Monoculture plantation systems face increasing challenges in sustaining ecosystem multifunctionality (EMF) under intensive management and climate change, with long-term functional trajectories remaining poorly understood. Although biodiversity–EMF relationships are well-documented in natural forests, the drivers of multifunctionality in managed plantations, particularly age-dependent dynamics, require further investigation. This study examines how stand development influences EMF in Castanopsis hystrix L. plantations, a dominant subtropical timber species in China, by assessing six ecosystem functions (carbon stocks, wood production, nutrient cycling, decomposition, symbiosis, and water regulation) of six forest ages (6, 10, 15, 25, 30, and 34 years). The results demonstrate substantial age-dependent functional enhancement, with carbon stocks and wood production increasing by 467% and 2016% in mature stand (34 year) relative to younger stand (6 year). Nutrient cycling and water regulation showed intermediate gains (6% and 23%). Structural equation modeling identified plant diversity and microbial community composition as direct primary drivers. Tree biomass profiles emerged as the strongest biological predictors of EMF (p < 0.01), exceeding abiotic factors. These findings highlight that C. hystrix plantations can achieve high multifunctionality through stand maturation facilitated by synergistic interactions between plants and microbes. Conservation of understory vegetation and soil biodiversity represents a critical strategy for sustaining EMF, providing a science-based framework for climate-resilient plantation management in subtropical regions.

The ecological restoration of tropical islands, such as the Xisha Islands, is critical for sustainable development but is hindered by extreme environmental conditions and nutrient-poor coral sand soils. This study assessed the adaptive strategies of two introduced landscape species, Acacia auriculiformis and Nerium oleander, by comparing their leaf physiological and biochemical traits across three treatments: native coral sand (SS2), coral sand amended with garden soil (SS1), and a garden soil control (GZ). Results revealed differentiated physiological adaptation strategies: N. oleander exhibited a ‘conservative tolerance’ strategy, characterized by maintaining higher levels of soluble proteins and the non-enzymatic antioxidant GSH, whereas A. auriculiformis employed an ‘active defense’ strategy, significantly upregulating its enzymatic antioxidant system (SOD activity increased by up to 58.80% in coral sand compared to the control). Soil amendment was crucial for improving plant performance by fundamentally altering the soil’s physicochemical properties and nutrient status. Specifically, amending coral sand with garden soil (SS1 vs. SS2) resulted in a threefold increase in both soil organic carbon (from 3.81 to 11.63 g kg⁻¹) and water content (from 0.04% to 0.12%), while also increasing available phosphorus by over 50% and reducing the extreme soil alkalinity. This amelioration of the soil environment directly enhanced plant antioxidant capacity and overall growth performance. These findings provide a scientific basis for plant introduction on tropical islands, demonstrating that success depends on matching species-specific adaptive strategies with appropriate soil improvement techniques.

Sustainable soil management requires striking a balance between productivity and soil health. While agroforestry practices are known to improve soil health and ecosystem functions, the contribution of microbial diversity to maintaining multifunctional soil processes in pecan (Carya illinoinensis) cultivation has yet to be fully elucidated. This study examined microbial diversity, soil functions, and multifunctionality across different pecan intercropping setups. We compared a monoculture pecan plantation with three agroforestry models: pecan–Paeonia suffruticosa–Hemerocallis citrina (CPH), pecan–P. suffruticosa (CPS), and pecan–P. lactiflora (CPL). We employed high-throughput sequencing (16S and ITS) to determine the soil bacterial and fungal communities and analyzed the species diversity, extracellular enzyme activities, and physicochemical properties. Soil multifunctionality (SMF) was evaluated using 20 indicators for nutrient supply, storage, cycling, and environmental regulation. Agroforestry increased soil fungal diversity and improved multifunctionality when compared to monoculture. The CPS and CPH models were the most beneficial, increasing multifunctionality by 0.74 and 0.55 units, respectively. Structural equation modeling revealed two key pathways: bacterial diversity significantly enhanced nutrient cycling and environmental regulation, whereas fungal diversity primarily promoted nutrient cycling. These pathways together delivered clear gains in multifunctionality. Random forest analysis identified key predictors (total nitrogen, total carbon, available potassium, β-1,4-N-acetylglucosaminidase, and alkaline phosphatase), highlighting the joint importance of nutrients and microbial enzymes. Our results demonstrate that selecting species in pecan agroforestry alters microbial communities and activates key functions that support soil health and long-term resilience. Hence, pecan agroforestry maintains SMF through microbial processes, with CPS showing the strongest effect. These results can inform species selection and encourage broader testing for resilient, biodiversity-based farming practices.

