Natural Resources
Conservation Service
Ecological site QX190X01X503
Sandy Loam or Loam
Last updated: 6/12/2025
Accessed: 09/28/2026
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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): 190X–Stratovolcanoes of the Mariana Islands
This MLRA occurs on the Northern Islands group of the Commonwealth of the Northern Mariana Islands. It consists of the islands of Pagan, Anatahan, Agrigan, Alamagan, Sarigan, and five smaller islands. The islands are largely unpopulated due to volcanic activity. The islands are cone-shaped stratovolcanoes covered with volcanic ash and cinder deposits on steep and very steep slopes. Agrigan has the highest elevation, ranging from sea level to 3,185 feet (970 meters). Average annual precipitation is about 80 inches (2,030 millimeters). Rainfall decreases northwards and increases slightly with elevation. Two-thirds of the precipitation falls between July and November. Average annual temperature is 79 degrees F (26 degrees C). The cooler dry season is between January and May. Trade winds blow from the northeast and east-northeast. Typhoons are frequent. Soils are Andisols, Inceptisols, or Entisols. The soil moisture regime is mostly ustic. The soil temperature regime is isohyperthermic. Abandoned coconut plantations occur on low elevation coastal sites. Areas above 330 feet (100 meters) are dominated by Pacific Island silvergrass or swordgrass (Miscanthus floridulus). Forest species are mixed tropical hardwoods. Large numbers of feral cows, pigs, and goats are on some of the islands (USDA-Natural Resources Conservation Service, 2006).
Classification relationships
This ecological site occurs within Major Land Resource Area (MLRA) 190 – Stratovolcanoes of the Mariana Islands.
Ecological site concept
This ecological site occurs on the islands of Agrigan, Alamagan, Pagan, and Sarigan in the Mariana Islands. It occurs on nearly level to very steep (0 to 100 percent) slopes of dissected footslopes, backslopes, alluvial fans, terraces, and lava plains on stratovolcanic islands at elevations ranging from 10 to 1,870 feet (3 to 570 meters) (Amidon et al., 2017; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2015; USDA-Natural Resources Conservation Service, 2001; Willsey et al., 2019; Soil Survey Staff, 2025).
Soils are moderately deep to very deep (21 to 72 inches or 53 to 183 centimeters), well drained Andisols (Typic Ustivitrands and Humic Ustivitrands) that formed in basaltic and andesitic volcanic ash and cinders. Soil temperature regimes are isohyperthermic; soil moisture regimes are ustic. Textures of the soil surface horizon range from ashy fine sandy loam to ashy loam. Average annual rainfall is about 80 inches (2,030 millimeters). Water runoff is low to very high; permeability is moderate or moderately rapid. Available water-holding capacity is moderate for most soils. Native and naturalized vegetation includes trees and short grasses (Amidon et al., 2017; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2015; USDA-Natural Resources Conservation Service, 2001; Willsey et al., 2019; Soil Survey Staff, 2025).Associated sites
QX190X01X001 Very Shallow
Soilis of QX190X01X001 (The Very Shallow Ecological Site) and QX190X01X503 (The Sandy Loam or Loam Ecological Site) occur on similar landscapes, soil parent materials, and slopes. The Sandy Loam or Loam Ecological Site generally occurs at lower elevations than the Very Shallow Ecological Site. The main differences between the two sites are that soils in the Sandy Loam or Loam Ecological Site have deeper effective rooting depths and higher available water holding capacity than soils in the Very Shallow Ecological Site. This enables the Sandy Loam or Loam Ecological Site to support forest vegetation and grasses rather than just the Pacific Island silvergrass (swordgrass) and other grasses that dominate the vegetation of the Very Shallow Ecological Site.
