The objective of this study was to quantify relationships between grazing management and macroinvertebrate assemblages in mountain meadow associated stream reaches in California. We conducted a cross-sectional survey of 58 low gradient meadow stream reaches located within large pastures and allotments in the Sierra Nevada and Southern Cascade mountain ranges. Current livestock management activities at the selected sites had been in use for at least 10 years prior to this study. Mean pasture/allotment size was 18,000 ac, with a median of 3,000 ac. Macroinvertebrate sample collection commenced in early June at low elevation sites (3000 to 5000 ft) and ended in late August at high elevation sites (7,500 to 9,000 ft). Substrate size class (cobble, gravel, fines), percent available solar radiation reaching stream water surface, and embeddedness of streambed substrates were measured along each macroinvertebrate sampling transect. Grazing and management metrics were determined by survey of grazing managers at each study site. Relationships between grazing practices, stream characteristics, and stream macroinvertebrate indices were examined.
Results/Conclusions
Management activities varied across sites. Off-site attractants were present a minimum of zero and a maximum of 34 days per year. Total days per year spent on livestock distribution efforts at sites ranged from 0 to 41. We found that livestock distribution effort (days) was statistically correlated (P<0.10) with several macroinvertebrate indices. The act of implementing a distribution practice (yes/no) was not significantly correlated to any macroinvertebrate indices. Positive correlations were found between livestock distribution effort and all sensitive (intolerant of pollution or habitat degradation) macroinvertebrate indices, while negative correlations were found for all insensitive (tolerant of pollution or habitat degradation) macroinvertebrate indices. These results provide strong evidence that active, consistent implementation of common livestock distribution tools is associated with increased riparian health.