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Ecological site QX191X01X501

Excessively and Somewhat Excessively Drained Coastal Strand

Last updated: 6/12/2025
Accessed: 10/19/2025

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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): 191X–High Limestone Plateaus of the Mariana Islands

This MLRA consists of the northern half of Guam and the islands of Saipan), Tinian, Rota, and Aguijan. Topography consists mostly of limestone plateaus. The highest elevations are 1,700 feet (520 meters) on Rota, 1,485 feet (450 meters) on Saipan, 655 feet (200 meters) on Tinian, and 860 feet (260 meters) in the northern part of Guam. The limestone plateaus were uplifted by tectonic activity. Deeply weathered volcanic rock is exposed on some ridges and slopes. Average annual rainfall is about 100 inches (2,540 millimeters) on northern Guam and about 80 inches (2,030 millimeters) on Saipan, Tinian, Aguijan, and Rota. The rainy season occurs from July through November; the dry season occurs from December through June. Trade winds blow from the northeast. Average annual temperature is 79 degrees F (26 degrees C). Typhoons are frequent. Soils are Alfisols, Andisols, Entisols, Mollisols, or Oxisols. The dominant soil moisture regime is ustic. The soil temperature regime is isohyperthermic. Native vegetation consists of mixed tropical hardwoods; introduced white leadtree or tangantangan trees (Leucaena leucocephala) are abundant. Introduced deer, pigs, goats, and water buffalo are common (USDA-NRCS, 2006). The main human disturbance is clearing land for cultivation. Feral pigs, feral cattle, brown tree snakes, stray dogs (Boonie dogs), and introduced deer are destructive to the native forest (Amand, 2000; CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Willsey et al., 2019).

Classification relationships

This ecological site occurs within Major Land Resource Area (MLRA) 191 – High Limestone Plateaus of the Mariana Islands.

Ecological site concept

This ecological site occurs on the islands of Guam, Saipan, Tinian, and Rota in the Mariana Islands. It occurs on nearly level to gently sloping (0 to 10 percent slopes) shorelines of coastal plains and on low coastal limestone plateaus at elevations ranging from 0 to 30 feet (0 to 10 meters). It occurs mostly on the leeward coast, but it occurs also on the windward side of southern Guam near river outlets (USDA-SCS, 1988; USDA-SCS, 1989). It is most easily accessible on the northeastern coast of Rota.

Soils are Ustipsamments and Haplustolls that formed in water-deposited coral sand and coralline limestone deposited in narrow zones parallel to the seashore (USDA-SCS, 1988; USDA-SCS, 1989). Soil temperature regimes are isohyperthermic; soil moisture regimes are ustic. The average annual precipitation is 87 inches (2,210 millimeters) and ranges from 83 to 91 inches (2,110 to 2,310 millimeters) (PRISM, 2006). Water runoff is very low to low; permeability is moderate to rapid (USDA-SCS, 1988; USDA-SCS, 1989). Effective rooting depth ranges from 6 to greater than 72 inches (15 to 185 centimeters). In soils with shallow rooting depth, roots penetrate deeper along fractures in the underlying limestone. Available water-holding capacity is very low to low (0 to 3 inches). Windborne salt spray and rare flooding by seawater help determine the vegetation type. Much of this ecological site is forested, but thin bands of small herbaceous plants, shrubs, and scrub forest typically occupy the zone closest to the ocean (Amidon et al., 2017; Fosberg, 1960; Liu and Fischer, 2008; Plentovich et al., 2020; Stone, 1970; Wagner and Grether, 1948; Willsey et al., 2019).