Similar sites
QX190X01X504 Silt Loam
Soils of QX190X01X504 (The Silt Loam Ecological Site) and QX190X01X503 (The Sand Loam or Loam Ecological Site) occur on similar landscapes, soil parent materials, and at similar elevation ranges. The Silt Loam Ecological soils have finer textures and greater available water holding capacity than the soils of this ecological site. Vegetative productivity should be somewhat higher in the Silt Loam Ecological Site than the Sandy Loam or Loam Ecological Site
Table 1. Dominant plant species
Tree (1) Pisonia grandis
(2) Ficus prolixaShrub Not specified
Herbaceous (1) Asplenium nidus
(2) Phymatosorus scolopendriaLegacy ID
F190XY503MP
Physiographic features
This ecological site occurs on dissected fans, terraces, footslopes, and backslopes, and cinder covered aa lava plains. The depth to the water table is greater than 72 inches (183 centimeters) (USDA-Natural Resources Conservation Service, 2001; Soil Survey Staff, 2025).
Table 2. Representative physiographic features
Landforms (1) Island > Stratovolcano
(2) Island > Caldera
(3) Island > Mountain slope
(4) Island > Lava plain
(5) Island > Alluvial fan
Runoff class Low to very high Flooding frequency None Ponding frequency None Elevation 10 – 1870 ft Slope 0 – 100 % Water table depth 72 in Aspect Aspect is not a significant factor Climatic features
Mean annual precipitation in this ecological site is about 80 inches (2,030 millimeters) and ranges from 70 to 90 inches (1,780 to 2,285 millimeters). Rainfall likely decreases northwards and slightly increases with elevation. Climate data are scarce for these remote islands. About two-thirds of the precipitation falls between July and November. Mean annual temperature is about 83 degrees F (28 degrees C) and ranges from 79 to 86 degrees F (26 to 30 degrees C). The cooler dry season is between January and May. It is enhanced by persistent trade winds from the northeast and east-northeast. Typhoons frequently pass close to the Northern Mariana Islands. Typhoons are less common in the north than on the more southerly Marianas islands that are severely impacted by large storms about once every 8 years on average. This area is freeze-free (Fosberg, 1960; USDA-Natural Resources Conservation Service, 2001).
Observations made on the Northern Stratovolcano Islands suggest that there are local climate differences among islands and at various elevations. Based on observations of frequent clouds and fog at the highest elevations and their apparent correlation with more luxuriant vegetation, fog drip can add significant moisture to the soil in some locations (Fosberg, 1960; USDA-Natural Resources Conservation Service, 2001).Table 3 Representative climatic features
Frost-free period (actual range) Freeze-free period (actual range) Precipitation total (actual range) 70-90 in Frost-free period (average) 370 days Freeze-free period (average) 370 days Precipitation total (average) 80 in ">Influencing water features
There are no water features in this ecological site.
Soil features
The soil components associated with this ecological site are Dekairu and Songsong which are classified as Andisols (Typic Ustivitrands and Humic Ustivitrands). Soil temperature regimes are isohyperthermic; soil moisture regimes are ustic. They are moderately deep to very deep (21 to 72 inches or 53 to 183 centimeters) and well drained. Available water holding capacity is low to moderate (2.6 to 6.1 inches) (Soil Survey Staff, 2025; USDA-Natural Resources Conservation Service, 2001).
Table 4. Representative soil features
Parent material (1) Basaltic volcanic ash
(2) Andesitic volcanic ash
(3) Cinders
Surface texture (1) Ashy fine sandy loam
(2) Ashy, gravelly loamy fine sand
(3) Ashy loam
Family particle size (1) Ashy
(2) Medial over ashy-pumiceous or ashy-skeletal
Drainage class Well drained Permeability class Moderate to moderately rapid Depth to restrictive layer 21 – 72 in Soil depth 21 – 72 in Surface fragment cover <=3" 0 – 40 % Surface fragment cover >3" Not specified Available water capacity
(0-40in)2.6 – 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)
(0-10in)5.5 – 7.9 Subsurface fragment volume <=3"
(0-40in)16 – 52 % Subsurface fragment volume >3"
(0-40in)Not specified Ecological dynamics
The main human disturbance is clearing land for cultivation and setting fires. Feral pigs, cattle, goats, and introduced deer are destructive to vegetation when their numbers are high (Willsey et al., 2019).
