Assessment of Spatial Metrics to Determine Rangeland Degradation Riaz Hedayati Mentor: Chandra Holifield Collins USDA-ARS SWRC The University of Arizona April 17, 2010

Background Soil erosion is a major cause of degradation in rangelands. If erosion patterns can be predicted, rangeland degradation can be more easily prevented. Traditionally, erosion potential is assessed using one of two ground-based measurements on a 2m x 6m plot: Transect Data (fetch:patch ratio) Point Data

Hypothesis Accounting for the spatial distribution of vegetation cover will be an improvement over traditional ground-based data for predicting erosion potential.

Study Sites Data was collected from 5 different field sites within southeastern Arizona. Each field site had 4 plots, and each plot measured 2m x 6m.

Methods A rainfall simulator was used on each plot to simulate erosion patterns and collect sediment yield (SYR) data.

Methods Point Interspace Area SYR Point Interspace Area

Methods Fetch:Patch Ratio SYR Fetch:Patch Ratio

Methods Photographs were digitally classified into vegetation and non-vegetation areas. Interspace FPI SYR Interspace FPI

Sediment Yield vs Point Data

Sediment Yield vs Fetch:Patch Ratio

Sediment Yield vs Interspace FPI

Conclusions Interspace FPI showed a slightly stronger relationship to sediment yield data than the point data or the fetch:patch ratio. Because it explicitly accounts for the spatial distribution of interspace areas, interspace FPI shows great promise as a tool for assessing degradation of ecological sites in semi-arid rangelands.

Dr. Chandra Holifield Collins Acknowledgements This Project would not have been possible without help from: Dr. Chandra Holifield Collins Dr. Jeffry Stone Rae-Landa Gomez-Pond Leonard Cratic III Jason Wong

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