Aims Soil nitrogen mineralization,nitrification and microbial nitrogen immobilization are key processes in soil nitrogen cycle,which have an important impact on soil nitrogen supply.Exploring the spatial variations in soil nitrogen transformation rates of forest may contribute to in-depth understanding of forest soil nitrogen dynamics and forest ecosystem productivity. Methods In this study,we integrated and analyzed 685 observations from 78 published papers,and aimed to analyze the rate characteristics of soil gross nitrogen mineralization,gross nitrification and microbial nitrogen immobilization of forest ecosystem and the main influencing factors. Important findings The results showed that:(1)The average rate of soil gross nitrogen mineralization,gross nitrification and microbial nitrogen immobilization of forest ecosystem were(6.65±0.61),(1.99±0.21)and(8.10±1.45)mg N·kg-1·d-1,respectively.(2)The soil gross nitrogen mineralization rate and gross nitrification rate differed significantly among various forest types.Higher gross nitrogen mineralization rates were observed in tropical forest and temperate coniferous forest,while lower rates in subtropical broad-leaved forest and subtropical coniferous forest.The microbial nitrogen immobilization rates were higher in temperate coniferous and broad-leaved mixed forest,but was lower in subtropical coniferous and broad-leaved forest.(3)Soil gross nitrification rates exhibited no significant differences among various forest types.(4)The spatial variations in soil gross nitrogen transformation rates were main regulated by soil total nitrogen content and microbial biomass.Overall,the gross nitrogen transformation rates exhibited large spatial variability across global forest,and they were mainly affected by substrate supply and microbial biomass.
Aims This study aims to reveal the effects of soil warming on the fine root growth and morphological traits of subtropical evergreen broadleaf forests in China. Methods At the Fujian Sanming Forest Ecosystem National Observation and Research Station,we used an in-situ soil warming experiment and cooperated with the method of in-growth core in a Castanopsis kawakamii forest to explore fine root biomass growth and morphological traits during the rainy season(May)and dry season(November).In this study,we sorted fine roots into absorption roots(diameter＜1 mm)and transport roots(diameter 1-2 mm). Important findings Compared with the control,during the rainy season,soil warming treatment significantly reduced the biomass of absorptive roots by 41.2％,contrasting no changes of transport roots.Soil warming also did not alter the diameter and length of absorptive and transport roots,but specific root length(SRL)and specific root area(SRA)were significantly reduced by 53.2％and 42.9％,respectively,and root tissue density(RTD)was significantly increased by 28.8％in absorption roots.During the dry season,soil warming significantly increased the biomass of absorptive and transportive roots,as well as their root length(increased by 38.5％and 33.5％,respectively).However,the diameter,SRL,SRA,and RTD of absorptive and transport roots did not alter in soil warming treatment during the dry season.These results suggest that fine roots of Castanopsis kawakamii in mid-subtropical forests exhibited higher plasticity to cope with climate changes,such as adjusting absorptive root traits to alleviate the effect of soil warming on the resource absorption and growth during the rainy season,and increasing root length to expand resource absorption space during the dry season.This study provides a scientific basis for understanding the ecological adaptation and resource acquisition strategies of functionally distinct fine roots in subtropical forests under global warming.
植物元素含量及其计量关系在塑造功能性状中发挥着重要作用,同时调控着植物的生长发育和生殖(Sterner & Elser,2002).在一定程度上,植物器官化学计量特征与水力性状、经济谱性状等功能性状密切耦合,反映了植物在长期进化过程中对环境的适应策略(Wright et al.,2004;Reich,2014;Anderegg et al.,2016;He et al.,2020).近年来,植物生态化学计量特征与功能性状的生物地理格局、形成机制及对全球变化的响应等成为生态学研究的热点(Manzoni et al.,2008;Manu et al.,2024;González et al.,2025;He et al.,2025;Yang et al.,2025),研究范围涵盖了水生和陆生生态系统中的多种植物类群(Elser et al.,2009;Taylor & Townsend,2010;Peñuelas et al.,2013;Inomura et al.,2022;田地等,2026),研究对象也由传统的碳、氮、磷扩展到硫、钙、硅等元素(Ksionzek et al.,2016;Bauters et al.,2022;Ding et al.,2025),由叶片性状扩展到根、茎、花等多器官性状(Carmona et al.,2021;de Bello et al.,2021;李沁等,2026).
