Submitted to: US-International Association for Landscape Ecology
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2002
Publication Date: April 23, 2002
Citation: YAO, J., PETERS, D.C., HAVSTAD, K.M., GIBBENS, R.P., HERRICK, J.E. SPATIAL VARIATION IN SHRUB INVASION AND LOSS OF PERENNIAL GRASSES IN THE CHIHUAHUAN DESERT: A MULTI-SCALE APPROACH. 17TH ANNUAL SYMPOSIUM, US-INTERNATIONAL ASSOCIATION FOR LANDSCAPE ECOLOGY. 2002. ABSTRACT P. 30. Technical Abstract: Chihuahuan Deserts are characterized by large-scale invasion of perennial grasslands by shrubs over the past century. A number of interacting factors have been implicated in this invasion, including grazing by cattle, drought, herbivory by small animals, and reduction in fire frequency. Spatial variation in shrub invasion has been observed across these landscapes that cannot be explained using plot-scale studies. We investigated the relationship between spatial and temporal variation in these factors and the replacement of perennial grasses by shrubs using permanent 1 m2 quadrats sampled since 193. Quadrats (n=105) were located across the range of soil and plant communities found at the 78,266-ha Jornada Experimental Range LTER site in southern New Mexico, USA. We synthesized additional long-term data collected at multiple spatial scales to identify the factors that influence grass cover in the quadrats. Persistence of the dominant species, black grama, was positively related to processes at the quadrat (sand content, perennial grass production) and landscape scales (distance to nearest shrub-dominated community, variation in spring and winter rainfall). Grass persistence was negatively related to inter-annual variation in grass production. Our results can be used to identify the conditions most resistant to shrub invasion and most likely candidates for remediation.