| Abstract | Light is a limiting resource for trees within the understory of a forest because of the extensive shading produced by the crowns of the overtopping canopy. Thus, access to light is a critical determinant of growth for understory trees. The effect of the understory light gradient on tree growth has been modeled by a differential equation describing diameter growth rate of a target tree as a function of its neighborhood, which is the sum of the basal areas of the trees within a given radius that overtop it. However, current application of the neighborhood function fails to adjust the growth rates of overtopping trees for their own light environment. To create a more realistic model, we developed a system of coupled differential equations that simultaneously adjusts the growths rates of all the trees within a forest stand for light availability using neighborhood estimates. We will present analyses of our model, using data on 26 years of tree growth from forest dynamics plots in New Zealand, and compare its ability to predict growth rates with simpler models. |
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