增温对入侵植物马缨丹生物量分配和异速生长的影响

Effects of warming on the biomass allocation and allometric growth of the invasive shrub Lantana camara

气候变暖已是不争的事实。外来入侵植物随着温度升高有可能作出积极的响应,采取有效策略来扩大入侵范围,造成更大的危害。以世界性杂草马缨丹(Lantana camara)为研究对象,对不同温度处理下(22、26℃和30℃)的生长和分配特征及构型效应进行对比研究,并借助异速生长分析方法,对不同温度下马缨丹幼株各构件生长关系进行分析。结果表明:随着温度升高,马缨丹幼株减少了对地下生物量的分配,地上部分生物量投资的增加主要表现在对茎的投资上,并利用有限的叶生物量投资扩大叶面积,即在高度和广度两方面都增加了对光能的获取。这些响应有利于其同化作用的增强从而提高竞争力,表明温度增加会增强马缨丹的入侵力,这也是马缨丹在全球气候变暖背景下扩大其分布范围的有效策略。

The earth＇s temperature is increasing, and species differ in their response to climate change depending on their environmental niche properties and physiological characteristics. As adaptable species, invasive plants may be favored to expand their geographical distribution, thus result in more harm. The focal species of this study was the highly invasive shrub, Lantana camara （Verbenaceae） , occurring mostly between the latitudes of 35°N and 35°S. L. camara has been identified as one of the 100 world＇s most invasive alien species, as it has caused major problems, including decreasing native species diversity, reducing soil fertility, allelopathic alteration of soil properties, and alteration of ecosystem processes. Based on CLIMEX simulations, its potential distribution will expand in new areas under current and future climate scenarios. However, there is limited information on biomass allocation and allometric growth under different temperatures of this species. In this study, we conducted a pot experiment in which branch cuttings were grown at three different temperatures （22, 26, and 30℃ ） to explore the responses of L. camara to climate warming. The morphological variables, including biomass of different growth components, plant height, basal diameter of shoot, volume of root and shoot, and area of leaves were measured. The root-shoot ratio, stem-leaf ratio, leaf mass per area, petiole mass per length, and stem mass per length were calculated. The biomass allocation and configuration effect of L. camara under different temperatures were compared. Based on allometric scaling analysis, the allometric growth of L. camara growing in different greenhouses with different temperatures were studied. From the experiment, significant correlations and allometric relationships were found among growth components. We found that with increasing temperature, root biomass decreased, whereas shoot biomass and leaf area increased. The results suggested that L. camara increased its biomass investment of stems and expanded its leaves as much as possible, even with the decrease of leaf biomass allocation under higher temperatures, which enhances light capture and assimilation under warming. We concluded that L. camara effectively adapted growth strategies to benefit from global warming to compete with native species and improve its invasiveness, which would effectively expand its distribution.