长白山高山苔原雪斑大白花地榆群落土壤氮素动态与生产力的关系

Soil nitrogen dynamics and productivity of snowpack Sanguisorba sitchensis community in alpine tundra of Changbai Mountain, China

在高山苔原冬季积雪覆盖的群落生长季短,但明显比周围群落生长茂盛。为了说明雪斑地段群落生长机理,对长白山苔原雪斑土壤氮素动态以及大白花地榆(Sanguisorba sitchensis)群落生产力进行了连续测定。雪斑群落土壤冬季相对温暖,最低日平均温度-1.4℃,裸露地段-16.9℃,全年水分条件充足;积雪期凋落物分解和氮矿化均在进行,土壤具有很高的氮素含量及矿化速率。大白花地榆地上部分净初级生产力为4046kg·hm-2·a-1。正是独特的水热条件和养分条件,以及具有很大的叶面积同化器官,高山苔原雪斑地段的大白花地榆群落才得以维持生存并表现出很高的生产力水平。

Aims Snowpack plant communities in alpine tundra are active in comparison with surrounding vegetation, despite the short growing season due to thick snow cover. Our objective was to understand the growth mechanism of snowpack communities. Methods The nutrient dynamics and primary productivity of snowpack Sanguisorba sitchensis community in alpine tundra of Changbai Mountain was investigated in different seasons. Important findings Soil temperature under snowpack during winter was warmer than snow-free areas, and the minimum temperature was significantly higher. Litter decomposition and nitrogen mineralization under snowpack were active even in winter, and nitrogen content was high with rapid mineralization. Annual net primary productivity was 4 046 kg·hm–2·a–1. The unique hydro-thermo conditions, nutrient cycling features and high leaf area index were key factors maintaining community structure and primary productivity.