Relationship between environmental parameters and Pinus sylvestris L. site index in forest plantations in northern Spain acidic plateau

Abstract

The assessment of forest productivity at early stages of stand developmentmay help to define the most appropriate silviculture treatment to be appliedfor each stand. Site index (dominant height at a reference age) is a useful toolfor forest productivity estimation. The aim of this study was to develop amodel to predict site index for Scots pine (Pinus sylvestris L.) plantations innorthern Spain acidic plateau by using soil (physical, chemical and biochemi-cal), climatic and physiographic parameters. To meet this objective, data from35 stands classified into three different site quality classes and 63 soil, cli-matic and physiographic parameters were examined in order to develop a dis-criminant model. After selecting 12 discriminant models which were biologi-cally consistent and presented the higher cross-validated rate of correct classi-fication, a model including four parameters (latitude, inorganic Al, porosityand microbial biomass carbon) as predictors was chosen. The discriminantmodel classified 71% of cases correctly and no inferior-quality stands weremisassigned to the highest quality class. Soil and physiographic parametersincluded in the above model are easily obtainable in the field or by simple la-boratory analysis, thus our results can be easily integrated in operationalforestry to determine site qualit