Associated sites

QX191X01X505	Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Soils of QX191X01X505 (Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. They are well drained. Subsurface soils contain 0 to 40 percent rock fragments greater than 3 inches. Effective rooting depth is very shallow to shallow (6 to 16 inches); available water holding capacity is very low (1 inch). At lowest elevations or just above sea level, it can be affected by salt spray from the sea. Soils of QX191X01X501 (Excessively Drained Coastal Strand Ecological Site) formed in coral sand near the sea and fine materials over limestone where it borders inland limestone plateaus and escarpments. They are somewhat excessively to excessively drained. Effective rooting depth is very shallow to very deep (6 inches to greater than 72 inches); available water holding capacity is very low to low (0 to 3 inches). Windborne salt spray and rare flooding by seawater affect the entire area. Both ecological sites are mostly forested but with different, mostly native, species. Where they border each other, there is a mix of species from each ecological site.
QX191X01X503	Very Shallow to Moderately Deep Soils on Limestone Plateaus Soils of QX191X01X503 (Very Shallow to Moderately Deep Soils on Limestone Plateaus Ecological Site) formed in fine materials over porous coralline or argillaceous limestone. They are well drained. Subsurface soils contain 0 to 12 percent rock fragments greater than 3 inches. Effective rooting depth is very shallow or shallow (2 to 20 inches); available water holding capacity is very low to low (1 to 3 inches). QX191X01X501 (Excessively Drained Coastal Strand Ecological Site) formed in coral sand near the sea and fine materials over limestone where it borders inland limestone plateaus and escarpments. They are somewhat excessively to excessively drained. Effective rooting depth is shallow to very deep (6 to greater than 72 inches); available water holding capacity is very low to low (0 to 3 inches). Windborne salt spray and rare flooding by seawater affect the entire area. It is mostly forested, while much of the area of the Very Shallow to Moderately Deep Soils on Limestone Plateaus Ecological Site is farmed. Where not farmed, vegetation consists of mostly introduced grass, forb, and tree species.
QX191X01X502	Deep and Very Deep Soils on Limestone Plateaus Soils of QX191X01X502 (Deep and Very Deep Soils on Limestone Plateaus Ecological Site) occur on plateaus. They are deep and very deep and moderately well to well drained. Available water holding capacity is moderately low (3 to 6 inches). Most of this ecological site is used for farmland; areas not farmed are vegetated by mostly introduced grass, forb, and tree species. Soils of QX191X01X501 (Excessively and Somewhat Excessively Drained Coastal Strand Ecological Site) occur on shorelines; they experience occasional flooding. They are somewhat excessively and excessively drained loamy sands, with very low to low (0 to 3 inches) available water holding capacity, and basic soils (pH ranges from 7.4 to 8.4). Windborne salt spray and rare flooding by seawater affect the entire area. Much of this ecological site is forested, but thin bands of small herbaceous plants, shrubs, and scrub forest typically occupy the zone closest to the ocean.
QX191X01X506	Somewhat Poorly and Poorly Drained Valley Bottoms and Coastal Plains Soils of QX191X01X506 (Somewhat Poorly and Poorly Drained Valley Bottoms and Coastal Plains Ecological Site) occur on valley bottoms and alluvial coastal plains. They are somewhat poorly or poorly drained. They have low (5 to 6 inches) water holding-capacity. Most of the area is vegetated by grasses, forbs, and wetland forest. Soils of QX191X01X501 (Excessively and Somewhat Excessively Drained Coastal Strand Ecological Site) occur on shorelines; they experience occasional flooding. They are excessively and somewhat excessively drained loamy sands, with very low to low (0 to 3 inches) available water holding capacity, and basic soils (pH ranges from 7.4 to 8.4). Windborne salt spray and rare flooding by seawater affect the entire area. Much of this ecological site is forested, but thin bands of small herbaceous plants, shrubs, and scrub forest typically occupy the zone closest to the ocean.
QX191X01X001	Moderately Deep Oxic Soils on Volcanic Uplands Soils of QX191X01X001 (Moderately Deep Oxic Soils on Volcanic Uplands Ecological Site) occur on hillslopes; they do not flood or pond. They are moderately deep (about 33 inches), well drained, have moderately low (5 inches) available water holding capacity, and strongly to moderately acid (pH ranges from 5.0 to 5.6), and a base saturation that is less than 35 percent. Most of the area is vegetated by Pacific Island silvergrass or swordgrass (Miscanthus floridulus). Soils of QX191X01501 (Excessively and Somewhat Excessively Drained Coastal Strand Ecological Site) occur on shorelines; they experience occasional flooding. They are excessively and somewhat excessively well drained loamy sands, with very low to low (0 to 3 inches) available water holding capacity, and basic soils (pH ranges from 7.4 to 8.4). Windborne salt spray and rare flooding by seawater affect the entire area. Much of this ecological site is forested, but thin bands of small herbaceous plants, shrubs, and scrub forest typically occupy the zone closest to the ocean.
QX191X01X002	Moderately Deep Alfic Soils on Volcanic Uplands Soils of QX191X01X002 (Moderately Deep Alphic Soils on Volcanic Uplands Ecological Site) occur on uplands; they do not flood or pond. They are moderately deep, well drained, have low (5 inches) available water holding capacity, and slightly basic soils (pH ranges from 6.2 to 6.5) and a base saturation that is greater than or equal to 35 percent. Most of the area is vegetated by grasses, forbs, and mixed forest of introduced and native species. Soils of QX191X01X501 (Excessively and Somewhat Excessively Drained Coastal Strand Ecological Site) occur on shorelines; they experience occasional flooding. They are excessively and somewhat excessively well drained loamy sands, with very low (0 to 3 inches) available water holding capacity, and basic soils (pH ranges from 7.4 to 8.4). Windborne salt spray and rare flooding by seawater affect the entire area. Much of this ecological site is forested, but thin bands of small herbaceous plants, shrubs, and scrub forest typically occupy the zone closest to the ocean.
QX191X01X004	Somewhat Poorly and Poorly Drained Limestone Basins Soils of QX191X01X004 (Somewhat Poorly and Poorly Drained Limestone Basins Ecological Site) occur on basin floors; they rarely flood or pond. They are deep (40 to 60 inches), somewhat poorly and poorly drained, have low (6 inches) available water holding capacity, and slightly acid to slightly basic soils (pH ranges from 5.1 to 7.8). Most of the area is vegetated by water-tolerant grasses and forest. Soils of QX191X01X501 (Excessively and Somewhat Excessively Drained Coastal Strand Ecological Site) occur on shorelines; they experience occasional flooding. They are excessively and somewhat excessively well drained well drained loamy sands, with very low (0 to 3 inches) available water holding capacity, and basic soils (pH ranges from 7.4 to 8.4). Windborne salt spray and rare flooding by seawater affect the entire area. Much of this ecological site is forested, but thin bands of small herbaceous plants, shrubs, and scrub forest typically occupy the zone closest to the ocean.

