In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal ...In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal individuals, the dicephalic snake has divided ventral scales under the necks of the bifurcated columns. The snout- vent length （SVL） and overall total length of the individual are shorter than those of normal snakes of the same age. Nevertheless, the counts of nine different scale types that are often used for classification are all within the ranges of normal individuals. As far as we know, this is the first detailed morphological description of a dicephalic E. dione in the scientific literature.展开更多
Predictive assessments of the geomorphological systems’ behavior under climate warming in southern Siberia have been performed based on time-series data, using theoretical and empirical models of processes. High sens...Predictive assessments of the geomorphological systems’ behavior under climate warming in southern Siberia have been performed based on time-series data, using theoretical and empirical models of processes. High sensitivity and fast response of erosional, aeolian, and cryogenic processes to current climatic changes are presented. The current trends under changing functioning conditions of geomorphological systems while maintaining climatic trends have been determined. Areas with different targeting of morpholithogenesis are identified.展开更多
Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effiuxes from soil of a semiarid Aneurolepidium chinense steppe and a ...Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effiuxes from soil of a semiarid Aneurolepidium chinense steppe and a Stipa krylovii steppe in the Xilin River Basin of Inner Mongolia, China from March 2002 to December 2004. The results indicated that the soil respiration rates of the semiarid Aneurolepidium chinense steppe and the Stipa krylovii steppe were both relatively high from mid-May to mid-September of each year and remained low during the rest of the year. The minimum value of soil respiration occurred in December or January and negative effiuxes of CO2 appeared for several days during the non-growing season of individual years at the two sampling sites. A high annual variation was found in the two steppes with the coefficients of variance （CV） being over 94%, even high to 131%. The annual sums of soil CO2 effiux of the Aneurolepidium chinense steppe varied between 356.4 gC m^-2 yr^-1 and 408.8 gC m^-2 yr^-1, while those of the Stipa krylovii steppe in the three years were in the range of 110.6 gC m^-2 yr^-1 to 148.6 g Cm^-2 yr^-1. The mean respiration rates of the Aneurolepidium chinense steppe were significantly higher than those of the Stipa krylovii steppe in different statistical periods with the exception of the non-growing season. About 59.9% and 80.6% of the soil respiration variations in both steppes for the whole sampling period were caused by the changes of temperature and soil water content. In the Aneurolepidium chinense steppe, the soil respiration rate has significant or extremely significant positive correlation （r = 0.58 - 0.85, p 〈 0.05 or p 〈 0.01） with air temperature and ground temperature of the topsoil except in 2002; the unique contributions of temperature change to the soil respiration variation of the three years were 53.3%, 81.0% and 58.6%, respectively. But, for the Stipa krylovii steppe in the same time interval, the soil water content （especially that of the 10-20 cm layer） has a greater effect on the change of soil respiration, and the unique contributions of the change of the 10-20 cm soil water content to the variations of soil respiration in 2002 and 2003 were 60.0% and 54.3%, respectively. In 2004, in spite of the higher contribution of temperature than soil water content, the contribution of ground temperature at a depth of 10 cm was only 46.2%, much weaker than that of any single year in the Aneurolepidium chinense steppe.展开更多
Using the NDVI ratio method, the authors extracted phenological parameters from NOAA-AVHRR NDVI time-series data （1982-2008）. The start of the growing season （SOS） and the date of maximum NDVI （Peak-t） correlate...Using the NDVI ratio method, the authors extracted phenological parameters from NOAA-AVHRR NDVI time-series data （1982-2008）. The start of the growing season （SOS） and the date of maximum NDVI （Peak-t） correlated significantly with the mean annual precipitation along regional gradients of the steppes. Along the south transect （located at a lower latitude with a higher annual mean temperature） there was a positive correlation between the end of the growing season （EOS） and the mean annual precipitation along precipitation gradients （R2 = 0.709, p 〈 0.0001）. However, along the north transect （located at higher latitude with lower annual mean temperature）, the EOS was slightly negatively related with the mean annual precipitation （R2 = 0.179, p 〈 0.1）. There was positive correlation between the length of the growing season and the annual precipitation along two transects （R2 = 0.876, p 〈 0.0001 for the south transect; R2 = 0.290, p 〈 0.01 for the north transect）. Thus, for the Inner Mongolian steppe, it is precipitation rather than temperature that determines the date of the SOS.展开更多
In order to study the diurnal variation of soil CO2 effiux from temperate meadow steppes in Northeast China, and determine the best time for observation, a field experiment was conducted with a LI-6400 soil CO2 flux s...In order to study the diurnal variation of soil CO2 effiux from temperate meadow steppes in Northeast China, and determine the best time for observation, a field experiment was conducted with a LI-6400 soil CO2 flux system under five typical plant communi- ties （Suaeda glauca （Sg）, Chloris virgata （Cv）, Puecinellia distans （Pd）, Leymus chinensis （Lc） and Phragmites australis （Pa）） and an alkali-spot land （As） at the meadow steppe of western Songnen Plain. The results showed that the diurnal variation of soil CO2 effiux exhibited a single peak curve in the growing season. Diurnal maximum soil respiration （Rs） often appeared between 1 1：00 and 13：00, while the minimum occurred at 21：00-23：00 or before dawn. Air temperature near the soil surface （Ta） and soil temperature at 10 cm depth （Tlo） exerted dominant control on the diurnal variations of soil respiration. The time-windows 7：00-9：00 could be used as the optimal measuring time to represent the daily mean soil CO2 effiux at the Cv, Pd, Lc and Pa sites. The daily mean soil CO2 effiux was close to the soil COz effiux from 15：00 to 17：00 and the mean of 2 individual soil CO2 effiux from 15：00 to 19：00 at the As and Sg sites, respectively. During nocturnal hours, negative soil CO2 fluxes （CO2 downwards into the soil） were frequently observed at the As and Sg sites, the magnitude of the negative CO2 fluxes were 0.10-1.55 gmol/（m2.s） and 0.10-0.69 gmol/（m2.s）at the two sites. The results im- plied that alkaline soils could absorb CO2 under natural condition, which might have significant implications to the global carbon budget accounting.展开更多
