金沙江流域水库消落带优势植物生态位及种间关系

Niche and interspecific associations of dominant plants in the water-level-fluctuating zones of the reservoirs in the Jinshajiang River watershed

近年来水库消落带植被恢复愈发引起关注,消落带植被在固岸护坡、水土保持和截污过滤等方面发挥着重要作用。然而金沙江流域作为我国最大的水电基地,由于地处偏远,现有研究较少,因而对其水库消落带适生植物及其种间关系尚未明确。通过结合生态位理论和种间关系分析方法,包括生态位测定、方差比率法、χ^(2)检验、联结强度系数A C、种间关联指数O I、Pearson相关检验和Spearman秩相关检验等,揭示金沙江水库消落带优势植物的生态适应性、种间内在联系以及群落演替现状,并在此基础上,将优势植物划分了3种生态种组,为本区域消落带适生植物的筛选及其科学配置提供参考。结果表明:1)金沙江流域水库消落带共记录植物19科36属37种,频度≥20%的优势物种为狗牙根(Cynodon dactylon)、酸模叶蓼(Polygonum lapathifolium)、钻叶紫菀(Symphyotrichum subulatum)、牛筋草(Eleusine indica)、莲子草(Alternanthera sessilis)、苘麻(Abutilon theophrasti)、土荆芥(Chenopodium ambrosioides)和苍耳(Xanthium sibiricum)。其中,狗牙根的重要值和生态位宽度最大,占绝对竞争优势。2)整体来看,消落带优势植物的生态位相似性和重叠度较小,对资源利用的相似程度低,优势植物生态位分化程度较高。3)优势植物的总体联结性表现为不显著负联结,χ^(2)检验、Pearson相关检验和Spearman秩相关检验结果均显示负联结比例大于正联结,种间联结性较弱,群落整体稳定性较差。结合生态位和种间关系研究结果,推荐以上8种优势植物为先锋物种,根据划分的3种生态种组沿水位梯度进行配置试验,使植物种间关系向着更协调的方向发展,促进消落带植被自然修复进程。

With the completion and operation of several world-class high dam reservoirs in the Jinshajiang River watershed,the high sensitivity and vulnerability of the reservoir water level fluctuating zone(WLFZ)ecosystem have become increasingly prominent.How to restore the vegetation in the WLFZ is of great significance to protect the stability and diversity of ecological functions and maintain a critical cycle of the ecosystem.With ecological niche theory and interspecific relationship analysis methods,including ecological niche determination,variance ratio method,χ^(2) test,association coefficient A C,Ochiai index O I,Pearson correlation coefficients and Spearman rank correlation coefficients,intrinsic interspecific linkage,ecological adaptability and community succession status of dominant plants in the WLFZ of the Jinshajiang River Reservoir were revealed.The dominant plants were classified into three ecological species groups to provide reference for suitable plants and their scientific allocation for ecological restoration in the WLFZ.The results show that:1)A total of 37 plant species belonging to 19 families and 36 genera were recorded in the reservoir WLFZ of the Jinshajiang River watershed,and the dominant species at a frequency of≥20%being Cynodon dactylon,Polygonum lapathifolium,Symphyotrichum subulatum,Eleusine indica,Alternanthera sessilis,Abutilon theophrasti,Chenopodium ambrosioides and Xanthium sibiricum,in which C.dactylon had the greatest importance value and ecological niche width,dominating the absolute competition.2)The overall similarity and overlapping in ecological niches of dominant plants in the WLFZ are small,and the similarity in resource use is low,indicating high degree of ecological niche differentiation between dominant plant species.3)The overall connectivity of dominant plants shows non-significant negative associations,and the overall stability of the community is poor.Theχ^(2) test,Pearson correlation coefficients and Spearman rank correlation coefficients all showed low significance and weak interspecific linkages.Based on the results of the ecological niche and interspecific relationship studies,eight dominant plant species are recommended as pioneer species,and the three ecological species groups are allocated along the water level gradient according to the delineation,so that the interspecific plant relationships evolve towards harmony and benefit the natural restoration process of the vegetation in the WLFZ.