Tree allometric models based on height (H) and diameter (D) are the most commonly used method to estimate forest biomass. Environments and stand characteristics are recognized to affect tree allometries. However, few studies have considered to incorporate these effects into allometric models, which restricts the use of these models in a wide domain. Adopting the power-law function Y = aG^b as a basic model where Y is either tree height or biomass and the corresponding G is tree diameter D at breast height or D²H, we developed a two-step approximation procedure to quantify the effects of environments and stand characteristics on allometric coeffcients a and b for Cunninghamia lanceolata and Pinus forest in China. Results show that most of the allometric coeffcients are dependent on stand characteristics for C. lanceolata forest, and on mean annual temperature, stand age and latitude for Pinus forest. The allometric models via the two-step approximation Y = f(α + α_jx_j) G^{f (β+βixi)} (x_j or x_i are key drivers associated with environments and stand characteristics. α, α_j,β and β_i are regression coeffcients) considerably improved the accuracy of tree height and biomass estimation. Compared to the basic model, the second approximation models signifcantly reduced the mean absolute bias between the observed and computed values by 25%–34% for C. lanceolata and by 21%–26% for Pinus forest, respectively. Our results highlight the necessity of incorporating environments and stand characteristics into the allometric models and provide a universal method to accurately estimate H-D-based tree biomass across a wider domain.

The decomposition of deadwood is a crucial process for the accumulation and sequestration of soil organic carbon (SOC) in forest ecosystems. However, the response of SOC to different decay classes of deadwood and the underlying mechanisms remain poorly understood. Here, we investigated the dynamics of SOC, soil properties, extracellular enzyme activities, and phospholipid fatty acid biomarkers across five decay classes (ranging from 1 to 5) of Masson pine (Pinus massoniana Lamb.) downed deadwood in a subtropical–temperate ecotone forest in Central China. Our results revealed a nonlinear response pattern of SOC along the deadwood decomposition gradient, with the maximum value at the decay class 4. Soil available nitrogen content, bacterial biomass, fungal biomass, the ratio of fungal-to-bacterial biomass, cellulase, activity and ligninase activity all increased with the intensification of deadwood decay, while soil pH decreased. The increase in SOC content was associated with a direct positive effect of bacteria and both direct and indirect positive effects of fungi by cellulose activity, but ligninase activity showed no significant relationship with SOC content. These findings suggest that cellulose and microbial biomass are key determinants of soil C formation and sequestration during deadwood decomposition. This study highlights the importance of the nonlinear response of SOC to deadwood decay, providing valuable insights for predicting future carbon-climate feedbacks.

Understanding the driving mechanisms of forest changes is of great significance for developing effective adaptation strategies to mitigate the impacts of climate change and human activities on ecosystems. This study used Theil–Sen median trend analysis, Mann–Kendall test, contribution rate decomposition, partial least squares, geodetector and residual analysis to explore the impact of climate change and human activities on the forest coverage area and NDVI of the Altai Mountains. Results show that changes in forest cover are driven by both forest management policies and climate change. Among them, forest management policy is the main factor. However, there are differences in the driving mechanisms in different altitude zones: in the alpine and subalpine zones, the promoting effects of natural death and climate change bring the forest coverage area toward a dynamic balance, while under the combined effects of human activities and climate change, the forest coverage area in the low mountain zones shows an expansion trend. For forest NDVI, the analysis results of the six scenarios show that the joint action of climate change and human activities promotes the growth of forest NDVI in the largest proportion (50.20%); the impact of climate change on forest NDVI is greater than that of human activities, and most of it is a promotion effect (30.28%). Forest degradation is mainly caused by human activities (19.39%), especially in the edge areas of the forest. Among climate factors, precipitation and snowmelt water are the main controlling factors for forest growth. Snowmelt water from March to April is an important water source before the growing season. This study provides the important scientific basis for forest management and strategic planning in the Altai Mountains.