Aims Goosegrass(Eleusine indica),one of the world's malignant weeds,is also a widespread weed in the cotton(Gossypium hirsutum)fields along the Yangtze River in Anhui.Cotton is highly sensitive to weed competition.This research aims to determine the density competition effect of goosegrass on cotton and to identify its critical period for control,thereby allowing farmers to make well-formed decisions to further improve the management of goosegrass in cotton fields. Methods From 2010 to 2012,two experiments were conducted at an experimental site in Anqing,Anhui.In the density competition experiment,an additive series was used.The cotton density was kept constant while eight densities of goosegrass(0,0.125,0.25,0.5,1,2,3,and 4 plants·m-1)were tested.This aimed to determine the effects of varying goosegrass densities on cotton growth and yield.In the critical control period experiment,different durations of weed interference and weed-free periods(0,2,4,6,8,10,12,14 and 20 weeks after crop emergence)were investigated to determine how goosegrass affects cotton. Important findings As the density of goosegrass increased,its plant height gradually decreased.Compared to 0.125 plants m-1 goosegrass,the plant height of goosegrass at densities of 3 plants·m-1(2011)and 0.25 plants·m-1(2012)was significantly decreased.On average over three years,goosegrass biomass per unit area increased from 715 kg·hm-2(0.125 plants·m-1)to 4 148 kg·hm-2(4 plants·m-1).This indicates that intraspecific competition among goosegrass becomes more pronounced at higher densities.In 2012,the number of tillers and biomass per plant of goosegrass gradually increased with increasing weedy duration,and the height of goosegrass exceeded that of cotton during the first 12 weeks after crop emergence.With the increasing weed densities,the plant height and stem diameter of cotton decreased,while the number of fruit branches and bolls per plant were significantly reduced.The single boll mass was also reduced at higher densities of goosegrass,however,weed density did not significantly change the lint percentage.In 2012,the plant height of cotton significantly decreased at densities of over 2 plants·m-1.The cotton stem diameter was remarkably reduced at densities of 3 plants.m-1 or more in 2011 and 4 plants·m-1 in 2012,respectively.Goosegrass even at the density of 1 plants·m-1 reduced the fruit branch numbers,the boll number per plant and single boll mass of cotton by 8.7％to 11.6％,18.6％to 35.2％and 0.1％to 4.6％,respectively.The seed cotton yields were significantly reduced at densities of 0.125 plants·m-1(2010 and 2012)and 0.25 plants·m-1(2011),with reductions ranging from 10％to 18％.The boll number per plant of cotton and seed cotton yield loss rate followed a hyperbolic model in response to goosgrass density.It is predicted that goosegrass at a density between 2.3 to 3.7 plants·m-1 would result in a 50％reduction in the number of bolls per plant,while densities of 0.05 to 0.09 plants·m-1 would lead to a 5％reduction in seed cotton yield.The increased competition duration of goosegrass resulted in a gradual decline in the height and stem diameter of cotton plants.The increased competition duration also significantly reduced the number of fruit branches and bolls per plant.A Logistic relationship exists between the seed cotton yields and the competition duration of goosegrass.Conversely,with an increasing weed-free duration,cotton plants exhibited greater height and stem diameter,along with a notable rise in the number of fruit branches,bolls per plant,and seed cotton yield.The increase in seed cotton yield with prolonged weed-free duration followed a Gompertz model.The critical period for controlling goosegrass at a density of 2.5 plants·m-1 was between 35 to 83 days after cotton planting,based on a 5％yield-loss threshold.
Aims Ziziphus jujuba is a typical xerophytic shrub.Clarifying the variation of its root functional traits and the relationships between root traits and soil properties can enhance the understanding of plant resource-acquisition strategies and provide a scientific basis for the sustainable management of Z.jujuba shrub. Methods This study selected 24 Z.jujuba populations in different habitats in the Lincheng County,Xingtai City,which is the genuine medicinal material producing area of Ziziphi Spinosae Semen,as the research objects.The morphological,architectural,and chemical traits of Z.jujuba roots and soil properties were measured and analyzed to clarify the root economics space of Z.jujuba and the relationships between root traits and environmental factors. Important findings(1)The variation in the architectural traits(i.e.,branching ratio and branching intensity)of Z.jujuba was significantly higher than that in morphological(i.e.,root diameter and specific root length)and chemical(i.e.,root nitrogen and carbon content)traits.At the intraspecific level,there was a two-dimensional root economics space for the root functional traits of Z.jujuba.The first dimension was dominated by the trade-off between specific root length/specific root area and root diameter/tissue density,representing the transition of root resource-acquisition strategy from autonomous foraging(i.e.,developing higher specific root length and specific root area)to mycorrhizal cooperation.The second dimension was composed of negatively correlated root tissue density/diameter and root nitrogen/carbon content,representing the trade-off dimension between root defense and resource acquisition.(2)Soil environments affected the resource acquisition of Z.jujuba roots.In soil with higher total phosphorus,total potassium or sand content and lower pH,water content or organic carbon content,Z.jujuba roots tended to adopt an autonomous foraging strategy.On the contrary,Z.jujuba roots tended to adopt a mycorrhizal cooperative strategy for resource acquisition.(3)Redundancy analysis showed that soil water content(9.29％),total phosphorus content(6.12％),silt content(3.87％),and clay content(2.96％)were the main environmental factors affecting the variation of Z.jujuba root traits.Specific root length and specific root area of Z.jujuba were increased to acquire resource under dry conditions,and root diameter was increased to enhance its adaptability in low-phosphorus environments.There was a balance between resource acquisition and survival defense of Z.jujuba through the synergistic adjustment of root traits.And its resource strategy was driven by both environmental heterogeneity and long-term evolutionary selection.
