Impact of woody vegetation removal on prairie streams

Woody vegetation encroachment threatens remaining native tallgrass prairie streams.  Kings Creek is a prairie stream that was historically a mostly open canopy stream with little surrounding woody vegetation.  Many reaches in Kings Creek have been subjected to woody expansion and now have a closed canopy.  Closed canopy reaches receive less sunlight for primary producers and receive more leaf and wood material.  Woody vegetation was removed from two 35 m reaches in order to determine the impact of woody expansion on stream ecosystem structure and function.  We measured whole-stream metabolism in reaches with naturally open and closed canopies and in the vegetation removal reaches.  Measurements were made seasonally, pre and post removal.  The closed canopy reaches were 60-85% closed and the naturally open canopy reaches were 6-17% closed.  The removal reaches went from 60-80% closed to about 5% closed.  Daily gross primary production was at least 3 times greater in open canopy reaches than in closed canopy.  Heterotrophic respiration was not influenced by canopy cover.  Chlorophyll a was significantly greater in open canopied reaches than under closed canopy, even in winter without leaf cover.  Fully lighted areas had luxurious growth of filamentous algae.