土壤微生物对不同种源乌桕生长的影响

【背景】土壤微生物对植物成功入侵具有重要影响,研究中国本地土壤微生物对美国入侵种乌桕的净生长效应有利于进一步理解乌桕成功入侵的机理。【方法】以本地和入侵2个种源多个种群的乌桕为试验材料,通过对土壤进行灭菌处理,研究土壤微生物对不同种源乌桕幼苗生长的影响。【结果】土壤微生物对入侵种乌桕具有正效应,与本地种相比,入侵种乌桕幼苗总生物量、相对生长速度、根冠比以及总叶面积、叶面积比、比叶面积等生物学指标在新鲜土壤中均表现出明显优势。种源和土壤处理间存在交互效应的指标显示土壤微生物去除对入侵种乌桕的抑制作用更为明显。这一结果与土壤自然天敌逃逸假说相背,入侵种乌桕在一定程度上具有较本地种更强的土壤微生物利用能力,在非根际土壤微生物的作用下入侵种乌桕具有较强的生长能力和明显的竞争优势。【结论与意义】本研究证实土壤微生物可能对乌桕成功入侵具有不可忽略的作用。由于该试验在乌桕起源地进行,结合在乌桕入侵地进行的研究有助于进一步分析土壤微生物对入侵的贡献作用;研究土壤微生物与入侵植物的互作关系有助于对入侵物种进行准确预测和有效控制,减少生物入侵对生态系统功能的破坏。

Effects of soil biotic communities on the seedling performance of native and invasive provenances of Triadica sebifera

Background]Soil biota can have great impacts on the invasive success of exotic plants.An insight into the net effects of soil biota in its native range on seedling performance of native and invasive provenance of Triadica sebifera（Euphorbiales：Euphorbiaceae） would help to understand this plant species.Method]In a controlled greenhouse experiment in Nanjing Agricultural University,multiple populations of native and invasive T.sebifera provenances were grown in sterilized and non-sterilized soils to examine the effects of soil biota on their seedling performance.Result]The results indicated that soil biota exerted positive effects on invasive lines.Compared with the native provenances,morphological and physiological traits of the invasive populations（total biomass,relative height growth rate,root：shoot ratio,total leaf area,leaf area ratio and specific leaf area） expressed substantial advantage while they were grown in non-sterilized soils.The significant interactions between provenance and soil treatment on functional traits revealed much more distinct inhibition effects of soil biota sterilization on invasive relative to native T.sebifera provenances.Conclusion and significance]Overall,the results of this study demonstrated that the invasive T.sebifera did not suffer from belowground natural soil enemies in its native range,which is contrary to the enemy release hypotheses prediction.In order to draw a full picture of the role played by soil biota in the successful invasion of T.sebifera,further parallel studies are highly needed in the invasive range of T.sebifera.Understanding the interaction mechanisms between soil biota and invasive plants would enable us to efficiently predict and control invasive species,so as to avoid ecosystem functions destroyed by invasive plants.