Natural Resources
Conservation Service

Ecological site QX197X01X504

Alluvial Valley Forest

Last updated: 8/21/2026
Accessed: 10/16/2026

Home / esd CATALOG / MLRA 197X / ecological site QX197X01X504

USC

Metric

General information

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

MLRA notes

Major Land Resource Area (MLRA): 197X–Volcanic Islands of American Samoa

This MLRA consists of the islands of Tutuila, Aunuu, Ofu, Olosega, and Tau. The islands have extremely steep, highly dissected mountains, small valleys, and a narrow coastal plain. More than half of the area has slopes of more than 70 percent. The highest elevations are 3,056 feet (931 meters) on Tau and 2,142 feet (653 meters) on Tutuila. The islands consist of Pleistocene-age, basic igneous rocks, mainly basalt with some andesite and trachyte (USDA-NRCS, 2006).

The climate is moist, warm, and humid. Average annual rainfall ranges from 125 inches (3,175 millimeters) to more than 250 inches (6,350 millimeters). Rainfall varies over short distances due to topography. The driest months are June through September; the wettest months are December through March. Average annual temperature is 81 degrees F (27 degrees C). Relative humidity is 73 to 90 percent throughout the year. Prevailing winds are easterly trade winds. Cyclones occasionally strike the area (USDA-NRCS, 2006).

Soils are Mollisols, Andisols, Entisols, Oxisols, and Histosols. Soil moisture regimes are udic or perudic; the soil temperature regime is isohyperthermic. Natural vegetation is mostly tropical hardwood forest (USDA-NRCS, 2006).

Classification relationships

This ecological site occurs within Major Land Resource Area (MLRA) 197 – Volcanic Islands of American Samoa.

Ecological site concept

This ecological site occurs on the island of Tutuila in American Samoa. It occurs on nearly level to gently sloping (0 to 6 percent) valley floors at elevations ranging from 0 to 660 feet (0 to 200 meters) elevation. It is accessible on the southern side of Tutuila (Green et al., 2015; USDA-SCS, 1984).

Soils are Cumulic Hapludolls (Mollisols soil order). They formed in alluvium deposited over basic igneous rock. Soil temperature regimes are isohyperthermic; soil moisture regimes are udic. Average annual rainfall ranges from 150 to 250 inches (3,810 to 6,350 millimeters). Water runoff is slow. Effective rooting depths are more than 60 inches (150 centimeters). The soils in this ecological site are somewhat poorly drained and undergo occasional, brief flooding (USDA-SCS, 1984).

This forest type has a stratified canopy. The upper canopy grows up to 100 feet (30 meters) tall. Ground cover is moderate to dense; epiphytes and lianas are common (USDA-SCS, 1984; Whistler, 2002).

Associated sites

QX197X01X501	Mangrove Swamp Mangrove Swamp Ecological Site adjoins Alluvial Valley Forest Ecological Site where valley floors and coastal plains descend to partially-protected coastal salt water. Mangrove Swamp Ecological Site differs from Alluvial Valley Forest Ecological Site in being very poorly drained rather than somewhat poorly drained, having salt water rather than fresh water, and by undergoing twice-daily tidal flooding rather than occasional, brief flooding.
QX197X01X503	Lavaflow Forest Lavaflow Forest Ecological Site adjoins Alluvial Valley Forest Ecological Site in the few locations where alluvial valleys descend to young aa lava flows near the coast. Alluvial Valley Forest Ecological Site has somewhat poorly drained, mineral soils; Lavaflow Forest Ecological Site has well drained, organic soils in the interstices between aa rocks.
QX197X01X507	Dry Coastal Forest Dry Coastal Forest Ecological Site adjoins Alluvial Valley Forest Ecological Site where sloping uplands, side slopes, and mountain slopes descend to alluvium-filled valleys near the coast. Dry Coastal Forest Ecological Site has well drained Andisols with limited rooting depth formed from volcanic ash deposited over hard tuff, or, in one case, in the interstices between aa rocks. Alluvial Valley Forest Ecological Site has somewhat poorly drained Cumulic Mollisols with very deep rooting depth and formed in alluvium.
QX197X01X505	Skeletal Pachic or Fulvic Forest Skeletal Pachic or Fulvic Forest Ecological Site adjoins Alluvial Valley Forest Ecological Site where uplands, talus slopes, and mountain slopes descend to alluvium-filled valleys near the coast. It occurs on mountain slopes up to 1,000 feet in elevation, undergoes no flooding, and has well drained soils, in contrast with Alluvial Valley Forest Ecological Site, which ascends to 660 feet elevation, undergoes occasional brief flooding, and has somewhat poorly drained soils.
QX197X01X509	Very Steep Forest Very Steep Forest Ecological Site adjoins Alluvial Valley Forest Ecological Site where very steep mountain slopes descend to alluvium-filled valleys near the coast. It occurs on slopes up to 1,180 feet in elevation, undergoes no flooding, and has well drained soils, in contrast with Alluvial Valley Forest Ecological Site, which ascends to 660 feet elevation, undergoes occasional brief flooding, and has somewhat poorly drained soils.

