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Ecological site QX191X01X505

Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments

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 100 inches (2,540 millimeters) on northern Guam and 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 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, Aguijan, and Rota in the Mariana Islands. It occurs on nearly level to very steep (0 to 99 percent slopes) limestone plateaus and escarpments at elevations ranging from 0 to 1570 feet (0 to 480 meters) (USDA-SCS, 1988; USDA-SCS, 1989).

Soils are very shallow to shallow, well drained Mollisols and Entisols that formed in sediment, colluvium, loess, and residuum over porous coralline limestone. Soil temperature regimes are isohyperthermic; soil moisture regimes are ustic. Average annual precipitation is about 91 inches (2,310 millimeters) and ranges from 80 to 101 inches (2,030 to 2,565 millimeters) (PRISM, 2006). Water runoff is very low to high; permeability is moderate or moderately rapid. Effective rooting depth ranges from 2 to 16 inches (5 to 40 cm). Available water-holding capacity is very low (1 inch) (USDA-SCS, 1988; USDA-SCS, 1989). Most of the area is vegetated by native forest. In windward low-elevation areas that receive salt spray the vegetation consists of shrubs and low trees (Amidon et al., 2017; Falanruw et al., 1989; Fosberg, 1960; Liu and Fischer, 2008; Stone, 1970; Wagner and Grether, 1948; Willsey et al., 2019).

Associated sites

QX191X01X501	Excessively and Somewhat Excessively Drained Coastal Strand QX191X01X501 (The 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. Effective rooting depth is 4 to 79 inches; available water holding capacity is very low to low (3 inches). Windborne salt spray and rare flooding by seawater affect the entire area. Soils of QX191X01X505 (The Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. Effective rooting depth is very shallow to shallow (2 to 16 inches); available water holding capacity is very low (1 inches). Most of the area is vegetated by native forest. This ecological site is limited to an area that is often shrouded in clouds and fog. Moisture is added to the soil by fog drip, which maintains soils in moist condition most of the time. 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.
QX192X01X001	Moderately Deep Oxic Soils on Volcanic Uplands Soils of QX192X01X001 (The Moderately Deep Oxic Soils on Volcanic Uplands Ecological Site) formed in volcanic materials and have effective rooting depths range from 16 to 45 inches, low to moderate available water holding capacity (2 to 7 inches), low base saturation, low pH, and aluminum toxicity. Most of the area is vegetated by Pacific silver grass or swordgrass (Miscanthus floridulus). Soils of QX191X01505 (The Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. Effective rooting depth is very shallow to shallow (2 to 16 inches); available water holding capacity is very low (1 inches). Most of the area is vegetated by native forest. This ecological site is limited to an area that is often shrouded in clouds and fog. Moisture is added to the soil by fog drip, which maintains soils in moist condition most of the time.
QX192X01X002	Deep Alfic Soils on Volcanic Uplands Soils of QX192X01X002 Very Deep Alfic Soils on Volcanic Uplands formed in volcanic materials and have effective rooting depth which are moderately deep (20 inches) to deep (40 inches); low available water holding capacity (4 inches), fairly high base saturation, pH above 5.0, and no aluminum toxicity. Most of the area is vegetated by forest, grasses, and forbs. Soils of QX191X01505 (The Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. Effective rooting depth is very shallow to shallow (2 to 16 inches); available water holding capacity is very low (1 inches). Most of the area is vegetated by native forest. This ecological site is limited to an area that is often shrouded in clouds and fog. Moisture is added to the soil by fog drip, which maintains soils in moist condition most of the time.
QX192X01X003	Shallow Soils on Volcanic Uplands Soils of QX192X01X003 (The Very Shallow and Shallow Soils on Volcanic Uplands Ecological Site) formed in volcanic materials, have effective rooting depth which are shallow (4 to 15 inches), and have very low available water holding capacity (2 inches). Most of the area is vegetated by grasses, forbs, and forest. Soils of Soils of QX191X01505 (The Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. Effective rooting depth is very shallow to shallow (2 to 16 inches); available water holding capacity is very low (1 inches). Most of the area is vegetated by native forest. This ecological site is limited to an area that is often shrouded in clouds and fog. Moisture is added to the soil by fog drip, which maintains soils in moist condition most of the time.
QX191X01X502	Deep and Very Deep Soils on Limestone Plateaus Soils of QX191X01X502 (The Deep and Very Deep Soils on Limestone Plateaus Ecological Site) formed in fine materials over porous coralline or argillaceous limestone. Effective rooting depth is 40 to 59 inches or deeper and available water holding capacity is low (4 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. Tangantangan (Leucaena leucocephala) is abundant in places. Soils of QX191X01505 (The Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. Effective rooting depth is very shallow to shallow (2 to 16 inches); available water holding capacity is very low (1 inches). Most of the area is vegetated by native forest. This ecological site is limited to an area that is often shrouded in clouds and fog. Moisture is added to the soil by fog drip, which maintains soils in moist condition most of the time.
QX191X01X506	Somewhat Poorly and Poorly Drained Valley Bottoms and Coastal Plains Soils of QX191X01X506 (The Somewhat Poorly and Poorly Drained Valleys and Alluvial Coastal Plains Ecological Site) are in broad river valley bottoms and narrow coastal plains. Soils formed in alluvium or beach deposits, have aquic moisture regimes, moderately deep water tables, areas of slightly brackish groundwater, and are occasionally flooded. Most of the area is vegetated by grasses, forbs, and wetland forest. QX191X01505 (The Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. Effective rooting depth is very shallow to shallow (2 to 16 inches); available water holding capacity is very low (1 inches). Most of the area is vegetated by native forest. This ecological site is limited to an area that is often shrouded in clouds and fog. Moisture is added to the soil by fog drip, which maintains soils in moist condition most of the time.
QX191X01X002	Moderately Deep Alfic Soils on Volcanic Uplands Soils of QX191X01X002 (The Moderately Deep Alfic Soils on Volcanic Uplands Ecological Site) formed in volcanic uplands from residuum derived from andesitic marine tuff and tuffaceous breccia. They are highly weathered Alfisols that have fairly high base saturation, effective rooting depths of 20 to 40 inches, surface pH ranging from 5.5 to 5.8, and low (5 inches) available water holding capacity. Most of the area is vegetated by grasses, forbs, and mixed forest of introduced and native species. Swordgrass (Miscanthus floridulus) is present in some areas. white leadtree or Tangantangan (Leucaena leucocephala) is not abundant. Soils of QX191X01505 (The Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. Effective rooting depth is very shallow to shallow (2 to 16 inches); available water holding capacity is very low (1 inches). Most of the area is vegetated by native forest. This ecological site is limited to an area that is often shrouded in clouds and fog. Moisture is added to the soil by fog drip, which maintains soils in moist condition most of the time.
QX191X01X001	Moderately Deep Oxic Soils on Volcanic Uplands Soils of QX191X01X001onin volcanic uplands in residuum and colluvium derived from volcanic tuff and tuff breccia. They are highly weathered Oxisols that have low base saturation, a rooting depth of about 30 inches, surface pH of about 5.0 to 5.6, and aluminum toxicity that limits growth of most plant species. Most of the area is vegetated by swordgrass (Miscanthus floridulus). QX191X01505 (The Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments Ecological Site) formed in fine materials over porous coralline limestone. Effective rooting depth is very shallow to shallow (2 to 16 inches); available water holding capacity is very low (1 inches). Most of the area is vegetated by native forest. This ecological site is limited to an area that is often shrouded in clouds and fog. Moisture is added to the soil by fog drip, which maintains soils in moist condition most of the time.

