With industrialization and widespread chemical use, soil organic pollutants have become a major environmental issue. Forest ecosystems, among the most important on Earth, have unique potential for controlling and remediating soil pollution. This article explores the mechanisms of microbial community degradation of organic pollutants, their adaptability across forest ecological conditions, and the effects of environmental factors on degradation efficiency. For example, acidic pH (pH < 5.5) favors PAH degradation, near-neutral pH (6.0–7.5) enhances pharmaceutical and PPCP degradation, and alkaline conditions (pH > 7.5) facilitate petroleum hydrocarbon, VOC, and PPCP breakdown. Optimal microbial degradation occurs with humidity levels between 60% and 80%, and SOM content of 2–5%. This review analyzes advancements in microbial degradation technologies for forest ecosystem soil pollution treatment, including genetic engineering, composting, bioaugmentation, and bio-stimulation techniques, and their integration with phytoremediation. The review also addresses the challenges of real-world implementation, such as maintaining microbial diversity, managing pollutant complexity, adapting to environmental changes, and highlighting future research opportunities. The next decade will focus on synthetic biology, omics technologies, microbial-electrochemical systems, community dynamics, eco-engineering, and plant-microbe synergy to develop efficient, sustainable bioremediation strategies.

Fertilization is widely acknowledged as being an essential practice to improve forest productivity in forest ecosystems. However, too little consideration has been given to the taxonomic and functional compositions of rhizosphere soil microbes and their interactions with root exudates under different fertilizer regimes in forest plantations. Here, we investigated the effects of four typical fertilizer regimes (CK, no fertilizer; CF, compound fertilizer; OF, organic fertilizer; CMF, compound microbial fertilizer) on soil microbial communities and their potential functional groups in Phoebe bournei young plantations, as well as their associations with soil physicochemical properties and root exudates. These results showed that fertilizer regimes strikingly affected the rhizosphere soil microbial community compositions and alpha diversity indices. The pathotroph was the dominant fungal guild. With the applications of three fertilizations, the relative abundances of the plant pathogen and arbuscular mycorrhiza increased. The alpha diversity of soil bacteria was highest under the OF regime, and soil fungal diversity was more powerfully affected by the amendment of CMF. Additionally, while the fungal community was simultaneously influenced by soil physiochemical factors and root exudates, the bacterial community in the rhizosphere was mostly impacted by root exudates. More importantly, the application of OF and CF induced dramatic growths of Fusarium, while CMF treatment including Bacillus suppressed the development of Fusarium via adjusting bacterial species. Overall, our findings exhibit the divergent responses of rhizosphere bacteria and fungi to fertilizer regimes in P. bournei young plantations. The application of organic fertilizer provides benefits for rhizosphere bacteria, and microbial fertilizer can help alleviate inhibition through changing pathogens.

The effects of foliar spraying with spermidine (Spd) on the subcellular distribution and chemical speciation of Cd in Typha latifolia L. in hydroponic system were investigated. Increased Cd concentration in the medium caused an increase of Cd concentration in all tissues and all subcellular fractions, with the highest Cd level occurring in roots, followed by rhizomes and leaves and the greatest accumulation was in cell walls, soluble fraction and organelle containing fractions ranked next, respectively. The greatest amount of Cd was found in the extraction of 1 mol·L⁻¹ NaCl, followed by 2% HAC, deionized water, 80% ethanol, residues and the least in 0.6 mol·L⁻¹ HCl. The subcellular distribution and different chemical forms of Cd both decreased after Spd application and were more inhibited by 0.25 than 0.50 mmol·L⁻¹ Spd, especially in roots at 0.10 mmol·L⁻¹ Cd treatment. It could be suggested that the retention of Cd in roots, cell walls binding with metal, metal ion compartmentation in vacuoles and Cd forms existing in undissolved and integrated with pectates and protein play an important role in Cd detoxification and Spd could enhance the tolerance of cattail to Cd stress.

