Cattle use of riparian meadows in the blue mountains of northeastern Oregon.

The intensity and pattern of cattle use of small riparian meadows were studied by periodically sampling vegetative standing crop and by continuously monitoring meadows with time-lapse photography. Temperature and relative humidity were also measured in riparian and upland plant communities. Herbage standing crop at the end of the grazing season was similar under continuous grazing and the early and late grazing periods of a two pasture deferredrotation grazing system. Early grazing tended to decrease the total cattle occupation and the frequency of cattle occupation of riparian meadows when compared to continuous grazing. Late grazing tended to increase the frequency of cattle occupation but did not change the total cattle occupation of riparian meadows when compared to continuous grazing. Cattle were present on a given meadow site on about 60% of all days but for only 3-10% of the total daylight period. Cattle occupation of riparian meadows was greater during the afternoon hours. The seasonal pattern of cattle occupation was influenced by the location where cattle entered a pasture but not by seasonal temperatures. Temperature and the temperature-humidity index did not differ between riparian and upland plant communities between 12~00 noon and 6~00 p.m. Riparian meadows are narrow, highly productive plant communities occurring along stream courses. These meadows are usually dominated by grasses and grasslike plants but shrubs are often a major vegetative component. Cattle preference for riparian meadows is a major influence on overall grazing distribution on mounAuthors are assistant professor. Department of Agronomy, Oklahoma State University, Stillwater, and professor and associate professor, Department of Rangeland Resources, Oregon State Universitv, Corvallis. resoectivelv. Miller is located at the Eastern Oregon~Agricultural Reseakh Center at Bums, tie. This article is submitted as Tech. Paoer No. 7064. Orenon Anricultural Exoeriment Station,, Corval! is. This research was’supported by fuids fr;m the Oren thundershowers, which stimulated new forage growth on the uplands; and a microclimatic shift to more favorable conditions in the uplands (Bryant 1982). Over the last 2 decades, an increasing amount of attention has been given to the idea that excessive cattle use has reduced the usefulness of the riparian zone for wildlife species, especially fish (Ames 1977, Platts 1979, Thomas et al. 1979). Bowers et al. (1979) summarized 5 studies that indicated an average 200% increase in trout biomass when improper grazing was controlled and streams were managed for optimum trout habitat. Platts (1981) stated streams impacted by cattle overuse are wider, shallower, warmer, have less overhead cover, and have more fine sediment than unimpacted streams. He further stated livestock impacts are usually JOURNAL OF RANGE MANAGEMENT 38(3), May 1985 205 small cumulative changes that occur over several years (Platts 1982). Fencing and complete exclusion of grazing from riparian ecosystems is often recommended as a means of controlling livestock impact on riparian meadows (Armour 1979, Behnke and Raleigh 1979, Bowers et al. 1979). While fencing and livestock exclusion would certainly alleviate some aspects of the problem, it does not seem practically feasible on a broad scale and also implies that any level of livestock use would be detrimental. Fencing riparian zones to allow strict control of intensity and season of use seems to be a more reasonable approach. Light to moderate late season grazing has been most often advocated (Bowers et al. 1979, Platts 1981) and has shown good results in practice (Claire and Starch 1977, Kauffman 1982). However, the use of fencing will probably be limited economically to the larger and more important riparian areas (Platts 1979). Small riparian meadows along primary drainages may only range from 5 to 30 m in width but may total several miles in length in a single mountain range pasture. While these meadows are the riparian areas most susceptible to alteration by cattle grazing (May and Davis 1982), they are also the most difficult areas to fence. If cattle grazing patterns on these long, narrow riparian systems need to be changed, some combination of alternative grazing management practices must be employed. While all of the usual livestock distribution practices have been suggested as at least partial solutions, the implementation of grazing systems has been given the most attention. Continuous seasonlong or year-long grazing is generally considered to be a detrimental and unacceptable management scheme for riparian meadows (Reid and Pickford 1946; Pond 1961; Platts 1981, 1982), so some type of specialized grazing plan appears necessary. Platts (1981) rated most standard grazing plans as to their ability to maintain quality instream habitat; no system was rated better than fair. He stated none of the present grazing strategies would be satisfactory in this aspect. However, as more data have become available, Platts (1982) has indicated the situation may be better than first thought. The objectives of this study were to: (a) determine the intensity and pattern of cattle use of small riparian meadows under continu: ous and deferred rotation grazing management and (b) compare the temperature and relative humidity regimes of riparian and upland plant communities.