Tree Growth Prediction in Relation to Simple Set of Site Quality Indicators for Six Native Tree Species in the Philippines

The gain in precision to explain the variation on tree growth performance as a function of a set of site indicators was analysed in a stepwise form, increasing its complexity and costs. Six native timber tree species were commonly found on farmer’s fields and planted under different types of agroforestry systems. Localization of trees to be used for measurement was achieved through individual interviews to assess timing of introduction of trees. Results proved that native tree species planted on farmers’ fields have similar growth rate other exotic timber species as Swietenia macrophylla that are widely spread in the Philippines. Nevertheless, the large fraction of the variation in tree performance that could not be explained by the biophysical site indicators measured
implies that farmers take considerable risk in planting trees on the basis of current “scientific” knowledge. The complement of “site characteristics” is probably “management”, and the low determination of tree growth by site properties may in fact be good news for the farmers.