Relevant Spatial Scales for a National Inventory of Soil Change.

There is significant interest within the National Cooperative Soil Survey to develop state and transition models as tools to covey the impacts of land use and restoration. State and transition models have been recommended for ecosystems in which vegetation dynamics respond to multiple axes, including fire regimes, soil erosion, management, and the traditional succession-grazing axis of the range model. These conceptual models will be based on the integration of soil and vegetative properties in order to organize information about the ecosystem, allowing for assessment of potential benefits and risks of management actions. Traditionally, the development of state and transition models has focused on vegetation dynamics with little integration of soil properties. Recently, researchers have proposed a focus on dynamic soil properties as indicators of soil change in complex ecosystems. As with vegetation, changes in these key properties could affect a variety of ecosystem services including stabilization against erosion, forage production, carbon storage and regulation of nutrient cycling and water supply. A comprehensive assessment of vegetation and soil dynamics in managed ecosystems depends on the analyses of multiple scales across a gradient of management and environmental conditions. Research is needed to understand the optimal spatial and temporal scales at which vegetative and dynamic soil properties are correlated and can thus be integrated to describe ecologically significant states. Second, information is needed on how soil-plant properties respond to mechanisms of transition (land use).