疏林草原榆树天然更新研究进展

A Review on Elm Natural Regeneration in Woodland Steppe in Sandy Land

疏林草原是由稀疏乔木以及灌木和草本植物组成的植被类型,其生态系统结构和功能有一定独特性。目前榆树疏林草原面积减少,榆树种群更新不良可能是重要原因。从种群特征、草树关系、微生境、人类活动等4个方面对榆树种群更新进行总结。主要结论是:随年龄增长,榆树种群表现为由集聚到随机的分布趋势;榆树与草本植物通过占据不同生态位实现共生;植被盖度与微生境、人类活动、围封对榆树更新影响很大。还未见报道的问题有:个体成对现象;种子入侵草地空斑;风蚀和沙埋过程对榆树更新的影响;榆树更新的最佳围封年限。最后,指出榆树疏林研究的未来两大方向是榆树疏林与全球环境变化,榆树疏林与沙地植被恢复。

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.