围栏封育对黄河源区退化高寒草地植被组成及生物量的影响

在黄河源区-青海省果洛藏族自治州玛沁县选取4个不同退化程度的天然草地,以围栏内封育和围栏外自由放牧草地作比较,采用样方法调查草地围栏内外的群落结构特征和草地初级生产力生物量,并通过计算地上与地下生物量比值以及植物群落干鲜比来评价围栏封育的效果。结果表明:不同退化程度围栏内外的植被组成存在显著差异;随着退化程度的加剧,植物群落的盖度、高度以及多样性指数有下降趋势,且围栏内的盖度、高度及多样性指数均大于围栏外的;植物群落高度、盖度、地上生物量和生物量干鲜比随着退化程度加剧有减小的趋势。围栏封育有利于改善青藏高原退化高寒草地的植物群落结构,提高草地植物群落的盖度和生物量,促进其恢复演替。

Effect of Grassland Enclosure on Vegetation Composition and Production in Headwater of Yellow River

The plant community structure and primary production of the alpine grasslands under different degradation degrees were investigated in Maqin County of Qinghai Province,the headwater area of Yellow River.The structure of the plant community had significant variation relating grassland degradation with fencing.The coverage and height of plants inside fences were higher than those outside fences and declined with the increase of degradation degrees.Similar results were found for the plant diversity index.The aboveground biomass,coverage and height of the grassland along degradation gradients showed a declining trend.These parameters were significantly higher in the fenced grasslands than the unfenced ones.Aboveground biomass/underground biomass ratios of the grassland were decreased by degradation and increased by fencing.The ratios of dry to fresh weight of aboveground biomass declined with the increase of degradation degree and increased after fencing.It can be concluded that grassland enclosure is a feasible approach to restore grassland vegetation in the headwater areas of the Qinghai-Tibetan Plateau.Plant cover,plant biomass and species biodiversity can be used as indicators to assess grassland restoration intervention.