Hydrologic Cycle Alterations Caused by Land Conversion for Bioenergy Crops under Climate Change

In order to meet increasing bioenergy demands, significant land areas are being converted to bioenergy crop plantations. These land conversions can contribute to changes to the ecosystem of the area, specially its hydrologic cycle.  The hydrologic cycle can be affected  since a bioenergy crops' high productivity is strongly linked with its water use.

Recently, researchers from the University of Illinois (USA) and Max-Planck-Institut für Biogeochemie (Germany) investigated the effect of bioenergy crops on the hydrologic cycle, with considerations for climate change. For their study, the researchers focused on the effect of two second generation bioenergy crops (miscanthus and switchgrass) on the hydrologic cycle of the Midwestern United States. 

By using a "mechanistic multilayer canopy-root-soil model", the researchers were able to capture the eco-physiological acclimations of bioenergy crops under climate change, and predict how hydrologic fluxes are likely to be altered from their current magnitudes. Also, observed meteorological data and Monte Carlo simulations were used to characterize the variability range of their predictions. Using maize as a basis (since most land conversion to bioenergy crops plantation are from maize plantations), the researchers observed that miscanthus and switchgrass utilized approximately 58% and 36% more water, respectively, for total seasonal evapotranspiration under present conditions. This can reportedly lead to an altered hydrologic cycle for the region. Accounting for climate change, the increase in atmospheric CO₂ decreased the evapotranspiration; however, the increase in air temperature and reduction in rainfall leads to a net increase in evapotranspiration due to climate change, which leads to the further alteration of the hydrologic cycle of the region. The full paper is published in the journal, Proceedings of the National Academy of Sciences of the United States of America (PNAS) (URL above).

Related information on Monte Carlo Simulations: http://www.palisade.com/risk/monte_carlo_simulation.asp