.h.). 

Data Processing 

The data used for this report are stored in the FIA National Information Management System (NIMS), which provides a means to input, edit, process, manage, 

and distribute FIA data. It includes a process for data loading, a national set of edit 

checks to ensure data consistency, an error correction process, approved equations 

and algorithms, code to compile and calculate attributes, a table report generator, 

and routines to populate the presentation database. The NIMS applies numerous 

algorithms and equations to calculate such variables as stand size, volume, and 

Distance between subplot centers: 120 feet

Distance from subplot center to microplot center: 12 feet

N

6.8-foot radius microplot: seedlings + saplings

24-foot radius subplot: all trees (≥5 inches)

1

2

4 3

Subplot Microplot

Figure A1-1—The Forest Inventory and Analysis plot design used on Guam.
28

RESOURCE BULLETIN PNW-RB-270

biomass. It also generates estimates and associated statistics based on county areas 

and stratum weights developed outside of NIMS. Additional FIA statistical design 

and estimation techniques are further reviewed in Bechtold and Patterson (2005).

Statistical Estimates

Throughout this report, we have published standard errors (SE) for most of our 

estimates. These SEs account for the fact that we measured only a small sample 

of the forest (thereby producing a sample-based estimate) and not the entire forest 

(which is the population parameter of interest). Because of small sample sizes or 

high variability within the population, some estimates can be very imprecise. The 

reader is encouraged to take the SE into account when drawing any inference. One 

way to consider this type of uncertainty is to construct confidence intervals. Customarily, 66- or 95-percent confidence intervals are used. A 95-percent confidence 

interval means that one can be 95 percent confident that the interval contains the 

true population parameter of interest. For more details about confidence intervals, 

please consult Moore and McCabe (1989) or other statistical literature.

Access Denied, Hazardous, or Inaccessible Plots 

Although every effort was made to visit all field plots that were entirely or partially 

forested, some were not sampled for a variety of reasons. Field crews may have 

been unable to obtain permission from the landowner to access the plot, and some 

plots were impossible for crews to safely reach or access. Some private landowners 

deny access to their land, but privately owned plots usually are not as hazardous 

or inaccessible as plots on public land. Although permission to visit public land is 

almost always granted, some public land lies in higher elevation areas that can be 

very dangerous or impossible to reach.

This kind of missing data can introduce bias into the estimates if the nonsampled plots tend to be different from the entire population. Plots that are obviously nonforested (based on aerial photos) are rarely visited, and therefore the 

proportion of denied-access, hazardous, or inaccessible plots is significantly smaller 

than it is for forested plots. The poststratification approach outlined in Bechtold 

and Patterson (2005) removes nonsampled plots from the sample. Estimates are 

adjusted for plots that are partially nonsampled by increasing the estimates by the 

nonsampled proportion within each stratum. 
29

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Appendix 2: Summary Data Tables

The following tables contain basic information about the forest resources of Guam 

as they relate to the discussion of current forest issues and basic forest resource 

information presented in this report. Data are also available for download in 

nonsummarized form at https://www.fia.fs.fed.us.

Number of Live Trees

Table A2-1—Number of live trees on forest land by diameter class

Table A2-2—Percentage of live trees on forest land by species

Table A2-3—Number of live trees on forest land by species and diameter class

Tree Volume

Table A2-4—Estimated net volume of live trees on forest land by species and 

diameter class

Table A2-5—Estimated volume of all live trees on forest land by diameter class

Biomass and Carbon

Table A2-6—Aboveground biomass and carbon of live and dead trees on forest land

Table A2-7—Aboveground biomass of live trees on forest land by species and 

diameter class

Understory Vegetation

Table A2-8—Average understory vegetation cover and number of Forest Inventory 

and Analysis plots where the species occurred
30

RESOURCE BULLETIN PNW-RB-270

Table A2-1—Number of live treesa on forest land by diameter class

Estimated number of live trees

Diameter class Total SE

Inches Millions

0–2.9 45.3 9.4

3.0–4.9 16.8 2.8

5.0–6.9 6.1 1.1

7.0–8.9 2.0 0.3

9.0–10.9 1.5 0.3

11.0–14.9 1.0 0.2

15+ 0.4 0.1

Note: Totals may be off because of rounding; estimates are subject to sampling error.

SE = sampling error.

a

 Includes all live trees ≥1 inches in diameter at breast height.

