Macroinvertebrate Communities Vary With Surface Water Permanence but Not Land Management in a Tallgrass Prairie Stream Network.

Native tallgrass prairies once covered much of the North American Great Plains but have largely been converted to agriculture and other land uses. The remaining areas of native prairie thus serve as critical benchmarks for understanding global change. Konza Prairie Biological Station (KPBS) is located within one of the largest remaining areas of native tallgrass prairie. Streams within the biological station are characterized by hydrologic extremes, including prolonged periods of drying in some reaches. Additionally, experimental grazing and prescribed burn treatments vary among sub-watersheds. To examine the effects of surface water permanence, grazing, and prescribed burns, we collected stream aquatic macroinvertebrate samples from 10 sites annually for 2 years. We targeted both benthic and edge aquatic macroinvertebrate communities in our sampling. We also used continuous logger data from each site to classify sites as one of three stream types: short-flowing, long-flowing, or perennial. We expected aquatic macroinvertebrate richness and diversity to increase with surface water permanence and to be greater at sites located in sub-watersheds where no grazing or prescribed burns occur. Our analysis showed that benthic and edge macroinvertebrate richness varied with stream type and sampling year. Richness tended to increase with surface water permanence and was greater in the first year of sampling. The composition of benthic and edge communities also varied with stream type and sampling year. Macroinvertebrate diversity did not vary with any of the variables considered. Additionally, we found no impact of grazing or burn regime on aquatic macroinvertebrate community richness, diversity, or composition. In many parts of the Great Plains, streamflow is not sufficiently protected, and the spatial and temporal extent of stream drying is expanding. Our work underscores the importance of protecting streamflow in the Great Plains and that doing so is likely to benefit stream ecosystems even in the presence of potential co-occurring disturbances.