Plant functional traits as indicator of the ecological condition of wetlands in the Grassland and Parkland of Alberta, Canada

The analysis of functional trait-habitat relationships has been used to measure the degree to which environmental factors influence the assembly of ecological communities. In the Parkland and Grassland natural regions of Alberta, wetlands are embedded in a matrix of human modified landscapes. The extent and effects of land uses on the condition of these wetlands and plant assemblages remains largely unknown. We used the physicochemical characteristics and plant functional traits collected in 322 wetlands as indicators of wetland condition. Plant functional traits included origin, life history, and habitat requirements. Physico-chemical characteristics at each wetland site were assessed and the intensity of land use quantified within a 250-meter buffer. Our analyses reveal that functional plant traits are impacted by surrounding land use intensity; the abundance of non-native (exotic), upland, and annual plants tend to increase with degree of agriculture. Wetlands in areas with abundant groundwater input (low isotopic oxygen-18 enrichment) tend to be associated with functional groups preferring stable hydrological conditions including perennials and upland species. This contrasts with wetlands with greater potential for evaporation which were shallower, had higher nutrient levels, and were positively associated with species tolerating higher levels of disturbances, such as annuals. Our study demonstrates how an understanding of plant functional trait-habitat relationship can provide a framework for linking the responses of taxonomically-unrelated plant species to the condition of wetlands, and ultimately be used as indicator of wetland condition.