Table A2-2—Percentage of live treesa on forest land by species (continued)

Scientific name Common name

Percentage of 

all trees

Leucaena leucocephala Tangan tangan 12.72

Guamia mariannae paipai 12.54

Hibiscus tiliaceus sea-hibiscus, pago 12.33

Triphasia trifolia lemondichina 11.61

Vitex parviflora smallflower chastetree 6.24

Aglaia mariannensis mapunyao 6.17

Morinda citrifolia lada 4.63

Premna obtusifolia ahgao 3.50

Heterospathe elata palma brava 2.97

Neisosperma oppositifolia fagot 2.69

Averrhoa bilimbi bilimbi, pickle tree 2.64

Areca catechu Puguá, betel nut 2.35

Casuarina equisetifolia gagu, ironwood 2.28

Ochrosia mariannensis langiti 2.18

Cocos nucifera niyok, coconut palm 1.99

Maytenus thompsonii luluhut 1.70

Pandanus tectorius Kafu, kaffo 1.54

Cananga odorata ilang-ilang 1.31

Adenanthera pavonina kulalis 1.14

Eugenia reinwardtiana a’abang 0.97

Cycas circinalis fandang, federico 0.85

Annona muricata laguaná, kasoy, soursop 0.85

Bauhinia monandra orchid tree, mariposa 0.66
31

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Table A2-2—Percentage of live treesa on forest land by species (continued)

Scientific name Common name

Percentage of 

all trees

Calophyllum inophyllum daok 0.64

Ficus tinctoria hoda, tagete 0.49

Mangifera indica mango 0.28

Annona reticulata annonas, custard apple 0.27

Macaranga thompsonii pengua 0.25

Eugenia thompsonii atoto 0.24

Mammea odorata chopak 0.24

Melanolepis multiglandulosa alom 0.22

Chrysophyllum cainito star apple 0.21

Tarenna sambucina sumac-lada 0.21

Ficus prolixa nunu 0.20

Spathodea campanulata African tulip tree 0.17

Pisonia grandis amumo 0.12

Tristiropsis obtusangula fai’a 0.10

Artocarpus altilis lemmai, breadfruit 0.10

Intsia bijuga ifit 0.09

Artocarpus mariannensis dugdug, seeded breadfruit 0.05

Barringtonia asiatica putting, fish kill 0.05

Leucaena insularum strand tangan tangan 0.05

tree unknown other or unknown live tree 0.04

Pandanus dubius pahong 0.03

Eugenia palumbis agatelang 0.02

Glochidion marianum Glochidion marianum 0.02

Barringtonia racemosa langaasag 0.02

Hernandia sonora nonak 0.02

Tabebuia pallida pink tabebuia 0.02

a Includes all live trees ≥1 inches diameter at breast height.
32

RESOURCE BULLETIN PNW-RB-270

Table A2-3—Number of live treesa on forest land by species and diameter class (continued)

Diameter class (inches)

0–4.9 5.0–9.9 10.0–14.9 15.0+ All classes

Scientific name Total SE Total SE Total SE Total SE Total SE

Number of trees (thousands)

Leucaena leucocephala 8,607 2,866 734 320 — — — — 9,341 2,983

Guamia mariannae 9,126 3,955 82 45 — — — — 9,207 3,996

Hibiscus tiliaceus 7,765 2,278 1,255 424 29 28 — — 9,049 2,452

Triphasia trifolia 8,526 6,470 — — — — — — 8,526 6,470

Vitex parviflora 2,855 1,433 1,206 340 421 164 102 42 4,584 1,661

Aglaia mariannensis 4,274 3,199 257 93 — — — — 4,532 3,241

Morinda citrifolia 3,322 1,246 75 42 — — — — 3,396 1,268

Premna obtusifolia 1,938 949 578 205 41 30 14 14 2,571 1,055

Heterospathe elata 1,060 687 1,122 868 — — — — 2,182 1,408

Neisosperma oppositifolia 1,673 1,247 286 214 14 14 — — 1,973 1,304

Averrhoa bilimbi 1,825 1,341 110 81 — — — — 1,935 1,422

Areca catechu 1,561 1,190 161 82 — — — — 1,722 1,193

Casuarina equisetifolia 1,472 1,066 155 92 43 41 — — 1,671 1,113

Ochrosia mariannensis 1,603 1,547 — — — — — — 1,603 1,547

Cocos nucifera — — 705 281 745 290 14 14 1,464 528

Maytenus thompsonii 1,247 1,203 — — — — — — 1,247 1,203

Pandanus tectorius 330 230 801 229 — — — — 1,131 352

Cananga odorata 912 918 37 37 — — 12 12 961 955

Adenanthera pavonina 760 765 49 49 12 12 12 12 834 826

Eugenia reinwardtiana 712 687 — — — — — — 712 687

Cycas circinalis — — 610 242 14 14 — — 624 242

Annona muricata 599 429 24 17 — — — — 623 437

Bauhinia monandra 456 459 24 25 — — — — 481 484

Calophyllum inophyllum 356 227 114 76 — — — — 471 301

Ficus tinctoria 304 306 53 31 — — — — 357 306

Mangifera indica — — 37 37 49 38 122 123 208 196

Annona reticulata — — 186 114 14 14 — — 200 126

Macaranga thompsonii — — 86 69 86 59 14 14 186 129

Eugenia thompsonii 178 172 — — — — — — 178 172

Mammea odorata 152 153 24 25 — — — — 176 178

Melanolepis multiglandulosa 152 153 12 12 — — — — 164 165

Chrysophyllum cainito 152 153 — — — — — — 152 153

Tarenna sambucina 152 153 — — — — — — 152 153

Ficus prolixa — — 98 60 24 24 29 28 150 81
33

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Table A2-3—Number of live treesa on forest land by species and diameter class (continued)

