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<br />Conclusions <br /> <br />~ A number of limitations to the study results should be considered, including <br />~ the experimental design, the small-plot experimental methods, and the fact <br />-J that only one soil-vegetation complex was investigated. The qualitative re- <br />~ su1ts are more meaningful than the quantitative results. The most significant <br />result was that trampling by livestock could potentially reduce salinity and <br />sediment runoff from plots. This may be caused by reduced runoff resulting <br />from increased ponding of water in surface depressions created by livestock <br />and increased infiltration where surface crusts were pulverized. The pulver- <br />izing effects disappear after one wet-dry cycle, but the microdepressions <br />remain. The simulated rainstorms were of ;ligh,!r intensity and longer duration <br />than those encountered naturally. The proportional effects of trampling in <br />reducing runoff were not large in the simulated storms, but would be much more <br />pronounced for the smaller storms more common to the region. <br /> <br />Runoff from trampled plots had higher concentrations of sediment and salt than <br />runoff from untrampl ed plots, but the reduced runoff he1 p offset the effects <br />on overall salt and sediment yields. The plots were trampled under dry con- <br />ditions. We do not know what effect trampling under wet conditions would have <br />on water, salt and sediment yields. Infiltration rates on the study soil are <br />so low naturally, it is not likely that trampling under wet conditions could <br />significantly reduce infiltration rates. <br /> <br />While increased vegetation cover had some influence on decreasing water, <br />sediment, and salt yields, this generally happened at cover densities higher <br />titan those encountered naturally on the site. It was a quirk of the plot size <br />and location that resulted in cover densities as high as 34%, where cover at <br />the study site averaged 5 to 10%. In general, natural vegetation cover is so <br />low at the study site there is little likelihood further reductions in cover <br />will significantly affect runoff and water quality from these sites. While <br />trampling intensities as high as the 60% level tested in the experiment can <br />occur naturally on the range site represented by this study, intensities this <br />high are rare, as livestock rarely linger in one spot due to the low levels of <br />available forage. Realistically, trampling intensities will be much lower, <br />and any decreases in water, salt and sediment yield due to trampling will be <br />very small. Opportunities to manage salinity on these sites through grazing <br />management are probably very limited. <br /> <br />The qua 11 tati ve resul ts of thi s study, when considered in the context of the <br />study limitations, would appear applicable to the study site. While the study <br />site is representative of much of the low-rel ief, saline lowlands underlain by <br />Mancos shale in east-central Utah, it is not typical of the majority of arid <br />and semiarid range conditions. We do not expect the results to apply to other <br />sites.5 <br /> <br />5 Most studies reported (e.g. Branson et al., 1981) show trampling to <br />compact soils reduce infiltration and increase runoff. <br /> <br />27 <br /> <br />;...".....z <br /> <br />