Table 1. Dominant plant species

Tree	(1) Hernandia sonora (2) Calophyllum inophyllum
Shrub	Not specified
Herbaceous	(1) Phymatosorus scolopendria

Legacy ID

F191XY501MP

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Physiographic features

This ecological site occurs on the shorelines of coastal plains and on low elevation areas on adjacent limestone plateaus (USDA-SCS, 1988; USDA-SCS, 1989). The water table depth can range from 63 inches to greater than 72 inches (160 to 185 centimeters).

Table 2. Representative physiographic features

Landforms	(1) Coastal plain > Shore (2) Plateau
Runoff class	Very low to low
Flooding frequency	Rare
Ponding frequency	None
Elevation	30 ft
Slope	10%
Water table depth	72 in
Aspect	Aspect is not a significant factor

Climatic features

Summary for this Ecological Site

Rainfall statistics were determined from PRISM rainfall raster data (PRISM, 2006). Representative (20th and 80th percentiles) values for mean annual precipitation range from 83 to 91 inches (2,110 to 2,310 millimeters) while actual (10th and 90th percentiles) values for mean annual precipitation range from 80 to 98 inches (2,030 to 2,490 millimeters). Extreme values range from 77 to 103 inches (1,955 to 2,615 millimeters). The average annual precipitation is 87 inches (2,210 millimeters) and the median annual average precipitation is 84 inches (2,135 millimeters).

Temperature statistics were determined from PRISM temperature raster data (PRISM, 2006) Representative (20th and 80th percentiles) values for mean annual temperatures range from 81 to 81 degrees F (27 to 27 degrees C) while actual (10th and 90th percentiles) values for mean annual temperatures range from 81 to 82 degrees F (27 to 28 degrees C). Extreme values range from 81 to 82 degrees F (27 to 28 degrees C). The average annual temperature is 81 degrees F (27 degrees C), and the median annual temperature is also 81 degrees F (27 degrees C).

The data presented in the climate normals tables below are from select climate stations on Guam, Rota, and Saipan. I used the data from these stations because they are representative of the spatial distribution of this ecological site and because they provide a reasonably comparable approximation of the PRISM data presented above, e.g. the average annual precipitation is 89 inches (2260 millimeters), and the average annual temperature is about 80 degrees F (27 degrees C).

