American Samoa’s 

Forest Resources, 2001

Joseph A. Donnegan, Sheri S. Mann, 

Sarah L. Butler, and Bruce A. Hiserote

United States

Department of

Agriculture

Forest 

Service

Pacific Northwest

Research Station

Resource Bulletin

PNW-RB-244

November 2004
The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of 

multiple use management of the Nation’s forest resources for sustained yields of wood, 

water, forage, wildlife, and recreation. Through forestry research, cooperation with the 

States and private forest owners, and management of the National Forests and National 

Grasslands, it strives—as directed by Congress—to provide increasingly greater service to 

a growing Nation.

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activities on the basis of race, color, national origin, gender, religion, age, disability, political 

beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all 

programs.) Persons with disabilities who require alternative means for communication of 

program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET 

Center at (202) 720-2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326-

W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 20250-9410 or 

call (202) 720-5964 (voice and TDD). USDA is an equal opportunity provider and employer.

USDA is committed to making its information materials accessible to all USDA customers 

and employees.

Authors

Joseph A. Donnegan is an ecologist, Sarah L. Butler is an ecologist, Bruce A. 

Hiserote is an information technology specialist, Forestry Sciences Laboratory, 

620 SW Main Street, Suite 400, Portland, OR 97205-3028; Sheri S. Mann was the 

territorial forester, American Samoa Forestry, Pago Pago, American Samoa 96799. 

Mann now works as a cooperative resource management forester for the State of 

Hawaii, Division of Forestry and Wildlife, Department of Land and Natural Resources, 1151 Punchbowl Street, Room 325, Honolulu, HI 96813.
Abstract

Donnegan, Joseph A.; Mann, Sheri S.; Butler, Sarah L.; Hiserote, Bruce A. 

2004. American Samoa’s forest resources, 2001. Resour. Bull. PNW-RB-244. 

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 32 p.

The Forest Inventory and Analysis Program of the Pacific Northwest Research 

Station collected, analyzed, and summarized data from field plots, and mapped 

land cover on four islands in American Samoa. This statistical sample provides 

estimates of forest area, stem volume, biomass, numbers of trees, damages to 

trees, and tree size distribution. The summary provides detailed tables and 

graphical highlights to help inform resource managers and policymakers, as 

well as educating the public regarding the status and trends in their natural 

resources.

Keywords: American Samoa, biomass, damage, FIA, forest inventory, 

timber volume.
Summary

The Pacific Northwest Research Station Forest Inventory and Analysis (FIA) Program conducted a forest inventory on American Samoa to assess forest area, stem 

volume and biomass, tree damages, and associated understory vegetation. Twentyone field plots were sampled by FIA and American Samoa foresters on the islands 

of Tutuila, Ta’u, Olosega, and Ofu. Land cover was mapped from high-resolution 

satellite imagery to stratify the field sample. Total forest area, including agroforest, 

was estimated to be 43,631 acres, or approximately 90.1 percent of the land area 

on these islands. Approximately 7 percent of the land cover is urban, the majority 

occurring on Tutuila. Gross stem volume was estimated as about 72 million cubic 

feet, inclusive of all size classes. The aboveground stem weight for trees at least 5 

inches in diameter was estimated to be 1.1 million tons. Approximately 17 percent 

of the trees sampled had some form of damage, with the dominant damages being 

open wounds. Where the damaging agent could be identified, the primary causes 

were weather (25 percent) and insects (15 percent). In one-third of the cases of 

damage, a primary damaging agent could not be positively identified. Fifty tree 

species and 86 understory species were measured on 21 sixth-acre plots.
1

American Samoa’s Forest Resources, 2001

Introduction

This summary of forest resources on the islands of American Samoa (fig. 1) is based 

on a pilot inventory, conducted in 2001, to test field data collection methods in the 

tropical Pacific. The USDA Forest Service, Pacific Northwest Research Station Forest Inventory and Analysis Program (FIA) in cooperation with Pacific Island foresters uses the inventory to help answer local and national questions about the status 

and trends in tropical forests. The fieldwork for this project was conducted primarily 

by American Samoa foresters with assistance from two mainland FIA foresters, 

which allowed the exchange of skills among cultures and agencies.

The FIA Program conducts a systematic, sample-based, field inventory across 

all ownerships in the Pacific Islands on a periodic basis. Prior inventory work in 

American Samoa (Cole et al. 1988) concentrated on developing a vegetation type 

map and assessing tree volumes for forest types. The current effort estimates the 

area of forest types, tree size distribution, volume, biomass, rooting and crown 

characteristics, and damages for living and dead trees. The inventory helps resource 

managers define the extent, size distribution, and species composition of their forested and nonforested lands, and after remeasurement, the change in their resources. 

Empirically based knowledge of the status and trends in forest vegetation can help 

managers plan sustainable supplies of wood, control invasive species, control erosion, and manage disturbances such as fire and animal damage.

Objectives:

1. Test adapted FIA data collection and analysis methods in the tropical 

Pacific Islands.

2. Estimate the area of forest land by stand size class.

3. Estimate the volume, biomass, and carbon storage for trees by species 

and diameter class.

4. Estimate the numbers of trees that have died and those affected by 

insects and disease.

5. Share measurement and analysis techniques among groups involved in 

the inventory.

Methods

Site Description

American Samoa is a group of five volcanic islands, Tutuila, Aunu’u, Ta’u, Olosega 

and Ofu, and two coral atolls, Rose and Swains. The volcanic islands are topographically complex with steep rugged terrain. Slopes exceeding 70 percent occur 
2

RESOURCE BULLETIN PNW-RB-244

on about half of the volcanic landmass (Nakamura 1984). Mount Lata, on Ta’u, is 

the highest point in American Samoa reaching 3,166 feet in elevation. On the largest island in the group, Tutuila, Mount Matafao reaches a height of 2,142 feet. The 

climate is hot and humid with little variation in temperature annually and diurnally, 

but with a pronounced dry season lasting June through September (fig. 2).

Natural disturbances in American Samoa include hurricanes, past volcanic 

eruptions, and soil erosion. Hurricane frequency is moderate as American Samoa 

is east of the most active hurricane-producing storm tracks. Erosion is prevalent in 

deep volcanic soils on steep, cleared slopes. Humans have cleared forest, primarily 

on the lower, gentler slopes, and contributed to ecosystem disturbance by introducing nonnative plants, animals, insects, and diseases. The upland rain forest has also 

been logged on sites where soils permit agricultural use (Mueller-Dombois and 

Fosberg 1998).

Figure 1—American Samoa is in the south-central Pacific Ocean, approximately 4,600 miles southwest of Los Angeles, California.
3

American Samoa’s Forest Resources, 2001

74

76

78

80

82

84

86

88

6

8

10

12

14

16

Average Maximum and Minimum Temperature

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

Monthly Precipitation Totals

Month

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

Precipitation (inches)

Pago Pago, American Samoa, 1966–2001

Temperature (°F)

4

Figure 2—Average maximum and minimum temperature, and total monthly precipitation for Pago Pago, American Samoa. 

Note the pronounced seasonality in precipitation (Western Regional Climate Center, http://www.wrcc.dri.edu/cgi-bin/cliMAIN.

pl?pipago).
4

RESOURCE BULLETIN PNW-RB-244

The government of American Samoa leases 9,000 acres on three islands (8,000 

terrestrial, 1,000 aquatic) to the U.S. Department of the Interior, National Park 

Service. This park was established in 1988 with the lease extending for 50 years.

Vegetation Types

Mueller-Dombois and Fosberg (1998) recognize seven distinct categories of vegetation in American Samoa: littoral vegetation, wetland vegetation, lowland rain forest, 

montane rain forest, cloud forest and scrub, vegetation on recent volcanic surfaces, 

and modified vegetation. Each category is briefly described below including forest 

and community types found within them, following Whistler (1992). The FIA inventory does not provide sufficient plot density to reliably classify vegetation types 

in these highly diverse tropical forests, but provides plot-level data to help refine 

remotely sensed estimates of forest type acreage and developmental stage. Some of 

the species named in the vegetation descriptions did not occur on the sample of FIA 

field plots.

Littoral vegetation—

Littoral vegetation is coastal vegetation growing on well-drained substrates and 

lava rock, excluding mangrove and coastal lowland vegetation. Community types 

include herbaceous strand, littoral scrub, Pandanus scrub, and littoral forest. Plant 

communities have adapted to the harsh environment of salt spray and the coarse, 

low-nutrient soils. Thespesia populnea (L.) Soland. ex Correa is commonly found 

in the littoral zone. Littoral vegetation helps stabilize coastal areas and helps protect 

soils from erosion as well as filtering runoff back to the ocean.

Wetland vegetation—

Wetland vegetation is vegetation growing in saturated lowland flats and mangroves. 

Community types include mangrove scrub and forest, swamp forest, coastal marsh, 

and montane marsh and bog. Barringtonia samoensis is a common species found 

in the freshwater marshes and was once prized for boat masts (see table 1 for common names of trees and species authorities). Hibiscus tiliaceus often surrounds 

marshlands. Mangroves in American Samoa are dominated by three tree species, 

Rhizophora mangle, Bruguiera gymnorrhiza (L.) Lam., and Xylocarpus moluccensis (Imk.) Roem. Ferns are common here as well. The wetland vegetation, like the 

littoral, acts to protect soils from erosion and acts as a sediment trap for runoff.

