A consensus in global ecology is that climate change is profoundly altering the process of terrestrial ecosystem. In particular, more and more attentions have been focused on the effects of snow pack on soil process in cold biomes recently, since climate change characterized by winter warming and extreme is changing the pattern of seasonal snow cover and freeze鄄 thaw cycles in the high鄄latitude and high鄄altitute regions. As yet, the results concerning the effects of seasonal cover and freeze鄄thaw cycles on soil process remain uncertainty, and little information has been available on the effects of snow pack on soil nitrogen tansformation in the subalpine forest of western Sichuan, China. In order to deeply understand the process of soil nitrogen transformation in the subalpine forest of western Sichuan under climate change scenarios, therefore, wintertime net nitrogen mineralization, net nitrogen ammonification, net nitrogen nitrification and microbial nitrogen immobilization in soils under three depths of snowpacks ( deep snowpack, middle snowpack and shallow snowpack) were measured in two subalpine forests of western Sichuan, which locates at the upper reaches of Yangtze River and the eastern Qinghai鄄Tibet Plateau. The top of soil columns sampled from Abies faxoniana + Betula albo鄄sinensis mixed forest and secondary fir forest were closed, and then in鄄situ incubated in the forest floor under deep snowpack, middle snowpack and shallow snowpack of the corresponding forest from November 2011 to April 2012, respectively. The results indicated that wintertime soil net

Total soil respiration is the sum of all carbon dioxide effluxes originating from litter, soil organic matter and roots, controlled by soil biological activity and environmental drivers such as soil temperature, air temperature, water content and photosynthetically active radiation. Aboveground litter is a key factor controlling soil carbon sequestration in terrestrial ecosystems as well as a very important part of the soil respiration. Because autotrophic and heterotrophic activity belowground is controlled by substrate availability, soil respiration is strongly linked to litterfall. For example, the amount of litter and its decomposition rate greatly affect the formation of soil organic matter and the supply of plant nutrients. Additionally, aboveground litter can directly and / or indirectly affect soil respiration via influencing other factors (e.g., soil water, soil temperature and microorganism). Dragon spruce plantations are mainly distributed in the subalpine and alpine forests of western Sichuan. In general, there is large amount of litter pool under the dragon spruce plantation. Therefore, the aboveground litter could have considerable contribution to total soil respiration in the plantation. Our objective of this study was to determine the contribution of aboveground litter to total CO 2 efflux in a subalpine dragon spruce plantation of western Sichuan. In order to evaluate the contribution of aboveground litter to total soil respiration, litter removal experiment was

As an important small scale disturbance, forest gaps are often considered to be major drivers in the natural forest regeneration. Moreover, forest gaps can play essential roles in soil processes including the dynamics of soil enzyme activity, since the snow, precipitation and sunshine duration could be redistributed in different gap location due to the effects of forest canopy. Subalpine forest in western Sichuan is a typical cold biome, which often displays sensitive responses to environment disturbance because of its fragile characters. As yet, more and more recent studies have concentrated on gap characteristics and seedling regeneration processes in this area, but little attention has been given to the effects of forest gap on soil enzyme activity. As we know, soil invertase and urease are the key enzymes involved in the soil organic carbon and nitrogen transformation, respectively, and the changes of their activities are closely associated with the carbon and nitrogen cycling. Therefore, to understand the effects of forest gap on soil invertase and urease activities at different seasons in alpine forest, a field experiment was conducted in a Picea asperata plantation forest in western Sichuan. The dynamics of soil invertase and urease activity under gap center, gap edge and under鄄canopy were investigated from June 2012 to May 2013. Soil samples in soil organic layer and mineral soil layer were collected in growing season (completely soil thawing stage,