Phenological models are valuable tools for predicting vegetation phenology and investigating the relationships between vegetation dynamics and climate. However, compared to temperate and boreal ecosystems, phenological modeling in alpine regions has received limited attention. In this study, we developed a semi-mechanistic phenological model, the Alpine Growing Season Index (AGSI), which incorporates the differential impacts of daily maximum and minimum air temperatures, as well as the constraints of precipitation and photoperiod, to predict foliar phenology in alpine grasslands on the Qinghai–Tibetan Plateau (QTP). The AGSI model is driven by daily minimum temperature (T_min), daily maximum temperature (T_max), precipitation averaged over the previous month (PA), and daily photoperiod (Photo). Based on the AGSI model, we further assessed the impacts of T_min, T_max, PA, and Photo on modeling accuracy, and identified the predominant climatic controls over foliar phenology across the entire QTP. Results showed that the AGSI model had higher accuracy than other GSI models. The total root mean square error (RMSE) of predicted leaf onset and offset dates, when evaluated using ground observations, was 12.9 ± 5.7 days, representing a reduction of 10.9%–54.1% compared to other models. The inclusion of T_max and PA in the AGSI model improved the total modeling accuracy of leaf onset and offset dates by 20.2%. Overall, PA and T_min showed more critical and extensive constraints on foliar phenology in alpine grasslands. The limiting effect of T_max was also considerable, particularly during July–November. This study provides a simple and effective tool for predicting foliar phenology in alpine grasslands and evaluating the climatic effects on vegetation phenological development in alpine regions.

This study used a method based on a spatial series in place of a temporal series, selecting Tamarix ramosissima shrubs at different developmental stages of coppice dunes as research subjects to investigate their chlorophyll fluorescence characteristics and non-structural carbohydrates (NSC). The results indicated that: (1) As coppice dunes developed, T. ramosissima showed a significant increase in photosynthetic pigment content alongside a decrease in actual photochemical efficiency (Y_(II)). Simultaneously, the reduction state of the plastoquinone (PQ) pool intensified, the apparent electron transport rate (ETR) increased, and the quantum yield of regulated energy dissipation significantly increased. These adaptations enabled T. ramosissima to dissipate excess light energy by enhancing its non-photochemical energy dissipation mechanisms. (2) Photosynthetically active radiation (PAR) and T. ramosissima leaf temperature (T_L) gradually increased during coppice dune development, whereas soil water content decreased, leading to increased stress on T. ramosissima and a subsequent decline in NSC content. This increased stress placed T. ramosissima at risk of ‘carbon starvation’, resulting in a gradual reduction in photosynthesis, biomass accumulation, and ultimately, mortality. (3) Correlations among various indicators of T. ramosissima were significant, with the highest degree of association and marked enhancement of synergistic effects in the growth and stable stages of coppice dunes. Comprehensive analysis revealed that high soil moisture content can alleviate water stress, improve light energy use efficiency and enhance the photosynthetic carbon assimilation process in T. ramosissima during coppice dune development.

Leaf construction cost (LCC), a proxy for the energetic investment plants make to construct leaf biomass, indicates carbon investment strategies of plants across diverse habitats. However, large-scale variations in LCC and their correlations with climate and soil factors have yet been fully explored. To address this knowledge gap, here, we compiled a dataset comprising 442 species-site combinations, spanning nearly all vegetation types in China. We found that LCC exhibited substantial variation, ranging from 0.72 g glucose g⁻¹ to 1.93 g glucose g⁻¹, with an average of 1.25 g glucose g⁻¹. LCC was significantly higher in woody species compared to nonwoody species; however, there was no significant difference in LCC between evergreen and deciduous plants. LCC decreased with increasing latitude and longitude but increased with increasing altitude. Among bivariate LCC-environment relationships, LCC was positively correlated with mean annual precipitation and temperature but negatively correlated with temperature seasonality, precipitation seasonality, soil potassium content, and soil silt content. Collectively, climate and soil factors account for over 54% of the variance in LCC, with soil exerting a more significant influence than climate on LCC. This study offers an exhaustive analysis of the evident pattern of LCC over a large spatial scale, fostering a fresh perspective on functional biogeography and establishing the foundation for exploring the interplay between LCC, ecological functions, and macroevolutionary implications.

