高寒小嵩草草原化草甸植物群落结构特征及其生物量

COMMUNITY STRUCTURE AND BIOMASS DYNAMIC OF THE KOBRESIA PYGMAEA STEPPPE MEADOW

小嵩草（Ｋｏｂｒｅｓｉａｐｙｇｍａｅａ）草原化草甸的主要植物有３５种，隶属１１科，３０属。小嵩草为优势种，次优势种有异针茅（Ｓｔｉｐａａｌｌｉｅｎａ）、美丽风毛菊（Ｓａｕｓｓｕｒｅａｓｕｐｅｒｂａ）、紫羊茅（Ｆｅｓｆｕｃａｒｕｂｒａ）等；生活型以地面芽植物为主（６５．７１％），其次为地下芽植物（３４．２９％）；地上、地下部分生物量垂直分布呈典型的金字塔模式。地上、地下生物量主要分布在０－１０ｃｍ冠层和土层中，分别占地上、地下总生物量的９１．７９％和９０．４３％。每个植物类群生物量季节变化可由Ｌｏｇｏｓｔｉｃ模型表示：Ｗ＿Ｉ＝ｋ＿ｉ／［１＋ｅｘｐ（Ａ＿Ｉ－Ｂ＿ｉｔ）］枯枝落叶生物量变化呈“Ｖ”型曲线。在生长季各类群生物量绝对增长速率具明显的差异，平均每天每平方米可生产干物质２．７９ｇ．年地上净生产量为３６８．４ｇ／ｍ￣２。所固定太阳能值为６６５５．１６ｋＪ／ｍ￣２．其中莎草类占３５．１０％，禾草类占２３．３３％，杂类草占３４．１５％，枯枝落叶占７．４２％。光能利用率为０．１０９７％。

An investigation on the community structure and biomass dynarnics of the Kobresia pygmea community was carried out mainly in a plot of 30m × 30m. at the Haibei Research Station of Alpine Meadow Ecosvstem from May to September in 1989. 35 species belonging to 30 genera and 11 families were recorded.Besides the first dominant species Kobresia pygmaea. the do- minant species also included Stipa aliana. Saussurea superba and Festuca rubra. etc.,The 65.7%of the species were hemicryptophytes. and the other 34.3%were geophytes.The vertical distribution of both above and below ground biomass of the community showed a pyramidic pattern. The 91.8% of the above ground biomass and 90.4%of the below ground biomass were respectively concentrated in the 0-10cm layers above and below the ground. The seasonal biomass dynamic(Wi) of the different plant groups could be described by Logistic equations:Wi =Ki/[1+exp(Ai-Bi·t )]; where t referred to growing days since the 21st April. Ki referred to the maximum biomass. i referred to different plant groups. Ai and Bi were constants. While the seasonal changes of the litter biomass showed a V- curve. i.e. ,the litter biomass was the lowest in Summer. The growing rates of different plant groups were different. but average growing rate of the community biomass was 2.79g/m￣2·d￣(-1) in the growing season. and the net production of the community was 368. 4g/m￣2·d￣(-1), corres- ponding to an assimilated solar energy of 6655.16kJ/m￣2·a￣(-1) among which the sedges. grasses. forbs and litter occupied 35.19%,23.33%,34.15%and 7.42% respectively.