Vector Competition Analysis for Interaction between Pinus tabulaeformis-Platycladus orientalis at a Mixed Plantation in Xishan, Beijing

Vector Competition Analysis is a graphical diagnostic approach based on vector analysis and regression analysis that assess grow th and nutrient interactions between two species competing for the same resources.Response parameters are compared in a bivariate model that graphically depicts vectors of changing biomass production or nutrient uptake relative to competition-free treatment. In this paper, a 44-year -old mixed plantation of two tree species (Pinus tabulaeformis and Platycladus orientalis)was compared with competition-free pure stands for their biomass production and nutrient (N, P and K) uptake using this new technique. Although the mixture is in favor of the biomass production of Platycladus orientalis, nutrient deficiency of Platycladus orientalis apparently occurred at the present stage. In contrast, grow th of Pinus tabulaeformis was suppressed and the inhibitory effect for grow th of Pinus tabulaeformis was associated with excessive nutrient uptake. These results have demonstrated the potential of vector competition analysis to quantify the tree nutrient interactions in a mixed plantation.