Lowland rain forest—

Lowland rain forest is low-elevation forest characterized by several distinct species 

assemblages (see Mueller-Dombois and Fosberg 1998). Community types are based 

on dominant species and include Diospyros forest, Dysoxylum forest, Pometia
5

American Samoa’s Forest Resources, 2001

Table 1—Scientific and common names, and estimated specific gravities a of species measured 

as trees in American Samoa

Scientific name Common name

Specific

gravity

Number

measured

Adenanthera pavonina L. lopa 0.50 3

Aglaia samoensis A. Gray — .50 3

Alphitonia zizyphoides A. Gray toi .50 14

Artocarpus altilis (Park.) Fosb. — .50 10

Barringtonia samoensis A. Gray futu .50 8

Bischofia javanica Bl. ‘o’a .54 7

Buchanania merrillii Christorph. — .50 3

Calophyllum neo-ebudicum Guillaum. tamanu .50 2

Cananga odorata Hook. f. moso’oi .29 23

Canarium ovatum Engler pili nut .50 1

Canarium vitiense A. Gray ma’ali .54 4

Cassia fistula L. golden shower .71 3

Castilla elastica Sessé pulu mamoe .50 5

Cocos nucifera L. niu .50 38

Cyathea lunulata (Forst. f.) Copel. olioli .50 48

Cyathea spp. Sm. treefern .50 4

Diospyros samoensis A. Gray auli .50 4

Dysoxylum maota Reinecke maota .50 34

Dysoxylum samoense A. Gray mamala .50 2

Elaeocarpus ulianus Christoph. — .50 25

Elattostachys falcata (A. Gray) Radlk. taputo’i .50 1

Erythrina fusca Lour. lalapa .25 2

Erythrina variegata L. gatae .50 1

Ficus obliqua Forst. f. aoa .50 1

Ficus scabra Forst. f. — .50 2

Flacourtia rukam var. micronesica Fosb. & Sachet filimoto .50 6

Garcinia myrtifolia A.C. Smith — .65 1

Hernandia nymphaeifolia (Presl.) Kub. pu’a, Chinese lantern .50 7

Hibiscus tiliaceus L. fau .57 85

Inocarpus fagifer (Park.) Fosb. ifi .50 9

Kleinhovia hospita L. fu’afu’a .36 5

Macaranga grayana Muell. Arg. — .50 2

Macaranga harveyana (Muell. Arg.) Muell. Arg. lau pata .50 10

Mangifera indica L. — .52 1

Morinda citrifolia L. nonu .50 6

Myristica fatua Houtt. ‘atone .50 61

Neisosperma oppositifolia (Lam.) Fosb. & Sachet fao .50 5

Neonauclea forsteri Merr. afa .50 8

Omalanthus nutans (J.G. Forst.) Guill. fanuamamala .50 1

Pipturus argenteus (Forst.) Wedd. soga .50 8

Pisonia grandis R. Br. pu’avai .50 1

Planchonella garberi Christoph. ‘ala’a .50 4

Planchonella torricellensis (K. Schum.) Lam. — .50 2

Psychotria insularum A. Gray matalafi .50 2
6

RESOURCE BULLETIN PNW-RB-244

forest, Syzygium forest, and Planchonella (Pouteria) forest. Tree species that are 

highly valued for their wood are found here and include Pometia pinnata J.R. & 

J.G. Forst., Syzygium inophylloides, and Calophyllum neo-ebudicum. Lowland 

rain forests occur on ridges, slopes, in valleys, and on lowland lava flows. Drier 

forest types are found on ridges and slopes. Extensive lowland lava flow forest 

once existed on the Tafuna plains of Tutuila, but except for 40 acres, it has been 

replaced largely by urban development and coconut plantations. As the market 

for coconut has dropped off, the plantations have been abandoned and are slowly 

converting to secondary vegetation with mixed agroforest.

Montane rain forest—

Montane rain forest is high-elevation, often steeply sloped forest (>1,640 feet) 

characterized by high precipitation. The dominant canopy species is the native 

Dysoxylum huntii Merr. ex Setchell. No community types are differentiated by 

Whistler (1992) for this category. The higher elevation forests tend to be less 

impacted by severe weather. The steep slopes inhibit cultivation.

Cloud forest and scrub—

Limited to the highest elevations on Ta’u and Olosega in American Samoa, this 

forest type is cooler and wetter than montane rain forest and dominated by tree 

ferns given sufficient recovery time following hurricanes. No community types are 

defined by Whistler (1992). The endemic Reynoldsia plesosperma A. Gray is the 

dominant tree form in these forests. Cloud forest is generally blanketed by clouds 

and mist, enabling a thick layer of mosses and epiphytes to grow on most surfaces.

Vegetation on recent volcanic surfaces—

Pioneer rain forest vegetation occurring on recent lava flows includes lowland 

volcanic scrub and upland volcanic scrub community types.

Scientific name Common name

Specific

gravity

Number

measured

Rhizophora mangle L. togo .50 12

Rhus taitensis Guillem. tavai .50 32

Scaevola taccada (Gaertn.) Roxb. to’ito’i .50 3

Sterculia fanaiho Setchell fana’io .50 1

Syzygium inophylloides C. Muell. asi .50 6

Syzygium samarangense (Bl.) Merr. & Perry nonu vao .50 1

Syzygium samoense (Burk.) Whistler fena vao .50 1

aSpecific gravity was used to calculate biomass and carbon mass.

Table 1—Scientific and common names, and estimated specific gravities a of species measured 

as trees in American Samoa (continued)
7

American Samoa’s Forest Resources, 2001

Modified vegetation—

Vegetation types that arise from human-caused changes in growing conditions, 

disturbance regimes, or other manipulations. Community types include secondary 

scrub, secondary forest, fernland, and managed land.

Field Methods

This inventory is based on the national FIA inventory (USDA Forest Service 2003) 

conducted on the mainland United States across all ownerships and forest types. 

Adaptations were made to the national design to include additional branching and 

rooting forms, a topographically based index of site productivity, additional tree 

crown measurements, and the inclusion of special interest species ranging from invasive plants, to pathogens, to culturally or economically important species of various life forms. In the mainland FIA program, plots are spaced within forest land 

on a 3.3-mile grid. With the active assistance of the American Samoa Community 

College, Community and Natural Resources, Forestry Division, plots were spaced 

across all vegetation types at 1.9-mile intervals, yielding a triple intensification of 

the mainland inventory plot grid.

The FIA plot cluster is composed of four 24-foot-radius subplots. Three of 

those subplots are equally spaced, as if on spokes of a wheel, around the central 

subplot (fig. 3). The distance from the middle of the central subplot to the middle 

of each subplot on the three spokes is 120 feet.

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

Forest Service 2002). Differences in forest-type conditions are also mapped. For 

example, roads that intersect subplots are mapped, as are clear boundaries in forest 

size classes. The 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, epiphytic loadings, crown characteristics, tree locations, and regeneration information. The field data for this inventory 

was collected over a 7-month period, starting May 2001.

Analysis Methods

The FIA program defines different land categories (strata) across a landscape by 

using aerial photography or satellite imagery. The simplest stratification is separating land into forest and nonforest. However, stratifications can be assisted or refined 

by using ancillary data, such as topography, soils information, life zone or climate 

information, and prior inventories of vegetation groups.

The American Samoa land-cover stratification was conducted via a classification of IKONOS satellite data. Cloud cover on the interior of the islands was 

masked out and replaced with pieces of a vegetation map produced in 1988 from 
8

RESOURCE BULLETIN PNW-RB-244

aerial photography. The initial classification divided the landscape into forest, 

urban, nonforest vegetation, barren, and water land types. Ten percent cover of 

trees was used as the basis for the forest land classification and includes both 

agroforests and mangrove forests. Nonforest vegetation includes other vegetation 

types with less than 10 percent cover of trees. The acreage each field plot represents was derived by dividing the total acreage of forest by the number of field 

plots falling within the geographic bounds of that specific land cover. Mean stand 

size is expanded to the landscape level by using the same expansion factors.

Wood volume was estimated for individual trees by using tree height and 

two stem diameter measurements. These measurements are expanded to volume 

Forest Inventory and Analysis

Pacific Islands Plot Design

N

Overall plot footprint ~1.5 acres

Distance between subplot centers: 120 feet

Distance from subplot center to microplot center: 12 feet

1

2

4 3

Plot

Subplot Microplot

6.8-foot-radius microplot: 

 seedlings + saplings

Key

24-foot-radius subplot: 

 all trees (�5 inches in 

 diameter at breast height)

Figure 3—Forest Inventory and Analysis Pacific Islands plot design.
9

American Samoa’s Forest Resources, 2001

estimates by using equations for sections of a cone. Biomass for individual tree 

stems is estimated by using the specific gravity for known species (11 out of 51 

species measured on American Samoa have known specific gravities). For species 

where specific gravity is not known, an average specific gravity, according to island 

group, is used. Figures for aboveground tree biomass are estimated by using bole 

volume and do not include branch, foliage, or root biomass.

