Invertebrate community variation in seasonal forest wetlands: Implications for sampling and analyses

Using data sets from two separate studies, we assessed within-year variation in aquatic invertebrate communities in 31 seasonally flooded (seasonal) wetlands in aspen (Populus spp.) dominated forests in north central Minnesota. Principal components analysis (PCA) indicated that, in each case, three axes explained > 55% of variance in aquatic invertebrates, with the first axis strongly correlated with sampling date. Indicator species tests showed that this variation along axis I was largely due to shifts in abundance of crustaceans, Diptera and other insects, leeches, and other taxa. Temporal shifts in aquatic invertebrate community structure pose a major obstacle for ecological studies of aquatic invertebrates in seasonal forest wetlands and should receive more attention from investigators planning research in these and perhaps other wetland habitats.