西南干热河谷植物群落稳定性及其评价方法

Stability and evaluation methods of plant communities in the dry-hot valleys of Southwest China

干热河谷是我国西南地区高山峡谷地貌下形成的一种特殊的生境类型;植物群落稳定性研究对揭示该区域植物群落动态特征和变化规律具有重要理论和实践意义.采用植物多样性与群落结构特征指标、土壤肥力指标、土壤微生物与酶活性指标以及群落优势种幼苗更新特征与凋落物生物量指标等反映群落稳定性的数量特征指标构建植物群落稳定性评价模型.利用改进的层次分析法确定指标权重,根据历年来西南干热河谷区相关研究结果确定各指标基准值,采用极差法对各指标进行标准化处理,通过综合评价指数法计算群落稳定性.同时,采用该评价方法体系评价元江干热河谷不同类型人工恢复植物群落以及虾子花(Woodfordia fruticosa)天然次生灌草丛群落的稳定性.结果表明,元江干热河谷不同类型植物群落稳定性综合评价指数在0.9-2.0之间.其中,久树(Schleichera trijuga)人工恢复植物群落稳定性指数最高(1.93),是该区域唯一超过天然次生植被虾子花灌草丛群落稳定性(1.53)的人工恢复植物群落.其他植物群落中,印楝(Azadirachta indica)群落和铁刀木(Cassia siamea)群落稳定性居中,综合评价指数均高于1.0;清香木(Pistacia weinmanniifolia)群落和车桑子(Dodonaea viscosa)群落稳定性相对较低,分别为0.99和0.93.采用该评价体系可以直观地量化群落内各评价指标以及群落稳定性综合评价指数在西南干热河谷区不同类型植物群落中所处的位置和状态;评价结果与群落外貌、群落生长概况以及群落内部环境状况基本一致,较好地反映了群落稳定性的实际情况.另一方面,适宜树种的选择在干热河谷人工植被恢复过程中起着非常关键的作用;久树、印楝和铁刀木应是元江干热河谷人工植被恢复较适宜的树种,经过一段时间的生长能够形成较稳定的植物群落.(图6表7参133附表4)

Dry and hot valleys are special type of habitat formed under alpine gorges in Southwest China.Understanding plant community stability can help determine what drives changes in community characteristics in this area.In this study,a plant community stability evaluation model was established using quantitative characteristic indicators reflecting the stability of the community,such as plant diversity,community structure,soil fertility,soil microorganisms,soil enzyme activity,seedling regeneration characteristics,and litter biomass of dominant species in the community.An improved analytic hierarchy process was used to determine indicator weights and benchmark values of each indicator according to relevant research results of dry and hot valleys in Southwest China.The range method was used to standardize each indicator,and community stability was calculated using the comprehensive evaluation index method.The stability of different types of artificially restored plant communities as well as Woodfordia fruticosa natural secondary shrub and grass communities in dry and hot valleys of the Yuanjiang River were evaluated using the evaluation method system.The comprehensive evaluation index of stability of different types of plant communities in the dry and hot valleys of the Yuanjiang River ranged from 0.9–2.0.Among them,the stability index of the artificially restored Schleichera trijuga plant community was the highest(1.93).This community was the only artificially restored plant community that exceeded the stability index of W.fruticosa natural secondary shrub and grass communities(1.53).The stabilities of the Azadirachta indica and Cassia siamea communities were average,with a comprehensive evaluation index higher than 1.0.The stabilities of the Pistacia weinmanniifolia and Dodonaea viscosa communities were relatively low(0.99 and 0.93,respectively).The position and status of each evaluation index and comprehensive evaluation index of community stability in different types of plant communities in the dry and hot valleys of Southwest China could be visually quantified using this evaluation system.The results of this evaluation were consistent with the appearance,growth profile,and internal environmental conditions of the community,which better reflected actual community stability.The selection of suitable tree species plays a key role in the restoration of artificial vegetation in dry and hot valleys.Schleichera trijuga,A.indica,and C.siamea are suitable tree species for artificial vegetation restoration in the dry and hot valleys of the Yuanjiang River.They can form relatively stable plant communities after a short period of growth.