EDI Staging Environment
A 2-year experiment with ambient, reduced, and enhanced precipitation (PPT) was designed to compare the performance of the encroaching C3 shrub (honey mesquite Prosopis glandulosa) to the dominant C4 grass (black grama Bouteloua eriopoda) in terms of photosynthetic rates and leaf water status. Precipitation manipulations dramatically enhanced natural variability and generated a range of rainfall scenarios that could have only been studied only after a multi-decade effort using natural conditions. Responses were highly asymmetric, with (PPT) additions generally influencing volumetric water content (vwc) to a greater extent than PPT reductions. Desert soils are usually close to their minimum water content and thus when soils were dry, the effects of reducing PPT were relatively minor compared to the effects of adding PPT. Volumetric soil water content was, on average, lower and more variable at the shallower (0–5 cm) depth (mean 9.3 ± 0.14%; range 5.7–14.3%) than at the deeper (30–50 cm) depth (mean 14.4 ± 0.12%; range 10.8–18.1%. This study is complete. For further information and results, see:
Throop, H., L. G. Reichmann, Os. Sala, and S. Archer. 2012. Response of dominant grass and shrub species to water manipulation: an ecophysical basis for shrub invasion in a Chihuahuan desert grassland. Oecologia 169: 373-383.
EDI is a collaboration between the University of New Mexico and the University of Wisconsin – Madison, Center for Limnology:
