Assessment of Spatial Assessment of Spatial Metrics to Determine Metrics to Determine
Rangeland DegradationRangeland Degradation
Riaz HedayatiRiaz HedayatiMentor: Chandra Holifield CollinsMentor: Chandra Holifield Collins
USDA-ARS SWRCUSDA-ARS SWRC
The University of ArizonaThe University of Arizona
April 17, 2010April 17, 2010
BackgroundBackground Soil erosion is a major cause of degradation in Soil erosion is a major cause of degradation in
rangelands. If erosion patterns can be predicted, rangelands. If erosion patterns can be predicted, rangeland degradation can be more easily prevented.rangeland degradation can be more easily prevented.
Traditionally, erosion potential is assessed using one of Traditionally, erosion potential is assessed using one of two ground-based measurements on a 2m x 6m plot:two ground-based measurements on a 2m x 6m plot:
Point Data
Transect Data(fetch:patch ratio)
HypothesisHypothesis
Accounting for the spatial distribution of Accounting for the spatial distribution of vegetation cover will be an improvement over vegetation cover will be an improvement over traditional ground-based data for predicting traditional ground-based data for predicting erosion potential.erosion potential.
Study SitesStudy Sites
Data was collected from 5 Data was collected from 5 different field sites within different field sites within southeastern Arizona. southeastern Arizona.
Each field site had 4 plots, Each field site had 4 plots, and each plot measured and each plot measured 2m x 6m.2m x 6m.
MethodsMethods A rainfall simulator was used on each plot to simulate A rainfall simulator was used on each plot to simulate
erosion patterns and collect sediment yield (SYR) erosion patterns and collect sediment yield (SYR) data.data.
MethodsMethods
Point Interspace AreaPoint Interspace Area
SY
RPoint Interspace Area
MethodsMethods
Fetch:Patch RatioFetch:Patch Ratio
SY
RFetch:Patch Ratio
Photographs were digitally Photographs were digitally classified into vegetation classified into vegetation and non-vegetation areas.and non-vegetation areas.
MethodsMethods
Interspace FPIInterspace FPI
SY
R
Interspace FPI
Sediment Yield vs Point DataSediment Yield vs Point Data
SYR = 0.02*(point interspace area)1.79
R2 = 0.50
0
10
20
30
40
50
60
0 20 40 60 80 100
Point Interspace Area (%)
SY
R
Sediment Yield vs Fetch:Patch Sediment Yield vs Fetch:Patch RatioRatio
SRY = 37*(fetch:patch ratio)0.44
R2 = 0.500
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Fetch:Patch Ratio
SY
R
Sediment Yield vs Interspace FPISediment Yield vs Interspace FPI
SYR = 46*e-2.32(interspace FPI)
R2 = 0.58
0
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1
Interspace FPI
SY
R
ConclusionsConclusions
Interspace FPI showed a slightly stronger Interspace FPI showed a slightly stronger relationship to sediment yield data than the relationship to sediment yield data than the point data or the fetch:patch ratio. point data or the fetch:patch ratio.
Because it explicitly accounts for the spatial Because it explicitly accounts for the spatial distribution of interspace areas, interspace FPI distribution of interspace areas, interspace FPI shows great promise as a tool for assessing shows great promise as a tool for assessing degradation of ecological sites in semi-arid degradation of ecological sites in semi-arid rangelands.rangelands.
This Project would not have been possible without This Project would not have been possible without help from:help from:
Dr. Chandra Holifield CollinsDr. Chandra Holifield Collins
Dr. Jeffry StoneDr. Jeffry Stone
Rae-Landa Gomez-Pond Rae-Landa Gomez-Pond
Leonard Cratic IIILeonard Cratic III
Jason WongJason Wong
AcknowledgementsAcknowledgements
Thank YouThank You
