Under current climate warming, the growth resilience of plantation forests after extreme droughts has garnered increasing attention. Platycladus orientalis Linn. is an evergreen tree species commonly used for afforest...Under current climate warming, the growth resilience of plantation forests after extreme droughts has garnered increasing attention. Platycladus orientalis Linn. is an evergreen tree species commonly used for afforestation, and the stability of P. orientalis plantation forests in the Loess Hilly region directly affects the ecological and environmental security of the entire Loess Plateau of China.However, systematic analyses of the growth resilience of P. orientalis plantation forests after extreme droughts along precipitation gradients remain scarce. In this study, we collected tree ring samples of P.orientalis along a precipitation gradient(255, 400, and 517 mm) from 2021 to 2023 and used dendroecological methods to explore the growth resilience of P. orientalis to drought stress on the Loess Plateau. Our findings revealed that the growth resilience of P. orientalis increased with increasing precipitation, enabling the trees to recover to the pre-drought growth levels. In regions with low precipitation(255 mm), the plantation forests were more sensitive to extreme droughts, struggling to recover to previous growth levels, necessitating conditional artificial irrigation. In regions with medium precipitation(400 mm), the growth of P. orientalis was significantly limited by drought stress and exhibited some recovery ability after extreme droughts, therefore warranting management through rainwater harvesting and conservation measures. Conversely, in regions with high precipitation(517 mm), the impacts of extreme droughts on P. orientalis plantation forests were relatively minor. This study underscored the need for targeted strategies tailored to different precipitation conditions rather than a "one-size-fits-all" approach to utilize precipitation resources effectively and maximize the ecological benefits of plantation forests. The findings will help maintain the stability of plantation forests and improve their ecosystem service functions in arid and semi-arid areas.展开更多
Based on data from a field survey in 2001 along the Northeast China transect (NECT), a precipitation gradient,and a short-term simulation experiment under ambient CO2 of 350 μmol mol-1 and doubled CO2 of 700 μmol mo...Based on data from a field survey in 2001 along the Northeast China transect (NECT), a precipitation gradient,and a short-term simulation experiment under ambient CO2 of 350 μmol mol-1 and doubled CO2 of 700 μmol mol-1with different soil moisture contents of 30%-45%, 45%-60%, and 60%-80% soil water holding capacity, the distributionof soil organic carbon and labile carbon along the NECT, their relationships with precipitation and their responses toCO2 enrichment and soil moisture changes were analyzed. The results indicated that the soil labile carbon along thegradient was significantly related to soil organic carbon (r = 0.993, P < 0.001). The soil labile carbon decreased morerapidly with depth than organic carbon. The soil organic and labile carbon along the gradient decreased with decrease inlongitude in both the topsoils and subsoils, and the coefficient of variation for the labile carbon was greater than that forthe organic carbon. Both the soil organic carbon and labile carbon had significant linear relationships with precipitation,with the correlation coefficient of soil organic carbon being lower (0.677 at P < 0.001) than that of soil labile carbon(0.712 at P < 0.001). In the simulation experiment with doubled and ambient CO2 and different moisture contents, thecoefficient of variation for soil organic carbon was only 1.3%, while for soil labile carbon it was 29.7%. With doubled CO2concentration (700 μmol mol-1), soil labile carbon decreased significantly at 45% to 60% of soil moisture content. Theseindicated that soil labile carbon was relatively more sensitive to environmental changes than soil organic carbon.展开更多
Bacteria in desert soil have unique phylogeny and important ecological functions, and theirresponses to changes in precipitation need further attention. However, relevant studies have mainlyfocused on the surface soil...Bacteria in desert soil have unique phylogeny and important ecological functions, and theirresponses to changes in precipitation need further attention. However, relevant studies have mainlyfocused on the surface soil, and studies on the responses of bacteria at different soil depths to variationsin precipitation are rare. Thus, we used 16S rDNA high-throughput sequencing to investigate the changesin soil bacterial distribution along a mean annual precipitation gradient (50–150 mm) in the Alxa Desert,China, and compared the variation characteristics in the surface soil layer (0–10 cm) and subsurface soillayer (10–20 cm). Results showed that soil bacterial communities significantly changed along theprecipitation gradient in both soil layers. However, the subsurface soil layer could support bacterialcommunities with higher diversity and closer internal relationships but more internal competition than thesurface soil layer. Additionally, compared with the surface soil layer, variations in diversity andco-occurrence patterns in the subsurface soil layer were more in line with the changes in the mean annualprecipitation, while bacterial community structure was less variable in the subsurface soil layer. Comparedwith the mean annual precipitation, soil moisture had little influence on the structure and diversity of soilbacterial community but had a high correlation with intercommunity connectivity. Therefore, soilmoisture might play a complex role in mediating environmental conditions and soil bacterial communitycharacteristics. Due to the different responses of surface and subsurface soil bacteria to the changes inprecipitation, it is necessary to distinguish different soil layers when predicting the trends in desert soilbacterial conditions associated with precipitation, and prediction of subsurface soil bacteria may be moreaccurate.展开更多
