Seasonal Changes in the Soil Microbial Community Structure in Urban Forests

Abstract

Urban forests play a crucial role in the overall health and stability of urban ecosystems. Soil microorganisms are vital to the functioning of urban forest ecosystems as they facilitate material cycling and contribute to environmental stability. This study utilized high-throughput sequencing technology to examine the structural characteristics of bacterial and fungal communities in the bulk soil of six different forest stands: Phyllostachys pubescens (ZL), Metasequoia glyptostroboides (SSL), Cornus officinalis (SZY), mixed broad-leaved shrub forest (ZKG), mixed pine and cypress forest (SBL), and mixed broad-leaved tree forest (ZKQ). Soil samples were collected from each forest stand, including the corners, center, and edges of each plot, and a combined sample was created from the first five samples. The results revealed that among the bacterial communities, ZKG exhibited the highest alpha diversity in spring, while ZL demonstrated the highest alpha diversity in both summer and autumn. Proteobacteria was the most abundant bacterial phylum in all six forest stand soils. The dominant fungal phylum across the six forest stands was identified as Ascomycota. Notably, the microbial community diversity of SBL bulk soil exhibited significant seasonal changes. Although ZL exhibited lower bacterial community diversity in spring, its fungal community diversity was the highest. The bulk soil microbial diversity of ZL and SSL surpassed that of the other forest stands, suggesting their importance in maintaining the stability of the urban forest ecosystem in the Zhuyu Bay Scenic Area. Furthermore, the diversity of the bulk soil microbial communities was higher in all six stands during spring compared to summer and autumn. Overall, this study provides valuable insights into the seasonal variations of bulk soil microbial communities in urban forests and identifies dominant tree species, offering guidance for tree species' selection and preservation in urban forest management.

Keywords: community diversity; seasonal changes; soil microbial; tree species; urban forest.

Figure 1

The variations in α diversity in the bulk soil of various city forest plots across three seasons. Pielou’s evenness (a,d), richness (b,e), Shannon index (c,f), bacterial (a–c) and fungal communities (d–f), The lower letters in the figure indicate the degree of difference between them.

Figure 2

Analysis of β diversity of bulk soil microbial communities in different stands in three seasons. (a) Principal coordinate analysis (PCoA) of bacterial communities; (b) PCoA of fungal communities.

Figure 3

The relative abundance of the top 10 bacterial and fungal phyla in bulk soil in urban forest stands in the three seasons (see also Supplementary file). Relative abundance of bacterial (a–c) and fungal communities (d–f) in spring (a,d), summer (b,e), and autumn (c,f).

Figure 4

Ternary map of bulk soil bacterial community OTUs during different seasons. The size of each point indicates the relative abundance of OTUs. (a) SBL, (b) SSL, (c) SZY, (d) ZKG, (e) ZKQ, and (f) ZL.

Figure 5

Ternary map of bulk soil fungal community OTUs in different seasons. The size of each point indicates the relative abundance of OTUs. (a) SBL, (b) SSL, (c) SZY, (d) ZKG, (e) ZKQ, and (f) ZL.

Figure 6

Species classification tree analysis (a,c) and dichotomous network analysis (b,d).