Decomposition dynamics of plant residues in ecological tea plantations across different spatial scales

【Objective】To explore the natural decomposition change process of different plants in different spaces and provide a theoretical basis for the material nutrient cycle and maintenance of soil fertility in tea plantations. 【Method】The decomposition bag method was used to analyze decomposition characteristics,temporal dynamics,and differences in decomposition rates at different stages of plant residue decomposition in soil,forest canopy,and surface of tea(Camellia sinensis) prunings,light-barked birch(Betula luminifera),monkey camphor(Cinnamomum bodinieri),cedar(Cunninghamia lanceolata),and horsetail pine(Pinus massoniana). 【Result】The overall trend of natural decomposition of plant residues was fast-slow,and the rate of residue mass loss in different spaces was soil>surface>crown. Specifically,the rate of weight loss of tea prunings,light-barked birch,and monkey camphor gradually decreased with increase of height,and that of cedar and horsetail pine first increased and then decreased with increase of height. Multi-factor analysis of variance showed that space,time,tree species,and three-way interaction extremely significantly affected the dry weight residual rate of plant residues(P<0.01),with the most significant effect being time,followed by space,tree species,and the smallest being three-way interaction. Using Olson's exponential decay model to estimate the decomposition coefficients of each tree species,it was found that the overall decomposition rate of the forest canopy was lower than that of the surface and soil,and the decomposition rate of plant residues of coniferous species was lower than that of broadleaf species. There were differences in decomposition rates among different tree species,and the decomposition rate in the early stage was significantly greater than that in the late stage in the surface and soil. The annual decomposition rate of the forest canopy and soil was ranked as tea prunings>light-bark birch>monkey camphor>horsetail pine>cedar. At the same time,that of the surface was the inter-species ranking of tea prunings>light-bark birch>monkey camphor>cedar>horsetail pine. And the annual decomposition rates of tea prunings,light-bark birch,monkey camphor had a significant linear positive correlation with the space(P<0.05), the relationship between cedar and horsetail pine was insignificant(P>0.05). 【Conclusion】The surface and soil can improve the efficiency of plant residue utilization compared to the forest canopy,and appropriate removal of plant residues accumulated in the forest canopy and placing them in the soil and surface environments is more conducive to their degradation.