Nebkhas, discrete mounds of sand and vegetation, are a common landscape feature critical to the stability of desert ecosystems and supported by limited precipitation. Nebkha morphology and spatial pattern vary in land...Nebkhas, discrete mounds of sand and vegetation, are a common landscape feature critical to the stability of desert ecosystems and supported by limited precipitation. Nebkha morphology and spatial pattern vary in landscapes, but it is unclear how they change along precipitation gradients in arid and semi-arid regions. In this study we determined morphology and soil nutrient patterns of nebkha from different regions of northwestern China. The objective of this study was to understand zonal differences among nebkhas and how morphological characteristics and soil nutrient patterns of nebkha change along a precipitation gradient in northwestern China. Our results shows that mean annual precipitation(MAP) had significant effects on morphological characteristics of nebkhas such as height, area, and volume which significantly decreased with an increase in MAP. MAP had significant positive effects on shrub cover and species richness of nebkha. Soil nutrients such as soil organic matter(SOM), total carbon(TC), total nitrogen(TN), and total phosphorus(TP) in the 0-10 cm layer increased with an increase of MAP, and soil nutrient content within nebkhas was higher than in inter-nebkha areas.We concluded that nebkhas are "fertile islands" with an important role in ecosystem dynamics in study regions. Further,MAP is a key factor which determined zonal differences, morphological, and soil nutrients patterns of nebkhas. However,disturbance, such as animal grazing, and planted sand-stabilizing vegetation accelerated the degeneration of nebkha landscapes. We recommend implementation of protective measures for nebkhas in arid and semi-arid areas of China.展开更多
This study introduces a new dynamical quantity, shear gradient vorticity (SGV), which is defined as vertical wind shear multiplying the horizontal component of vorticity gradient, aiming to diagnose heavy precipitatio...This study introduces a new dynamical quantity, shear gradient vorticity (SGV), which is defined as vertical wind shear multiplying the horizontal component of vorticity gradient, aiming to diagnose heavy precipitation induced by some strong convective weather systems. The vorticity gradient component can be used to study the collision or merging process between different vortexes or the deformation of a vortex with a sharp vorticity gradient. Vertical wind shear, another contributed component of SGV, always represents the environmental dynamical factor in meteorology. By the combined effect of the two components, overall, SGV can represent the interaction between the environmental wind shear and the evolution of vortexes with a large vorticity gradient. Other traditional vorticity-like dynamical quantities (such as helicity) have the limitation in the diagnosis of the convection, since they do not consider the vorticity gradient. From this perspective, SGV has the potential to diagnose some strong convective weather processes, such as Extratropical Transition (ET) of tropical cyclones and the evolution of multicell storms. The forecast performance of SGV for the numerical ET case of Typhoon Toraji (0108) has been evaluated. Compared with helicity, SGV has shown a greater advantage to forecast the distribution of heavy precipitation more accurately, especially in the frontal zone.展开更多
The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are sti...The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are still controversial. We selected 717 grassland sites with ANPP and mean annual precipitation(MAP) data from 40 publications to characterize the relationships ANPP–MAP and PUE–MAP across different grassland types. The MAP and ANPP showed large variations across all grassland types, ranging from 69 to 2335 mm and 4.3 to 1706 g m^(-2), respectively. The global maximum PUE ranged from 0.19 to 1.49 g m^(-2) mm^(-1) with a unimodal pattern. Analysis using the sigmoid function explained the ANPP–MAP relationship best at the global scale. The gradient of the ANPP–MAP graph was small for arid and semi-arid sites(MAP <400 mm). This study improves our understanding of the relationship between ANPP and MAP across dry grassland ecosystems. It provides new perspectives on the prediction and modeling of variations in the ANPP for different grassland types along precipitation gradients.展开更多
Variations of precipitation have great impacts on soil carbon cycle and decomposition of soil organic matter.Soil bacteria are crucial participants in regulating these ecological processes and vulnerable to altered pr...Variations of precipitation have great impacts on soil carbon cycle and decomposition of soil organic matter.Soil bacteria are crucial participants in regulating these ecological processes and vulnerable to altered precipitation.Studying the impacts of altered precipitation on soil bacterial community structure can provide a novel insight into the potential impacts of altered precipitation on soil carbon cycle and carbon storage of grassland.Therefore,soil bacterial community structure under a precipitation manipulation experiment was researched in a semi-arid desert grassland in Chinese Loess Plateau.Five precipitation levels,i.e.,control,reduced and increased precipitation by 40%and 20%,respectively(referred here as CK,DP40,DP20,IP40,and IP20)were set.The results showed that soil bacterial alpha diversity and rare bacteria significantly changed with altered precipitation,but the dominant bacteria and soil bacterial beta