Albizia odoratissima is a deciduous tree species belonging to the family Leguminosae. It is widely distributed in the southern subtropical and tropical areas of China and has important ecological and economic value. The growth and metabolic processes of A. odoratissima are affected by drought stress, but the molecular mechanisms remain unknown. Therefore, this study investigated the physicochemical properties, gene expression, and metabolites of A. odoratissima seedlings under drought stress. The results show that, in leaves of A. odoratissima seedlings, drought stress reduced the moisture content, chlorophyll content, photosynthetic efficiency, superoxide dismutase (SOD) activity, and gibberellin (GA) and indoleacetic acid (IAA) contents while increasing the catalase (CAT) and peroxidase (POD) activities and malondialdehyde (MDA), proline, soluble sugar, and soluble protein contents. Within the CK5 (Day 5 of control group) vs. T5 (Day 5 of drought treatment), CK10 vs. T10, CK15 vs. T15, and CK20 vs. T20 groups (CK: control group; T: drought treatment), a total of 676 differentially expressed genes (DEGs) were upregulated and 518 DEGs were downregulated, and a total of 228 and 143 differential accumulation metabolites (DAMs) were identified in the CK10 vs. T10 and CK20 vs. T20 groups. These were mainly involved in the amino acid and alkaloid metabolism pathways in the leaves of the A. odoratissima seedlings. In the amino acid and alkaloid biosynthesis pathways, the relative expression levels of the AoproA (Aod04G002740, ORTHODONTIC APPLIANCE), AoOAT (Aod07G015970, ORNITHINE-OXO-ACID TRANSAMINASE), and AoAOC3 (Aod12G005010/08G003360/05G023920/08G003000/08G003010, AMINE OXIDASE COPPER CONTAINING 3) genes increased, which concurrently promoted the accumulation of arginine, proline, piperine, cadaverine, and lysine. Furthermore, some key transcription factors in the response to drought were identified in the leaves using the weighted gene co-expression network analyses (WGCNA) method. These findings reveal that A. odoratissima seedlings respond to drought stress by improving the capacities of the antioxidant system and secondary metabolism.

The utilization of remediating plants is an important factor that restricts phytoremediation. Ramie has good adsorption capacity for various heavy metals and is widely used in plant remediation. To achieve the multi-purpose development of heavy metal-contaminated ramie, research has been conducted on the preparation of biochar for using it as a raw material, and the feasibility of returning the prepared biochar to the soil has been explored. The results indicate that 300 ℃ is the appropriate pyrolysis temperature for preparing ramie biochar. Under these conditions, the biochar yield is 42.90 ± 2.29%, significantly higher than other pyrolysis temperatures, and the arsenic concentration is also lower. Removing arsenic from ramie biochar is crucial for biochar to return to the soil, and 85.62 ± 1.36% of arsenic can be removed through three rounds of 300 mM sodium hydroxide extraction. Adding modified biochar to heavy metalcontaminated soil can increase soil pH and organic matter content but does not significantly increase soil arsenic content. However, adding modified biochar did not significantly alter soil microbial community structure. A feasible plan for preparing reusable biochar using contaminated ramie was proposed in this study. The research results can directly serve the remediation of soil arsenic pollution using ramie and have reference significance for other plants to carry out heavy metal remediation.

The reuse of heavy-metal hyperaccumulator waste has emerged as a critical constraint in the implementation of phytoremediation to control heavy-metal pollution. Ramie (Boehmeria nivea) is a wellestablished arsenic (As) hyperaccumulator that has been widely used in the remediation of As-contaminated sites in recent years. To facilitate multipurpose development and the recycling of ramie straw contaminated with heavy metals, a study investigated the preparation of hydrochar (HC) at different temperatures and assessed the feasibility of reintroducing the HC into the soil. The results indicated higher yields, increased nutrient contents, and reduced As percentage levels at a hydrothermal carbonization temperature of 240℃. Treatment with a 300 mmol/L sodium hydroxide solution resulted in the removal of As from HC, ranging from 77.06% to 87.60%, effectively facilitating the reuse of HC. The application of alkali-modification HC in As-contaminated soil not only enhances soil properties but also augments the potential population of dominant microorganisms that promote soil arsenic mobilization, thereby improving arsenic mobilization capacity in mining soil. This study offers a viable strategy for enhancing the phytoremediation efficiency of As-contaminated soil and establishing a recycling system for As hyperaccumulator resources in the future.