Leaf area index (LAI) can be considered at the vegetation and individual plant level. For an individual plant, leaf area index is defined as the amount of leaf area per unit ground area of the horizontally projected crown. It provides information on light interception per unit crown area, which determines on the one hand the light acquisition by a plant and the shade it casts on its shorter neighbors. It can be measured precisely for small individual plants, and estimated non-destructively for larger plants/trees. Because of its obvious relationship with productivity, leaf area index is a central component in productivity models for plants (Horn 1971, Sterck & Schieving 2007), vegetations (Monsi & Saeki 195, Anten 2005) and globe (Zhao & Running 2010).
LAI = Aleaf / Asoil