RECREATIONAL IMPACTS ON EROSION AND RUNOFF IN A CENTRAL ARIZONA RIPARIAN AREA

Riparian areas are often focal points for recreation on western rangel ands. The objective of this study was to assess the impact of recreati on an soil compaction, runoff, erosion rates, and vegetation in a cent ral Arizona riparian ecosystem. This study was conducted in a Populus fremonrii Fraxinus pennsylvanica (Fremont Cottonwood Velvet ash) ripar ian community type. The dominate recreational use on the study site is camping and the area is accessible by automobile. A rainfall simulato r with an application rate of 5 in/hr (12.7 cm/hr) for 30 minutes was used to produce runoff. Initiation of runoff occurred significantly (P less-than 0.05) sooner on high use areas (3 minutes, 18 seconds) than light-use areas 8 minutes, 28 seconds). Total runoff um heavy-use are as was significantly (P less-than 0.05) higher (.12 in; 3.1 mm) when c ompared to light-use areas (0.008 in; 2 mm). Above ground vegetation r anged from 0 g/m2 in the heavy-use plots to 364 g/m2 in the light-use plots. Higher bulk densities and large areas of exposed fail surface m ight have contributed to differences in runoff.