Spatiotemporal patterns of evapotranspiration along the North American east coast as influenced by multiple environmental changes

The North American east coast has experienced significant land-use and climate changes since the beginning of the 20th century. In this study, using the Dynamic Land Ecosystem Model 2.0 driven by time-series input data of land use, climate and atmospheric CO2, we examined how these driving forces have affected the spatiotemporal trends and variability of evapotranspiration (ET) in this region during 1901-2008. Annual ET in the North American east coast during this period was 648.3 +/- 38.6mm/year and demonstrated an increasing trend. Factorial model simulations indicated that climate variability explained 76% of the inter-annual ET variability. Although land-use change only explained 16% of the ET temporal variability, afforestation induced the upward trend of ET and increased annual ET by 12.8mm/year. Elevated atmospheric CO2 reduced annual ET by 0.84mm, and its potential impacts under future atmospheric CO2 levels could be much larger than estimates for the historical 1901-2008 period. Climate change determined the spatial pattern of ET changes across the entire study area, whereas land-use changes dramatically affected ET in watersheds with significant land conversions. In spite of the multiple benefits from afforestation, its impacts on water resources should be considered in future land-use policy making. Elevated ET may also affect fresh water availability for the increasing social and economic water demands. Copyright (c) 2014 John Wiley & Sons, Ltd.