晋西黄土区极陡坡植物群落特征及自然恢复困难度分析

Vegetation Community Characteristics and Difficulty Degree of Vegetation Natural Restoration on Extremely Steep Slopes of Loess Area in Western Shanxi Province

为了解黄土沟壑区极陡坡承载的植被类型及植被自然恢复状况,以晋西黄土区蔡家川流域内的极陡坡为研究对象,采用时空互代的方法研究了群落物种组成及多样性的时空变化,并对演替进程中植被恢复的困难程度进行评价。结果表明：晋西黄土沟壑区内极陡坡的主要植被类型为灌木和草本,随着演替阶段由稀疏灌木及草坡群落向乔灌草群落的递进,群落物种丰富度提高,物种组成更为均衡,多样性水平随演替进程先增加后略减,有利于群落朝着更为稳定的方向发展。方差分析结果表明,35°-55°极陡坡之间植被多样性整体差异不显著（P〉0.05）,均一性较高,55°以上的地形植被分异明显。运用因子分析综合评价的方法,可将植被自然恢复困难程度划分为容易恢复、一般、较难、极困难恢复4个等级,一般和容易恢复的样地可采取自然修复的方式恢复植被,而对于较难和极困难恢复的样地,则应采取相关人工促进恢复措施,才有可能取得植被恢复的成效。

In order to investigate the vegetation types and natural restoration condition of extremely steep slopes in loess hilly area, we selected the extremely steep slope of the Caijiachuan in the loess area of western Shanxi Province as the research object, and studied the temporal and spatial changes in species composition and diversity of vegetation community by using the method of spatial sequence instead of time successional sequence. The difficulty degrees of vegetation natural restoration were also studied. The results indicated that. Herb and shrub were the main vegetation types in the extremely steep slope area. With the vegetation succession from sparse shrub and grass community to the arbor-shrub-grass community, vegetation community species richness increased, and the species composition become more balanced. Plant species diversity increased at first and then slightly declined with the succession process, which was beneficial to developing more stable community. Moreover, based on variance analysis, the vegetation diversity of 35° to 55° steep slopes showed no significant difference （P〉0.05） and high degree of homogeneity, while difference in vegetation of 〉55° steep slopes was obvious. By the use of factor analysis, difficulty degrees of vegetation natural restoration were classified into easy, normal, difficult and extremely difficult degree. The sampling plots with easy and normal degree of natural restoration could be restored by natural restoration, while those with relatively higher difficulty degree should apply the relevant artificial recovery measures to improve vegetation restoration.