General Concepts for the Northern Mariana Islands

The climate of the Commonwealth of the Northern Mariana Islands is uniformly warm and humid throughout the year. Afternoon temperatures are normally about 86 degrees F (30 degrees C); nighttime temperatures are around 68 degrees F (20 degrees C). Relative humidity usually is about 70 percent in the afternoon and 90 percent at night. There are two main seasons in the Northern Mariana Islands, the dry season from December to June and the wet season from July to November. About two-thirds of the rain falls between July and November. Mean annual rainfall is about 80 inches (2,030 millimeters), although areas at higher elevations, such as the highest plateau (the Sabana) on Rota, probably receive almost 100 inches (2,540 millimeters) (Fosberg, 1960; USDA-SCS, 1988; USDA-SCS, 1989).

The dominant winds are the trade winds, which blow from the east or northeast. The trade winds are strongest and most constant during the dry season, when windspeeds of 15 to 24 miles per hour (25 to 40 kilometers per hour) are common. Coastal areas that have east, and northeast exposures are subject to salt spray and buffeting winds (Fosberg, 1960; USDA-SCS, 1988; USDA-SCS, 1989).

During the rainy season the trade winds may break down and be replaced by a weak, westerly monsoon influence that brings heavy showers or steady, sometimes torrential, rains. The Northern Mariana Islands lie in the path of typhoons from the southeast and east. They bring heavy rainfall and violent winds that may cause a surge of water onto low-lying coastal areas. Typhoons most frequently occur during the latter half of the year, but they have been recorded during every month of the year (Fosberg, 1960; USDA-SCS, 1988; USDA-SCS, 1989).

Table 3. Representative climatic features

Frost-free period (characteristic range)	365 days
Freeze-free period (characteristic range)	365 days
Precipitation total (characteristic range)	83-91 in
Frost-free period (actual range)	365 days
Freeze-free period (actual range)	365 days
Precipitation total (actual range)	80-98 in
Frost-free period (average)	365 days
Freeze-free period (average)	365 days
Precipitation total (average)	87 in

Characteristic range

Actual range

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Figure 1. Monthly precipitation range

Characteristic range

Actual range

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Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 3. Monthly maximum temperature range

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Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6. Annual average temperature pattern

Climate stations used

(1) ROTA AP [CQC00914801], MP
(2) ANDERSEN AFB GUAM [GQC00914025], GU
(3) CAPITOL HILL 1 [CQC00914080], MP

Soil features

The soil components associated with this ecological site are Shioya (Ensisols) and Takpochao Variant (Mollisols) (USDA-SCS, 1988; USDA-SCS, 1989).

These soils are Ustipsamments and Haplustolls which formed in water-deposited coral sand and coralline limestone deposited in narrow zones parallel to the seashore. Shioya soils are sandy and Takpochao Variant soils are loamy-skeletal. As such they are excessively to somewhat excessively drained. Soil depths range from very shallow to very deep (6 to greater than 72 inches). The Taokpochao variant is very shallow (4 inches). Soil temperature regimes are isohypothermic (very warm); Soil moisture regimes are ustic. The soils are sometimes (rarely) flooded by large ocean waves. The water table is greater than 72 inches (185 centimeters) below the soil surface.

Table 4. Representative soil features

Parent material	(1) Coral limestone
Surface texture	(1) Loamy sand
Family particle size	(1) Loamy-skeletal (2) Sandy
Drainage class	Somewhat excessively drained to excessively drained
Permeability class	Rapid
Depth to restrictive layer	6 – 72 in
Soil depth	6 – 72 in
Surface fragment cover <=3"	31%
Surface fragment cover >3"	9%
Available water capacity (0-40in)	2 – 3.3 in
Calcium carbonate equivalent (0-40in)	90%
Electrical conductivity (0-40in)	8 – 16 mmhos/cm
Sodium adsorption ratio (0-40in)	1
Soil reaction (1:1 water) (0-10in)	7.4 – 8.4
Subsurface fragment volume <=3" (0-40in)	11 – 31%
Subsurface fragment volume >3" (0-40in)	3 – 9%

Table 5. Representative soil features (actual values)