diversity did not change,which may be ascribed to the ecological strategy of soil bacteria.The linear discriminate analysis(LDA)effect size(LEfSe)method found that major response patterns of soil bacteria to altered precipitation were resource-limited and drought-tolerant populations.In addition,increasing precipitation greatly promoted inter-species competition,while decreasing precipitation highly facilitated inter-species cooperation.These changes in species interaction can promote different distribution ratios of bacterial populations under different precipitation conditions.In structural equation model(SEM)analysis,with changes in precipitation,plant growth characteristics were found to be drivers of soil bacterial community composition,while soil properties were not.In conclusion,our results indicated that in desert grassland ecosystem,the sensitive of soil rare bacteria to altered precipitation was stronger than that of dominant taxa,which may be related to the ecological strategy of bacteria,species interaction,and precipitation-induced variations of plant growth characteristics.展开更多
Northeast China Transect(NECT),one of the fifteen International Biosphere-Geosphere Programme(IGBP)terrestrial transects,has been established for 10 years by Prof.Zhang Xin-Shi,through a core project of the IGBP--the ...Northeast China Transect(NECT),one of the fifteen International Biosphere-Geosphere Programme(IGBP)terrestrial transects,has been established for 10 years by Prof.Zhang Xin-Shi,through a core project of the IGBP--the Global Change and Terrestrial Ecosystems(GCTE).This transect is located in the mid-latitude semi-arid region,ranging 42–46°N latitude and 110–132°E longitude.The primary driving force for global change is precipitation and the secondary one is land use intensity.Research progresses have been performed during the past decade in the following aspects:ecological database development,climate and its variability,ecophysiological response of plants to environments,vegetation and landscape changes,biodiversity patterns and their changes,plant functional types and traits with relation to climatic gradient,productivity and carbon dynamics,pollen-vegetation relationship,trace gas emissions,land use and land cover changes,as well as biogeographical and biogeochemical modelling.In order to achieve the higher level of integrated research,the NECT needs the consistent basic data sets within the same framework,further field experiments and observations,integrated simulations of vegetation structure,process and function from patch,landscape to biome scales,intercomparisons ofresults and simulations within the transect and to other IGBP transects,multidisciplinary research,national and international co-ordinates,and full scientific plan and implementation strategy.展开更多
Background Changes in precipitation patterns crucially impact soil microbial communities,and the ecosystem in Qinghai-Tibet Plateau(QTP)is highly vulnerable to climate change.However,we do not fully understand how soi...Background Changes in precipitation patterns crucially impact soil microbial communities,and the ecosystem in Qinghai-Tibet Plateau(QTP)is highly vulnerable to climate change.However,we do not fully understand how soil microbial communities in the source wetlands of QTP respond to changes in precipitation.In this study,we employed advanced techniques such as high-throughput sequencing and metabolomics to investigate how soil microbial communities in a source wetland of Qinghai Lake respond to changes in precipitation after quadrennial precipitation treatment.Results Our findings showed that the predominant microbiota in the source wetland was Proteobacteria.Interestingly,alterations in precipitation levels,whether increased or reduced,did not significantly impact the diversity or functional groups of the microbial community.However,the structure of the microbial community did respond notably to changes in precipitation,leading to shifts in the relative abundance of Spirochaetes and Treponema.A notable finding was that reduced precipitation levels(–25%and-50%)and mild increases in precipitation(25%)within the region contributed to increased soil carbon content.However,this effect ceased to manifest when precipitation increased by 50%.Additionally,the reduction in precipitation prompted the release of soil metabolites like syringic acid and aldosterone,while enhanced precipitation resulted in a decrease in aldosterone content.Conclusions Precipitation changes altered the relative abundance of soil microbial communities and metabolites,which was conducive to increasing carbon storage in this alpine wetland.展开更多
Aims Both dominance distribution of species and the composition of the dominant species determine the distribution of traits within community.Leaf carbon(C)and nitrogen(N)isotopic composition are important leaf traits...Aims Both dominance distribution of species and the composition of the dominant species determine the distribution of traits within community.Leaf carbon(C)and nitrogen(N)isotopic composition are important leaf traits,and such traits of dominant species are associated with ecosystem C,water and N cycling.Very little is known how dominant species with distinct traits(e.g.N-fixing leguminous and non-leguminous trees)mediate resource utilization of the ecosystems in stressful environment.Methods Leaves of 81 dominant leguminous and non-leguminous trees were collected in forest(moist semi-deciduous and dry semi-deciduous ecosystems)and savanna(costal savanna,Guinean savanna and west Sudanian savanna ecosystems)areas and the transitional zone(between the forest and the savanna)along the transect from the south to the north of Ghana.We measured leaf traits,i.e.leafδ13C,leafδ15N,leaf water content,leaf mass per area(LMA)and C and N concentration.Correlation analyses were used to examine trait–trait relationships,and relationships of leaf traits with temperature and precipitation.We used analysis of covariance to test the differences in slopes of the linear regressions between legumes and non-legumes.Important Findings Leafδ13C,δ15N,leaf water content and LMA did not differ between leguminous and non-leguminous trees.Leaf N concentration and C:N ratio differed between the two groups.Moreover,leaf traits varied significantly among the six ecosystems.