Diameter class (inches)

0–4.9 5.0–9.9 10.0–14.9 15.0+ All classes

Scientific name Total SE Total SE Total SE Total SE Total SE

Number of trees (thousands)

Spathodea campanulata — — 49 38 51 30 24 25 124 82

Pisonia grandis — — 61 61 24 25 — — 85 86

Tristiropsis obtusangula — — 75 63 — — — — 75 63

Artocarpus altilis — — 37 20 37 37 — — 73 51

Intsia bijuga — — 39 28 27 18 — — 65 41

Artocarpus mariannensis — — 24 17 12 12 — — 37 20

Barringtonia asiatica — — 24 25 — — 12 12 37 37

Leucaena insularum — — 35 36 — — — — 35 36

Tree unknown — — 27 18 — — — — 27 18

Pandanus dubius — — 25 18 — — — — 25 18

Eugenia palumbis — — 14 14 — — — — 14 14

Glochidion marianum — — 14 14 — — — — 14 14

Barringtonia racemosa — — — — 12 12 — — 12 12

Hernandia sonora — — — — 12 12 — — 12 12

Tabebuia pallida — — 12 12 — — — — 12 12

Note: Totals may be off because of rounding; estimates are subject to sampling error.

SE = sampling error.

a

 Includes all live trees ≥1 inches in diameter at breast height.
34

RESOURCE BULLETIN PNW-RB-270

Table A2-4—Estimated net volume of live treesa on forest land by species group and diameter class (continued)

Diameter class (inches)

5.0–9.9 10.0–14.9 15.0–19.9 20+ All classes

Scientific name Total SE Total SE Total SE Total SE Total SE

Thousand cubic feet

Cocos nucifera 4,444.1 1,612.6 7,457.6 2,807.1 313.7 302.7 — — 12,215.4 4,235.1

Vitex parviflora 3,912.8 1,254.0 4,446.2 1,738.7 739.7 394.6 842.2 721.5 9,940.8 3,425.0

Mangifera indica 83.5 84.1 836.4 622.1 1,784.3 1,795.8 419.7 422.4 3,123.9 2,877.0

Hibiscus tiliaceus 2,881.5 1,105.1 135.3 130.6 — — — — 3,016.8 1,171.3

Heterospathe elata 2,782.9 2,216.5 — — — — — — 2,782.9 2,216.5

Pandanus tectorius 2,273.3 720.1 — — — — — — 2,273.3 720.1

Ficus prolixa 435.9 299.8 78.5 80.0 365.1 352.3 1,346.7 1,299.5 2,226.2 1,736.4

Premna obtusifolia 1,163.1 478.0 231.8 173.7 — — 679.3 655.5 2,074.1 1,086.5

Macaranga thompsonii 478.3 346.3 996.3 637.7 162.8 157.1 — — 1,637.5 1,045.1

Spathodea campanulata 263.8 202.2 813.6 467.9 122.4 123.2 415.3 418.0 1,615.1 1,057.7