Aims Exploring the differences in the life strategies of the"twig system"(old twig,new twig and leaf)of Corylus mandshurica in different seasons can provide a theoretical basis for the protection and management of wild C.mandshurica.At the same time,it can promote the understanding of the multi-organ coordinated response of plants to climate change. Methods In this study,taking the dominant species in the shrub layer of the broad-leaved Korean pine forest,C.mandshurica,as an example,nine traits including carbon,nitrogen,phosphorus,soluble sugar,starch,total non-structural carbohydrates,total phenol,tannin and flavonoid contents in the old twigs,new twigs and leaves of C.mandshurica were measured in three seasons,namely spring(May),summer(July)and autumn(September). Important findings The results showed that,except that the effect of the organ on starch was not significant,the season,the organ and their interaction had a relatively significant effect on the functional traits of C.mandshurica.In spring and summer,the contents of total phenol and tannin in the old twigs were relatively high,while in autumn,the contents of soluble sugars and other substances were relatively high.In spring,the nitrogen content in the new twigs was relatively high,while in summer and autumn,the contents of total non-structural carbon,tannin,flavonoid and other substances in the new twigs were relatively high.In spring and summer,the nitrogen and phosphorus contents in the leaves were relatively high,while in autumn,the contents of flavonoid and other substances in the leaves were relatively high.In addition,in spring and summer,compared with the new twigs and old twigs,the trait correlation network of the leaves was more complex;in autumn,the situation was the opposite.This reflects that in the"twig system"(old twig,new twig and leaf)of C.mandshurica,in spring,the leaves and new twigs tend to adopt a"growth"strategy,and the old twigs tend to adopt a"defense"strategy;in summer,the leaves tend to adopt a"growth"strategy,while the new twigs and old twigs tend to adopt a"defense"strategy.In autumn,the leaves tend to adopt a"defense"strategy,and the new twigs and old twigs tend to adopt a"resource recycling"strategy.The research results reveal that there are differences in the growth and defense strategies of the"twig system"of C.mandshurica,which is conducive to promoting the theoretical research on how plants respond to environmental changes towards the direction of systematization and refinement.
Aims In view of the expanding area of saline-alkaline land and the decline of maize(Zea mays)yield in Yinhuang Irrigation District of Ningxia,it is important to explore the effect of vertical deep rotary tillage with organic fertilizer on the aging characteristics of maize leaves and yield,which can provide theoretical basis for delaying the aging of maize and boosting yield in saline-alkaline land of this region. Methods The study was carried out in Pingluo,Ningxia in 2021-2022.Two types of tillage methods including conventional tillage(TF,tilling depth 25-30 cm)and vertical deep rotary tillage(DT,depth 40-45 cm)were set as main zones,and four levels of organic fertilizers including 0 kg·hm-2(M0),7 500 kg·hm-2(Ml),15 000 kg·hm-2(M2)and 22 500 kg·hm-2(M3)were set as sub-zones for analyzing the yield and leaf senescence characteristics of maize in saline-alkaline land. Important findings(1)In the DT plus M2 treatment,the yield of maize was significantly increased,and the amount of organic fertilizer should be kept between 14 505-16 710 kg·hm-2 to maximize the yield;under this treatment,the leaf area index(LAI)and relative chlorophyll content(SPAD)of maize were significantly increased,and the onset of leaf senescence was delayed by 1.7-2.19 d.(2)Compared with other treatments,DT with organic fertilizers decreased soil pH and electrical conductivity(EC),proline(Pro)and malondialdehyde(MDA)contents,and increased the contents of alkaline nitrogen(AN),available phosphorus(AP),available potassium(AK),and organic matter(OM).The activity of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),and the contents of soluble sugar(SS)has significantly increased.The M2 treatment was the best among the four treatments.Compared with the M2 treatment,excessive organic fertilizer input(M3)increased soil pH,EC,and MDA content,and decreased nutrient content,SOD activity,POD activity,CAT activity,SS content,and Pro content,which inhibited the growth and yield of maize.(3)Pearson correlation analysis showed that maize yield was significantly or highly significantly positively correlated with leaf LAI,SPAD,SOD activity,POD activity,CAT activity,Pro content,SS content,soil AN content,AK content,and OM content,and significantly or highly significantly negatively correlated with MDA content and EC.(4)The principal component analysis showed that the composite scores of M2＞M3＞M1＞M0 under vertical deep rotary tillage with organic fertilizer treatment.In this study,vertical deep rotary tillage with 15 000 kg·hm-2 organic fertilizer could effectively improve the saline soil environment,delay leaf senescence,increase leaf antioxidant enzyme activity,and reduce the accumulation of MDA,which in turn could stimulate the yield of maize.
