• In contrast to the QT region, where S. chamaejasme soils had higher N but not P, the IM region exhibited no such N increase, and its control soils were low in P. • Bacterial responses to S. chamaejasme establishment differed regionally, with QT region showing increased relative abundances of some diazotrophs that correlated with soil N, whereas no similar trends were detected in IM region. • The ability of S. chamaejasme to interact differently with soil microbial communities and nutrients depending on local soil conditions is a key mechanism that may contribute to its successful expansion across diverse grassland ecosystems in China. Stellera chamaejasme is a pernicious plant of grasslands in China. Its expansion has been linked to changes in the soil microbial community structure and to nitrogen accumulation. Increased nitrogen availability may enhance competitiveness of the weed and disrupt plant community structure. We sought to establish whether presence of this species evokes the same changes to soil properties and microbiome community structure in regions with divergent native soil properties. For this, we compared soil samples collected from under native vegetation (controls) with those taken from beneath S. chamaejasme plants in grasslands of eastern Qinghai–Tibet Plateau (QT) and the middle Inner Mongolia Plateau (IM). In QT, soil beneath S. chamaejasme contained higher nitrogen levels than controls, but not phosphorus. In contrast, S. chamaejasme and control soil samples from IM did not differ in nitrogen content, but S. chamaejasme soil samples had raised soil P. Soil bacterial community responses to S. chamaejasme also differed between regions. S. chamaejasme soils from QT had increased relative abundances of some diazotrophs ( Bradyrhizobium, Mesorhizobium, Phyllobacterium ) that positively correlated with soil nitrogen but no similar tends were detected in IM soils. Redundancy analysis revealed significant associations between soil ammonium and bacterial genera implicated in soil N-cycles. In QT, modelling suggested that S. chamaejasme increased N-cycling soil bacteria linked to increased available nitrogen. However, in IM soil N-cycling soil bacteria and soil nitrogen levels were unaffected by S. chamaejasme and its presence did not link to N-based soil changes. We conclude that S. chamaejasme evokes different changes to the native soils of these two regions. We postulate that S. chamaejasme may exhibit plasticity in response to soil conditions it encounters and that this may be one reason for its soil impact being context dependent. This divergent interaction between S. chamaejasme and host soils may facilitate further expansion of its current range.
He et al. (Thu,) studied this question.