Drainage class	Not specified
Permeability class	Not specified
Depth to restrictive layer	Not specified
Soil depth	Not specified
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	Not specified
Calcium carbonate equivalent (0-40in)	Not specified
Electrical conductivity (0-40in)	16 mmhos/cm
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-10in)	Not specified
Subsurface fragment volume <=3" (0-40in)	Not specified
Subsurface fragment volume >3" (0-40in)	Not specified

Ecological dynamics

Although annual rainfall is high (average annual precipitation is 87 inches (2,210 millimeters)) and well distributed throughout much of the year, the moderate to rapid permeability of the sandy soils results in dry conditions as indicated by the low water holding capacity and the somewhat excessive to excessive drainage class of the soils. The deep ground water is saline or brackish, soil fertility is low, winds are laden with salt, and daytime soil surface temperatures are high where sunlight penetrates the canopy. These soil conditions limit the plant species able to thrive in this ecological site (Amidon et al., 2017; Fosberg, 1960; Liu and Fischer, 2008; Plentovich et al., 2020; Stone, 1970; Wagner and Grether, 1948; Willsey et al., 2019).

The main natural disturbance is strong storms that can damage or kill vegetation by wind and wave action. The main human disturbance is clearing of native vegetation to plant coconut plantations and abandonment of plantations that results in at least temporary dominance of introduced weedy plants (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Willsey et al., 2019).

State and transition model

Custom diagram

Standard diagram

Figure 7. State-and-Transition Model for the Excessively Drained Coastal Strand Ecological Site (F191XY501MP)

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Ecosystem states

1. Reference State

2. Coconut Plantation State

3. Abandoned State

T1A	-	The Reference State (1) transitions to the Coconut Plantation State (2) by removal of native vegetation and planting coconut palm (Cocos nucifera).
T1B	-	The Reference State (1) transitions to the Abandoned State (3) if cleared and abandoned. This allows heliophytes, both native and introduced, to temporarily cover the understory
T2A	-	The Coconut Plantation State (2) transitions to the Abandoned State (3) upon abandonment of coconut plantations, which are quickly invaded by low-statured, native and/or introduced heliophytes.
R3B	-	The 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 trees present on the site, especially if many competitive introduced species are present.
R3A	-	The Abandoned State (3) may be restored to the Coconut Plantation State (2) by land clearing, weed control, and replanting coconut palm (Cocos nucifera).

State 1 submodel, plant communities

1.1. Mago – Alexandrian Laurel/Monarch Fern

1.2. Beach Sheoak – Mago/Kuroiwa Grass

1.1A	-	Storms that disturb or kill trees causes a phase change from phase 1.1, which has all native tree species, to phase 1.2, which temporarily has an open stand of native trees with an understory of mostly native vines and grasses.
1.2A	-	Community phase 1.2 will revert to phase 1.1 with gradual regrowth of a more diverse array of native species when given adequate time to recover after disturbance.

State 2 submodel, plant communities

2.1. Coconut Palm

State 3 submodel, plant communities

3.1. Coconut Palm/Bay Biscayne Creeping-Oxeye (Wedelia)/Southern Sandbur

State 1
Reference State

This ecological site occupies a narrow area (forested strand) along the seacoast. Plant species are primarily salt-resistant heliophytes.

Community 1.1
Mago – Alexandrian Laurel/Monarch Fern

The forest floor is typically open, with no shrubs and very little ground cover due to shade. Dominant species vary among locations. Common tree species are mago (Hernandia sonora), sea putat (Barringtonia asiatica), artocarpus (Artocarpus mariannensis), Alexandrian laurel (Calophyllum inophyllum), beach sheoak (Casuarina equisetifolia), Portia tree (Thespesia populnea), Tahitian screwpine (Pandanus tectorius) and bakong (P. dubuis), velvetleaf soldierbush (Heliotropium foertherianum syn. Tournefortia argentea), Guettarda speciosa, neisosperma (Neisosperma oppositifolia), and tropical almond (Terminalia catappa). Coconut palm (Cocos nucifera) is native but uncommon in undisturbed forest; it is common only where it has been planted intentionally (Amidon et al., 2017; Fosberg, 1960; Liu and Fischer, 2008; Plentovich et al., 2020; Stone, 1970; Wagner and Grether, 1948; Willsey et al., 2019). In the understory or open areas may be found queen sago (Cycas circinalis), monarch fern (Phymatosorus scolopendria), notched cowpea (Vigna marina), devil’s gut (Cassytha filiformis), Leucaena insularum var. guamensis (shrub, no common name), Ochrosia mariannensis (tree, no common name), tiger’s claw (Erythrina variegata var. orientalis), kou (Cordia subcordata), seashore dropseed (Sporobolus virginicus), and Kuroiwa grass (Thuarea involuta), a mat-forming grass (Amidon et al., 2017; Fosberg, 1960; Liu and Fischer, 2008; Plentovich et al., 2020; Stone, 1970; Wagner and Grether, 1948; Willsey et al., 2019).