Aims The stoichiometric characteristics of plant leaves are closely linked to their physiological and ecological functions,such as photosynthesis and water-use efficiency.Among tree species within the same habitat,variations in leaf stoichiometry reflect distinct strategies for utilizing environmental and nutritional resources.In China's Saihanba region,extensive plantations of Larix gmelinii var.principis-rupprechtii and Pinus sylvestris var.mongholica exhibit declining productivity and weakened ecosystem services,largely due to a lack of theoretical knowledge to inform traditional nutrient management.The objective of this study was to clarify the adaptive divergence and driving factors controlling the nutrient-use patterns of the dominant species used for afforestation projects and to use this knowledge to provide scientific guidance for tree species selection and ecosystem enhancement in semi-arid regions. Methods We established permanent field plots in the Saihanba region and collected leaf and soil samples from both dominant species in these plots to measure their carbon(C),nitrogen(N),and phosphorus(P)content.We used Redundancy analysis(RDA)and mixed-effects models to identify key environmental drivers of variations in their leaf stoichiometry. Important findings 1)Total soil C,N and P contents in the L.gmelinii var.principis-rupprechtii forest were higher than those in the P.sylvestris var.mongholica forest.The total N and P contents in the leaves of L.gmelinii var.principis-rupprechtii,as well as the intraspecific variation in N-related nutrient stoichiometric ratios,were all higher than those of P.sylvestris var.mongholica,while the leaf C content was lower than that of P.sylvestris var.mongholica;2)In terms of the environmental factors driving the stoichiometric characteristics of leaves,the influence of soil nutrient content surpassed that of atmospheric variables.Total soil C content accounted for 57.39％of the variation,followed by the mean annual air temperature,which explained 15.77％of the variation;3)With rising mean annual air temperature,leaf P content of L.gmelinii var.principis-rupprechtii decreased and leaf C∶P and N∶P ratios increased significantly.These findings suggest that P.sylvestris var.mongholica adopts a"conservative strategy"by maintaining relatively stable leaf N and P concentrations and constant N∶P ratios as an adaptation to low-resource environments,while L.gmelinii var.principis-rupprechtii employs an"active/acquisition strategy"characterized by higher N,P concentrations and flexible C∶P and N∶P ratios responsive to environmental shifts.This study elucidates the stoichiometric divergence between the two tree species,offering a theoretical foundation for future experiments on nutrient regulation and mechanistic exploration of their eco-physiological processes.
Aims This study aimed to reveal variations in ecological stoichiometric characteristics of plant roots and soils in coastal wetlands along a latitudinal gradient,to examine root stoichiometric homeostasis,and to explore the coupling relationships between root stoichiometry and environmental factors. Methods Plant and soil samples were collected from seven coastal wetlands across China spanning a latitudinal range from 19.87° to 41.03° N.The contents of carbon(C),nitrogen(N),and phosphorus(P)were measured in aboveground plant parts,roots,and soils.The relationships between plant root stoichiometric characteristics and environmental factors were further analyzed. Important findings Latitudinally driven environmental changes significantly influenced soil nutrient conditions,with soil nutrients in high-latitude coastal wetlands generally lower than those in low-latitude regions.The contents of soil organic carbon(＜11.1 g·kg-1)and total nitrogen(＜1.1 g·kg-1)north of Hangzhou Bay were lower than the national average.The C,N,and P stoichiometric characteristics of plant roots in coastal wetlands were relatively sensitive to latitudinal variation.These variations were closely related to soil nutrient conditions and varied among plant species.The root C content of Spartina alterniflora was extremely significantly positively correlated with soil nutrient conditions.The root C contents of Phragmites australis and × Bolboschoenoplectus mariqueter were significantly negatively correlated with soil nutrient conditions,whereas the root C,N,and P contents and their stoichiometric ratios of Suaeda salsa were significantly positively correlated with soil nutrient conditions.The six plant species also exhibited significant differences in root stoichiometric homeostasis,with the strength of homeostasis decreasing in the order of Avicennia marina,Phragmites australis,Spartina alterniflora,× Bolboschoenoplectus mariqueter,Aegiceras corniculatum,and Suaeda salsa.These results elucidate nutrient dynamics and plant adaptive strategies in plant-soil systems along latitudinal gradients and provide a theoretical basis for vegetation restoration in coastal wetland ecosystems.
