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Modifying erosion control structures for ecological benefits.

Edge-of-field water control structures known as drop pipes are widely employed conservation practices used to control gully erosion along incised streams in northwestern Mississippi (Shields et al. 2002). These structures consist of earthen embankments placed across eroding riparian gullies and use corrugated metal standpipes to provide drainage from field to stream level.

The incidental wildlife habitat benefits associated with these structures have been highlighted previously by Shields et al. (2002). Increased ecological benefits occur when the installation design allows for the establishment of permanent pools upstream of the pipe inlet and development of woody vegetation around the pool margins. These structures are not just creating isolated habitat patches, but instead are reconnecting riparian corridors fragmented by gully erosion.

The USDA Natural Resources Conservation Service (NRCS), the US Army Corps of Engineers, and other action agencies often support installation of these structures on a cost share basis in Mississippi and other parts of the United States.

Kevin Nelms, wildlife biologist with the USDA NRCS office in Greenwood, Mississippi, recently noted incorporation of habitat features in the installation design of several drop pipes in the Mississippi Delta: "We try to shape the basin to hold at least a semi-permanent pool, if not permanent water." Additionally, pool elevations are set to avoid killing existing stands of trees. Initially, the USDA NRCS engineer responsible for design was hesitant to pond water at the structures due to fears of attracting beaver, but beaver have not presented problems. Care in preserving existing trees and facilitating succession have resulted in a range of vegetative conditions adjacent to the drop pipes, ranging from willow stands to large hardwoods. In at least one case, large woody debris left from site clearing was placed in the pool to serve as a habitat feature. Landowners have been generally pleased with these design modifications. "One landowner duck hunts on the drop pipe pool!" Nelms enthusiastically noted.

Additional analyses from this research have provided further confirmation of the importance of designing and managing drop pipes to provide a larger (>0.1 ha [>0.2 ac]) habitat area, greater pool volume, and increased vegetative diversity consisting of trees, shrubs, and smaller plants to support a greater diversity and abundance of fishes (Smiley et al. 1999) and birds (Maul et al. 2005; Smiley et al. 2007). Analyses are underway to identify those habitat features that influence amphibians and reptile responses within drop pipe created habitats. Current research at the USDA ARS National Sedimentation Laboratory is designed to quantify impacts of installing drop pipes on annual sediment yield produced by active gullies. Ed Hackett, wildlife biologist with the USDA NRCS Agricultural Wildlife Conservation Center, is optimistic that habitat features will become increasingly common in drop pipe projects as US farm bill funds are now supporting a wider range of wildlife habitat measures.

REFERENCES

Maul, J.D., P.C. Smiley Jr., and C.M. Cooper. 2005. Patterns of avian nest predators and a brood parasite among restored riparian habitats in agricultural watersheds. Environmental Monitoring and Assessment 108:133-150.

Shields, F.D. Jr., P.C. Smiley Jr., and C.M. Cooper. 2002. Design and management of edge-of-field water control structures for ecological benefits. Journal of Soil and Water Conservation 57:151-157.

Smiley, P.C. Jr., S.S. Knight, C.M. Cooper, and K.W. Kallies. 1999. Fish richness and abundance in created riparian habitats of channelized northern Mississippi streams. Southeastern Fishes Council Proceedings 39:7-12.

Smiley, P.C. Jr., J.D. Maul, and C.M. Cooper. 2007. Avian community structure among restored riparian habitats in northwestern Mississippi. Agriculture, Ecosystems, and Environment 122:149-156.

F. Douglas Shields Jr. is a research hydraulic engineer and Charles. M. Cooper is an ecologist at the National Sedimentation Laboratory, USDA Agricultural Research Service (ARS), Oxford, Mississippi. Peter C. Smiley Jr. is an ecologist at the Soil Drainage Research Unit, USDA ARS, Columbus, Ohio.
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Title Annotation:IMPLEMENTATION UPDATE
Author:Shields, F. Douglas, Jr.; Smiley, Peter C., Jr.; Cooper, Charles M.
Publication:Journal of Soil and Water Conservation
Article Type:Report
Geographic Code:1USA
Date:Nov 1, 2007
Words:640
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