Dominant plant species

mago (Hernandia sonora), tree
Alexandrian laurel (Calophyllum inophyllum), tree
monarch fern (Phymatosorus scolopendria), other herbaceous

Community 1.2
Beach Sheoak – Mago/Kuroiwa Grass

The dominant species vary by location but consist of low stature heliophytes that temporarily occupy the ground, in addition to seedlings of the previously dominant tree species. Beach sheoak (Casuarina equisetifolia) is the main pioneer tree species in open areas. Kuroiwa grass (Thuarea involuta) is abundant (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Plentovich et al., 2020; Willsey et al., 2019).

Dominant plant species

beach sheoak (Casuarina equisetifolia), tree
Kuroiwa grass (Thuarea involuta), grass

Pathway 1.1A
Community 1.1 to 1.2

Storms that disturb or kill trees causes a phase change from phase 1.1, which has all native tree species, to phase 1.2, which temporarily has an open stand of native trees with an understory of mostly native vines and grasses.

Pathway 1.2A
Community 1.2 to 1.1

Community phase 1.2 will revert to phase 1.1 with gradual regrowth of a more diverse array of native species when given adequate time to recover after disturbance.

State 2
Coconut Plantation State

The Coconut Plantation State (2) consists of one community phase that has been cleared of natural vegetation and planted with coconut palm (Cocos nucifera).

Community 2.1
Coconut Palm

This community phase consists of planted coconut palm (Cocos nucifera). Highly variable low ground cover is present. Common understory species are premna (Premna obtusifolia), an introduced shrub or tree, Bay Biscayne creeping-oxeye or wedelia (Sphagneticola trilobata), an introduced forb, a dense stand of coconut seedlings, and southern sandbur (Cenchrus echinatus), an introduced grass species (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Plentovich et al., 2020; Willsey et al., 2019).

Dominant plant species

coconut palm (Cocos nucifera), tree

State 3
Abandoned State

The Abandoned State (3) consists of one community phase dominated by a variable mixture of native and introduced small trees, shrubs, vines, forbs, and grasses that thrive in sunny environments. Remnant coconut palm (Cocos nucifera) is likely present.

Community 3.1
Coconut Palm/Bay Biscayne Creeping-Oxeye (Wedelia)/Southern Sandbur

Community phase 3.1 contains a variable amount of remnant coconut palm (Cocos nucifera) with a variable understory of native and introduced shrubs, forbs, vines, and grasses that thrive in sunny environments. Bay Biscayne creeping-oxeye (Sphagneticola trilobata), also known as wedelia, is a weedy, introduced forb that can form a dense, competitive ground cover. Southern sandbur (Cenchrus echinatus) is a competitive, introduced grass. A wide variety of other species may occur depending on location of the site (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Plentovich et al., 2020; Willsey et al., 2019).

Dominant plant species

coconut palm (Cocos nucifera), tree
southern sandbur (Cenchrus echinatus), grass
Bay Biscayne creeping-oxeye (Sphagneticola trilobata), other herbaceous

Transition T1A
State 1 to 2

The Reference State (1) transitions to the Coconut Plantation State (2) by removing native vegetation and planting coconut palm (Cocos nucifera).

Transition T1B
State 1 to 3

The Reference State (1) transitions to the Abandoned State (3) if cleared and abandoned. This allows heliophytes, both native and introduced, to temporarily cover the understory.

Transition T2A
State 2 to 3

The Coconut Plantation State (2) transitions to the Abandoned State (3) upon abandonment of coconut plantations, which are quickly invaded by low-statured, native or introduced heliophytes.

Restoration pathway R3B
State 3 to 1

The 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 trees present on the site, especially if many competitive introduced species are present.

