Temporal stability of soil moisture is crucial for optimizing hydrological monitoring and understanding eco-hydrological processes. However, the driving forces from underlying surfaces are complex. Large-scale ground-based measurements are costly and difficult to implement, whereas the applicability of remote sensing products in this field remains to be validated. To address those challenges, based on in-situ soil moisture observations from stations in seven typical experimental watersheds in the United States, we utilized high-resolution (1 km) remote sensing soil moisture products and multi-source underlying surface attribute data, and comprehensively integrated the random forest (RF) and structural equation model (SEM) to analyze the spatial pattern of soil moisture temporal stability at the watershed scale, identify the dominant influencing factors, and analyze their linkage pathways. The results showed that: (1) In-situ station measurements verified the pronounced spatial heterogeneity in the temporal stability characteristics of watershed soil moisture, while the spatial wetness pattern from remote sensing products agreed well with ground-based measurements (Spearman’s rank correlation coefficients 0.50-0.90). This means that remote sensing produces can reliably characterize the spatial distribution of the mean relative difference (MRD) of temporal stability index at the watershed scale, though the temporal variation amplitude is relatively dampened. (2) Dominant controls on MRD showed a clear hierarchical structure across the underlying surface. Topography (especially elevation) exerted the most extensive and dominant influence, followed by soil properties (sand content, clay content, and bulk density), while vegetation (leaf area index) played a minor role. The dominant factors and their contributions varied among watersheds. (3) The response of MRD to underlying surface factors generally exhibited nonlinearity and threshold effects, with distinct response patterns across watersheds. MRD prediction models based on dominant influencing factors achieved favorable accuracy (R²=0.53-0.78). (4) Structural equation modeling further quantified the pathways of dominant factors. Elevation exerted a significant and dominant negative direct effect on watershed MRD. The results highlighted regional specificity in linkage pathways, and reflected strong modulation by local topography-soil-vegetation configurations. This study confirms the feasibility of using remote sensing data for watershed soil moisture temporal stability research, clarifies the hierarchical, nonlinear, and regionally differentiated nature of multi-factor synergistic effects. It provides scientific basis for optimizing soil moisture monitoring networks and developing mechanism-oriented hydrological models.

Optimized grain virtual water trade is an effective strategy to alleviate water scarcity in food supply regions through the regulation of trade structures. Through the development of an interval stochastic water resource management model platform coupled with virtual water trade optimization, we examined the effects of virtual water trade optimization on water scarcity and water systems in net virtual water export basins. The results showed that: (1) The marginal water use benefit, pollution load, and water resource endowment of sub-basins were key regulating factors in the virtual water trade optimization process. Sub-basins characterized by low marginal water use benefits, high pollution discharge, and water scarcity tend to be net virtual water importers. (2) Virtual water trade optimization would alter initial water rights allocation, with net virtual water-importing sub-basins showing significant reductions in allocated water rights and net exporting sub-basins exhibiting increased allocations. (3) Water scarcity in net virtual water-exporting basins can be mitigated through the optimization of virtual water trade. Under the optimization mechanism for virtual water trade (OP) during drought years, the total basin water scarcity was reduced by 30.22%-32.66% compared to the conventional virtual water trade mechanism (NP), indicating enhanced drought adaptation capacity in the OP-based water management scheme. Sectorally, the most significant reduction in water scarcity was observed in fisheries, while the smallest reduction occurred in planting. Sectoral water scarcity was jointly affected by water use marginal benefits and cross-section water quality controls. (4) The virtual water trade optimization mechanism enhances basin water supply capacity through coordinated cross-regional allocation based on disparities in sub-basin water resource endowments on one hand, and through reduced water demand for quality maintenance via water quality target management on the other. This was the fundamental mechanism by which water scarcity in net virtual water-exporting basins would be alleviated. (5) The virtual water trade optimization mechanism enhanced the overall basin marginal benefit by 3.59%-3.61% through redirecting water resources from sub-basins with lower marginal benefits to those with higher marginal benefits, and simultaneously expanded water supply capacity, resulting in a system benefit increase of 4.76%-4.77%.

Dissolved organic carbon (DOC) represents a crucial carbon reservoir in the global carbon cycle, serving as a carbon source for microorganisms and aquatic plants. Its concentration can reflect the input and transformation of organic pollutants, while its isotope compositions provide insights into the impacts of precipitation and land-use changes on aquatic ecosystems. Hanjiang River is the primary water source of the Danjiangkou Reservoir, which plays a pivotal role in regional water quality. Yet, the sources and transformation processes of DOC in the water bodies of the Hanjiang River Basin remain poorly understood. We collected water samples from the mainstream, tributaries, and adjacent groundwater in the Hanjiang River Basin during the wet season. DOC concentrations and δ¹³C_DOC values of water samples were analyzed. Combined with hydrochemical parameters and stable isotopes of water hydrogen and oxygen (δD and δ¹⁸O), we examined the influence of natural processes and anthropogenic activities on the DOC in the river basin. The results showed that: (1) Mean DOC concentrations were 2.34 mg·L^-1 (n=28) in the mainstream, 2.59 mg·L^-1 (n=30) in tributaries, and 1.56 mg·L^-1 (n=17) in groundwater, while mean δ¹³C_DOC values were -28.3‰, -28.9‰, and -25.6‰, respectively. (2) Soil organic matter decomposition was the primary source of DOC in the upstream natural background areas, contributing 64%-91% (with a mean of 72%) to the mainstream DOC. In contrast, domestic sewage input and internal release increasingly exerted influences on DOC sources in the middle-lower plain regions. (3) DOC degradation occurred in the reducing environment of groundwater, leading to reduced DOC concentrations and enriched δ¹³C_DOC values. These results demonstrate that the DOC sources in the upstream areas of the Danjiangkou Reservoir are predominantly controlled by natural processes, with minimal influence from anthropogenic activities and internal release, providing scientific support for water resource management in the Hanjiang River Basin.

The spatiotemporal dynamics and dominant drivers of phytoplankton communities in the Bohai Rim estuaries remain poorly understood and require urgent elucidation. Combining microscopic identification of phytoplankton and analysis of aquatic environmental factors, statistical methods including Mantel test, co-occurrence network analysis and partial least squares path modeling (PLS-PM) were adopted to explore the spatiotemporal distribution characteristics of phytoplankton community structure and identify its key influencing factors across five typical estuaries around the Bohai Rim. Results showed that water salinity ranged from 0.10‰ to 30.20‰, water temperature varied between 0.00 and 34.40 ℃. The mass ratio of total nitrogen to total phosphorus was 15-1350, indicating an overall characteristic of high nitrogen and low phosphorus. A total of eight phyla of phytoplankton were identified, among which Cyanophyta, Chlorophyta and Bacillariophyta were the dominant phyla. The dominant species included Pseudanabaena sp., Microcystis sp., and Oscillatoria sp. Phytoplankton community structure exhibited distinct spatiotemporal differentiation. Spatially, phytoplankton showed an 83.3% dissimilarity in dominant species among different salinity zones. Temporally, community structure showed obvious seasonal variation. Cyanophyta was absolutely dominant in summer, whereas Bacillariophyta prevailed in winter. Mantel tests revealed that salinity was significantly correlated with species-level community composition spatially, while water temperature had significant temporal correlations with both phylum and species-level community composition. In contrast, water nutrients showed weak correlations with phytoplankton community structure. Phytoplankton co-occurrence network analysis further confirmed that salinity was generally negatively correlated with the relative abundance of dominant species, and that the strength of interspecific correlations among phytoplankton decreased significantly in non-freshwater environments. PLS-PM analysis demonstrated that water temperature and salinity indirectly regulated chlorophyll-a concentration and phytoplankton community diversity by modulating the abundance of key phytoplankton species. Overall, phytoplankton community assembly in estuaries around the Bohai Sea was jointly driven by spatial filtering effects of salinity and seasonal variations in water temperature, whereas direct regulation by nutrients was relatively weak in this region.