The main natural disturbance is strong storms that can damage or kill vegetation by high wind speeds. Volcanic activity on some islands can destroy vegetation by lava flows or ash deposition, setting succession back to the primary stage (Willsey et al., 2019).State and transition model
Custom diagramStandard diagram
Figure 1. State-and-Transition Model (STM) for the Sandy Loam or Loam Ecological Site (F190XY503MP)
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 textEcosystem states
States 1, 5 and 2 (additional transitions)
T1A - The Reference State (1) may transition to the Cleared and Abandoned State (4) by mechanical clearing of the land followed by invasion by introduced species and increase of native nondominant species. R2A - The Grassland State (2) can be restored to a facsimile of the Reference State (1) by suppressing grasses and replanting native trees. Protection from ungulates will likely be needed. T2A - The Grassland State (2) will transition to the Pioneer Tree-Invaded State (3) from Community Phase 2.2 as beach sheoak gradually forms denser stands and outcompetes other vegetation. R2B - The Grassland State (2) can be restored to the Farmed State (5) by removing grass species and cultivating crops or planting agroforest. R3B - The Pioneer Tree-Invaded State (3) can be restored to a facsimile of Reference State (1) by removal of beach sheoak followed by replanting of a variety of native tree species commonly found in State 1. R3A - The Pioneer Tree-Invaded State (3) may be restored to the Grassland State (2) by human-caused fire. R3C - The Pioneer Tree-Invaded State (3) can be restored to the Farmed State (5) by clearing the land and cultivating crops or planting agroforest. R4A - The Cleared and Abandoned State (4) may be restored to a facsimile of the Reference State (1) by brush and weed control followed by replenishing native tree species and numbers. T4B - The Cleared and Abandoned State (4) may transition to the Grassland State (2) if fire clears a site before development of closed forest with little understory and where Pacific Island silvergrass is either still present or seed sources are nearby. T4A - The Cleared and Abandoned State (4) may transition to the Pioneer Tree-Invaded State (3) by if few or no seed sources for trees other than beach sheoak are near the site during the temporary stage dominated by grasses, forbs, and shrubs. R4B - The Cleared and Abandoned State (4) may be restored to the Farmed State (5) by clearing the site, followed by cultivation or planting agroforest. R5A - The Farmed State (5) may be restored to a facsimile of the Reference State (1) by weed control followed by replanting of native trees. T5A - The Farmed State (5) transitions to the Cleared and Abandoned State (4) when the site is abandoned in the presence of tree seed sources. State 1 submodel, plant communities
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. State 2 submodel, plant communities
2.1A - Community phase 2.1 will shift to Community Phase 2.2 with invasion by native beach sheoak (Casuarina equisetifolia). P2.2A - Community phase 2.2 will revert to Community Phase 2.1 with human-caused fire, which kills beach sheoak. State 3 submodel, plant communities
State 4 submodel, plant communities
State 5 submodel, plant communities
State 1
Reference StateThe Reference State (1) has two community phases consisting of native forest. Few if any intact examples remain of undisturbed forest in this ecological site. Dominant canopy species can vary by island and region of island, making this forest type hard to characterize by dominant or even characteristic species. The undergrowth in this forest is usually sparse and perhaps not very flammable (Amidon et al., 2017; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2015; Willsey et al, 2019).