Table 1. Dominant plant species

Tree	(1) Dysoxylum (2) Myristica
Shrub	Not specified
Herbaceous	(1) Lomagramma cordipinna

Legacy ID

F197XY504AS

Download full description

Physiographic features

This ecological site occurs on valley floors (USDA-SCS, 1984).

Table 2. Representative physiographic features

Landforms	(1) Island > Valley floor
Runoff class	Very low
Flooding frequency	None to occasional
Ponding frequency	None
Elevation	0 – 660 ft
Slope	0 – 6 %
Water table depth	36 – 60 in
Aspect	Aspect is not a significant factor

Climatic features

The area is characterized by abundant rain and warm, humid days and nights. Average annual precipitation in this ecological site ranges from 150 to 250 inches (3,810 to 6,350 millimeters). Mean annual air temperature is 79 to 80 degrees F (27 degrees C). The driest period is June through September (winter), and the wettest is December through March (summer), although heavy showers and long, rainy periods can occur in any month. June, July, and August are the coolest months, and January, February, and March are the warmest. Daytime temperatures typically reach the upper 80 degrees F in summer and the middle 80 degrees F in winter, while nighttime temperatures are in the middle 70 degrees in summer and low 70 degrees in winter.

The prevailing winds throughout the year are the easterly trade winds. They tend to be more directly from the east in December through March and mostly from the east-southeast and southeast during the rest of the year. The trade winds are less prevalent in summer than in winter. About 25 to 30 thunderstorms occur in an average year, mainly during the rainy season. The area lies across the path of tropical disturbances, including cyclones, that come usually from the north, but occasionally from east or west (USDA-SCS, 1984; USDI-FWS, 1982).

Table 3 Representative climatic features

Frost-free period (characteristic range)	370 days
Freeze-free period (characteristic range)	370 days
Precipitation total (characteristic range)	150-250 in
Frost-free period (actual range)	370 days
Freeze-free period (actual range)	370 days
Precipitation total (actual range)	150-250 in
Frost-free period (average)	370 days
Freeze-free period (average)	370 days
Precipitation total (average)	200 in

Characteristic range

Actual range

Bar

Line

Figure 1. Monthly precipitation range

Characteristic range

Actual range

Bar

Line

Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

Bar

Line

Figure 3. Monthly maximum temperature range

Bar

Line

Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6 Annual average temperature pattern

Climate stations used

(1) PAGO PAGO WSO AP [AQW00061705], AS

Soil features

Soils are Cumulic Hapludolls (Mollisols soil order). “Cumulic” means they have a thick mollic epipedon that developed by accumulation of surface material as the soils developed. They formed in alluvium deposited over basic igneous rock. Soil temperature regimes are isohyperthermic; soil moisture regimes are udic. They are very deep and somewhat poorly drained (USDA-SCS, 1984). Leafu is the soil component correlated to this ecological site.

Table 4. Representative soil features

Parent material	(1) Alluvium
Surface texture	(1) Stony silty clay (2) Silty clay
Family particle size	(1) Fine
Drainage class	Somewhat poorly drained
Permeability class	Moderate
Depth to restrictive layer	72 in
Soil depth	72 in
Surface fragment cover <=3"	0 – 2 %
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	4.6 – 6.1 in
Calcium carbonate equivalent (0-40in)	Not specified
Electrical conductivity (0-40in)	Not specified
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-40in)	5.6 – 6.5
Subsurface fragment volume <=3" (0-40in)	11 – 14 %
Subsurface fragment volume >3" (0-40in)	2 – 4 %

Ecological dynamics

The main natural disturbance is strong storms that can damage or kill vegetation by high wind speeds. The main human disturbance is clearing of native vegetation for agriculture and abandonment of plantations that results in at least temporary dominance of introduced weedy plants (Forestry Program, Division of Community and Natural Resources, 2010; Sene, 2020; Webb and Fa`aumu, 1999; Whistler, 2002).

