Modeled ecohydrological responses to climate change at seven small watersheds in the northeastern United States

Afshin Pourmokhtarian, Charles T. Driscoll, John L. Campbell, Katharine Hayhoe, Anne M.K. Stoner, Mary Beth Adams, Douglas Burns, Ivan Fernandez, Myron J. Mitchell, James B. Shanley

Research output: Contribution to journalArticle

10 Scopus citations

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 CO2 effects 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 CO2 effects 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.

Original languageEnglish (US)
Pages (from-to)840-856
Number of pages17
JournalGlobal Change Biology
Volume23
Issue number2
DOIs
StatePublished - Feb 1 2017

Keywords

  • CMIP5
  • climate change
  • ecohydrology
  • ecosystem modeling
  • northeastern United States
  • water stress
  • water use efficiency
  • watershed

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science(all)

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    Pourmokhtarian, A., Driscoll, C. T., Campbell, J. L., Hayhoe, K., Stoner, A. M. K., Adams, M. B., Burns, D., Fernandez, I., Mitchell, M. J., & Shanley, J. B. (2017). Modeled ecohydrological responses to climate change at seven small watersheds in the northeastern United States. Global Change Biology, 23(2), 840-856. https://doi.org/10.1111/gcb.13444