Decomposition of mixed litter of Pinus koraiensis, Quercus mongolica and Acer mono

This paper is aimed to study several key problems about the rate and process of litter decomposition of several main tree species in the natural Korean pine broadleaved forest ecosystem in Jiaohe, Jilin of China. The research contents include the decomposition rates, nutrient dynamics, mixed effects and mechanism of mixed effects in litters of several common plant species ( Pinnus koraiensis, Quercus mongolica and Acer mono). The research method was litter bag burying. The results were: 1) The initial concentrations of nutrients in the litters varied significantly, and the initial concentrations of nitrogen (N) and phosphorus (P) were significantly and positively correlated with the decomposition rate. 2) The ratios of mass loss among the litters of different tree species varied significantly, and the variance increased over time, but not followed the linear pattern. 3) The decomposition rates of litters increased at first phase of whole decomposition process, then became steady after middle phase. 4 ) The decomposition rates of broadleaved tree species were higher than those of conifer if considering the decomposition of a single litter. 5) During the 395 days decomposition,the concentrations of organic carbon (C), total N and P, and total potassium (K) showed the changes dynamically. Both N and P were accumulated, but N released remarkably after short term accumulation; The C and K had net release; the ratio of C to N decreased continiously. 6 ) There were great mixed effects in the decomposition rates of litter mixtures of Pinnus koraiensis Quercus mongolica and Quercus mongolica Acer mono, also the same mixed effects to the nutrient dynamics during the decomposition process, especially for N and P, however the modes (positive or negative) of mixed effects and strengths were extremely complex. Whether or not mixed effects occurred and which mode mixture effect is in were determined by the characteristics of composed litters.