|
FAC neutral Test
Compiling a list of dominant plant species can aid in
determining whether as site is classified as a hydrophytic
community. The FAC-neutral test can be used to provide a
secondary indicator. A positive secondary indicator of hydrology
occurs when more of the dominant plant species have a wetland
indicator category that is wetter than FAC. (For an
explanation of wetland indicator click
 here).
The FAC-neutral test considers
Facultative species (FAC-,
FAC, or FAC+) as neutral and does not utilize them. Rather,
the abundance of
Obligate (OBL),
and
Facultative Wetland
(FACW, FACW+, and FACW-) species are
weighed against the abundance of
Upland and
Facultative Upland
(FACU-, FACU, and FACU+)
species (OBL + FACW species > FACU + UPL species) to
determine whether the vegetation meets the FAC-neutral
test.”
To view the wetland indicator status of plants by genus,
family, and/or wetland region, click
here.
|
Plant species may be used as a
secondary indicator when determining the wetland status of
an area. The FAC-neutral test reflects the range of
estimated probabilities (expressed as a frequency of
occurrence) of a species occurring in wetlands versus
non-wetland across the entire distribution of the species. A
frequency, for example, of 67%-99% (Facultative Wetland)
means that 67%-99% of sample plots containing the species
would be
wetland plots. When two indicators are given, they reflect the
range from the lowest to the highest frequency of occurrence
in wetlands across the regions in which the species is
found. A positive (+) or negative (-) sign was used with the
Facultative Indicator categories to more specifically define
the regional frequency of occurrence in wetlands. The
positive sign indicates a frequency toward the higher end of
the category (more frequently found in wetlands), and a
negative sign indicates a frequency toward the lower end of
the category (less frequently found in wetlands). A question
mark (?) following a National Indicator denotes a tentative
assignment based on the botanical literature and not
confirmed by regional review.
Regional Indicators express the estimated probability
(likelihood) of a species occurring in wetlands versus
non-wetlands in a particular region. An asterisk (*) following a regional Indicator
identifies tentative assignments based on limited
information from which to determine the indicator status.
|
