Aims Plant sexual systems is an important reproductive role that affects plant mating, genetics, evolution, and species distribution. They are classified into three categories based on the floral organ's pistil and stamen arrangement: hermaphroditism, dioecy, and monoecy. Methods This article takes forest communities in Daiyun Mountain (elevation 900-1600 m) as the research object, analyzing changes in the quantitative characteristics of woody plant sexual systems and investigating their correlation with environmental factors via Mantel correlation analysis. Important findings The study area encompassed 85 woody plant species, with 49 hermaphroditic (57.6%), 26 dioecious (30.6%), and 10 monoecious (11.8%) species. Altitudinal increase led to a significant rise in the number of hermaphroditic and dioecious individuals, with no significant change in their species ratio, while monoecious individuals' number and species ratio significantly declined. The Shannon Wiener index and Pielou evenness index for sexual systems generally decreased with altitude, whereas the Simpson dominance index remained stable. Effective phosphorus and soil temperature were identified as the primary drivers of altitudinal changes in sexual systems characteristics. In conclusion, the quantitative characteristics of the sexual systems of woody plants on the altitudinal gradient of Daiyun Mountain showed significant differences, and the altitudinal distribution of the sexual systems was highly sensitive to environmental changes, indicating that plants adapt to environmental changes by regulating the composition of their reproductive systems, thereby ensuring the continuous survival and reproduction of their populations.

Abstract Aims With climate change, extreme drought events occur frequently around the world, and there is an urgent need to understand the resilience and influencing factors of trees after extreme drought. Methods Seven dominant tree species in karst evergreen and deciduous broad-leaved mixed forest in Guilin, Guangxi were selected to analyze the dynamic differences of xylem water transport function and its correlation with xylem characteristics and environmental factors at the end of extreme drought and after drought. Important findings (1) At the end of extreme drought, the percentage loss of xylem hydraulic conductivity (PLC) of all tree species except Cinnamomum camphora was higher than or close to 50%, and the highest was 87.92%.PLC of all species decreased linearly with the increase of xylem saturation water content at the end of extreme drought. PLC of porous species had significant positive and negative correlations with xylem density (WD) and xylem saturation water content (SWC), respectively, indicating that xylem water storage capacity was an important factor affecting water transport function of karst trees under extreme drought. (2) PLC of Fraxinus chinensis decreased significantly for the first time in the spring of the following year after extreme drought, and the formation of new vessels may be the strategy for restoring water transport function after extreme drought. The PLC of Choerospondias axillaris and Quercus acutissima, Quercus glauca, Boniodendron minius and Machilus calcicola decreased significantly for the first time on the 3rd and 13th day after extreme drought, respectively. The refilling of embolized vessels may be the strategy to restore water transport function of these species. (3) After the extreme drought event, the PLC recovery degree of all tree species at the last 6 sampling times was significantly positively correlated with the mean saturated water vapor pressure deficit (VPD) within 3 days before the current sampling time, indicating that the degree of air dryness had an important effect on the hydraulic function recovery of karst trees after extreme drought after the soil moisture condition recovered. (4) During the recovery process after extreme drought, many tree species showed embolism degree close to or even higher than that at the end of extreme drought, and the embolism fatigue degree of annular porous wood species was higher than that of loose porous wood species.

Aims Under the background of global climate change, this study investigated the dynamic characteristics of energy fluxes in Jinyun Mountain's coniferous-broadleaf mixed forest across different temporal scales and their responses to environmental factors. Methods We selected the mixed coniferous and broad-leaved forests in Jinyun Mountains as the study area, and analyzed the long time series flux data of the mixed coniferous and broad-leaved forests in Jinyun Mountains for the years 2020, 2021, and 2023 (data for 2022 are missing) using correlation factor analysis and structural equation modeling based on the data measured by eddy correlation technique. Important findings (1) At the diurnal scale, net radiation (Rn), sensible heat flux (H), and latent heat flux (LE) exhibited unimodal trends, with their peak values occurring at 14:00 local time, and approaching near-zero values after 19:00. In contrast, soil heat flux (G) displayed a bimodal pattern, reaching its daily minimum prior to sunrise and attaining its daily maximum at 14:00 local time. (2) At the monthly scale, the influence of Rn on energy fluxes increased from April, reached its maximum in July and August, then gradually decreased. The influence of Gs on LE followed the same trend. (3) At the growing season scale, Rn was the primary influencing factor for energy flux variations. Correlation factor analysis indicated that canopy conductance (Gs) had a slight limiting effect on H but a significant limiting effect on LE. However, the plant water balance mechanism exerted the strongest influence. (4) The annual mean Bowen ratios (β) for the three years were 0.69, 0.63, and 0.76, respectively. (5) Influenced by extreme drought, the sensible heat flux at the annual scale exhibited a bimodal trend. This study analyzed the characteristics and influencing factors of energy fluxes in the Jinyun Mountain coniferous-broadleaf mixed forests, revealing the dynamic processes of energy fluxes, quantifying the impacts of environmental factors, and providing a scientific basis for assessing the response of subtropical forest ecosystems to climate change and forest conservation.

