# 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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# 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 Re

sources, 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 North

west 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) Pro

gram 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 For

est Inventory and Analysis Program (FIA) in cooperation with Pacific Island forest

ers 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 for

ested 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 ero

sion, 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 topo

graphically 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 larg

est 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 introduc

ing 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 

# A v e r a g e M a x i m u m a n d M i n i m u m T e m p e r a t u r e

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 DecPrecipitation (inches) 

# Pago Pago, American Samoa, 1966–2001Temperature (°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 vegeta

tion 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 in

ventory 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 com

mon 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 moluccen

sis (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

Sterculi a 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

a 

## Specific 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 in

vasive plants, to pathogens, to culturally or economically important species of vari

ous 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 character

istics, 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 separat

ing 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 classifica

tion 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 

# F o r e s t I n v e n t o r y a n d A n a l y s i s

P a c i f i c I s l a n d s P l o t D e s i g n

N Overall plot footprint ~1.5 acres

Distance between subplot centers: 120 feet

D i s t a n c e f r o m s u b p l o t c e n t e r t o m i c r o p l o t c e n t e r : 1 2 f e e t



# 1 2

4 3 P l o t

S u b p l o t M i c r o p l o t 6.8-foot-radius microplot: seedlings + saplings 

# K ey

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, occu

pying 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 (Ameri

can 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 Mangrove b 

## — — 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% 0.24% 1% 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 con

ducted 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 decreas

es 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)

Hi ghest (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 2 5, 0 0 0

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+ inchesArea (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 for

est 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.

# 15Table 3—Estimated number of live trees on forest land by species and diameter classDiameter class (inches)Species1.0–2.93.0–4.95.0–6.97.0–8.99.0–10.911.0–12.913.0–14.915.0–16.917.0–18.919.0–20.921.0–22.923.0–24.925.0–26.927.0–28.929.0+All classesNumber of treesAdenanthera pavonina——14,13528,270———————————42,406Aglaia samoensis————————14,13514,135—14,135———42,406Alphitonia zizyphoides—176,07870,67670,67642,406——————————359,836Artocarpus altilis176,078—56,54142,40628,270——————————303,295Barringtonia samoensis704,314———14,13514,13514,13514,135———————760,855Bischofia javanica——14,13514,135—28,27028,270——————14,135—98,946Buchanania merrillii——28,270——————14,135—————42,406Calophyllum neo-ebudicum——14,13514,135———————————28,270Cananga odorata—352,15756,54170,67670,67642,40628,27028,270———————648,996Canarium ovatum———————14,135———————14,135Canarium vitiense——14,13514,13514,135——————14,135———56,541Cassia fistula—————14,135——————14,13514,135—42,406Castilla elastica——42,40628,270———————————70,676Cocos nucifera——28,27028,270197,893169,622113,08114,135———————551,272Cyathea lunulata352,157176,078508,86756,541—28,27014,135————————1,136,048Cyatheaspp.——28,270—28,270——————————56,541Diospyros samoensis352,157————14,13514,135————————380,427Dysoxylum maota176,078176,07898,94684,81198,94656,54114,13514,13514,13528,270—14,135—14,13514,135804,483Dysoxylum samoense176,078—14,135————————————190,214Elaeocarpus ulianus352,157352,157141,35284,81128,270—14,135———14,135————987,018Elattostachys falcata—176,078—————————————176,078Erythrina fusca—————14,135———14,135—————28,270Erythrina variegata——14,135————————————14,135Ficus obliqua————14,135——————————14,135Ficus scabra—176,078———14,135—————————190,214Flacourtia rukam——70,67614,135———————————84,811Garcinia myrtifolia—176,078—————————————176,078Hernandia nymphaeifolia—176,07842,40614,13514,13514,135—————————260,890Hibiscus tiliaceus528,235880,392621,948282,704113,08114,13514,135————————2,454,631Inocarpus fagifer——28,27042,40628,270——14,135—14,135—————127,217Kleinhovia hospita—176,07828,270——28,270—————————232,619Macaranga grayana176,078—14,135————————————190,214Macaranga harveyana——14,13556,54156,541—14,135————————141,352Mangifera indica————14,135——————————14,135Morinda citrifolia352,157352,15714,135—14,135——————————732,584Myristica fatua704,314880,392424,056183,75798,94614,135—14,135———————2,319,736Neisosperma oppositifolia352,157352,15714,135————————————718,449Neonauclea forsteri——42,406——14,13514,135—14,135——28,270———113,081Omalanthus nutans————————14,135——————14,135Pipturus argenteus528,235—42,406—14,135——————————584,776Pisonia grandis——14,135————————————14,135Planchonella garberi—176,078—14,135—14,13514,135————————218,484Planchonella torricellensis————14,135——14,135———————28,270Psychotria insularum176,078176,078—————————————352,157Rhizophora mangle176,078528,23542,406—14,135——14,13528,27014,135—————817,395Rhus taitensis—176,07870,67684,81170,67670,67670,67614,13528,270——14,135——14,135614,269Scaevola taccada352,157—14,135————————————366,292Sterculia fanaiho———14,135———————————14,135Syzygium inophylloides——28,27014,135———42,406———————84,811Syzygium samarangense——14,135————————————14,135Syzygium samoense176,078——————————————176,078Total5,810,5895,634,5102,685,6851,258,032989,463565,407367,515197,893113,08198,94614,13584,81114,13542,40628,27017,904,879

