Response of a Southwest Montana Riparian System to Four Grazing Management Alternatives

-The effects of deferred rotation, time control (Savory Grazing Method), season-long, and livestock exclusion on streambank stability and trout habitat condition in a southwestern Montana riparian zone has been monitored since 1986. Although livestock exclusion appeared to improve channel conditions in 1986, there was no significant difference among any of the treatments thereafter. The decline in trout habitat condition appeared to be more a function of stream discharge and channel aggradation than grazing management. The lack of significant differences (P< 0.10) in bank stability among the various treatments during three consecutive drought years suggests that it is the interaction between grazing and stream discharge events that dictate the magnitude ofstreambank alteration. Downward shifts in livestock numbers will probably not limit streambank degradation and loss of trout habitat. Decreasing the length of time cattle have access to a stream reach and adjusting the grazing period to coincide with low streambank moisture levels shows promise for the improve­ ment of riparian zone condition. Wildlife and land managers seldom have to defend the importance of riparian ecosystems since the 1978 Calla­ way Gardens Symposium (Johnson and McCormick 1978). N ow efforts are directed to finding the most effective man­ agement alternatives for rehabilitating or protecting local wetland, floodplain, and streamside communities. This is especially so in the semi-arid and arid regions of the west­ ern USA where livestock grazing on public lands is a com­ mon practice. Successful rehabilitation or protection of riparian communities on livestock grazing allotments is thought to be unlikely without first placing the allotment under a resource sensitive level of stocking and manage­ ment intensity (Davis 1986). Resource sensitive stocking intensity may be interpreted as a reduction in livestock numbers. Although such a decision appears logical, a reduction in numbers does not eliminate the problem, it only restricts impact to smaller areas within the allotment pastures. Since the stream and its watershed function as a unit (Platts and Rinne 1985), those areas still being impacted will continue to limit the likelihood of riparian improvement along the stream course. This occurs because cuts in animal numbers do not mean an automatic modifi­ cation in animal grazing behavior; individuals will still feed in preferred sites and forage primarily on preferred plant species. Resource sensitive stocking rates and man­ agement requires that livestock grazing behavior be suffi­ ciently modified to limit negative impacts to the riparian community. In light of this need, we describe the response of certain riparian components to several grazing man­ agement methods that can be used to modify livestock grazing behavior.