The objective of this paper is to provide insights into exotic and native invasive species dynamics using a conceptual model developed from the long history of research on native woody plant invasion into perennial grasslands in the southwestern United States. We first describe our new conceptual model that focuses on landscape characteristics (spatial configuration and connectivity) interacting with environmental drivers and biotic processes across multiple scales. We then provide support for the model using a long-term data set from southern New Mexico. Our results show that both local and spatially contagious processes can be important in generating temporal and spatial variation in native grass cover. Upland grass basal cover was related to both local (soil texture, precipitation, grazing by cattle) and spatial processes (shrub seed dispersal). Lowland grass basal cover was related to local processes associated with plant available water as well as grazing by cattle. We discuss new insights that this model has to offer for understanding, predicting, and managing exotic invasive species dynamics.

Additional index words: Chihuahuan Desert, conceptual model, landscape connectivity, landscape context.