Community 1.1
Grand Devil’s Claws – Fig/Hawai'i Birdnest Fern - Monarch Fern/FreycinetiaDominant trees include, among others, Aglaia mariannensis, Elaeocarpus joga, grand devil’s claws (Pisonia grandis), fig (Ficus prolixa), fig (F. tinctoria), ifil (lntsia bijuga), Tahitian screwpine (Pandanus tectorius), bakong (P. dubius), Guamia mariannae, neisosperma (Neisosperma oppositifolia), tropical almond (Terminalia catappa), Oriental trema (Trema orientalis), and tiger’s claw (Erythrina variegata var. orientalis) (Amidon et al., 2017; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2015; Willsey et al, 2019). Freycinetia (Freycinetia reineckei) is a small tree or shrub which occupies the midstory of this ecological site.
The understory may include monarch fern (Phymatosorus scolopendria), giant brake (Pteris tripartita), and Hawai'i birdnest fern (Asplenium nidus) (Amidon et al., 2017; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2015; Willsey et al, 2019).Dominant plant species
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grand devil's-claws (Pisonia grandis), tree
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fig (Ficus prolixa), tree
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Hawai'I birdnest fern (Asplenium nidus), other herbaceous
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monarch fern (Phymatosorus scolopendria), other herbaceous
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(Freycinetia reineckei), other herbaceous
Community 1.2
Sea Hibiscus – Aglaia/Monarch Fern – Giant Brake/FreycinetiaStorm damage to dominant overstory trees allows fast-growing or abundant subdominant species to temporarily become more abundant. Some typical species include Aglaia mariannensis, Tahitian screwpine (Pandanus tiliaceus), sea hibiscus (Hibiscus tiliaceus), grand devil’s claws (Pisonia grandis), yellow-boxwood (Planchonella obovata), and beach sheoak (Casuarina equisetifolia) (Amidon et al., 2017; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2105; Willsey et al, 2019).
Freycinetia (Freycinetia reineckei) occurs in the midstory here as a small tree or shrub. Understory species include monarch fern (Phymatosorus scolopendria), and giant brake (Pteris tripartita).Dominant plant species
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sea hibiscus (Hibiscus tiliaceus), tree
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(Aglaia mariannensis), tree
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monarch fern (Phymatosorus scolopendria), other herbaceous
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giant brake (Pteris tripartita), other herbaceous
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(Freycinetia reineckei), other herbaceous
Pathway 1.1A
Community 1.1 to 1.2Community phase 1.1 may shift to phase 1.2 by damage from powerful storms.
Pathway 1.2A
Community 1.2 to 1.1Community phase 1.2 reverts to phase 1.1 by regrowth of the original dominant species if given enough time between strong storm events.
State 2
Grassland StateThe Grassland State (2) consists of two community phases consisting mostly of native grass species.
Community 2.1
Pacific Island Silvergrass (swordgrass) – DimeriaPacific Island silvergrass or swordgrass (Micranthus floridulus) is the main grass species. It provides little forage for animals. Other possible grass species are dimeria (Dimeria chloridiformis), which is a native, golden false beardgrass (Chrysopogon aciculatus), which may be native or an early human introduction, southern crabgrass (Digitaria ciliaris) and sourgrass (D. insularis), both of which are introduced, and East Indian crabgrass (D. setigera), which may be native or an early introduction. Native ferns may include midsorus fern (Blechnum orientale), swordfern (Nephrolepis spp.), and Old World forkedfern (Dicranopteris linearis) (Amidon et al., 2017; Amidon et al., 2019; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2105; Willsey et al, 2019).
Dominant plant species
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(Dimeria chloridiformis), shrub
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Pacific Island silvergrass (Miscanthus floridulus), grass
Community 2.2
Beach Sheoak/Pacific Island Silvergrass – DimeriaPacific Island silvergrass or swordgrass (Miscanthus floridulus), other grasses, and ferns still dominate this community phase. However, beach sheoak (Casuarina equisetifolia), the primary native pioneer tree species in this ecological site, is beginning to spread throughout the community (Amidon et al., 2017; Amidon et al., 2019; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2105; Willsey et al, 2019).
