Date

6-2010

Degree Name

BS in Soil Science

Department

Earth and Soil Sciences Department

Advisor(s)

Chip Appel

Abstract

Soil temperature is a parameter that has been studied for a considerable time and from many different perspectives. However, relatively few studies have been conducted for taxonomic purposes and fewer still have focused on how changes in soil temperature related to global climate change may affect soil taxonomy. Soil temperature regimes are used to subdivide soils with similar properties that exist in dissimilar climate zones requiring different management practices depending on intended use. Seven sites with variable surficial features were used for this study within a cohesive sagebrush-steppe Eastern Sierra glacial moraine landform. Soil temperature was measured once a month for ten years, 50 cm below the soil surface. Vegetation density and subsequent plant litter on the soil surface were the most important factors controlling soil temperature and its annual and long term stability. Landscape position and slope shape also affected soil temperature, but may be primary factors determining vegetation type and vigor within a landform. Three of the seven sites had different temperature regimes, based on the ten-year average temperatures measured 50 cm below the soil surface, than was estimated by climate data at the beginning of the study. Typically, soil temperature is estimated by adding 1° C to the mean annual air temperature. The data collected in this study suggest the methods by which we measure and use soil temperature to classify soils are less than precise and should only be used as a secondary characteristic for distinction of soils within a survey area.

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