不同入侵程度紫茎泽兰碳氮磷生态化学计量特征研究

紫茎泽兰(Ageratina adenophora)是一种生态危害性较大的入侵植物。为探讨不同入侵程度下紫茎泽兰的化学计量特征,进一步揭示其营养策略与入侵机制,该研究以紫茎泽兰及其本土伴生种条叶猪屎豆(Crotalaria linifolia)为对象,测定研究了轻度入侵、中度入侵和重度入侵下紫茎泽兰根、茎、叶中碳(C)、氮(N)、磷(P)化学计量特征与其入侵地土壤养分状况,并进一步比较了紫茎泽兰和条叶猪屎豆的C、N、P化学计量特征。结果表明:(1)3种入侵程度下,紫茎泽兰叶N、P含量均显著大于根和茎N、P含量,将更多的N和P分配至叶,增加资源获取,以利快速生长。(2)3种入侵程度下,紫茎泽兰茎N:P<根N:P<叶N:P,且茎N:P在中度入侵下显著大于轻度入侵,在入侵过程中其茎呈现出较高的生长速率,可促进其获取更多环境资源,增强生长竞争优势。(3)与本土种条叶猪屎豆相比,紫茎泽兰具有更高的根P、茎P含量,根和茎C:P、N:P均显著小于条叶猪屎豆,各器官C:N均显著大于条叶猪屎豆,显示出较高的养分利用效率及较低的资源需求量。(4)紫茎泽兰茎C和叶C、茎N和叶N均呈显著正相关,茎C:P与根C:P存在极显著负相关,说明对能量和资源的分配在生长和贮存之间存在权衡。研究认为,紫茎泽兰在入侵过程中采取增加地上部分的资源分配与利用以利于快速生长,同时具有较高的资源获取能力及较低的资源需求量,进而提高竞争能力,成为一种重要的入侵策略,促进其成功入侵。

Ecological stoichiometric characteristics of carbon, nitrogen and phosphorus in different invasition degrees of Ageratina adenophora

Ageratina adenophora is an invasive plant with great ecological harm. In order to explore the stoichiometric characteristics, nutritional strategy and successful invasion mechanism of A. adenophora with different degrees of mild invasion, moderate invasion and severe invasion, we measured carbon(C), nitrogen(N), phosphorus(P)contents and their stoichiometric characteristics of soils, plant nutritive organs and comparing these with a coexisting native species, Crotalaria linifolia. The results were as follows:(1)The contents of N and P in the leaves of A. adenophora were significantly greater than those in the roots and stems in the three invasive degrees, indicating that N and P elements were more allocated to the leaves to increase resource acquisition and rapid growth.(2)Stem N:P<root N:P<leaf N:P of A. adenophora in the three invasive degrees, and the stem N:P of moderate invasion was significantly higher than that of mild invasion, suggesting that the greatest relative growth could occur in stem during invasion to absorb more resources and increase competitiveness.(3)P contents in stems and roots, C:N in nutritive organs of A. adenophora were significantly higher than that of C. linifolia. C:P, N:P in both stems and roots of A. adenophora were significantly lower than that of C. linifolia, implying that A. adenophora had strong utilization but low requirements of resources.(4)Significant positive correlations were found between stem C and leaf C, and between stem N and leaf N of A. adenophora, while there was a significant negative correlation between stem C:P and root C:P, indicating a trade-off between growth and storage of energy and resource allocation. The study suggests that A. adenophora may increase the allocation and utilization of the aboveground resources during invasion, which is conducive to rapid growth, and at the same time, it has higter utilization but lower requirements of resource demand, which all contribute to increase competitiveness and successful invasion of A. adenophora.