Phosphorus (P) availability is often limited in subtropical acidic soils due to fixation by iron and aluminum oxides, constraining nutrient uptake and productivity in Camellia oleifera plantations. However, the mechanisms by which the effects of artificial nitrogen (N) application and natural N fixation via legume intercropping on soil P dynamics remain poorly understood. In this study, the independent effects of legume intercropping and N application on soil P fractions, soil biochemical properties and leaf nutrient content were investigated in C. oleifera plantations in subtropical China. Six treatments were applied: monoculture with weeding, monoculture without weeding, intercropping with Cassia tora or peanut, and monoculture with low or high N application (25 or 50 g urea per plant). Soil P fractions, soil organic carbon, total N, pH, ammonium (NH4+-N), nitrate (NO3--N), acid and alkaline phosphatase activities, and leaf C, N, and P contents were measured at the growth (July) and mature (September) stages. Results showed that both legume intercropping and low N application independently enhanced total and labile soil P, increased soil organic carbon, and improved leaf nutrient contents compared to the control. High N initially reduced labile P but partially recovered by maturity. Phosphatase activities declined at maturity but remained higher in intercropped and fertilized plots, indicating improved P cycling. Nitrate N concentrations increased from the growth stage to the mature stage. These results suggest that legume intercropping and N application, when applied independently, each promote soil P availability and plant nutrient uptake, highlighting practical strategies to enhance soil fertility and sustain C. oleifera production in subtropical acidic soils.

The rapid expansion of photovoltaic (PV) infrastructure is crucial for climate mitigation, yet its ecological consequences─particularly on soil ecosystems─remain poorly understood. Here, we investigate the effects of PV coverage on soil microbial communities and ecosystem multifunctionality (EMF) across three land-use types (arable land, forest land, and tailings). PV coverage was associated with significant changes in soil microbiomes, suppressing phototrophic taxa while promoting heterotrophic and parasitic lineages in tailings soils. Critically, PV was associated with a severe decline (relative change: -1.02) in EMF within tailings, while EMF was higher in arable land by 2.21-fold. Structural equation modeling suggested soil moisture as the likely primary factor associated with EMF degradation in tailings. Microbial network complexity emerged as a positive correlate of EMF in arable land. These results underscore the context-dependent ecological impacts of PV installations and highlight the potential to modulate these effects through adjustable engineering designs, informing sustainable land-use planning for solar energy development.

Soil microorganisms are key regulators of soil organic carbon (SOC) transformation and stabilization. Biochar (BC), as a carbon (C)-rich soil amendment, can improve soil quality, microbial habitats, and substrate availability, thereby potentially altering SOC dynamics. However, the microbial mechanisms through which BC influences SOC fractions in plantation soils remain poorly understood. In this study, a two-year pot experiment was conducted using soils from a Quercus glauca-Chinese fir mixed plantation to evaluate the effects of BC addition on soil properties, microbial community composition, C source utilization, and C cycling-related functional genes. Microbial C source utilization was assessed using Biolog EcoPlate, while microbial community structure and functional potential were characterized by amplicon sequencing and metagenomic sequencing, respectively. The results showed that BC addition significantly increased SOC and its fractions, especially particulate organic C (POC) and mineral-associated organic C (MAOC), while simultaneously changing C metabolic profiles, and these responses were different in the two sampling time points. One year after BC application (T1), BC promoted the relative abundance of several bacterial taxa potentially involved in soil C cycling, enhanced the utilization of labile C substrates, and increased the abundance of genes involved in C fixation and selected C degradation pathways. Two years after BC application (T2), microbial C-source utilization and overall substrate metabolic activity declined, accompanied by shifts in microbial community composition and an increased contribution of MAOC to total SOC. The results indicate that BC regulates SOC sequestration in subtropical plantation soils by changing microbial C metabolism and functional potential, thereby favoring the accumulation and stabilization of soil C.

