Effect Of Seasonal Snow Cover On Soil Meso- And Microfauna Diversity During Leaf Litter Decomposition In Timberline Ecotone

Soil fauna is not only an essential part of the ecosystem, but also is an active participant in the ecosystem material circulation and energy flow. Timberline ecotone system has a higher habitat complexity and species diversity than the adjacent, is sensitive to regional and global climate change. Seasonal snow cover is a prevailing climate in high latitudes and high altitudes. The currently crucial scientific questions are: whether or how does the soil fauna community to change affected by seasonal snow cover and freeze-thaw cycles in the timberline ecotone Litter decomposition? Effects on litter decomposition is significant? What are the relationships between growing period and snow covered period? At the same time, global warming is how to change seasonal snow and affect soil fauna community structure in the timberline ecotone of litter decomposition? These unresolved questions limit our understanding of soil ecological processes in the timberline ecotone with seasonal snow cover.Subalpine timberline ecotone as a mid-latitude and high-altitude alpine which most representative ecotone character, and obviously seasonal snow cover time a length of 5-6 months, climate vertical differentiation is clear that the study of global warming scenarios ideal place for winter soil ecology research process. Litterbag with plant debris of Actinothuidium hookeri, Cystopteris moupinensis, Epilobium angustifolium, Salix paraplesia, Sorbus rufopilosa, hododendron lapponicum, Deyeuxia scabrescens, Ajuga ovalifolia, Festuca wallichanica, Poa crymophila, Pedicularis roylei, Polygonum paleaceum,12 representative plants in the timberline ecotone, and their mixed litter were incubate in the dark coniferous forest, timberline and alpine meadow, respectively. The structure and diversity of soil fauna, the mass loss rates of litter were investigated at different stages during a year, snow cover season and growing season both of two years, analyzes the influence vegetation and seasonal variations of soil fauna during leaf litter decomposition, and analyzes the relationship between environmental factors (snow, freezing and thawing frequency, temperature) and the structure and diversity of soil fauna community and the decomposition process. The results are helpful to deeply understand the effect of seasonal snow cover events on the process of the timberline ecotone ecosystem and its relationship between the ecological process in snow cover season and growing season.A total of 15052 individuals of soil fauna were collected,7533 individuals of soil fauna were collected at the end of snow cover season,7519 individuals of soil fauna were at the end of growing season, according to preliminary identification, they belonged to 1 phyla 8 classes 16 orders and 82 families. Many groups of Collembola and Acarina are present both snow cover season and growing season, such as poduridae, Liacaridae etc., soil fauna individual density and group density were highest at the end of the growing season, Group is the most abundant in timberline. Each elevation has unique species, such as Cryptognathidae in coniferous forest, Microdispidae in timberline, and Zerconidae on alpine meadows. Although the growing season temperature synchronization, lush plant growth, and soil fauna adapt to survive, but because of its mobility and migration, the number of individuals of soil fauna is less than at the end of the snow cover season 14. Litter bag provides a relatively stable environment at the snow cover season, suitable for dominant groups, the individual was increased.Acarina and Collembola were the dominant groups in timberline, at different altitudes Acarina and Collembola distributions were quite different. In the coniferous forest Collembola were dominant group, on the alpine meadow Acarina were dominant group. With the decomposition, soil fauna community structure also changes, Collembola trend growth in the number of individual, the number of soil fauna groups reduce. Different decomposition rates in different substrates was different effected by the leaf thickness, soft and hard, whether it has leathery a significant impact litter decomposition rate, mixed decomposition response or promote or inhibit decomposition, different soil fauna response to different substrates of litter, leading to different degree of influence on the decomposition of soil animals, such as the relatively few number of individuals in Rhododendron lapponicum.Different altitudes, different seasons and different litters of soil fauna community diversity index were differences. Relatively speaking, Shannon index H’, Pielou index J and Margalef index D at the end of the growing season was high at the end of the snow cover season, coniferous forests relatively high than timberline and alpine meadow at the end of snow cover season, timberline was the highest at the end of the growing season, Simpson index C opposite.Correlation analysis and Canonical correspondence analysis (CCA) showed that the seasonal snow cover, elevation gradient, temperature, frequency of freeze-thaw, litter composition significantly affect timberline ecotone community structure of soil fauna in litter decomposition, environmental factors and soil fauna community structure all affect litter decomposition. Regression analysis showed that in timberline ecotone litter decomposition mainly effected by seasonal snow, freeze-thaw cycle, temperature and other environmental factors, several environmental factors explained 42.6% of variation of litter mass loss rate, soil fauna factor explained 5.0%, and together explained 44.9%. Thaw frequency, elevation gradient, seasonal snow, temperature and other environmental factors are key factors in litter decomposition in timberline ecotone, soil fauna in timberline ecotone impact on litter decomposition of relatively weak than environmental factors.In conclusion, the seasonal snow cover has an important impact on the flow of alpine ecosystems, material recycling and energy, is an important factor alpine climate. Snow and snowmelt by regulating the temperature and humidity, affect not only the distribution of alpine ecosystems biomes, and acting on the plant community growth and litter decomposition. These results provide further understanding of the impact of winter seasonal snow alpine ecosystems provide some basic data.