Dominant plant species
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beach sheoak (Casuarina equisetifolia), tree
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Pacific Island silvergrass (Miscanthus floridulus), grass
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(Dimeria chloridiformis), grass
Pathway 2.1A
Community 2.1 to 2.2Community phase 2.1 will shift to Community Phase 2.2 with invasion by native beach sheoak (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=CAEQ" target="_blank" title="Open in plants.usda.gov"><i>Casuarina equisetifolia</i></a>).
Pathway P2.2A
Community 2.2 to 2.1Community phase 2.2 will revert to Community Phase 2.1 with human-caused fire, which kills beach sheoak.
State 3
Pioneer Tree-Invaded StateThe Pioneer Tree-Invaded State (3) consists of one community phase dominated by beach sheoak (Casuarina equisetifolia), the primary native pioneer tree species.
Community 3.1
Beach SheoakThis community phase is dominated by nitrogen-fixing beach sheoak (Casuarina equisetifolia), which outcompetes lower vegetation and creates a layer of litter that contains allelopathic compounds. It gradually forms stands that exclude most other vegetation (Amidon et al., 2017; Amidon et al., 2019; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2015; Willsey et al, 2019).
Dominant plant species
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beach sheoak (Casuarina equisetifolia), tree
State 4
Cleared and Abandoned StateThe Cleared and Abandoned State (4) consists of one community phase with a variable mix of native and introduced tree species. Some grasses and light-requiring shrubs are likely to persist until they are shaded out by canopy closure.
Community 4.1
Beach Sheoak – Tahitian Screwpine/Bellyache Bush/Pacific Island SilvergrassThis phase will be temporarily dominated by Pacific Island silvergrass or swordgrass (Miscanthus floridulus) and other grasses, forbs, and shrubs until the tree canopy develops. Common introduced tree species such as small Philippine acacia (Acacia confusa), woman’s tongue (Albizia lebbeck), African tulip tree (Spathodea campanulata), and monkeypod (Pithecellobium dulce) may invade sites. Some possible native species to occur here are beach shoak (Casuarina equisetifolia), Tahitian screwpine (Pandanus tectorius), sea hibiscus (Hibiscus tiliaceus), fig (Ficus tinctoria and F. prolixa), Aglaia mariannensis, coconut (Cocos nucifera), Guamia mariannae, Melanolepis multiglandulosa, and grand devil’s claws (Pisonia grandis). Bellyache bush (Jathropha gossypiifolia) shrubs may be present. The understory may include monarch fern (Phymatosorus scolopendria), giant brake (Pteris tripartita), and Hawai'i birdnest fern (Asplenium nidus).
Dominant plant species
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beach sheoak (Casuarina equisetifolia), tree
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Tahitian screwpine (Pandanus tectorius), tree
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bellyache bush (Jatropha gossypiifolia), shrub
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Pacific Island silvergrass (Miscanthus floridulus), grass
State 5
Farmed StateThis state consists of one community phase that is used for cultivated agriculture or agroforestry.
Community 5.1
Various Crops or AgroforestryPossible agroforestry tree species are coconut palm (Cocos nucifera), tree breadfruit (Artocarpus altilis), tree mango (Mangifera indica), papaya (Carica papaya), banana (Musa spp.), and citrus (Citrus spp.) (Amidon et al., 2017; Amidon et al., 2019; Carlisle et al., 2001; Fosberg, 1960; Kessler, 2011; Liske-Clark, 2015; Willsey et al, 2019).
Dominant plant species
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coconut palm (Cocos nucifera), tree
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breadfruit (Artocarpus altilis), tree
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mango (Mangifera indica), tree
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papaya (Carica papaya), tree
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citrus (Citrus), tree
Transition T1A
State 1 to 4The Reference State (1) may transition to the Cleared and Abandoned State (4) by mechanical clearing of the land followed by invasion by introduced species and increase of native nondominant species.
Restoration pathway R2A
State 2 to 1The Grassland State (2) can be restored to a facsimile of the Reference State (1) by suppressing grasses and replanting native trees. Protection from ungulates will likely be needed.
