SOIL CHRONOSEQUENCE OF THE SANTA RITA EXPERIMENTAL RANGE

Abstract

The Santa Rita Experimental Range (SRER) is the longest continuously active rangeland research facility in the United States, and it is also among the five oldest biological field stations. Located 45 minutes south of Tucson, Arizona, the SRER spans 52,000 acres offering rich soils and historical databases to conduct world-class ecological research. This project, conducted at the SRER, aimed to look at how soil composition and landscape ecology has changed over time and to make assumptions about how it will continue to change. Soils collected differed greatly in age, spanned back 350,000 years, and had noticeably different depths and compositions. Each individual soil horizon was determined and a portion was removed for analysis. Samples were placed into bags and taken to the Environmental Pedology lab, where characterization methods Electrical conductivity, pH, Loss on Ignition, Munsell Color, and Hydrometer Particle Size Analysis were carried out. From this data, we were able to determine the differences in soil composition over time to better understand to what extent this environment has varied, and what factors affect large-scale landscape change. Soils of the SRER, and most of Southern Arizona as a whole, have shifted to accommodate a warmer, drier climate, and are faced with dire circumstances and rapid successional change as the planet warms at unprecedented proportions.