Elucidating the differential responses of riparian plant dispersal traits to hydrological heterogeneity and their associations with species and phylogenetic diversity is critical for ecological restoration in riparian zones. We categorized four types of hydrological heterogeneity zones from small to large in the Three Gorges Reservoir based on the scale of hydrological variation: low elevation area and high elevation area, confluence area and non-confluence area, southern riverbank area, and northern riverbank area, fluctuating backwater area and stable backwater area. Within these four hydrological heterogeneity zones, we compared the differential responses of plant communities in terms of dispersal traits, species diversity, and phylogenetic diversity at both alpha and beta scales. The results showed that plant communities in the fluctuating and stable backwater areas exhibited significant differences in dispersal traits at both alpha and beta scales compared to other hydrological heterogeneity zones. Specifically, in the fluctuating backwater area, dispersal trait diversity showed a significant positive correlation with species richness and phylogenetic diversity, whereas no correlations were observed in the stable backwater area. These findings demonstrate that large-scale hydrological heterogeneity along the flow direction, induced by dam construction, is a dominant factor governing plant dispersal and community assembly in riparian zones. Furthermore, the results suggest that discontinuities in hydrological regimes along the flow direction may create dispersal limitations. Consequently, ecological restoration efforts in the riparian zones should prioritize enhancing hydrological and ecological connectivity between fluctuating and stable backwater areas.

Water-level fluctuations are a key driver of the composition and diversity of soil microbial communities in wetlands. However, few studies have focused on the responses of soil microorganisms to waterlevel changes in lake wetlands with different hydrological connectivity. We examined the soil physicochemical properties, vegetation, and soil microbial communities at different water levels (frequently flooded areas and unflooded area) in these two types of lake wetlands, including Honghu Lake (a shallow river-connected and gate-controlled lake) and Chong Lake (a disconnected lake) in the middle and lower reaches of the Yangtze River. We further elucidated the effects of water level fluctuations on soil microbial communities and their response mechanisms in lakes with different hydrological connectivity based on hydrological indicators including runoff volume, runoff depth, and water level. The results showed that: (1) The vegetation richness index of Honghu Lake increased with rising water levels, while Simpson index showed the opposite trend. In addition, the aboveground biomass of Chong Lake and the microbial richness indices of the two lakes increased as water levels increased. (2) The results of the NMDS analysis showed that water level changes significantly altered the vegetation community in Honghu Lake and microbial community composition in two types of lakes. Meanwhile, the number of nodes and edges in the microbial network of the unflooded area in both lakes was significantly higher than in the frequently flooded areas. (3) Runoff volume, runoff depth, nitrate, available phosphorus content, and the average degree of microbial network edges were the important predictors of bacterial community composition and richness in Honghu Lake. By contrast, daily mean water level, organic carbon content, and ammonium content were important predictors of bacterial community composition and richness in Chong Lake. (4) Structural equation modeling showed that hydrology not only directly affected aboveground vegetation communities and microbial communities, but also indirectly affected microbial communities by changing soil physicochemical properties and vegetation communities. This study can provide a microbial perspective for the scientific management and protection of wetlands with varying connectivity.

Groundwater serves as a critical driver in extremely arid regions, which influences soil carbon content of desert ecosystems. However, how soil carbon fractions vary with groundwater depth and the underlying mechanisms remain poorly understood. In this study, we analyzed the distributions of soil carbon components in sites with different groundwater depths (2.5, 4.5, and 11.0 m) at the southern edge of the Taklamakan Desert. The results showed that both coarse particulate organic carbon (cPOC) and mineral-associated organic carbon (MAOC) reached peak concentrations at the 4.5 m depth, with cPOC significantly increased by 1059.57% compared with 11.0 m and MAOC increased by 37.50% compared with 2.5 m. In contrast, no significant differences were observed in the labile and recalcitrant carbon fractions across the different groundwater depths. Groundwater depth and microbial biomass carbon were identified as the primary regulators of cPOC, while peroxidase activity and microbial biomass carbon were the key drivers for the formation and accumulation of MAOC. Mechanistic analysis revealed that groundwater depth regulates the transformation and accumulation of soil carbon fractions by altering microbial biomass carbon and peroxidase activity. This study enhances the understanding of how soil carbon pools in extremely arid desert ecosystems respond to changes in groundwater level, and provides a theoretical basis and practical guidance for water resource management and the enhancement of ecosystem carbon sink function in arid regions.

Against the backdrop of global change, nitrogen deposition and shifting precipitation regimes jointly influence ecosystem functions. Elucidating the regulatory mechanisms of nitrogen-water interactions on productivity sensitivity under varying precipitation intensities is crucial for understanding how grasslands maintain stability under future climate scenarios. We analyzed the effects and mechanisms of nitrogen and water additions, as well as their interactions, on vegetation productivity sensitivity based on a six-year (2017-2022) manipulative experiment in a temperate typical steppe of Inner Mongolia. The experimental design comprised factorial N addition at 10 g N·m^-2·a^-1 and water addition totaling 80 mm·a^-1, with the latter implemented under two precipitation event-size regimes: a low-intensity regime (2 mm per event applied 40 times annually) and a moderate-intensity regime (10 mm per event applied 8 times annually). The results showed that only the combined treatment of low-intensity water addition and N addition significantly enhanced vegetation productivity sensitivity. In contrast, water addition alone (both low and moderate-intensity), N addition alone, and the combination of N addition with moderate-intensity water addition exerted no significant effects on productivity sensitivity. These findings demonstrate that grassland productivity sensitivity is jointly regulated by the synergistic interaction of N and water additions, highlighting the pivotal role of precipitation event size in maintaining ecosystem functioning. Our study provides empirical evidence supporting the maintenance of ecosystem stability under global change.

Alpine grasslands constitute a key ecosystem for water conservation and regional hydrological regulation on the Qinghai-Tibet Plateau. As typical bioturbation agents, small burrowing mammals including plateau pikas and plateau zokors play a crucial role in regulating water and soil substance transport by reshaping surface-groundwater connectivity. However, the underlying mechanism remains poorly understood. We review the research progress on the ecohydrological effects of burrowing mammals in alpine grasslands. Targeting two major bottlenecks in current water transport mechanism analysis and model dynamic representation, we clarify the research framework consisting of cave structural characteristics, multi-factor coupling mechanisms, multi-scale effect deduction, and research method integration. This study extracts the dual and nonlinear characteristics of hydrological effects induced by bioturbations under the regulation of rainfall and population thresholds, as well as the spatial scale dependence across point, slope, and watershed scales. On this basis, we propose to establish an integrated “space-sky-ground-well” three-dimensional monitoring technology system and a cross-scale observation and simulation integration framework, and develop a dynamic ecohydrological model with explicitly coupled biological activity modules. Such efforts provide a critical scientific basis for evaluating water resource effects and implementing adaptive management of degraded alpine grasslands under the context of climate change.