Restoration pathway R3A
State 3 to 2

The Abandoned State (3) may be restored to the Coconut Plantation State (2) by land clearing, weed control, and replanting coconut palm (Cocos nucifera).

Additional community tables

Supporting information

Other references

References for the Excessively Drained Coastal Strand Ecological Site (F191XY501MP)

Amand, A. (2000). Boiga irregularis (Brown Tree Snake) on Guam and Its Effect on Fauna. Restoration and Reclamation Review, 6 1-6.

Amidon, F., Metevier, M., and Miller, S. E. (2017). Vegetation Mapping of the Mariana Islands: Commonwealth of the Northern Mariana Islands and Territory of Guam. US Fish and Wildlife Service and Pacific Islands Climate Change Cooperative. Final Report November 2017.

CNMI SWARS Council. (2010). Commonwealth of the Northern Mariana Islands (CNMI) Statewide Assessment and Resource Strategy 2010-2015+. CNMI Forestry.

Donnegan, J. A., Butler, S. L., Kuegler, O., and Hiserote, B. A. (2011). Commonwealth of the Northern Mariana Islands’ Forest resources Resource. Bull. PNW-RB-261. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 40 p.

Fosberg, F. R. (1960). The Vegetation of Micronesia. I. General descriptions, the vegetation of the Marianas Islands, and a detailed consideration of the vegetation of Guam. Bulletin of the American Museum of Natural History 199:1.

Liske-Clark, J. (2015). Wildlife Action Plan for the Commonwealth of the Northern Mariana Islands, 2015-2025. CNMI DLRN-Division of Fish and Wildlife, Saipan, MP.

Liu, Z., and Fischer, L.. (2008). Commonwealth of the Northern Mariana Islands Vegetation Mapping Using Very High Spatial Resolution Imagery. USDA Forest Service Pacific Southwest Region, Forest Health Protection, McClellan, CA.

Plentovich, S., Mizerek, T., Reeves, M. K., Amidon, F., Miller, S. E., and Nanbara, M., (2020). Coastal Strand and Mangrove Swamps of the Mariana Islands. In: Goldstein, M.I., DellaSala, D.A. (Eds.), Encyclopedia of the World's Biomes, vol. 1. Elsevier, pp. 185–197.

PRISM Climate Group, Oregon State University. (2006). https://prism.oregonstate.edu, data created 4 Feb 2014, accessed 09 Oct 2024. Pacific Islands Project: Average monthly precipitation, minimum and maximum temperature, relative humidity, and mean dew point temperature for the period 1971-2000 (completed 2006). Covers Hawaii, Kosrae, Manua, Pohnpei, Tutuila, Guam, CNMI, and Palau. Project sponsored by USDA Natural Resources Conservation Service.

Stone, B. C. (1970). The Flora of Guam. A Manual for the Identification of the Vascular Plants of the Island. Micronesica – Journal of the University of Guam, vol. 6, July 1970.

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

USDA-Soil Conservation Service. (1988). Soil Survey of Territory of Guam.

USDA-Soil Conservation Service. (1989). Soil Survey of the Islands of Aguijan, Rota, Saipan, and Tinian, Commonwealth of the Northern Mariana Islands.

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Wagner, W. H. and Grether, D. F. (1948). The Pteridophytes of Guam. Occasional Papers of Bernice P. Bishop Museum, volume XIX, number 2. Honolulu, Hawaii.

Willsey, T., Kwon, J. A., Reeves, M. K., Amidon, F., and Miller, S. E. (2019). Mariana Islands Forest. Encyclopedia of the World's Biomes. https://doi.org/10.1016\B978-0-12-409548-9.12012-3

Contributors

David Clausnitzer PhD
John Proctor
Ann Tan
Jennifer Fedenko
Daniel Bowman
Amy Koch
Kendra Moseley
Brendan Brazee
Sarah Quistberg

Approval

Kendra Moseley, 6/12/2025

Acknowledgments

Assistance, advice, review, and/or insights:

Michael Constantinides, NRCS-PIA
Jennifer Higashino, USFWS and NRCS
Mike Kolman, NRCS
Bart Lawrence, NRCS
Carolyn Auweloa, NRCS
Jay Doronila, NRCS
Pamela Sablan, NRCS
Michael 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	06/12/2025
Approved by	Kendra Moseley
Approval date
Composition (Indicators 10 and 12) based on	Annual Production