Landscape-scale analyses provide new insights into desertification

TitleLandscape-scale analyses provide new insights into desertification
Publication TypeConference Paper
Year of Publication2004
AuthorsYao J, Peters DC, Havstad K, Bestelmeyer BT
Conference Name19th Annual Symposium of the US Regional Association of the International Association for Landscape Ecology: Transdisciplinary Challenges in Landscape Ecology
Date PublishedMarch 30-April 2
Conference LocationLas Vegas, NV
ARIS Log Number159357
Keywordscross-scale, desertification, invasion, landscape-scale, woody plants
AbstractDesertification, or the invasion of woody plants into perennial grasslands with associated changes in ecosystem stability, is a pervasive problem that affects arid and semiarid systems worldwide. Although many studies have been conducted on woody plant invasion, we still lack a basic understanding of controls on the spatial and temporal variation in desertification dynamics at multiple scales. Our objective was to develop and test a new conceptual framework of woody plant invasion that explicitly includes a hierarchy of interacting scales. Our model includes landscape characteristics, such as connectivity, interacting with both fine scale processes (e.g., competition) and broad-scale drivers (e.g., climate) to generate cross-scale interactions. We provide support for our model from a combination of long-term studies, process-based experiments, and integrative simulation model analyses conducted in southern New Mexico. Results from >100 permanent quadrats established in the early 1900's show both high spatial and temporal variation in patterns in shrub invasion and grass persistence through time. Much of this variation was explained by landscape-scale features related to connectivity of shrubs (i.e., distance to the nearest shrubland when a quadrat was established). Experimental results show the importance of variation in herbivory on grass survival at grass-shrub ecotones with high spatial variation among locations. An integrated simulation model and multiscale experiments are being used to examine key processes and constraints operating across scales. Thus, our results support the cross-scale landscape model of desertification and provide a framework for understanding and predicting variation in woody plant invasion dynamics.