Soil microbes play a critical role in maintaining the health and stability of these ecosystems. However, the ecological assembly processes of soil microbial communities remain poorly understood. This study explores the changes in ecological components across original and degraded patches of alpine meadows in Sanjiangyuan National Park and analyzed soil microbial community structure using high-throughput sequencing techniques. Results showed that alpine meadows degradation increased vegetation species diversity, significantly reduced aboveground productivity, and made the soil more barren and alkaline. Although the dominant phyla of soil microorganisms were similar across different degradation states, degradation significantly increased the relative abundance of oligotrophic bacteria and decreased the relative abundance of dominant fungi. Additionally, microbial communities exhibited significant β-diversity. Degradation also led to an increase in microbial α-diversity, heightened microbial taxa competition and a more complex microbial co-occurrence network. However, vegetation-soil variables explained only a small portion of the variation in soil microbes. Through the study of microbial ecological assembly processes, we found that degradation enhanced the stochastic processes of soil microbial communities, and the changes in soil microbial communities were mainly driven by the variations inherent in the microbes themselves. These findings highlight the complex ecological interactions between above- and belowground components and emphasize the critical role of microbial community dynamics in mediating ecosystem functions.

The invasion of Spartina alterniflora (SA) has led to significant hydrogen sulfide (H₂S) production in coastal wetlands. The phytotoxic S²⁻ plays a critical role in elemental biogeochemistry and may contribute to the successful invasion of SA in areas contaminated with heavy metals. To explore how H₂S influences nutrient uptake and energy utilization in SA and the native Phragmites australis (PA) under cadmium (Cd) stress, and to uncover the mechanisms by which H₂S facilitates SA invasion, a hydroponic experiment was conducted. This experiment included three Cd concentrations (0, 1 and 2 mg Cd L⁻¹) and three H₂S treatments (inhibiting H₂S synthesis, simulating an external H₂S source and untreated control). Results revealed that H₂S plays a crucial role in balancing the uptake of Mg, Mn, Ca and Zn in SA, mitigating Cd-induced damage to the photosynthetic system and enhancing nutrient and energy accumulation under Cd stress. In contrast, H₂S was toxic to PA, increasing lipid peroxidation, inhibiting growth, and disrupting mineral uptake, particularly of Ca. This exacerbated the detrimental effects of Cd on the photosynthetic system and nutrient accumulation in PA. These results highlight that irrespective of Cd treatment, H₂S enhanced energy accumulation, mineral uptake, and growth in SA compared to PA, which could support the ecological niche competition within the coastal wetlands during the invasion of SA into PA habitats. Consequently, inhibiting endogenous H₂S synthesis in SA may offer a potential strategy for controlling its invasion.

Floodplain wetlands have a signifcant capacity for carbon sequestration but are vulnerable to land use changes. Poplars are extensively planted in wetlands due to the increasing demand for wood products and bioenergy. Although the large biomass of poplar may increase the carbon stock in wetlands, their high transpiration rates may reduce soil moisture, thereby improving the aeration and facilitating the oxidation of organic materials. Therefore, the impact of poplars on wetland carbon stock remains uncertain and unexplored. Here, we investigated the effects of poplar plantations on biomass carbon stock (BCS) and soil organic carbon (SOC) stock in Dongting Lake wetlands, China, using native Miscanthus lutarioriparius vegetation as a control. Our results indicated that the BCS of middle-aged and near-mature poplar plantations (36.47–81.34 t ha⁻¹) was higher than that of M. lutarioriparius (8.31 t ha⁻¹), and it increased with stand age. The SOC stock within the 0–60 cm depth in young, middle-aged, and near-mature poplar plantations (130.32–152.58 t ha⁻¹) were higher than those in M. lutarioriparius (70.48 t ha⁻¹), but they did not increase with stand age. The BCS was positively associated with soil bulk density, while SOC stock was negatively associated with soil sand content. Overall, our fndings indicate that poplar plantations increase carbon stock in the Dongting Lake wetlands. Nevertheless, the longterm effect of poplar plantation on carbon sequestration in foodplain wetlands should be further investigated.

