CHEMISTRY AND MICROBIAL ACTIVITY OF FOREST AND PASTURE RIPARIAN-ZONE SOILS ALONG 3 PACIFIC-NORTHWEST STREAMS

Throughout the United States, agricultural practices are responsible f or large quantities of nutrients entering lakes and streams. Previous studies have shown that forested riparian areas can filter nutrients f rom surface runoff and groundwater that may potentially contaminate la kes and streams. This study examined seasonal differences in soil chem istry and soil microorganisms in paired mixed-forest riparian and past ure systems, the aim being to gain understanding of the sequestering o f N and P. The forest soils retained higher levels of organic C and N, mineralizable N, extractable P, and fungal biomass, and had higher re spiration rates than pasture soils. These findings suggest that forest ed riparian zones have a greater capacity than pasture soils to seques ter C and retain nutrients. In past studies, fungal biomass has been s hown to be less than bacterial biomass in grassland soils, but in this study, fungal biomass was greater than bacterial biomass throughout t he year in both forest and pasture soils.