Clausena dunniana, a dominant species in the subtropical karst forests, is widely distributed across all successional stages, making it an ideal indicator species for understanding forest dynamics. In this study, we investigated C. dunniana populations across different successional stages in the Maolan National Nature Reserve, including tree-shrub mixed forest (SC), secondary growth forest (SG), and old-growth forest (OG). By integrating static life tables, survival analysis, time-series forecasting, and competition indices, we analyzed population structure and dynamics. The results showed that: (1) Population age structure varied across successional stages, with SC exhibiting a typical increasing reverse J-shaped pattern, SG showing a pyramid-shaped distribution, and OG displaying a spindle-shaped structure with insufficient recruitment of young individuals. (2) The population dynamic index (V_pi) revealed the highest theoretical growth potential in SC (53.03%), but the actual regeneration index (V_pi′) under disturbance approached zero across all stages (SC: 0%, SG: 1.01%, OG: 3.29%). (3) Survival curves conformed to Deevey Type II in SC and SG, and shifted to Deevey Type I in OG. (4) Survival analysis demonstrated that mortality risk in SC was concentrated in early life stages, increased gradually with age in SG, and peaked during middle to late life stages in OG. (5) Time-series projections indicated a long-term decline in population size across all successional stages due to insufficient recruitment. (6) Interspecific competition emerged as the dominant limiting factor, with competitive intensity decreasing as diameter at breast height increased, and reaching the peak at the sapling stage. By elucidating the population dynamics of C. dunniana and highlighting the constraining effects of competitive pressure on population development in the fragile karst habitat, our results provide a scientific foundation for forest restoration and biodiversity conservation.

To understand the responses of dominant species across different plant life forms in forests to nutrient addition, we conducted a field manipulative experiment with four nutrient addition treatments, including CK, N10, P2, and N10P2. We measured the stoichiometric traits and homeostasis of dominant tree, shrub and herb species, namely Betula platyphylla, Larix gmelinii, Alnus sibirica, Rhododendron dauricum, Elymus dahuricus and Carex tristachya. The results showed that: (1) Nitrogen addition increased leaf N content of the six dominant species, and phosphorus addition increased the leaf P content of these species, and simultaneous addition of nitrogen and phosphorus increased leaf N content of B. platyphylla, L. gmelinii, R. dauricum and C. meyeriana, with no significant effect on the leaf N content of P. lasiocarpa and L. chinensis, while also increased the leaf P content of R. dauricum, C. meyeriana, and L. chinensis, but did not affect L. gmelinii and P. lasiocarpa. (2) The variation of foliar N∶P ratios across the six species was jointly influenced by the changes in leaf N and P content, with N being the main limiting factor. (3) Under short-term nutrient addition, the stability of the three plant life forms (trees, shrubs, and herbs) of the Greater Khingan Mountains forest community showed the order: trees>shrubs>herbs. This study provides a new perspective on nutrient management and community succession predictions in boreal forests and offers a theoretical basis for the nurturing of boreal forests.

Investigating the effects of shading on the growth of Firmiana danxiaensis seedling during ex-situ reintroduction and evaluating comprehensive seedling quality will provide scientific evidence for the ex-situ conservation. With F. danxiaensis seedlings from afforestation, we conducted a single-factor experiment with different treatments including open space (CK), shading on all sides (S₁), shading on the west side (S₂), shading on the east side (S₃), and shading on two sides (S₄). We measured growth indices (diameter at ground level, seedling height), leaf morphological traits (leaf number, leaf area, leaf thickness, petiole length, and petiole width), chemical traits (leaf carbon (C), nitrogen (N), and phosphorus (P) contents, C∶N, C∶P, N∶P ratios, and δ¹³C), and photosynthetic traits (SPAD value, maximum photochemical efficiency of photosystem Ⅱ F_v/F_m, photosynthetic performance index, and intrinsic water use efficiency (iWUE). We further comprehensively evaluated the responses of F. danxiaensis seedlings to shading. The results showed that: (1) Shading had a greater impact on seedling height (0.67-0.97 m, P<0.05) than on diameter at ground level (8.77-10.70 mm). The growth of seedling showed an allometric growth relationship (P(α=1)<0.01). (2) Shading significantly altered petiole length and width (P<0.05) and induced significant differences in leaf C, N, and P contents, C∶N, C∶P and N∶P ratios, and δ¹³C (P<0.05). However, only the SPAD value showed significant differences among photosynthetic traits, with the value being higher in S₁ than that in CK (P<0.05). (3) Diameter at ground level displayed a significant positive correlation with seedling height (P<0.05), while leaf phosphorus concentration was positively correlated with all the measured leaf morphological traits, including leaf number, leaf area, leaf thickness, and petiole length (P<0.05). Similarly, the F_v/F_m was positively correlated with iWUE (P<0.05). Conversely, SPAD values presented significant negative correlations with leaf thickness, petiole width, and leaf C∶N (P<0.05). Leaf δ¹³C had significant negative relationships with leaf nitrogen concentration, C∶P, and N∶P (P<0.05). (4) The comprehensive quality index of shaded seedlings ranged from 0.40 to 0.48, with all shading treatments yielding higher values than the open habitat. East-side shading treatment was the most beneficial for seedling growth. Moderate retention of shaded environments in ex-situ conservation practices for F. danxiaensis can effectively enhance seedling growth, leaf photosynthetic capacity, and seedling quality.

Under the background of global change, understanding the effects of nutrient addition on soil physicochemical properties and plant functional traits in coastal wetlands would provide a scientific foundation for the conservation and management of coastal wetland vegetation. Using field-manipulative experiments in the coastal wetlands of the Yellow River Delta, we investigated the soil physicochemical properties and changes in plant growth and physiological traits under the addition of different nutrients. Nutrients were applied annually from May to mid-August, with N, P, and K at a rate of 10 g·m^-2·a^-1 each. The results showed that N addition significantly increased soil nitrate (NO₃^--N), available nitrogen (AN), and available Cu by 98.6%, 98.7%, and 18.6% (P<0.05), respectively. Nitrogen addition significantly increased leaf area by 31.4%, canopy leaf area index by 29.2%, plant height by 13.6%, and increased leaf N, K, and Zn contents by 9.4%, 15%, and 30.7% (P<0.05), while it significantly reduced leaf Mg and Na contents by 21.6% and 48%, respectively (P<0.05). Phosphorus addition significantly increased soil TN by 33.3% and leaf TP by 17.7% (P<0.05), while it significantly decreased canopy leaf area index and Na content by 23.3% and 46.6%, respectively (P<0.05). Potassium addition significantly increased soil NO₃^--N, AK, and plant height by 72.9%, 52.3%, and 11.8%, respectively (P<0.05). Potassium addition also significantly decreased leaf Mg and Na contents by 24.2% and 60.3%, respectively (P<0.05). Additionally, redundancy analyses between plant functional traits and soil physicochemical properties revealed that soil N, P, K contents, pH, and conductivity significantly influenced plant growth and physiological indices. Therefore, environmental changes induced by exogenous nutrient inputs substantially impacted soil physicochemical properties and plant functional traits in the coastal wetland of the Yellow River Delta.