δ13C values were negatively correlated with annual precipitation and positively correlated with mean annual temperature.In contrast,leafδ15N of non-leguminous trees were positively correlated with annual precipitation and negatively correlated with mean annual temperature.For leguminous trees,such correlations were not significant.We also found significant coordination between leaf traits.However,the slopes of the linear relationships were significantly different between leguminous and non-leguminous trees.Our results indicate that shifts in dominant trees with distinct water-use efficiency were corresponded to the rainfall gradient.Moreover,leguminous trees,those characterized with relative high water-use efficiency in the low rainfall ecosystems,were also corresponded to the relative high N use efficiency.The high proportion of leguminous trees in the savannas is crucial to mitigate nutrient stress.展开更多
Plant roots show flexible traits to changing precipitation,but the factors driving root trait covariation remain poorly understood.This study investigated six key root traits and explored the potential driving factors...Plant roots show flexible traits to changing precipitation,but the factors driving root trait covariation remain poorly understood.This study investigated six key root traits and explored the potential driving factors,including plant community characteristics and soil properties,in the Zoige alpine meadow across five precipitation gradients:natural precipitation(1.0P),a 50%increasing precipitation(1.5P),and 30%,50%and 90%decreasing precipitation(0.7P,0.5P and 0.1P,respectively).Our results demonstrated distinct root trait responses to changes in precipitation.Both increasing(1.5P)and decreasing precipitation(0.1P,0.5P and 0.7P)inhibited root diameter(RD),specific root length(SRL)and specific root area compared with 1.0P.Conversely,root tissue density and root nitrogen content increased under decreasing precipitation but declined under 1.5P.With increasing precipitation,root foraging strategies shifted with thinner RD and larger SRL to that with a larger diameter.Shifts in root strategies were primarily influenced by soil properties,specifically soil water content and available nitrogen.Additionally,root strategies in surface soils(0-10 cm)were mainly related to the grass and sedge coverage,whereas in deeper soils(10-20 cm)root strategies were related to overall plant community coverage and biomass.Our findings indicate that root trait variations and strategies in alpine meadows are co-driven by soil properties and plant communities in response to changing precipitation.展开更多
The positive relationships between biodiversity and ecosystem productivity have been broadly recognized in aquatic and terrestrial ecosystems,such as grasslands.However,remotely sensed assessment of functional diversi...The positive relationships between biodiversity and ecosystem productivity have been broadly recognized in aquatic and terrestrial ecosystems,such as grasslands.However,remotely sensed assessment of functional diversity(FD)and its relationships with productivity across large regions are less studied in grasslands.In this study,we first examined the potential of spectral retrieval of 13 leaf functional traits from a species spectra-trait library to complement field measurements across three types of grassland communities in the Xinlingol grassland located in northern China.We then pre-selected the key traits out of 13 functional traits from 1664 plant individuals of 112 species to calculate in-situ productivity-related FD,and explored the multi-scale relationships of single-trait community weighed mean(CWM)and FD index(Rao’s quadratic entropy,RaoQ)with ecosystem productivity at plot level(1 m×1 m)and site level(30 m×30 m),respectively.Finally,we applied Sentinel-2 satellite data to infer regional FD through statistical relationships with direct spectral association using partial least squares regression(PLSR).With the leaf spectral prediction(cross-validation R^(2) cv=0.48-0.81)and in-situ measurement,CWM of organic acid detergent fiber(ADF),phosphorus(P),specific leaf area(SLA),chlorophyll(Chl),lignin(Lig)and carbon(C)together with RaoQ of ADF,C,N,Chl,SLA,and calcium(Ca)were selected to explain changes in ecosystem productivity(80%)at the plot level,while CWM of Car,Chl,Lig,NDF,NSC,P,and SLA together with RaoQ of C,SLA and non-structural carbohydrates(NSC)were selected to indicate productivity(94%)at site level.Furthermore,we found the combination of single-trait CWM(60%)outperformed that of RaoQ(34%)in determining ecosystem productivity at the site level compared with their almost equal contributions at plot level.At the regional scale,Sentinel-2 data could be used to infer these selected single-trait CWM and RaoQ values(R^(2) cv=0.32-0.82)and biomass(R^(2) cv=0.76),except for CWM and RaoQ of C(R^(2) cv=0.12-0.18).This study underscores the potential of Sentinel-2 satellite with leaf spectral measurements to monitor grassland functional diversity,informing the linkages between functional diversity and ecosystem functioning at regional scale.展开更多
基金funded by the National Natural Science Foundation of China (42071047)Innovation Fund Project for College Teachers in Gansu Province (2025A-008)+1 种基金Research Capability Enhancement Plan for Young Teachers at Northwest Normal University (NWNU-LKQN2024-19)Basic Research Innovation Group Project of Gansu Province (22JR5RA129)。