To establish an assessment of floristic and edaphic characteristics of steppe formations we conducted a phytoecological study on a local scale by comparing the current plant diversity and soil in three (3) stations re...To establish an assessment of floristic and edaphic characteristics of steppe formations we conducted a phytoecological study on a local scale by comparing the current plant diversity and soil in three (3) stations representative of the vegetation to alfa (Stipa tenacissima L.) located south of Saida (western Algeria). The relations between the station, the vegetation and the characteristics of soils in the steppe are very imperfectly known. This study intends to analyze the relationship between floristic composition and edaphic parameters of the steppe at alfa. Anthropogenic pressures on plant structure are different imbalance resulting in one ecological. The floristic and edaphic data have been the subject of a factorial correspondence analysis (A.F.C). The floristic inventory denotes a regressive dynamics of the formations at alfa passing from one site to another. Thus 39 plant species have been inventoried in the site in good condition, against 26 species for the moderately degraded site and 16 species only for the damaged site. The coupled results between species and edaphic parameters show the relations between the plant diversity and the physico-chemical characteristics of the soils. The statistical analyses do appear a strong correlation between floristic composition, the state of vegetation and the edaphic parameters.展开更多
This work is an evaluation of the plant diversity of the white Wormwood formations (Artemisia herba-alba Asso.) in the steppes rangelands of the south-eastern zone of Sa?da (municipality of Maamora, Western Algeria). ...This work is an evaluation of the plant diversity of the white Wormwood formations (Artemisia herba-alba Asso.) in the steppes rangelands of the south-eastern zone of Sa?da (municipality of Maamora, Western Algeria). For this purpose, twenty-one phytoecological statements are carried out on three sample stations: an exclosure station where the white Wormwood is well developed and two other stations not protected where in one, the white Wormwood is moderately degraded and in the other one, it is strongly degraded. The factorial correspondences analysis (FCA) and the ascending hierarchical clustering (AHC) carried out on the floristic and edaphic parameters measured on these stations led to a hierarchy of the ecological factors determining the diversity of the studied plant formations with white Wormwood. The vegetation studied is marked by the dominance of the therophytes, particularly in the third station (very degraded station), while the exclosure station is essentially characterized by a high recovery rate and an important phytomass.展开更多
The connection between climatic factors and grazing is essential for maintaining ecosystem function and vegetation productivity.This study examined the impact of grazing intensity on vegetation across a broad climatic...The connection between climatic factors and grazing is essential for maintaining ecosystem function and vegetation productivity.This study examined the impact of grazing intensity on vegetation across a broad climatic gradient spanning the Espinal,Argentine Low Monte,and Patagonian Steppe ecoregions of Argentina.The research was carried out at eight sampling sites with radial grazing gradients generated around artificial water sources(piospheres),exhibiting two contrasting response patterns of vegetation to grazing pressure.One of the response patterns shows a typical vegetation response to grazing that the vegetation productivity increases with the distance to the water sources(decreasing grazing intensity).The second pattern is found in drier regions,where vegetation presents an inverse productivity response that vegetation productivity is higher near water sources(high grazing intensity)due to increased shrub cover.Vegetation productivity was measured using the Normalized Difference Vegetation Index(NDVI).Vegetation patch structure and cover were determined for each site with high,medium,and low grazing intensities.Results indicated that shrub cover is the primary driver of vegetation productivity,showing contrasting responses to grazing intensity between the two identified patterns.While NDVI proved to be a reliable proxy for shrub cover and total vegetation cover(R2>0.70),it failed to reflect grass cover dynamics.Furthermore,mean annual temperature was more strongly correlated with vegetation cover changes,while grazing intensity significantly altered vegetation patch structure and soil cover distribution.Specifically,in drier regions,high grazing intensity led to larger patches while,in wetter regions,it led to smaller patches(fragmentation).Shrubs,with their deeper roots and drought tolerance,were less preferred and more resistant to grazing in arid environments and thrived under grazing pressure in these arid conditions.Our results underscored the need for adaptive management strategies in grazing systems.Traditional approaches may require significant adjustments,as the efficacy of management hinges on the interplay of specific climatic conditions and the varied responses of vegetation.Furthermore,effective conservation efforts should prioritize the recognition and protection of shrubs given their critical contribution to ecosystem function and biodiversity.Ultimately,this research provides a valuable framework to understand the complex dynamics between grazing and vegetation in arid and semi-arid environments,highlighting that sustainable grazing practices should be tailored to account for both climatic variables and the unique characteristics of different plant communities.展开更多
Belowground bud banks are essential for the regeneration of plant population in arid desert areas,and their response to environmental changes could reflect adaptive strategies of plants to desert habitats.However,the ...Belowground bud banks are essential for the regeneration of plant population in arid desert areas,and their response to environmental changes could reflect adaptive strategies of plants to desert habitats.However,the size and composition of belowground bud banks and their response to environmental factors in the desert steppe zone remain poorly understood,challenging desertification control efforts in arid desert areas.This study examined the density and vertical distribution of horizontal and vertical rhizome buds of a rhizomatous legume herb Sophora alopecuroides L.,its population characteristics,and soil physical-chemical properties in three habitats(interdune lowland(IL),flat sandy land(FSL),and desert steppe(DS))in a desert steppe zone,northern China.Our findings revealed that:(1)total and horizontal rhizome bud densities of S.alopecuroides differed significantly among the three habitats(P<0.05),with the largest total rhizome bud density(177 buds/m2)in IL and the smallest(63 buds/m2)in DS;(2)horizontal rhizome buds distributed in the deep soil layer were dominant in IL,while vertical rhizome buds in the top soil layer were predominant in DS;and(3)soil coarse sand,nutrient content,and population density were the primary factors affecting bud bank density of S.alopecuroides.Specifically,horizontal rhizome buds were dependent largely on soil coarse sand content,and vertical rhizome buds tended to be more related to soil organic matter content and population density.Our results indicated that horizontal rhizome buds were more important in IL with frequent aeolian disturbance,whereas vertical rhizome buds were more important in DS with abundant water and nutrient resources.The plastic responses and survival strategies of S.alopecuroides bud bank to different habitats provide valuable information for the effective implementation of desertification control measures and the management of desert steppe ecosystems.展开更多
