Relationship among Plant Functional Groups, Soil, and Moisture as Basis for Wetland Conservation

Abstract

This study characterized the relationship between plant species, soil, and moisture dynamics in the Willamette Valley (Oregon, USA) to obtain a base framework for wetland conservation and restoration. We identified 24 dominant plant species, including the exotic invasive Dipsacus fullonum, distributed throughout the wetland. Plant community analysis indicated that (1) soil moisture during the dry season (August to October) and (2) soil bulk density were the major abiotic drivers of plant community structure. Water potential measurements confirmed the community analysis. Juncus (rush) species appeared to be more tolerant to drought than other typical wetland species. Therefore, dryer conditions due to climate change or water diversion may favor rushes’ persistence. We also found that the dominance of D. fullonum may also negatively affect the native plant species’ survival, which highlights the need for proper management practices. To prevent further vegetation deterioration in sensitive wetland areas, we recommend avoiding hydric diversions to maintain the water supply, exploring manners of controlling invasive species, and preventing livestock grazing. The results of this study contribute to foundational and practical knowledge concerning the influence of soil conditions and moisture availability on the physiological response and distribution of wetland plant species that is required for conservation and management.