Using an optimality model to understand medium and long-term responses of vegetation water use to elevated atmospheric CO2 concentrations.

摘要: Vegetation has different adjustable properties for adaptation to its environment. Examples include stomatal conductance at short time scale (minutes), leaf area index and fine root distributions longer scales (days - months) species composition dominant growth forms very long (years decades centuries). As a result, the overall response of evapotranspiration changes in environmental forcing may also change scales. The vegetation optimality model simulates optimal environ- mental conditions, based on assumption that are optimized maximize long-term net carbon profit, allowing separation adaptation, without need paramet- rization with observed responses. This paper discusses simulations responses today's elevated atmospheric CO2 concentrations (eCO2) temporal puts them context experimental evi- dence from free-air enrichment (FACE) experiments. Without any tuning or calibration, repro- duced general trends deduced FACE experiments, but, contrary widespread expectation eCO2 would generally decrease water use due leaf-scale effect conductance, our results suggest lead unchanged even increased water-limited climates, accompanied by an increase perennial cover.