文摘Under current climate warming, the growth resilience of plantation forests after extreme droughts has garnered increasing attention. Platycladus orientalis Linn. is an evergreen tree species commonly used for afforestation, and the stability of P. orientalis plantation forests in the Loess Hilly region directly affects the ecological and environmental security of the entire Loess Plateau of China.However, systematic analyses of the growth resilience of P. orientalis plantation forests after extreme droughts along precipitation gradients remain scarce. In this study, we collected tree ring samples of P.orientalis along a precipitation gradient(255, 400, and 517 mm) from 2021 to 2023 and used dendroecological methods to explore the growth resilience of P. orientalis to drought stress on the Loess Plateau. Our findings revealed that the growth resilience of P. orientalis increased with increasing precipitation, enabling the trees to recover to the pre-drought growth levels. In regions with low precipitation(255 mm), the plantation forests were more sensitive to extreme droughts, struggling to recover to previous growth levels, necessitating conditional artificial irrigation. In regions with medium precipitation(400 mm), the growth of P. orientalis was significantly limited by drought stress and exhibited some recovery ability after extreme droughts, therefore warranting management through rainwater harvesting and conservation measures. Conversely, in regions with high precipitation(517 mm), the impacts of extreme droughts on P. orientalis plantation forests were relatively minor. This study underscored the need for targeted strategies tailored to different precipitation conditions rather than a "one-size-fits-all" approach to utilize precipitation resources effectively and maximize the ecological benefits of plantation forests. The findings will help maintain the stability of plantation forests and improve their ecosystem service functions in arid and semi-arid areas.
基金the National Key Basic Research Support Foundation of China (No. G1999043407), the KnowledgeInnovation Project of the Chinese Academy of Sciences (Nos. KZCX1-SW-01-12 and KSCX2-1-07) and the NationalNatural Science Foundation of China (No. 40231018).
文摘Based on data from a field survey in 2001 along the Northeast China transect (NECT), a precipitation gradient,and a short-term simulation experiment under ambient CO2 of 350 μmol mol-1 and doubled CO2 of 700 μmol mol-1with different soil moisture contents of 30%-45%, 45%-60%, and 60%-80% soil water holding capacity, the distributionof soil organic carbon and labile carbon along the NECT, their relationships with precipitation and their responses toCO2 enrichment and soil moisture changes were analyzed. The results indicated that the soil labile carbon along thegradient was significantly related to soil organic carbon (r = 0.993, P < 0.001). The soil labile carbon decreased morerapidly with depth than organic carbon. The soil organic and labile carbon along the gradient decreased with decrease inlongitude in both the topsoils and subsoils, and the coefficient of variation for the labile carbon was greater than that forthe organic carbon. Both the soil organic carbon and labile carbon had significant linear relationships with precipitation,with the correlation coefficient of soil organic carbon being lower (0.677 at P < 0.001) than that of soil labile carbon(0.712 at P < 0.001). In the simulation experiment with doubled and ambient CO2 and different moisture contents, thecoefficient of variation for soil organic carbon was only 1.3%, while for soil labile carbon it was 29.7%. With doubled CO2concentration (700 μmol mol-1), soil labile carbon decreased significantly at 45% to 60% of soil moisture content. Theseindicated that soil labile carbon was relatively more sensitive to environmental changes than soil organic carbon.
基金This work was financially supported by the National Key Research and Development Program of China(2016YFC0501001)the Key Laboratory Cooperative Research Project of Chinese Academy of Sciences.
文摘Bacteria in desert soil have unique phylogeny and important ecological functions, and theirresponses to changes in precipitation need further attention. However, relevant studies have mainlyfocused on the surface soil, and studies on the responses of bacteria at different soil depths to variationsin precipitation are rare. Thus, we used 16S rDNA high-throughput sequencing to investigate the changesin soil bacterial distribution along a mean annual precipitation gradient (50–150 mm) in the Alxa Desert,China, and compared the variation characteristics in the surface soil layer (0–10 cm) and subsurface soillayer (10–20 cm). Results showed that soil bacterial communities significantly changed along theprecipitation gradient in both soil layers. However, the subsurface soil layer could support bacterialcommunities with higher diversity and closer internal relationships but more internal competition than thesurface soil layer. Additionally, compared with the surface soil layer, variations in diversity andco-occurrence patterns in the subsurface soil layer were more in line with the changes in the mean annualprecipitation, while bacterial community structure was less variable in the subsurface soil layer. Comparedwith the mean annual precipitation, soil moisture had little influence on the structure and diversity of soilbacterial community but had a high correlation with intercommunity connectivity. Therefore, soilmoisture might play a complex role in mediating environmental conditions and soil bacterial communitycharacteristics. Due to the different responses of surface and subsurface soil bacteria to the changes inprecipitation, it is necessary to distinguish different soil layers when predicting the trends in desert soilbacterial conditions associated with precipitation, and prediction of subsurface soil bacteria may be moreaccurate.
