Ecological distribution of arbuscular mycorrhizal fungi in alpine grasslands of Tibet Plateau. The Spatial Pattern of Plant Nitrogen and Phosphorus in Relation to Climate Factors in Chinese Grassland Transect 黄土高原不同退耕年限坡地植物比叶面积与养分含量的关系 The carbon contents and the relationship with the calorific values of 67 plant species in Inner Mongolia grasslands Reproductive strategy of grassland plant