An additive combination of relative density and relative basal area (importance 

value) is used to classify forest types and assess species dominance in a stand. Site 

productivity estimates traditionally require forest stand age, derived from the annual 

rings of forest trees. Because tropical trees do not produce consistent annual rings, 

a modified topographic relative moisture index (TRMI) (Parker 1982) was used 

as a proxy for site productivity. The TRMI used a weighted, additive combination 

of slope steepness, slope shape, and slope position to assess the potential moisture 

channeling to a forest stand. Although moisture is not likely to be the only factor 

limiting tree growth, here it serves as a proxy for productivity until we can obtain 

remeasurement data for forest productivity.

Reliability of FIA Data

The area of land cover types mapped from the IKONOS classification is assumed 

to be accurate and is used as the basis for the expansion of the numbers of trees, 

tree volume, and tree biomass from the plot scale to the forest-type scale. Possible 

sources of error not accounted for in our estimates include errors in the land cover 

map owing to incorrect interpretation of the image, errors from rounding when 

working with pixel-based imagery, and measurement errors on field plots. Standard 

errors for the expansion of our estimates from field plots to the forested landscape 

were calculated according to the proportion of area occupied by forest. Forest area 

was treated as known rather than estimated, and variance was calculated by using 

methods in Cochran (1977). With one standard error as our basis for evaluation, 

there is a 68-percent chance that the true total gross stem volume (trees >5 inches 

diameter at breast height) on American Samoa lies between 59,798,356 and 

73,600,504 cubic feet. There is a 68-percent chance that the true number of trees 

(>1 inch diameter) on American Samoa lies within the range of 15,257,877 to 

20,551,881.

Resource Highlights

Forest Area

The islands of American Samoa are primarily forested (90.1 percent; fig. 4, table 2) 

as interpreted from IKONOS satellite imagery. Agroforest and coconut plantations 
10

RESOURCE BULLETIN PNW-RB-244

have replaced the majority of the native lowland rain forest (Mueller-Dombois and 

Fosberg 1998); however, we have included these managed lands in our definition of 

forested acreage. About 7.3 percent of the island group is classified as urban, occupying the gentle terrain where lowland rain forest previously existed. The important 

mangrove forests act as a buffer to storms and as a sediment and nutrient filter for 

water moving from the land to the ocean. Mangroves were recently mapped (American Samoa Community College) and are estimated to cover approximately 120 acres 

on American Samoa. The National Park Service leases approximately 16 percent of 

the land on American Samoa for the National Park of American Samoa.

Loss of Forest Land and Mangroves

The FIA group recently digitized the 1988 American Samoa land cover map (Cole 

et al. 1988) to compare with the recently produced IKONOS-based land cover map. 

We estimate that forest land area has declined by about 3 percent over the 15-year 

period (figs. 4 and 5, table 2). However, during this same period, the area occupied 

by mangroves has declined by approximately 18 percent as shown by the land cover 

Table 2—Estimated land area by land status, 1985 and 2001

1985 acres 2001 acres

 Ofu and Tutuila and Ofu and Tutuila and

Land status Ta’u Olosega Aunu’u Total Ta’u Olosega Aunu’u Total

Accessible forest land:

 Unreserved forest land 10,837 2,978 30,976 44,791 7,108 1,450 27,368 35,928

 Protected forest land (National 

 Park Service lease and reserves)a — — — — 3,711 1,509 2,362 7,581

 Mangroveb — — 148 148 — — 122 122

 All accessible forest land 10,837 2,978 31,124 44,939 10,819 2,959 29,852 43,631

Nonforest and other areas:

 Nonforest urban 116 33 2,252 2,401 125 36 3,368 3,530

 Nonforest vegetation 233 95 776 1,104 156 47 511 715

 Barren lands — — 14 14 131 74 343 548

 Water — — 64 64 — — 10 10

 All nonforest and other 349 128 3,106 3,583 412 157 4,232 4,803

Total area (acres) 11,186 3,106 34,230 48,522 11,231 3,116 34,084 48,434

Nonsampled area:

 Access denied — — — —

 Hazardous conditions 3,017 — 1,207 4,224

Notes: — = none. 

Land area figures for 2001 acreage differ slightly from published survey area owing to boundary edges being constrained to square pixels on our 

satellite-image-derived vegetation map. Land area figures for 1986 acreage are computed from Cole et al. (1988) USDA Forest Service vegetation maps 

that were scanned and digitized for a geographic information system by FIA in 2002.

a

 Estimates of protected forest land acreage are from Graves 2003.

b

 Unpublished data from global positioning system survey by American Samoa Forestry Division and American Samoa Community College.

Urban lands expanded 

from 5 percent of the 

total land area to 7 

percent in 15 years. 

Mangroves declined 

sharply in extent.
11

American Samoa’s Forest Resources, 2001

16%

7%

1% 0.24%

1%

74%

American Samoa’s Land Cover, 2001

Unreserved forest

National park

Urban

Nonforest vegetation

Barren

Mangrove

Figure 4—Land cover was mapped for American Samoa by using high-resolution satellite imagery. 

American Samoa is currently about 90 percent forested, including agroforest and plantations, and 

about 7 percent urban lands.

5%

0.31%

2%

93%

American Samoa’s Land Cover, 1986

Unreserved forest

National park (0%)

Urban

Nonforest vegetation

Barren (0.03%)

Mangrove

Figure 5—American Samoa was approximately 93 percent forested and 5 percent urban lands in 

1986.
12

RESOURCE BULLETIN PNW-RB-244

maps. Mangrove area has declined rapidly as increasing population and urbanization 

pressure has led to cutting and filling of mangroves (Whistler 1980). The 1988 map 

was produced via air photointerpretation aided by ground truthing, whereas the 2001 

estimates were derived from mapping mangrove boundaries with global positioning 

systems. A more thorough inventory of the mangrove areas is currently being conducted by the Division of Forestry on American Samoa. Urban lands have increased 

by an estimated 47 percent. In contrast, the establishment of the National Park of 

American Samoa has increased protected lands from none in 1986 to 16 percent in 

2001.

Productivity

Potential productivity on forest land is relatively high where there are sufficient 

plains, plateaus, and local depressions to hold precipitation for plant growth (fig. 

6). However, much of American Samoa is steeply sloped terrain (Nakamura 1984) 

where soil is retained primarily by vegetative cover (Mueller-Dombois and Fosberg 

1998). In the first forestry survey of American Samoa, Nelson (1964) reports, 

“...approximately half of the forested area is of such steep slope and thin soil that 

practical considerations and the need to protect watershed values should prohibit 

or limit forest utilization of disturbances.”

Forest Structure

Forest stands tend to be dominated by moderate-sized trees that primarily range 

from about 5 to 20 inches in diameter (fig. 7). The majority of forest acreage is 

classified as stands with trees that average 5 to 10.9 inches in diameter. No stands 

were classified as larger diameter (20+ inches) stands; however, there are occasional 

large trees within the matrix of moderate-sized trees.

Regeneration

Regeneration in American Samoa forests is plentiful. The diameter distribution for 

trees follows a reverse-J pattern, typical of all-aged forests (fig. 8, table 3). Through 

time, the numbers of trees growing into larger diameter size classes steadily decreases with increasing size class as competition and mortality take their toll. Hurricane, 

insects, disease, and human disturbance contribute to mortality as well.

Wood Volume

Tree stem volume on forest land in American Samoa averaged approximately 

1,530 cubic feet per acre. Reanalysis of the 1985 timberland data for American 

Samoa shows stem volume to have been approximately 1,700 cubic feet per acre 

at that time (Cole et al. 1988). However, the 1985 values do not include agroforest, 

The majority of forest 

acreage is dominated 

by trees averaging 5 to 

11 inches in diameter.
13

American Samoa’s Forest Resources, 2001

5%

2,349 7%

2,936

36%

15,516

12%

5,284

9%

4,110

31%

13,435

Forest Land Potential Productivity

(Percentage of total forest area and acreage)

Low (5–9.9)

Medium low (10–14.9)

Medium (15–19.9)

Medium high (20–24.9)

High (25–29.9)

Highest (30–40)

Figure 6—Based on a topographic relative moisture index (TRMI, i.e., moisture availability), much of the land on 

American Samoa is potentially medium to high productivity. Numbers in the legend represent scores on the TRMI.

587

19,378

15,545

0

8,221

25,000

20,000

15,000

10,000

5,000

0

Stand Size Class

Less than

5 inches

5–10.9

inches

11–19.9

inches

20+ inches

Area (acres)

Nonstocked

Figure 7—Although some large trees are present, stands are characterized primarily by small- to medium-diameter 

trees.
14

RESOURCE BULLETIN PNW-RB-244

0

1

2

3

4

5

6

Number of Trees by Size Class

Total trees in all classes: 17,904,879

1.0–2.9

3.0–4.9

5.0–6.9

7.0–8.9

9.0–10.9

11.0–12.9

13.0–14.9

15.0–16.9

17.0–18.9

19.0–20.9

21.0–22.9

23.0–24.9

25.0–26.9

27.0–28.9

29.0+

Diameter (inches)

Trees (millions)

Figure 8—Smaller trees are the most numerous across all size classes. The number of these trees that grow into 

larger size classes gradually diminishes through time, typical of all-aged forests.

steep forest, scrub, or moss forest, which would be expected to lower the overall 

average volume figure. Timberland is considered the most productive subset of forest land, where timberland is defined as being capable of producing at least 20 cubic 

feet of industrial wood per acre per year. A similar average volume on timberland

of 1,668 cubic feet per acre was found on Palau (MacLean et al. 1988), whereas 

a lower average forest land volume of 940 cubic feet per acre was estimated for 

Guam where small-diameter trees are predominant (Donnegan et al. 2004). Nelson 

(1964) estimated an average of about 8,000 board feet per acre on forest land in 

American Samoa. To roughly convert board foot volume to cubic foot volume, we 

divided by five, estimating about 1,600 cubic feet per acre at the time of Nelson’s 

(1964) survey. Although there are relatively few larger trees on American Samoa, 

their large diameters and heights contribute greatly to volume in the upper diameter 

size classes (fig. 9, tables 4 and 5).