Aims Clarify the variation patterns and corresponding response mechanisms of plant functional traits and carbon-nitrogen stoichiometry in artificial plantations of different tree species under the age gradient. Methods In this study,Populus tomentosa,Platycladus orientalis and Styphnolobium japonicum at different ages were selected as the research objects to determine and explore the changes and relationships of different organ functional traits,carbon-nitrogen stoichiometry and soil physicochemical properties. Important findings(1)With the increase of forest age,the content of soil nutrients,clay and silt of different tree plantations increased significantly.While soil total phosphorus content of Populus tomentosa plantations,and soil pH value of Platycladus orientalis plantations decreased.(2)The specific leaf area of different tree species increased significantly with the increase of forest age,while the specific leaf mass decreased significantly.The root carbon content(average 36.25％)was lower than that of branches(45.52％)and leaves(44.83％),and the leaf nitrogen content(1.98％)was higher than that of roots(1.30％)and branches(0.64％).With the increase of forest age,the nutrient content and carbon-nitrogen ratio of different organs varied with tree species.(3)The functional traits of Populus tomentosa plantations of different organs were coordinated,while the functional traits of leaves and roots of Platycladus orientalis plantations evolved independently,forming a decoupling strategy.(4)The increase of soil water content and the improvement of soil texture are important reasons for the changes in plant traits.(5)The soil total nitrogen content was significantly negatively correlated with the carbon content in leaves and roots.Redundancy analysis showed that soil electrical conductivity significantly affected plant functional traits.(6)Random forest analysis showed that the significant factors affecting the carbon-nitrogen ratio of leaves,branches and roots included soil total phosphorus and clay contents,specific leaf area,leaf dry matter mass and plant nutrient content.The research results reveal the differences in plant functional traits and organ carbon and nitrogen distribution among different tree species under the forest age gradient,enriching the theoretical framework of the plant economic spectrum.
Aims Saline alkali land is an important reality and potential agricultural resource to solve the shortage of arable land in China.Efficient utilization of saline alkali land resources to develop peanut(Arachis hypogaea)planting in such environments and achieve high and stable yield has become an urgent demand for ensuring peanut production.Under saline alkali stress habitat,arbuscular mycorrhizal fungi(AMF)can effectively develop potential productivity of host plants and improve their salt resistance and tolerance.Although it has been demonstrated that AMF enhanced peanut salt tolerance under salt stress,however,there have been limited reports on the effects of AMF on the growth and development of salt-tolerant and salt-sensitive peanut. Methods This study was investigated the response mechanisms of peanut growth and rhizosphere soil environment to AMF under saline-alkali conditions,aiming to provide theoretical basis and technical support for AMF application in peanut production in saline alkali soils.The experiment used salt-tolerant cultivar'HY25'and salt-sensitive cultivar'HY22'as experimental materials,with AMF seed coating treatment applied under saline alkali and normal soil conditions. Important findings Under two soil conditions,salt-tolerant and salt-sensitive peanut cultivars demonstrated differential response mechanisms to AMF inoculation.Under both soil environments,AMF improved the agronomic characteristics in'HY25',optimized photosynthetic parameters,and significantly increased pod yield.While AMF exhibited partial inhibitory effects on agronomic traits in'HY22'in normal soil,it notably improved leaf photosynthetic performance and elevated both pod yield and quality.Significant differences were found in the response of root growth of two cultivars to AMF including:1)In normal soil,the promoting effect of AMF on the growth of'HY25'root system initiated during the flowering-pegging stage and continued to until maturation stage.Under saline-alkaline soil,AMF significantly increased total root length,root surface area,and root volume in'HY25'at pod-setting stage.2)Salt-sensitive cultivar'HY22'exhibited greater sensitive to AMF inoculation.Under both normal and saline-alkali soils,AMF demonstrated inhibitory effects on root growth in'HY22'during flowering-pegging and/or pod-setting stages,with significantly stronger inhibition observed under saline-alkali soil than normal soil.Moreover,AMF effects on rhizosphere soil properties included:1)significant elevation in available phosphorus contents in both cultivars under two soil conditions;2)increased soil catalase,phosphatase,and invertase activities in both cultivars in saline alkali soil;whereas 3)significant inhibition of soil enzymatic activities in'HY22'under normal soil.These results indicated that compared to salt-sensitive cultivar,salt-tolerant cultivar might serve as more efficient symbiotic partner for AMF.AMF might demonstrate superior growth promotion in salt-tolerant cultivar,effectively exerting the synergistic effect of microbial regulation under saline-alkali soil.
