南涧干热退化山地植被恢复的植物多样性变化

Change of Plant Diversity of Different Rehabilitated Communities on Degraded Mountainous Area of Dry-hot Valley in Nanjian

对20世纪90年代初期在南涧县城后山干热退化山地上营造的五种不同人工植物群落与未经改造次生植被的物种组成与结构进行了调查,采用生物多样性指数和相似性指数对各个群落进行测度.结果表明,经过十几年的恢复和保护,各人工群落植物种数及耐荫种数均有增加,分别在54～29和7～4间,高于坡柳、黄茅草灌草坡(26种和2种).恢复群落的Shannon-Wiener指数、Simpson指数、Pielou均匀度指数和Margalef丰富度指数增加,其中乔木层Shannon-Wiener指数在0.15～1.45间;除桉树群落外灌木层Shannon-Wiener指数在0.91～0.76间,均明显大于坡柳、黄茅草灌草丛(0.44);草本层Shannon-Wiener指数在0.39～1.49间,除桉树群落和新银合欢群落外也均有增加.恢复群落物种组成与结构逐渐向良性方向发展.然而,一些引进植物如山毛豆(Tephrosia caudida)在本地区早期阶段生长迅速并能够快速郁闭,为乡土植物生长创造了条件,但因自我更新能力差,已出现衰退现象,因此,应该加强人工群落保护和后续抚育管理,促进区域生态环境改善和良性发展.

Plant species diversity of revegetation communities rehabilitated at the beginning of the 1990s and local secondary shrub community on degraded mountainous area of dry-hot valley in Nanjian was studied in 2003. The results showed that number of plant species （29～54） and shade-tolerant species （4～7） of rehabilitated communities had both greatly increased in comparison with the local shrub community （26 and 2） after a rehabilitation period of more than ten years. Shannon-Wiener index, Simpson index, Pielou evenness index and Margalef richness index of the rehabilitated communities had also greatly increased. The values of Shannon- Wiener index of tree layer were 0.15～1.45, and that of shrub layer of the rehabilitated communities （0.91～ 0.76） were higher than the local shrub community （0.44） except Eucalyptus community . That of grass layer of the rehabilitated communities were 0. 39～ 1. 49, they all had greatly increased except Eucalyptus community and Leucaena glauca community. There has be a tendency towards good development in the species composition and structure of the rehabilitated communities. However, there is a problem that some introduced leguminous plant species such as Tephrosia candida have declined in rehabilitated communities, because it can not self producing influenced by low air temperature and moisture in reproductive stage, although it grew rapidly during the early stage. The conservation of revegetation and the follow-up management are more important in the rehabilitated area.