The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Tuesday, January 29, 2008 - 11:10 AM
Soils, Resilience, and State and Transition Models
Jeffrey E. Herrick1, Skye Wills1, Debra Peters1, Arlene Tugel2, and Brandon Bestelmeyer1. (1) USDA-ARS Jornada Experimental Range, MSC 3JER Box 30003, New Mexico State University, Las Cruces, NM 88003, (2) Jornada Experimental Range, USDA-NRCS, MSC 3JER Box 30003, NMSU, Las Cruces, NM 88003
State and transition models are based on the assumption that less resilient systems are more susceptible to state changes. The objective of this paper is to show how two different types of soil properties contribute to resilience through their direct and indirect effects on ecosystem processes, and through feedbacks with plants, and how this information can be used to guide the sampling of dynamic soil properties. Relatively static soil and topographic properties including texture, mineralogy, depth, slope and aspect determine, together with climate, the ecological site potential. This potential is realized through the establishment of plant and soil biotic communities, and through the subsequent modification of dynamic properties throughout the soil profile including infiltration and water holding capacity and nutrient availability. We will present results of new analyses of variability in soil properties at multiple spatial scales that illustrate both the interactions between relatively static and dynamic soil properties, and the appropriate scales for sampling. We will conclude with the results of a modeling exercise showing how changes in a relatively static soil property (soil surface texture) generated by a state change in an upwind ecological site can trigger soil-plant feedbacks resulting in changes in both dynamic soil properties and plant community composition, and discuss the application of an understanding of changes in relatively static and dynamic soil properties to assessment and monitoring of the effects of conservation practices (including CEAP).