Aims Tropical and subtropical areas are hotspots for the distribution of artificial forests in our country.Clarifying the status and influential factors of plant biomass in typically mixed artificial forests in these areas is important.This can help to uncover the limiting factors for stand productivity and guide the management of artificial forests. Methods In this study,we selected a conifer-broadleaf mixed forest in Yunyong forestry station located in Foshan,Guangdong.This forest was transformed from a Chinese fir plantation.First,we compared the difference in biomass of each plant organ among tree species configuration modes at the early recovery stage(8-16 a).Second,the shifts in soil physicochemical properties and community-level plant functional traits under different conditions of tree species configuration were characterized.Finally,we explored the relative contributions of tree species configuration,soil properties and plant leaf traits to variations in plant biomass,and evaluated their influential pathways.Based on these analyses,we aimed to evaluate the key influential factors for plant biomass in artificial forests in south subtropical areas. Important findings Our results showed that both plant and organ biomass differed significantly under different tree species configuration modes.Tree species configurations affected plant biomass mainly via regulating leaf functional traits and soil nutrient content.Moreover,leaf functional traits had greater influence on foliage and branch biomass,while the variation in soil nutrient content was the main factor driving the changes in truck,roots and total plant biomass.Specifically,tree species configurations characterized by a higher ratio of leaf nitrogen(N)∶phosphorus(P)and a higher functional diversity had greater biomass in plant communities.An increase in soil total P content significantly promoted the increase in plant biomass,while an excess in soil total potassium would suppress the growth in biomass.This study compared the relative effects of leaf functional traits and soil nutrient content on plant biomass in the typically mixed artificial stands in south subtropical forests,and explored the key influential factors for the biomass in total and in each organ.These results provided the theoretical bases for restoration,operation and management of the artificial forests in south subtropical areas.
Aims Elevated atmospheric ozone(O3)concentrations significantly affect plant nutrient allocation,thereby regulating litter decomposition.However,the stoichiometric responses of leaf and fine root litters to O3 stress remain unclear.This study aimed to investigate how elevated O3 influenced the dynamics and regulatory mechanisms of carbon(C),nitrogen(N),and phosphorus(P)stoichiometry during the decomposition of leaf and fine root litter. Methods A 12-month decomposition experiment was conducted using Koelreuteria paniculata and Camellia sinensis at the O3-FACE platform in Yanqing,Beijing.We applied two treatments i.e.,ambient air(NF)and elevated O3(NF60,ambient air+60 nmol·mol-1 O3).At four decomposition stages(0,1,3,and 12 month),we measured litter C,N,and P concentrations and stoichiometric ratios(C∶N,C∶P,N∶P). Important findings Elevated O3 concentration significantly altered the initial stoichiometric structure and residual characteristics of the litter.Under NF60,the initial C∶N ratio of K.paniculata leaves increased by 7.6％,while N∶P decreased by 17.7％,leading to a 10.3％increase in mass remaining after 12 months.In C.sinensis fine root litter,phosphorus(P)concentration increased by 11.1％and the C∶P ratio decreased by 14.5％,showing organ-and species-specific stoichiometric shifts.Litter mass remaining(％)was significantly correlated with C∶N,C∶P,and N∶P ratios.During decomposition,the N∶P ratio of leaf litter increased significantly in both species(K.paniculata:43.6％-68.0％;C.sinensis:52.9％-59.3％),indicating enhanced P limitation in the later stages.Consistent with the microbial growth rate hypothesis,fine root litter also exhibited organ-specific increases in N∶P,but the magnitude and treatment effects depended on species.O3 altered litter stoichiometric characteristics,particularly C∶P balance,which may have influenced microbial nutrient acquisition and contributed to slower carbon turnover;moreover,leaf litter and fine roots showed distinct response patterns.Leaves and fine roots exhibited contrasting responses:K.paniculata leaves were more constrained by P availability,while C.sinensis fine roots maintained higher decomposition efficiency through enhanced P redistribution.These findings highlight organ-specific adaptive strategies under O3 stress and provide novel insights into stoichiometric regulation of litter decomposition under global change.
