新疆准噶尔盆地荒漠草地水源圈植物群落退化格局

Degradation pattern of desert steppe plant community around a piosphere in Junggar Basin of Xinjiang

游牧民定居放牧是目前主要的放牧方式,导致水源圈在中国北方干旱半干旱区草场上普遍存在。2014年5月底至6月初,在新疆北部荒漠草地上,以一个典型的牧场水源点为中心,在8个方向上设置50、100、200、400、800和1200 m共6个采样距离进行植物群落调查取样。通过分析植物群落的组成、物种重要值、丰富度以及群落的盖度、高度和地上生物量的变化特征,期望为荒漠草地退化生态系统的恢复和可持续管理提供科学依据。结果表明:随着与水源点距离的减少、放牧强度的增加,荒漠草地植物群落特征呈现明显梯度变化,建群植物博洛塔绢蒿优势度逐渐降低,1年生植物优势度逐渐增加;植物群落、多年生草本植物和1年生草本植物的物种丰富度逐渐增加;群落总盖度逐渐降低,与建群植物博洛塔绢蒿的盖度显著正相关。1年生植物和有毒植物骆驼蓬在水源点附近优势度增加,说明放牧导致水源点附近地上植物群落趋于退化。因此,在这一地区开展游牧民定居导致水源圈大量出现,可能加剧荒漠草地的退化。

As the primary mode of grassland utilization, settled grazing makes the piospheres widespread in arid and semi-arid grasslands of China. During the end of May to early June, 2014, radiating from a watering point, 8 sampling transects were established at a set distance gra- dient of 50, 100, 200, 400, 800 and 1200 m following 8 orientations in Junggar basin of Xin- jiang, China. The effects of piosphere were studied by analyzing the composition, species impor- tance value, species richness, vegetation cover, height and aboveground biomass of the plant community, aiming to provide scientific basis for the restoration and sustainable management of the desert steppe. The results showed that, with the decrease of distance from the watering point, the grazing intensity increased, and the community characteristics varied significantly. Palatable Seriphidium borotalense is more abundant and dominant in areas distant from watering point, and the highly disturbed area adjacent to watering point was dominated by annuals and poisonous Pe- ganum harmala. The species richness of the community including perennials and annuals in- creased with decreasing distance from the watering point, while the vegetation cover decreased, which was notably driven by S. borotalense cover. The flourish of annual plants and poisonous P. harmala in the vicinity of the watering point indicated the degradation of the plant community ap- proaching to the watering point. The implementation of the nomadic settlement project may pro- duce more piospheres, which may accelerate the degradation process of the desert steppe.