干旱、半干旱地区天然草原灌木及其肥岛效应研究进展

摘要

灌丛可以改变局部的生态小环境，使其周围植物生物量、植物组成、植物化学成分、土壤中大量营养元素和微量营养元素产生变异，将养分集中于灌木灌丛下，改变其周围的局部小环境，影响灌丛下的植被和土壤养分，称作灌丛肥岛效应。灌丛因截留水分、养分及遮阴等作用使其周围局部土壤和植被环境发生变化，导致其树冠下养分和水分聚集，土壤养分相对周围空地更肥沃。探讨干旱和半干旱地区天然草原的灌丛化过程及其生态学效应，了解其对荒漠草地恢复过程的作用，减缓土壤侵蚀和草地生产力下降，对植被的演替和恢复重建等都有重要的生态学意义，并为防治干旱半干旱荒漠生态地区土地退化提供理论依据。%Shrubs can change the local ecological environment,which in turn impacts on the surrounding plant biomass,plant composition,plant chemical composition,and macro-and micronutrient elements in the nearby soil.Shrubs can change the local micro-environment in ways which affect the spatial distribution and circulation of nutrients,and may concentrate nutrients under the shrub canopy or enhance moisture retention.Such pat-ches displaying enhanced moisture and nutrient retention and shade effects relative to the surrounding space are known as the shrub fertile islands.Here we discuss the ecological impact of shrubs in natural arid and semi-arid grassland areas and their role in the desert grassland restoration process,reduction of soil erosion and associat-ed grassland productivity decline.The importance of shrubs and their ecological significance for vegetation suc-cession and restoration and reconstruction is discussed,and a theoretical basis for prevention and control of land degradation in ecologically fragile regions is provided.