克隆整合对异质性土壤养分生境下薇甘菊生长的影响

Effects of clonal integration on the growth of Mikania micrantha in habitats with heterogeneous nutrient availability

环境资源的异质性在自然界中普遍存在。克隆植物能通过克隆整合较好地适应异质性生境。本文以海南外来强入侵性植物薇甘菊为材料,通过温室盆栽试验,研究克隆整合对异质性土壤养分生境下薇甘菊克隆片段生长的影响。结果表明:在养分异质下,克隆整合显著提高了低养分斑块分株的生物量,但同时降低了高养分斑块分株的生物量,对克隆片段总体的生长无显著影响,且这一结果不受资源输送方向的影响。克隆整合对薇甘菊克隆分株的光合速率和比叶面积影响较小,但当近端分株处于高养分条件时,其改变了克隆分株的根冠比。这些结果指示:克隆整合有利于异质性土壤养分条件下薇甘菊对低养分斑块的占领。因此,克隆整合可影响薇甘菊对资源异质性生境的入侵能力,它使薇甘菊能够扩展到低养分斑块,从而提高其入侵扩散能力。

Heterogeneity in resource availability is common in nature. Clonal plants can adapt to habitats with heterogeneous nutrient availability by clonal integration. We conducted a pot experi- ment to examine the effects of clonal integration on the performance of a strongly invasive plant in Hainan, Mikania micrantha, growing in habitats with heterogeneous nutrient availability. The re- sults demonstrated that when nutrient availability was heterogeneous, clonal integration increased the biomass of the ramets growing in patches with low nutrient availability, reduced the biomass of the ramets growing in patches with high nutrient availability, and did not significantly change the biomass of the whole clonal fragments. This result was not affected by the direction of resource transportation. Clonal integration did not significantly change the ramets＇ photosynthetic rate and specific leaf area, but when the proximal ramets grew under high nutrient conditions, clonal inte- gration changed the root/shoot ratio of the clonal ramets. These results indicate that clonal inte- gration benefits the growth of M. micrantha ramets growing in patches with low nutrient availabili- ty. Therefore, clonal integration is an important growth strategy for M. micrantha to adapt to envi- ronments with heterogeneous resource availability, and it can allow M. micrantha to expand to low nutrient patches, improving the plant＇ s invasion and expansion capacity.