Leucaena leucocephala 1,346.4 616.3 — — — — — — 1,346.4 616.3

Casuarina equisetifolia 589.8 409.6 538.5 519.6 — — — — 1,128.3 912.7

Cycas circinalis 1,070.8 458.7 32.5 31.4 — — — — 1,103.3 458.9

Neisosperma oppositifolia 1,001.7 742.4 1.3 1.2 — — — — 1,003.0 742.6

Annona reticulata 546.5 415.5 166.7 160.8 — — — — 713.1 573.7

Artocarpus altilis 86.6 58.0 625.8 629.9 — — — — 712.4 652.0

Aglaia mariannensis 600.3 262.3 — — — — — — 600.3 262.3

Pisonia grandis 273.8 275.6 319.4 321.5 — — — — 593.3 597.1

Intsia bijuga 198.6 138.3 388.1 278.2 — — — — 586.7 342.8

Adenanthera pavonina 146.9 147.9 20.1 20.2 — — 380.8 383.2 547.8 410.7

Cananga odorata 39.2 39.4 — — 385.8 388.3 — — 425.0 388.3

Barringtonia asiatica 144.0 145.0 — — — — 267.9 269.7 412.0 414.6

Tristiropsis obtusangula 276.8 266.9 — — — — — — 276.8 266.9

Calophyllum inophyllum 244.7 161.6 — — — — — — 244.7 161.6

Artocarpus mariannensis 112.9 113.0 128.7 129.5 — — — — 241.5 167.5

Morinda citrifolia 184.0 92.8 — — — — — — 184.0 92.8

Areca catechu 179.5 91.6 — — — — — — 179.5 91.6

Ficus tinctoria 139.4 88.5 — — — — — — 139.4 88.5

Guamia mariannae 138.9 76.9 — — — — — — 138.9 76.9

Hernandia sonora — — 129.1 131.6 — — — — 129.1 131.6

Bauhinia monandra 77.2 77.7 — — — — — — 77.2 77.7

Averrhoa bilimbi 74.9 63.0 — — — — — — 74.9 63.0

Glochidion marianum 56.3 54.3 — — — — — — 56.3 54.3

Pandanus dubius 54.9 40.0 — — — — — — 54.9 40.0
35

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Table A2-4—Estimated net volume of live treesa on forest land by species group and diameter class (continued)

Diameter class (inches)

5.0–9.9 10.0–14.9 15.0–19.9 20+ All classes

Scientific name Total SE Total SE Total SE Total SE Total SE

Thousand cubic feet

Annona muricata 31.9 24.8 — — — — — — 31.9 24.8

Mammea odorata 28.5 28.7 — — — — — — 28.5 28.7

Leucaena insularum 16.7 17.0 — — — — — — 16.7 17.0

Melanolepis multiglandulosa 16.7 16.8 — — — — — — 16.7 16.8

Barringtonia racemosa — — 16.4 16.7 — — — — 16.4 16.7

Eugenia palumbis 12.2 11.8 — — — — — — 12.2 11.8

Tree unknown 10.2 9.0 — — — — — — 10.2 9.0

Tabebuia pallida 4.2 4.3 — — — — — — 4.2 4.3

Note: Totals may be off because of rounding; estimates are subject to sampling error.

SE = sampling error.

a

 Includes all live trees ≥5 inches in diameter at breast height.

Table A2-5—Estimated volume of all live treesa on forest land by diameter class

Diameter class (inches)

5.0–9.9 10.0–14.9 15.0–19.9 20.0+ All sizes

Total SE Total SE Total SE Total SE Total SE

Thousand cubic feet

Net volume 26,423.7 3,287.6 17,362.2 3617.0 3,873.7 1,890.4 4,351.8 1,597.3 52,011.4 6,353.0

Note: Totals may be off because of rounding; estimates are subject to sampling error.

SE = sampling error.

a

 Includes all live trees ≥5 inches in diameter at breast height.
36

RESOURCE BULLETIN PNW-RB-270

Table A2-7—Aboveground biomass of live treesa on forest land by species and diameter class (continued)

Diameter class (inches)

0–4.9 5.0–9.9 10.0–14.9 15+ All classes

Scientific name Total SE Total SE Total SE Total SE Total SE

Thousands of tons

Vitex parviflora 30.9 16.7 138.4 41.5 164.7 70.4 104.2 46.1 438.2 141.0

Cocos nucifera — — 104.8 39.2 198.8 78.8 7.1 6.9 310.7 111.8

Hibiscus tiliaceus 129.9 35.7 114.2 38.8 8.1 7.8 — — 252.2 65.2

Leucaena leucocephala 103.1 34.6 57.5 25.6 — — — — 160.6 52.7

Mangifera indica — — 3.3 3.3 26.1 21.3 90.1 90.7 119.5 114.8

Premna obtusifolia 16.9 11.4 56.6 21.1 9.2 6.6 25.4 24.5 108.2 50.1

Heterospathe elata 22.8 14.2 75.1 58.9 — — — — 97.9 69.0

Aglaia mariannensis 57.9 49.1 20.0 8.3 — — — — 77.8 51.2

Casuarina equisetifolia 26.2 20.6 16.8 10.5 20.5 19.8 — — 63.5 36.3

Spathodea campanulata — — 7.3 5.5 26.2 15.6 24.0 24.2 57.5 38.3

Guamia mariannae 51.6 26.5 5.0 2.8 — — — — 56.6 29.0

Neisosperma oppositifolia 14.0 9.4 28.9 21.5 4.2 4.1 — — 47.1 29.1

Cananga odorata 26.5 26.6 2.1 2.2 — — 15.1 15.2 43.8 31.9

Morinda citrifolia 38.4 17.5 5.3 2.8 — — — — 43.7 18.4

Pandanus tectorius 3.7 2.6 34.2 10.3 — — — — 37.9 11.2

Ficus prolixa — — 6.0 3.8 6.1 6.3 24.9 24.1 37.1 26.2

Adenanthera pavonina 2.6 2.6 4.2 4.2 2.9 2.9 23.8 24.0 33.5 25.4

Macaranga thompsonii — — 7.8 5.7 16.6 10.7 3.7 3.6 28.1 18.0

Averrhoa bilimbi 19.1 14.1 6.2 4.7 — — — — 25.3 18.8

Cycas circinalis — — 23.1 9.9 2.0 1.9 — — 25.1 10.1

Triphasia trifolia 24.9 20.9 — — — — — — 24.9 20.9

Intsia bijuga — — 7.7 5.4 16.0 11.3 — — 23.7 14.1

Table A2-6—Aboveground biomass and carbon of live a and dead treesb on forest land by diameter class