Grassland is the largest terrestrial ecosystem in China. It is of great significance to measure accurately the soil respiration of different grassland types for the contribution evaluation of the Chinese terrestrial e...Grassland is the largest terrestrial ecosystem in China. It is of great significance to measure accurately the soil respiration of different grassland types for the contribution evaluation of the Chinese terrestrial ecosystem’s carbon emission to the atmospheric CO2 concentration. A three-year (2005-2007) field experiment was carried out on three steppes of Stipa L. in the Xilin River Basin, Inner Mongolia, China, using a static opaque chamber technique. The seasonal and interannual variations of soil respiration rates were analyzed, and the annual total soil respiration of the three steppes was estimated. The numerical models between soil respiration and water-heat factors were established respectively. Similar seasonal dynamic and high annual and interannual variations of soil respiration were found in all of the three steppes. In the growing season, the fluctuation of soil respiration was particularly evident. The coefficients of variation (CVs) for soil respiration in different growing seasons ranged from 54% to 93%, and the annual CVs were all above 115%. The interannual CV of soil respiration progressively decreased in the order of Stipa grandis (S. grandis) steppe 】 Stipa baicalensis (S. baicalensis) steppe 】 Stipa krylovii (S. krylovii) steppe. The annual total soil respiration for the S. baicalensis steppe was 223.62?299.24 gC m-2 a-1, 150.62-226.99 gC m-2 a-1 for the S. grandis steppe, and 111.31–131.55 gC m-2 a-1 for the S. krylovii steppe, which were consistent with the precipitation gradient. The variation in the best fitting temperature factor explained the 63.5%, 73.0%, and 73.2% change in soil respiration in the three steppes at an annual time scale, and the corresponding Q10 values were 2.16, 2.98, and 2.40, respectively. Moreover, the Q10 values that were calculated by soil temperature at different depths all expressed a 10 cm 】 5 cm 】 surface in the three sampling sites. In the growing season, the soil respiration rates were related mostly to the surface soil moisture, and the 95.2%, 97.4%, and 93.2% variations in soil respiration in the three steppes were explained by the change in soil moisture at a depth of 0-10 cm, respectively.展开更多
Aims As a unique geographical unit of the earth,the tibetan Plateau is extensively covered by various Stipa communities.However,their vegetation features have not been reported systematically till now,especially in so...Aims As a unique geographical unit of the earth,the tibetan Plateau is extensively covered by various Stipa communities.However,their vegetation features have not been reported systematically till now,especially in some scantily explored regions.In this study,we endeavor to reveal the community types,quantitative charac-teristics and climatic distribution patterns of Stipa steppes in these areas based on primary relevés obtained from fieldwork.Methods We collected a total of 223 plots in 79 study sites in the Changthang Plateau and the Yarlung Zangbo Valley,ranging from 79°E to 91°E.the categories of Stipa formations were identified according to the classification scheme in Vegetation of China and then verified by Nonmetric Multidimensional Scaling.We performed detrended correspondence analysis and detrended canonical correspondence analysis to hunt for the alteration of Stipa communities along the precipitation gradient.Quantitative characteristics including species richness,coverage,biomass as well as importance values(IV)of dominant species were calcu-lated and visualized,respectively.Important Findings Stipa steppes in scantily explored regions of the tibetan Plateau are classified into 11 formations but major formations are rather limited in number.Formation(form.)Stipa purpurea is the most widespread Stipa assemblages not only in scantily explored regions but also across the whole tibetan Plateau.the characteristics of Stipa com-munities,including coverage,species richness,productivity and IV of dominant species,demonstrate the features of typical alpine steppes on the tibetan Plateau.Precipitation proves to be the prime climatic factor controlling the distribution patterns of Stipa assemblages.Form.Stipa subsessiliflora var.basiplumosa and form.Stipa glareosa normally distribute in arid habitats,but rainfall for the former is of greater variance.Form.Stipa roborowskyi and form.Stipa capillacea favor moderately moist environment.Form.Stipa purpurea and form.Stipa roborowskyi can tolerate a fairly broad range of precipitation.展开更多
Aims Extreme climate events have become more severe and frequent with global change in recent years.The Chinese temperate steppes are an important component of the Eurasian steppes and highly sensitive and vulnerable ...Aims Extreme climate events have become more severe and frequent with global change in recent years.The Chinese temperate steppes are an important component of the Eurasian steppes and highly sensitive and vulnerable to climatic change.As a result,the occur-rence of extreme climate events must have strong impacts on the temperate steppes.Therefore,understanding the spatio-temporal trends in extreme climate is important for us to assess the sensitivity and vulnerability of Chinese temperate steppes to climatic changes.This research had two specific objects to(i)specify the temporal changes in extreme climate events across the whole steppe and(ii)compare the trend differences for extreme climate events in differ-ent types of steppes-meadow steppe,typical steppe and desert steppe.Methods To investigate extreme climate trends in the temperate steppes of China,82 meteorological stations with daily temperature and precipi-tation data(1961-2013)were used.Meanwhile,eight core extreme climate indices(extreme high-temperature threshold,extreme low-temperature threshold,frost days,heatwave duration,heavy rain-fall threshold,percentage of heavy rainfall,heavy rainfall days and consecutive dry days)from the Statistical and Regional Dynamical Downscaling of Extremes for European Regions(STARDEX)project were selected to analyse the trends in extreme climate across the whole temperate steppe and the three main types(meadow steppe,typical steppe and desert steppe)through time and space.Important Findings The results showed that(i)the changes in extreme climatic tem-perature events across the whole temperate steppe were obvi-ous during 1961-2013.The frost days(−3.40 days/10 year[yr])decreased significantly,while the extreme high-temperature thresh-old(0.24℃/10 yr),extreme low-temperature threshold(0.52℃/10 yr),and heatwave duration(0.58 days/10 yr)increased notably.The annual changes in extreme precipitation were small and not sig-nificant.(ii)Differences appeared in the extreme climatic trends in different types of steppes.The desert steppe showed strong climate extremes and underwent the most significant asymmetric warming compared with the meadow steppe and typical steppe.At the same time,the heatwave duration(0.62 days/10 yr)increased.In terms of the extreme precipitation,there was no significant trend among the three types of steppes.However,the fluctuations in extreme precipi-tation were the largest in the desert steppe compared to those in the typical steppe and meadow steppe.展开更多
Aims Soil CO_(2) emission from steppes is affected by soil properties and vegetation in different successional stages.Primary and secondary succession of plants frequently occurred at the meadow steppe in Songnen Plai...Aims Soil CO_(2) emission from steppes is affected by soil properties and vegetation in different successional stages.Primary and secondary succession of plants frequently occurred at the meadow steppe in Songnen Plain,Northeast China,which indicates the large uncer-tainty associated with CO_(2) emission in this environment.This study aims to investigate the temporal variations of soil respiration(Rs)and the effect of plant succession on cumulative soil CO_(2) emission during the growing season.Methods Using a LI-6400 soil CO_(2) flux system,Rs of five vegetation types which represented different stages of plant succession in meadow steppes of Songnen Plain,China,was investigated during the grow-ing seasons of 2011 and 2012.Important Findings Soil temperature(Ts)was the dominant controlling factor of Rs,which could explain~64%of the change in CO_(2) fluxes.The Q10 values of Rs were ranged from 2.0 to 6.7,showing a decreasing trend with the plant successional stages.The cumulative CO_(2) emis-sion increased with the degree of vegetation succession and it aver-aged to 316±6 g C m^(−2)(ranges:74.8±6.7 to 516.5±11.4 g C m^(−2))during the growing season.The magnitude of soil CO_(2) emission during the growing season was positively correlated with above-ground plant biomass,soil organic carbon content and mean soil water content,while negatively linked to mean Ts,pH,electrical conductivity and exchangeable sodium percentages.The results implied that soil CO_(2) emission increased with the development of plant communities toward more advanced stages.Our findings pro-vided valuable information for understanding the variations of CO_(2) emission in the process of vegetation succession.展开更多