# 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 wide

spread. 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 identi

fied 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 classDiameter class (inches)Species5.0–6.97.0–8.99.0–10.911.0–12.913.0–14.915.0–16.917.0–18.919.0–20.921.0–22.923.0–24.925.0–26.927.0–28.929.0+All classesCubic feetAdenanthera pavonina58,075156,231———————————214,306Aglaia samoensis——————382,320579,399—590,542———1,552,261Alphitonia zizyphoides269,184497,981336,685——————————1,103,850Artocarpus altilis160,877231,808277,599——————————670,283Barringtonia samoensis——126,521107,428253,016241,414———————728,379Bischofia javanica41,13677,345—244,268452,859——————1,636,210—2,451,817Buchanania merrillii100,989——————546,323—————647,312Calophyllum neo-ebudicum39,23999,529———————————138,768Cananga odorata226,591481,230730,310831,758778,143737,853———————3,785,886Canarium ovatum—————311,981———————311,981Canarium vitiense56,02277,751175,608——————700,884———1,010,265Cassia fistula———302,032——————651,0551,217,466—2,170,552Castilla elastica118,081150,240———————————268,320Cocos nucifera85,950274,8422,265,0702,980,5641,956,314246,546———————7,809,286Cyathea lunulata1,113,553272,218—349,977247,596————————1,983,343Cyatheaspp.54,095—150,315——————————204,410Diospyros samoensis———174,419259,841————————434,261Dysoxylum maota353,999592,021904,6491,028,319553,074366,017303,1651,278,742—559,298—1,713,8422,467,57610,120,702Dysoxylum samoense39,925————————————39,925Elaeocarpus ulianus683,874630,544208,009—151,643———438,977————2,113,047Erythrina fusca———178,448———477,220—————655,668Erythrina variegata48,538————————————48,538Ficus obliqua——130,280——————————130,280Ficus scabra———180,070—————————180,070Flacourtia rukam208,53855,584———————————264,123Hernandia nymphaeifolia193,242162,856198,914188,745—————————743,757Hibiscus tiliaceus2,012,0091,475,800894,873170,544221,035————————4,774,262Inocarpus fagifer70,820242,499206,203——370,467—393,419—————1,283,409Kleinhovia hospita96,898——333,966—————————430,864Macaranga grayana40,388————————————40,388Macaranga harveyana41,640346,466485,194—361,717————————1,235,017Mangifera indica——77,300——————————77,300Morinda citrifolia30,452—107,167——————————137,619Myristica fatua2,093,6771,282,2811,208,118268,509—363,906———————5,216,492Neisosperma oppositifolia43,268————————————43,268Neonauclea forsteri109,858——163,166181,906—233,821——1,503,431———2,192,181Omalanthus nutans——————269,468——————269,468Pipturus argenteus122,790—79,893——————————202,683Pisonia grandis28,838————————————28,838Planchonella garberi—60,441—121,898230,857————————413,197Planchonella torricellensis——100,836——374,818———————475,654Rhizophora mangle100,129—100,828——243,453815,212444,070—————1,703,692Rhus taitensis213,293542,143594,714877,1991,458,700350,428572,444——773,880——1,935,4987,318,298Scaevola taccada46,070————————————46,070Sterculia fanaiho—44,372———————————44,372Syzygium inophylloides97,26459,322———791,198———————947,784Syzygium samarangense37,186————————————37,186Total9,036,4867,813,5049,359,0868,501,3127,106,7004,398,0802,576,4303,719,173438,9774,128,035651,0554,567,5184,403,07366,699,430