Diameter class (inches)

5.0–9.9 10.0–14.9 15.0–19.9 20+ All classes

Total SE Total SE Total SE Total SE Total SE

Thousands of tons

Live tree biomass 776.0 92.6 524.6 111.3 174.7 81.2 157.7 50.1 2,267.0 233.3

Dead tree biomass 21.3 4.7 8.9 6.8 — — — — 30.3 8.8

Live tree carbon 388.0 46.3 262.3 55.7 87.4 40.6 78.9 25.1 1,133.5 116.7

Dead tree carbon 10.7 2.4 4.5 3.4 — — — — 15.2 4.4

Note: Totals may be off because of rounding; estimates are subject to sampling error.

SE = sampling error; 

a

 Includes all live trees ≥1 inches in diameter at breast height (d.b.h.); biomass of live trees 1 to 4.9 inches in diameter are not shown here.

b

 Includes all dead trees ≥5 inches d.b.h.; smaller dead trees were not measured in this inventory.
37

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Table A2-7—Aboveground biomass of live treesa on forest land by species and diameter class (continued)

Diameter class (inches)

0–4.9 5.0–9.9 10.0–14.9 15+ All classes

Scientific name Total SE Total SE Total SE Total SE Total SE

Thousands of tons

Areca catechu 15.3 11.2 6.3 3.3 — — — — 21.6 11.7

Annona reticulata — — 17.6 11.6 3.7 3.6 — — 21.3 15.0

Artocarpus altilis — — 4.5 2.8 14.2 14.3 — — 18.8 15.4

Barringtonia asiatica — — 3.5 3.5 — — 13.9 14.0 17.4 17.5

Bauhinia monandra 13.7 13.8 1.9 1.9 — — — — 15.6 15.7

Tristiropsis obtusangula — — 11.6 9.8 — — — — 11.6 9.8

Ochrosia mariannensis 10.3 10.0 — — — — — — 10.3 10.0

Calophyllum inophyllum 1.5 1.0 7.6 5.0 — — — — 9.1 5.9

Pisonia grandis — — 4.1 4.2 4.4 4.4 — — 8.5 8.5

Mammea odorata 5.2 5.3 1.5 1.5 — — — — 6.8 6.8

Eugenia reinwardtiana 6.5 6.3 — — — — — — 6.5 6.3

Maytenus thompsonii 5.8 5.6 — — — — — — 5.8 5.6

Artocarpus mariannensis — — 2.0 1.4 3.4 3.5 — — 5.5 3.7

Annona muricata 3.1 2.2 1.2 0.8 — — — — 4.2 2.8

Hernandia sonora — — — — 3.9 4.0 — — 3.9 4.0

Ficus tinctoria 0.8 0.8 3.0 1.6 — — — — 3.8 1.8

Leucaena insularum — — 2.8 2.8 — — — — 2.8 2.8

Barringtonia racemosa — — — — 2.4 2.5 — — 2.4 2.5

Eugenia thompsonii 2.4 2.3 — — — — — — 2.4 2.3

Tree unknown — — 1.4 1.0 — — — — 1.4 1.0

Glochidion marianum — — 1.2 1.1 — — — — 1.2 1.1

Tabebuia pallida — — 0.8 0.8 — — — — 0.8 0.8

Eugenia palumbis — — 0.7 0.6 — — — — 0.7 0.6

Melanolepis multiglandulosa 0.3 0.3 0.4 0.4 — — — — 0.7 0.7

Pandanus dubius — — 0.7 0.5 — — — — 0.7 0.5

Chrysophyllum cainito 0.5 0.5 — — — — — — 0.5 0.5

Tarenna sambucina 0.2 0.2 — — — — — — 0.2 0.2

Note: Totals may be off because of rounding; estimates are subject to sampling error.

SE = sampling error.

a

 Includes all live trees ≥1 inches in diameter at breast height.
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Table A2-8—Average understory vegetation cover and number of Forest Inventory and Analysis subplots 

where the species occurred

Scientific name

Average 

cover

Number of 

subplots 

Percent

Saccharum spontaneum 41.8 13

Epipremnum pinnatum 41.0 5

Bauhinia monandra 40.0 1

Antigonon leptopus 39.1 9

Miscanthus floridulus 37.5 48

Urochloa maxima 35.5 11

Musa 31.0 2

Bambusa vulgaris 30.0 2

Telosma 30.0 1

Tradescantia spathacea 30.0 1

Bothriochloa bladhii 29.4 23

Heterospathe elata 25.8 12

Casuarina equisetifolia 25.6 5

Gleichenia linearis 25.0 1

Hibiscus tiliaceus 23.1 59

Guamia mariannae 23.0 29

Triphasia trifolia 22.6 19

Aglaia mariannensis 22.3 14

Tarenna sambucina 21.5 2

Leucaena leucocephala 21.2 49

Tabebuia heterophylla 20.5 2

Dicranopteris linearis 20.3 15

Colubrina asiatica 20.3 12

Freycinetia reineckei 20.2 9

Neisosperma oppositifolia 20.0 4

Ochrosia mariannensis 20.0 4

Sorghum halepense 20.0 1

Teramnus labialis 20.0 2

Averrhoa bilimbi 19.4 8

Cocos nucifera 18.4 20

Flagellaria indica 18.0 27

Nephrolepis hirsutula 18.0 41

Curcuma longa 17.2 5

Syngonium podophyllum 16.3 3

Ochrosia oppositifolia 16.3 10

Pennisetum polystachion 16.1 24

Annona reticulata 15.9 7

Scientific name

Average 

cover

Number of 

subplots 

Percent

Abelmoschus moschatus 15.0 1

Vitex parviflora 14.5 33

Nephrolepis biserrata 14.1 19

Pandanus dubius 14.0 2

Medinilla medinilliana 13.3 7

Scleria polycarpa 13.3 8

Annona squamosa 13.0 1

Flemingia strobilifera 13.0 9

Jasminum marianum 13.0 3

Morinda citrifolia 13.0 37

Areca catechu 12.5 13

Adenanthera pavonina 12.5 2

Pandanus tectorius 12.3 35

Rhynchospora rubra 12.3 11

Phymatosorus scolopendria 12.1 22

Phragmites karka 12.0 4

Cananga odorata 11.0 1

Thelypteris pennata 11.0 1

Premna obtusifolia 10.9 17

Maytenus thompsonii 10.3 3

Annona muricata 10.0 7

Citrus × limon 10.0 1

Cynodon dactylon 10.0 1

Melanolepis multiglandulosa 10.0 1

Melochia villosissima var.

compacta

10.0 1

Microlepia speluncae 10.0 1

Thelypteris opulenta 10.0 1

Wikstroemia elliptica 9.7 3

Oplismenus hirtellus 9.5 6

Bidens alba 9.1 8

Eugenia thompsonii 9.0 2

Mikania micrantha 9.0 21

Spathodea campanulata 9.0 2

Calophyllum inophyllum 8.8 5

Cestrum diurnum 8.5 4

Oplismenus compositus 8.4 8
39

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

Table A2-8—Average understory vegetation cover and number of Forest Inventory and Analysis subplots 

where the species occurred (continued)

Scientific name

Average 

cover

Number of 

subplots 

Percent

Barringtonia racemosa 8.0 2

Dimeria chloridiformis 8.0 11

Plumeria obtusa var. obtusa 8.0 1

Fimbristylis tristachya 7.7 9

Stylosanthes guianensis 7.7 3

Ficus microcarpa 7.5 2

Lycopodiella cernua var. cernua 7.5 6

Scaevola sericea 7.5 2

Thelypteris parasitica 7.5 2

Lygodium scandens 7.4 10

Cycas circinalis 7.0 2

Ipomoea pes-caprae ssp. 

brasiliensis

7.0 1

Entada pursaetha 6.8 9

Mucuna pruriens 6.8 4

Stictocardia tiliifolia 6.4 8

Sphagneticola trilobata 6.2 5

Acacia confusa 6.0 1

Alocasia macrorrhizos 6.0 1

Artocarpus altilis 6.0 1

Eugenia reinwardtiana 6.0 2

Ficus tinctoria 6.0 4

Melastoma malabathricum var.

mariannum

6.0 1

Scaevola sericea var. taccada 6.0 1

Chromolaena odorata 5.9 14

Centotheca latifolia 5.0 1

Ipomoea pes-caprae 5.0 1

Ixora triantha 5.0 3

Senna tora 5.0 1

Sida rhombifolia 5.0 1

Hyptis capitata 5.0 26

Carica papaya 4.8 5

Fimbristylis dichotoma 4.8 4

Glochidion marianum 4.3 6

Polypodium punctatum 4.2 20

Waltheria indica 4.2 5

Averrhoa carambola 4.0 1

Scientific name

Average 

cover

Number of 

subplots 

Percent

Hyptis rhomboidea 4.0 3

Mangifera indica 4.0 1

Miconia punctata 4.0 1

Passiflora foetida 4.0 4

Tecoma stans 4.0 1

Vigna adenantha 4.0 1

Pyrrosia lanceolata 3.8 6

Melastoma malabathricum 3.5 2

Passiflora suberosa 3.3 3

Arundina graminifolia 3.3 12

Abrus precatorius 3.0 1

Acacia mangium 3.0 1

Alocasia cucullata 3.0 1

Asplenium nidus 3.0 1

Cerbera dilatata 3.0 1

Discocalyx megacarpa 3.0 1

Eleusine indica 3.0 1

Imperata conferta 3.0 1

Lygodium microphyllum 3.0 3

Malvastrum coromandelianum 3.0 1

Mimosa pudica 3.0 2

Myrtella bennigseniana 3.0 1

Paspalum paniculatum 3.0 1

Pennisetum polystachion ssp.

