Standard Operating Procedures (6.2): Terrestrial Invertebrates

Terrestrial invertebrates are a vital component of wetland food webs and are indicators of the overall health of a system (Zedler 2001).

The primary purpose of this sampling method is to document aerial and epigeal (above soil surface) arthropod productivity (as biomass per unit area, or biomass per day) for each habitat or area by extrapolation from enumerated arthropods via length-fresh weight regressions. Taxa should be assessed in the pitfall traps by sorting to a higher taxonomic classification (e.g., order) or recognizable taxonomic units (RTUs) to facilitate the use of student and volunteer (non-professional taxonomic identification) assistance, but they can also be sorted to lower taxa by taxonomists. To meet previously identified concerns of local resource managers, these sampling methods include specific steps/elements to minimize any impacts upon non-target taxa (e.g., birds encountering sticky traps, coyotes ingesting pitfall traps). Sticky traps are routinely surrounded by tomato cages to deter birds from contacting the adhesive trap surface and have no statistical effect on the arthropod biomass accumulated by those sticky traps (Anderson 2010); similarly, plastic covers suspended just above pitfall traps deter ancillary catch of herpetofauna and small mammals in pitfall traps.

Prepared for the United States Environmental Protection Agency.