Microbial residue carbon (MRC) is crucial for soil organic carbon (SOC) sequestration, yet its temporal dynamics during plantation development and successive rotation remain unclear. This study investigated SOC fractions, microbial living biomass, and microbial residues to estimate the contribution of MRC to SOC in 8-, 16-, 24-, and 34-year-old second-generation Chinese fir plantations, with a 106-year-old original plantation serving as the control. The results revealed that SOC content increased with stand age, exceeding the control level at the 34-year-old stand. Soil microbial living biomass and MRC content exhibited a decline-then-increase trend with stand age, remaining below the control. The contribution of MRC to SOC decreased with stand age and was significantly higher in the 8-year-old stand than in the control, averaging 30.7% of the SOC. Although SOC fractions and microbial parameters were higher in the topsoil, the contribution of MRC to SOC was greater in the subsoil. Notably, soil fungi accounted for 14.3% of the microbial living biomass, yet their residues accounted for 84.9% of the MRC. The positive association between mineral-associated organic carbon and fungal residues was markedly stronger than that for bacterial residues. Random forest and mixed-effect analyses indicated that MRC accumulation was primarily regulated by microbial living biomass and soil carbon and nitrogen, rather than by plant growth metrics. Path analysis further confirmed the strongest direct influence of soil microbial living biomass on MRC accumulation. Our findings elucidate the dynamics of MRC accumulation and its role in long-term SOC sequestration during plantation development in subtropical China.

Mangrove ecosystems are among the most productive and carbon-dense coastal forests globally, playing a critical role in plant diversity conservation and climate regulation. However, spatial variability in plant diversity, biomass allocation, and vegetation biomass carbon storage remains insufficiently quantified at regional scales, particularly in biogeographically complex regions such as Hainan Island, China. Here, we investigated four representative mangrove regions in Hainan Province: Dongzhai Port (DPMD), Qinglan Port (QPMD), Yalong Bay (YBMD), and Xinying Port (XPMD). Based on 73 field plots (0.5 ha each), we quantified species composition, community diversity, importance value index (IVI), organ-level biomass allocation (leaves, stems, and roots), and vegetation biomass carbon storage using species-specific allometric equations and published carbon concentration factors. A total of 12 mangrove species from 7 families were recorded, with Rhizophora stylosa Griff. consistently dominating across all sites (IVI range: 19.8-58.7%). Significant spatial heterogeneity was observed in all measured parameters. QPMD exhibited the highest total biomass (92.2 t ha-1) and plant vegetation biomass carbon storage (40.1 t C ha-1), whereas YBMD showed the lowest biomass (26.1 t ha-1) and XPMD exhibited the strongest species dominance (Simpson's D = 0.58). Stem biomass contributed the largest proportion (60-80%) across all sites, while root and leaf allocation varied significantly among regions, reflecting differences in community structure and stand characteristics. Vegetation biomass carbon storage patterns closely followed biomass distribution, demonstrating the dominant role of vegetation productivity in determining plant carbon accumulation. Our results reveal substantial spatial variation in mangrove diversity, biomass production, and vegetation biomass carbon storage. This study provides essential baseline information on mangrove vegetation biomass carbon stocks for region-specific conservation prioritization and climate mitigation strategies in tropical China.

Phosphorus (P) influences the soil nutrient cycle, microbial function and plant growth, but the mechanism of P additions promoting the growth of Phellodendron chinense Schneid is not documented. In this study, CK (0 g & sdot;m-2), P5 (5 g & sdot;m-2), P10 (10 g & sdot;m-2) and P15 (15 g & sdot;m-2) treatments were conducted, and the biomass, photosynthetic pigment, soil microenvironment and core bacterial function were investigated. Results showed that P additions reduced soil pH and organic carbon contents, decreased bacterial alpha-diversity and microbial network complexity, whereas enhanced ammonium nitrogen, nitrate nitrogen and available phosphorus contents, along with acid phosphatase and catalase activities, strengthened fungal network stability and increased the absolute abundance of Cupriavidus taxa, ultimately improved the pigment contents and biomass of seedlings, which the P10 treatment was the best. P10 treatment upregulated the expressions of abfA, amyA, manB, xylA, rbcL, smtA, nxrA, nifH, amoA1, nasA, gcd and phnK genes, boosted the contents of estrone, estriol, 17 alpha-hydroxyprogesterone, docasahexaenoic acid and prostaglandin F2 alpha, simultaneously decreased nucleotide-related metabolite contents in rhizosphere soil. Furthermore, Cupriavidus basilensis-10 identified as keystone strain enhanced the AP content and ACP activity in vitro, increased the photosynthetic pigment and leaf AP contents, plant height and biomass of P. chinense Schneid seedlings. These findings indicate that P10 treatment promotes the growth by improving microbial function and recruiting Cupriavidus basilensis-10 strain in rhizosphere soil of P. chinense Schneid seedlings.