基金supported by the National Basic resource survey (2017FY100200)Natural Science Foundation of China subsidization project (41471435)the West Light Program for Talent Cultivation of the Chinese Academy of Sciences。
文摘Nebkhas, discrete mounds of sand and vegetation, are a common landscape feature critical to the stability of desert ecosystems and supported by limited precipitation. Nebkha morphology and spatial pattern vary in landscapes, but it is unclear how they change along precipitation gradients in arid and semi-arid regions. In this study we determined morphology and soil nutrient patterns of nebkha from different regions of northwestern China. The objective of this study was to understand zonal differences among nebkhas and how morphological characteristics and soil nutrient patterns of nebkha change along a precipitation gradient in northwestern China. Our results shows that mean annual precipitation(MAP) had significant effects on morphological characteristics of nebkhas such as height, area, and volume which significantly decreased with an increase in MAP. MAP had significant positive effects on shrub cover and species richness of nebkha. Soil nutrients such as soil organic matter(SOM), total carbon(TC), total nitrogen(TN), and total phosphorus(TP) in the 0-10 cm layer increased with an increase of MAP, and soil nutrient content within nebkhas was higher than in inter-nebkha areas.We concluded that nebkhas are "fertile islands" with an important role in ecosystem dynamics in study regions. Further,MAP is a key factor which determined zonal differences, morphological, and soil nutrients patterns of nebkhas. However,disturbance, such as animal grazing, and planted sand-stabilizing vegetation accelerated the degeneration of nebkha landscapes. We recommend implementation of protective measures for nebkhas in arid and semi-arid areas of China.
基金National Program on Key Basic Research Project "973" Program (2009CB421502)R&D Special Fund for Public Welfare Industry (Meteorology) (GYHY201206005)+1 种基金Natural Science Foundation of China (40730948,40921160381,41175087,40830958,40905029,40875039)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This study introduces a new dynamical quantity, shear gradient vorticity (SGV), which is defined as vertical wind shear multiplying the horizontal component of vorticity gradient, aiming to diagnose heavy precipitation induced by some strong convective weather systems. The vorticity gradient component can be used to study the collision or merging process between different vortexes or the deformation of a vortex with a sharp vorticity gradient. Vertical wind shear, another contributed component of SGV, always represents the environmental dynamical factor in meteorology. By the combined effect of the two components, overall, SGV can represent the interaction between the environmental wind shear and the evolution of vortexes with a large vorticity gradient. Other traditional vorticity-like dynamical quantities (such as helicity) have the limitation in the diagnosis of the convection, since they do not consider the vorticity gradient. From this perspective, SGV has the potential to diagnose some strong convective weather processes, such as Extratropical Transition (ET) of tropical cyclones and the evolution of multicell storms. The forecast performance of SGV for the numerical ET case of Typhoon Toraji (0108) has been evaluated. Compared with helicity, SGV has shown a greater advantage to forecast the distribution of heavy precipitation more accurately, especially in the frontal zone.
基金jointly funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20020401)the Young Foundation of Institute of Mountain Hazard and Environment(SDS-QN-1702)National Natural Science Foundation of China(Grant No.41571205)
文摘The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are still controversial. We selected 717 grassland sites with ANPP and mean annual precipitation(MAP) data from 40 publications to characterize the relationships ANPP–MAP and PUE–MAP across different grassland types. The MAP and ANPP showed large variations across all grassland types, ranging from 69 to 2335 mm and 4.3 to 1706 g m^(-2), respectively. The global maximum PUE ranged from 0.19 to 1.49 g m^(-2) mm^(-1) with a unimodal pattern. Analysis using the sigmoid function explained the ANPP–MAP relationship best at the global scale. The gradient of the ANPP–MAP graph was small for arid and semi-arid sites(MAP <400 mm). This study improves our understanding of the relationship between ANPP and MAP across dry grassland ecosystems. It provides new perspectives on the prediction and modeling of variations in the ANPP for different grassland types along precipitation gradients.
