Fenceline contrasts: grazing increases wetland surface roughness

A warming earth has lost substantial mountain-stored frozen fresh water, thus generating a pressing need for greater liquid–water storage within upper-elevation riparian systems. Liquid–water storage can be enhanced by avoiding microtopographic channels that facilitate land drainage and rapid runoff. A number of authors have attributed certain forms of wetland hummocks and inter-hummock channels to grazing livestock but there is little evidence in the scientific literature for a cause and effect mechanism. We used comparisons at six fencelines on four meadow and wetland complexes to test the null hypothesis that grazing management makes no difference in hummocks and inter-hummock channels measured as surface roughness. Surface roughness was measured both photogrammetrically (photo) and with an erosion bridge (EB), and the measurements expressed as surface roughness indices (SRIs). Wetland surface roughness inside fenced areas was 44 (EB) and 41 (photo). Wetland surface roughness outside fenced areas was more than 50 % higher ( p