On the vast Hulun Buir steppe in north China’s Inner Mongolia Autonomous Region,grasslands stretch as far as the eye can see.Known as one of the world’s four great grasslands and celebrated as the“kingdom of flora ...On the vast Hulun Buir steppe in north China’s Inner Mongolia Autonomous Region,grasslands stretch as far as the eye can see.Known as one of the world’s four great grasslands and celebrated as the“kingdom of flora and fauna in north China,”the region has long been a cradle of traditional nomadic culture and a vital base for animal husbandry.展开更多
In mid-June,the vast,rolling meadow steppe grasslands of Bayanwenduer Sumu in Ar Horqin Banner,Inner Mongolia Autonomous Region,once again stretched into the horizon like green waves with herds of cattle and sheep sca...In mid-June,the vast,rolling meadow steppe grasslands of Bayanwenduer Sumu in Ar Horqin Banner,Inner Mongolia Autonomous Region,once again stretched into the horizon like green waves with herds of cattle and sheep scattered across them like pearls in a green ocean.This flock was driven by herders on horseback,motorcycles,and agricultural vehicles,leading the animals to summer pastures in one of the most important migrations of the year.展开更多
Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitat...Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitats by combining niche modeling with ecological trait analysis. We conducted standardized point surveys to examine the habitat preferences of 32 bird species in Inner Mongolia, China, and quantified their habitat niche parameters using the Outlying Mean Index (OMI). Our results reveal distinct habitat preferences among species, with some thriving in intact environments while others are better adapted to fragmented areas. Grassland species showed high specialization along the fragmentation gradient, while others exhibited adaptability to varying levels of fragmentation. Using a Generalized Additive Model (GAM), we identified three key traits influencing habitat occupancy: hand-wing index, body mass, and range size. Specifically, species with medium hand-wing indices, moderate body mass, and larger range sizes were more likely to occupy heavily fragmented habitats. These findings provide empirical evidence on how habitat fragmentation affects bird species in steppe ecosystems. The study highlights the importance of functional traits in understanding avian responses to habitat fragmentation and offers a foundation for developing effective conservation strategies to preserve biodiversity in fragmented landscapes.展开更多
Amid global precipitation changes,it remains unclear whether hydrological niche separation(HNS)mechanisms apply to herbaceous plant communities in desert steppes are severely affected by seasonal drought.How these pla...Amid global precipitation changes,it remains unclear whether hydrological niche separation(HNS)mechanisms apply to herbaceous plant communities in desert steppes are severely affected by seasonal drought.How these plants access limited water and tolerate drought to coexist also remains unverified.In this study,we employed stable isotope techniques to examine water acquisition and drought adaptation in coexisting species of the desert steppe in northern China under five precipitation treatments,i.e.,decreased 50%,decreased 30%,ambient,increased 30%,and increased 50%precipitation.The following results showed that:(1)water sources of coexisting species shifted with changes in precipitation amount and timing,i.e.,all coexisting plants exhibited preferential utilization of surface soil moisture.When surface soil moisture was scarce,they shifted to deeper water sources,and when deep water sources remained scarce,they were forced to compete more intensely for surface water sources;(2)community's HNS was affected by precipitation amount but not by timing,i.e.,with adequate soil moisture,plant water source ranges expanded,reducing overlap and enhancing HNS,whereas under extreme drought,the range contracted and increased the overlap,although HNS remained stable;and(3)water acquisition strategies of coexisting species differed along hydrological niche axis defined by water stress adaptability(i.e.,stable carbon isotope composition and proline content).Convolvulus ammannii Desr.had the strongest drought adaptation,although its strategy showed a weak correlation with water uptake.Stipa breviflora Griseb.,with moderate drought resistance,adopted a water-conserving strategy that was suitable for extreme drought.Leymus secalinus(Georgi)Tzvelev,Polygala tenuifolia Willd.,and Larix potaninii Batalin showed resource-dependent and flexible water strategies,thriving in wetter soils but struggling under extreme drought.Our findings indicated that herbaceous species in desert steppes adapted their water uptake and drought tolerance strategies according to changes in precipitation amount and timing.As a core regulatory mechanism,HNS(under increasing precipitation variability due to climate change)not only supports species coexistence by reducing interspecific competition,but also promotes efficient soil moisture use.This mechanism enhances community drought resistance and contributes to ecosystem stability.Overall,this study provides key ecological evidence for understanding plant community adaptation in arid and semi-arid areas facing the influence of global climate change.展开更多
Grasslands are among the world's most threatened ecosystems, and steppe birds face increasing risks from human activities. This study investigates how human impacts affect the distribution and community structure ...Grasslands are among the world's most threatened ecosystems, and steppe birds face increasing risks from human activities. This study investigates how human impacts affect the distribution and community structure of breeding steppe birds in Inner Mongolia, a biodiversity hotspot in Asia. We conducted standardized point-count surveys across a gradient from intact grasslands to urbanized areas, integrating species occurrence data, functional traits and the Human Footprint Index (HFI). Using Generalized Linear Models (GLMs) and Conditional Random Fields (CRFs), we assessed trait-environment interactions and shifts in species associations. Our results indicate that the HFI significantly affects bird communities. Habitat specialists, such as Mongolian Lark (Melanocorypha mongolica), showed negative responses, whereas generalists like Eurasian Tree Sparrow (Passer montanus) thrived in disturbed areas. Trait-based analysis showed that species with larger body mass and specialized diets were negatively associated with HFI, whereas those linked to human-modified habitats exhibiting strong positive associations. In areas with high human footprint, co-occurrence networks grew more polarized: specialists faced intensified competition, while species with positive HFI responses formed stronger positive associations. CRF models indicated that human activities restructure species interactions, favoring generalists and simplifying community dynamics. These findings highlight the dual role of human impact in supporting some species while threatening specialists, potentially driving biotic homogenization. Our study emphasizes the need for conservation strategies that protect vulnerable species and manage those that thrive in human-altered environments. By linking traits and interactions to human impacts, this study provides a framework for identifying at-risk species and guiding conservation in the Anthropocene.展开更多
