Tree growth prediction using size and exposed crown area

We address the relationships between tree growth rate and growing environment for 21 co-occurring species. Tree growth rates are obtained from mapped plots at the Coweeta Long-Term Ecological Research site in the southern Appalachian Mountains. We employ high-resolution aerial photography to assess the light environment for trees growing in these plots, using exposed crown area (ECA) as a surrogate for light interception. The relationship between growth and ECA is compared with two other growth predictors: tree size and shade-tolerance classification. We find that ECA is an excellent predictor of tree growth (average R^2 = 0.69 for nine species). When ECA is combined with tree size, growth rate prediction is improved (average R^2 = 0.76). Tree size alone is also a strong predictor of tree growth (average R^2 = 0.68). Shade-tolerance classification, by contrast, is a poor predictor of tree growth.