Aims Microbial nitrogen use efficiency (NUE) refers to the ratio of nitrogen used by microorganisms for growth to total organic nitrogen absorbed, which is a key regulator of the soil nitrogen cycle. The 18O-H2O method and eco-enzyme stoichiometric model are the most common techniques employed to estimate microbial NUE. However, the impact of nitrogen enrichment on microbial NUE in forest soils remains to be elucidated, which would siginificantly impede the accurate prediction of soil nitrogen supply. Methods In this study, we sampled the soils from subtropical Castanopsis faberi forests and used urea to simulate atmospheric nitrogen deposition. In total, three levels of nitrogen additions were set up, including control (CK, 0 kg N·hm–2·a–1), low nitrogen (40 kg N·hm–2·a–1), and high nitrogen (HN, 80 kg N·hm–2·a–1) treatment. The 18O-H2O method and eco-enzyme stoichiometric model were used to compare the differences in soil microbial NUE under different nitrogen enrichment levels. Furthermore, soil physicochemical properties, microbial biomass, extracellular enzyme activity, and stoichiometric imbalance were also measured to explore the factors that influence the response of microbial NUE to nitrogen enrichment. Important findings The results showed that the microbial NUE, as determined by two different methods, exhibited a decline with the increase of nitrogen enrichment. The vector angle values of different nitrogen treatments were all greater than 55°, indicating that soil microorganisms in this study area were generally phosphorus limited, but nitrogen enrichment did not exacerbate the phosphorus limitation. On the contrary, nitrogen enrichment has a significant negative effect on microbial carbon and nitrogen imbalance, and a positive correlation was observed between microbial NUE and microbial carbon and nitrogen imbalance. In summary, the nitrogen enrichment may have a detrimental effect on soil nitrogen storage in subtropical forests, highlighting the necessity to enhance soil nitrogen storage by means of regulating the soil stoichiometric balance to in these forests.

Abstract Aims This study aims to reveal the effects of climate warming on the growth and morphological characteristics of fine roots in subtropical evergreen broad-leaved forests in China. Methods An in-situ soil warming experiment was conducted at the Fujian Sanming Forest Ecosystem National Observation and Research Station. The effect of soil warming on the growth and morphological characteristics of absorptive and transport roots in evergreen broad-leaved natural forests during the rainy season (May) and dry season (November) were investigated by using the in-growth core method. Imortant findings Compared with the control, during the rainy season, the warming treatment significantly reduced the growth of absorptive roots by 41.2%, and there was no significant change in the growth of transport roots. There was no significant change in the diameter and length of absorptive and transport roots. The absorptive roots SRL and SRA were significantly reduced by 53.2% and 42.9%, respectively, and the absorptive roots RTD was significantly increased by 28.8%; During the dry season, warming treatment significantly increased the growth of absorptive roots, transport roots and fine roots. The length of absorptive and transport roots increased by 38.5% and 33.5%, respectively. However, there were no significant changes in the diameter, SRL, SRA, and RTD of absorptive and transport roots. Evergreen broad-leaved forests in mid-subtropical areas show strong adaptability to future warming. During the rainy season, fine roots exhibit higher plasticity, mainly by adjusting the characteristics of absorptive roots to reduce the effect of warming on the resource absorption and growth of fine root; during the dry season, fine roots adopt a relatively conservative defense strategy, mainly by increasing the length of absorptive and transport roots to expand resource absorption space. This study provides a scientific basis for investigating the ecological adaptation mechanisms and resource acquisition strategies of fine roots with different functions in subtropical forest ecosystems under global warming scenarios.

