This completed dataset contains soil moisture data from a study at the Jornada Experimental Range (JER) in southern New Mexico. The study was designed to assess the effect of interannual variability in precipitation on average aboveground net primary productivity (ANPP) in Chihuahuan Desert grasslands. The study began in 2009 and has five precipitation treatments (see Methods). While the study began in 2009, contains 50 plots (10 per treatment) and is ongoing, these data were only collected from July 2011 to December 2013 in a subset of 20 plots (4 per treatment). This dataset is intended to provide information about the amount of water in the top 30 cm of soil as well as verify that experimental precipitation manipulations are effective. Figure of soil moisture by precipitation treatment: https://jornada.nmsu.edu/sites/jornada.nmsu.edu/files/files/data/soil_moisture_figure.jpg Metadata and data on EDI: https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-jrn&identifier=210328003
Increases in woody vegetation and declines in grasses in arid and semi-arid ecosystems have occurred globally since the 1800s, but the mechanisms driving this major land-cover change remain uncertain and controversial. Working in a shrub-encroached grassland in the northern Chihuahuan Desert where grasses and shrubs typically differ in leaf-level nitrogen allocation, photosynthetic pathway, and root distribution, we asked if differences in leaf level ecophysiology could help explain shrub proliferation. We predicted that the relative performance of grasses and shrubs would vary with soil moisture due to the different morphological and physiological characteristics of the two life-forms. In a 2-year experiment with ambient, reduced,and enhanced precipitation during the monsoon season, respectively, the encroaching C3 shrub (honey mesquite Prosopis glandulosa) consistently and substantially outperformed the historically dominant C4 grass (black grama Bouteloua eriopoda) in terms of photosynthetic rates while also maintaining a more favorable leaf water status. This study is complete.
Please refer to:
Throop, H., Archer, S. R. , and L. G. Reichmann. 2011. Response of dominant grass and shrub species to water manipulation: an ecophysiological basis for shrub invasion in a Chihuahuan Desert Grassland. Oecologia 169: 373-383.