Plant root-associated fungal communities play a pivotal role in enhancing plant growth, nutrient absorption, disease resistance and environmental stress adaptation. Despite their importance, the assembly processes of these communities remain inadequately explored. In this study, we utilizzzed high-throughput sequencing, co-occurrence network analysis and null models to examine the diversity, composition, interaction patterns and assembly mechanisms of the root-associated fungal communities of Mussaenda pubescens, a drought-tolerant shrub that thrives in stressful environments and is widely used for Chinese medicine. Our findings revealed pronounced regional and ecological niche-based variations in the diversity and assembly of total fungi and essential functional guilds, including saprotrophs, symbiotrophs and plant pathogens. Significantly, the fungal diversity of plant pathogens decreased with elevation, whereas total fungi, saprotrophs and symbiotrophs were minimally affected. Stochastic processes, such as dispersal limitation, played a significant role in fungal assembly. Furthermore, soil physicochemical properties, climatic conditions and spatial variables emerged as critical determinants of fungal community structure. This study enriches our understanding of the dynamics governing root-associated fungal community assemblies and underscores the factors essential for sustaining fungal diversity.

Fruit type influences seed dispersal mode and its effectiveness, reflecting plant adaptability to their environments. However, the large-scale patterns of fruit type distribution in forest communities and differences in the drivers of various fruit types remain unclear. We present a large-scale biogeographic model of woody plant fruit types along a latitudinal gradient through the data analysis of 30 forest dynamic plots. Results showed the following: (1) Fleshy and dry fruits exhibited distinct distribution patterns in large-scale space. The distribution of fleshy fruits was greater in tropical and subtropical zones, while dry fruits were more common in temperate zones. (2) Climatic factors primarily drove the geographical distribution of the fruit types of woody plants. Climatic and spatial factors exerted greater effects on the species richness of dry fruits compared with that of fleshy fruits. These results demonstrated the difference in the latitudinal gradient patterns of fleshy and dry fruits and identified the major abiotic environmental factors that drove their large-scale distribution, demonstrating the biogeography of the fruit types of woody plants.

Interactions among roots and leaves are fundamental for plant growth and survival, yet there remains a knowledge gap in mangrove plants that experience saline stress distinct from most other vascular plants hereafter the non-mangroves. Here, we explored the coordination of above- and below-ground trait relationships among mangrove species in tropical China and compared it with those of non-mangroves. Our results show that root stele, the water-conducting tissue, was coupled with leaf water use traits and tissues outside the stele (ToS), the carbon-consuming tissues in roots, were independent of leaf economics traits in non-mangroves. However, in mangroves, root stele is independent of leaf water use traits and root ToS is coupled with leaf economics traits. The contrasting root–leaf coordination between mangroves and non-mangroves potentially arises from the existence of leaf water storage tissues in mangroves and the universal allometric relationship between root stele and ToS in both plant groups. Our findings pave a new way for understanding the ecology and vegetation dynamics of mangrove and non-mangrove plants under global environmental change.

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) monoculture plantations account for 17.4% of the total plantation area in China. The decomposition of Chinese fir litter plays a fundamental role in maintaining nutrient cycling and soil fertility in these plantations. Here, we conducted a continental synthesis based on 64 studies to estimate the mass loss and release rates of carbon (C) and nutrients (including nitrogen (N), phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg)) during the first year of Chinese fir litter decomposition. The average mass loss rates of needle, twig, root and cone litter were 0.503, 0.319, 0.551 and 0.372 year^-1, respectively. The decomposition rates of C and cellulose for needle litter were 0.649 and 0.801 year^-1, respectively, while those of K, Ca and Mg were 2.27, 0.852 and 0.551 year^-1, respectively. Decomposition rates were strongly influenced by mean annual temperature, soil N concentration and the initial C/N ratio of the litter. Climate warming and elevated ultraviolet-B radiation accelerated mass loss of Chinese fir litter, while increased N deposition and acid rain reduced it. However, elevated N deposition facilitated nutrient release from decomposing Chinese fir litter. These results provided a comprehensive assessment of Chinese fir litter decomposition, which is crucial for understanding soil biogeochemical cycles and improving soil fertility in Chinese fir plantations under global change scenarios.

