Future changes in climate are likely to strongly affect plant physiological and growth parameters, and thus potentially influence competitive interactions among plants. We used rainout shelters and sprinklers to test the influence of changes in precipitation on aboveground physiological parameters and belowground growth of honey mesquite (Prosopis glandulosa) and black grama (Bouteloua eriopoda) at the Jornada Basin LTER. In this area of the northern Chihuahuan Desert, mesquite and other woody plants have encroached into former desert grasslands over the past 150 years.

Increased summer air temperatures in interior Alaska have caused drought stress and growth suppression in several boreal tree species. The response of Alnus tenuifolia (thinleaf alder) to a warming climate could substantially impact interior Alaskan floodplains due the role alder plays as the dominant N-fixer. We studied the effects of inter-annual variation in monthly meteorological and hydrological variables on annual alder radial growth (directly related to N-fixation input), the landscape variability in alder climate sensitivity, and the long-term trends in climate and hydrology.