setosum

3.0 1

Psidium guajava 3.0 1

Pteris tripartita 3.0 2

Samanea saman 3.0 1

Spathoglottis plicata 3.0 1

Stachytarpheta jamaicensis 3.0 2

Thelypteris maemonensis 3.0 1

Thelypteris unita 3.0 2

Tristiropsis obtusangula 3.0 2

Wedelia 3.0 1
40

RESOURCE BULLETIN PNW-RB-270

Glossary

abiotic—Pertaining to nonliving factors such as temperature, moisture, and wind. 

aerial photography—Imagery acquired from an aerial platform (typically aircraft 

or helicopter) by means of a specialized large-format camera with well-defined 

optical characteristics. The geometry of the aircraft orientation at the time of image acquisition is also recorded. The resultant photograph will be of known scale, 

positional accuracy, and precision. Aerial photography for natural resource use is 

usually either natural color or color-infrared, and is film-based or acquired using 

digital electronic sensors.

aspect—Compass direction that a slope faces. 

biodiversity—Variety and variability among living organisms and the ecological 

complexes in which they occur. Diversity can be defined as the number of different 

items and their relative frequencies. https://www.epa.gov/enviroatlas/enviroatlasbenefit-category-biodiversity-conservation. (27 October 2019). 

biomass—The aboveground weight of wood and bark in live trees 1.0 inch in diameter at breast height (d.b.h.) and larger from the ground to the tip of the tree, excluding all foliage. The weight of wood and bark in lateral limbs, secondary limbs, and 

twigs under 0.5 inch in diameter at the point of occurrence on sapling-size trees is 

included in the measure, but is excluded on poletimber- and sawtimber-size trees. 

Biomass is typically expressed as green oven-dry weight in tons (USDA FS 2006).

bole—Trunk or main stem of a tree. 

damage—Damage to trees caused by biotic agents such as insects, diseases, and 

animals or abiotic agents such as weather, fire, or mechanical equipment. 

diameter at breast height (d.b.h.)—The diameter of a tree stem, located 4.5 ft 

above the ground (breast height) on the uphill side of a tree. The point of diameter 

measurement may vary on abnormally formed trees (USDA FS 2006).

disturbance—Any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the 

physical environment (Helms 1998). 

down woody material (DWM)—Dead material on the ground in various stages 

of decay. It includes coarse and fine wood material. Previously named down woody 

debris (DWD). https://www.nrs.fs.fed.us/fia/data-tools/state-reports/glossary/default.

asp (27 October 2019).
41

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

ecosystem—A spatially explicit, relatively homogeneous unit of the Earth that includes all interacting organisms and components of the abiotic environment within 

its boundaries. An ecosystem can be of any size: a log, a pond, a field, a forest, or 

the Earth’s biosphere (Helms 1998). 

elevation—Height above a fixed reference point, often the mean sea level. 

erosion—The wearing away of the land surface by running water, wind, ice, or 

other geological agents.

fixed-radius plot—A circular sampled area with a specified radius in which all 

trees of a given size, shrubs, and other items are tallied (USDA FS 2006).

forb—A broad-leaved herbaceous plant, as distinguished from grasses, shrubs, and 

trees (USDA FS 2006).

forest land—Land that is at least 10 percent tree cover by forest trees of any size, 

or land formerly having such tree cover, and not currently developed for a nonforest 

use (USDA FS 2006). 

forest type—A classification of forest land based on and named for the tree species 

that forms the plurality of live-tree cover that are not overtopped (USDA FS 2006). 

