Litter Decomposition And The Effects Of Soil Fauna On The Litter Decomposition And Nutrient Release In The Coniferous Forest Of The Changbai Mountains, China

The litter decomposition plays a critical role in regulating the buildup of the soil organic matter, nutrients releasing, and influencing the carbon cycling. In recent decades, researchers in the world pay close attention to the function of soil fauna in litter decomposion and nutrients releasing. Soil fauna plays an important role in litter decomposition processes through breakdown of litter, digestion and stimulation of microbial activities.We used two different mesh sizes of litterbags (1mm and 0.01mm) to examine the decomposition prosess and nutrient release of the dominant tree species (Abies nephrolepis, Picea jezoensis) in the coniferous forest of the Changbai Mountains. The two different mesh sizes of litterbags can control the different body sizes of soil fauna in the litterbags. Variance analysis and correlation coefficient were used to analyze litter remaining mass, nutrient release, and soil fauna community. Further through the analysis of the soil fauna community and diversity characteristics, we understand the function of soil fauna in decomposition prosess and nutrient release of the monoculture and mixed litters.(1) Litter remaining mass was significantly affected by months in the field. There was a significant difference among three litter species. There was no significant difference of remaining mass between the upper and lower coniferous forest. Remaining mass of P. jezoensis is higher in the upper coniferous. There is no significant difference between observed value and predicted value of mixed litter remaining mass.(2) Each element content or remaining mass showed a significant time variation. There was a significant difference of element content and remaining mass among three litter species. Ca and Mn contents had a significant impact by litter species. P, Ca and Mg contents had a significant impact and litter species and habitat, decomposition for several months and their interaction can be the various elements of the content, and remaining mass was affected. There is no significant difference between observed value and predicted value of mixed litter element content and remaining mass.(3) 29 groups were collected during 3 years decomposition.29 groups were collected in the upper coniferous forest. Dominant group was Isotomidae and Oribatida. Common group was Pseudachorutidae, Mesostigmata, Hypogastruridae, Prostigmata, Tomoceridae, Enchytraeidae, Diptera larvae and Ptiliidae.23 groups were collected in the lower coniferous forest. Dominant group was Isotomidae, Oribatida and Pseudachorutidae. Common group was Mesostigmata, Hypogastruridae, Prostigmata, Tomoceridae, Enchytraeidae and Enchytraeidae. The Shannon-Wiener index, individual and group number had obvious time variation with the decomposition experiment. The Shannon-Wiener index index and group number in the upper coniferous forest were significantly higher than those of the lower coniferous forest. Shannon-Wiener index, individual and group number was without significant difference among three litter species.(4)Litter remaining masses in the 1 mm litterbags were significantly higher than those in the 0.01 mm litterbags, so that soil fauna can promote the decomposition of litter. Contribution of soil fauna on litter remaining mass of A. nephrolepis and P. jezoensis in the upper coniferous forest were higher than those in the lower coniferous forest, while contribution on mixed litter remaining mass in the upper coniferous forest was lower. Element remaining mass in the 1 mm litterbags was significantly lower than 0.01 mm litter. Through correlation brtwenm the element remaining mass and Shannon-Wiener index, individual and group number, effect degree of the soil fauna on elements release was different for each index of litter species, habitats and soil fauna.In conclusion, there was a significant interaction between litter decomposition and soil fauna in the coniferous forests of Changbai Mountain. The initial litter quality was not the main factor affecting litter decomposition and element release. Effects of soil fauna on different altitude litter decomposition are differences due to the different types of litter, soil animals of mixed litter decomposition is more pronounced in the lower coniferous forest, and the single species litter decomposition, which is more pronounced in the upper coniferous forest.