Fine roots (diameter ≤ 2 mm) play a critical role in regulating soil organic carbon storage and nutrient cycling in forest ecosystems. However, the variability in fine root biomass, production, and turnover rates across different forest types remains poorly understood. This study investigates fine root dynamics, including biomass, distribution, and turnover, across four major monoculture plantation forests in subtropical China: Chinese fir (Cunninghamia lanceolata (Lamb.) Hook), Masson pine (Pinus massoniana Lamb.), Chinese sweet gum (Liquidambar formosana Hance), and camphor tree (Cinnamomum camphora (L.) J. Presl). Using a sequential coring method, soil samples were collected monthly to monitor live and dead fine root biomass across different soil depths (0–15 cm, 15–30 cm, 30–45 cm, and 45–60 cm). Fine root production and turnover rates were estimated using three methods: Max–Min, Integral and Decision Matrix. The results showed that fine root biomass was highest in the camphor tree forest (1.96 t ha−1), followed by Masson pine (1.12 t ha−1), Chinese fir (0.89 t ha−1), and Chinese sweet gum (0.83 t ha−1). Approximately 90% of the total fine root biomass was composed of live roots across all forest types, highlighting their significant role in nutrient uptake. Both live and dead fine roots were predominantly concentrated in the upper 0–30 cm soil layer, with a notable decline in biomass in deeper layers. Fine root biomass production was highest in the camphor tree forest (2.66–2.90 t ha−1 a−1), followed by Masson pine (1.16–1.83 t ha−1 a−1), Chinese fir (0.87–0.97 t ha−1 a−1), and Chinese sweet gum (0.87–0.93 t ha−1 a−1). Turnover rates were highest in the camphor tree forest (1.25–1.36 a−1), followed by Masson pine (0.96–1.51 a−1), and both Chinese fir and Chinese sweet gum (0.94–1.05 a−1 and 0.97–1.04 a−1, respectively). This study identifies significant differences in fine root dynamics among subtropical forest types, providing baseline data critical for optimizing forest management, particularly in urban and peri-urban areas. These insights can enhance reforestation efforts, ecosystem resilience, and sustainable forest productivity.

Understanding changes in water quality, microbial communities, and community functions is crucial for sustainable ecological management. This study evaluated water quality along a riverine gradient in the Taojia River, as part of a broader ecological restoration initiative guided by a comprehensive scientific research project for the river. Following these efforts, the aquatic ecosystems of the basin were evaluated post-treatment, integrating both water quality indicators and microbial diversity analyses. The results indicated that water quality met Class IV standards (Environmental Quality Standards for Surface Water (GB3838-2002), BOD5 reached its highest value during the wet season at 4.8 mg/L, CODMnpeaked at 12.3 mg/L during the normal season. DO levels were highest during the normal season at 8.4 mg/L, and EC reached 325 mu S/cm in the wet season. Water quality showed significant variation across four land use areas (A1-A4) along the Taojia River. A1 (mining area) experienced the highest pollution levels. A4 (orchard area) showed increased turbidity in the wet season and a higher pH in the dry season. A2 (agricultural area) and A3 (road area) had less impact on water quality, with smaller seasonal variations. Microbial diversity analysis revealed that Proteobacteria was the dominant phylum, with relative abundance varying seasonally: 45 % in the dry season, 52 % in the wet season, and 48 % in the normal season. Significant positive correlations were found between microbial community structure and TP, CODMn, and BOD5, while pH, EC, and DO showed negative correlations, highlighting the crucial role of seasonal variations in these environmental factors on microbial distribution. Changes in microbial communities could influence water purification by modulating functional genes involved in nutrient cycling, organic matter degradation, and pollutant removal. These functional shifts reflected the ecosystem's capacity to respond to environmental stressors and maintain water quality. This study was innovative in its integrated assessment of microbial diversity and water quality across multiple land use types following ecological restoration, providing novel insights into how land use and seasonal dynamics jointly influence riverine ecosystem health. Our findings provide ecological insights into sustaining water quality and guiding river management practices following ecological restoration facilitated by ecological water replenishment.

