Community variation on Songnen grassland after different burning time Grazing succession pattern or alkalized Aneurolepidium chinense grassland on Sougnen plain Analysis of plant individual characteristies on Songnen grassland after different burning time Leaf nitrogen and phosphorus stoichiometry in 80 herbaceous plant species of Songnen grassland in Northeast China Competition and Coexistence of Leymus Chinensis and its Main Companion Species in the Songnen Grasslands Leaf traits of 66 herbaceous species in Songnen grassland in Northeast China Changes among soil nematode community characteristics in relation to different vegetation restoration practices in the moderate degraded grasslands of Songnen The Effect of Hill-Building Activities of Ants on the Species Diversity of Plant Communitiesin Songnen Grassland 蚂蚁筑丘活动对松嫩草地植物群落多样性的影响 THE COMPARISON STUDY ON WATER ECOLOGY OF TWO PUCCINELLIA COMMUNITIES IN SONGNEN GRASSLAND Regionalization and distribution pattern of vegetation of Northeast China Morphological changes of phytoliths in Leymus chinensis under saline-alkali stress