Table 1. Dominant plant species

Tree	(1) Artocarpus mariannensis (2) Merrilliodendron megacarpum
Shrub	(1) Freycinetia reineckei
Herbaceous	Not specified

Legacy ID

F191XY505MP

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Physiographic features

This ecological site occurs on limestone plateaus and escarpments (USDA-SCS, 1988; USDA-SCS, 1989). The depth to the water table is greater than 72 inches (185 centimeters).

Table 2. Representative physiographic features

Landforms	(1) Plateau
Runoff class	Very low to high
Flooding frequency	None
Ponding frequency	None
Elevation	1,570 ft
Slope	99%
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 80 to 101 inches (2,030 to 2,565 millimeters) while actual (10th and 90th percentiles) values for mean annual precipitation range from 76 to 105 inches (1,930 TO 2,670 millimeters). Extreme values range from 69 to 122 inches (1,750 to 3,100 millimeters). The average annual precipitation is 91 inches (2,310 millimeters) and the median annual average precipitation is 92 inches (3,335 millimeters).

Temperature statistics were determined from PRISM temperature raster data (PRISM, 2006) Representative (20th and 80th percentiles) values for mean annual temperatures range from 79 to 81 degrees F (26 to 27 degrees C) while actual (10th and 90th percentiles) values for mean annual temperatures range from 77 to 81 degrees F (25 to 27 degrees C). Extreme values range from 75 to 82 degrees F (24 to 28 degrees C). The average annual temperature is 79 degrees F (26 degrees C), and the median annual temperature is 81 degrees F (27 degrees C).