# 19Table 6—Estimated aboveground dry stem weight of all live trees on forest land by species and diameter classDiameter class (inches)Species5.0–6.97.0–8.99.0–10.911.0–12.913.0–14.915.0–16.917.0–18.919.0–20.921.0–22.923.0–24.925.0–26.927.0–28.929.0+All classesTonsAdenanthera pavonina9062,438———————————3,345Aglaia samoensis——————5,9679,042—9,216———24,225Alphitonia zizphoides4,2017,7725,254——————————17,227Artocarpus altilis2,5113,6184,332——————————10,461Barringtonia samoensis——1,9751,6773,9493,768———————11,367Bischofia javanica6931,304—4,1177,633——————27,578—41,325Buchanania merrillii1,576——————8,526—————10,102Calophyllum neo-ebudicum6121,553———————————2,166Cananga odorata2,0514,3566,6107,5297,0436,679———————35,232Canarium ovatum—————4,869———————4,869Canarium vitiense9441,3102,960——————11,813———17,028Cassia fistula———6,693——————14,42826,981—48,103Castilla elastica1,8432,345———————————4,188Cocos nucifera1,3414,28935,35046,51630,5313,848———————121,876Cyathea lunulata17,3794,248—5,4623,864————————30,953Cyatheaspp.844—2,346——————————3,190Diospyros samoensis———2,7224,055————————6,777Dysoxylum maota5,5259,23914,11816,0488,6325,7124,73119,957—8,729—26,74738,510162,229Dysoxylum samoense623————————————623Elaeocarpus ulianus10,6739,8413,246—2,367———6,851————32,977Erythrina fusca———1,392———3,724—————5,116Erythrina variegata758————————————758Ficus obliqua——2,033——————————2,033Ficus scabra———2,810—————————2,810Flacourtia rukam3,255867———————————4,122Hernandia nymphaeifolia3,0162,5423,1042,946—————————13,658Hibiscus tiliaceus35,79726,25715,9213,0343,933————————102,452Inocarpus fagifer1,1053,7853,218——5,782—6,140—————20,030Kleinhovia hospita1,089——3,753—————————6,743Macaranga grayana630————————————630Macaranga harveyana6505,4077,572—5,645————————19,274Mangifera indica——1,255——————————1,255Morinda citrifolia475—1,673——————————2,148Myristica fatua49,97820,01213,5464,190—5,679———————105,434Neisosperma oppositifolia675————————————675Neonauclea forsteri1,714——2,5462,839—3,649——23,463———34,212Omalanthus nutans——————4,205——————4,205Pipturus argenteus1,916—1,247——————————3,163Pisonia grandis450————————————450Planchonella garberi—943—1,9023,603————————8,626Planchonella torricellensis——1,574——5,850———————7,423Rhizophora mangle1,563—1,574——3,79912,7236,930—————33,059Rhus taitensis3,3298,4619,28113,69022,7655,4698,934——12,078——30,206114,213Sterculia fanaiho—692———————————692Syzygium inophylloides1,518926———12,348———————14,792Syzygium samarangense580————————————580Total160,221122,205138,190127,029106,85863,80240,20954,3196,85165,29914,42881,30668,7171,100,526

# 20Table 7—Estimated aboveground weight of carbon for stems of all live trees on forest land by species and diameter classDiameter class (inches)Species5.0–6.97.0–8.99.0–10.911.0–12.913.0–14.915.0–16.917.0–18.919.0–20.921.0–22.923.0–24.925.0–26.927.0–28.929.0+All classesTonsAdenanthera pavonina4441,195———————————1,639Aglaia samoensis——————2,9244,431—4,516———11,870Alphitonia zizyphoides2,0583,8082,575——————————8,441Artocarpus altilis1,2301,7732,123——————————5,126Barringtonia samoensis——9688221,9351,846———————5,570Bischofia javanica340639—2,0173,740——————13,513—20,249Buchanania merrillii772——————4,178—————4,950Calophyllum neo-ebudicum300761———————————1,061Cananga odorata1,0052,1343,2393,6893,4513,273———————17,263Canarium ovatum—————2,386———————2,386Canarium vitiense4636421,450——————5,789———8,344Cassia fistula———3,280——————7,07013,221—23,570Castilla elastica9031,149———————————2,052Cocos nucifera6572,10217,32122,79314,9601,885———————59,719Cyathea lunulata8,5162,082—2,6761,893————————15,167Cyatheaspp.414—1,149——————————1,563Diospyros samoensis———1,3341,987————————3,321Dysoxylum maota2,7074,5276,9187,8644,2292,7992,3189,779—4,277—13,10618,87079,492Dysoxylum samoense305————————————305Elaeocarpus ulianus5,2304,8221,591—1,160———3,357————16,159Erythrina fusca———682———1,825—————2,507Erythrina variegata371————————————371Ficus obliqua——996——————————996Ficus scabra———1,377—————————1,377Flacourtia rukam1,595425———————————2,020Hernandia nymphaeifolia1,4781,2451,5211,443—————————6,693Hibiscus tiliaceus17,54012,8667,8011,4871,927————————50,201Inocarpus fagifer5421,8541,577——2,833—3,009—————9,814Kleinhovia hospita534——1,839—————————3,304Macaranga grayana309————————————309Macaranga harveyana3182,6493,710—2,766————————9,444Mangifera indica——615——————————615Morinda citrifolia233—820——————————1,052Myristica fatua24,4899,8066,6382,053—2,783———————51,663Neisosperma oppositifolia331————————————331Neonauclea forsteri840——1,2481,391—1,788——11,497———16,764Omalanthus nutans——————2,061——————2,061Pipturus argenteus939—611——————————1,550Pisonia grandis221————————————221Planchonella garberi—462—9321,765————————4,227Planchonella torricellensis——771——2,866———————3,637Rhizophora mangle766—771——1,8626,2343,396—————16,199Rhus taitensis1,6314,1464,5486,70811,1552,6804,378——5,918——14,80155,964Sterculia fanaiho—339———————————339Syzygium inophylloides744454———6,050———————7,248Syzygium samarangense284————————————284Total78,50859,88167,71362,24452,36131,26319,70226,6163,35731,9977,07039,84033,671539,257