Tibetan alpine steppes are large and sensitive terrestrial carbon(C)reservoirs that are experiencing desertification due to global change and overgrazing,which can lead to stronger resource limitations for both above-...Tibetan alpine steppes are large and sensitive terrestrial carbon(C)reservoirs that are experiencing desertification due to global change and overgrazing,which can lead to stronger resource limitations for both above-and belowground communities.Soil nutrients,especially nitrogen(N)and phosphorus(P),are the crucial resources for plant growth and microbial metabolism.However,whether both plant and soil microbial communities in the degraded alpine steppes are limited by these soil nutrients remains unclear,which limits our understanding of the mechanisms of desertification and subsequent ecosystem restoration.Here,we evaluated potential nutrient limitations of the plant and soil microbial communities in the alpine steppe across five stages of desertification using stoichiometry-based approaches.Our results showed that soil microbial metabolism was mainly limited by C and P,and the plant N limitation and microbial C limitation were intensified while the microbial P limitation was relieved during desertification.Plant-soil-microbe interactions had significant impacts on the microbial C and P limitations,explaining 72 and 61%of the variation,respectively.Specifically,desertification ultimately affected microbial metabolic limitations by regulating soil pH,soil nutrients,and the plant N limitation.Moreover,the microbial C limitation further reduced microbial C use efficiency(CUE)with desertification,which is detrimental for organic C retention in the degraded soil.Overall,this study revealed that microbial metabolic limitations through plant-microbe interactions were the key drivers affecting soil microbial CUE,and it provided insights that can advance our knowledge of the microbial regulation of nutrient cycles and C sequestration.展开更多
基金supported by 2013 Research Grant(C100983401-01) from Kangwon National University
文摘In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal individuals, the dicephalic snake has divided ventral scales under the necks of the bifurcated columns. The snout- vent length （SVL） and overall total length of the individual are shorter than those of normal snakes of the same age. Nevertheless, the counts of nine different scale types that are often used for classification are all within the ranges of normal individuals. As far as we know, this is the first detailed morphological description of a dicephalic E. dione in the scientific literature.
文摘Predictive assessments of the geomorphological systems’ behavior under climate warming in southern Siberia have been performed based on time-series data, using theoretical and empirical models of processes. High sensitivity and fast response of erosional, aeolian, and cryogenic processes to current climatic changes are presented. The current trends under changing functioning conditions of geomorphological systems while maintaining climatic trends have been determined. Areas with different targeting of morpholithogenesis are identified.
基金This work was jointly supported by the Knowledge Innovation Program of the Chinese Academy of Sciences （Grant No. KZCX1-SW-01-04） the National Natural Science Foundation of China （Grant No. 40501072） the project on the Carbon Cycle and Driving Mechanisms in the Chinese Terrestrial Ecosystem （Grant No. 2002CB412503）.
文摘Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effiuxes from soil of a semiarid Aneurolepidium chinense steppe and a Stipa krylovii steppe in the Xilin River Basin of Inner Mongolia, China from March 2002 to December 2004. The results indicated that the soil respiration rates of the semiarid Aneurolepidium chinense steppe and the Stipa krylovii steppe were both relatively high from mid-May to mid-September of each year and remained low during the rest of the year. The minimum value of soil respiration occurred in December or January and negative effiuxes of CO2 appeared for several days during the non-growing season of individual years at the two sampling sites. A high annual variation was found in the two steppes with the coefficients of variance （CV） being over 94%, even high to 131%. The annual sums of soil CO2 effiux of the Aneurolepidium chinense steppe varied between 356.4 gC m^-2 yr^-1 and 408.8 gC m^-2 yr^-1, while those of the Stipa krylovii steppe in the three years were in the range of 110.6 gC m^-2 yr^-1 to 148.6 g Cm^-2 yr^-1. The mean respiration rates of the Aneurolepidium chinense steppe were significantly higher than those of the Stipa krylovii steppe in different statistical periods with the exception of the non-growing season. About 59.9% and 80.6% of the soil respiration variations in both steppes for the whole sampling period were caused by the changes of temperature and soil water content. In the Aneurolepidium chinense steppe, the soil respiration rate has significant or extremely significant positive correlation （r = 0.58 - 0.85, p 〈 0.05 or p 〈 0.01） with air temperature and ground temperature of the topsoil except in 2002; the unique contributions of temperature change to the soil respiration variation of the three years were 53.3%, 81.0% and 58.6%, respectively. But, for the Stipa krylovii steppe in the same time interval, the soil water content （especially that of the 10-20 cm layer） has a greater effect on the change of soil respiration, and the unique contributions of the change of the 10-20 cm soil water content to the variations of soil respiration in 2002 and 2003 were 60.0% and 54.3%, respectively. In 2004, in spite of the higher contribution of temperature than soil water content, the contribution of ground temperature at a depth of 10 cm was only 46.2%, much weaker than that of any single year in the Aneurolepidium chinense steppe.
基金jointly supported by the National Basic Research Program of China[973 Program,2012CB956202]the Collaborative Innovation Center of Research and Development on Tibetan Characteristic Agricultural and Animal Husbandry Resources
文摘Using the NDVI ratio method, the authors extracted phenological parameters from NOAA-AVHRR NDVI time-series data （1982-2008）. The start of the growing season （SOS） and the date of maximum NDVI （Peak-t） correlated significantly with the mean annual precipitation along regional gradients of the steppes. Along the south transect （located at a lower latitude with a higher annual mean temperature） there was a positive correlation between the end of the growing season （EOS） and the mean annual precipitation along precipitation gradients （R2 = 0.709, p 〈 0.0001）. However, along the north transect （located at higher latitude with lower annual mean temperature）, the EOS was slightly negatively related with the mean annual precipitation （R2 = 0.179, p 〈 0.1）. There was positive correlation between the length of the growing season and the annual precipitation along two transects （R2 = 0.876, p 〈 0.0001 for the south transect; R2 = 0.290, p 〈 0.01 for the north transect）. Thus, for the Inner Mongolian steppe, it is precipitation rather than temperature that determines the date of the SOS.
