Study On Contribution Of Soil Fauna To Litter Decomposition Of Rhododendron Chrysanthum In Betula Ermanli Forest On Changbai Mountain

Litter decomposition plays a significant role in the process of material cycle and energy flow in terrestrial ecosystem, in which soil fauna is important by breaking down litters, digesting and stimulating microbial activities. Based on the study on contribution of soil fauna to litter decomposition of Rhododendron chrysanthum in Betula ermanii forest on Changbai Mountain, the thesis provides a scientific basis for maintaining ecological balance and rational development and utilization Betula ermanii forest ecosystems of Changbai Mountain.Dynamic of litter decomposition and nutrient-releasing, characteristics of soil fauna community in litterbags and the contributions of different factors in the process of litter decomposition of Rhododendron chrysanthum in Betula ermanii forest(42°03’41.23"N,128°03’12.75"E,1900m) on Changbai Mountain are studied by litterbag control method from late October2011to late October2012, on the base of field sampling and experimental analysis, with three different mesh sizes of litterbags(4mm,2mm and0.01mm) used to control soil fauna of different body sizes into the litterbag.The results of this study showed that the seasonal fluctuation and difference of decay rate of Rhododendron chrysanthum litters in three different mesh size litterbags were very obvious during the first year, which was supported by the data that the decay rate of Rhododendron chrysanthum litters from midsummer to early fall was much higher than that from early winter to late spring. At the end of the first year, the accumulate loss rate of Rhododendron chrysanthum litters in4mm size litterbags,2mm size litterbags and0.01mm size litterbags have approached to34.19%,31.22%and25.45%respectively, while remaining rate of litter mass has run up to65.81%by the end of the12-month experiment. A downward trend was generally seen on C/N in the remaining litters, while the total nitrogen content increased first and then decreased generally.Oribatida and Isotomidae played a predominant role in the decomposition process of Rhododendron chrysanthum litters from late October2011to late October2012. Among all the contributing factors, microbial factors were a little more important in the first half year and the involvement of soil fauna slowed the decomposition process down, when the environment was much colder and drier, however, with the change of temperature and moisture and the increasing involvement of macro-fauna and meso-fauna, contribution rates of macro-fauna and meso-fauna to litter decomposition have increased a lot in the following six months.The results indicated that there was a obvious difference between the contribution rates of macro-fauna and meso-fauna to the decomposition of Rhododendron chrysanthum litter. More specifically speaking, during the12months decomposition, the contribution rates of both macro-fauna and meso-fauna to litter decomposition is25.57%, of which the contribution rate of meso-fauna to litter decomposition is16.88%, which is much higher than the contribution rates of macro-fauna to litter decomposition (8.69%).Their contributions presented a prominent non-synchronization while the contribution rates of meso-fauna was much more higher than that of macro-fauna. The loss rate of nutrient elements was positively correlated with the total numbers of fauna in a significant level, the most remarkable phenomenon of which is that the correlativity between the total numbers of meso-fauna and the loss rate of organic carbon was significant at1%level.