长白山高山苔原带雪斑地段牛皮杜鹃群落的土壤氮矿化与净初级生产力

采用土壤温度连续观测和土壤原位培养，研究了长白山高山苔原带雪斑地段牛皮杜鹃群落的土壤温度、土壤氮矿化及净初级生产力.结果表明: 在非生长季的积雪期(10月下旬-5月上旬),土壤养分呈上升趋势，土壤以氮矿化为主，为翌年植物的生长提供了充足的氮素.其中雪斑地段土壤(平均温度-3.0 ℃)的氮矿化能力更强，速效氮增加量为3.88 g·m^-2,非雪斑地段(平均温度-7.5 ℃)为1.21 g·m^-2. 在生长季节(5月中旬-8月下旬)，土壤氮素含量下降，以固持为主;秋季植物停止生长后，土壤速效氮又呈上升趋势;到冬季，由于积雪的作用,雪斑地段土壤温度维持在0 ℃左右或略低，促进了土壤氮的矿化,而非雪斑地段土壤温度则处于冻结状态.氮素矿化能力的差异是雪斑地段牛皮杜鹃群落净初级生产力高于非雪斑地段群落的主要原因，也是植被空间分异的重要驱动因子.

Soil nitrogen mineralization and primary productivity in Rhododendron aureum community of snowpacks in alpine tundra of Changbai Mountain

Based on continuous observation of soil temperature and in situ incubation, this paper studied the effects of snow packs on soil temperature, soil nitrogen (N) mineralization, and primary productivity of Rhododendron aureum community alpine tundra in Changbai Mountain. During the snow-covered period of non-growth season (from last October to early May), test soil had an increasing N content, and accumulated sufficient mineralized N for plant growth in the coming year. The soil under snow packs in snow-covered period had a mean temperature -3.0 ℃, and its N mineralization was more vigorous, with available N increasedby 3.88 g·m^-2; while the soil with no snowpack had a mean temperature -7.5 ℃, and the available N only increased by 1.21 g·m^-2. During growth lseason (from mid May to late August), soil N content decreased. In autumn when plants stopped growing, soil available N content tended to increase. In winter, the soil temperature under snowpacks kept at around 0 ℃ or a little lower, which promoted soil N mineralization,while that with no snowpack was in a frozen status. The difference in soil N mineralization was the key factor resulting in the higher primary productivity of snowpack Rh. aureum community and the driving force for the spatial variation of vegetation.