青南高原气候变化及其对高寒草甸牧草生长影响的研究

Effects of climatic changes of south qinghai plateau on the alpine meadow

通过对1961 年以来青南高原气候变化的分析,发现该地区年平均降水量及秋季降水量无明显的变化趋势,且其年际间的波动趋于缓和;冬季(12～2 月)和春季(3～5 月)降水量的变化趋势呈现出逐年增多的趋势,气候倾向率分别为2.6 m m /10 a 和3.6 m m /10 a;夏季(6～8 月)降水量变化却表现出显著的减少趋势,其倾向率为- 6.5 m m /10 a。青南牧区牧草返青期气温回升速度在逐年减缓,而牧草枯黄期气温降低速度在逐年增大。该区的气候变化使青南高原主要优势牧草——嵩草的生长高度由80 年代末期的6～8 cm 下降到现在的3～5cm ,牧草开花期和籽粒成熟期的发育百分率普遍下降25% ～50% ,发育程度一般达不到50% ,天然草地产鲜草量和干草产量减少约为70% ～80% 。

The climatic variations since 1961 on Qinghai south plateau were analyzed in this paper. It indicated that the annual and autumn precipitation did not have significant tendency of variation. The winter (from December to February) and spring (from March to May) tended to increase by year, that tendency ratio of climate is 2.6 mm/10 a and 3.6 mm/10 a respectively. However, summer rainfall was decreased by year with the tendency ratio of 6.5 mm/10 a. The rate of air temperature rising at turning green period of pasture was increased by year. As the results, the height of Kobresia, the dominant species on the Qinghai south plateau, was decreased by 3 cm in the late 1980s. The development percentage of florescence and seed maturity of herbage by 20%～50% and greenness and dry yield of grassland declined by 70%～80%.