Responses of macroinvertebrate communities to 4 years of deer exclusion in first- and second-order streams.

We compared hydrological environments and macroinvertebrate communities in 1st- and 2nd- order streams between a deer-excluded catchment (EC) and a control catchment (CC) to test effects of deerinduced hillslope soil erosion and sedimentation on macroinvertebrates. Overland flow contribution to the streams was greater in CC than in EC, and substrate in 1st-order streams contained more fine sediment in CC than in EC, whereas fine sediment in substrate in 2nd-order streams was similar between catchments. Macroinvertebrate community structure in 2nd-order streams was similar between catchments, but community structure in 1st-order streams differed between catchments. In 2nd-order streams, grazer and predator taxa predominated in both catchments, whereas in 1st-order streams, a clinger taxon predominated in EC and a burrower taxon predominated in CC. Diversity of macroinvertebrates in 1st- order streams was 1.14× higher in EC than in CC. We suggest that effects of deer on macroinvertebrates were less apparent in 2nd- than in 1st-order streams because fine sediments did not accumulate in 2nd-order streams exposed to deer browsing. Our results suggest that effects of sediment addition caused by deer browsing depends on the hydrogeomorphic properties of headwater streams. [ABSTRACT FROM AUTHOR]