Nitrogen is one of key regulators of wetland methane (CH₄) emissions. However, how increased input of different nitrogen forms in winter affects CH₄ production and oxidation in high and low tidal zones of estuarine wetlands has been poorly quantified. In this study, soil samples were collected from three soil layers (0-10, 10-20, and 20-30 cm) of Cyperus malaccensis marshes in the high and low tidal zones of Shanyutan in the Minjiang Estuary in winter. Soil microcosm incubation experiments were conducted under anaerobic and aerobic conditions. Based on the background nitrogen input of 21 g·m^-2·a^-1 in the Minjiang Estuary wetlands, three treatments of control (no nitrogen addition), low level addition (50 mg N·kg^-1 dry soil; 2.5 times of the background input rate), and high level addition (100 mg N·kg^-1 dry soil; five times of the background input rate) of nitrate (NO₃^--N) and ammonium (NH₄⁺-N) were set up. The responses of CH₄ production and oxidation potentials in marsh soils of high and low tidal zones to the addition of different forms of nitrogen in winter were different. After adding high-level nitrate, CH₄ production potential decreased by 95.4% in the 0-10 cm soil layer of the high tidal zone, and decreased by 83.3% in 20-30 cm soil layer of the low tidal zone. However, responses of CH₄ production potentials in the different soil layers of high and low tidal zones to ammonium addition were not significant. Addition of ammonium and nitrate did not affect CH₄ oxidation potential of the 0-10 cm soil layer in high and low tidal zones. Soil total carbon content, total nitrogen content, and C∶N ratio was the main soil factors affecting CH₄ production potential.

Cyperus esculentus is characterized by rapid growth and strong tolerance to drought and low soil fertility. However, its potential as a pioneer species for restoring desertified grasslands has received limited attention, and the effects of C. esculentus cultivation on soil fertility and the underlying mechanisms remain poorly understood. In this study, we assessed changes in soil nutrient contents, enzyme activities, soil respiration rates, microbial biomass, bacterial community structure and composition, and predicted functional potential using PICRUSt2 before and after C. esculentus cultivation. The results showed that: (1) C. esculentus cultivation increased the soil dissolved organic carbon to dissolved organic nitrogen ratio by 1.3-fold and the soil carbon availability index by 40.6%, indicating its positive impact on soil carbon availability. (2) C. esculentus cultivation increased microbial biomass nitrogen by 75.3% and protease activity by 58.8%, and elevated soil nitrate content by 13-fold, suggesting its role in enhancing microbial nitrogen immobilization and soil nitrogen mineralization. (3) C. esculentus cultivation significantly altered soil bacterial community composition, with increased relative abundances of copiotrophic taxa, including Bacteroidetes and Acidobacteria subgroup Gp1, whose relative abundances increased from 3.7% to 5.0% and from 1.4% to 7.6%, respectively. This pattern was consistent with faster nutrient turnover. In conclusion, C. esculentus cultivation in desertified grasslands can activate soil nutrients through multiple pathways, including enhancing microbial activity, improving bacterial community structure, and regulating soil carbon and nitrogen turnover, thereby facilitating soil organic matter accumulation. This study provides important mechanistic evidence for the promotion of C. esculentus cultivation in ecological restoration and soil fertility improvement in sandy semi-arid regions.

Natural secondary forests constitute the main body of forests in the mountainous areas of Beijing. An in-depth investigation on the distribution patterns and key influencing factors of soil microbial communities across different stand types and soil depths, as well as revealing how soil bacterial community diversity and cooccurrence network assembly respond to stand structure and environmental factors, is of great significance for understanding the functional maintenance and succession dynamics of warm-temperate Quercus mongolica forests. In this study, typical regional Q. mongolica natural secondary forests were selected as the research object. Soil samples from different depths (0-20 and 20-40 cm) were collected from three stand types (pure Q. mongolica natural secondary forest; mixed Q. mongolica, Populus davidiana, and Betula platyphylla natural secondary forest; and mixed Q. mongolica and Pinus tabuliformis natural secondary forest). Stand structure indicators, soil physicochemical properties, and microbial communities were measured. The results showed that: (1) Soil bacterial communities exhibited distinct stratification with soil depth. The alpha diversity indices of bacterial communities in the upper soil (0-20 cm) were generally higher than those in the lower layer (20-40 cm), with significant difference observed in the coniferous-broadleaved mixed forest (P<0.05). Among different stand types, the upper soil of the coniferous-broadleaved mixed forest had the highest bacterial alpha diversity indices (Shannon, Chao1, and Sobs indices), while the pure forest had the lowest. (2) Soil organic matter content and nitrogen content (TN and AN) were the core factors regulating the alpha diversity of bacterial communities. In the upper soil, these factors were significantly correlated with species richness (Chao1 and Sobs) (P<0.05), whereas in the lower soil, they were significantly correlated with species diversity (Shannon) (P<0.05). (3) Mixed forests constructed more complex bacterial co-occurrence networks than pure forests, exhibiting higher numbers of nodes and edges, as well as greater modularity. The mixed forest soils were enriched with more key functional taxa belonging to the phyla Acidobacteria and Actinobacteria, which acted as hub nodes and effectively enhanced the aggregation effect and ecological functioning. (4) Across all stand types, the topological parameters of the bacterial co-occurrence networks in the upper soil layer were higher than those in the lower soil layer, indicating that the upper layer is the primary carrier for the ecological functions of bacterial communities. Variations in stand types and soil factors significantly affected the topological structure of the bacterial co-occurrence networks. This study reveals the diversity and co-occurrence network assembly patterns of soil bacterial communities in different types of warm-temperate Q. mongolica secondary forests. These findings are of great significance for understanding the synergistic enhancement of ecosystem multifunctionality and provide scientific support for the maintenance and sustainable management of forest ecosystems.

