Feedbacks between the atmospheric boundary layer and terrestrial ecosystems: implications for global-scale modelling

A model which simulates the daily growth of the atmospheric boundary layer was linked to a process-based, dynamic model of vegetation growth. The sensitivity of boundary layer growth and surface energy balance to vegetation characteristics was examined, including both short-term physiological effects, particularly through stomatal resistance, and longer-term effects, mainly acting through changes in leaf area index (LAI). A boundary layer growth model with a simple, static surface description was used as a comparison. The dynamic model was used to predict seasonal variation in LAI in different biomes, on the basis of the carbon and water balances. These were compared with observations of LAI in natural vegetation at a number of sites. The effect on these predictions of including boundary layer feedbacks was examined. The results have implications for global-scale dynamic vegetation models, which are being used to assess the current and future role of terrestrial ecosystems as carbon sinks under elevated CO2 and rising temperature.