Abstract: The trends of herbage yield in different slopes on subalpine meadows in Shanxi were studied for three years.Herbage on subalpine meadows usually turns green in the mid or late April.Then the growth of herbage speeds up gradually with the rising temperatue and trends of herbage increases month by month.The change pattern and trends of herbage yield on all slopes are of unimodal curves.The high -yield season of hay is July on eastern and western slopes.On other slopes the season is August.Herbage begins to turn yellow in early September and its yield decreased until April of the next year, then herbage turn green again.The crude protein (CP) and phosphorus (P) in herbage are high in the early stage of growth and decreasing throughout the growing season.Crude fibre (CF) change is the just oppositive to CP andP.The high-yield season of CP is July on eastern, suothern and western slopes and is August on northern slope and hilltop.This tallies with the high yield season of hay.This season is the best period to use herbage.Except May and June,the herbage and nutrient yield of northern slope are much higher than of the slopes in green season.

Key words: herbage yield, trend, slope, subalpine meadow

摘要： 本文就山西亚高山草甸不同坡向牧草产量动态进行研究。三年定位研究结果表明,亚高山草甸牧草一般在四月中、下旬开始返青,随着气温的升高生长逐渐加快,牧草产量逐月增高,各坡向产草量动态均呈现单峰曲线变化规律。干草产量的峰值,东坡和西坡在七月,其它被向则出现在八月。九月上旬牧草开始枯萎,产草量开始下降,一直持续到翌年四月上旬牧草返青之前。牧草营养物质的变化,在生长前期粗蛋白质和磷含量高,随着牧草的生长发育逐渐减少,而粗纤维含量则相反。粗蛋白质产量高峰期,东、南和西坡在七月,北坡和山顶部在八月,与干草产量的高峰期基本吻合,此时正是牧草利用的最佳时期。除五、六月外其它各月青草期牧草产量和营养物质产量,北坡均显著高于其它各坡向(P<0.05)。

关键词: 牧草产量, 动态, 坡向, 亚高山草甸