基金Under the auspices of National Natural Science Foundation of China(No.41501090,41501105)Fundamental Research Funds for Central Universities(No.2412015KJ023)
文摘In order to study the diurnal variation of soil CO2 effiux from temperate meadow steppes in Northeast China, and determine the best time for observation, a field experiment was conducted with a LI-6400 soil CO2 flux system under five typical plant communi- ties （Suaeda glauca （Sg）, Chloris virgata （Cv）, Puecinellia distans （Pd）, Leymus chinensis （Lc） and Phragmites australis （Pa）） and an alkali-spot land （As） at the meadow steppe of western Songnen Plain. The results showed that the diurnal variation of soil CO2 effiux exhibited a single peak curve in the growing season. Diurnal maximum soil respiration （Rs） often appeared between 1 1：00 and 13：00, while the minimum occurred at 21：00-23：00 or before dawn. Air temperature near the soil surface （Ta） and soil temperature at 10 cm depth （Tlo） exerted dominant control on the diurnal variations of soil respiration. The time-windows 7：00-9：00 could be used as the optimal measuring time to represent the daily mean soil CO2 effiux at the Cv, Pd, Lc and Pa sites. The daily mean soil CO2 effiux was close to the soil COz effiux from 15：00 to 17：00 and the mean of 2 individual soil CO2 effiux from 15：00 to 19：00 at the As and Sg sites, respectively. During nocturnal hours, negative soil CO2 fluxes （CO2 downwards into the soil） were frequently observed at the As and Sg sites, the magnitude of the negative CO2 fluxes were 0.10-1.55 gmol/（m2.s） and 0.10-0.69 gmol/（m2.s）at the two sites. The results im- plied that alkaline soils could absorb CO2 under natural condition, which might have significant implications to the global carbon budget accounting.
文摘To establish an assessment of floristic and edaphic characteristics of steppe formations we conducted a phytoecological study on a local scale by comparing the current plant diversity and soil in three (3) stations representative of the vegetation to alfa (Stipa tenacissima L.) located south of Saida (western Algeria). The relations between the station, the vegetation and the characteristics of soils in the steppe are very imperfectly known. This study intends to analyze the relationship between floristic composition and edaphic parameters of the steppe at alfa. Anthropogenic pressures on plant structure are different imbalance resulting in one ecological. The floristic and edaphic data have been the subject of a factorial correspondence analysis (A.F.C). The floristic inventory denotes a regressive dynamics of the formations at alfa passing from one site to another. Thus 39 plant species have been inventoried in the site in good condition, against 26 species for the moderately degraded site and 16 species only for the damaged site. The coupled results between species and edaphic parameters show the relations between the plant diversity and the physico-chemical characteristics of the soils. The statistical analyses do appear a strong correlation between floristic composition, the state of vegetation and the edaphic parameters.
文摘This work is an evaluation of the plant diversity of the white Wormwood formations (Artemisia herba-alba Asso.) in the steppes rangelands of the south-eastern zone of Sa?da (municipality of Maamora, Western Algeria). For this purpose, twenty-one phytoecological statements are carried out on three sample stations: an exclosure station where the white Wormwood is well developed and two other stations not protected where in one, the white Wormwood is moderately degraded and in the other one, it is strongly degraded. The factorial correspondences analysis (FCA) and the ascending hierarchical clustering (AHC) carried out on the floristic and edaphic parameters measured on these stations led to a hierarchy of the ecological factors determining the diversity of the studied plant formations with white Wormwood. The vegetation studied is marked by the dominance of the therophytes, particularly in the third station (very degraded station), while the exclosure station is essentially characterized by a high recovery rate and an important phytomass.
基金supported by the Universidad Nacional de Río Negro(PI-UNRN 40C-1088)the Consejo Nacional de Investigaciones Científicas y Técnicas(PIP-CONICET 2023-402).
文摘The connection between climatic factors and grazing is essential for maintaining ecosystem function and vegetation productivity.This study examined the impact of grazing intensity on vegetation across a broad climatic gradient spanning the Espinal,Argentine Low Monte,and Patagonian Steppe ecoregions of Argentina.The research was carried out at eight sampling sites with radial grazing gradients generated around artificial water sources(piospheres),exhibiting two contrasting response patterns of vegetation to grazing pressure.One of the response patterns shows a typical vegetation response to grazing that the vegetation productivity increases with the distance to the water sources(decreasing grazing intensity).The second pattern is found in drier regions,where vegetation presents an inverse productivity response that vegetation productivity is higher near water sources(high grazing intensity)due to increased shrub cover.Vegetation productivity was measured using the Normalized Difference Vegetation Index(NDVI).Vegetation patch structure and cover were determined for each site with high,medium,and low grazing intensities.Results indicated that shrub cover is the primary driver of vegetation productivity,showing contrasting responses to grazing intensity between the two identified patterns.While NDVI proved to be a reliable proxy for shrub cover and total vegetation cover(R2>0.70),it failed to reflect grass cover dynamics.Furthermore,mean annual temperature was more strongly correlated with vegetation cover changes,while grazing intensity significantly altered vegetation patch structure and soil cover distribution.Specifically,in drier regions,high grazing intensity led to larger patches while,in wetter regions,it led to smaller patches(fragmentation).Shrubs,with their deeper roots and drought tolerance,were less preferred and more resistant to grazing in arid environments and thrived under grazing pressure in these arid conditions.Our results underscored the need for adaptive management strategies in grazing systems.Traditional approaches may require significant adjustments,as the efficacy of management hinges on the interplay of specific climatic conditions and the varied responses of vegetation.Furthermore,effective conservation efforts should prioritize the recognition and protection of shrubs given their critical contribution to ecosystem function and biodiversity.Ultimately,this research provides a valuable framework to understand the complex dynamics between grazing and vegetation in arid and semi-arid environments,highlighting that sustainable grazing practices should be tailored to account for both climatic variables and the unique characteristics of different plant communities.
基金funded by the National Natural Science Foundation of China(42207539,42377470)the Key Research and Development Project of Science and Technology Plan of Gansu Province in China International Science and Technology Cooperation Project(25YFWA009).
文摘Belowground bud banks are essential for the regeneration of plant population in arid desert areas,and their response to environmental changes could reflect adaptive strategies of plants to desert habitats.However,the size and composition of belowground bud banks and their response to environmental factors in the desert steppe zone remain poorly understood,challenging desertification control efforts in arid desert areas.This study examined the density and vertical distribution of horizontal and vertical rhizome buds of a rhizomatous legume herb Sophora alopecuroides L.,its population characteristics,and soil physical-chemical properties in three habitats(interdune lowland(IL),flat sandy land(FSL),and desert steppe(DS))in a desert steppe zone,northern China.Our findings revealed that:(1)total and horizontal rhizome bud densities of S.alopecuroides differed significantly among the three habitats(P<0.05),with the largest total rhizome bud density(177 buds/m2)in IL and the smallest(63 buds/m2)in DS;(2)horizontal rhizome buds distributed in the deep soil layer were dominant in IL,while vertical rhizome buds in the top soil layer were predominant in DS;and(3)soil coarse sand,nutrient content,and population density were the primary factors affecting bud bank density of S.alopecuroides.Specifically,horizontal rhizome buds were dependent largely on soil coarse sand content,and vertical rhizome buds tended to be more related to soil organic matter content and population density.Our results indicated that horizontal rhizome buds were more important in IL with frequent aeolian disturbance,whereas vertical rhizome buds were more important in DS with abundant water and nutrient resources.The plastic responses and survival strategies of S.alopecuroides bud bank to different habitats provide valuable information for the effective implementation of desertification control measures and the management of desert steppe ecosystems.
