Partitioning direct and indirect effects reveals the response of water-limited ecosystems to elevated CO2

摘要: Increasing concentrations of atmospheric carbon dioxide are expected to affect assimilation and evapotranspiration (ET), ultimately driving changes in plant growth, hydrology, the global balance. Direct leaf biochemical effects have been widely investigated, whereas indirect effects, although documented, elude explicit quantification experiments. Here, we used a mechanistic model investigate relative contributions direct (through assimilation) (via soil moisture savings due stomatal closure, area index) elevated CO2 across variety ecosystems. We specifically determined which ecosystems climatic conditions maximize The simulations suggest that on net primary productivity large variable, ranging from less than 10% more 100% size effects. For ET, were, average, 65% Indirect tended be considerably larger water-limited As consequence, total effect had significant, inverse relationship with wetness index was directly related vapor pressure deficit. These results major implications for our understanding response projections fertilization, because, typically understood easily reproducible models, far challenging difficult constrain. Our findings also provide an explanation discrepancies between experiments productivity.