Pruning is one of the commonly used tending practices in plantation management. However, the short-term effects of pruning on soil microbial dynamics remain poorly understood, which constrains the development of precise tending practices. In this study, we set four pruning treatments in a 5-year-old Pinus massoniana plantation at Fubo Forest Farm in the Guangxi Zhuang Autonomous Region, including no pruning (control, CK), light pruning (removal of branches below one-third of the dominant tree height; 1/3 pruning), moderate pruning (removal of branches below one-half of the dominant tree height; 1/2 pruning), and heavy pruning (removal of branches below two-thirds of the dominant tree height; 2/3 pruning). Soil physicochemical properties, microbial biomass, and extracellular enzyme activities were measured, and ecoenzymatic stoichiometric ratios and vector characteristics were calculated. The results showed that: (1) Pruning significantly affected soil enzyme activities and ecoenzymatic stoichiometric characteristics. Under the 1/3 pruning treatment, β-1,4-glucosidase activity, the ratio of carbon (C)-acquiring to nitrogen (N)-acquiring enzyme activities, and the ratio of C-acquiring to phosphorus (P)-acquiring enzyme activities were the highest, being 66.59%, 28.70%, and 15.56% higher than that in CK, respectively. In contrast, under the 1/3 pruning treatment, the activities of the N-acquiring enzymes β-1,4-N-acetylglucosaminidase and leucine aminopeptidase, together with the ratio of N-acquiring to P-acquiring enzyme activities, were the lowest, being 15.75%, 28.48%, and 9.64% lower than that in CK, respectively. (2) Pruning significantly affected vector angle (VA) and vector length (VL), both of which were significantly higher under the 1/3 pruning treatment than under the other treatments. Under all treatments, VA and VL were greater than 45° and 1, respectively, and VA increased with increasing VL. (3) Redundancy analysis showed that soil microbial biomass C, the microbial biomass C/N ratio, and nitrate significantly affected ecoenzymatic stoichiometric characteristics and microbial nutrient limitation. Partial least squares path modeling further showed that soil inorganic N and total potassium exerted indirect positive effects on VA by positively regulating microbial biomass. In conclusion, light pruning increased the activities of soil C- and P-acquiring enzymes, but simultaneously intensified microbial nutrient limitation. Soil microbial biomass played a mediating role in  the effects of soil chemical properties on microbial P limitation. These findings provide a theoretical reference for selecting an appropriate pruning intensity in P. massoniana plantations in the southern subtropical region of China.

Cultivating Aralia elata under larch plantations is a typical economic industry in mountainous areas of eastern Liaoning. However, the effects of A. elata cultivation on soil organic carbon and microbial communities remain unclear. We analyzed soil carbon pool components and microbial community characteristics in 0-10 cm and 10-20 cm soil layers between plots with understory planting of A. elata (experimental group) and non-planting plots (control group) in the compound ecosystem of larch plantations intercropped with A. elata in eastern Liaoning mountainous areas. The results showed that: (1) Compared with the control group, understory cultivation of Aralia elata significantly increased the contents of soil total carbon, soil organic carbon and its main components including dissolved organic carbon, particulate organic carbon and mineral-associated organic carbon. The amplitude of enhancement was higher in the 0-10 cm soil layer than in the 10-20 cm layer. (2) A. elata planting markedly increased the Simpson diversity of bacteria but decreased that of fungi. The community structure exhibited specific differentiation across different soil layers. There were significant differences among bacterial communities, whereas distinct variations of fungal communities mainly occurred in the 0-10 cm soil layer. (3) Compared with that in the control, understory A. elata planting decreased the relative abundances of bacterial phyla Acidobacteriota and Chloroflexota, and fungal phylum Basidiomycota, while increased those of bacterial phyla Pseudomonadota and Verrucomicrobiota, and fungal phylum Ascomycota. Soil organic carbon and its main components showed negative correlations with the relative abundance of Chloroflexota, but positive correlations with that of Verrucomicrobiota. This study revealed the patterns and correlations of significant increases in soil organic carbon and its main components, as well as changes in microbial community diversity and key taxa under the intercropping system of larch plantations and A. elata. Our findings provide an important theoretical basis for the coordinated ecological and economic development of this compound planting mode in Northeast China.

Fine root decomposition is a key way for plants to return carbon (C) and nutrients to the soil. The increases in exogenous nitrogen input caused by increased global atmospheric nitrogen deposition is continuously interfering with root decomposition process, thereby affecting the nutrient cycle of forest ecosystems. To explore the mechanisms underlying the effects of nitrogen addition on decomposition rates and nutrient release of fine roots across different root orders, we selected Larix gmelinii and Fraxinus mandshurica, the dominant afforestation tree species in Northeast China, as research materials. The root-order classification approach was adopted to separate fine roots (diameter ≤2 mm) into three groups: first- and second-order roots were combined as low-order roots, third- to fifth-order roots as medium-order roots, and sixth-order roots as high-order roots. There were four nitrogen treatments, including inorganic nitrogen (IN), organic nitrogen (ON), mixed inorganic and organic nitrogen (IN+ON), and a control (CK). The litterbag method was used to investigate decomposition and nutrient release of fine roots with different root orders for the two tree species. The results showed that after 350 days of decomposition, there was a significant interspecific difference in root decomposition rate between the two tree species (P<0.05), which was manifested as F. mandshurica>L. gmelinii. Nitrogen application significantly promoted root decomposition rate in both species, but there were differences in the promotion effects of different nitrogen forms. The specific manifestations were: IN had the best effect, followed by ON, IN+ON had no significant effect. There was no significant difference in the decomposition rate of each fine root order across different nitrogen treatments (P>0.05). There was a significant differentiation in nutrient release characteristics for both species. The C release rate of low-order roots was significantly lower than that of medium- and high-order roots, while the N release rate was significantly higher than that of medium- and high-order roots. In addition, nitrogen application significantly promoted the release of fine root C, but did not affect N release. Our results can help understand  the material cycle process in forest ecosystems under nitrogen deposition.

Litter decomposition is a critical component of nutrient cycling in forest ecosystems. Betula platyphylla is a dominant tree species in the Wudalianchi volcanic forest ecosystem. We investigated the eco-stoichiometric characteristics, bacterial community composition, and diversity during the decomposition of leaf litter using in situ litterbag incubation and high-throughput sequencing. The results showed that after one year of decomposition, the mass remaining of B. platyphylla leaf litter was 62.6%. Decomposition time significantly influenced carbon (C), nitrogen (N), and phosphorus (P) contents, as well as C/N, C/P, N/P ratios (P<0.05). During decomposition, the relative abundance of Cyanobacteria decreased significantly, whereas that of dominant bacterial taxa, including the phyla Proteobacteria, Bacteroidota, and Actinobacteria, as well as the genera Sphingomonas and Massilia, significantly increased (P<0.05). The relative abundances of bacterial functional groups, such as chemoheterotrophy and aerobic chemoheterotrophy, increased over time (P<0.05). Litter P content, C/P, and N/P were key factors shaping bacterial community structure. However, due to the unique nature of the volcanic lava environment, litter bacterial community was driven by both litter stoichiometry and environmental filtering. Our results provide deeper insights into the driving mechanisms of stoichiometry on litter-associated bacteria during litter decomposition in volcanic forest ecosystems.

Litter decomposition is a crucial biogeochemical process in wetland ecosystems, which significantly impacts soil fertility and carbon cycling. In this study, we conducted a 450-day in-situ field experiment in the Nanji Wetland of Poyang Lake using the litterbag method, to investigate the decomposition rates of aboveground litter and roots, as well as the dynamic changes in carbon (C), nitrogen (N), and phosphorus (P) release of three dominant plant species (Carex cinerascens, Triarrhena lutarioriparia, and Phragmites australis). The results showed that root decomposition rate (k) of all the three species was significantly faster than that of aboveground litter, and exhibited rapid decomposition during the early stage (0-90 d), with rates all exceeding 0.0017 d^-1. Throughout the decomposition process, the mean concentrations of TC and TN in aboveground litter and roots of the three species were significantly higher in the early stage compared to mid-late stages, exhibiting a net release pattern of C and N. Further, during decomposition, TP concentration of C. cinerascens showed significantly higher in aboveground litter than in roots, with C. cinerascens exhibiting significantly greater TP concentration compared to T. lutarioriparia and P. australis, while there were no significant differences in TC and TN concentrations among the three species. The aboveground litter and root decomposition rates (k) of the three species showed significant positive correlations with TC and TN concentrations, C∶P ratios, N∶P ratios. Root decomposition rates (k) were significantly negatively correlated with TP concentrations and C∶N ratios. The decomposition rate of roots exceeded that of aboveground litter, and TP concentration in C. cinerascens litter exhibited the most pronounced sensitivity to seasonal environmental variations. These findings provide critical empirical support for elucidating the decomposition patterns of dominant plant litter (aboveground and belowground) and carbon dynamics in seasonal lake wetlands.