Soil active nitrogen (N) fractions are essential for plant growth and nutrient cycling in terrestrial ecosystems. While previous studies have primarily focused on the impact of vegetation restoration on soil active nitrogen in karst ecosystems, the role of microclimate variation in rocky desertification areas has not been well explored. This study investigates soil active nitrogen fractions and key biotic and abiotic factors across four grades of rocky desertification—non-rocky desertification (NRD), light rocky desertification (LRD), moderate rocky desertification (MRD), and intense rocky desertification (IRD)—within two distinct microclimates: a dry-hot valley and a humid monsoon zone in the karst region of Guizhou Province, China. We evaluate soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), soil nitrate nitrogen (NO3−-N), ammonium nitrogen (NH4+-N), microbial biomass nitrogen (MBN), soluble organic nitrogen (SON), and plant diversity. Results showed that SOC, TN, and TP were significantly higher in IRD areas. Soil NO3−-N, MBN, and SON initially decreased before increasing, with consistent MBN growth in the dry-hot valley. NH4+-N did not differ significantly under NRD but was higher in the dry-hot valley under LRD, MRD, and IRD. The dry-hot valley had higher MBN and SON across most desertification grades. Microclimate significantly influenced soil active N, with higher levels in the dry-hot valley under LRD and MRD conditions. Plant diversity and regeneration varied markedly between the microclimates. In the dry-hot valley, Artemisia dominated herbaceous regeneration, especially in MRD areas. Conversely, the humid monsoon zone showed more diverse regeneration, with Artemisia and Bidens prevalent in MRD and NRD grades. Despite declining plant diversity with desertification, the humid monsoon zone displayed greater resilience. These findings highlight the role of microclimate in influencing soil nitrogen dynamics and plant regeneration across rocky desertification gradients, offering insights for restoration strategies in karst ecosystems.

Invasive exotic earthworms have been identified as a major ecological threat to forest ecosystems in the Great Lakes region, affecting soil structure, nutrient cycling, and biodiversity. Understanding key biological parameters like body length, weight, growth rate, and regeneration patterns in these earthworms is essential for elucidating their life cycle and ecological impacts on terrestrial ecosystems. In this study, an earthworm survey was conducted in the Huron Mountains of Michigan’s Upper Peninsula. The earthworms were captured from sampling quadrats, identified to species, and their body mass (dry weight) and body length measured. This study established length–weight relationships (LWRs) for invasive exotic earthworm species found in this area. Such relationships elucidate resource allocation and adaptations to different habitats, in turn helping to predict the spread and persistence of these invasive species. Three invasive earthworm species were found in the studied forests: Dendrobaena octaedra, Aporrectodea longa, and Lumbricus terrestris. Lumbricus terrestris exhibited the largest size (X̅ = 60.4 mm long; X̅ = 0.254 g), while D. octaedra was the smallest (X̅ = 25.5 mm long; X̅ = 0.012 g). The LWR regression equations were: W = 0.00001L2.135 for D. octaedra; W = 0.000001L2.816 for A. longa; and W = 0.000003L2.618 for L. terrestris. These findings highlight differences in growth patterns that may be influenced by forest composition and micro-environmental factors. At the same time, earthworms not only reflect environmental conditions but also shape them, as the composition of the worm community can in turn influence forest ecosystem structure and function. This study provided valuable insights into the biological characteristics of invasive exotic earthworms and their potential impacts on North American forest ecosystems.

Although genetic diversity and species diversity in a community often covary, the direction and strength of the covariation vary. However, this variation in the relationship of these two diversities is poorly understood. Here we investigated the role of host‐specific herbivores in generating species–genetic diversity relationship in plant communities. We quantified host specificity for Fagaceae plants–acorn weevil bipartite networks in a subtropical forest and modeled the effect of weevil herbivory on the relationship. The results showed a consistently negative relationship between Fagaceae species diversity and the genetic diversity of the dominant species, Lithocarpus glaber . Our analysis showed this negative relationship arose from a positive effect of weevil host‐specificity on Fagaceae plant richness on the one hand and the negative effect of weevil host‐specificity on the genetic diversity of L. glaber on the other hand. This latter negative effect was possibly due to differentiated selection of weevils on different genotypes of L. glaber . Our study highlights the importance of considering trophic interactions and herbivore host‐specificity in explaining the species–genetic diversity relationship.