Biomass and Carbon

Biomass and carbon distribution by diameter class closely follows the pattern seen 

in volume by diameter class (fig. 10, tables 6 and 7). Approximately 22 percent of 

the individual tree species that were recorded on the FIA plots had known specific 

gravities for biomass calculations. The remainder of the species were assigned a 

specific gravity based on the average of known species.

Regeneration appears 

plentiful in American 

Samoa forests.
15

Table 3—Estimated number of live trees on forest land by species and diameter class

Diameter class (inches)

Species 1.0–2.9 3.0–4.9 5.0–6.9 7.0–8.9 9.0–10.9 11.0–12.9 13.0–14.9 15.0–16.9 17.0–18.9 19.0–20.9 21.0–22.9 23.0–24.9 

Number of trees

Adenanthera pavonina

—

— 14,135 28,270

—

—

—

—

—

—

—

—

Aglaia samoensis

—

—

—

—

—

—

—

— 14,135 14,135

— 14,135

Alphitonia zizyphoides

— 176,078 70,676 70,676 42,406

—

—

—

—

—

—

—

Artocarpus altilis 176,078

— 56,541 42,406 28,270

—

—

—

—

—

—

—

Barringtonia samoensis 704,314

—

—

— 14,135 14,135 14,135 14,135

—

—

—

—

Bischofia javanica

—

— 14,135 14,135

— 28,270 28,270

—

—

—

—

—

Buchanania merrillii

—

— 28,270

—

—

—

—

—

— 14,135

—

—

Calophyllum neo-ebudicum

—

— 14,135 14,135

—

—

—

—

—

—

—

—

Cananga odorata

— 352,157 56,541 70,676 70,676 42,406 28,270 28,270

—

—

—

—

Canarium ovatum

—

—

—

—

—

—

— 14,135

—

—

—

—

Canarium vitiense

—

— 14,135 14,135 14,135

—

—

—

—

—

— 14,135

Cassia fistula

—

—

—

—

— 14,135

—

—

—

—

—

— 

Castilla elastica

—

— 42,406 28,270

—

—

—

—

—

—

—

—

Cocos nucifera

—

— 28,270 28,270 197,893 169,622 113,081 14,135

—

—

—

—

Cyathea lunulata 352,157 176,078 508,867 56,541

— 28,270 14,135

—

—

—

—

—

Cyathea spp.

—

— 28,270

— 28,270

—

—

—

—

—

—

—

Diospyros samoensis 352,157

—

—

—

— 14,135 14,135

—

—

—

—

—

Dysoxylum maota 176,078 176,078 98,946 84,811 98,946 56,541 14,135 14,135 14,135 28,270

— 14,135

Dysoxylum samoense 176,078

— 14,135

—

—

—

—

—

—

—

—

—

Elaeocarpus ulianus 352,157 352,157 141,352 84,811 28,270

— 14,135

—

—

— 14,135

—

Elattostachys falcata

— 176,078

—

—

—

—

—

—

—

—

—

—

Erythrina fusca

—

—

—

—

— 14,135

—

—

— 14,135

—

—

Erythrina variegata

—

— 14,135

—

—

—

—

—

—

—

—

—

Ficus obliqua

—

—

—

— 14,135

—

—

—

—

—

—

—

Ficus scabra

— 176,078

—

—

— 14,135

—

—

—

—

—

—

Flacourtia rukam

—

— 70,676 14,135

—

—

—

—

—

—

—

—

Garcinia myrtifolia

— 176,078

—

—

—

—

—

—

—

—

—

—

Hernandia nymphaeifolia

— 176,078 42,406 14,135 14,135 14,135

—

—

—

—

—

—

Hibiscus tiliaceus 528,235 880,392 621,948 282,704 113,081 14,135 14,135

—

—

—

—

—

Inocarpus fagifer

—

— 28,270 42,406 28,270

—

— 14,135

— 14,135

—

—

Kleinhovia hospita

— 176,078 28,270

—

— 28,270

—

—

—

—

—

—

Macaranga grayana 176,078

— 14,135

—

—

—

—

—

—

—

—

—

Macaranga harveyana

—

— 14,135 56,541 56,541

— 14,135

—

—

—

—

—

Mangifera indica

—

—

—

— 14,135

—

—

—

—

—

—

—

Morinda citrifolia 352,157 352,157 14,135

— 14,135

—

—

—

—

—

—

—

Myristica fatua 704,314 880,392 424,056 183,757 98,946 14,135

— 14,135

—

—

—

—

Neisosperma oppositifolia 352,157 352,157 14,135

—

—

—

—

—

—

—

—

—

Neonauclea forsteri

—

— 42,406

—

— 14,135 14,135

— 14,135

—

— 28,270

Omalanthus nutans

—

—

—

—

—

—

—

— 14,135

—

—

—

Pipturus argenteus 528,235

— 42,406

— 14,135

—

—

—

—

—

—

—

Pisonia grandis

—

— 14,135

—

—

—

—

—

—

—

—

—

Planchonella garberi

— 176,078

— 14,135

— 14,135 14,135

—

—

—

—

—

Planchonella torricellensis

—

—

—

— 14,135

—

— 14,135

—

—

—

—

Psychotria insularum 176,078 176,078

—

—

—

—

—

—

—

—

—

—

Rhizophora mangle 176,078 528,235 42,406

— 14,135

—

— 14,135 28,270 14,135

—

—

Rhus taitensis

— 176,078 70,676 84,811 70,676 70,676 70,676 14,135 28,270

—

— 14,135

Scaevola taccada 352,157

— 14,135

—

—

—

—

—

—

—

—

—

Sterculia fanaiho

—

—

— 14,135

—

—

—

—

—

—

—

—

Syzygium inophylloides

—

— 28,270 14,135

—

—

— 42,406

—

—

—

—

Syzygium samarangense

—

— 14,135

—

—

—

—

—

—

—

—

—

Syzygium samoense 176,078

—

—

—

—

—

—

—

—

—

—

—

 Total 5,810,589 5,634,510 2,685,685 1,258,032 989,463 565,407 367,515 197,893 113,081 98,946 14,135 84,811 
16

10

9

8

7

6

5

4

3

2

1

0

5.0–6.9

7.0–8.9

9.0–10.9

11.0–12.9

13.0–14.9

15.0–16.9

17.0–18.9

19.0–20.9

21.0–22.9

23.0–24.9

25.0–26.9

27.0–28.9

29.0+

Diameter (inches)

Gross volume (million cubic feet)

Volume by Size Class

Total volume, all classes: 66,699,430

Figure 9—Larger trees contribute greatly to total volume of stem wood in American Samoa.

180

160

140

120

100

80

60

40

20

0

5.0–6.9

7.0–8.9

9.0–10.9

11.0–12.9

13.0–14.9

15.0–16.9

17.0–18.9

19.0–20.9

21.0–22.9

23.0–24.9

25.0–26.9

27.0–28.9

29.0+

Diameter (inches)

Stem biomass (thousand tons)

Biomass by Size Class

Biomass total, all classes: 1,100,526

Figure 10—Stem biomass is concentrated in the smaller size classes for trees in American Samoa.
17

American Samoa’s Forest Resources, 2001

Table 4—Estimated volume of all live trees on forest land by diameter class

Diameter class (inches)

<5 5–10.9 11–19.9 20+ All sizes

Cubic feet

Gross volume 5,591,558 26,209,076 24,801,007 15,689,347 72,290,988

Net volume a 26,131,770 24,494,828 15,553,000 66,179,597

a

 Net volume was not calculated for trees less than 5 inches in diameter.

Numbers of Canopy and Understory Species

In addition to tree measurements, understory vegetation was identified and its 

cover was estimated when it occupied at least 3 percent of an FIA subplot. Specialinterest species that were considered important by local foresters were estimated 

for cover even though their cover may have been less than 3 percent. The species 

estimates represent a rough approximation of cover and species numbers for the 

most common plants only. Fifty tree species and 86 understory plant species were 

identified on 20 FIA plots (tables 1, 8 and 9). To place our species numbers in 

context, Whistler (1980) suggests there are over 320 angiosperm species, and the 

National Park Service lists over 470 native species of flowering plants and ferns for 

American Samoa (Craig 2002). On a per-plot basis (approximately one-sixth of an 

acre: summing four subplots of 24-foot radius each = 7,238 square feet), there are 

fairly high numbers of tree species per plot, with an average of about seven species 

per plot (fig. 11).

