关键词: 植被恢复, 人类活动, 风沙活动, 气候变化, 榆树, 疏林草原

Abstract: Elm woodland steppe consists of sparse tree, shrub, and herbage. This vegetation type has uniqueness in ecosystem structure and function. The area of elm woodland steppe is decreasing recently in China, and lack of elm natural regeneration might be the key reason. The literature of elm natural regeneration was reviewed in this paper, focusing on population characteristics, tree-grass relation, microhabitat and human activity. Main conclusions are as follows: Spatial distribution of elm population develops from aggregated to random with age growth; elm and herbage coexists based on differentiation niche; vegetation coverage, microhabitat, human activity and enclosure all influence elm regeneration greatly. Some potential hot issues include pair distribution of elm plants, elm seeds invading into grass gap, effects of wind erosion and sand burying on elm regeneration and the best period of enclosure for elm regeneration. In the end, two key research directions are brought forward: relation of elm woodland steppe with globe climate change, and relation of elm woodland steppe with vegetation restoration in sandy land.

Key words: vegetation restoration, human activity, blown sand activity, climate change, elm, woodland steppe