Percent change in mean annual vapor pressure deficit (1971-2099) under Hadley A2 for the Eastern Oregon study area, USA

This map represents the percent change in average annual vapor pressure deficit, simulated by the model MC1 between the 30-year periods 1971-2000 and 2070-2099, using the Hadley projected climate and A2 emissions scenarios. The average annual vapor pressure deficit for the respective 30-year periods decreased in all of the 5,311 grid cells of the Eastern Oregon study area. The greatest decrease was -33.04%; the least decrease was --40.97%; and the mean decrease was --36.49%

The vegetation model MC1 (e.g. Bachelet et al. 2001) was used to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget, and wild fire impacts at two study sites, one in eastern Oregon (Deschutes and Fremont-Winema National Forests) and one in Arizona (Apache-Sitgreaves National Forest area).  The work was funded by the USDA Forest Service (PNW 09-JV-11261900-003). Historical climate input data used to run the model were provided by the PRISM group (Chris Daly, OSU) at 30 arc-second (~800m) spatial grain. The model was also run using future climate change projections from three general circulation models: Hadley, CSIRO Mk3 and MIROC 3.2 medres. Future climate datasets were generated through statistical downscaling from general circulation model output using a simple anomaly method and the climatology (1971-2000) from the PRISM group at 30 arc-second spatial grain.  The model was run assuming that nitrogen demand from plants is always met, so that the nitrogen concentrations in various plant parts never drop below their minimum reported values. A CO2 enhancement effect increases productivity and water use efficiency as atmospheric CO2 concentration increases.