The data presented in the climate normals tables below are from select climate stations in 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 the values for mean annual rainfall of 91 inches (2,310 millimeters) and mean annual temperature values of 80 degrees F (27 degrees C) are reasonably comparable.

General Principles

The climate is uniformly warm and humid throughout the year. Afternoon temperatures typically are about 86 degrees F (30 degrees C); nighttime temperatures are about 68 F (20 C). Relative humidity is 65 to 75 percent in the afternoon to 85 to 100 percent at night. Though temperature and humidity vary only slightly throughout the year, rainfall and wind conditions vary markedly. There are two main seasons, the dry season from December through June and the rainy season from mid-July to mid-November. Moisture deficit occurs between January and June. Mean annual rainfall ranges from about 98 inches (2,490 millimeters) on the windward (eastern) side of the higher mountains to about 79 inches (2,005 millimeters) along the coast of the western side of the islands. On average, about 15 percent of the annual rainfall occurs during the dry season and 55 percent during the rainy season (Fosberg, 1960; USDA-SCS, 1988; USDA-SCS, 1989).

Throughout the year, the dominant winds are the trade winds that blow from the east or northeast. The trade winds are strongest and most constant during the dry season, when windspeeds of 15 to 25 mph (25 to 40 kph) 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 and sometimes torrential rains. The islands lie in the path of typhoons from the southeast and east. They bring heavy rains and violent winds that may result in a surge of water onto low-lying coastal areas. They occur most frequently during the latter half of the year. The chance of having one or more typhoons pass close to the islands in any particular year is about once in three years. The chance of having a typhoon move directly across an island is about once in eight years (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)	80-101 in
Frost-free period (actual range)	365 days
Freeze-free period (actual range)	365 days
Precipitation total (actual range)	76-105 in
Frost-free period (average)	365 days
Freeze-free period (average)	365 days
Precipitation total (average)	91 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) CAPITOL HILL 1 [CQC00914080], MP
(2) ROTA AP [CQC00914801], MP
(3) ANDERSEN AFB GUAM [GQC00914025], GU
(4) GUAM INTL AP [GQW00041415], GU

Influencing water features

Number of National Wetland Inventory (NWI) features overlapping ecological site: Freshwater forested/shrub wetlands (161), estuarine and marine wetland (145), freshwater emergent wetlands (143), riverine (115), estuarine and marine deepwater (49), and freshwater pond (11) (USFWS, 2023).

Soil features

The soils associated with this ecological site are Ritidan, Luta, and Takpochao. They are very shallow to shallow, well drained Mollisols and Entisols that formed in sediment, colluvium, loess, and residuum over porous coralline limestone. Soil temperature regimes are isohyperthermic; soil moisture regimes are ustic. Effective rooting depth ranges from 2 to 16 inches (5 to 40 cm). Available water-holding capacity is very low (1 inch) (USDA-SCS, 1988; USDA-SCS, 1989).

Table 4. Representative soil features

Parent material	(1) Colluvium – limestone (2) Loess – limestone (3) Residuum – limestone
Surface texture	(1) Cobbly clay loam (2) Medial clay loam (3) Extremely cobbly clay loam (4) Very cobbly clay
Family particle size	(1) Loamy (2) Clayey-skeletal
Drainage class	Well drained
Permeability class	Moderate to moderately rapid
Depth to restrictive layer	2 – 16 in
Soil depth	2 – 16 in
Surface fragment cover <=3"	24%
Surface fragment cover >3"	40%
Available water capacity (0-40in)	0.5 – 1.5 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) (0-10in)	7 – 7.2
Subsurface fragment volume <=3" (0-40in)	24%
Subsurface fragment volume >3" (0-40in)	40%

Ecological dynamics

Most of this ecological site is vegetated by forest. Other land uses are rare because of the steepness or rockiness of the terrain and soils. The main human-related disturbance is from feral pigs, feral cattle, and introduced deer that browse and graze in the forest. Some sites have been cleared by humans; they rapidly revert to forest in most cases (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Willsey et al., 2019).

The main natural disturbance is strong storms that can damage or kill vegetation by high wind speeds. Natural fire is rare in forested areas due to the low amount of fine fuels on the ground. The lower elevations near the ocean are affected by salt spray (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 F191XY505MP (Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments).

