|Shields Jr, Fletcher|
Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 15, 1995
Publication Date: N/A
Interpretive Summary: Streams in many agricultural watersheds have been destabilized by historical management practices like deforestation, channelization, and a lack of on-farm conservation measures. Cost-effective strategies to restore stream channel stability and ecological resources are needed, but scientific studies of restoration projects, particularly those in unstable, warmwater streams, are scarce. Two small streams in northwest Mississippi undergoing accelerated erosion were stabilized using different structural and vegetative measures, and physical and biological response was measured for two to three years. Results indicate that even minor increases in pool habitat can produce desirable shifts in fish communities, but without a stabilization plan that specifically considers habitat restoration, improvements in biological resources will be limited and possibly not long lived.
Technical Abstract: Many stream ecosystems are severely limited by damaged physical habitat. Cost-effective strategies are needed to address erosion problems and restore stream corridor habitats. Detailed studies of restoration outcomes are rare. Herein we present a case study of two small streams (watershed size = 12 and 14 km**2) damaged by channel straightening and incision. One stream was stabilized using a low drop grade control structure and dormant willow post planting, while the other was treated with a stone weir, stone toe bank protection, and willow sprout planting. Effects of restoration were monitored by collecting physical and biological data for one to two years before restoration and two to three years afterward. Following construction, channel planforms were stable, but up to 1 m of deposition and erosion occurred along the thalweg profile. Willow planting was not successful, so canopy, bank vegetation and woody debris density were unchanged. Pool habitat area increased from less than 5% to more than 30%. Fish species richness was unchanged, but species composition shifted away from cyprinids that occur in shallow, sandy runs toward pool-dwelling types (catostomids and centrarchids). Response to restoration was more modest than for two nearby restoration projects. Potential causes include less ambitious restoration design, greater initial degradation, and isolation from less-degraded sites which could serve as sources of colonists