Table 2.
Description and components of the Vegetation Multimetric Index and the indicators of stress (adapted from USEPA (2016b)
| Indicators | Description | Items included |
|---|---|---|
| Indicator of biological condition | ||
| Vegetation Multimetric Index (VMMI) | A four metric, national-scale VMMI was selected as having the best overall performance in assessing wetland condition based on a series of objective screening criteria | Floristic Quality Assessment Index, relative importance of native plants (combines relative cover and relative frequency of native plants), number of species tolerant to disturbance, relative cover of native monocots |
| Indicators of stress | ||
| Biological indicator | ||
| Nonnative plant indicator (NNPI) | Composed of three metrics that describe different avenues of potential impact to biological condition | Relative cover of nonnative species, richness of nonnative species, relative frequency of nonnative species |
| Physical indicators | ||
| Vegetation removal | Any field observation related to loss, removal, or damage of wetland vegetation | Gravel pit, oil drilling, gas wells, underground mine, forest clear cut, forest selective cut, tree canopy herbivory, shrub layer browsed, highly grazed grasses, recently burned forest, recently burned grassland, herbicide use, mowing/shrub cutting, pasture/hay, range |
| Vegetation replacement | Any field observation of altered vegetation within the site due to anthropogenic activities | Golf course, lawn/park, row crops in small amounts in the assessment area, row crops in the buffer, fallow field, nursery, orchard, tree plantation |
| Damming | Any field observation related to impounding or impeding water flow from or within the site | Dike/dam/road/RR bed, water level control structure, wall/riprap, dikes, berms, dams, railroad beds, sewer outfalls |
| Ditching | Any field observation related to draining water | Ditches, channelization, inlets/outlets, point source/pipe, irrigation, water supply, field tiling, standpipe outflow, corrugated pipe, box culvert, outflowing ditches |
| Hardening | Any field observation related to soil compaction, including activities and infrastructure that primarily result in soil hardening | Gravel road, two-lane road, four-lane road, parking lot/pavement, trails, soil compaction, off road vehicle damage, confined animal feeding, dairy, suburban residential, urban/multifamily, rural residential, impervious surface input, animal trampling, vehicle ruts, roads, concrete, asphalt |
| Filling/erosion | Any field observation related to soil erosion or deposition | Excavation/dredging, fill/spoil banks, freshly deposited sediment, soil loss/root exposure, soil erosion, irrigation, landfill, dumping, surface mine, recent sedimentation, excavation/dredging |
| Chemical indicators | ||
| Heavy Metal Index | Heavy metals with concentrations above background concentrations in soil samples | Antimony, cadmium, chromium, cobalt, copper, lead, nickel, silver, tin, tungsten, vanadium, zinc concentrations from the uppermost layer with soil chemistry |
| Soil phosphorus concentration | Soil phosphorus concentrations relative to reference sites | Measured phosphorus concentration from the uppermost layer within 10 cm of the soil surface with soil chemistry |