青藏高原高寒草地的退化及其恢复

述评了青藏高原高寒草地的退化及其恢复治理。青藏高原高寒草地是世界著名的放牧生态系统之一,严重的草地退化正在危及着高原的生态环境,三分之一的高原草地已经退化。"黑土滩"退化草地,作为高原上严重退化草地的一种特殊形式,已经从上世纪80年代的396.57×104公顷增加到90年代的703.19×104公顷。然而,迄今为止青藏高原高寒草地的退化趋势仍然没有改变。研究表明高寒草地的退化是一种连续的过程,遵循如下的次序:未退化草地-轻度退化草地-中度退化草地-重度退化草地。高寒草地退化的原因包括人为和自然因素的影响。人为因素包括季节性过度放牧、盲目开垦草地、采矿、道路建设、开矿采金等等。自然因素包括气候变暖变干、鼠虫害影响、风和水的侵蚀、草皮层冻融等等。需要强调的是在许多高原地区过度放牧总是草地退化的主要原因。面临着这个严峻的形势,许多科学家和当地政府从20世纪80年代起充分重视退化草地恢复,以达到保护天然牧场和生态环境的目的。基于恢复生态学的原理,针对退化草地的恢复,一些有效的实践及综合治理的对策已经在青藏高原得到发展。退化草地恢复的实践包括围栏封育、松耙、补播、施肥、草皮移植、啮齿类动物及杂草的控制、选择和筛选优良牧草、建植人工半人工草地、优化家畜结构等等。基于这些实践,退化草地的综合恢复,人工草地建植及持续利用在青藏高原高寒草地分布区应进一步加强。

Alpine Grassland Degradation and Its Restoration on Qinghai-Tibet Plateau

We reviewed alpine grassland degradation and its restoration on Qinghai-Tibet Plateau in China.The alpine grassland of Qinghai-Tibet Plateau is one of the world’s most remarkable grazing land ecosystems.Serious grassland degradation is endangering eco-environment of the plateau.There is about 0.50×108 hm2 degraded grassland, one third of all grassland in the plateau.The area of"Black Soil Type"degraded grassland,a special form of severe degraded grassland in the plateau,is increased from 396.57×104 hm2 in 1980s to 703.19×104 hm2 in 1990s.However, the degrading trend of grassland is still not reversed in the plateau.The studies suggested that alpine grassland degradation was a process of reversing succession with following order:non-degraded grassland-lightly degraded grassland- moderately degraded grassland-heavily degraded grassland.Alpine grassland degradation was caused by the integrated effect of anthropogenic and natural factors.Anthropogenic factors include seasonal over-grazing,blind reclamation of grassland,mining,road construction,gold and sand collection,etc.Natural factors include climate warming and drying,rodent and insect pest,wind and water erosions,freeze-thaw striping of sod layer,etc.It needs to emphasize that over-grazing is always the principal cause of grassland degradation in many places of the plateau.Facing this serious situation,many scientists and local government paid full attention to grassland degradation in order to restore degraded grassland,protect natural pasture and eco-environment since 1980s.Utilizing the successional process and successional mechanism of alpine grassland,based on the principles of restoration ecology,some effective practices and integrated countermeasures for restoration of degraded grassland have been developed in Qinghai-Tibet Plateau.Practices of the degraded grassland restoration include as followed,such as fencing,scarification,plowing,reseeding,fertilizing, turf transplant,rodent and ruderal control,selection and screening of grassland forages,construction of planted and semi-planted grassland,rational management of alpine grassland and optimizing structure of livestock as well.Based on these practices,integrated restoration of degraded grassland,revegetation and sustainable utilization should be developed and implemented on Qinghai-Tibet Plateau.