Using multiple taxa and wetland classification schemes for enhanced detection of biological response signatures to human impairment

Abstract

Wetland indices of biological integrity (IBIs) are a common component in monitoring the wetland water resources as required by the United States’ Clean Water Act (CWA). The effectiveness of an IBI to monitor disturbance is dependent on the metrics being consistently responsive to measures of human disturbance within a described classification category. We present IBIs designed for two types of commonly used wetland classification systems – the hydrogeomorphic (HGM) and the National Wetlands Inventory (NWI). The metrics making up the IBIs were derived from anuran, avian, macroinvertebrate, and vegetation communities; each representing increasing levels of resources associated with gathering the necessary data. Knowing which communities’ data best corresponds to impairment can maximize limited wetland monitoring resources, especially if the response differs based on the wetland vegetation type NWI or HGM position on the landscape. By combining these two classification schemes together, to better define a wetland’s form and context on the landscape, more of the variability in community metrics are explained by human impairment. Moreover, when multiple taxa are used within a single wetland classification scheme, the response of the multi-taxa community IBI to the human disturbance gradient is often more sensitive than one-taxa group alone. This approach, a combination of taxa, in hybrid 2-system classification schemes, creates additional utility in measuring the effectiveness of wetland assessments and, or restoration success.