Tree Damage and Mortality

Approximately 17 percent of the trees measured had some form of visible damage 

(fig. 12, table 10). The primary damage types were evident as open wounds and 

conks (fungal growth on the trunk often indicates rot). Damaged shoots often result 

in lost apical dominance, meaning that a stem leader is damaged to the point that 

another branch assumes dominance as the primary stem.

The FIA field crews attempt to assign a causal agent to tree damages that can 

help local forest managers detect forest pest problems before they become widespread. Often, the cause of damage cannot be reliably identified and is assigned 

as unknown. However, by studying the surrounding area looking for patterns of 

branch breakage and blowdown or signs of human or insect activity, a causal agent 

can be assigned to a damage type. Weather, insects, and humans tend to be identified as important primary and secondary disturbance agents in American Samoa 

forests (figs. 13 and 14).

Seventeen percent of 

the trees measured 

in American Samoa 

exhibited visible 

damages.
18Table 5—Estimated gross volume of all live trees on forest land by species and diameter class

Diameter class (inches)

Species 5.0–6.9 7.0–8.9 9.0–10.9 11.0–12.9 13.0–14.9 15.0–16.9 17.0–18.9 19.0–20.9 21.0–22.9 23.0–24.9 25.0–26.

Cubic feet

Adenanthera pavonina 58,075 156,231 — — — — — — — — — 

Aglaia samoensis — — — — — — 382,320 579,399 — 590,542 — 

Alphitonia zizyphoides 269,184 497,981 336,685 — — — — — — — — Artocarpus altilis 160,877 231,808 277,599 — — — — — — — — 

Barringtonia samoensis — — 126,521 107,428 253,016 241,414 — — — — — Bischofia javanica 41,136 77,345 — 244,268 452,859 — — — — — — Buchanania merrillii 100,989 — — — — — — 546,323 — — — 

Calophyllum neo-ebudicum 39,239 99,529 — — — — — — — — — 

Cananga odorata 226,591 481,230 730,310 831,758 778,143 737,853 — — — — — Canarium ovatum — — — — — 311,981 — — — — — Canarium vitiense 56,022 77,751 175,608 — — — — — — 700,884 — Cassia fistula — — — 302,032 — — — — — — 651,05

Castilla elastica 118,081 150,240 — — — — — — — — — 

Cocos nucifera 85,950 274,842 2,265,070 2,980,564 1,956,314 246,546 — — — — — 

Cyathea lunulata 1,113,553 272,218 — 349,977 247,596 — — — — — — 

Cyathea spp. 54,095 — 150,315 — — — — — — — — Diospyros samoensis — — — 174,419 259,841 — — — — — — Dysoxylum maota 353,999 592,021 904,649 1,028,319 553,074 366,017 303,165 1,278,742 — 559,298 — 

Dysoxylum samoense 39,925 — — — — — — — — — — 

Elaeocarpus ulianus 683,874 630,544 208,009 — 151,643 — — — 438,977 — — Erythrina fusca — — — 178,448 — — — 477,220 — — — 

Erythrina variegata 48,538 — — — — — — — — — — Ficus obliqua — — 130,280 — — — — — — — — 

Ficus scabra — — — 180,070 — — — — — — — 

Flacourtia rukam 208,538 55,584 — — — — — — — — — 

Hernandia nymphaeifolia 193,242 162,856 198,914 188,745 — — — — — — — 

Hibiscus tiliaceus 2,012,009 1,475,800 894,873 170,544 221,035 — — — — — — Inocarpus fagifer 70,820 242,499 206,203 — — 370,467 — 393,419 — — — 

Kleinhovia hospita 96,898 — — 333,966 — — — — — — — 

Macaranga grayana 40,388 — — — — — — — — — — 

Macaranga harveyana 41,640 346,466 485,194 — 361,717 — — — — — — Mangifera indica — — 77,300 — — — — — — — — 

Morinda citrifolia 30,452 — 107,167 — — — — — — — — 

Myristica fatua 2,093,677 1,282,281 1,208,118 268,509 — 363,906 — — — — — 

Neisosperma oppositifolia 43,268 — — — — — — — — — — 

Neonauclea forsteri 109,858 — — 163,166 181,906 — 233,821 — — 1,503,431 — Omalanthus nutans — — — — — — 269,468 — — — — Pipturus argenteus 122,790 — 79,893 — — — — — — — — 

Pisonia grandis 28,838 — — — — — — — — — — 

Planchonella garberi — 60,441 — 121,898 230,857 — — — — — — 

Planchonella torricellensis — — 100,836 — — 374,818 — — — — — 

Rhizophora mangle 100,129 — 100,828 — — 243,453 815,212 444,070 — — — Rhus taitensis 213,293 542,143 594,714 877,199 1,458,700 350,428 572,444 — — 773,880 — 

Scaevola taccada 46,070 — — — — — — — — — — 

Sterculia fanaiho — 44,372 — — — — — — — — — Syzygium inophylloides 97,264 59,322 — — — 791,198 — — — — — Syzygium samarangense 37,186 — — — — — — — — — —  Total 9,036,486 7,813,504 9,359,086 8,501,312 7,106,700 4,398,080 2,576,430 3,719,173 438,977 4,128,035 651,05
19

Table 6—Estimated aboveground dry stem weight of all live trees on forest land by species and diameter class

Diameter class (inches)

Species 5.0–6.9 7.0–8.9 9.0–10.9 11.0–12.9 13.0–14.9 15.0–16.9 17.0–18.9 19.0–20.9 21.0–22.9 23.0–24.9 25.0–26

Tons

Adenanthera pavonina 906 2,438 — — — — — — — — — 

Aglaia samoensis — — — — — — 5,967 9,042 — 9,216 — 

Alphitonia zizphoides 4,201 7,772 5,254 — — — — — — — — Artocarpus altilis 2,511 3,618 4,332 — — — — — — — — Barringtonia samoensis — — 1,975 1,677 3,949 3,768 — — — — — 

Bischofia javanica 693 1,304 — 4,117 7,633 — — — — — — 

Buchanania merrillii 1,576 — — — — — — 8,526 — — — 

Calophyllum neo-ebudicum 612 1,553 — — — — — — — — — 

Cananga odorata 2,051 4,356 6,610 7,529 7,043 6,679 — — — — — 

Canarium ovatum — — — — — 4,869 — — — — — 

Canarium vitiense 944 1,310 2,960 — — — — — — 11,813 — 

Cassia fistula — — — 6,693 — — — — — — 14,42

Castilla elastica 1,843 2,345 — — — — — — — — — Cocos nucifera 1,341 4,289 35,350 46,516 30,531 3,848 — — — — — Cyathea lunulata 17,379 4,248 — 5,462 3,864 — — — — — — Cyathea spp. 844 — 2,346 — — — — — — — — Diospyros samoensis — — — 2,722 4,055 — — — — — — Dysoxylum maota 5,525 9,239 14,118 16,048 8,632 5,712 4,731 19,957 — 8,729 — Dysoxylum samoense 623 — — — — — — — — — — 

Elaeocarpus ulianus 10,673 9,841 3,246 — 2,367 — — — 6,851 — — 

Erythrina fusca — — — 1,392 — — — 3,724 — — — 

Erythrina variegata 758 — — — — — — — — — — 

Ficus obliqua — — 2,033 — — — — — — — — Ficus scabra — — — 2,810 — — — — — — — 

Flacourtia rukam 3,255 867 — — — — — — — — — Hernandia nymphaeifolia 3,016 2,542 3,104 2,946 — — — — — — — Hibiscus tiliaceus 35,797 26,257 15,921 3,034 3,933 — — — — — — Inocarpus fagifer 1,105 3,785 3,218 — — 5,782 — 6,140 — — — Kleinhovia hospita 1,089 — — 3,753 — — — — — — — 

Macaranga grayana 630 — — — — — — — — — — 

Macaranga harveyana 650 5,407 7,572 — 5,645 — — — — — — Mangifera indica — — 1,255 — — — — — — — — Morinda citrifolia 475 — 1,673 — — — — — — — — Myristica fatua 49,978 20,012 13,546 4,190 — 5,679 — — — — — 

Neisosperma oppositifolia 675 — — — — — — — — — — 

Neonauclea forsteri 1,714 — — 2,546 2,839 — 3,649 — — 23,463 — 

Omalanthus nutans — — — — — — 4,205 — — — — Pipturus argenteus 1,916 — 1,247 — — — — — — — — Pisonia grandis 450 — — — — — — — — — — 

Planchonella garberi — 943 — 1,902 3,603 — — — — — — 

Planchonella torricellensis — — 1,574 — — 5,850 — — — — — Rhizophora mangle 1,563 — 1,574 — — 3,799 12,723 6,930 — — — 

Rhus taitensis 3,329 8,461 9,281 13,690 22,765 5,469 8,934 — — 12,078 — 

Sterculia fanaiho — 692 — — — — — — — — — 

Syzygium inophylloides 1,518 926 — — — 12,348 — — — — — 

Syzygium samarangense 580 — — — — — — — — — — 

 Total 160,221 122,205 138,190 127,029 106,858 63,802 40,209 54,319 6,851 65,299 14,42
20Table 7—Estimated aboveground weight of carbon for stems of all live trees on forest land by species and diameter class