Traits and their correlation networks can reflect plant adaptive strategies. However, variations in traits and trait correlation networks across heteromorphic leaves within species remain largely unexplored. In this study, we systematically quantified a diverse array of leaf traits—spanning morphology, anatomy, physiology and biochemistry—among the striped, lanceolate, ovate, and broadly ovate leaves of Populus euphratica, aiming to elucidate the adaptive differences across these various leaf types. We found that the four heteromorphic leaves showed significant differences in leaf traits. From striped leaves to broadly ovate leaves, leaf size, leaf thickness, water use efficiency and catalase content significantly increased, while specific leaf area showed the opposite pattern. Principal component analysis and cluster analysis revealed distinct aggregation and clear demarcation of the four leaf types, indicating substantial variations in trait compositions and their distinct ecological adaptations. Plant trait networks varied significantly across the four leaf types, with the broadly ovate leaves exhibiting a fragmented network structure that enhances their modularity. This suggests strong resilience to disturbances and is consistent with the characteristic foliage on mature trees. Regardless of leaf type, nitrogen and phosphorus consistently emerged as hub traits within plant trait networks, underscoring their fundamental role in driving physiological processes and influencing phenotypic expression. This study meticulously delineates the variations in both individual leaf traits and trait correlation networks across the heteromorphic leaves of P. euphratica, significantly deepening our understanding of plant adaptive strategies.

Canopy properties (e.g. canopy structure and spectral variables) strongly influence forest above-ground biomass (AGB). However, the importance of these canopy properties in driving AGB in natural forests, especially relative to other drivers such as plant species diversity and environmental conditions, remains poorly understood. We assessed the relative importance of canopy properties (structure and spectral variables) and plant species diversity (multidimensional diversity metrics and trait composition) in regulating AGB along environmental gradients (topography and soil nutrients) in a temperate forest in Northeast China, using UAV-based LiDAR and hyperspectral data. We found that the explanatory power of environmental conditions, plant species diversity, canopy spectral properties and canopy structure on temperate old-growth forests AGB was 3.8%, 8.0%, 4.1% and 13.3%, respectively. AGB increased with increasing canopy height and structural complexity. Canopy spectral diversity was a better predictor of AGB than traditional diversity metrics in old-growth forests. Canopy spectral composition also played an important role in explaining AGB in the secondary forests. In addition, plant phylogeny, functional diversity and the community-weighted mean of acquisitive traits had significant direct positive effects on AGB. Finally, topography and soil nutrient content indirectly influenced AGB through canopy properties and plant species diversity. Our study highlights the key role of canopy properties in influencing AGB. For future monitoring, regular monitoring with spectral and LiDAR data should be emphasized to provide real-time insights for forest management.

Bidens pilosa, a globally invasive Asteraceae plant, threatens both natural and agro-ecological habitats. Species distribution models (SDMs) are a valuable tool for predicting invasion potential, often exclusively based on climate variables. Here, we aimed to predict the current and future global distribution of B. pilosa by integrating climatic, human-induced and biodiversity factors, all of which are critical for accurate projections. Our more comprehensive results showed that climate conditions were the main driver of B. pilosa’s current distribution, with an expanded suitable area compared to previous studies, especially in eastern China and the Sichuan Basin. Incorporating human-induced factors significantly reduced predicted suitable areas, reflecting the species’ association with disturbed environments shaped by human activities. Biodiversity factors further refined habitat suitability, as areas with high phylogenetic richness were identified as potential hotspots for invasion due to competitive or facilitative interactions. Future predictions, based on solely available climate data, suggested a high risk of habitat expansions in Asia, Europe and North America. Niche dynamic analyses revealed that introduced populations occupied a distinct environmental niche space compared to native populations, due to adapting to altered climatic and anthropogenic conditions. This ecological niche divergence is likely driving the increased invasion risk in the introduced range. Our study underscores the complex interactions between climate conditions, biodiversity and human activity in shaping the spread of B. pilosa. SDMs integrating climatic, biotic variables and human-influenced factors, together with updated occurrence data improve predictions of invasion spread and help guide targeted management.

