Abstract: Leymus chinesis, Stipo baicalensis and Filifolium Sibiricum are the dominant forage species in the north of Horqin nature grassland which belongs to NC-Ash type.It has high content of crude protein and ash, and suitable for sruing fine-wool sheep.The forages are in rich nutrition at last ten days of July, so, it is the best time to cut and store of forages.Light, temperature and water are the major factors effecting on forage yield during growing period.Correlation between forage yield and precipitation is positive, and yield is also controlled by Eurasianplanetary circulation and circulation index.

Key words: Grassland of Leymus chinesis, NC-Ash type, Circulation index

摘要： 科尔沁草原北部以羊草+贝加尔针茅+线叶菊为建群种的天然牧草,其粗蛋白质和粗灰分含量较高,属氮碳－灰分型,适宜发展毛肉兼用型的细毛绵羊。7月下旬牧草营养丰富、草质优良,是打草贮存的最佳期。在天然牧草生长期间,光热水因子起着主导作用;产草量与降水量呈正相关,同时受5～7月欧亚大气环流作用和西风环流指数的强弱所制约。

关键词: 羊草天然草地, 氮碳-灰分型, 大气环流, 环流指数