State and transition model

Custom diagram

Standard diagram

Figure 7. State and Transition Model (STM) Alluvial Valley Forest

More interactive model formats are also available. View Interactive Models

More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Reference State

2. Naturalized Grassland

3. Cleared and Abandoned

4. Invaded Forest State

T1A	-	Removal of native vegetation and planting, or colonization of, introduced grass species.
T1B	-	Cleared of forest and then abandoned.
T1C	-	Wind damage or grazing to the native species.
R2A	-	Suppression of grassland vegetation and replanting with native species.
T2B	-	Abandonment of grasslands.
R3B	-	Active restoration of native species and suppression of non-native species.
R3A	-	Land clearing, weed control, and replanting grasses.
T3A	-	Growth of an overstory of non-native plants including trees, an understory of shade-tolerant shrubs, vines, ferns, forbs, and grasses.
R4A	-	Active restoration of native species and suppression of non-native species.
R4B	-	Removal of present vegetation and subsequent abandonment.

State 1 submodel, plant communities

1.1. Mamala - Atone/Lomagramma

1.2. Tavai – Maota/Lomagramma

1.1A	-	Storms or fires that damage or kill trees.
1.2A	-	Adequate time to recover after disturbance.

State 2 submodel, plant communities

2.1. Californiagrass/Spanish clover

2.2. Comb Bushmint – Nettleleaf Velvetberry/Californiagrass – Hilograss/Climbing Dayflower

2.1A	-	Excessive grazing.
2.2A	-	Reducing grazing pressure on Californiagrass and weed control.

State 3 submodel, plant communities

3.1. Lantana – Honolulu Rose/Fua Lele/Mile-A-Minute Vine/Californiagrass

State 4 submodel, plant communities

4.1. Mamala – African tuliptree/Koster’s Curse/ Mile-A-Minute Vine/Running Mountaingrass

State 1
Reference State

This ecological site is forested with a very tall (80 to 100 feet or 25 to 30 meters), stratified tree canopy. Ground cover is moderately dense to dense. Epiphytes and lianas are common (Forestry Program, Division of Community and Natural Resources, 2010; Sene, 2020; Webb and Fa`aumu, 1999; Whistler, 2002).

Dominant plant species

(Dysoxylum), tree
nutmeg (Myristica), tree
(Rhus taitensis), tree
(Lomagramma cordipinna), other herbaceous

Community 1.1
Mamala - Atone/Lomagramma

Dominant tree species are mamala (Homalanthus nutans), maota (Dysoxylum maota), fuafua (Kleinhovia hospita), atone (Myristica inutilis), mamalava (Planchonella samoensis), ifi (Inocarpus fagifer), auauli (Diospyros samoensis), fanaio (Sterculia fanaiho), and mati vao (Ficus scabra). The subcanopy usually consists of auauli (Diospyros samoensis), atone (Myristica inutilis), falaga (Barringtonia samoensis), or a combination of all three (Forestry Program, Division of Community and Natural Resources, 2010; Green et al., 2015; Sene, 2020; Webb and Fa`aumu, 1999; Whistler, 2002; Whistler, 1994).

Nontree species are diverse. Examples of these include the native creeping and climbing fern lomagramma (Lomagramma cordipinna). Other ferns are Hawai'i birdnest fern (Asplenium nidus), musk fern (Microsorum grossum), giant sword fern (Nephrolepis biserrata), Asplenium marattioides, and cutleaf halberd fern (Tectaria dissecta). Two common epiphytic orchids are Dendrobium dactylodes and Dendrobium biflorum. Common lianas are sea bean (Mucuna gigantea), mamalupe (Faradaya amicorum), St. Thomas bean (Entada phaseoloides), and Gynochthodes epiphytica. Climbing vines include fue manogi (Piper graeffei) and entipede tongavine or fue laufao (Epipremnum pinnatum) Forestry Program, Division of Community and Natural Resources, 2010; Green et al., 2015; Sene, 2020; Webb and Fa`aumu, 1999; Whistler, 2002; Whistler, 1994).

Many species are not found in the USDA Plants Database.

