Get reliable rangeland science

Climate extremes are a recurring natural phenomenon in the southwestern US. Records kept since 1919 at Texas A&M Agrilife Sonora Research Station (SRS) indicate that approximately 18% of years experienced precipitation < 75% of the long-term average (571 mm), while approximately 17% of years received > 125%. Contingency planning helps rangeland managers prepare for climatic extremes. Web-based tools have been developed to capture long-term weather data and make it available to rangeland managers. The objectives of this study were to: 1) evaluate the relationship between SRS-observed and Parameter-elevation Relationships on Independent Slopes Model (PRISM)-interpolated precipitation, and 2) introduce and apply web-based climate information tools for rangeland managers in the region. Using the University of Arizona�s Standardized Precipitation Index (SPI) Explorer tool georeferenced to the study location, annual (1919 � 2015) and monthly (2000 � 2015) PRISM precipitation and SPI values were calculated. The relationship between SRS and PRISM precipitation was determined using simple linear regression. Differences in mean 12 or 3-month SPI per decade were determined using analysis of variance procedures. Significant (P < 0.01) positive correlations were obtained for annual (r2 = 0.77, slope = 0.84, SE = 3.1) and monthly (r2 = 0.75, slope = 0.83, SE = 1.83) SRS versus PRISM precipitation. Numerical extremes (P > 0.1) in decadal 12-month SPI were the 1950�s (- 0.89 � 0.49) and the 1970�s (0.30 � 0.23). Numerical extremes (P > 0.1) in decadal April-May-June SPI were the 1960�s (- 0.31 � 0.38) and the 1940�s (0.39 � 0.28). PRISM interpolations of precipitation for the western Edwards Plateau region were of sufficient accuracy to be usable in retrospective analyses, but could be improved with inclusion of SRS data. 12 and 3-month SPI values can be used as one source of climatic information in proactive rangeland planning.