Invasive plants alter soil microbial communities and physicochemical properties through chemical inputs from litter, root exudates and leachate, impacting a range of soil processes, but precise effects are poorly understood. We investigated the little effects of Solidago canadensis, a common invasive species in China, on soil microbial communities under natural conditions. Experimental treatments included S. canadensis seedling density (1 and 2 plants/pot) and litter quantity (10 and 20 g/pot), with control groups containing no plants or litter. After 120 days, soil samples were analyzed for physico-chemical properties, GC–MS chemical composition, and bacterial community composition using high-throughput sequencing. Results showed that S. canadensis seedlings and litter inputs significantly increased soil pH, soil organic matter (SOM), and total nitrogen (TN), while phosphorus and potassium remained unchanged. We identified 66 chemical compounds, predominantly ketones, alcohol, aldehyde, hydrocarbon, ester, acid, terpenoids and alkaloids, associated with the presence of S. canadensis, alongside shifts in dominant bacterial genera including Sphingomonas, Acidobacteriales and Gemmatimonas. Rarer genera under the invasive treatment species, such as Candidatus, Rhodoplanes and Novosphingobium, were positively correlated with soil TN, pH, and SOM. Collectively, these findings demonstrate that allelochemical inputs from S. canadensis litter and root exudates significantly reshape soil properties and microbial communities, with potential implications for ecosystem dynamics and invasion success.

Elevational gradients provide a unique opportunity to explore the plasticity of plant-pollinator interactions, which is crucial for understanding ecological and evolutionary processes in plant pollination systems. Species-specific dispersal across elevation gradients of tropical mountains is constrained by the different tolerance of individual species to abiotic factors. Consequently, the composition of plant and pollinator communities, such as their interactions, changes continuously. For example, previous studies have shown a bee-to-fly transition as elevation increases, or that at high elevations, bird-pollinated plants may be more effectively pollinated than closely related bee-pollinated species, highlighting an altitude-driven bee-to-bird transition. We used Hypericum revolutum (Hypericaceae) as a model plant, to explore how the identity and activity of floral visitors change along an elevational gradient in the montane grasslands of Mount Cameroon. We observed flower visitors across four elevations during two seasons. Our study confirmed the predicted bee-to-fly transition with increasing elevation. Bird activity followed a hump-shaped pattern, peaking around 2800 meters above sea level. Male Cinnyris reichenowi individuals, the main bird floral visitor, exhibited higher activity than females throughout the entire elevational gradient and across both study periods. The observed patterns suggest that plants may face evolutionary pressures to adapt to these shifting pollinator communities, potentially driving local adaptations and diversification within populations.

Phenology is one of the most reliable tools for understanding the effect of climate change on forests. Although there has been increasing research into the effect of climate on phenological activity, little is known about how phenological patterns for the same species may vary among environments, particularly for tropical species. Here we analyzed the reproductive phenology of an important tropical rainforest tree species in northeastern Australia, Cardwellia sublimis, and compared the patterns among five different sites. We also tested and compared the climate drivers of reproductive phenological activity among sites for this species. Degree of seasonality varied across sites with most sites presenting moderate to high seasonality. Flowering and fruiting peaked in different seasons at the different sites and we found flowering and fruiting phenology were often influenced by different climate drivers at the different sites. Where the climate drivers were the same, the magnitude and direction of the effect of the drivers differed among sites. Precipitation was the most common climate driver of flowering, being significant for all sites, while fruiting was predominantly influenced by temperature and solar radiation. Finally, we found evidence that relationships between climate drivers and phenological patterns were dependent on inter-site differences in climate and geography. Our results demonstrate that species may present varied phenological patterns and varied responses to climate drivers depending on environmental conditions and site location. These results have important implications for modelling phenological patterns based on limited field information, as well as for understanding species vulnerability to climate change.