Diameter class (inches)

Species 5.0–6.9 7.0–8.9 9.0–10.9 11.0–12.9 13.0–14.9 15.0–16.9 17.0–18.9 19.0–20.9 21.0–22.9 23.0–24.9 25.0–26

Tons

Adenanthera pavonina 444 1,195 — — — — — — — — — 

Aglaia samoensis — — — — — — 2,924 4,431 — 4,516 — Alphitonia zizyphoides 2,058 3,808 2,575 — — — — — — — — Artocarpus altilis 1,230 1,773 2,123 — — — — — — — — Barringtonia samoensis — — 968 822 1,935 1,846 — — — — — 

Bischofia javanica 340 639 — 2,017 3,740 — — — — — — 

Buchanania merrillii 772 — — — — — — 4,178 — — — Calophyllum neo-ebudicum 300 761 — — — — — — — — — Cananga odorata 1,005 2,134 3,239 3,689 3,451 3,273 — — — — — Canarium ovatum — — — — — 2,386 — — — — — 

Canarium vitiense 463 642 1,450 — — — — — — 5,789 — 

Cassia fistula — — — 3,280 — — — — — — 7,07Castilla elastica 903 1,149 — — — — — — — — — Cocos nucifera 657 2,102 17,321 22,793 14,960 1,885 — — — — — Cyathea lunulata 8,516 2,082 — 2,676 1,893 — — — — — — Cyathea spp. 414 — 1,149 — — — — — — — — Diospyros samoensis — — — 1,334 1,987 — — — — — — 

Dysoxylum maota 2,707 4,527 6,918 7,864 4,229 2,799 2,318 9,779 — 4,277 — Dysoxylum samoense 305 — — — — — — — — — — 

Elaeocarpus ulianus 5,230 4,822 1,591 — 1,160 — — — 3,357 — — 

Erythrina fusca — — — 682 — — — 1,825 — — — 

Erythrina variegata 371 — — — — — — — — — — 

Ficus obliqua — — 996 — — — — — — — — 

Ficus scabra — — — 1,377 — — — — — — — Flacourtia rukam 1,595 425 — — — — — — — — — 

Hernandia nymphaeifolia 1,478 1,245 1,521 1,443 — — — — — — — Hibiscus tiliaceus 17,540 12,866 7,801 1,487 1,927 — — — — — — 

Inocarpus fagifer 542 1,854 1,577 — — 2,833 — 3,009 — — — 

Kleinhovia hospita 534 — — 1,839 — — — — — — — 

Macaranga grayana 309 — — — — — — — — — — Macaranga harveyana 318 2,649 3,710 — 2,766 — — — — — — Mangifera indica — — 615 — — — — — — — — Morinda citrifolia 233 — 820 — — — — — — — — Myristica fatua 24,489 9,806 6,638 2,053 — 2,783 — — — — — 

Neisosperma oppositifolia 331 — — — — — — — — — — Neonauclea forsteri 840 — — 1,248 1,391 — 1,788 — — 11,497 — Omalanthus nutans — — — — — — 2,061 — — — — 

Pipturus argenteus 939 — 611 — — — — — — — — 

Pisonia grandis 221 — — — — — — — — — — 

Planchonella garberi — 462 — 932 1,765 — — — — — — 

Planchonella torricellensis — — 771 — — 2,866 — — — — — 

Rhizophora mangle 766 — 771 — — 1,862 6,234 3,396 — — — Rhus taitensis 1,631 4,146 4,548 6,708 11,155 2,680 4,378 — — 5,918 — Sterculia fanaiho — 339 — — — — — — — — — Syzygium inophylloides 744 454 — — — 6,050 — — — — — Syzygium samarangense 284 — — — — — — — — — — 

 Total 78,508 59,881 67,713 62,244 52,361 31,263 19,702 26,616 3,357 31,997 7,07
21

American Samoa’s Forest Resources, 2001

Table 8—Average nontree understory cover on FIA field subplots by species

 Number of Standard

Scientific name Cover subplots deviation

Percent

Alocasia macrorrhizos (L.) Schott 1 4 0

Alpinia purpurata (Vieill.) K. Schum. 3.5 6 1.8

Alpinia samoensis Rein. 1 4 0

Alstonia reineckeana Lauterb. 60 1 —

Alyxia bracteolosa Rich. ex A. Gray 3.4 30 5

Alyxia spp. Banks ex R. Br. 2.3 4 0.5

Ananas comosus (L.) Merr. 3 1 —

Angiopteris evecta (J.R. Forst.) Hoffmann 2.8 24 1.9

Angiopteris spp. Hoffm. 2.8 5 1.8

Asplenium nidus L. 3 36 1.9

Brachiaria mutica (Forsk.) T.Q. Nguyen 30 1 —

Caesalpinia major (Medik.) Dandy & Exell 1.7 3 0.6

Calochlaena straminea (Labill.) M.D. Turner & R.D. White 18.3 3 12.6

Canavalia rosea (Sw.) DC. 4 1 —

Centotheca lappacea (L.) Desv. 2.9 16 5.9

Clidemia hirta (L.) D. Don. 2.4 29 2.3

Colubrina asiatica (L.) Brongn. 4 1 —

Commelina diffusa Burm. 1 1 —

Cordyline spp. Comm. ex Juss. 7 3 3.6

Cordyline fruticosa (L.) Chev. 5 42 8.4

Cyathea spp. Sm. 2 1 —

Cyathea lunulata (Forst. f.) Copel. 4 3 3.6

Cyclosorus interruptus (Wild.) H. Ito 6.5 38 7.5

Cyperus longus L. 1 1 —

Cyperus rotundus L. 7 1 —

Cyrtandra spp. J.R. & G. Forst. 1 2 0

Davallia solida (Forst. f.) Sw. 4 35 3.5

Davallia spp. Sm. 1.8 4 1

Derris malaccensis Prain 10.5 2 6.4

Derris trifoliata (Lour.) 11 3 16.5

Dioscorea alata L. 1 1 —

Dioscorea bulbifera L. 2.2 13 0.8

Diplazium proliferum (Lam.) Thouars 1 1 —

Epipremnum pinnatum (L.) Engl. 4.3 34 7.3

Epipremnum spp. Schott 2.3 12 1

Faradaya spp. F. Muell. 7 14 7.9

Faradaya amicorum (Seem.) Seem. 4 25 4.3

Faradaya powellii Seem. ex Powell 4.3 4 0.5

Freycinetia reineckii Warb. 5.1 25 5.4

Hedychium coronarium Koenig 1 1 —

Heliconia spp. L. 2.9 14 2.2

Hoya australis R. Br. 1 1 —

Hoya spp. R. Br. 2.5 2 2.1

Lomagramma spp. J. Sm. 65 2 7.1

Macropiper puberulum (Benth.) Benth. 1.8 5 0.4

Manihot esculenta Crantz 10.7 3 8.1

Mariscus javanicus Houtt. 17.9 9 32.5
22

RESOURCE BULLETIN PNW-RB-244

Table 8—Average nontree understory cover on FIA field subplots by species 

(continued)

 Number of Standard

Scientific name Cover subplots deviation

Percent

Merremia peltata (L.) Merr. 32.7 3 54

Mikania micrantha Kunth 6.9 21 9.8

Mimosa pudica L. 3 1 —

Miscanthus floridulus (Labill.) Warb. ex K. Schum. & Laut. 3 2 2.8

Mucuna gigantea (Willd.) DC. 1 1 —

Musa balbisiana Colla 2 2 0

Musa spp. L. 3 1 —

Musa x paradisiaca L. 2 1 —

Nephrolepis hirsutula (G. Forst.) C. Presl. 5.3 3 3.1

Oplismenus compositus (L.) Beauv. 13 4 10.3

Paspalum conjugatum Berg. 15.5 4 14.2

Paspalum spp. L. 5 1 —

Passiflora samoensis Exell 1 1 —

Phaleria acuminata (A. Gray) Gilg 1.5 2 0.7

Phymatosaurus scolopendria (L. Burm.) Pichi-Serm. 5.4 17 8.6

Phymatosaurus spp. Pichi-Serm. 2.5 2 2.1

Piper graeffei Warb. 2.3 30 1.2

Piper latifolium L. f. = macropiper 2 1 —

Piper methysticum G. Forst. 30 1 —

Polyscias samoensis (A. Gray.) Harms. 1 1 —

Polyscias spp. J.R. & G. Forst. 3 11 2

Portulaca samoensis v. Poelln. 4 1 —

Procris pedunculata (Forst.) Wedd. 1 1 —

Psychotria insularum A. Gray 2 4 0

Pteris ensiformis Burm. f. 2 1 —

Pyrrosia lanceolata (L.) Farw. 2.5 2 2.1

Pyrrosia spp. Mirbel 3 2 1.4

Rhynchospora corymbosa (L.) Britt. 2.5 2 2.1

Saccharum officinarum L. 1 1 —

Sida samoensis Rech. 45 1 —

Tacca leontopetaloides (L.) Kuntze 1.8 6 1

Unknown fern 5 2 0

Unknown orchid 2 2 1.4

Unknown vine 12.5 4 21.7

Vigna marina (Burm. f.) Merr. 9.6 5 17

Wollastonia biflora (L.) DC. 2 2 0

Note: Percentage cover of “1” indicates cover less than or equal to 1 percent. Cover estimates are averaged among subplots 

