Global CO₂ concentrations are gradually increasing, and forests, as the main terrestrial carbon pool, are attracting growing attention in mitigating climate change. However, the impacts of forest types, species diversity, structural diversity, and environmental factors on the carbon sequestration mechanisms of subtropical forests remain unclear. This study established 45 forest plots (20 m × 20 m) in Lishui City, aiming to investigate the relationships between forest diversity, environmental factors, and carbon storage of subtropical forests among different forest types. Results showed that coniferous forests had the lowest species diversity (0.86), which exhibited extremely significant differences from broad-leaved forests (1.47, p < 0.01) and coniferous broad-leaved mixed forests (1.58, p < 0.01). The carbon storage of broad-leaved forests was 97.50 t·ha⁻¹, which was higher than that of coniferous broad-leaved mixed forests (77.08 t·ha⁻¹) and coniferous forests (75.57 t·ha⁻¹). The carbon storage of coniferous forests was significantly positively affected by species diversity (p < 0.05). Tree height was the most significant structural diversity factor affecting forest carbon storage (p < 0.05). The results of the structural equation model (SEM) showed that the proportion of broad-leaved trees in forests and structural diversity had a significant positive effect on carbon storage (p < 0.01). Species diversity had a non-linear relationship with carbon storage. The ecological niche complementarity effect and selection effect interacted with changes in species diversity. When the species diversity was lower than 1.12 (Shannon–Wiener index), the ecological niche complementarity effect dominated and promoted carbon sequestration; when it was above this threshold, the selection effect dominated and weakened carbon sequestration. This study recommends prioritizing the planting of broad-leaved tree species during afforestation and paying attention to the current status of forest diversity.

Fertilization is widely used in managed Moso bamboo (Phyllostachys edulis (Carrière) J.Houz.) forests in subtropical China, but its short-term effects on soil properties and microbiomes remain uncertain. In this study, we conducted a field experiment with four treatments: no fertilization (NF), compound fertilizer (CF), sheep manure organic fertilizer plus compound fertilizer (SOCF), and a biochar-based sheep manure organic fertilizer combined with compound fertilizer (BSOCF). Surface soils samples were collected approximately one year after the initial application, and soil properties were measured together with bacterial and fungal communities using high-throughput sequencing. Results showed that fertilization mainly affected soil chemical properties rather than overall microbial community structure. Compared with CF, BSOCF significantly increased soil pH (4.56 ± 0.10 vs. 4.30 ± 0.05) and resulted in the highest available phosphorus (AP, 6.38 ± 1.10 mg kg⁻¹) and available potassium (AK, 128.16 ± 17.56 mg kg⁻¹) contents. Microbial responses were comparatively limited. Bacterial richness remained stable, fungal alpha diversity showed only a weak increasing trend, and both beta diversity and phylum-level composition changed little among treatments. Variation in treatment-enriched taxa was associated mainly with soil pH and nutrient availability. Overall, the results indicate that biochar-based sheep manure organic fertilizer can improv soil fertility and partially alleviated soil acidity, while causing only limited short-term shifts in the overall microbial community structure. These findings suggest that BSOCF may be a suitable fertilization strategy for enhancing nutrient availability in Moso bamboo forests with relatively low short-term disturbance to soil microbial assemblages.

Bamboo compost is a renewable organic material that can replace peat and enhance plant resistance to insect pests. However, its combined effects on tomato (Solanum lycopersicumL.) growth, defense responses, and underlying molecular mechanisms remain unclear. In this study, bamboo compost was incorporated into growing substrates at varying proportions (5–30%) to assess its impact on tomato seedling growth, physiological and biochemical traits, and the survival of the South American tomato leafminer, Tuta absoluta. Metabolomic and transcriptomic analyses were further integrated to characterize molecular changes associated with enhanced resistance. The results showed that 10% bamboo compost increased plant height and stem diameter by 25.91% and 10.19%, respectively, while higher proportions inhibited seedling growth. All bamboo compost treatments significantly reduced Tuta absoluta. larval survival, with the lowest day-10 survival (16%) observed under BC−20%. Multi-omics analyses identified 1553 and 2591 DEGs and 292 and 591 DAMs in the BC−10% vs. CK and BC−20% vs. CK comparisons, respectively; 290 differentially expressed transcription factor-encoding genes were identified across both comparisons. BC−20% showed broader defense-related transcriptional and metabolic reprogramming, including MAPK and phytohormone signaling, phenylpropanoid and flavonoid biosynthesis, and cutin and wax formation, but with reduced growth. Overall, BC−10% represents a suitable practical addition rate for promoting tomato seedling growth in peat-reduced cultivation substrates.