# 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 — Angiopte ris 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 speciesNumberofplots



## 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

Ope n wounds

Conks

Damaged shoots

Cracks or seams

Lost apical dominance

Canker or gall

Broken branches

Resinos is

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



# Very little evidence of mortality was encountered on our sample plots. Hibis

cus 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 pro

vided 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 com

ments 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 train

ing, 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 sys

tems, programming, and technical support.



# Metric Equivalents

When you know: Multiply by: To find:

Inc hes 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 meter s 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.



# Literature Cited

Cochran, W.G. 1977. Sampling techniques. New York: John Wiley and Sons.

428 p.

Cole, T.G.; Whitesell, C.D.; Whistler, W.A.; McKay, N.; Ambacher, A.H. 1988.

Vegetation survey and forest inventory, American Samoa. Resour. Bull. PSWRB-25. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station. 14 p.

Craig, P., ed. 2002. Natural history guide to American Samoa. Pago Pago,

American Samoa: U.S. Department of the Interior, National Park of American

Samoa, Department of Marine and Wildlife Resources. 76 p.

Donnegan, J.A.; Butler, S.L.; Graboweicki, W.; Hiserote, B.A.; Limtiaco, D.

2004. Guam’s forest resources, 2002. Resour. Bull. PNW-RB-243. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research

Station.

# 32 RESOURCE BULLETIN PNW-RB-244



# Graves, A. 2003. Land type delineation, Ta’u, Ofu, Olosega and Tutuila Islands,

National Park of American Samoa. National Park Service and American Samoa

Users Group, Pago Pago, American Samoa. http://doc.asg.as. (March 2004).

MacLean, C.D.; Cole, T.G.; Whitesell, C.D.; McDuffie, K.E. 1988. Timber

resources of Babelthuap, Republic of Palau. Resour. Bull. PSW-RB-23. Albany,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest

and Range Experiment Station. 8 p.

Mueller-Dombois, D.; Fosberg, F.R. 1998. Vegetation of the tropical Pacific

Islands. New York: Springer-Verlag. 733 p.

Nakamura, S. 1984. Soil survey of American Samoa. Washington, DC: U.S.

Department of Agriculture, Soil Conservation Service. 95 p.

Nelson, R.E. 1964. A look at the forests of American Samoa. Res. Note PSWRN-53. Honolulu, HI: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station. 8 p. + plates and maps.

Parker, A.J. 1982. The topographic relative moisture index: an approach to soilmoisture assessment in mountain terrain. Physical Geography. 3: 160–168.

U.S. Department of Agriculture, Forest Service. 2002. Field instructions for

the inventory of the Pacific Islands. Portland, OR: Pacific Northwest Research

Station, Forest Inventory and Analysis. 256 p.

U.S. Department of Agriculture, Forest Service. 2003. Forest inventory and

analysis national core field guide, volume 1: field data collection procedures

for phase 2 plots, version 1.7. Internal report. On file with: U.S. Department

of Agriculture, Forest Service, Forest Inventory and Analysis, 201 14th St.,

Washington, DC 20250.

Whistler, W.A. 1980. The vegetation of Eastern Samoa. Allertonia. 2: 45–190.

Whistler, W.A. 1992. Vegetation of Samoa and Tonga. Pacific Science.

46: 159–178.

# Pacific Northwest Research Station

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Telephone (503) 808-2592

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P.O. Box 3890 Portland, OR 97208-3890

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