pH drives ammonia oxidizing bacteria rather than archaea thereby stimulate nitrification under Ageratina adenophora colonization

- Significant higher NO3−-N content was observed under overgrowing plant A. adenophora.
- AOB abundance increased in the presence of A. adenophora.
- pH was positively correlated with AOB but negatively correlated with AOA abundance.
- Increased AOB abundance possibly played important role in promoting nitrification.

Understanding mechanisms of successful colonization by exotic plant species in non-native habitat is critical to meet long-term restoration aims. Overgrowing plants can alter resources, especially soil inorganic nitrogen availability and get benefits from positive feedback. However, comprehensive knowledge on particular mechanisms underlying their successful colonization remains unclear. Here, field examinations and laboratory manipulations were combined to investigate significant impact of overgrowing Ageratina adenophora on soil NO3−-N availability and nitrification. Interestingly, we found significant enhancement in soil total N, NO3−-N, pH, potential nitrification rates, and ammonia oxidizing bacteria (AOB), while reduced abundance of ammonia oxidizing archaea (AOA) under the influence of A. adenophora. Notably, AOB abundance was positively correlated with both pH and soil potential nitrification rates. AOA abundance was negatively correlated with pH and had no significant correlation with soil nitrification potential. Both AOA and AOB communities significantly differed between populated and non-populated soils. pH was the strongest factor contributing to this community difference. We conclude that A. adenophora stimulates nitrification with the help of AOB rather than AOA under relatively higher soil pH condition.