Impacts of plant secondary metabolites from conifer litter on the decomposition of Populus purdomii litter

Abstract

A decomposition experiment of Populus purdomii litter, a commonly used afforestation species in the Qinling Mountains, China, was conducted. Water extracts of five conifer litters were used to treat P. purdomii litter and its soil. The P. purdomii litter was incubated at room temperature (20–25 °C) and constant soil moisture for 6 months. During the decomposition period, the dynamics of litter mass and nutrient contents were detected to investigate the impacts of plant secondary metabolites. The results indicate that litter extracts of Pinus tabuliformis, Platycladus orientalis, Pinus armandii and Larix principis-rupprechtii significantly inhibited the overall nutrient release of P. purdomii litter, while the last three types of litter extracts simultaneously inhibited its decomposition. Conversely, the litter extracts of Picea asperata significantly accelerated the overall nutrient release of P. purdomii. Generally, most of the conifer species, whose litter released terpenoids , phenolics, steroids, and aliphatic acids, will inhibit the decomposition and/or nutrient release from P. purdomii litter. Their negative effects on the decomposers and soil enzymatic activities indicates that planting diversity should be lower when mixed planted with P. purdomii.