How to manage degraded monoculture plantations in South China: a perspective from reciprocal litter transplant experiment
Litter decomposition, an important component of nutrient cycling, is often one of the limiting factors for the development of monoculture tree plantations for restoration, and how to improve the litter decomposition rate remains as a major challenge. To help resolve this issue, we developed a mixed-litter transplantation approach to improve the litter decomposition and nutrient cycling in Schima superba, Cunninghamia lanceolata, Eucalyptus urophylla, and Acacia mangium monoculture plantations in China. The monospecific leaf litters of the four species were collected and their possible two-, three- and four-species combinations were transplanted between plantations. We examined the influences of home/away field, litter species richness, and litter composition on litter decomposition during 24 months treatment. A significant effect of litter composition on litter decomposition (Duration × Composition effect) was detected in E. urophylla plantation. The influence of litter richness on litter decomposition was significant in A. mangium plantation (Duration × Richness effect). The litter of C. lanceolata and A. mangium had a distinct home-field advantage, while the litter of S. superba had a distinct away-field advantage in decomposition. We observed a positive relationship between richness and litter decomposition in C. lanceolate plantation. The effect of Duration × Species Interaction on litter decomposition, was significant in E. urophylla plantation, indicating a non-additive effect. Litter decomposition in E. urophylla plantation could be explained by idiosyncratic model, and the rivet model may be appropriate to illustrate the litter decomposition in A. mangium plantation. Finally, since the litter decomposition in degraded A. mangium plantations had a distinct home-field advantage and was significantly affected by litter richness, transplanting mixed litters of neighboring plantations may be beneficial to improve its litter decomposition rate. Transplanting of S. superba litters due to the distinct home-field advantage to neighboring plantations such as E. urophylla plantation whose litter decomposition is significantly affected by litter composition, may be an effective management method for improving litters decomposition.