Dominant plant species

(Dysoxylum), tree
nutmeg (Myristica), tree
(Lomagramma cordipinna), other herbaceous

Community 1.2
Tavai – Maota/Lomagramma

The same tree species as in Community Phase 1.1 remain in this phase, but other tree species, commonly tavai (Rhus taitensis) and maota (Dysoxylum maota) can join the canopy as the forest regrows. Ground vegetation becomes temporarily more abundant. Epiphytes are less common than in 1.1 (Forestry Program, Division of Community and Natural Resources, 2010; Green et al., 2015; Sene, 2020; Webb and Fa`aumu, 1999; Whistler, 2002; Whistler, 1994).

Dominant plant species

(Rhus taitensis), tree
(Dysoxylum), tree
(Lomagramma cordipinna), other herbaceous

Pathway 1.1A
Community 1.1 to 1.2

Storms or fires that damage or kill trees causes a phase change from 1.1 to 1.2 typified by a partial, temporary change in dominant tree species and a temporary increase in ground level vegetation.

Pathway 1.2A
Community 1.2 to 1.1

This community phase will revert to phase 1.1 with gradual regrowth of native species when given adequate time to recover after disturbance.

State 2
Naturalized Grassland

This state consists of two community phases that have been cleared of natural vegetation and planted or colonized with introduced grass species. It can be used for cattle grazing.

Dominant plant species

comb bushmint (Hyptis pectinata), shrub
nettleleaf velvetberry (Stachytarpheta urticifolia), shrub
para grass (Urochloa mutica), grass
hilograss (Paspalum conjugatum), grass
zarzabacoa comun (Desmodium incanum), other herbaceous
climbing dayflower (Commelina diffusa), other herbaceous

Community 2.1
Californiagrass/Spanish clover

This community phase is dominated by californiagrass (also called para grass) (Urochloa mutica). When not excessively grazed, it includes the legume Spanish clover (also called Zarabacoa comun) (Desmodium incanum). There may be small amounts of hilograss (Paspalum conjugatum) and climbing dayflower (Commelina diffusa) present (Forestry Program, Division of Community and Natural Resources, 2010; Green et al., 2015; Sene, 2020; Space and Flynn, 2000; Webb and Fa`aumu, 1999; Whistler, 2002; Whistler, 1994).

Dominant plant species

para grass (Urochloa mutica), grass
zarzabacoa comun (Desmodium incanum), other herbaceous

Community 2.2
Comb Bushmint – Nettleleaf Velvetberry/Californiagrass – Hilograss/Climbing Dayflower

This community phase consists largely of Californiagrass and some hilograss. Shrubs, vines, and forbs occupy some of the site due to reduction of grass competitiveness by excessive grazing. Some common species include mile-a-minute vine (Mikania micrantha); redflower rageleaf or fua lele (Crassocephalum crepidioides) a large, invasive forb; climbing dayflower (Commelina diffusa), a low-growing invasive forb; comb bushmint (Hyptis pectinata), a shrub; diamond burbark or mautofu (Triumfetta rhomboidea), a tall shrub; and nettleleaf velvetberry (Stachytarpheta urticifolia), a low shrub (Forestry Program, Division of Community and Natural Resources, 2010; Green et al., 2015; Sene, 2020; Space and Flynn, 2000; Webb and Fa`aumu, 1999; Whistler, 2002; Whistler, 1994).

Dominant plant species

comb bushmint (Hyptis pectinata), shrub
nettleleaf velvetberry (Stachytarpheta urticifolia), shrub
para grass (Urochloa mutica), grass
hilograss (Paspalum conjugatum), grass
climbing dayflower (Commelina diffusa), other herbaceous

Pathway 2.1A
Community 2.1 to 2.2

Community phase 2.1 will change to 2.2 by invasion of the site by shrubs and forbs. This process is facilitated by excessive grazing, which reduces the competitive advantage of Californiagrass.

Pathway 2.2A
Community 2.2 to 2.1

Community phase 2.2 can shift back to phase 2.1 by reducing grazing pressure on Californiagrass and, when necessary, performing spot weed control on shrubs and vines.

State 3
Cleared and Abandoned

This state consists of one community phase dominated by a variable mixture of small trees, shrubs, vines, forbs, and grasses that thrive in sunny environments. Remnant Californiagrass and hilograss are present.