基金supported by the National Natural Science Foundation of China (41761043, 41201196)the Youth Teacher Scientific Capability Promoting Project of Northwest Normal University, China (NWNU-LKQN2020-06, NWNU-LKQN-17-7)the Key Research and Development Program of Gansu Province, China (20YF3FA042)
文摘Variations of precipitation have great impacts on soil carbon cycle and decomposition of soil organic matter.Soil bacteria are crucial participants in regulating these ecological processes and vulnerable to altered precipitation.Studying the impacts of altered precipitation on soil bacterial community structure can provide a novel insight into the potential impacts of altered precipitation on soil carbon cycle and carbon storage of grassland.Therefore,soil bacterial community structure under a precipitation manipulation experiment was researched in a semi-arid desert grassland in Chinese Loess Plateau.Five precipitation levels,i.e.,control,reduced and increased precipitation by 40%and 20%,respectively(referred here as CK,DP40,DP20,IP40,and IP20)were set.The results showed that soil bacterial alpha diversity and rare bacteria significantly changed with altered precipitation,but the dominant bacteria and soil bacterial beta diversity did not change,which may be ascribed to the ecological strategy of soil bacteria.The linear discriminate analysis(LDA)effect size(LEfSe)method found that major response patterns of soil bacteria to altered precipitation were resource-limited and drought-tolerant populations.In addition,increasing precipitation greatly promoted inter-species competition,while decreasing precipitation highly facilitated inter-species cooperation.These changes in species interaction can promote different distribution ratios of bacterial populations under different precipitation conditions.In structural equation model(SEM)analysis,with changes in precipitation,plant growth characteristics were found to be drivers of soil bacterial community composition,while soil properties were not.In conclusion,our results indicated that in desert grassland ecosystem,the sensitive of soil rare bacteria to altered precipitation was stronger than that of dominant taxa,which may be related to the ecological strategy of bacteria,species interaction,and precipitation-induced variations of plant growth characteristics.
文摘Northeast China Transect(NECT),one of the fifteen International Biosphere-Geosphere Programme(IGBP)terrestrial transects,has been established for 10 years by Prof.Zhang Xin-Shi,through a core project of the IGBP--the Global Change and Terrestrial Ecosystems(GCTE).This transect is located in the mid-latitude semi-arid region,ranging 42–46°N latitude and 110–132°E longitude.The primary driving force for global change is precipitation and the secondary one is land use intensity.Research progresses have been performed during the past decade in the following aspects:ecological database development,climate and its variability,ecophysiological response of plants to environments,vegetation and landscape changes,biodiversity patterns and their changes,plant functional types and traits with relation to climatic gradient,productivity and carbon dynamics,pollen-vegetation relationship,trace gas emissions,land use and land cover changes,as well as biogeographical and biogeochemical modelling.In order to achieve the higher level of integrated research,the NECT needs the consistent basic data sets within the same framework,further field experiments and observations,integrated simulations of vegetation structure,process and function from patch,landscape to biome scales,intercomparisons ofresults and simulations within the transect and to other IGBP transects,multidisciplinary research,national and international co-ordinates,and full scientific plan and implementation strategy.
基金supported by the Qinghai Lake wetland ecosystem national field observation station capacity preliminary preparation projectQinghai Province Innovation Platform Construction Special Qinghai Province Key Laboratory of Physical Geography and Environmental Process[2020-ZJ-Y06]the National Natural Science Foundation of China(Nos.42161144003 and 42130506)
文摘Background Changes in precipitation patterns crucially impact soil microbial communities,and the ecosystem in Qinghai-Tibet Plateau(QTP)is highly vulnerable to climate change.However,we do not fully understand how soil microbial communities in the source wetlands of QTP respond to changes in precipitation.In this study,we employed advanced techniques such as high-throughput sequencing and metabolomics to investigate how soil microbial communities in a source wetland of Qinghai Lake respond to changes in precipitation after quadrennial precipitation treatment.Results Our findings showed that the predominant microbiota in the source wetland was Proteobacteria.Interestingly,alterations in precipitation levels,whether increased or reduced,did not significantly impact the diversity or functional groups of the microbial community.However,the structure of the microbial community did respond notably to changes in precipitation,leading to shifts in the relative abundance of Spirochaetes and Treponema.A notable finding was that reduced precipitation levels(–25%and-50%)and mild increases in precipitation(25%)within the region contributed to increased soil carbon content.However,this effect ceased to manifest when precipitation increased by 50%.Additionally,the reduction in precipitation prompted the release of soil metabolites like syringic acid and aldosterone,while enhanced precipitation resulted in a decrease in aldosterone content.Conclusions Precipitation changes altered the relative abundance of soil microbial communities and metabolites,which was conducive to increasing carbon storage in this alpine wetland.
基金National Natural Science Foundation of China(41271118)One-Three-Five Strategic Planning Project of Science and Technology,Chinese Academy of Sciences.