AimDispersal of plant propagules and their genes is crucial for plant responses to landscape heterogeneities, yet the mechanisms behind this dispersal remain unclear. Ficus species depend on wind-borne fig wasps for pollination, but research on airflow effects on Ficus genetic structure has produced conflicting results. Our study aims to clarify the role of wind in shaping the genetic structure of such plants with wind-borne insect pollinators by examining how geomorphological complexity interacts with air movements to influence genetic structures. LocationSouthwest China: Sichuan, Yunnan, Guangxi and Guizhou provinces. TaxonFicus tikoua Bur., Ficus, Moraceae. MethodsWe sampled 56 F. tikoua sites across southwest China, characterised by high geomorphologic complexity. River basins and predominant winds were visualised across the sampled regions. Wind connectivity between sampled sites during the main pollination season was modelled based on hourly daily wind data. The maternal and biparental genetic structure of sites were reconstructed using chloroplast DNA (cpDNA) and nuclear SSR (nuSSR) markers. Links between genetic structure, location, and wind parameters were estimated by Mantel or partial Mantel tests. ResultsThe plant's maternal genetic structure was defined by river systems, with two distinct cpDNA groups located in the Yangtze and Pearl River basins, respectively. The boundaries for nuclear variation were less clearly delimited geographically. Sites with mixtures of nuSSR groups were concentrated where prevailing winds arrived from several directions. Stronger between-site air flows increased nuSSR geneflow and genetic similarities, while populations receiving more wind flow were also more genetically variable. Main ConclusionsOur study reveals how plant gene dispersal reflects air and water movements that in turn respond to geomorphologic complexity, thereby directly demonstrating the effects of wind on gene flow of plants with wind-borne insect pollinators. Wind data matching pollinator flight times and large sample sizes are crucial for testing wind effects.

Closely related and co-distributed species usually share a common phylogeographic history, but it remains unclear whether ecologically interacting species can respond synchronously to historical climate changes. Here, we focused on a fig-pollinator mutualism comprising Ficus pumila var. pumila and its obligate pollinators (morphospecies Wiebesia pumilae), and collected samples across most of their distribution ranges. We employed cytoplasmic DNA sequences and nuclear microsatellite loci to reveal the species composition within the pollinators and to test whether the two mutualists exhibited similar postglacial phylogeographic patterns. We identified three cryptic pollinator species, with two dominant cryptic species exhibiting parapatric distributions in the northern and southern parts of the plant's range, respectively. Similar current spatial genetic structures were detected in the two dominant cryptic pollinator species and the host plant, with both showing eastern and western genetic clusters. Moreover, evidence for postglacial expansion was found for all three species, and their potential refugia during the Last Glacial Maximum were located in the eastern and western parts of their distribution ranges. These results suggest synchronous responses to historical climate changes. Our study demonstrates congruent phylogeographic patterns between obligate mutualists and highlights the role of biogeographic factors in shaping the current biodiversity across trophic levels. (sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(Ficus pumila var. pumila)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)((sic)(sic)(sic):(sic)(sic)(sic)(sic)(sic)(sic)Wiebesia pumilae)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)DNA(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)3(sic)(sic)(sic)(sic),(sic)(sic)2(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)2(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic),(sic)2(sic)(sic)(sic)(sic)(sic).(sic)(sic),(sic)(sic)(sic)(sic)2(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

