Soil nitrogen dynamics and competition during plant invasion

insights from Mikania micrantha invasions in China

Hanxia Yu, Jaco Le Roux, Zhaoyang Jiang, Feng Sun, Changlian Peng, Weihua Li

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish
Number of pages13
JournalNew Phytologist
Early online date1 Dec 2020
DOIs
Publication statusE-pub ahead of print - 1 Dec 2020

Keywords

  • Mikania micrantha
  • biological invasions
  • functional microbial diversity
  • nitrification
  • nitrogen cycle
  • nitrogen fixation

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