Effects of riparian forest removal on macroinvertebrate functional structure and production along tallgrass prairie streams.

Forest encroachment along tallgrass prairie streams is increasing, mainly due to fire suppression. Impacts of these riparian changes are poorly understood, but basal resources presumably shift from primarily autochthonous to allochthonous with increasing canopy cover, potentially altering macroinvertebrate functional structure and production. We removed riparian woody vegetation from two headwater prairie stream reaches and compared them to two naturally open reaches. Monthly macroinvertebrate samples were collected from each reach for one year before and after vegetation removal. Total production in removal reaches ranged from 8.9-10.2 g/m²/yr before removal and increased significantly to 13.4-14.5 g/m²/yr after removal. Scraper production in removal reaches was 2.8-3.9 g/m²/yr before removal and increased significantly to 6.0-8.7 g/m²/yr after removal, presumably due to shifts in basal resources. Total production in naturally open reaches ranged from 7.6-12.6 g/m²/yr before removal and decreased to 6.5-9.8 g/m²/yr after the removal. While woody vegetation removal altered macroinvertebrate production and functional structure, higher production in removal reaches compared to naturally open reaches suggests natural conditions were not restored one year after removal. However, macroinvertebrate community composition in removal reaches did become more similar to naturally open reaches after forest removal.  Results demonstrate how forest encroachment and removal (restoration) affect prairie streams.  This information can guide future management, restoration, and conservation of remaining grassland stream ecosystems.