Modern surface soil pollen assemblages serve as a bridge linking modern vegetation, climate, and paleoenvironmental reconstruction, which can reveal the mechanisms underlying ecosystem responses to environmental changes and provide a scientific basis for assessing the impacts of human activities. Here, we conducted pollen analysis on 20 surface soil samples collected at different elevations in Qingcheng Mountain, aiming to understand the associations between modern surface pollen assemblages and vegetation, as well as their indicative significance for human activities. Results showed that the surface pollen in Qingcheng Mountain was dominated by Pinus, Taxodiaceae, Castanopsis, evergreen Quercus, Cyclobalanopsis, Alnus, Betula, Pterocarya, deciduous Quercus, Ulmus, Juglans, Rosaceae, Poaceae, and Polypodiaceae. Among them, woody plant pollen accounted for an absolute advantage (91.9%), with the average ratio of arboreal to non-arboreal pollen (AP/NAP) reaching 15.9, indicating the main characteristics of subtropical forest. Comparative results of pollen assemblages between evergreen broad-leaved forests and secondary forests in low-altitude areas indicated that the pollen content of dominant evergreen broad-leaved species (Castanopsis, evergreen Quercus) in secondary forests decreased significantly, while the proportion of pollen from pioneer species (Pinus or Alnus) increased accordingly, accompanied by large enrichment of fern spores. Meanwhile, pollen concentration, AP/NAP, and E/D value (ratio of evergreen broad-leaved tree to deciduous broad-leaved tree pollen) all showed a downward trend, while the pollen diversity index increased slightly. The coordinated changes in those indicators reflect the disturbance effect of human activities on natural vegetation and indirectly confirm the effectiveness of vegetation conservation in the national reserve. Our findings provide a scientific basis for regional paleoclimate reconstruction, extraction of information on human activities in historical periods, and ecological civilization construction.

Biodiversity assessment has long been the central to ecology, biogeography, and conservation biology. The lack of baseline biodiversity information constrains refined and quantitative assessments of biodiversity at regional scales. We conducted a comprehensive survey of the Cangshan Mountain region between 2022 and 2024, with biodiversity and spatial data collected across the entire region using the “Cloud-based Scientific Survey” platform. An assessment framework based on ten indicators was developed, including ecosystem diversity, vegetation index, species richness, kernel density, nationally protected species richness, endemism, threat status, and degree of alien invasion. Employing an integrated assessment method, regional biodiversity was quantitatively evaluated based on equal-area grid cells (2 km×2 km). The current status, spatial patterns, and environmental drivers of biodiversity were evaluated, with analysis including a conservation gap assessment. Results showed that overall biodiversity indices were high (BI: 0.08-0.82), with a pattern of higher in the northern, central-southern, and central-western mid-high altitude zones and lower in the eastern and western low-altitude zones. High-value sites were primarily located in mid-altitude (2400-3300 m) forested regions, whereas low-value sites were concentrated in zones with intensive human disturbance (e.g., construction and agriculture) at lower elevations on the eastern and western sides of the region. The GAM model analysis showed that annual average precipitation, elevation, and the shortest distance to the residential area were the key factors influencing biodiversity. Mean annual precipitation showed a significant linear positive effect (P<0.001). Altitude exhibited a significant single peak effect that increased first and then decreased (P<0.001). The shortest distance to the residential area showed a significant non-linear effect (P=0.02). They collectively explained 48.8% of the variation in biodiversity. Further analysis indicated that the Cangshan Protected Area’s boundaries largely ensure effective coverage of regional biodiversity, though its internal functional zoning requires further optimization. Overall, this study offers a decision-making basis for the conservation and management of the Cangshan Protected Area.

Camellia hainanica are frequently impaired by the seasonal high temperature weather in Hainan. In this study, we investigated the effects of high-temperature stress on the physiology of five grafted cultivars of C. hainanica (1.5 years old), which were exposed to high temperature (40±2 ℃) for nine days. A total of 13 physiological indices were measured in the leaves from each cultivar. The heat tolerance of the five cultivars was evaluated comprehensively using multivariate statistical analysis. The results showed that hightemperature exposure increased the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and the accumulation of soluble protein and free proline in the leaves of all the five C. hainanica cultivars. Under high-temperature stress for 3-6 days, the growth rate of malondialdehyde (MDA) content and relative conductivity in all the five cultivars was relatively smaller compared with that of the control group. Moreover, the total chlorophyll and carotenoid contents of the five cultivars increased to a certain extent, or showed a modest decline. However, on the 9th day of treatment, the MDA content and relative conductivity in the leaves of all the five cultivars significantly increased, while total chlorophyll and carotenoid content significantly decreased. There was difference in the physiological responses to high-temperature stress among cultivars. System clustering analysis indicated that the five cultivars were classified into three distinct heat-tolerance categories: heat-tolerant (Wanhai 1), moderately heat-tolerant (Wanhai 4), and heat sensitive (Wanhai 3, Haida 1, and Haida 4). A stepwise regression analysis was performed to evaluate heat tolerance in C. hainanica using the equation: Y=2.240-1.625x11 (P=0.014, R²=0.864), where Y represents the predicted value of comprehensive evaluation score, x11 denotes the heat resistance coefficient of SOD activity. This equation can serve as a reliable and accurate method for assessing heat tolerance in C. hainanica, and SOD activity can serve as a key index for screening heat-tolerance cultivars of C. hainanica. Our results revealed the physiological mechanisms underlying the response of different C. hainanica cultivars to high-temperatures stress, providing a valuable reference for identifying heat tolerance and optimizing cultivation of C. hainanica cultivars.

Renhuai City lies within the Chishui River Basin, a national-level nature reserve for rare and endemic fish species in the upper reaches of the Yangtze River. Moreover, it is the core production area for Maotai-flavor spirits in China. Understanding the health status of the rivers is conducive to the conservation of aquatic biological resources and the sustainable development of the society and economy in this area. We conducted a quarterly investigation of phytoplankton and environmental variables at 28 sampling sites along nine rivers in 2023. The relevant taxa were used as indicator organisms to evaluate the health status of these rivers. The results showed that: (1) A total of 96 species belonging to 52 genera and 7 phyla of phytoplankton were identified, which could be classified into 23 functional groups, among which 10 were dominant groups. (2) The seasonal succession tendency of functional groups was: S2/W1/Y (spring) → G/L-O-/W1/Y (summer) → S2/W1/Y (autumn) → S2 (winter). There were significant differences in the functional group composition between winter and summer as well as between the main stream of the Chishui River and its tributaries. Water pH, unclassified land use type (Uncla), total dissolved solids (TDS), and spatial factors (PCNM1, PCNM3, PCNM9, PCNM10) were the main environmental factors driving this ecological process. (3) Although the Q_r index (an ecological index based on functional groups) indicated that these rivers as a whole were in a “general-sub-healthy” state, the P-IBI (phytoplankton-integrated biotic index)  indicated a “sub-healthy-healthy” level. This study can provide basic data and technological support for the advancement of the Yangtze River comprehensive protection.