Transition T2A
State 2 to 3The Grassland State (2) will transition to the Pioneer Tree-Invaded State (3) from Community Phase 2.2 as beach sheoak gradually forms denser stands and outcompetes other vegetation.
Transition R2B
State 2 to 5The Grassland State (2) can be restored to the Farmed State (5) by removing grass species and cultivating crops or planting agroforest.
Restoration pathway R3B
State 3 to 1The Pioneer Tree-Invaded State (3) can be restored to a facsimile of Reference State (1) by removal of beach sheoak followed by replanting of a variety of native tree species commonly found in State 1.
Restoration pathway R3A
State 3 to 2The Pioneer Tree-Invaded State (3) may be restored to the Grassland State (2) by human-caused fire.
Restoration pathway R3C
State 3 to 5The Pioneer Tree-Invaded State (3) can be restored to the Farmed State (5) by clearing the land and cultivating crops or planting agroforest.
Restoration pathway R4A
State 4 to 1The Cleared and Abandoned State (4) may be restored to a facsimile of the Reference State (1) by brush and weed control followed by replenishing native tree species and numbers.
Transition T4B
State 4 to 2The Cleared and Abandoned State (4) may transition to the Grassland State (2) if fire clears a site before development of closed forest with little understory and where Pacific Island silvergrass is either still present or seed sources are nearby.
Transition T4A
State 4 to 3The Cleared and Abandoned State (4) may transition to the Pioneer Tree-Invaded State (3) by if few or no seed sources for trees other than beach sheoak are near the site during the temporary stage dominated by grasses, forbs, and shrubs.
Restoration pathway R4B
State 4 to 5The Cleared and Abandoned State (4) may be restored to the Farmed State (5) by clearing the site, followed by cultivation or planting agroforest.
Restoration pathway R5A
State 5 to 1The Farmed State (5) may be restored to a facsimile of the Reference State (1) by weed control followed by replanting of native trees.
Restoration pathway T5A
State 5 to 4The Farmed State (5) transitions to the Cleared and Abandoned State (4) when the site is abandoned in the presence of tree seed sources.
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 (%) Table 11. Community 5.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Supporting information
Other references
References for the Sandy Loam or Loam Ecological Site (QX190X01X503)
Amidon, F., Brunson, C., Flores, J., Frager, R., Galsim, F., Miller, S. E., Pe`a, R., and Reeves, M. K. (2019). Savannas of the Mariana Islands Archipelago. Encyclopedia of the World's Biomes. Elsevier Inc. Https://doi.org/10.1016/B978-0-12-409548-9.11986-4
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.
Carlisle, S., Parks, G., Paris, K., and Monroe, K. (2001). Soil Survey of the Islands of Agrihan, Alamagan, Anatahan, Pagan, and Sarigan, Commonwealth of the Northern Marianas. Soil Survey Horizons 42:3.
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.
Kessler, C. C. (2011). Invasive species removal and ecosystem recovery in the Mariana Islands; challenges and outcomes on Sarigan and Anatahan. IN: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011.
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.
Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Official Soil Series Descriptions. Available online. Accessed [04/28/2025].
USDA-NRCS. (2006). Major Land Resource Regions. USDA Agriculture Handbook 296. http://soils.usda.gov/MLRAExplorer
USDA-Natural Resources Conservation Service. (2001). Soil Survey of the Northern Volcanic Islands, Commonwealth of the Northern Marianas. Web Soil Survey, https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx
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\B978-0-12-409548-9.12012-3Contributors
David Clausnitzer PhD
John Proctor
Ann Tan
Daniel Bowman
Amy Koch
Kendra Moseley
Sarah Quistberg
Jill Ficke-Beaton
Daniel Block
Brendan BrazeeApproval
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 Sollyann Takai, NRCS Jay Doronila, NRCS Carolyn Auweloa, 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 09/28/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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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:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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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:
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Perennial plant reproductive capability:
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