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

2. 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

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

4. 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.

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

6. Methods
Point Interspace Area
SYR
Point Interspace Area

7. Methods
Fetch:Patch Ratio
SYR
Fetch:Patch Ratio

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

9. Sediment Yield vs Point Data

10. Sediment Yield vs Fetch:Patch Ratio

11. Sediment Yield vs Interspace FPI

12. 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.

13. 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

14. Thank You