Response of perennial grasses to precipitation in the northern Chihuahuan Desert: implications for grassland restoration

TitleResponse of perennial grasses to precipitation in the northern Chihuahuan Desert: implications for grassland restoration
Publication TypeConference Paper
Year of Publication2002
AuthorsYao J, Peters DC, Gibbens, Robert P., Havstad K
Conference Name87th Annual Meeting, Ecological Society of America
Date PublishedAugust 4, 2002
Conference LocationTucson, AZ
ARIS Log Number138635
AbstractGrasslands in the Chihuahuan Desert of the southwestern US have been invaded by less palatable shrubs over the past 50-100 years. Sustainable management and remediation of rangelands require detailed understanding of how various factors drive the conversion of grasslands to shrublands or allow grasslands to persist through time. We compared the impacts of precipitation on perennial grass cover by species during the course of shrub invasion with responses of grasses in areas where they have persisted. At the Jornada Experimental Range, NM, 106 1-m2 permanent quadrats were set up during 1915-1932 across a range of vegetation and soil texture types. Quadrats have been monitored periodically to quantify changes in cover through time. We separated the quadrats into two groups for the analysis: (1) quadrats that maintained dominance by perennial grasses through time, and (2) quadrats that were originally located in grasslands but were dominated by shrubs in 1995. We compared long-term data from 21 rain gauges with the vegetation data to identify the periods of rainfall to which abundance and growth of dominant species were the most sensitive for each species. Basal areas of black grama, mesa dropseed, and tobosa were correlated with long-term annual precipitation; the highest coefficients occurred with cumulative rainfall in the previous 6 to 8 years. Annual growth rates of these species were correlated with short-term rainfall occurring within the previous 15 months. Black grama response to precipitation was homogeneous among quadrats in persistent grasslands but heterogeneous among quadrats where shrubs currently dominate. Our results have important implications for remediation of desert grasslands since knowledge of grass responses to precipitation can be used to identify the windows of opportunity to initiate remediation projects.