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Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Reference State

2. Cleared and Abandoned State

3. Grazed Woodland State

T1A	-	The Reference State (1) may transition to Cleared and Abandoned State (3) by clearing the forest, temporary cultivation of crops, abandonment, and invasion by mostly introduced species.
R2A	-	The Cleared and Abandoned State (2) can be restored to a facsimile of Reference State (1) by brush and weed control followed by natural reseeding or active replanting of native tree
T2A	-	The Cleared and Abandoned State (2) will transition to the Grazed Woodland State (3) by continued growth and spread of introduced and native tree species and closure of the overstory to shade out most shrubs, forbs, and grasses.
R3A	-	The Grazed Woodland State (3) may be restored to a facsimile of the Reference State (1) by brush and weed control followed by natural reseeding or active replanting of native trees.
R3B	-	The Grazed Woodland State (3) may be restored to the Cleared and Abandoned State (2) by clearing and abandoning the site, allowing lower-growing species that require sunlight to invade.

State 1 submodel, plant communities

1.1. Artocarpus - Faniok/Freycinetia

1.2. Tahitian Screwpine – Faniok/Freycinetia

1.1A	-	Community phase 1.1 may shift to phase 1.2 by damage from powerful storms.
1.2A	-	Community phase 1.2 reverts to phase 1.1 by regrowth of the original dominant species if given enough time between strong storm events. Browsing and grazing by introduced ungulates may inhibit this process by destruction of tree seedlings.

State 2 submodel, plant communities

2.1. Beach Sheoak/Lantana-Jack In The Bush/Mission Grass

State 3 submodel, plant communities

3.1. Small Philippine Acacia – Beach Sheoak/Guineagrass – Mission Grass

State 1
Reference State

The Reference State (1) has two community phases consisting of diverse native forest.

Community 1.1
Artocarpus - Faniok/Freycinetia

Dominant canopy species are artocarpus (Artocarpus mariannensis), Merrilliodendron megacarpum (locally known as faniok), grand devil’s-claws (Pisonia grandis), fig (Ficus prolixa), fern-leaved tamarind (Tristiropsis acutangula), Hernandia labyrinthica, Mammea odorata, Guettarda speciosa, Elaeocarpus joga, quandong (E. sphaericus), ifil (lntsia bijuga), Claoxylon marianum, and Hayun lagu (Serianthes nelsonii) (Amidon et al., 2017; Falanruw et al., 1989; Fosberg, 1960; Liu and Fischer, 2008; Stone, 1970; Wagner and Grether, 1948; Willsey et al., 2019). Some of the more common understory trees are Tahitian screwpine (Pandanus tectorius) and bakong (P. dubius), Aglaia mariannensis, Guamia mariannae, sea putat (Barringtonia asiatica), Melanolepis multiglandulosa, queen sago (Cycas circinalis), neisosperma (Neisosperma oppositifolia), Pipturus argenteus, umbrella catchbirdtree (Pisonia umbellifera), and Macaranga thompsonii (Amidon et al., 2017; Falanruw et al., 1989; Fosberg, 1960; Liu and Fischer, 2008; Stone, 1970; Wagner and Grether, 1948; Willsey et al., 2019). Piper guahamense is a common native forb. Climbers and vines include Freycinetia reineckei, Alyxia torresiana, and Flagellaria indica. Ferns are common (Amidon et al., 2017; Falanruw et al., 1989; Fosberg, 1960; Liu and Fischer, 2008; Stone, 1970; Wagner and Grether, 1948; Willsey et al., 2019).

Dominant plant species

artocarpus (Artocarpus mariannensis), tree
(Merrilliodendron megacarpum), tree
(Freycinetia reineckei), shrub

Community 1.2
Tahitian Screwpine – Faniok/Freycinetia

Storm damage to dominant overstory trees allows fast-growing or abundant subdominant species to temporarily become more abundant. Some typical species include Tahitian screwpine (Pandanus tectorius), sea hibiscus (Hibiscus tiliaceus), and Freycinetia reineckei. Some of the original dominant canopy species, such as faniok (Merrilliodendron megacarpum), may remain (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Willsey et al., 2019).

Dominant plant species

Tahitian screwpine (Pandanus tectorius), tree
(Merrilliodendron megacarpum), tree
(Freycinetia reineckei), shrub

Pathway 1.1A
Community 1.1 to 1.2

Community phase 1.1 may shift to phase 1.2 by damage from powerful storms.

Pathway 1.2A
Community 1.2 to 1.1

Community phase 1.2 reverts to phase 1.1 by regrowth of the original dominant species if given enough time between strong storm events. Browsing and grazing by introduced ungulates may inhibit this process by destruction of tree seedlings.

State 2
Cleared and Abandoned State

The Cleared and Abandoned State (2) consists of one community phase dominated by weedy or pioneer species. It may be grazed and browsed by introduced ungulates, but forage value is low.

