Print Report
G429 Marsilea villosa Vernal Pool Group
Type Concept Sentence: This rare, intermittently wet fern wetland is now restricted to O`ahu and Moloka`i, and is characterized by the dominance of the federally endangered endemic fern Marsilea villosa.
Common (Translated Scientific) Name: `Ihi`ihlauakea Vernal Pool Group
Colloquial Name: Hawaiian Vernal Pool
Hierarchy Level: Group
Type Concept: This rare, intermittently wet fern wetland is now restricted to O`ahu and Moloka`i, and is characterized by the dominance of the federally endangered endemic fern Marsilea villosa. On the seasonal floodplain in Lualualei Valley, O`ahu, scattered depressions support Marsilea mats under scattered Prosopis pallida and among Sida fallax. At `Ihi`ihilauâkea Crater, O`ahu, the crater floor is thickly covered with Marsilea when seasonal rains saturate the soil, sometimes submerging the habitat. During dry periods the fern becomes a dormant rhizomatous mat, and the area appears to be a weedy dryland of grasses and forbs, including Amaranthus spinosus, Chloris barbata, Cynodon dactylon, Setaria verticillata, Merremia aegyptia, and Xanthium strumarium. Sexual reproduction of Marsilea may occur as infrequently as once every ten or more years, due to the infrequency of sufficiently heavy rains in lowland areas. This rare, intermittently wet fern wetland develops in lowland vernal pools and areas that get flooded periodically. It occurs in shallow depressions in clay soil, cinder craters, or lithified sand dunes overlain with alluvial clay common in dry areas of most islands where winter rains create seasonal pools at elevations between 424 and 1032 m (1391-3385 feet). On Moloka`i, it occurs in rocky areas that never hold standing water but get flushed out annually or less often. Historic populations on O`ahu were destroyed by drainage of ponding areas, habitat degradation, competition from exotic plants, off-road vehicle use, and development.
Diagnostic Characteristics: The Hawaiian endemic fern Marsilea villosa is the indicator and dominant species for this group.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Currently sites are characterized by weedy, non-native species until seasonal rain saturate soil and the fern Marsilea villosa emerges from a dormant rhizomatous mat and dominates the area.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: This Hawaiian vernal pool group is characterized by dominance of endemic fern Marsilea villosa. During dry periods the fern becomes a dormant rhizomatous mat, and the area appears to be a weedy, non-native dryland of grasses and forbs, including Amaranthus spinosus, Chloris barbata, Cynodon dactylon, Setaria verticillata, Merremia aegyptia, and Xanthium strumarium.
Dynamics: No Data Available
Environmental Description: This rare, intermittently wet fern wetland is now restricted to O`ahu on the seasonal floodplain in Lualualei Valley and at `Ihi`ihilauâkea Crater, and on rocky areas on Moloka`i that never hold standing water but get flushed out annually or less often. Elevation ranges between 424 and 1032 m (1391-3385 feet). It typically occurs in shallow depressions with fine-textured soil where winter rains create seasonal pools At `Ihi`ihilauâkea Crater seasonal rains saturate the soil, sometimes submerging the habitat. Historic populations on O`ahu were destroyed by drainage of ponding areas, habitat degradation, competition from exotic plants, off-road vehicle use, and development.
Climate: Climate is tropical with seasonal precipitation (100-500 mm). Moisture zones for Lualualei Valley and at `Ihi`ihilauâkea Crater are very dry (Zone 2) of the 7 Moisture Zones developed for the Hawaiian Islands by Price et al. (2007).
Soil/substrate/hydrology: Substrates are commonly clay soils, either cinder deposits or lithified sand dunes overlain with alluvial clay.
Climate: Climate is tropical with seasonal precipitation (100-500 mm). Moisture zones for Lualualei Valley and at `Ihi`ihilauâkea Crater are very dry (Zone 2) of the 7 Moisture Zones developed for the Hawaiian Islands by Price et al. (2007).
Soil/substrate/hydrology: Substrates are commonly clay soils, either cinder deposits or lithified sand dunes overlain with alluvial clay.
Geographic Range: Remnant stands of this intermittently flooded wet fern wetland are restricted to O`ahu and Moloka`i.
Nations: US
States/Provinces: HI
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.860729
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 2 Shrub & Herb Vegetation Class | C02 | 2 |
| Subclass | 2.C Shrub & Herb Wetland Subclass | S44 | 2.C |
| Formation | 2.C.3 Tropical Freshwater Marsh, Wet Meadow & Shrubland Formation | F030 | 2.C.3 |
| Division | 2.C.3.Ob Polynesian-Eastern Melanesian Freshwater Marsh Division | D019 | 2.C.3.Ob |
| Macrogroup | 2.C.3.Ob.2 Polynesian Freshwater Marsh Macrogroup | M042 | 2.C.3.Ob.2 |
| Group | 2.C.3.Ob.2.b `Ihi`ihlauakea Vernal Pool Group | G429 | 2.C.3.Ob.2.b |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: No Data Available
- Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
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- USFWS [U.S. Fish and Wildlife Service]. 2003. Endangered and Threatened wildlife and plants: Final designations or nondesignations of Critical Habitat for 101 plant species from the Island of Oahu, HI. Federal Register 68 (116): 35949-35998.
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