基金supported by National Natural Science Foundation of China (Grant Nos. 40730105, 40673067, and 40973057)National Key Technology Research and Development Program (Grant No. 2007BAC03A11)
文摘Grassland is the largest terrestrial ecosystem in China. It is of great significance to measure accurately the soil respiration of different grassland types for the contribution evaluation of the Chinese terrestrial ecosystem’s carbon emission to the atmospheric CO2 concentration. A three-year (2005-2007) field experiment was carried out on three steppes of Stipa L. in the Xilin River Basin, Inner Mongolia, China, using a static opaque chamber technique. The seasonal and interannual variations of soil respiration rates were analyzed, and the annual total soil respiration of the three steppes was estimated. The numerical models between soil respiration and water-heat factors were established respectively. Similar seasonal dynamic and high annual and interannual variations of soil respiration were found in all of the three steppes. In the growing season, the fluctuation of soil respiration was particularly evident. The coefficients of variation (CVs) for soil respiration in different growing seasons ranged from 54% to 93%, and the annual CVs were all above 115%. The interannual CV of soil respiration progressively decreased in the order of Stipa grandis (S. grandis) steppe 】 Stipa baicalensis (S. baicalensis) steppe 】 Stipa krylovii (S. krylovii) steppe. The annual total soil respiration for the S. baicalensis steppe was 223.62?299.24 gC m-2 a-1, 150.62-226.99 gC m-2 a-1 for the S. grandis steppe, and 111.31–131.55 gC m-2 a-1 for the S. krylovii steppe, which were consistent with the precipitation gradient. The variation in the best fitting temperature factor explained the 63.5%, 73.0%, and 73.2% change in soil respiration in the three steppes at an annual time scale, and the corresponding Q10 values were 2.16, 2.98, and 2.40, respectively. Moreover, the Q10 values that were calculated by soil temperature at different depths all expressed a 10 cm 】 5 cm 】 surface in the three sampling sites. In the growing season, the soil respiration rates were related mostly to the surface soil moisture, and the 95.2%, 97.4%, and 93.2% variations in soil respiration in the three steppes were explained by the change in soil moisture at a depth of 0-10 cm, respectively.
基金Key Program of National Fundamental Scientific Research funded by the Ministry of Science and Technology of China:Integrated Scientific Investigation in Data-deficient Regions of the Tibetan Plateau(2012FY111400)Redaction of Vegetation of China(2015FY210200).
文摘Aims As a unique geographical unit of the earth,the tibetan Plateau is extensively covered by various Stipa communities.However,their vegetation features have not been reported systematically till now,especially in some scantily explored regions.In this study,we endeavor to reveal the community types,quantitative charac-teristics and climatic distribution patterns of Stipa steppes in these areas based on primary relevés obtained from fieldwork.Methods We collected a total of 223 plots in 79 study sites in the Changthang Plateau and the Yarlung Zangbo Valley,ranging from 79°E to 91°E.the categories of Stipa formations were identified according to the classification scheme in Vegetation of China and then verified by Nonmetric Multidimensional Scaling.We performed detrended correspondence analysis and detrended canonical correspondence analysis to hunt for the alteration of Stipa communities along the precipitation gradient.Quantitative characteristics including species richness,coverage,biomass as well as importance values(IV)of dominant species were calcu-lated and visualized,respectively.Important Findings Stipa steppes in scantily explored regions of the tibetan Plateau are classified into 11 formations but major formations are rather limited in number.Formation(form.)Stipa purpurea is the most widespread Stipa assemblages not only in scantily explored regions but also across the whole tibetan Plateau.the characteristics of Stipa com-munities,including coverage,species richness,productivity and IV of dominant species,demonstrate the features of typical alpine steppes on the tibetan Plateau.Precipitation proves to be the prime climatic factor controlling the distribution patterns of Stipa assemblages.Form.Stipa subsessiliflora var.basiplumosa and form.Stipa glareosa normally distribute in arid habitats,but rainfall for the former is of greater variance.Form.Stipa roborowskyi and form.Stipa capillacea favor moderately moist environment.Form.Stipa purpurea and form.Stipa roborowskyi can tolerate a fairly broad range of precipitation.
基金National Natural Science Foundation of China(41775108)Agriculture to Climate Change(132020010406)Industry of National Public Welfare(Meteorological)Scientific Research(GYHY201406034).Conflict of interest.None declared.
文摘Aims Extreme climate events have become more severe and frequent with global change in recent years.The Chinese temperate steppes are an important component of the Eurasian steppes and highly sensitive and vulnerable to climatic change.As a result,the occur-rence of extreme climate events must have strong impacts on the temperate steppes.Therefore,understanding the spatio-temporal trends in extreme climate is important for us to assess the sensitivity and vulnerability of Chinese temperate steppes to climatic changes.This research had two specific objects to(i)specify the temporal changes in extreme climate events across the whole steppe and(ii)compare the trend differences for extreme climate events in differ-ent types of steppes-meadow steppe,typical steppe and desert steppe.Methods To investigate extreme climate trends in the temperate steppes of China,82 meteorological stations with daily temperature and precipi-tation data(1961-2013)were used.Meanwhile,eight core extreme climate indices(extreme high-temperature threshold,extreme low-temperature threshold,frost days,heatwave duration,heavy rain-fall threshold,percentage of heavy rainfall,heavy rainfall days and consecutive dry days)from the Statistical and Regional Dynamical Downscaling of Extremes for European Regions(STARDEX)project were selected to analyse the trends in extreme climate across the whole temperate steppe and the three main types(meadow steppe,typical steppe and desert steppe)through time and space.Important Findings The results showed that(i)the changes in extreme climatic tem-perature events across the whole temperate steppe were obvi-ous during 1961-2013.The frost days(−3.40 days/10 year[yr])decreased significantly,while the extreme high-temperature thresh-old(0.24℃/10 yr),extreme low-temperature threshold(0.52℃/10 yr),and heatwave duration(0.58 days/10 yr)increased notably.The annual changes in extreme precipitation were small and not sig-nificant.(ii)Differences appeared in the extreme climatic trends in different types of steppes.The desert steppe showed strong climate extremes and underwent the most significant asymmetric warming compared with the meadow steppe and typical steppe.At the same time,the heatwave duration(0.62 days/10 yr)increased.In terms of the extreme precipitation,there was no significant trend among the three types of steppes.However,the fluctuations in extreme precipi-tation were the largest in the desert steppe compared to those in the typical steppe and meadow steppe.
