HR: 0800h
AN: H51H-0882    [Abstracts]
TI: Climate Change Effects on Temperate Forest Ecosystems: Putting Groundwater Into the Equation
AU: * Brolsma, R J
EM: r.brolsma@geo.uu.nl
AF: Utrecht University, P.O.Box 80115, Utrecht, 3508TC, Netherlands
AU: Bierkens, M F
EM: m.bierkens@geo.uu.nl
AF: Utrecht University, P.O.Box 80115, Utrecht, 3508TC, Netherlands
AB: Many attempts have been made to predict the influence of changing climate on ecosystems. Models developed for this purpose most often concentrate on vegetation in connection with soil moisture but usually omit groundwater. However in temperate climate groundwater can have a profound effect on the reaction of vegetation to climate change, because it strongly influences the spatial temporal distribution of soil moisture and therefore water and oxygen stress of vegetation. Here we focus on the effect of climate change on the zonation of vegetation and groundwater dynamics along a hill slope. To study this we developed a fully coupled hydrological-vegetation model, for a temperate forest ecosystem. The vegetation model is based on the carbon assimilation model of Farquhar et al. (1980) and the extension of Daly et al. (2004), which includes transpiration for the vegetation and accounts for the response to low soil moisture content. Further extensions have been made to account for vegetation response to high soil moisture contents due to high groundwater levels, vegetation growth and light competition. To simulate the hydrology the saturated-unsaturated flow model STARWARS (van Beek 2002) has been used. This coupled model was compared to measured semi-hourly flux tower data of H₂O and CO₂, showing good results. Long simulation runs of 1000 years were performed to study the effect of climate change. The results show that changing rainfall regimes have a small but significant influence on transpiration and carbon assimilation of the vegetation and groundwater recharge, but it has a large influence on interception evaporation. Change in precipitation affects vegetation types the most in areas where groundwater is near the surface. Due to the buffering capacity of both the vegetation and the hydrological system the effect on growth rate of vegetation is small, resulting in relatively small changes in the zonation of vegetation between dry adapted and wet adapted tree species. This model shows the importance of using a coupled groundwater vegetation model in temperate lowland areas. The coupled hydrological-vegetation model allows for detailed studies of changes in spatial temporal patterns of vegetation under changing climate.
DE: 1807 Climate impacts
DE: 1813 Eco-hydrology
DE: 1829 Groundwater hydrology
DE: 1847 Modeling
SC: Hydrology [H]
MN: 2007 Fall Meeting