Aims Urban forests serve as ecological barriers that mitigate urban heat island effects and enhance ecosystem services,attracting increasing attention to their structure and function.Functional traits are essential for characterizing plant ecological strategies and revealing their regulatory effects on ecosystem processes.Most existing studies have focused on natural ecosystems,while the ecological strategies and functional roles of dominant tree species in urban forests remain poorly understood. Methods This study focused on six key species(Robinia pseudoacacia,Eucommia ulmoides,Styphnolobium japonicum,Acer truncatum,Pinus tabuliformis,and Ginkgo biloba)in Beijing plain forests.Four categories of leaf functional traits,including morphological,elemental,chemical defense,and hydraulic traits,were measured to elucidate interspecific differences in ecological strategies and to characterize the network structure of leaf functional traits. Important findings Significant interspecific differences in leaf functional traits and corresponding ecological strategies were found:Pinus tabuliformis exhibited the lowest specific leaf area and lowest water potential at turgor loss point,reflecting a strategy that prioritizes resource conservation and drought resistance;Acer truncatum showed high specific leaf area and the highest total phenolic content,representing a strategy of rapid resource acquisition with strong chemical defense;Robinia pseudoacacia had the highest leaf nitrogen content with moderate total phenolic levels,indicating fast growth with basic chemical defense as a strategy;Styphnolobium japonicum possessed the highest phosphorus content and lowest total phenolic content,suggesting a strategy of rapid growth with low chemical defense investment;Eucommia ulmoides displayed high leaf dry matter content and carbon concentration,reflecting moderate resource conservation and investment in structural defense;Ginkgo biloba exhibited intermediate-low values in growth-defense traits,representing a balanced growth with low chemical defense strategy.The leaf trait network constructed from the six species(edge density=0.37,diameter=4,average path length=1.90,clustering coefficient=0.59,modularity=0.26)revealed a relatively simple structure,with specific leaf area acting as the central hub connecting different functional modules.This pattern reflects an initial stage of functional differentiation under the"fast-growth and high-efficiency"management orientation of Beijing plain forests,while also implying potential ecological vulnerability.Overall,this study provides new insights into the functional positioning of urban forest species and offers a theoretical basis for enhancing the multifunctionality of plain forests.
Aims The impoundment of the Three Gorges Reservoir(TGR)has led to the transformation of a large number of natural riparian zones into reservoir drawdown zones,characterized by reverse seasonal water level fluctuations.This transformation has fundamentally altered the local habitat,significantly impacting the differentiation of plant morphological traits.This study aims to reveal the impact of habitat transformation from"riverbank to drawdown zone"as a result of the TGR backwater disturbance on the functional trait differentiation of adapted herbaceous plants as well as their adaptation strategies. Methods This study used a typical small watershed(Baijiaxi)in TGR area as a case.Four herbaceous plant species(Cynodon dactylon,Bidens tripartita,Xanthium strumarium,and Polygonum hydropiper)suitable for the local environment were selected as objects.The spatial differentiation characteristics of 17 plant functional trait indicators were analyzed across the habitat transformation from the riparian zone to the drawdown zone.Pearson correlation analysis was employed to explore the co-evolutionary relationships among functional traits,while redundancy analysis(RDA)was conducted to assess the influence of habitat factors on the differentiation of these traits. Important findings(1)The transition from natural riparian habitats into the drawdown zone resulted in significant variations in the morphological traits of the four plant species.These variations were characterized by increased plant height and decreased root length.These changes were primarily attributed to the restricted growth period imposed by water-level fluctuations and the relatively simplified plant community structure with reduced competitive pressure.Concurrently,leaf thickness increased,and leaf area expanded in most plants,which was mainly driven by intensified drought stress during summer in the drawdown zone.The results highlighted that the backwater effects of the TGR significantly amplified local-scale shape variations among species.(2)The chlorophyll content and net photosynthetic rate of leaves in the four plant species were significantly higher in the drawdown zone compared to those in the natural riparian zone,indicating that plants may have developed an adaptation strategy to enhance photosynthetic efficiency and accelerate growth rates in response to habitat limitations.(3)Under the habitat screening effect of the backwater in the TGR,the four plant species developed a trade-off strategy between"growth"and"drought tolerance",showing convergent adaptation strategies.Cynodon dactylon exhibited stronger phenotypic variability,especially in photosynthetic traits,suggesting greater adaptability to habitat changes.In contrast,Bidens tripartita,Xanthium strumarium,and Polygonum hydropiper formed more conservative adaptation strategies.(4)RDA showed that variations in functional traits of the four plant species within the upstream riparian zone were primarily associated with soil moisture.While,in the midstream and downstream drawdown zone,these variations were predominantly linked to flooding depth,soil pH and soil temperature,indicating that differences in flooding regimes drove the differentiation of plant functional traits.