Aims Ecosystem reactive nitrogen (N) and phosphorus (P) inputs induced by recent industrial and agricultural development can alter soil carbon (C) storage capacity by affecting soil aggregate structure and stabilization. Currently, there is a lack of observational studies on soil aggregates modeling N deposition in the subtropics, and less attention has been paid to P-N interactions. Methods In order to investigate how ecosystem N enrichment and its interactions with P deposition affect C sequestration mechanisms in soil aggregates, N and P addition experiments were conducted for 7 consecutive years in a subtropical forest in southern China. Sample plots of four N addition types were established (control: CK, 0 kg N·hm-2a-1; N addition: LN，50 kg N·hm-2a-1; N addition: N, 100 kg N·hm-2 a-1; N and P: N+P，100 kg N·hm-2 a-1+50 kg P·hm-2 a-1). Soil properties, soil aggregates and their C, N fractions, and C, N stable isotopes of aggregates at each aggregate level were determined. Important findings Evergreen broadleaf forest macroaggregates (>250 μm) were the dominant soil aggregate size accounting for 83-87% of the total soil weight, and LN treatment increased macroaggregate formation, mean mass diameter (MWD) and mean geometric diameter (MGD), while N and N+P treatments marginally reduced soil aggregate stability (p>0.05). N enrichment in this region mainly increased aggregate C and N content by increasing aggregate C and N concentration at each grain level, and the added organic matter was mainly enriched in macroaggregates. The macroaggregates mainly added organic matter with high C to N ratio and rich δ13C abundance. Compared with low N addition, excessive N input was detrimental to soil aggregate structure stabilization and C sequestration. Under N treatment conditions, the addition of P did not significantly change the stability of local aggregates and their C, N components (p>0.05). Total soil C, N, and P contents of broad-leaved evergreen forests under N addition did not promote soil aggregate formation, and the decrease of pH significantly promoted the increase of C and N contents of aggregates (p<0.05). The results of this study increase our understanding of the mechanisms of aggregate change, and thus are important references for predicting the potential of soil C sinks in broadleaf evergreen forests and other areas with similar conditions under future N and P deposition.

Aims To investigate the effects of plateau pika (Ochotona curzoniae) disturbance on niche breadth, niche overlap, ecological response rate, and interspecific associations of dominant plant species in alpine meadows, and to provide the scientific basis for the conservation and management of alpine meadow ecosystems. Methods From July to August 2020, disturbed and undisturbed plots were established across six typical alpine meadow regions located in the south-central part of the Tibet Autonomous Region. Plant species composition, individual abundance, and distribution were recorded through field surveys and quadrat sampling methods. Levins' formula was applied to calculate species niche breadth. Pianka's index was used to determine niche overlap, while ecological response rates were computed to assess resource competition dynamics among species. Additionally, the variance ratio method combined with 2×2 contingency table chi-square tests was employed to analyze interspecific associations. Important findings The disturbance caused by plateau pikas significantly influenced the niche characteristics and interspecific associations of dominant plant species. Under disturbance conditions, broad-niche species (e.g., Kobresia pygmaea, Kobresia humilis, and Potentilla saundersiana) maintained larger niche breadths, while narrow-niche species (e.g., Lagotis crassifolia and Astragalus milingensis) exhibited significantly reduced niche breadths. Overall niche overlap values decreased under disturbance, indicating reduced competitive pressures among species. Analysis of ecological response rates revealed that species generally exhibited negative feedback mechanisms under disturbance conditions, which contributed to community stability. In contrast, positive feedback mechanisms dominated in undisturbed conditions, potentially leading to excessive expansion of certain species. Interspecific association analysis demonstrated increased positive associations and decreased negative associations under disturbance conditions, facilitating synergistic interactions and coexistence among species. Plateau pika disturbance can alter the structure and function of alpine meadow plant communities by influencing plant niche characteristics and interspecific associations, thereby promoting resource differentiation and niche differentiation among species while reducing competition intensity within the community. Therefore, moderate plateau pika disturbance may be beneficial for enhancing community stability and species diversity. In the conservation and management of alpine meadow ecosystems, it is recommended to comprehensively consider the ecological role of plateau pikas and formulate rational management strategies accordingly.

