Water cycling and availability exert dominant control over ecological processes and the sustainability of ecosystem services in water-limited ecosystems, which account for ~ 40% of global land area. Because dryland regions are heavily dependent on water, they have the potential to be dramatically impacted by hydrologic alterations emerging from global change. We examined how climate change may alter the ecohydrology of temperate dryland ecosystems and impact both ecosystem structure and the production of ecosystem services. Specifically, we quantified potential changes in drought severity and duration, examined how altered vegetation structure and biological invasions may mitigate or exacerbate these changes, and assessed the consequences of these changes for two key services: groundwater recharge and rainfed agriculture. We utilized a daily time-step, multiple soil-layer, ecosystem water balance simulation model (SOILWAT) to quantify patterns of soil moisture and water cycling in temperate drylands around the world. We examined both current climatic conditions and climate projected for the end of the century using 16 GCMs under RCP 8.5. Climate forecasts indicate increases in growing season length and variable increases in precipitation.
Results/Conclusions
Our preliminary results suggest that available soil water during the growing season may increase in western and central Asia and northern North America, but decrease in eastern Asia, southern North America, South America and the western Mediterranean. Annual wet days may decrease in most places except parts of Asia and northern North America, and the duration of growing season ecological droughts may increase by 22 days for deep soil and 7 days for shallow soil. Vegetation changes in response to climate change may exacerbate future drought, and woody-plant invasion into grasslands may magnify drought associated with climate change by accelerating seasonal drought onset, lengthening drought duration increased and increasing drought frequency. Changes in groundwater recharge are related to changes in precipitation, and climate change may decrease groundwater recharge in South America but increase it in North America and Central Asia. We found that rainfed agriculture requires sufficient wet degree days, but is limited by frequent high-temperature extremes, and that anticipated changes in these metrics may shift the distribution of temperate dryland areas that support rainfed agriculture poleward. These results provide insight into the overall consequences of climate change for temperate drylands and the services that they provide.