伊洛河河岸带生态系统草本植物功能群划分

植物功能群是对环境有相同响应和对主要生态系统过程有相似作用的组合。伊洛河是黄河中游南岸的一条重要水系,其河岸带生态系统不同生境类型中草本植物优势种变化明显,能较好地反映出植被与环境的动态关系。根据调查结果,结合出现次数和重要值,选取27种优势种进行种间联结及相关性分析。以$2检验为基础,结合联结系数AC和共同出现百分率PC来测定草本层优势种间的联结性,根据优势种间的联结性及其在不同生境中的变化异同,以优势种为主体划分伊洛河河岸带生态系统中草本植物功能群。结果表明,对27种草本植物优势种共划分了5组功能群:"广布型"、"湿生型"、"中旱生型"、"农田逃逸型"和"入侵型"。表明以优势种为主体对伊洛河河岸带生态系统草本植物进行功能群划分可行性高,有较强的代表性。同一功能群物种间表现出显著正联结性,一起出现在同一生境下的几率较大,在长期的生长演化过程中,能够适应相似的资源环境且对干扰有相似的响应。伊洛河河岸带生态系统由于长期的自然和人为干扰,加上外来物种的入侵,河岸带生态系统的生物多样性和生态安全面临着严峻的挑战。

The classification of plant functional types based on the dominant herbaceous species in the riparian zone ecosystems in the Yiluo River

Plant functional groups(PFGs) are defined as groups of species that either exhibit the similar responses to environmental perturbations or have the similar effects on major ecosystem processes.Discussing the functioning and stability-maintaining mechanisms of the terrestrial ecosystems,the adaptations and responses of plants to environmental changes,as well as water and nutrient use efficiency from the plant functional group perspective have become a major research approach in ecosystem ecology.PFGs analysis is an effective approach to reduce the complexity of plant communities and to reveal the general patterns and processes in the riparian zone ecosystems.The Yiluo River is an important tributary of the Yellow River in the south side of the middle reaches of the Yellow River.The vegetation in the riparian zone ecosystem of the Yiluo River has been heavily impacted by human.Although the species richness is high in this area,the herbs are mainly composed of a small number of dominant species whose abundance vary significantly among different types of landscape elements.Highly responsive to the changes in environmental conditions,herbaceous plants are very useful to the study of vegetation-environment dynamics.Using community ecology techniques,we investigated plant assemblages of the dominant herbaceous species in the riparian zone ecosystem of the Yiluo River.We calculated importance values,which were used to identify dominant species.Then we calculated the frequency of occurence and importance values of 27 species and identified dominant species.x2 test,together with association coefficient(AC) and percentage co-occurrence(PC),were used to measure interspecific associations of the dominant herbaceous species.PFGs were defined according to the interspecific associations and the distribution of landscape elements of the dominant herbaceous species of the herb layer.Dynamics of these PFGs along the moisture and original destination were analyzed.The results of this study showed that,classifying PFGs according to the dominant herbaceous species is feasible in the studies of herbs in the riparian zone ecosystem plant assemblages,and PFGs defined in this way are representative.Five PFGs,each with its unique spatial distribution and morphological characteristics,were identified: "widespread type","wet type","middle-xeric type","farmland-escape type",and "invasion type".These PFTs appear to reflect vegetation-environment dynamics wel1.Taking Digitaria sanguinalis as an example,it is widely distributed in most habitat types of the riparian zone ecosystem.Therefore,we classified it as a widespread type.Alternanthera philoxeroides,with a strong adaptability and asexual reproduction ability,mainly distributed in the flood terrace shaping the film distribution pattern,is a typical invasive species.The same function group of species shows significant connection,occurring together more likely in the same habitat.In the long term growth evolution process,they can adapt to the similar resource and environment and have the similar responses to disturbance.Furthermore,due to the long term of natural and anthropogenic disturbance,together with the invasion of alien species,the biological diversity and ecological security of the riparian zone ecosystem in the Yiluo River is facing serious challenges.The problem of habitat fragmentation and biological invasion is serious in the Yiluo riparian ecosystems,and the local government should strengthen and improve the management of ecological safety.