title: Modeled ecohydrological responses to climate change at seven small watersheds in the northeastern United States.
abstract: A cross-site analysis was conducted on seven diverse, forested watersheds in the northeastern United States to evaluate hydrological responses (evapotranspiration, soil moisture, seasonal and annual streamflow, and water stress) to projections of future climate. We used output from four atmosphere-ocean general circulation models (AOGCMs; CCSM4, HadGEM2-CC, MIROC5, and MRI-CGCM3) included in Phase 5 of the Coupled Model Intercomparison Project, coupled with two Representative Concentration Pathways (RCP 8.5 and 4.5). The coarse resolution AOGCMs outputs were statistically downscaled using an asynchronous regional regression model to provide finer resolution future climate projections as inputs to the deterministic dynamic ecosystem model PnET-BGC. Simulation results indicated that projected warmer temperatures and longer growing seasons in the northeastern United States are anticipated to increase evapotranspiration across all sites, although invoking CO2effects on vegetation (growth enhancement and increases in water use efficiency (WUE)) diminish this response. The model showed enhanced evapotranspiration resulted in drier growing season conditions across all sites and all scenarios in the future. Spruce-fir conifer forests have a lower optimum temperature for photosynthesis, making them more susceptible to temperature stress than more tolerant hardwood species, potentially giving hardwoods a competitive advantage in the future. However, some hardwood forests are projected to experience seasonal water stress, despite anticipated increases in precipitation, due to the higher temperatures, earlier loss of snow packs, longer growing seasons, and associated water deficits. Considering future CO2effects on WUE in the model alleviated water stress across all sites. Modeled streamflow responses were highly variable, with some sites showing significant increases in annual water yield, while others showed decreases. This variability in streamflow responses poses a challenge to water resource management in the northeastern United States. Our analyses suggest that dominant vegetation type and soil type are important attributes in determining future hydrological responses to climate change.
authors.affiliation: Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, 13244, USA.
authors.forename: Afshin
authors.initials: A
authors.lastname: Pourmokhtarian
authors.affiliation: Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, 13244, USA.
authors.forename: Charles T
authors.initials: CT
authors.lastname: Driscoll
authors.affiliation: US Forest Service, Northern Research Station, Durham, NH, 03824, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Campbell
authors.affiliation: Climate Science Center, Texas Tech University, Lubbock, TX, 79409, USA.
authors.forename: Katharine
authors.initials: K
authors.lastname: Hayhoe
authors.affiliation: Climate Science Center, Texas Tech University, Lubbock, TX, 79409, USA.
authors.forename: Anne M K
authors.initials: AM
authors.lastname: Stoner
authors.affiliation: Forest Service, Northern Research Station, Morgantown, WV, 26505, USA.
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Adams
authors.affiliation: US Geological Survey, Troy, NY, 12180, USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Burns
authors.affiliation: School of Forest Resources and Climate Change Institute, University of Maine, Orono, ME, 04469-5722, USA.
authors.forename: Ivan
authors.initials: I
authors.lastname: Fernandez
authors.affiliation: Department of Environmental Resources Engineering, SUNY-ESF, Syracuse, NY, 13210, USA.
authors.forename: Myron J
authors.initials: MJ
authors.lastname: Mitchell
authors.affiliation: US Geological Survey, Montpelier, VT, 05601, USA.
authors.forename: James B
authors.initials: JB
authors.lastname: Shanley
mesh_terms: D002980:Climate; D057231:Climate Change; D017753:Ecosystem; D065928:Forests; D009511:New England; D010944:Plants; D045483:Rivers; D012987:Soil
chemical_list: D012987:Soil
keywords: CMIP5; climate change; ecohydrology; ecosystem modeling; northeastern United States; water stress; water use efficiency; watershed