Coniferous litter extracts inhibit the litter decomposition of Catalpa fargesii Bur. and Eucommia ulmoides Oliver

Abstract

In this study, the litter of Catalpa fargesii and Eucommia ulmoides was treated with the water extracts of 5 types of coniferous litter for a 0.5-year indoor, simulated decomposition experiment, and the effects of plant secondary metabolites (PSMs) from coniferous litter on the mass loss and C, N and P release of the 2 types of litter were detected. The results indicated that the litter extracts of Platycladus orientalis, Pinus tabuliformis, Pinus armandii and Larix principis-rupprechtii significantly reduced the decomposition and overall final nutrient release rates of the litter of C. fargesii and E. ulmoides (in which only the extracts of P. orientalis litter did not affect the mass loss of E. ulmoides litter). Correspondingly, significant decreases in the activity of soil cellulase and polyphenol oxidase were observed during the entire decomposition period, especially during the middle and later decomposition stages, indicating that the PSM release from coniferous litter might inhibit the decomposition and nutrient cycling of C. fargesii and E. ulmoides litter by depressing the activity of lignocellulolytic enzymes during mixed decomposition. In conclusion, more attention should be given to the effects of leached litter PSMs on the decomposition of other types of litter during mixed afforestation or in the mixed transformation of pure forests.