Microbial-Mediated Soil Nutrient Enhancement in Moso Bamboo- Liquidambar formosana vs. Phoebe chekiangensis Mixed Plantings

Abstract

This study investigated how Moso bamboo (Phyllostachys edulis)-broadleaf mixed forests influence soil properties and microbial communities to support ecological function and sustainable bamboo forest management. Three forest types were examined: pure Moso bamboo stands (MB) and mixed stands with Liquidambar formosana (LB) or Phoebe chekiangensis (PB). Soil chemical properties, microbial diversity, and community composition were assessed using high-throughput sequencing, and functional taxa were correlated with soil nutrients. The results showed that mixed forests significantly influenced soil chemical properties. PB showed the lowest pH and highest total nitrogen (TN), while MB exhibited the highest soil organic matter (SOM) and total potassium (TK). LB maintained moderate TN, high SOM and TK, and stable pH, indicating a balanced nutrient profile. Although α-diversity did not differ significantly, β-diversity analysis revealed distinct microbial community structure (p < 0.01). LB was enriched with carbon-decomposing taxa (Terriglobales and Sphingomonas), PB with acid-tolerant, nitrogen-cycling groups (Candidatus Binatus), and MB with nitrogen-fixing taxa (Nitrobacteraceae and Bradyrhizobium). Co-occurrence network and functional pathway analyses indicated group-specific microbial associations and greater metabolic diversity in LB and PB. In conclusion, mixed Moso bamboo with broadleaf species significantly modified soil chemical properties and microbial community structure, with the Moso bamboo-L. formosana combination showing potential for improving soil nutrient status and microbial function.

Keywords: Liquidambar formosana; Moso bamboo; broadleaf transformation; soil microbial structure and function; soil nutrients.

Figure 1

Variation in Soil Chemical Properties Across Different Forest Types. Note: Different lowercase letters indicate significant differences among forest types (p < 0.05). TN: total nitrogen, TP: total phosphorus, TK: total potassium, SOM: soil organic matter. LB represents the mixed forest of Moso bamboo and Liquidambar formosana, PB represents the mixed forest of Moso bamboo and Phoebe chekiangensis, and MB represents the pure Moso bamboo forest.

Figure 2

Functional Characteristics and Diversity Distribution of Soil Microbial Communities Across Different Forest Types. Note: (A) Length distribution of assembled coding sequences (CDS). (B) Distribution of non-redundant gene counts (Venn diagram). (C) Species relationship diagram identifying microbial genera at the genus level. (D) α-diversity of microbial communities (Shannon, Simpson, and Invsimpson indices). In the box plot, the horizontal line represents the mean, and the upper and lower boxes represent the upper and lower quartiles. (E–G) Principal component analysis (PCA), principal coordinate analysis (PCoA), and non-metric multidimensional scaling analysis (NMDS) plots. Different colors represent soil samples from different forest types. In the PCA and PCoA plots, the distance between sample points reflects their similarity in microbial community composition and relative abundance. Points that are closer together indicate similar community structures, whereas points that are farther apart suggest greater differences. In the NMDS plot, stress < 0.05 indicates an excellent fit, while 0.05 ≤ stress < 0.1 indicates a very good fit. (H) Venn diagram of the number of identified species at the taxonomic level among different groups. LB represents the mixed forest of Moso bamboo and Liquidambar formosana, PB represents the mixed forest of Moso bamboo and Phoebe chekiangensis, and MB represents the pure Moso bamboo forest.

Figure 3

Soil Microbial Community Structure and Differential Species Identification Across Different Forest Types. Note: (A,B) Bar plots showing microbial composition at the phylum (A) and genus (B) levels, with different colors representing various taxonomic groups. (C) Non-parametric test (ANOSIM) based on the distance matrix. (D,E) Linear discriminant analysis effect size (LEfSe) with a selection criterion of LDA score > 3. Taxonomic labels follow the format: p = phylum, c = class, o = order, f = family, g = genus. (F,G) Kruskal–Wallis test for differential abundance of the top 40 most abundant microbes at the genus and species levels. LB represents the mixed forest of Moso bamboo and Liquidambar formosana, PB represents the mixed forest of Moso bamboo and Phoebe chekiangensis, and MB represents the pure Moso bamboo forest.

Figure 4

Analysis of Differential Microbial Functions and Their Correlation with Soil Nutrients Across Different Forest Types. Note: (A) Co-occurrence network of the top 100 microbial species. (B) Stacked bar chart showing the distribution of the top 10 enzyme commission (EC) functions. (C) Stacked bar chart showing the distribution of the top 10 KEGG Orthology (KO) functions. (D) Stacked bar chart showing the distribution of the top 10 KEGG pathway functions. (E) Correlation analysis between differential microbial species and soil nutrient contents. * indicates p < 0.05 (significant), ** indicates p < 0.01 (highly significant), and *** indicates p < 0.001 (extremely significant).