To investigate the impact of urbanization on amphibian health status, adult male and female Chinese toads (Bufo gargarizans) were captured alive in urban central areas and rural areas of Hefei. Using morphometric measurements and abdominal venous blood sampling, we compared the differences of in body mass, body length, and the ratio of body mass to body length, percentages of various subtypes of leukocytes, the ratio of neutrophils to lymphocytes (N/L), and serum bactericidal capacity across different regions and sexes. The results showed that both urban males and females showed significantly longer body lengths than rural counterparts, while there were no regional differences in body mass and the ratio of body mass to body length. Female toads displayed lower percentages of both eosinophils and basophils compared to males in urban central areas, while the percentage of lymphocytes was higher in urban central areas than in rural areas. There were no regional variations in percentages of neutrophils and monocytes, as well as N/L. In males, none of the above-mentioned white blood cell parameters or the N/L ratio showed regional differences. Serum bactericidal capacity was significantly lower in urban central areas than in rural areas. Within the same region, there were no sex differences in body mass, body length, and the ratio of body mass to body length. In rural areas, female toads had higher percentages of eosinophils and basophils than males, while the percentages of lymphocytes were lower in females than in males, and no sex differences were found in the percentages of neutrophils and monocytes, serum bactericidal capacity, and N/L. In urban central areas, there were no sex differences in any of the above-mentioned subtypes of leukocytes, serum bactericidal capacity, and N/L. These findings suggest that in the specific selected areas, urbanization in Hefei may primarily affect the physiological adaptation and therefore the survival of female toads.

Bdelloid rotifers constitute a significant microfaunal taxon in soils. In this study, we investigated the effects of climate and soil physicochemical factors on the bdelloid rotifer community structures, with soil samples being collected from 18 sites in Northeast China (August 2024) and 19 sites in Xinjiang (September 2024). The differences in the bdelloid rotifer community structures and their relationships with environmental factors were compared between the two regions. The results showed that the species richness (36 species) and average abundance (1.15×10⁵ ind·m^-3) of bdelloid rotifers in the soil of Northeast China were significantly higher (P<0.05) than those of Xinjiang (24 species, 0.19×10⁵ ind·m^-3). A total of 21 species were identified in both regions, and the distribution of endemic species exhibited a significant ecological differentiation (15 species in Northeast China and 3 species in Xinjiang). The α diversity indices (Margalef, Shannon, Brillouin, and Simpson) exhibited significantly higher values in Northeast China than that in the Xinjiang (P<0.05). The dominant species were Rotaria sordida and Macrotrachela multispinosa brevispinosa, with dominance values of 0.26 and 0.22, respectively. The soil bdelloid rotifer community structure in Northeast China was driven by mean annual precipitation (15.3% explained) and hydrogen (10.8%). In contrast, in Xinjiang, it was driven by phosphorus (17.8%), sulfur (14%), and chromium (12.4%). Soil water content, titanium, and mean monthly precipitation were key regulators of bdelloid rotifer communities in both regions. These findings suggest that climatic conditions and soil physicochemical factors play a pivotal role in shaping the community structure of bdelloid rotifers in soils across diverse geographic regions.

The excessive application of nitrogen fertilizers in agriculture increases emission of nitrous oxide (N₂O), a greenhouse gas, while the issue of low nitrogen use efficiency remains unresolved. Based on a chamber incubation experiment under constant temperature and humidity conditions, we investigated the effects of combined application of nitrification inhibitors (DCD) and denitrification inhibitors (an  acid-ester compound, referred to as PCB) on soil N₂O emission. There were four treatments: urea alone, urea+DCD, urea+PCB, and urea+DCD+PCB. The results showed that treatments with nitrification inhibitors alone and denitrification inhibitors alone reduced cumulative N₂O emission by 13.4% and 12.3%, respectively, by decreasing the AOB amoA and nirK genes, respectively. The addition of urea+DCD reduced the abundance of the AOB amoA gene by 16.7% and 22.7% on day 1 and 7 of cultivation, respectively. The addition of urea+PCB reduced the abundance of the nirK gene by 23.3% and 16.5% on day 7 and 35 of cultivation, respectively. However, the combined application of nitrification and denitrification inhibitors synergistically regulated soil nitrogen transformation by inhibiting both nitrification and denitrification, in that it reduced soil nitrification potential, soil nitrate reductase activity, the abundance of AOB amoA genes by 11.0%-29.4% and nirK genes by 8.0%-38.8%, resulting in a 19.7% reduction of N₂O emissions. Our results provide theoretical support and technical guidance for reducing greenhouse gas emissions in agriculture.

Soil improvement in the open-pit mine dumps of grasslands plays an important role in the restoration of degraded grasslands. To explore the role of soil improvement in vegetation restoration, we examined the effects of two soil amendment pathways, humic acid (30 t·hm^-2) and vermicompost (30 t·hm^-2) addition, on soil and vegetation in the open-pit mine dumps of a grassland in eastern Inner Mongolia. The results showed that single applications of humic acid and vermicompost could significantly promote plant growth. The combined application of the two showed a significant interactive effect, with a 3.67-fold increase in biomass compared with the control. Humic acid effectively reduced soil pH (by 1.08) and increased soil organic carbon content (by 8.5 times), while vermicompost significantly increased the content of total phosphorus (by 77%), alkaline nitrogen (by 1.5 times), available phosphorus (by 2.4 times), and available potassium (by 50%) in the soil. The dominant bacterial phyla were Actinobacteria and Proteobacteria, while the dominant fungal phyla were Ascomycota and Basidiomycota in open-pit mine dump soil. Soil amendments significantly increased the bacterial Shannon index and enhanced ecosystem stability. Plant biomass was significantly positively correlated with soil nitrogen content. This study proposes a synergistic improvement technology of humic acid and vermicompost, which synchronously regulates soil physicochemical properties and microbial community structure, providing an efficient solution for ecological restoration in grassland mining areas, and having promotional value for the restoration of similar fragile ecosystems.

