Black willow thicket observed in the SW Hahamongna Basin
Black willow thickets made up the most dominant cover throughout the study area with some stands of tall trees (>30'). Growth was noted both in wide open flow areas with fine course sand soil as well as adjacent and creating canopies over deep meanders, usually opening before clay and compacted soils. Some wide space bare of vegetation is prevalent, especially where deposition seems to indicate strong periodic flows. Exotic species were generally absent or insignificant. Black willow species have a tendency to be dominant in more disturbed willow woodland below 1500' in seasonally flooded freshwater conditions with other willows including red willow (S. laevigata) and arroyo willow (S. lasiolepis) as well as cottonwoods.35 During the study other willow species were largely found in the wide northern sections adjacent and into mulefat scrub.
Mulefat thicket observed in the SW Hahamongna Basin
A mosaic of mulefat thickets was observed with black willow thickets, mulefat predominant in wide open flow areas with fine to very fine sandy soils. Emergent Populus fremontii were found in stands, as well as Salix laevigata and S. lasiolepis. Very minimal exotic species presence was with robust near monocultures in large patches observed at time of study, sometimes with wide space bare of vegetation between growth.
Wetland Indicator Status of Hahamongna Habitat
The USACE classifies plants that are found in a wetland with a likelihood of 0.99, 0.66, 0.5, 0.33, .01, as OBL, FACW, FAC, FACU, and UPL respectively. Species with common status were grouped together for calculation of indicator ratios.
The study area is characterized by dominant wetland indicator vegetation comprising more than 50% of cover surveyed at most locations throughout southwestern Hahamongna. This classifies most of the surveyed area as wetland by U.S. Army Corps of Engineers standards. Species were largely FAC and FACW in dominant black willow thickets with mosaic mulefat thickets in wide open flow areas and smartweed-cocklebur patches in deep meanders and clay soils. Groupings of OBL species were observed in low woodland openings and meanders. Additional FACW perennial pepperweed patch semi-natural stands were found on slopes and in elevated portions of the wash with UPL exotic associations. Upland coast live oak woodland and upland mustard series are found at the western and southwestern periphery of the study area.
Wetland Prevalance of Hahamongna Habitat
The prevalance of wetland vegetation coverage is calculated with a ratio of the sum of percent vegetation coverage and the sum of the percent coverage of each indicator multiplied by a coefficient determined by the US Army Corps of Engineers. This map shows areas of wetland vegetation prevalence in blue, and areas of upland vegetation prevelance in Red.
Wetland Dominance of Hahamongna Habitat
The requirement for the dominance test is such that over 50% of the dominant plant species found must be of indicator status FAC, FACW, or OBL. This map shows areas of wetland dominant vegetation in blue, and areas of upland dominant vegetation in Red.
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