文摘Aims Both dominance distribution of species and the composition of the dominant species determine the distribution of traits within community.Leaf carbon(C)and nitrogen(N)isotopic composition are important leaf traits,and such traits of dominant species are associated with ecosystem C,water and N cycling.Very little is known how dominant species with distinct traits(e.g.N-fixing leguminous and non-leguminous trees)mediate resource utilization of the ecosystems in stressful environment.Methods Leaves of 81 dominant leguminous and non-leguminous trees were collected in forest(moist semi-deciduous and dry semi-deciduous ecosystems)and savanna(costal savanna,Guinean savanna and west Sudanian savanna ecosystems)areas and the transitional zone(between the forest and the savanna)along the transect from the south to the north of Ghana.We measured leaf traits,i.e.leafδ13C,leafδ15N,leaf water content,leaf mass per area(LMA)and C and N concentration.Correlation analyses were used to examine trait–trait relationships,and relationships of leaf traits with temperature and precipitation.We used analysis of covariance to test the differences in slopes of the linear regressions between legumes and non-legumes.Important Findings Leafδ13C,δ15N,leaf water content and LMA did not differ between leguminous and non-leguminous trees.Leaf N concentration and C:N ratio differed between the two groups.Moreover,leaf traits varied significantly among the six ecosystems.δ13C values were negatively correlated with annual precipitation and positively correlated with mean annual temperature.In contrast,leafδ15N of non-leguminous trees were positively correlated with annual precipitation and negatively correlated with mean annual temperature.For leguminous trees,such correlations were not significant.We also found significant coordination between leaf traits.However,the slopes of the linear relationships were significantly different between leguminous and non-leguminous trees.Our results indicate that shifts in dominant trees with distinct water-use efficiency were corresponded to the rainfall gradient.Moreover,leguminous trees,those characterized with relative high water-use efficiency in the low rainfall ecosystems,were also corresponded to the relative high N use efficiency.The high proportion of leguminous trees in the savannas is crucial to mitigate nutrient stress.
基金supported by the National Key R&D Program of China(2023YFF1304304)the National Natural Science Foundation of China(U20A2008)+1 种基金the Project of Grassland Multifunctionality Evaluation in Three-River-Source National Park(QHQXD–2023–28)the Fundamental Research Funds for the Central Universities,Southwest Minzu University(ZYN2023072).
文摘Plant roots show flexible traits to changing precipitation,but the factors driving root trait covariation remain poorly understood.This study investigated six key root traits and explored the potential driving factors,including plant community characteristics and soil properties,in the Zoige alpine meadow across five precipitation gradients:natural precipitation(1.0P),a 50%increasing precipitation(1.5P),and 30%,50%and 90%decreasing precipitation(0.7P,0.5P and 0.1P,respectively).Our results demonstrated distinct root trait responses to changes in precipitation.Both increasing(1.5P)and decreasing precipitation(0.1P,0.5P and 0.7P)inhibited root diameter(RD),specific root length(SRL)and specific root area compared with 1.0P.Conversely,root tissue density and root nitrogen content increased under decreasing precipitation but declined under 1.5P.With increasing precipitation,root foraging strategies shifted with thinner RD and larger SRL to that with a larger diameter.Shifts in root strategies were primarily influenced by soil properties,specifically soil water content and available nitrogen.Additionally,root strategies in surface soils(0-10 cm)were mainly related to the grass and sedge coverage,whereas in deeper soils(10-20 cm)root strategies were related to overall plant community coverage and biomass.Our findings indicate that root trait variations and strategies in alpine meadows are co-driven by soil properties and plant communities in response to changing precipitation.
基金supported by the Key Science&Technology Special Program of Inner Mongolia(2021ZD0011-04)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA23080303)National Natural Science Foundation of China(41801230).
文摘The positive relationships between biodiversity and ecosystem productivity have been broadly recognized in aquatic and terrestrial ecosystems,such as grasslands.However,remotely sensed assessment of functional diversity(FD)and its relationships with productivity across large regions are less studied in grasslands.In this study,we first examined the potential of spectral retrieval of 13 leaf functional traits from a species spectra-trait library to complement field measurements across three types of grassland communities in the Xinlingol grassland located in northern China.We then pre-selected the key traits out of 13 functional traits from 1664 plant individuals of 112 species to calculate in-situ productivity-related FD,and explored the multi-scale relationships of single-trait community weighed mean(CWM)and FD index(Rao’s quadratic entropy,RaoQ)with ecosystem productivity at plot level(1 m×1 m)and site level(30 m×30 m),respectively.Finally,we applied Sentinel-2 satellite data to infer regional FD through statistical relationships with direct spectral association using partial least squares regression(PLSR).With the leaf spectral prediction(cross-validation R^(2) cv=0.48-0.81)and in-situ measurement,CWM of organic acid detergent fiber(ADF),phosphorus(P),specific leaf area(SLA),chlorophyll(Chl),lignin(Lig)and carbon(C)together with RaoQ of ADF,C,N,Chl,SLA,and calcium(Ca)were selected to explain changes in ecosystem productivity(80%)at the plot level,while CWM of Car,Chl,Lig,NDF,NSC,P,and SLA together with RaoQ of C,SLA and non-structural carbohydrates(NSC)were selected to indicate productivity(94%)at site level.Furthermore,we found the combination of single-trait CWM(60%)outperformed that of RaoQ(34%)in determining ecosystem productivity at the site level compared with their almost equal contributions at plot level.At the regional scale,Sentinel-2 data could be used to infer these selected single-trait CWM and RaoQ values(R^(2) cv=0.32-0.82)and biomass(R^(2) cv=0.76),except for CWM and RaoQ of C(R^(2) cv=0.12-0.18).This study underscores the potential of Sentinel-2 satellite with leaf spectral measurements to monitor grassland functional diversity,informing the linkages between functional diversity and ecosystem functioning at regional scale.
