Effects of snow pack on winter soil nitrogen transformation in two subalpine forests of western sichuan

Abstract

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

Soil Nitrogen Responses to Soil Core Transplanting Along an Altitudinal Gradient in an Eastern Tibetan Forest

“…In this study, the abundance of AOB was higher at A2 and A3 during most of the sampling period (Figure 4c). Higher ammonium concentration was observed only in the early growing season and later growing season, likely due to N mineralization over the winter [41]. This result suggests that inorganic N may determine the distribution of AOA and AOB in alpine forest soils by providing the substrate for microbial mineralization.…”

“…The thickest snow cover in A1 may offer an ideal combination of moister and warmer soil conditions that can keep the soil warm [39,40]. However, the thinner and shorter duration of snow cover at A3 had a more sensitive response to solar radiation [41], which may produce a higher soil temperature.…”