Changes in vegetation types regulate regional land surface temperature through biophysical processes. In this study, the Weather Research and Forecasting (WRF) mesoscale model was used to simulate conditions across Northeast China in 2018. Two numerical experiments were designed, including one simulation (2018_ctr) retaining all original land surface types over the study domain and another (2018_grass) where all forests within the domain were converted to grassland. We quantified the disparities in albedo, leaf area index (LAI), shortwave and longwave radiation, and diverse surface heat fluxes between forest and grassland grids to explore the biophysical effects of afforestation and their impacts on land surface temperature. The WRF outputs were validated against interpolated ERA reanalysis data, and the model well reproduced the spatial pattern of land surface temperature with a correlation coefficient of 0.9258. The simulated temperature exhibits an overall warm but acceptable bias, confirming the model’s applicability for regional analysis. The results showed that afforestation markedly increases LAI and reduces winter surface albedo, which further modulates land surface temperature. In the vegetation replacement zones of northern Northeast China, land surface temperature of forest grids exceeds that of converted grassland grids by more than 0.8 K in winter daytime, with a nocturnal warming magnitude of 1 K. During summer daytime, forest surfaces in these zones are over 0.8 K cooler than grassland surfaces, areas without vegetation conversion undergo a 0.8 K warming, and forest surfaces stay 0.4 K warmer than grassland surfaces at night. Spring and autumn follow similar diurnal patterns, featuring warming in the northeastern part and cooling in the southeastern part of the study region. Diagnoses of surface energy balance combined with the Decomposition of Temperature Metric (DTM) reveal that daytime warming is primarily driven by enhanced absorption of surface shortwave radiation, while sensible heat flux mitigates such warming. Daytime cooling induced by afforestation arises from both radiative and nonradiative pathways. Reduced shortwave radiation absorption dominates cooling in summer and autumn, while strengthened sensible and latent heat release from forests to the atmosphere in winter and spring accelerates surface heat loss and generates nonradiative cooling. Nocturnal warming from spring to autumn is predominantly controlled by longwave radiation, with the most pronounced signal in summer, and soil heat flux exerts a substantial warming effect on land surfaces in winter.

Under the scenarios of climate change and intensified grazing activities, exploring the response characteristics of grasslands to extreme climate in different grazing intensity areas of Inner Mongolia is of great significance for the coordinated development of pastoral economy and healthy ecological environment. Based on net primary productivity (NPP) and meteorological data from 2001 to 2023, we integrated trend analysis, linear correlation analysis, the XGBoost + SHAP framework, and the Hurst index to examine the responses of grassland NPP to climate extremes across different grazing intensity zones in Inner Mongolia. The results showed that: (1) NPP increased significantly at a rate of 3.09 g C·m^-2·a^-1, with the highest increase in heavy grazing zones (4.44 g C·m^-2·a^-1), followed by moderate (3.21 g C·m^-2·a^-1) and light (1.94 g C·m^-2·a^-1) grazing zones. (2) Inner Mongolia grasslands experienced an overall warming and drying trend. Pronounced warming and drying were observed in the light and moderate grazing zones located the southwestern Inner Mongolia, while the heavy grazing zone in the northeastern Inner Mongolia showed a warming and wetting trend. (3) NPP was more sensitive to extreme precipitation than extreme temperature. Extreme precipitation generally had a positive effect on NPP across different grazing intensity zones, without spatial variations. Specifically, the decrease of extreme precipitation inhibited NPP in light and moderate grazing zones, whereas the increase of extreme precipitation promoted NPP in heavy grazing zones. Extreme temperature generally exerted a negative influence on NPP, and the magnitude of this effect increased with grazing intensity. The overall warming across the study region tended to suppress the growth of NPP. (4) Grassland NPP in light and moderate grazing zones may continue to be negatively affected by extreme high temperature and precipitation events. In contrast, future climate conditions in the heavy grazing zone, characterized by a reduction in the extreme low and high temperatures as well as an increase in precipitation events, are likely to enhance grassland NPP. Our findings provide scientific support for pastoral grassland ecological restoration, rational grazing management, and the mitigation of extreme climate impacts.

With the continuous research progress in plant acoustics, the capability of plants to perceive acoustic waves and their potential applications in green agriculture have been extensively demonstrated. The cross-scale regulatory mechanisms of acoustic wave-mediated plant growth and development have not yet been systematically elucidated. We summarized the research progress on the effects of both audible sound and ultrasound on plants. From the perspective of the entire life cycle, i.e., encompassing seed germination, vegetative growth, and reproductive growth, we outline the stage-specific response characteristics of plants to acoustic stimulation. On this basis, we delve into the underlying physiological and molecular mechanisms by which acoustic waves induce phenotypic changes, focusing on three core levels: metabolic networks, gene transcription, and intracellular signal transduction. Furthermore, we evaluated the application status of acoustic frequency technology in fields such as crop yield enhancement, abiotic stress tolerance improvement, postharvest quality regulation, and non-destructive testing. Existing evidence indicates that acoustic waves, functioning as non-chemical physical elicitors, can effectively enhance crop physiological performance and reduce reliance on chemical inputs, representing a highly promising direction in physical agriculture. Addressing current bottlenecks such as unidentified perception receptors and the difficulty in standardizing field parameters, future research should focus on utilizing multi-omics technologies to decipher core response pathways and promoting interdisciplinary integration to develop intelligent acoustic equipment. Such efforts will lay a foundation for refining the theoretical framework of plant acoustics and facilitating its large-scale application in smart agriculture.

Although the status of ecological protection continues to improve in China, ecological destruction incidents occur sporadically due to predatory development, resource externalities, and chaotic natural resource management. A clear, unified definition and classification of ecological destruction is unavailable, and thus there are many difficulties for management in both theoretical analysis and practical application. We analyzed the conceptual connotation and typical cases of ecological destruction, and summarized the main types and causes. Future research should consider ecosystem integrity, the internal relationships among the components, as well as the consequences of destructive behaviors. Long-term regulatory governance systems should be strengthened through improving regulations and standards, enhancing problem identification capabilities, strengthening supervision and law enforcement, and leveraging social supervision, to provide theoretical, methodological, and practical guidance for the prevention and control of ecological destruction.

Based on UAV multispectral imageries combined with field-measured samples from typical no-till reseeded grasslands in alpine regions, four models, including multiple linear regression (MLR), ElasticNet, random forest (RF), and support vector regression (SVR), were developed to compare the performance of aboveground biomass (AGB) estimation under different model types (linear and nonlinear models) and data organization strategies (classification modeling by grassland type, overall sample modeling, and overall sample modeling with grassland-type dummy variables). The results showed that sample heterogeneity was evident among different grassland types, and that the relationship between fractional vegetation cover (FVC) and AGB varied with grassland type. In the classification modeling, there was no single optimal model for all grassland types. For each grassland type, ElasticNet performed best for alpine meadow grassland (test R²=0.808), whereas MLR was optimal for alpine desert grassland (R²=0.728). The performance of all models was generally poor for alpine grassland (R₂<0.40). For the overall sample modeling, the test R² values of all models ranged from 0.519 to 0.573. Although SVR showed better performance (R²=0.573), the overall results were inferior to those of classification modeling. The performance of all models did not improve after introducing dummy variables for grassland type. Under the classification modeling strategy, linear models were generally more stable than nonlinear ones. In contrast, under the overall sample modeling strategy, the performance gap between the two types of models narrowed, with SVR showing a relative advantage. Variable contribution analysis indicated that the Normalized Difference Vegetation Index (NDVI), Green Normalized Difference Vegetation Index (GNDVI), and FVC were the main explanatory variables for AGB estimation in the overall sample set, though key variables differed among grassland types. These findings demonstrate that sample heterogeneity and data organization strategy are key factors affecting the accuracy of AGB estimation for no-till reseeded grasslands in alpine regions. The classification modeling is more targeted and stable than overall modeling and dummy-variable treatment.