Soil multifunctionality is essential for the enhancement of soil carbon sequestration, but disturbances such as thinning practices can influence soil microbial activity and carbon cycling. Microbial residues, particularly microbial residue carbon (MRC), are important contributors to soil organic carbon (SOC), but the effects of thinning intensity on MRC accumulation remain poorly understood. This study evaluated the impact of four thinning treatments-control (CK, 0%), light-intensity thinning (LIT, 20%), medium-intensity thinning (MIT, 30%), and high-intensity thinning (HIT, 45%)-on soil multifunctionality in Chinese fir plantations five years after thinning. Soil nutrient provision, microbial biomass, enzyme activity, and microbial residue carbon were assessed. The results showed that thinning intensity significantly affected soil nutrient provision and microbial biomass, with MIT and HIT showing higher nutrient levels than CK and LIT. Specifically, MIT's and HIT's total nutrient provision increased by 0.04 and 0.15 compared to that of CK. Enzyme activity was highest in LIT (+0.89), followed by MIT (+0.07), with HIT showing a decline (-0.84). Microbial biomass, including bacterial PLFAs (B-PLFAs), fungal PLFAs (F-PLFAs), microbial biomass carbon (MBC), and nitrogen (MBN), was highest in CK and MIT, and lowest in HIT, with MIT showing a 0.13 increase compared to CK. Microbial residue carbon (MRC) accumulation was positively correlated with soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), and easily oxidized organic carbon (EOC). The highest MRC content in the 0-20 cm soil layer was observed in MIT and CK (10.46 and 11.66 g/kg, respectively), while the MRC in LIT and HIT was significantly lower, reduced by 24% and 12%, respectively. These findings highlight the significant role of thinning intensity in microbial activity and carbon cycling. Medium-intensity thinning (MIT, 30%) was identified as the most effective approach for promoting microbial biomass and enhancing carbon cycling in Chinese fir forest soils, making it an optimal approach for forest management aimed at increasing soil carbon sequestration.

Fertilizer management in artificial mixed systems is generally regarded as an efficacious approach to enhance soil fertility and sustain soil health. Nevertheless, research on the impacts of incorporating 600 g biochar (BC) with 1500 g organic fertilizers (OF) in the subsoil on the functional characteristics of short-term soil nutrient cycling in artificial mixed woodland soils remains scarce. This study investigated the effects of BC, OF, and (600 g BC + 1500 g OF) their mixture (OFBC) on soil properties and microbial functions in Cyclobalanopsis glauca and Pinus massoniana plantations. The results indicated that, compared to the control group, the contents of soil organic carbon (SOC) and total phosphorus (TP) increased by 248.33 % and 199.37 %, respectively, after the application of OFBC. Under the treatment of organic fertilizer (OF), the content of total nitrogen (TN) increased by 292.30 %. Metagenomic analysis revealed that BC-OF synergy (1) Upregulated C-fixation genes (e.g., cbbL): but suppressed C-degradation (celB, GAM1) and CH4-metabolism genes (pmoA, mmoX), promoting C-sequestration; (2) Enhanced N-cycling gene abundance (e.g., nifH, hao, nosZ), accelerating N-turnover efficiency beyond additive effects. Soil pH and beta-glucosidase activity (increased by 1255.52 %) were key mediators of microbial functional shifts. The study provides critical insights into leveraging organic amendments to enhance ecosystem services while advancing sustainable forestry practices.

Asian rainforests are a biodiversity hotspot and are dominated by dipterocarps. Thus, protecting endangered dipterocarp species living on the distribution boundary of dipterocarps is a central factor in maintaining the range of Asian rainforests. Despite the perceived conservation priority of these species, we know little about how they became endangered and how they have adapted to marginal habitats. Here, we focused on the population genomics of Hopea chinensis, an endangered species narrowly distributed at the northern limit of dipterocarps, to (1) reveal its demographic history and infer factors contributing to endangered status; (2) evaluate the genetic consequences of its small remnant population; and (3) identify key genes associated with its adaptation. We found drastic population declines after the Last Glacial Maximum, suggesting the role of human disturbances in the endangered status. Despite high levels of inbreeding, we detected only 441 derived deleterious and 337 derived major-effect mutations, which were not significantly enriched in any KEGG pathway, providing evidence of low genetic loads. Furthermore, selective sweep analysis showed 12 genes associated with cold and drought tolerance and plant defense and immunity. Comparative genomics identified 125 specific and 30 lost gene families in the genome of H. chinensis, many of which were relevant to the responses to biotic and abiotic stresses. Our findings, therefore, reveal the genomic characteristics linked with the endangered status and adaptations for H. chinensis. Together with the population genomic results from two other dipterocarp species, we highlighted the necessity to establish nature reserves to prevent further human disturbances and to comprehensively describe the mutualistic and antagonistic networks associated with endangered dipterocarp species to guide in-situ and ex-situ conservation.

