Tree Growth as Affected by Soil Moisture Availability

Merchantable volume growth in a managed southern pine forest was measured every 3 years from 1940 through 1960. Available soil moisture in the surface foot was estimated for each day of the 21 growing seasons. The soil‐moisture estimates were combined with estimates of potential evapotranspiration to calculate indexes of potential growth. Linear regressions of measured growth on calculated potential growth explained 95 to 97% of the variation about the regression lines. With sufficient soils information and past measurements of growth, foresters may be able to estimate current annual growth in timber stands.