Potaninia mongolica is an important constructive species and ancient endemic species in the Alxa Desert, and it is a national secondary key protected plants in China. Investigating the characteristics of the natural communities of Potaninia mongolia and studying its community classification and the relationship between diversity and environmental factors can provide data support for the conservation and long-term monitoring of this species. In this study, the representative communities of Potaninia mongolia was selected in eastern Alxa, the community characteristics were studied by sample method, and the relationship between community species diversity and environmental factors was discussed by redundancy analysis (RDA). The results showed that: (1) A total of 48 plants species were recorded in the investigated communes, belonging to 38 genera of 14 families, dominated by Gramineae, Chenopodiaceae, Compositae and Leguminosae; The life form was dominated by annual (or biennial) herbaceous species, accounting for 33.33% of the total species, perennial herbs (25.00%), shrubs (20.83%) and half-shrubs (20.83%) had similar proportions, but the shrubs was the dominant synusia of the community; The water ecological type was mainly composed of xerophytes, accounting for 79.17% of the total species, of which strong xerophytes accounted for 35.42%, reflecting the strongly arid climatic characteristics. The floristic geographic element was dominated by Gobi species and Gobi-Mongolia species, accounting for 29.16% and 22.92%, respectively, reflecting the floristic characteristics of desert vegetation. (2)According to the life form and dominance degree, Potaninia mongolica desert in eastern Alxa was divided into three association groups: Potaninia mongolica-herbs desert association group, Potaninia mongolica+shrubs-herbs desert association group, Potaninia mongolica+shrubs desert association group, which were further divided into 13 associations. (3) Results of the RDA analysis showed that temperature and precipitation were the main factors influencing the species diversity of the community.

Aim Goosegrass (Eleusine indica (L.) Gaertn.) is one of the world's malignant weeds, a dominant weed in the cotton fields along the Yangtze River in Anhui Province. Cotton is highly sensitive to weed competition. This article aims to clarify the density competition effect of goosegrass on cotton and identifies its critical period for control, providing a theoretical basis for the integrated weed management of goosegrass in cotton fields. Methods From 2010 to 2012, two experiments were conducted at an experimental site in Anqing City, Anhui Province: the goosegrass density competition experiment and the critical control period experiment. In the density competition experiment, the cotton density was kept constant while eight different densities of goosegrass (0, 0.125, 0.25, 0.5, 1, 2, 3, and 4 plants per meter) were tested to evaluate their competition with cotton throughout its growth period. This aimed to determine the effects of varying goosegrass densities on cotton growth and yield. The critical control period experiment involved different durations of weed interference and weed-free periods (0, 2, 4, 6, 8, 10, 12, and 14 weeks after crop emergence) to gather information on how goosegrass affects cotton. Important findings As the density of goosegrass increased, the plant height gradually decreased. Compared to 0.125 plants m-1 goosegrass, the plant height of goosegrass at densities of 3 plant m-1 and 0.25 plant m-1 was significantly decreased. On average over three years, the biomass of goosegrass per unit area increased from 715 kg ha-1 (0.125 plants m-1) to 4148 kg ha-1 (4 plants m-1). This indicates that intraspecific competition among goosegrass becomes more pronounced at higher densities. In 2012, the number of tillers and biomass per plant of goosegrass gradually increased, and the height of goosegrass exceeded that of cotton during the first 12 weeks after crop emergence. With the increasing weed density, the plant height and stem diameter of cotton decreased, while the number of fruit branches and bolls per plant was significantly reduced. The single boll weight was also reduced at high densities of goosegrass, however, there is no significant change in the lint percentage. In 2012, the plant height of cotton significantly decreased at densities of 2 plant m-1 or more. The cotton stem diameter was remarkably reduced at densities of 3 plant m-1 or more in 2011 and 4 plant m-1 in 2012, respectively. Specifically, at the density of 1 plant m-1, the fruit branch numbers, the boll number per plant and single boll weight was reduced by 8.7% to 11.6%, 18.6% to 35.2% and 0.1% to 4.6%, respectively. The seed cotton yields were significantly reduced at density of 0.125 plant m-1 (2010 and 2012) and 0.25 plant m-1 (2011), with reductions ranging from 10% to 18%. The boll number per plant of cotton and the loss rate of seed cotton yields were affected by the goosegrass densities, following a hyperbolic model. It is predicted that goosegrass densities of 2.3 to 3.7 plants m-1 would result in a 50% reduction in the number of bolls per plant, while densities of 0.05 to 0.09 plants m-1 would lead to a 5% reduction in seed cotton yield. As weed infestation increased, the experiment demonstrated a gradual decline in the height and stem diameter of cotton plants. Additionally, there was a significant reduction in the number of fruit branches and bolls per plant, which led to a marked decrease in seed cotton yields, fitting well with a logistic model. Conversely, With an increasing weed-free duration, cotton plants exhibited greater height and stem diameter, along with a notable rise in the number of fruit branches, bolls per plant, and seed cotton yield. The increase in seed cotton yield with prolonged weed-free duration followed a Gompertz model. The critical period for controlling goosegrass at a density of 2.5 plants m-1 is between 35 and 83 days after cotton planting, based on a 5% yield-loss threshold.

