Responses of soil ammonia-oxidizing gene abundances and potential ammonia-oxidizing rate to Solidago canadensis invasion and soil types

Objectives Soil type and plant invasion are two important factors in shaping soil microbial community structure and function. Based on this, we studied the variation in gene abundances of soil ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) and the potential ammonia-oxidizing rate (PAOR), as well as the related mechanisms caused by Solidago canadensis invasion.

Methods Both Yunnan and Zhejiang Province have been heavily invaded by S. canadensis since 2010. The soil sampling areas were chosen nearby Dianchi of Yunnan Province and along the coastline of Eastern Zhejiang Province, covered 100–150 m² each area. In Yunnan, the three plots located in Haidong wetland park, Laoyu river wetland park and Anle village, where was alluvial soil. In Zhejiang, the three plots were in Hangzhou bay wetland park, Shangpan town of Linhai and Fengjiang village of Luqiao, where was yellow mud soil. In each plot, selecting three points of 0.5 m × 0.5 m with invasion of S. canadensis (Mono) and three points without (Nat). Plant and soil samples were collected and analyzed.

Results Under S. canadensis invasion, the AOA abundance and PAOR decreased in the alluvial soil but increased in the yellow mud soil, while the AOB abundances increased in both soil types. Under the native vegetation, both the AOA abundance and PARO in the alluvial soil were greater than those in yellow mud soil, while under S. canadensis vegetation, they were opposite. The AOB abundance in two soil types did not significantly changed no matter invaded by S. canadensis or not. In S. canadensis invaded point, the mediating factors for AOA abundance and PAOR were the above- and under-ground plant biomasses, soil organic matter content and pH, and that for AOB abundance in the alluvial soil was only underground plant biomass, and in yellow mud soil were underground plant biomass, total P content and pH.

Conclusions S. canadensis has much higher above- and under-ground biomass than native plants, the evasion of S. canadensis provides much more organic carbon source and leads to increased soil pH, therefore, S. canadensis invasion obviously influences AOA, AOB abundance and the potential ammonia oxidation rate in two soil types. Soil type only affects AOA abundance, but had no significant effect on AOB abundance and the potential ammonia oxidation rate.