where each species was found. A total of 72 subplots were surveyed for vegetation cover. The number of subplots where 

a species was found and the standard deviation for cover estimates provide an idea of spatial variability for each species 

across the island group.
23

American Samoa’s Forest Resources, 2001

Table 9—Average understory tree cover and number of FIA subplots where a 

species occurs

Scientific name Cover Number of subplots

Percent

Adenanthera pavonina 1.25 4

Aglaia samoensis 2.07 15

Alphitonia zizyphoides 1.8 5

Alstonia pacifica (Seem.) A.C. Smith 3 1

Antidesma sphaerocarpum Muell. Arg. 1 1

Antirhea sp. Comm. ex Juss. 2 1

Artocarpus altilis 2.05 13

Artocarpus odoratissimus Blanco 2 4

Barringtonia samoensis 1.25 4

Bischofia javanica 2.17 12

Calophyllum inophyllum L. 2 1

Calophyllum neo-ebudicum 2.14 7

Cananga odorata 5.53 15

Canarium harveyi Seem. 2 1

Canarium vitiense 2 3

Carica papaya L. 1 1

Cerbera manghas L. 1 3

Cinnamomum verum J. Presl. 1 1

Citrus sinensis (L.) Osbeck 1 1

Cocos nucifera 9.27 15

Cyathea decurrens (Hook.) 2 4

Cyathea lunulata 4 2

Cyathea spp. 4 10

Diospyros samoensis 2.41 33

Dysoxylum maota 2.64 38

Dysoxylum samoense 1.75 4

Elaeocarpus ulianus 2.5 9

Elattostachys falcata 1.25 8

Erythrina fusca 1 1

Erythrina variegata 6 1

Ficus godeffroyi Warb. 1.8 20

Ficus scabra 2.61 9

Ficus tinctoria Forst. f. 1.6 5

Flacourtia rukam 1.56 18

Geniostoma rupestre J.R. & G. Forst. 2.67 3

Glochidion cuspidatum Pax 1 1

Glochidion ramiflorum Forst. f. 1 2

Harpullia arborea (Blanco) Radlk. 1 1

Hernandia moerenhoutiana Guill. 1 1

Hibiscus tiliaceus 8.65 17

Inocarpus fagifer 1.78 9

Kleinhovia hospita 1.5 2

Macaranga harveyana 4.38 8

Macaranga stipulosa Muell. Arg. 1 1

Mangifera indica 1 1

Micromelum minutum Wight & Arn. 1 1

Morinda citrifolia 2.53 30

Myristica fatua 6.06 47
24

RESOURCE BULLETIN PNW-RB-244

Table 9—Average understory tree cover and number of FIA subplots where a 

species occurs (continued)

Scientific name Cover Number of subplots

Percent

Myristica hypargyraea A. Gray 1 1

Neonauclea forsteri 1 1

Omalanthus acuminatus Muell. Arg. 2 4

Omalanthus nutans 2 1

Pandanus reineckii Warb. 6.75 4

Pipturus argenteus 12.2 5

Pisonia grandis 1 1

Planchonella garberi 1.33 3

Planchonella samoensis Reinecke ex H.J. Lam 3.67 15

Planchonella torricellensis syn. Pouteria torr. 2 3

Polyscias samoensis 2 4

Premna serratifolia L. 2 1

Psychotria insularum 2.94 31

Rhus taitensis 7.6 10

Scaevola taccada (Gaertn.) Roxb. 8 1

Sterculia fanaiho 1.7 9

Syzygium inophylloides 2.69 16

Syzygium samarangense 1.64 11

Tarenna sambucina (Forst. f.) Dur. 3 1

Terminalia catappa (L.) 1.33 3

Terminalia richii A. Gray 1.25 4

Theobroma cacao L. 1 2

Note: Percentage cover of “1” indicates cover less than or equal to 1 percent. A total of 72 subplots were surveyed 

for understory tree cover. Cover estimates are averaged among subplots where each species was found.

6

5

4

3

2

1

0

Number of species

N

u

m

b

er of plots

1–2 3–4 5–6 7–8 9–10 11–12 13–14

Tree Species on FIA Plots

Figure 11—The average number of tree species per sixth-acre field plot was 7.
25

American Samoa’s Forest Resources, 2001

40%

26%

10%

10%

6%

5%

2%

1%

Tree Damages

5.5 million no damage

1.2 million with damage

Open wounds

Conks

Damaged shoots

Cracks or seams

Lost apical dominance

Canker or gall

Broken branches

Resinosis

Figure 12—Tree damage types primarily occurred as open wounds or conks.

Very little evidence of mortality was encountered on our sample plots. Hibiscus tiliaceus was the only dead tree species that could be reliably identified on FIA 

plots. From these data we estimated that about 12 percent of this species was dead.

Epiphytes

Plants that physically grow on trees by using space and moisture that might otherwise be available for the growth of the host tree are considered epiphytes in the 

FIA inventory. Depending on the amount and weight of plants growing in the 

branching network of a host tree, breakage of tree limbs can occur. Epiphytes 

also provide benefits including habitat, food supplies, and cooling effects in 

tropical forests. Field crews rated each tree sampled in the inventory according 

to epiphyte loading. We estimate that most trees on American Samoa support 

few or no epiphytes (table 11).

Pilot Test Outcomes

The methods used for this inventory were adapted from the national FIA Program. 

Although consistency in measurement between regions is critically important, 

some adaptations were required to capture the differences found in these tropical 

forests. We have maintained the ability to compare this data set with data collected 

in other FIA regions and have standardized these methods for the inventory of the 
26

RESOURCE BULLETIN PNW-RB-244

Table 10—Number of trees by primary damage type and species for all trees >5 inches diameter at breast 

height (includes dead trees)

Scientific name

No

damage

Broken 

branches

Canker 

or gall Conks

Cracks 

or seams

Damaged 

shoots

Lost apical 

dominance

Open 

wounds Resinosis

All 

damages

Adenanthera pavonina 42,406 — — — — — — — — —

Aglaia samoensis 42,406 — — — — — — — — —

Alphitonia zizyphoides 183,757 — — — — — — — — —

Artocarpus altilis 113,081 — — — — — — 14,135 — 14,135

Barringtonia samoensis — — — 42,406 — — 14,135 — — 56,541

Bischofia javanica 84,811 — — — 14,135 — — — — 14,135

Buchanania merrillii 42,406 — — — — — — — — —

Calophyllum neo-ebudicum 14,135 — — — — — — 14,135 — 14,135

Cananga odorata 240,298 — — 28,270 14,135 14,135 — — — 56,541

Canarium ovatum 14,135 — — — — — — — — —

Canarium vitiense 56,541 — — — — — — — — —

Cassia fistula 42,406 — — — — — — — — —

Castilla elastica 70,676 — — — — — — — — —

Cocos nucifera 155,487 — — — 28,270 98,946 — 254,433 14,135 395,785

Cyathea lunulata 593,678 — — 14,135 — — — — — 14,135

Cyathea spp. 56,541 — — — — — — — — —

Diospyros samoensis 28,270 — — — — — — — — —

Dysoxylum maota 409,920 — — 14,135 — — — 28,270 — 42,406

Dysoxylum samoense 14,135 — — — — — — — — —

Elaeocarpus ulianus 296,839 — — — — — — — — —

Erythrina fusca 14,135 — — 14,135 — — — — — 14,135

Erythrina variegata 14,135 — — — — — — — — —

Ficus obliqua 14,135 — — — — — — — — —

Ficus scabra 14,135 — — — — — — — — —

Flacourtia rukam 84,811 — — — — — — — — —

Hernandia nymphaeifolia 84,811 — — — — — — — — —

Hibiscus tiliaceus 1,024,190 — 28,270 70,676 14,135 — 42,406 42,406 — 197,893

Inocarpus fagifer 127,217 — — — — — — — — —

Kleinhovia hospita 56,541 — — — — — — — — —

Macaranga grayana 14,135 — — — — — — — — —

Macaranga harveyana 84,811 — 28,270 — — — — 28,270 — 56,541

Mangifera indica 14,135 — — — — — — — — —

Morinda citrifolia — — — 14,135 14,135 — — — — 28,270

Myristica fatua 678,489 14,135 — — 14,135 — 14,135 14,135 — 56,541

Neisosperma oppositifolia — 14,135 — — — — — — — 14,135

Neonauclea forsteri 98,946 — — 14,135 — — — — — 14,135

Omalanthus nutans 14,135 — — — — — — — — —

Pipturus argenteus 42,406 — — — — — — 14,135 — 14,135

Pisonia grandis 14,135 — — — — — — — — —

Planchonella garberi 42,406 — — — — — — — — —

Planchonella torricellensis 28,270 — — — — — — — — —

Rhizophora mangle 42,406 — — 70,676 — — — — — 70,676

Rhus taitensis 395,785 — — — 14,135 — — 28,270 — 42,406

Scaevola taccada 14,135 — — — — — — — — —

Sterculia fanaiho 14,135 — — — — — — — — —

Syzygium inophylloides 56,541 — — 14,135 — — — 14,135 — 28,270

Syzygium samarangense — — — — — — — 14,135 — 14,135

 Total 5,490,908 28,270 56,541 296,839 113,081 113,081 70,676 466,461 14,135 1,159,085
27

American Samoa’s Forest Resources, 2001

Figure 13—One-third of the most significant damages on trees were caused by unknown damaging 

agents. Weather, insects, and humans were the primary known damaging agents.

