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ABSTRACT: Riparian buffer strips can improve streams damaged by continuous livestock grazing, but they involve farmer costs that limit their application. We evaluated riparian intensive rotational grazing (IRG) as an alternative stream rehabilitation practice. We compared bank erosion, fish habitat characteristics, trout abundance, and a fish-based index of biotic integrity (IBI) among stations with either riparian continuous grazing, IRG, grassy buffers, or woody buffers along 23 trout stream reaches in southwestern Wisconsin during 1996 and 1997. After statistically factoring out watershed effects, stations with IRG or grassy buffers had the least bank erosion and fine substrate in the channel. Continuous grazing stations had significantly more erosion and, with woody buffers, more fine substrate. Station riparian land use had no significant effect on width/depth ratio, cover, percent pools, habitat quality index, trout abundance, or IBI score, but overall watershed conditions influenced these parameters. Buffers and IRG appear similarly effective for rehabilitating Wisconsin streams.
Keywords: Buffer strips, erosion, fish, fish habitat, index of biotic integrity, intensive rotational grazing, land use, riparian vegetation, streams
Agricultural degradation of stream ecosystems can be severe when riparian areas are used for crop or livestock production (Karr and Schlosser 1978; Wilkin and Hebel 1982; Wohl and Carline 1996; Wang et al. 1997). In Wisconsin, conventional livestock husbandry practices along streams have caused major declines in fish habitat quality and fish populations (Becker 1983; WDNR 1994). Most Wisconsin farmers use some combination of continuous grazing and confinement feeding to raise livestock (Fortenbery and Saupe 1995). Continuous grazing along streams often causes loss of vegetative cover, soil compaction, stream bank destabilization, and increased runoff and erosion (Wohl and Carline 1996). Confinement feeding leads to manure concentrations that, if managed poorly, can cause fish kills (Mason et al. 1991). Cultivation of large areas to feed confined livestock often results in sediment, nutrient, and pesticide delivery to streams (WDNR 1994).
Government agencies have spent nearly 100 million dollars in Wisconsin over the last 20 years on voluntary programs to reduce agricultural impacts on aquatic systems (Konrad et al. 1985; WDNR 1994; Wolf 1995). Most of this money has gone towards improved confinement feeding and manure management facilities, better cultivation practices, and streambank rehabilitation and protection. However, despite these expenditures, only minor improvements in stream ecosystems...