Soil organic carbon (SOC) plays a critical role in regulating the global carbon (C) cycle, with forest soils serving as significant C sinks. Soil aggregate stability and the distribution of SOC in different aggregate fractions would be affected by different forest types. In this study, we investigate the distribution and dynamics of SOC within different soil aggregate fractions across three main forest types in the Huron Mountains, Michigan, USA: white birch–eastern hemlock mixed forest, eastern-hemlock-dominated forest, and sugar maple forest. We hypothesize that variations in species composition and soil depth influence SOC storage and aggregate stability through mechanisms such as root interactions, microbial activity, and soil structure development. Soil samples were collected from three depth intervals (0–20 cm, 20–40 cm, and 40–60 cm) and analyzed for aggregate size distribution and SOC content. The results showed that aggregate size distribution and SOC stocks differ significantly across forest types, with the white birch–eastern hemlock mixed forest exhibiting the highest proportion of large aggregates (>1.0 mm), which contribute to more stable soil structures. This forest type also had the highest total aggregate mass and mean weight diameter, indicating enhanced soil stability. In contrast, sugar maple forest displayed a greater proportion of smaller aggregates and a lower macroaggregate-to-microaggregate ratio, suggesting fewer stable soils. SOC stocks were closely linked to aggregate size, with macroaggregates containing the highest proportion of SOC. These differences in SOC distribution and soil aggregate stability can be attributed to several underlying mechanisms, including variations in plant root interactions, microbial activity, and the physical properties of the soil. Forests with diverse species compositions, such as the white birch–eastern hemlock mixed forest, tend to support more complex root systems and microbial communities, leading to improved soil aggregation and greater SOC storage. Additionally, forest management practices such as selective thinning and mixed-species planting contribute to these processes by enhancing soil structure, increasing root biomass, and promoting soil microbial health. These interactions play a crucial role in enhancing C sequestration and improving soil health. Our findings emphasized the importance of forest composition in influencing SOC dynamics and soil stability, offering insights into the role of forest management in C sequestration and soil health. This study provided a reference to a deeper understanding of SOC storage potential in forest ecosystems and supports the development of sustainable forest management strategies to mitigate climate change.

Microbial necromass nitrogen (MNN) is increasingly recognized as a major source of soil N, playing a crucial role in N sequestration and sustaining N balance. However, quantitative data on the contribution of MNN to total N and its relationship with soil multifunctionality (SMF) in karst plantation ecosystems remain lacking. In this study, MNN (measured via amino sugar analysis) and SMF (calculated using the mean value method) were determined across five plantations and unafforested land (control) in the Wuling Mountains of subtropical China. The soil MNN content ranged from 1.02 to 1.67 g kg(-1), contributing 53.8% to 75.4% of the total N, with Cinnamomum camphora pure forest exhibiting the highest values among all stand types and control. The afforestation of Cinnamomum camphora enhanced soil nutrient provision, microbial activity, and biomass, increasing SMF by 54% compared to the control. The soil functional parameters were generally higher in the organic horizon than in the topsoil and subsoil, and the contribution of MNN to total N was greater in the subsoil. Enzyme stoichiometry ratios indicated that microbial P limitation was prevalent in both plantation and control soils, with MNN content positively correlated with C/P and N/P ratios (p < 0.001). Increases in MNN were closely associated with SMF, encompassing nutrient provision, microbial activity, and biomass, with available N (AN) being a key predictor of MNN accumulation. The partial least squares path model revealed that nutrient provision contributed positively to MNN accumulation, and AN had a direct effect path coefficient of 0.72 on it (p < 0.01). This work underscored the critical role of MNN in contributing to N sequestration and its potential to support ecosystem functioning in the karst region.

Some fig species introduced outside of their native range have become invasive when colonized by their obligate pollinating wasps, but how these pollinators migrated and adapted to novel environments are less studied. Here, we focus on Eupristina verticillata, the obligate pollinating wasp of an invasive fig tree species (Ficus microcarpa), to uncover its demography and the molecular basis for adaptations to novel environments. We find that only one of the three cryptic species colonized in the sampling locations outside of its native range. This dominant cryptic species migrated simultaneously from the native range to the Americas and to the Mediterranean c. 130 years ago. Moreover, selective sweep analyses reveal several positively selected genes associated with adaptations to the nonnative range. Genome-wide association detect a nonsynonymous substitution in a dopamine N-acetyltransferase gene significantly linked with brood size. Our study outlines the route to colonization and genetic adaptations of an invasive mutualism.