Effects of soil nutrients and environmental factors on site productivity in Castanea sativa Mill. coppice stands in NW Spain

Abstract

Ecological behaviour and productive capacity of chestnut (Castanea sativa Mill.) coppice stands are key factors in predicting forest growth and subsequent management decision, especially in areas where timber production is the primary objective. The effects of soil nutrients and environmental factors on site productivity in chestnut coppice stands in North-West Spain were studied. Site productivity described by site index was related to environmental characteristics, including edaphic, physiographic and climatic variables. The key factors affecting site productivity were evaluated according to two different statistical analyses: the CHAID procedure and parametric regression techniques. The CHAID algorithm applied separately to each type of variable revealed that the most important to explain SI were edaphic (sand and clay percentage, pH, stoniness) and climatic variables (summer and spring precipitation and mean annual temperature) (24 and 47 %, respectively). According to the regression tree and the parametric regression model for all variables, summer precipitation was the most significant variable (51 and 53 %, respectively). The results show the importance of climatic variables for chestnut coppice stands growth and provide further information about the ecology of the species in North-West Spain. The use of specimens from sites representing a wide range of habitats/growing conditions of this species means that both the results and methodology described here are of great relevance for improving the management of this species throughout its European range.