Effect of pine allelochemicals on selected species in Korea

Abstract

The allelopathic potential of red pine (Pinus densiflora), pitch pine (Pinus rigida) and black pine (Pinus thunbergii) has attracted attention of Korean botanists for the last several years. It has been a point of interest why the understorey species are sparse (Lee and Monsi, 1963) and species growing there were similar with the other pine understoreys. It was hypothesized that the similarity of floristic composition of pine stands was caused by some regulating mechanism controlled by pine through the release of certain toxic substances (allelochemicals) in the soil. When the greenhouse soil was mixed with pine leaves, the growth of the plants was suppressed. However, the toxicity of the soil was gradually reduced, and ultimately diminished after several years. This further strengthened the idea of the possible release of allelochemicals by pine. Therefore, it deemed necessary to verify experimentally whether pine is indeed producing allelochemicals which, in turn, affect neighbouring plants. For this, several experiments were performed involving various species growing inside and outside the pine forests. The results obtained from various laboratory and field studies with respect to the allelopathic effects of pine and details of isolation of allelochemicals from pine materials are reported here.