Adult insect assemblages as a conservation planning tool

Summary

Our study found differences in insect populations collected from three regions in Texas. We showed that three to four light trap samples taken on consecutive nights are sufficient to capture the pooled insect diversity of the wetlands we studied. While we were able to show differences across these broad regions using insects identified to the order level, we found no patterns when we examined differences between specific wetland types, using the same taxonomie level. Within a single region, however, we were able to use insects from one order (Tri- choptera), identified to the family level, to discriminate between different wetland types: Trichopteran family-level cumulative diversity measures were significantly different between sites classified by abiotic ecosystem properties (geographic location, hydrology) and by biotic ecosystem properties (vegetation type).

Our study focuses on the responses of assemblages rather than individuals. We chose aquatic insects as potential indicators because insects are rarely, if ever, directly manipulated by ecosystem managers. Insect data are collected and analyzed using well-known methodologies that do not rely on professional judgment, as in the case of some assessment techniques (i.e. HGM, HEP, WET). Our method looks at the response of an entire suite of organisms, some with very strict requirements or ecological tolerances that are quick to respond to changes in their environment. We recognize that there are situations where it is entirely appropriate to measure effects on a specific target species. However, if the goal is to manage functions rather than species, then a single species approach may not be appropriate.