长久以来，化感（生物产生化学物质从而影响另一个生物；Fig. 1）被认为能够影响植物个体表现、群落结构与植物入侵。近期中科院东北地理所与农业生态研究所与德国康斯坦茨大学等单位合作搜集了384项实验的数据，并首次对化感作用进行了整合分析。结果表明，化感使植物的表现平均降低25%,但是研究间的异质性很高。例如不同实验方法测得的化感作用不同：与植物浸出液相比，植物残余物的抑制作用较强，而化感植物土壤的抑制作用较弱（Fig. 2）。化感的抑制作用随着物种之间进化距离（phylogenetic distance）的增加而增强，并且，已归化外来植物的浸出液对本地植物的抑制作用强于本地植物的浸出液 （Fig. 3）。本研究表明化感作用确实可以促进外来植物的成功入侵，而植物进化距离与化感作用的关系表明了化感能促进近缘种的共存（convergence）或促进单物种在群落中占主导优势。在文章的最后，我们还就化感的促进作用，土壤微生物对化感的影响，测试植物的重要性，以及化感的生态与进化意义进行了讨论，希望给未来的化感研究提供一些线索。
Figure 1 The different release pathways and effects of allelochemicals. The allelopathy plant (left) can release allelochemicals through four pathways (black arrows): leaching by rain (P1), decomposition of plant residues (P2), exudation from roots (P3) and volatilisation (P4). The allelochemicals can affect the test plant directly (red arrows) or indirectly through their effect on soil biota (dashed red arrows). Soil biota can also affect allelochemicals, such as through conversion or degradation of allelochemicals.
Figure 2 Effects of different aspects of study design on allelopathy. (a) Effects of the type of method (orange), the type of performance measure (blue) and the experimental environment (green) on allelopathy. (b) Effect of study duration on allelopathy. (c) Effect of the concentration of leachates on allelopathy. In (a) for each category (parameter), the posterior distribution is plotted with the mean and 95% credible interval. The text on the right displays the mean, 95% credible interval (CI), and the number of observations (obs) and papers. An asterisk indicates a significant difference between the level of interest and the reference level. In (b) and (c), curves of the estimated effects are shown with their 95% credible intervals. Negative values of the effect size (ln RR) indicate that allelopathy inhibits plant performance.
Figure 3 Effects of evolutionary history on allelopathy. (a) Effect of phylogenetic distance between allelopathy and test species on allelopathy. The curve of the estimated effect is shown with its 95% credible interval. (b) Effects of origin of allelopathy and test species on allelopathy when tested with the leachate method. Effects of native, non-naturalised alien and naturalised alien allelopathy species are shown in dark blue, light blue and orange. For each category (parameter), the posterior distribution is plotted with the mean and 95% credible interval. The text on the right displays the mean, 95% credible interval (CI), and the number of observations (obs) and papers. Negative values of the effect size (ln RR) indicate that allelopathy inhibits plant performance. An asterisk indicates significant difference between reference level (native on native) and the other.
该研究成果于近期发表在国际生态学Top期刊Ecology Letters上。本研究第一作者为张致杰博士，通讯作者为刘艳杰研究员。相关论文信息：Zhang Z, Liu Y*, Yuan L, Weber E, van Kleunen M (2020) Effect of allelopathy on plant performance: a meta-analysis. Ecology Letters, doi: 10.1111/ele.13627.