Cadmium (Cd) contamination poses a significant threat to plant growth and ecosystem security. Elucidating the mechanisms underlying plant responses to Cd stress is critical for pollution remediation and agricultural safety. This review systematically examines Cd uptake, transport, physiological responses, and mitigation strategies in plants. Cd primarily enters plants through symplastic pathways (mediated by transporters such as Nramp and ZIP) and apoplastic pathways (e.g., cell wall adsorption and xylem transport), with its bioavailability significantly influenced by soil pH, organic matter, and microbial activity. At the physiological level, Cd stress induces reactive oxygen species (ROS) accumulation, activates antioxidant enzyme systems (SOD, CAT, APX) and chelation mechanisms (e.g., GSH, PCs, MTs), and reduces cytosolic Cd toxicity via vacuolar compartmentalization. Molecularly, transporter families such as Heavy Metal ATPase (HMA) and ATP-Binding Cassette (ABC) proteins synergistically regulate transmembrane Cd transport and detoxification processes. Practically, phytoremediation technologies utilizing hyperaccumulator plants (e.g., Salix spp. and Sedum spp.), combined with chelating agents (e.g., EDTA) and plant growth-promoting rhizobacteria (PGPR), enhance soil remediation efficiency. Additionally, low-Cd crops developed through gene-editing technologies (e.g., knockout of OsNramp5 and OsHMA3) exhibit significantly reduced grain Cd accumulation. This review provides a theoretical framework for understanding plant Cd tolerance mechanisms and offers technical references for Cd pollution control and safe crop production.

Aims The objective of this study was to explore the initial response of leaf litter production and its carbon, nitrogen, and phosphorus restitution of Cunninghamia lanceolata plantation forests in the rain area of Western China to multiple levels of nitrogen addition. Methods A short-term N addition manipulation experiment with seven levels (0 kg·hm-2·a-1; 10 kg·hm-2·a-1; 20 kg·hm-2·a-1; 40 kg·hm-2·a-1; 80 kg·hm-2·a-1; 120 kg·hm-2·a-1; and 160 kg·hm-2·a-1) was conducted to examine the effects of N addition on leaf litter production, concentrations of leaf litter carbon (C), N, and phosphorus (P), as well as their return within C. lanceolata plantation forests located on the rain area of Western China. Important findings (1) The annual litterfall production of C. lanceolata ranged from 2595.88 to 3043.98 kg·hm-2·a-1, with a bimodal monthly dynamic pattern peaking in May and August. Low nitrogen additions (N10, N40) significantly promoted the withered leaf yield, but from N80 onwards, its promotion was significantly weakened until it turned to inhibition (N120, N160). (2) The mean annual C, N, and P contents of C. lanceolata litterfall were 313.89-498.12, 10.17-22.03, and 0.13-0.30 g·kg⁻¹, respectively. the carbon content of C. lanceolata withered leaves declined with the increase of the leaves of nitrogen addition, and the nitrogen and phosphorus contents showed the opposite trend. (3) The mean annual C, N, and P return of C. lanceolata litterfall ranged from 1032.91–1205.09, 43.61–36.85, and 0.50–0.61 kg·hm-2, respectively, and the carbon, nitrogen and phosphorus return was mainly regulated by yield. The short-term study showed that low N additions significantly increased the yield and carbon, nitrogen and phosphorus restitution of cedar plantation forests, while high N additions showed some negative effects, and 80 kg-N-hm-2-a-1 was the response threshold of N additions in C. lanceolata plantation forests in the West China rainforest area.