高寒矮嵩草草甸禾草种群的生长发育节律及环境适应性

本文以矮嵩草(Kobresia humilis)草甸中草质优良，并在畜牧业生产中有重要作用的7种禾草为对象，研究了它们的生长发育节律、干重季节变化以及与环境因子之间的相互关系。其结果表明：7种禾草在矮嵩草草甸中的分布格局属非随机性的集中分布(Aggregated dispersal)。它们的生长发育节律和干重季节变化具明显的差异。单株分蘖数自返青开始随降水量、日照和≥3℃积温的增加而增加，到孕穗初期为最大。禾草种群生长发育的低温临界值为3℃。地上部分干重的积累与生长发育节律、≥5℃、≥10℃的积温，降水量和土壤含水量密切相关，生殖枝株高与≥10℃的积温密切相关。相关分析表明，温度是影响矮嵩草草甸禾草种群生长发育的主导因子(P<0.01)，其次是降水量和土壤含水量(P<0.01) 。

THE GROWTH RHYTHM OF THE GRASSES POPULATIONS AND THEIR ADAPTABILITY OF ENVIRONMENT IN KOBRESIA HUMILIS MEADOW

This paper has studied the growth rhythm, dry weight of grasses of seven species and relationship between factors of environment. The quality of grasses in Kobresia humilis meadow, which is main vagetation type of Qinghai Xizang plateau, is excellent, so they occupy a very important place in animal husbandry. The results are as follows:The distribution is an aggregated dispersal on grasses of seven species in Kobresia humilis meadow. The number of individual tillers after green up increases with increase of precipitation, sunshine time and accumulated tem, greater than 3℃ and reaches peak in early booting period.The critical value of low tem. is 3℃ for growth of grasses population. The populations begin to bud bursting at average daily air tem. ≥3℃.The course of development become quickly at average daily air tem. ≥ 5℃. The aboveground dry weight of an individual after green up begins to increase with increase of≥5℃, ≥10℃ accumulated tem. and precipitation. The dry weight is biggest at late August or early September.The populations need about 134 days from green up to ripeness of seed. In this period, the accumulated tem. of≥ 5℃ is about 949.7℃; accumulated tem. of≥10℃ is about 485.6℃; sunshine time is about 812.0 hours, amount of accumulated precipitation is about 324.9mm. The primary factor affecting growth is temperature (p<0.01) , and the second is precipitation and water content of soil (p<0.01)