Figure 14—Over half of the secondary damaging agents were unknown, followed by animal damage.

32%

15%

13%

8%

7%

25%

Primary Damage Agent

Unknown

Weather

Insect

Human

Disease

Animal

61%

15%

8%

8%

8%

Unknown

Animal

Weather

Vegetation

Disease

Secondary Damage Agent
28

RESOURCE BULLETIN PNW-RB-244

Epiphyte loadings

Scientific name None Low Moderate High All loadings

Adenanthera pavonina 14,135 14,135 14,135 — 42,406

Aglaia samoensis 28,270 14,135 — — 42,406

Alphitonia zizyphoides 56,541 275,025 28,270 — 359,836

Artocarpus altilis 289,160 — 14,135 — 303,295

Barringtonia samoensis 704,314 56,541 — — 760,855

Bischofia javanica — 28,270 70,676 — 98,946

Buchanania merrillii — 28,270 14,135 — 42,406

Calophyllum neo-ebudicum — 28,270 — — 28,270

Cananga odorata 451,103 141,352 56,541 — 648,996

Canarium ovatum — — 14,135 — 14,135

Canarium vitiense 14,135 — 42,406 — 56,541

Cassia fistula 14,135 14,135 14,135 — 42,406

Castilla elastica — 14,135 56,541 — 70,676

Cocos nucifera 409,920 98,946 42,406 — 551,272

Cyathea lunulata 1,008,832 289,160 14,135 — 1,312,127

Cyathea spp. — 42,406 14,135 — 56,541

Diospyros samoensis — 176,078 204,349 — 380,427

Dysoxylum maota 260,890 317,430 226,163 — 804,483

Dysoxylum samoense 14,135 176,078 — — 190,214

Elaeocarpus ulianus 42,406 845,666 98,946 14,135 1,001,153

Elattostachys falcata — 176,078 — — 176,078

Erythrina fusca 14,135 14,135 — — 28,270

Erythrina variegata 14,135 — — — 14,135

Ficus obliqua — — 14,135 — 14,135

Ficus scabra — 190,214 — — 190,214

Flacourtia rukam 28,270 56,541 — — 84,811

Garcinia myrtifolia — 176,078 — — 176,078

Hernandia nymphaeifolia 260,890 — — — 260,890

Hibiscus tiliaceus 740,263 1,389,259 487,053 14,135 2,630,710

Inocarpus fagifer 56,541 56,541 14,135 — 127,217

Kleinhovia hospita 204,349 28,270 — — 232,619

Macaranga grayana 176,078 14,135 — — 190,214

Macaranga harveyana 56,541 14,135 42,406 28,270 141,352

Mangifera indica — — 14,135 — 14,135

Morinda citrifolia 176,078 556,506 — — 732,584

Myristica fatua 556,506 1,395,715 339,244 28,270 2,319,736

Neisosperma oppositifolia — 718,449 — — 718,449

Neonauclea forsteri — 14,135 98,946 — 113,081

Omalanthus nutans — 14,135 — — 14,135

Pipturus argenteus — 176,078 408,698 — 584,776

Pisonia grandis — 14,135 — — 14,135

Planchonella garberi 42,406 176,078 — — 218,484

Planchonella torricellensis — — 28,270 — 28,270

Psychotria insularum 176,078 176,078 — — 352,157

Rhizophora mangle 746,719 42,406 28,270 — 817,395

Rhus taitensis 84,811 317,430 212,028 — 614,269

Scaevola taccada 14,135 352,157 — — 366,292

Sterculia fanaiho — 14,135 — — 14,135

Syzygium inophylloides — 70,676 14,135 — 84,811

Syzygium samarangense — 14,135 — — 14,135

Syzygium samoense 176,078 — — — 176,078

 Total 6,831,990 8,727,671 2,626,699 84,811 18,271,171

Table 11—Estimated number of trees on forest land by amount of epiphytes and 

species (includes dead trees)
29

American Samoa’s Forest Resources, 2001

Pacific Islands. Comparing our acreage and volume estimates with those from prior 

surveys and surveys in similar tropical forests, we are confident that these methods 

provide statistically reliable estimates. These same methods will be used across the 

Pacific Islands to establish our base measurement. Remeasurement will occur every 

10 years to provide data on status and change in Pacific Island forest resources.

In addition to providing results for change detection, the FIA inventory provided field training for local foresters. The ongoing inventory has been conducted 

on a different island group each year by a multinational crew that has included the 

American Samoa foresters trained during this pilot test.

Acknowledgments

The FIA work in the Pacific Islands is a cooperative effort between a number of 

groups and agencies. We especially thank USDA Forest Service, State and Private 

Forestry in the Pacific Southwest Region for their strong support. Thanks to the 

Pacific Islands Imagery Consortium partners for sharing costs on imagery and 

interpretation. Thanks to the American Samoa Community College for logistical 

support, to Tom Cole at the Institute for Pacific Islands Forestry for helpful comments on the manuscript and help with re-analysis of the 1985 data (tables 12 and 

13). Thanks to Art Whistler at University of Hawaii for species identification training, to Lisa Fischer at the Remote Sensing Lab in the Pacific Southwest Region for 

imagery interpretation and mapping support, and to Walter Grabowiecki, Falaniko 

Mika, Ritofu Lotovale, Kitiona Fa’atamala, Tony Maugalei, and Aitasi Samele for 

field assistance and logistical support. We also thank Dale Weyermann, John Chase, 

Chuck Veneklase, and Ron Wanek with PNW-FIA for geographic information systems, programming, and technical support.

Metric Equivalents

When you know: Multiply by: To find:

Inches 2.54 Centimeters

Feet .3048 Meters

Miles 1.609 Kilometers

Acres .405 Hectares

Square feet .0929 Square meters

Cubic feet .0283 Cubic meters

Tons 907 Kilograms

Tons per acre 2.24 Tonnes or megagrams per hectare

Cubic feet per acre .06997 Cubic meters per hectare

Trees per acre 2.471 Trees per hectare
30

RESOURCE BULLETIN PNW-RB-244

Table 12—Net timberland volume by tree 

component 1985 a

Tree component Net timberland volume

Cubic feet

Sawtimber: 

 Sawlog 13,827,495

 Upper stem 3,024,293

 Craftwood bolts 617,640

 Branch and crotch 1,876,714

 Tip 186,875

 Roughwood 1,864,356

 Sawtimber total 21,397,373

Poletimber: 

 Poletimber 8,742,474

 Tip 676,447

 Branch 1,078,631

 Poletimber total 10,497,552

Total volume 31,894,925

a

 Data recompiled from Cole et al. (1988) by using current 

methods.

Table 13—Net timberland volume by species, American Samoa, 1985 a

Species Common name Net volume

Cubic feet

Aglaia samoensis laga’ali 440,400

Alphitonia zizyphoides toi 195,993

Alstonia spp. — 235,690

Arytera spp. lau’lili’i 165,953

Barringtonia samoensis falaga 249,787

Bischofia javanica ’o’a 590,180

Calophyllum samoense tamanu 3,493,340

Canaga odorata moso’oi 146,573

Cerbera manghas leva 446,289

Cinnamomum spp. ochod 129,611

Cocos nucifiera niu 409,406

Colubrina asiatica (L.) Brongn. fisoa 235,441

Cordia subcordata tauanave 271,251

Cyathea spp. olioli 116,711

Diospyros samoensis ’au’auli 1,400,345

Dysoxylum huntii Merr. maota mea 706,540

Dysoxylum maota maota 742,893

Dysoxylum samoense mamala 316,362

Erythrina variegata gatae 142,945

Eugenia spp. — 201,584

Ficus spp. mati 129,598

Flacourtia rukam filimoto 1,006,583

Garuga floribunda Decne. — 81,713
31

American Samoa’s Forest Resources, 2001

Table 13—Net timberland volume by species, American Samoa, 1985 a 

(continued)

Species Common name Net volume

Cubic feet

Gironniera celtidifolia Gaudich. lau’nini’i 371,115

Glochidion ramiflorum mamase 333,752

Guettarda speciosa belau 146,966

Hibiscus tiliaceus fau 1,084,986

Inocarpus fagifer ifi 1,220,209

Kleinhovia hospita fu’afu’a 245,938

Litsea samoensis papaono 297,593

Mangifera indica mago 688,846

Myristica spp. ‘atone 4,951,721

Neonauclea forsteri afa 242,893

Pimelodeudron spp. — 208,887

Planchonella spp. mamalava 302,166

Planchonella torricellensis mamalava 1,830,792

Psychotria spp. matalafi 374,340

Rhus taitensis tavai 5,306,192

Syzygium inophylloides asi 769,298

Terminalia richii malili 1,582,771

Trichospermum richii (Gray) Seem. elsau 63,461

Unknown — 17,813

 Total 31,894,925

a

 Data recompiled from Cole et al. (1988) by using current methods.

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