Community 2.1
Beach Sheoak/Lantana-Jack In The Bush/Mission Grass

Common tree species in this community phase are the introduced small Philippine acacia (Acacia confusa) and the native pioneer species beach sheoak (Casuarina equisetifolia). Various grass species are common. Other species may be giant false sensitive plant (Mimosa diplotricha), scaly swordfern (Nephrolepis hirsutula), Philippine ground orchid (Spathoglottis plicata), monarch fern (Phymatosorus scolopendria), climbing hempvine (Mikania scandens), Jack in the bush (Chromolaena odorata), and Canadian horseweed (Conyza canadensis) (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Willsey et al., 2019). ). Guineagrass (Urochloa maxima) and mission grass (Pennisetum polystachion) persist in sunny openings (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Willsey et al., 2019).

Dominant plant species

beach sheoak (Casuarina equisetifolia), tree
lantana (Lantana camara), shrub
Jack in the bush (Chromolaena odorata), shrub
mission grass (Pennisetum polystachion), grass

State 3
Grazed Woodland State

The Grazed Woodland State (3) consists of a variable mix of introduced tree species, sometimes with a few native species, that form a dense forest. Small Philippine acacia (Acacia confusa) and beach sheoak (Casuarina equisetifolia) may dominant; other tree species will likely find their way onto a site. Cattle may forage in these forests, but carrying capacity is low (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Willsey et al., 2019).

Community 3.1
Small Philippine Acacia – Beach Sheoak/Guineagrass – Mission Grass

The introduced tree Small Philippine acacia (Acacia confusa) is often dominant, along with the native pioneer species beach sheoak (Casuarina equisetifolia). Depending on the history of the site, native species may constitute a variable component of the overstory. Common introduced tree species are royal poinciana (Delonix regia), woman’s tongue (Albizia lebbeck), and African tulip tree (Spathodea campanulata). Possible native species are Guamia mariannae, Melanolepis multiglandulosa, Cynometra (Cynometra ramiflora), fig (Ficus prolixa), and wild coffee (Psychotria spp). Invasive vines such as Jack in the bush (Chromolaena odorata) are likely to be present. Guineagrass (Urochloa maxima) and mission grass (Pennisetum polystachion) persist in sunny openings (CNMI SWARS Council, 2010; Donnegan et al., 2011; Liske-Clark, 2015; Willsey et al., 2019).

Dominant plant species

small Philippine acacia (Acacia confusa), tree
beach sheoak (Casuarina equisetifolia), tree
guineagrass (Urochloa maxima), grass
mission grass (Pennisetum polystachion), grass

Transition T1A
State 1 to 2

The Reference State (1) may transition to Cleared and Abandoned State (3) by clearing the forest, temporary cultivation of crops, abandonment, and invasion by mostly introduced species.

Restoration pathway R2A
State 2 to 1

The Cleared and Abandoned State (2) can be restored to a facsimile of Reference State (1) by brush and weed control followed by natural reseeding or active replanting of native trees.

Transition T2A
State 2 to 3

The Cleared and Abandoned State (2) will transition to the Grazed Woodland State (3) by continued growth and spread of introduced and native tree species and closure of the overstory to shade out most shrubs, forbs, and grasses.

Restoration pathway R3A
State 3 to 1

The Grazed Woodland State (3) may be restored to a facsimile of the Reference State (1) by brush and weed control followed by natural reseeding or active replanting of native trees.

Restoration pathway R3B
State 3 to 2

The Grazed Woodland State (3) may be restored to the Cleared and Abandoned State (2) by clearing and abandoning the site, allowing lower-growing species that require sunlight to invade.

Additional community tables

Supporting information

Other references

References for QX191X01X505 (Very Low Available Water Capacity Soils on Limestone Plateaus and Escarpments).

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., Hiserote, B. A. (2011). Commonwealth of the Northern Mariana Islands’ Forest resources, 2004. Resource. Bull. PNW-RB-261. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 40 p.

Falanruw, M. C., Cole, T. G., Ambacher, A. H. (1989). Vegetation survey of Rota, Tinian, and Saipan, Commonwealth of the Northern Mariana Islands. Resource. Bull. PSW-27. Berkeley, CA: Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture.

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.

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.

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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
Daniel Bowman
Amy Koch
Kendra Mosely
Sarah Quistberg
Brandan Brazee
Daniel Block
Jill Ficke-Beaton

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
Pamela Sablan, NRCS
Jay Doronilla, 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	06/16/2025
Approved by	Kendra Moseley
Approval date
Composition (Indicators 10 and 12) based on	Annual Production