Dominant plant species

lantana (Lantana camara), shrub
stickbush (Clerodendrum chinense), shrub
para grass (Urochloa mutica), grass
redflower ragleaf (Crassocephalum crepidioides), other herbaceous
mile-a-minute (Mikania micrantha), other herbaceous

Community 3.1
Lantana – Honolulu Rose/Fua Lele/Mile-A-Minute Vine/Californiagrass

This community phase remnant stands of Californiagrass and hilograss with a variable array of shrubs, forbs, vines, and young trees that thrive in sunny environments. Shrubs such as lantana (Lantana camara), stickbush or Honolulu rose (Clerodendrum chinense), comb bushmint (Hyptis pectinata), mautofu (Triumfetta rhomboidea), and nettleleaf velvetberry (Stachytarpheta urticifolia) are dominant. The shrub layer may also include seedlings and saplings of any native trees that may have persisted on or near the site or invasive, introduced tree species such as African tuliptree (Spathodea campanulata), red beadtree (Adenanthera pavonina), and tamaligi or peacocksplume (Falcataria moluccana). Mile-a-minute vine (Mikania micrantha) and the large, introduced forb fua lele (Crassocephalum crepidioides) may be present (Forestry Program, Division of Community and Natural Resources, 2010; Green et al., 2015; Sene, 2020; Space and Flynn, 2000; Webb and Fa`aumu, 1999; Whistler, 2002; Whistler, 1994).

Dominant plant species

lantana (Lantana camara), shrub
stickbush (Clerodendrum chinense), shrub
para grass (Urochloa mutica), grass
redflower ragleaf (Crassocephalum crepidioides), other herbaceous
mile-a-minute (Mikania micrantha), other herbaceous

State 4
Invaded Forest State

This state consists of one community phase. It is forested with both overstory, and understory composed of a variable mix of native and introduced species. The actual species composition on a given site depends on the original native species composition, the disturbance history, and the species composition existing near the site before, during, and after disturbances (Forestry Program, Division of Community and Natural Resources, 2010; Green et al., 2015; Sene, 2020; Space and Flynn, 2000; Webb and Fa`aumu, 1999; Whistler, 2002; Whistler, 1994).

Dominant plant species

(Dysoxylum), tree
African tuliptree (Spathodea campanulata), tree
soapbush (Clidemia hirta), shrub
running mountaingrass (Oplismenus compositus), grass
mile-a-minute (Mikania micrantha), other herbaceous

Community 4.1
Mamala – African tuliptree/Koster’s Curse/ Mile-A-Minute Vine/Running Mountaingrass

The overstory consists of large trees. Any of the native species listed for State 1 Reference may be present. Introduced tree species are likely to be present; common examples of these are African tuliptree (Spathodea campanulata), tamaligi or peacocksplume (Falcataria moluccana), and red beadtree (Adenanthera pavonina).

The understory consists of an unpredictable mixture of native and introduced shrubs, ferns, vines, forbs, and grasses that have some shade tolerance. See State 1 Reference for examples of native species. Common examples of introduced understory species are the shrubs soapbush or Koster’s curse (Clidemia hirta) and Honolulu rose (Clerodendrum chinense), mile-a-minute vine (Mikania micrantha) and running mountaingrass (Oplismenus compositus) (Forestry Program, Division of Community and Natural Resources, 2010; Green et al., 2015; Sene, 2020; Space and Flynn, 2000; Webb and Fa`aumu, 1999; Whistler, 2002; Whistler, 1994).

Dominant plant species

(Dysoxylum), tree
African tuliptree (Spathodea campanulata), tree
soapbush (Clidemia hirta), shrub
running mountaingrass (Oplismenus compositus), grass
mile-a-minute (Mikania micrantha), other herbaceous

Transition T1A
State 1 to 2

The Reference State (1) transitions to the Naturalized State (2) by removal of native vegetation and planting, or allowing colonization by, introduced grass species.

Transition T1B
State 1 to 3

The Reference State (1) transitions to the Cleared and Abandoned State (3) if previously cleared of forest and then abandoned. This allows heliophytes, both native and introduced, to temporarily cover the ground.

Transition T1C
State 1 to 4

The Reference State (1) transitions to the Invaded Forest State (4) by wind damage to the forest when there is a nearby source of seeds of invasive species or, more gradually, by damage to the forest understory by ungulates, especially feral pigs, when there is a source of seeds of invasive species.

Restoration pathway R2A
State 2 to 1

The Naturalized Grassland State (2) could theoretically be restored to the Reference State (1) by suppression of grassland vegetation and replanting with native species. Natural reseeding by native forest species can be expected if there is a nearby stand of suitable species.

Transition T2B
State 2 to 3

The Naturalized Grassland State (2) transitions to the Cleared and Abandoned State (3) with abandonment of grasslands, which are invaded by low-statured, native or introduced heliophytes.