Isolated individual processes of ecosystem carbon (C) cycles have largely shaped our understanding of C cycle processes under environmental change. Yet, in reality, C cycle processes are inter-related and hierarchical. How these processes respond to warming and grazing has rarely been investigated in a single manipulative experiment. Moreover, biodiversity loss is a major driver of ecosystem change under environmental change, but whether these responses are mechanistically linked to biodiversity remains unclear. Here, we performed a 5-year field manipulative warming with seasonal grazing experiment in an alpine meadow on the Qinghai-Tibetan Plateau. Our results showed that both warming and moderate grazing decreased net ecosystem productivity (NEP) by 42.1% and 38.3%, and their interaction decreased it by 56.2% during the summer grazing period. However, they had no significant effects on NEP during the winter grazing period. Overall, annual gross primary productivity (GPP) and ecosystem respiration (Re) were mainly determined by aboveground rather than belowground processes, and Re variation, which was mainly controlled by aboveground respiration explained 50% of the variation in annual NEP under warming and grazing. Moreover, lower species richness induced by warming and grazing caused smaller NEP with smaller net primary productivity and higher aboveground respiration. The responses of aboveground C cycle processes were greater than that of belowground C cycle processes, suggesting asymmetric above- and belowground responses to warming and grazing. Therefore, our findings suggested that there were higher GPP and Re with lower C sequestration (‘two high with one low patterns’) under warming and moderate grazing. Plant diversity modulated the responses of soil C sequestration to warming and grazing. It is essential to understand the underlying mechanisms of the effects of biodiversity on hierarchical C cycle processes under combined warming and grazing in the future.

The carbon balance processes of plants in response to diurnal environmental changes are critical for their growth and survival. While sex-specific responses in photosynthesis to environmental stress have been observed in several dioecious plant species, the diurnal dynamics of carbon balance in male and female individuals remain unexplored. Here, we investigated the diurnal variations of photosynthetic rate (A), dark respiration rate (R_d), A/R_d, and the concentration, pool, and allocation of nonstructural carbohydrates (NSC) of male and female mulberry (Morus alba) seedlings. Males exhibited the highest A at 09:00, while females had the highest A and R_d at 13:00. Male A was higher than female A at 09:00, whereas male R_d was lower than female R_d at 13:00. The A/R_d was higher in males than in females. The peak of NSC concentration in males was earlier than in females, and the NSC concentration and storage in the whole plant, leaves and bark were generally higher in males than in females across most time points. The average NSC allocation followed the leaves > roots > bark ≈ trunk trend, but its dynamic changes over the daily cycle were more pronounced in females than in males. These findings suggest that carbon balance processes in mulberry seedlings exhibit sex-specific responses to diurnal changes, with females displaying greater sensitivity to these variations. This study provides the first attempt to explore such responses in woody plants and suggests that future carbon cycle models for terrestrial plants should incorporate plant sex.

The stability mechanisms of ecosystem functions have been a hot topic in ecology. However, in wetland ecosystems, the mechanisms by which biotic and abiotic factors interact to affect ecosystem stability in changing environments remain largely unclear. This study investigated the key factors and underlying mechanisms that regulate the spatial variability of wetland productivity by measuring community productivity, multiple components of biodiversity (i.e. species diversity, community functional composition and diversity) and environmental factors along a well-characterized gradient of wetland degradation in the lower reaches of the Yellow River. The results showed that the spatial variability of productivity in wetlands increased with intensified degradation. The spatial variability of wetland productivity was not related to species richness but was mainly affected by changes in community functional composition and diversity. Furthermore, degradation-induced changes in soil nutrients drove the spatial variability of productivity to increase with shifts in functional composition towards more conservative traits (i.e. higher leaf dry matter content and root tissue density), and to decrease with higher functional trait diversity. These findings reveal the driving mechanism of spatial variability in wetland productivity under degradation, and suggest that reduced nutrient availability, by altering plant resource strategies, can affect the spatial reliability of key ecosystem functions in wetlands.