Yu Hanxia, Le Roux Johannes J, Jiang Zhaoyang, Sun Feng, Peng Changlian, Li Weihua
Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Guangzhou Key laboratory of Subtropical Biodiversity and Biomonitoring, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.
Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
New Phytol. 2021 Mar;229(6):3440-3452. doi: 10.1111/nph.17125. Epub 2020 Dec 28.
Invasive plants often change a/biotic soil conditions to increase their competitiveness. We compared the microbially mediated soil nitrogen (N) cycle of invasive Mikania micrantha and two co-occurring native competitors, Persicaria chinensis and Paederia scandens. We assessed how differences in plant tissue N content, soil nutrients, N cycling rates, microbial biomass and activity, and diversity and abundance of N-cycling microbes associated with these species impact their competitiveness. Mikania micrantha outcompeted both native species by transferring more N to plant tissue (37.9-55.8% more than natives). We found total soil N to be at lowest, and available N highest, in M. micrantha rhizospheres, suggesting higher N cycling rates compared with both natives. Higher microbial biomass and enzyme activities in M. micrantha rhizospheres confirmed this, being positively correlated with soil N mineralization rates and available N. Mikania micrantha rhizospheres harbored highly diverse N-cycling microbes, including N-fixing, ammonia-oxidizing and denitrifying bacteria and ammonia-oxidizing archaea (AOA). Structural equation models indicated that M. micrantha obtained available N via AOA-mediated nitrification mainly. Field data mirrored our experimental findings. Nitrogen availability is elevated under M. micrantha invasion through enrichment of microbes that participate in N cycling, in turn increasing available N for plant growth, facilitating high interspecific competition.
入侵植物常常改变生物和非生物的土壤条件以增强其竞争力。我们比较了入侵植物薇甘菊以及两种与其共生的本地竞争植物——中华蓼和鸡矢藤——的微生物介导的土壤氮循环。我们评估了这些植物的组织氮含量、土壤养分、氮循环速率、微生物生物量和活性，以及与这些物种相关的氮循环微生物的多样性和丰度差异如何影响它们的竞争力。薇甘菊通过向植物组织转移更多的氮（比本地植物多37.9% - 55.8%）而胜过这两种本地物种。我们发现薇甘菊根际土壤中的全氮含量最低，有效氮含量最高，这表明与两种本地植物相比，其氮循环速率更高。薇甘菊根际更高的微生物生物量和酶活性证实了这一点，它们与土壤氮矿化速率和有效氮呈正相关。薇甘菊根际含有高度多样的氮循环微生物，包括固氮菌、氨氧化细菌、反硝化细菌和氨氧化古菌（AOA）。结构方程模型表明，薇甘菊主要通过AOA介导的硝化作用获得有效氮。田间数据反映了我们的实验结果。通过富集参与氮循环的微生物，薇甘菊入侵下的氮有效性提高，进而增加了植物生长可用的氮，促进了种间竞争。