Strigolactones (SLs) have emerged as important regulators of plant adaptation to abiotic stress, functioning not as isolated hormones but as integrative signaling molecules. Beyond stress responses, SLs regulate key biological processes, including shoot branching, root architecture, leaf senescence, nutrient acquisition, rhizosphere communication, flowering-related development, and growth–developmental plasticity. This review synthesizes current knowledge on how SLs modulate plant responses to drought, salinity, heavy metal toxicity, high temperature, and low temperature through crosstalk with abscisic acid, auxin, cytokinin, ethylene, and gibberellin. We examine SL structural diversity, biosynthesis, transport, and signaling together with their roles in growth–stress coordination, hormonal networking, and stress-specific mitigation, while distinguishing endogenous SL functions from responses inferred from exogenous analogs such as GR24. Across stresses, SL-mediated resilience converges on adaptive modules, including water regulation, root–shoot architectural remodeling, redox protection, ion and osmotic homeostasis, photosynthetic maintenance, and rhizosphere-assisted resource acquisition. The mechanistic basis involves transcriptional reprogramming, ROS/RNS-linked redox regulation, metabolic protection, and root–microbe interactions. Translational prospects include SL analogs, genetic manipulation, and breeding for adaptive plasticity, nutrient efficiency, and stress tolerance. However, species specificity, dosage dependence, limited field validation, unclear structure–function relationships, and parasitic-weed stimulation remain major constraints.

Abiotic stresses increasingly threaten crop productivity, whereas reliance on chemical and resource-intensive interventions can compromise environmental sustainability. Existing literature identifies Trichoderma spp. as multifunctional biocontrol agents, biofertilizers, and microbial biostimulants capable of influencing plant growth, stress signaling, and rhizosphere processes; however, evidence remains fragmented across strains, crops, formulations, and stress conditions. This review aimed to integrate current knowledge on Trichoderma-mediated resilience to salinity, drought, heavy metals, temperature extremes, and emerging pollutants, while distinguishing experimentally validated mechanisms from statistical associations and conceptual inference. It evaluates constraints governing reproducibility from controlled studies to field deployment. The synthesis shows that selected crop–strain systems improve root architecture, photosynthesis, antioxidant regulation, osmotic adjustment, nutrient acquisition, ion homeostasis, hormonal balance, and stress-responsive gene expression. Benefits arise through coordinated delivery, root colonization, metabolite and protein signaling, physiological reprogramming, and rhizosphere modulation. Nevertheless, microbiome co-occurrence patterns do not establish causal network repair, evidence for broad heat and cold protection remains limited, and biochar co-application should not be interpreted as a carrier formulation without direct validation. Future progress requires strain- and crop-specific screening, mechanistic gene and protein studies, standardized formulations, combined-stress experiments, multi-location field trials, biosafety evaluation, and farmer-level economic assessment to develop reliable precision microbial technologies.

Forest enclosure is widely used for degraded forest restoration; however, microbial functional recovery across enclosure durations in subtropical deciduous secondary broadleaved forests remains poorly understood. This study evaluated microbial carbon metabolic recovery and associated environmental factors across a chronosequence of forests enclosed for 0–1, 5–6, 11–12, 20–24, and 28–34 years, with an old-growth forest as the reference. Forest enclosure significantly enhanced microbial carbon metabolic capacity and functional diversity. Average Well Color Development (AWCD) and Shannon, Simpson, and McIntosh indices increased with enclosure duration, with the lowest values in 0–1 year stands and the highest values in old-growth forests. Enclosure duration significantly altered carbon source utilization patterns, particularly amino acids and carboxylic acids, with carboxylic acids becoming the dominant utilized carbon source category after 5–6 years of enclosure. Furthermore, Bray–Curtis distance analysis revealed progressive convergence of microbial carbon-use profiles toward the old-growth reference state with increasing enclosure duration (Spearman’s ρ = −0.61, p = 0.0155). Soil carbon, nitrogen, moisture, bulk density, pH, and microbial diversity were significantly associated with these functional changes. These findings highlight microbial carbon-use profiles as effective indicators of soil functional recovery and provide insights for incorporating microbial traits into future forest restoration and management strategies.