入侵植物印加孔雀草在不同生境的种群构件生物量及其分配特征

印加孔雀草是中国西藏新近入侵种,其危害已初见端倪,但我国鲜有对其入侵机理的研究。为探究印加孔雀草在异质环境下的种群构件生物量及其分配特征,进一步深入了解其生存策略和易入侵生境。该研究在菜园、果园、路边、荒地和河滩等五种典型入侵生境内对其花果期的种群构件生物量进行了测定和分析,计算了表型可塑性指标值。结果表明:(1)印加孔雀草种群各构件生物量的基本规律为茎>花果>叶>根,在路边最大,菜园最小,两地间各值均存在显著差异(P<0.05)。(2)印加孔雀草各构件生物量的总变异系数(CV)和可塑性指标(PI)的均值分别为46.93%和61.44%。(3)印加孔雀草繁殖与营养构件生物量比的关系为荒地>路边>果园>河滩>菜园,根冠比表现为菜园>荒地>河滩>路边>果园。(4)印加孔雀草各构件之间、各构件与总生物量间都存在显著的正相关关系,体现了其整体协调的生存策略。上述结果表明,印加孔雀草能通过各构件生物量的调整来适应异质生境,具有较高的可塑性;高繁殖输出和对异质环境的适应性可能是其成功入侵的重要原因。

Module biomass and allocation characteristics of invasive plant Tagetes minuta populations in different habitats

Tagetes minuta, as a newly invasive species in Tibet of China, its damage is beginning to appear. However, there are few studies on its invasion mechanism in China. In order to explore the biomass and its allocation characteristics of population modules of T. minuta in heterogeneous habitats, and to further understand its survival strategies and invasive habitats, we determined and analyzed the biomass characteristics and calculated the index values of phenotypic plasticity of the population modules in the flowering and fruiting stages of the T. minuta in five typical invasive habitats, including vegetable garden, orchard, roadside, wasteland and riverside. The results were as follows:(1)The basic law of biomass of module in T. minuta population was stem > flower and fruit > leaf > root. The biomass of each module was the largest in the roadside and the smallest in the vegetable garden, and there were significant differences between these two habitats(P<0.05).(2)The total coefficient of variation(CV)and phenotypic plasticity index(PI), based on maximum and minimum means of each module were 46.93% and 61.44%, respectively.(3)The relationship between biomass ratio of reproductive module and nutrient module of T. minuta was wasteland > roadside > orchard > riverside > vegetable garden, and the root-shoot ratio was vegetable garden > wasteland > riverside > roadside > orchard.(4)There were significantly positive correlation between biomass of different modules, between biomass of different modules and total biomass, which showed its ensemble and consistent strategy of survival. The above results indicate that T. minuta can adapt to heterogeneous habitats by adjusting the biomass of each module, and thus has a strong phenotypic plasticity. High reproductive output and adaptability to heterogeneous environments may be the important reasons for its successful invasion.