Water Cycle

Leaf area index of forests in Wisconsin is positively correlated to soil water availability, and to a lesser extent, to nutrient availability (Fassnacht and Gower 1997). As shown in the figure below, soil water availability is the balance between inputs (precipitation) and losses (canopy interception, evaporation, transpiration, overland flow, and deep drainage). Soil water availability controls stomatal conductance and biomass allocation to foliage, fine roots, and wood (Running and Gower 1991).