Restoration pathway R3B
State 3 to 1

The Cleared and Abandoned State (3) may be restored to the Reference State (1). The intensity of active restoration measures will be determined by the presence or lack of nearby native forest or, at least, some native trees as well as the density and species mix of grasses, vines, shrubs, and invasive trees present on the site, especially if many competitive introduced species are present.

Restoration pathway R3A
State 3 to 2

The Cleared and Abandoned State (3) may be restored to the Naturalized Grassland State by land clearing, weed control, and replanting grasses.

Transition T3A
State 3 to 4

The Cleared and Abandoned State (3) transitions to the Invaded Forest State (4) by growth of an overstory of trees with an understory of shade-tolerant shrubs, vines, ferns, forbs, and grasses. The species mix is variable but may be mostly introduced species or a combination of native and introduced species.

Restoration pathway R4A
State 4 to 1

The Invaded Forest State (4) can be restored to the Reference State (1). The difficulty, cost, and likelihood of success will depend on the species composition and amount and competitiveness of introduced species present on a given site.

Restoration pathway R4B
State 4 to 3

The Invaded Forest State (4) can be restored to the Cleared and Abandoned State (3). After this “restoration,” State 3 is likely to rapidly transition back to State 4 due to presence of an abundant tree seed bank in the soil.

Additional community tables

Table 5. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 6. Community 1.2 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 7. Community 2.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 8. Community 2.2 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 9. Community 3.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 10. Community 4.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Supporting information

Inventory data references

NASIS soil component data.

Other references

Forestry Program, Division of Community and Natural Resources. (2010). American Samoa Forest Assessment and Resource Strategy. American Samoa Community College, Pago Pago, American Samoa.

Green, K., Kittel, G., Lopez, C., Ainsworth, A., Selvig, M., Vaivai, V., Akamine, K., Tukman, M., and Kudray, G. (2015). Vegetation Mapping Inventory Project, National Park of American Samoa. USDI-NPS Natural Resource Stewardship and Science. Fort Collins, Colorado.

Sene D. M. (2020). Forest Action Plan. Forestry Program, American Samoa Community College, Pago Pago, American Samoa.

Space J. C. and Flynn, T. (2000). Observations on invasive plant species in American Samoa. USDA Forest Service, Pacific Southwest Research Station, Honolulu. http://www.hear.org/pier/references/pierref000021.htm

USDA-NRCS. (2006). Major Land Resource Regions. USDA Agriculture Handbook 296. http://soils.usda.gov/MLRAExplorer

USDA-SCS. (1984). Soil Survey of Islands of American Samoa. Nakamura, S., Chavez, C. L. and Roybal, M. W., in cooperation with the Government of American Samoa.

USDI-FWS. (1982). Wildlife and Wildlife Habitat of American Samoa. II. Accounts of Flora and Fauna. R Banks, editor. Washington DC.

Webb, E. L .and Fa`aumu, S. (1999). Diversity and structure of tropical rain forest of Tutuila, American Samoa: effects of site age and substrate. Plant Ecology 44: 257-274.

Whistler, W. A. (2002). The Samoan Rainforest. Isle Botanica, Honolulu.

Whistler, W. A. (1994). Botanical Inventory of the Proposed Tutuila and Ofu Units of the National Park of American Samoa. Technical Report 87. National Park Service. Honolulu.

Contributors

David Clausnitzer PhD
Carolyn Aueweloa
John Proctor
Ann Tan
Daniel Bowman
Jennifer Fedenko
Amy Koch
Kendra Moseley
Sarah Quistberg
Daniel Block
Brendan Brazee
Curtis Talbot
Jill Ficke-Beaton

Approval

Jamin Johanson, 8/21/2026

Acknowledgments

Assistance, advice, review, and/or insights: Michael Constantinides, NRCS-PIA Jennifer Higashino, USFWS and NRCS Mike Kolman, NRCS

Rangeland health reference sheet

Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.

Author(s)/participant(s)
Contact for lead author
Date	06/11/2026
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):

Dominant:

Sub-dominant:

Other:

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
Perennial plant reproductive capability:

Download reference sheet

Natural ResourcesConservation Service

Ecological site QX197X01X504

Alluvial Valley Forest

Last updated: 8/21/2026 Accessed: 10/16/2026

Search

General information

MLRA notes

Classification relationships

Ecological site concept

Associated sites

Table 1. Dominant plant species

Legacy ID

Natural Resources
Conservation Service

Last updated: 8/21/2026
Accessed: 10/16/2026