Strong partitioning of soil bacterial community composition and co-occurrence networks along a small-scale elevational gradient on Zijin Mountain

The elevational distributions of bacterial communities in natural mountain forests, especially along large elevational gradients, have been studied for many years. However, the distributional patterns that underlie variations in soil bacterial communities along small-scale elevational gradients in urban ecosystems are not yet well understood. Using Illumina MiSeq DNA sequencing, we surveyed soil bacterial communities at three elevations on Zijin Mountain in Nanjing City: the hilltop (300 m a.s.l.), the hillside (150 m a.s.l.), and the foot of the hill (0 m a.s.l.). The results showed that edaphic properties differed significantly with elevation. Bacterial community composition, rather than alpha diversity, strongly differed among the three elevations (Adonis: R-2 = 0.12, P<0.01). Adonis and DistLM analyses demonstrated that bacterial community composition was highly correlated with soil pH, elevation, total nitrogen (TN), and dissolved organic carbon (DOC). The degree scores, betweenness centralities, and composition of keystone species were distinct among the elevations. These results demonstrate strong elevational partitioning in the distributions of soil bacterial communities along the gradient on Zijin Mountain. Soil pH and elevation together drove the small-scale elevational distribution of soil bacterial communities. This study broadens our understanding of distribution patterns and biotic co-occurrence associations of soil bacterial communities from large elevational gradients to short elevational gradients. (C) Higher Education Press 2021

Automated summary

The study investigated the distribution patterns of soil bacterial communities along small-scale elevational gradients in an urban ecosystem. The results showed significant differences in edaphic properties and bacterial community composition among different elevations, which were strongly correlated with soil pH, elevation, total nitrogen, and dissolved organic carbon. This demonstrates strong elevational partitioning in the distributions of soil bacterial communities and the driving force of soil pH and elevation in the small-scale elevational distribution of these communities.