Ecosystems in Transition: Causes and Cosequences of Dramatic Shifts in Growth Form Dominance

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Abstract00-75350BriggsEcosystems in transition: Causes and consequences of dramatic shifts in growth form dominanceWorldwide, the structure and function of many ecosystems are in transition due to global changes in climatic means and extremes, increased atmospheric CO2, nitrogen deposition, alterations in land management, and the spread of invasive exotic species. In the tallgrass prairies of the eastern Great Plains, the expansion of shrub cover and forest encroachment into this grassland is a widespread phenomenon. This is a serious conservation concern since tallgrass prairie is considered an endangered ecosystem. The objective of this project is to use a tallgrass prairie ecosystem to evaluate the patterns, mechanisms and ecological consequences of transition to closed-canopy shrub/woodland. We will test hypotheses regarding the role that resource availability plays in woody plant expansion in grasslands. Evaluating this grassland-to-shrubland transition at levels from the leaf to the landscape will provide both the mechanistic specificity, as well as the large-scale generality, required for successful conservation efforts.