These forest types are also called forest communities and are delineated by the classification guide outlined in Mueller-Dombois and Fosberg (1998).

forest type group—A combination of forest types that share closely associated 

species or site requirements (USDA FS 2006).

graminoid—Grasses (family Gramineae or Poaceae) and grass-like plants such as 

sedges (family Cyperaceae) and rushes (family Juncaceae). 

grassland—Land on which the vegetation is dominated by grasses, grass-like 

plants, or forbs.

invasive plant—A plant that is not native to the ecosystem under consideration and 

that causes or is likely to cause economic or environmental harm or harm to human, 

animal, or plant health. http://www.invasivespeciesinfo.gov/docs/council/isacdef.

pdf. (5 January 2015).

live trees—All living trees, including all size classes, all tree classes, and both 

commercial and noncommercial species listed in the Forest Inventory and Analysis 

(FIA) field manual (USDA FS 2006).

mortality—The death of trees from natural causes, or subsequent to incidents such 

as storms, wildfire, or insect and disease epidemics (Helms 1998).
42

RESOURCE BULLETIN PNW-RB-270

native species—Plant species that were native to an American region prior to EuroAmerican settlement. For vascular plants, they are the species that are not present 

on the USDA Natural Resources Conservation Service list of nonnative species (see 

nonnative species) (USDA NRCS 2000).

nonforest land—Land that has never supported forests or formerly was forested 

and currently is developed for nonforest uses. Included are lands used for agricultural crops, residential areas, and constructed roads. The area must be at least 1.0 ac 

and 120.0 ft wide. 

nonnative species—Plant species that were introduced to America subsequent to 

Euro-American settlement. Nonnative vascular plants are present on the USDA Natural 

Resources Conservation Service list of nonnative species (USDA NRCS 2000).

nontimber forest products (NTFP)—Species harvested from forests for reasons 

other than production of timber commodities. 

ownership—A legal entity having an ownership interest in land, regardless of the 

number of people involved. An ownership may be an individual; a combination of 

persons; a legal entity such as corporation, partnership, club, or trust; or a public 

agency. An ownership has control of a parcel or group of parcels of land (USDA 

FS 2006).

pathogen—An organism or virus directly capable of causing disease or mortality.

regeneration—The established progeny from a parent plant, seedlings or saplings 

existing in a stand, or the act of renewing tree cover by establishing young trees 

naturally or artificially. May be artificial (direct seeding or planting) or natural 

(natural seeding, coppice, or root suckers) (adapted from Helms 1998). 

remote sensing—Capture of information about the Earth from a distant vantage 

point. The term is often associated with satellite imagery but also applies to aerial 

photography, airborne digital sensors, ground-based detectors, and other devices. 

reserved forest land—Land permanently reserved from wood products utilization 

through statute or administrative designation. Examples include national forest wilderness areas and national parks and monuments (USDA FS 2006). 

sampling error—Difference between a population value and a sample estimate that 

is attributable to the sample, as distinct from errors due to bias in estimation, errors 

in observation, etc. Sampling error is measured as the standard error of the sample 

estimate (Helms 1998). 

sapling—A live tree 1.0 to 4.9 inches in diameter (USDA FS 2006).
43

American Samoa’s Forest Resources: Forest Inventory and Analysis, 2012

seedlings—Live trees <1.0 inch d.b.h. and at least 6 inches in height (softwoods) or 

12 inches in height (hardwoods) (USDA FS 2006). 

shrub—Perennial, multistem woody plant, usually less than 13 to 16 ft in height, 

although under certain environmental conditions shrubs may be single-stem or 

taller than 16 ft. Includes succulents (e.g., cacti) (USDA FS 2006). 

slope—Measure of change in surface value over distance, expressed in degrees or 

as a percentage (Helms 1998).

snag—Standing dead tree ≥5 inches d.b.h. and ≥4.5 ft in length, with a lean of <45 

degrees. Dead trees leaning more than 45 degrees are considered to be down woody 

material. Standing dead material shorter than 4.5 ft are considered stumps (USDA 

FS 2006). 

species group—A collection of species used for reporting purposes (USDA FS 2006).

stand-size class—A classification of stands based on tree size. Large-diameter 

stands have the majority of trees at least 11.0 inches d.b.h. for hardwoods and 9.0 

inches d.b.h. for softwoods; medium-diameter stands have the majority of trees at 

least 5.0 inches d.b.h. but not as large as large-diameter trees; and small-diameter 

stands have the majority of trees less than 5.0 inches d.b.h.

stratification—A statistical tool used to reduce the variance of the attributes 

of interest by partitioning the population into homogenous strata (Bechtold and 

Patterson 2005). 

succession—The gradual supplanting of one community of plants by another 

(Helms 1998).

terrestrial—Of or relating to the Earth or its inhabitants; of or relating to land as 

distinct from air or water. http://www. merriam-webster.com/dictionary/terrestrial. 

(5 January 2015).

tree—A woody perennial plant, typically large, with a single well-defined stem 

carrying a more or less definite crown; sometimes defined as attaining a minimum 

diameter of 3 inches and a minimum height of 15 ft at maturity. For FIA, any plant 

on the tree list in the current field manual is measured as a tree (USDA FS 2006). 

understory—All forest vegetation growing under an overstory (Helms 1998). 

unreserved forest land—Forest land that is not withdrawn from harvest by statute 

or administrative regulation. Includes forest lands that are not capable of producing 

in excess of 20 ft3

/ac per year of industrial wood in natural stands (Smith et al. 2004).



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