Environmental control of leaf area production: Implications for vegetation and land-surface modeling

摘要

Leaf surface area per unit ground cover (leaf area index, LAI) is one of the major controls on plant productivity and biospheric feedbacks on atmospheric energy and water exchanges. Nearly all vegetation and land-surface models include parameterizations of LAI, however not much research currently focuses on the validation of simulated responses of LAI to environmental change. The objective of our research was to quantitatively review the plant science literature to extract information on the response of LAI to variations in soil moisture, soil fertility and atmospheric CO_2. Our synthesis confirms that LAI is likely co-limited by a number of resources, including water, nitrogen and light. Atmospheric CO_2 influences LAI in much the same manner as other plant resources. When CO_2 supply is strongly limiting to gross primary production (i.e., at relatively low CO_2 concentrations), LAI is strongly correlated with CO_2, whereas when CO_2 is abundant, LAI sensitivity to CO_2 dramatically decreases. Such a nonlinear relationship between leaf area production and atmospheric CO_2 may introduce a potential bias for global change modeling, particularly in the simulation of low-density vegetation that has the potential to significantly increase canopy size without inducing self-shading.