In line with the evolution of fundamental concepts and theories in the discipline,ecology persists in developing its conceptual and theoretical framework.This paper puts forward and expounds on the potential foundational princi-ples of ecology through the application of analytical,synthetic,and dialectical methods.(1)Scale-dependent prin-ciple.The regularities and mechanisms governing ecological processes are contingent upon spatial and temporal scales,as well as ecological organization or hierarchy.Corresponding concepts and theories are typically formu-lated for specific scales.Constructing a comprehensive theory that spans all scales continues to pose a substantial challenge.(2)Dynamic equilibrium principle.Considering the openness of ecosystems,especially their biological and ecological metabolic characteristics,a specific stage in an ecological process or a particular state of an eco-system can only attain a dynamic equilibrium.The nature of this equilibrium depends on the system's inherent regulatory capacity,encompassing both resistance and resilience,as well as the stage of succession.Typically,the climax of ecological succession signifies a stable equilibrium state for the ecosystem or community.Following this climax,the system may possibly shift into a non-equilibrium condition.(3)Feedback interaction principle.Feedback interactions play a crucial role in determining and regulating the nature and function of ecological proc-esses and systems.Positive feedback can lead to unidirectional amplification or diminishment of these processes,while negative feedback generally maintains the equilibrium of ecological systems,including biological homeo-stasis.The dynamic balance between positive and negative feedback mechanisms within the ecological-evolutionary process governs the stability or instability of ecosystems.In actuality,the scale-dependent principle addresses the overarching cognitive perspective of ecological phenomena and processes,while the dynamic equilibrium princi-ple focuses on the intrinsic nature of ecological processes or states.The feedback interaction principle,under-scores the core issues in ecology,particularly the interactions among living organisms and between living organ-isms and non-living entities.These fundamental ecological principles or rules exhibit both relative independence and a degree of compatibility,yet they are inherently and inevitably interconnected.Understanding and establish-ing the fundamental principles of ecology will not only facilitate the progress of ecological concepts and theories but also contribute to the development and improvement of the scientific framework of ecology.
Aims Plant functional traits reflect the trade-off mechanism for resource acquisition,and plants can be classified as resource-acquisitive and resource-conservative based on their trait combinations.Nitrogen(N)is essential for plant growth,and increased N deposition can affect plant traits and resource acquisition strategies by altering the ecosystem N cycle.However,most studies on the effects of N deposition on plant traits and strategies have focused on the tree layer,with relatively little research on understory plant communities,especially in boreal forests. Methods This study relied on a thirteen-year of N addition experiments in Larix gmelinii forests to explore the effects of N addition on understory plant traits at the species and community levels,and to analyse changes in plant resource use strategies. Important findings The results showed that N addition promoted plant height,specific leaf area and relative cover of acquisitive species(e.g.Betula fruticosa and Deyeuxia angustifolia),while it suppressed the plant height,relative cover and photosynthetic rate of conservative plants(e.g.Vaccinium vitis-idaea),suggesting that N addition favoured the growth of plants with acquisitive strategies.At the community level,N addition significantly promoted leaf N content,specific leaf area,and plant height;and significantly reduced leaf phosphorus content in community-weighted mean traits,and these changes were mainly caused by intraspecific variation.In contrast,N addition did not significantly change the functional dispersion of most traits,and these changes were mainly related to interspecific variation.More importantly,the changes in community traits reflect that N addition has shifted in the resource use strategy of boreal forest understory plant communities from conservative to acquisitive.In summary,this study reveals how long-term N addition changes resource use strategies of boreal forest understory plant communities and their relationship with plant community composition and growth response.
Aims Under the background of global climate change,this study investigated the dynamic characteristics of energy fluxes in Jinyun Mountain's coniferous-broadleaf mixed forest across different temporal scales and their responses to environmental factors. Methods We selected the mixed coniferous and broadleaf forests in Jinyun Mountains as the study area,and analyzed the long time series flux data of the mixed coniferous and broadleaf forests in Jinyun Mountains for the years 2020,2021,and 2023(data for 2022 are missing)using correlation factor analysis and structural equation modeling based on the data measured by eddy correlation technique. Important findings(1)At the diurnal scale,net radiation(Rn),sensible heat flux(H),and latent heat flux(LE)exhibited unimodal trends,with their peak values occurring at 14:00 local time,and approaching near-zero values after 19:00.In contrast,soil heat flux(G)displayed a bimodal pattern,reaching its daily minimum prior to sunrise and attaining its daily maximum at 14:00 local time.(2)At the monthly scale,the influence of Rn on energy fluxes increased from April,reached its maximum in July and August,then gradually decreased.The influence of canopy conductance(Gs)on LE followed the same trend.(3)At the growing season scale,Rn was the primary influencing factor for energy flux variations.Correlation factor analysis indicated that Gs had a slight limiting effect on H but a significant limiting effect on LE.However,the plant water balance mechanism exerted the strongest influence.(4)The annual mean Bowen ratios(β)for the three years were 0.69,0.63,and 0.76,respectively.(5)Influenced by extreme drought,the sensible heat flux at the annual scale exhibited a bimodal trend.This study analyzed the characteristics and influencing factors of energy fluxes in the Jinyun Mountain coniferous-broadleaf mixed forests,revealing the dynamic processes of energy fluxes,quantifying the impacts of environmental factors,and providing a scientific basis for assessing the response of subtropical forest ecosystems to climate change and forest conservation.
