Sevilleta LTER: Long Term Ecological Research in a Biome Transition Zone

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The Sevilleta LTER (SEV) research site is located on the Sevilleta National Wildlife Refuge in central New Mexico, where a junction of four biomes (Great Plains Grassland, Great Basin Shrub-steppe, Chihuahuan Desert and Montane Coniferous Forest) provides a rich assortment of Biome Transition Zones (BTZs). Interacting with a highly variable climate, elevational range, complex topography, geology, and soils, this provides a complex spatial and temporal template for this project. SEV combines long-term research and an increasing array of collaborative, short-term research efforts that range from genetics to remote sensing of the landscape and focus on the floral and faunal properties of transitions between grass and shrub life forms represented by two components of the Chihuahuan Desert biome and their junctions with the Great Plains shortgrass steppe biome. The proposed new work will build upon and expand foundation studies ongoing since 1989 and initiate new long-term landscape experiments and measurements to develop and test a general theory of the dynamics of BTZs. A new conceptual framework will expand past studies to focus on patch-scale dynamics, biotic and abiotic drivers, and the consequences of different patch types, sizes, and their mosaics to landscape and regional scale dynamics. A series of experiments will be initiated that focus on the importance of plant-soil-animal-microbe interactions and feedbacks with ecosystem dynamics. An iterative approach combines a synthetic simulation model with data collected from short- and long-term interdisciplinary studies as a framework for extending our conceptual model to additional transitions in the future. Results will provide an important regional context for studies conducted within the shortgrass steppe biome at the SGS LTER and within the Chihuahuan Desert biome at the JRN LTER. Future studies will expand to other major biome representatives at SEV (e.g., shrubsteppe of the Colorado Plateau, Pinon -Juniper woodlands). These studies on other BTZs and ecotones present at SEV will further develop and test BTZ theory applicable to understanding and predicting ecosystem response to global change. Simulation modeling will be used to predict changes in the location and composition of BTZs through time under changes in climate and disturbance regime. Because the region is likely to experience a decade-long drought, directional changes in climate, and increases in atmospheric deposition, an understanding of the key processes driving patch and ecotone dynamics is critical to an ability to manage and preserve the biodiversity and natural resources of these systems. Common properties and patterns that can be used for many types of boundaries at many scales are expected. Extrapolating from patch mosaics, processes, and dynamics to the landscape and region will also be critical in determining the contribution of the Sevilleta to regional and global biodiversity and biogeochemical cycles.