岷江干旱河谷主要草本种群生态位研究

Characteristics of main herb populations in the arid valley of the Minjiang River

在对岷江干旱河谷植被及其环境因子系统取样调查的基础上,研究了20种主要草本种群在土壤水分、全N、速效P、速效K和pH 5个资源维上的生态位特征。绵枣儿、铁扫帚、翻白委陵菜、黄背草、密生苔草的生态位宽度较高,对环境有较强的适应能力,形成了该地区的优势种群;猪毛莱、紫花野茅,歧茎蒿、虱子草等种群的生态位宽度较小。生态位宽度较小的物种并非就不是群落的优势种,取决于种群分布的范围和分布的均匀程度。种群在各个资源维上的生态位宽度表明对不同资源空间的利用能力和适应性不尽相同。各个资源维上所有种群生态位宽度和的大小依次为土壤含水量>pH>速效K>全N>速效P,表明物种对速效P资源的利用能力较低,对土壤含水量的利用能力较高,草本物种对水分资源的利用能力高于灌木物种。

Based on a field investigation, the characteristics of herb populations niche in the arid valley of the Minjiang River were charactorized, soas to provide a scientific base for vegetation restoration and management. Niche breadths and overlaps of 20 main herb populations along gradients of soil moisture,soil pH,available K,available P,and total N were analyzed using Levins and Schoener indices. Scilla scilloides,lndigofera bungeana,PotentiUa leuconota, Themeda triandra,Carex crebra have higher niche breadth and adaptability to environment, which are the dominant species and play vital roles in maintaining the diversity and stability of plant community;niche breadth of each population in different resource dimension shows that different population has different ability of using resources, so they have different ecological adaptability. The sum of niche breadth of all populations in different resource dimension is as thefollowing：soil moisture 〉 soil pH 〉 available K 〉 total N 〉 available P. It indicates that the ability of populations using available P is lower than that of soil moisture;Not all species with low niche breadth were not dominant species in the communities ,which depend on the range and evenness of species distribution. The ability of herb populations adapting arid environment is higher than that of shrub populations.