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 varied slightly between open and closed canopy reaches during the spring and summer, but in the winter without any leaf cover, open canopy reaches had more chlorophyll than closed canopy. Fully lighted areas had luxurious growth of filamentous algae. The ratio of the dry weight of the filaments to the amount of chlorophyll in the reach revealed a strong increase in filamentous primary producers in open reaches. Closed canopied reaches had more leaves and wood which alters microhabitats available for micro and macro organisms and alters the availability of carbon.