亚高山草甸不同坡向牧草产量动态的研究

本文就山西亚高山草甸不同坡向牧草产量动态进行了研究。经三年的定位研究其结果表明：亚高山草甸牧草一般４月中、下旬开始返青，之后牧草随温度升高生长逐渐加快，牧草产量逐月增高，各坡向牧草产量动态均呈现单峰曲线的变化规律。干草产量的峰值，东坡和西坡在７月，其它各坡向则出现在８月。９月上旬牧草开始枯萎，产草量便开始下降，一直持续到翌年４月牧草返青之前。牧草营养物质的变化，生长前期粗蛋白质和磷含量高，随牧草的生长发育逐渐减少。粗纤维则相反。粗蛋白质产量高峰期，东、南和西坡在７月，北坡和山顶部在８月份，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５、６月外，青草期其它各月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）。

A STUDY ON THE TRENDS OF HERBAGE YIELD IN DIFFERENT SLOPES ON SUBALPINE MEADOWS

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 temperature and 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 agin.The regular changes of nutrient content in herbage are crude protein(CP)and phosphorus(P)are high in the early stage of herbage growth and decrease with the growth and development.Crude fibre(CF)is the just opposite to CP and P.The high- yield season of CP is July on eastern,southern 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 that of the other slopes in green season of herbage.