基金National Natural Science Foundation of China(31100403,41101207)Special Fund for Agro-scientific Research in the Public Interest,China(201303095-8).
文摘Aims Soil CO_(2) emission from steppes is affected by soil properties and vegetation in different successional stages.Primary and secondary succession of plants frequently occurred at the meadow steppe in Songnen Plain,Northeast China,which indicates the large uncer-tainty associated with CO_(2) emission in this environment.This study aims to investigate the temporal variations of soil respiration(Rs)and the effect of plant succession on cumulative soil CO_(2) emission during the growing season.Methods Using a LI-6400 soil CO_(2) flux system,Rs of five vegetation types which represented different stages of plant succession in meadow steppes of Songnen Plain,China,was investigated during the grow-ing seasons of 2011 and 2012.Important Findings Soil temperature(Ts)was the dominant controlling factor of Rs,which could explain~64%of the change in CO_(2) fluxes.The Q10 values of Rs were ranged from 2.0 to 6.7,showing a decreasing trend with the plant successional stages.The cumulative CO_(2) emis-sion increased with the degree of vegetation succession and it aver-aged to 316±6 g C m^(−2)(ranges:74.8±6.7 to 516.5±11.4 g C m^(−2))during the growing season.The magnitude of soil CO_(2) emission during the growing season was positively correlated with above-ground plant biomass,soil organic carbon content and mean soil water content,while negatively linked to mean Ts,pH,electrical conductivity and exchangeable sodium percentages.The results implied that soil CO_(2) emission increased with the development of plant communities toward more advanced stages.Our findings pro-vided valuable information for understanding the variations of CO_(2) emission in the process of vegetation succession.
文摘On the vast Hulun Buir steppe in north China’s Inner Mongolia Autonomous Region,grasslands stretch as far as the eye can see.Known as one of the world’s four great grasslands and celebrated as the“kingdom of flora and fauna in north China,”the region has long been a cradle of traditional nomadic culture and a vital base for animal husbandry.
文摘In mid-June,the vast,rolling meadow steppe grasslands of Bayanwenduer Sumu in Ar Horqin Banner,Inner Mongolia Autonomous Region,once again stretched into the horizon like green waves with herds of cattle and sheep scattered across them like pearls in a green ocean.This flock was driven by herders on horseback,motorcycles,and agricultural vehicles,leading the animals to summer pastures in one of the most important migrations of the year.
基金supported by the National Natural Science Foundation of China(No.32201304)the Fundamental Research Funds for the Central Universities(No.2412022QD026).
文摘Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitats by combining niche modeling with ecological trait analysis. We conducted standardized point surveys to examine the habitat preferences of 32 bird species in Inner Mongolia, China, and quantified their habitat niche parameters using the Outlying Mean Index (OMI). Our results reveal distinct habitat preferences among species, with some thriving in intact environments while others are better adapted to fragmented areas. Grassland species showed high specialization along the fragmentation gradient, while others exhibited adaptability to varying levels of fragmentation. Using a Generalized Additive Model (GAM), we identified three key traits influencing habitat occupancy: hand-wing index, body mass, and range size. Specifically, species with medium hand-wing indices, moderate body mass, and larger range sizes were more likely to occupy heavily fragmented habitats. These findings provide empirical evidence on how habitat fragmentation affects bird species in steppe ecosystems. The study highlights the importance of functional traits in understanding avian responses to habitat fragmentation and offers a foundation for developing effective conservation strategies to preserve biodiversity in fragmented landscapes.
基金funded by the National Natural Science Foundation of China(32160406).
文摘Amid global precipitation changes,it remains unclear whether hydrological niche separation(HNS)mechanisms apply to herbaceous plant communities in desert steppes are severely affected by seasonal drought.How these plants access limited water and tolerate drought to coexist also remains unverified.In this study,we employed stable isotope techniques to examine water acquisition and drought adaptation in coexisting species of the desert steppe in northern China under five precipitation treatments,i.e.,decreased 50%,decreased 30%,ambient,increased 30%,and increased 50%precipitation.The following results showed that:(1)water sources of coexisting species shifted with changes in precipitation amount and timing,i.e.,all coexisting plants exhibited preferential utilization of surface soil moisture.When surface soil moisture was scarce,they shifted to deeper water sources,and when deep water sources remained scarce,they were forced to compete more intensely for surface water sources;(2)community's HNS was affected by precipitation amount but not by timing,i.e.,with adequate soil moisture,plant water source ranges expanded,reducing overlap and enhancing HNS,whereas under extreme drought,the range contracted and increased the overlap,although HNS remained stable;and(3)water acquisition strategies of coexisting species differed along hydrological niche axis defined by water stress adaptability(i.e.,stable carbon isotope composition and proline content).Convolvulus ammannii Desr.had the strongest drought adaptation,although its strategy showed a weak correlation with water uptake.Stipa breviflora Griseb.,with moderate drought resistance,adopted a water-conserving strategy that was suitable for extreme drought.Leymus secalinus(Georgi)Tzvelev,Polygala tenuifolia Willd.,and Larix potaninii Batalin showed resource-dependent and flexible water strategies,thriving in wetter soils but struggling under extreme drought.Our findings indicated that herbaceous species in desert steppes adapted their water uptake and drought tolerance strategies according to changes in precipitation amount and timing.As a core regulatory mechanism,HNS(under increasing precipitation variability due to climate change)not only supports species coexistence by reducing interspecific competition,but also promotes efficient soil moisture use.This mechanism enhances community drought resistance and contributes to ecosystem stability.Overall,this study provides key ecological evidence for understanding plant community adaptation in arid and semi-arid areas facing the influence of global climate change.
基金funded by the China Postdoctoral Science Foundation(2024M760408)National Natural Science Foundation of China(No.32201304)+1 种基金the Fundamental Research Funds for the Central Universities(No.2412024QD0212412022QD026).
文摘Grasslands are among the world's most threatened ecosystems, and steppe birds face increasing risks from human activities. This study investigates how human impacts affect the distribution and community structure of breeding steppe birds in Inner Mongolia, a biodiversity hotspot in Asia. We conducted standardized point-count surveys across a gradient from intact grasslands to urbanized areas, integrating species occurrence data, functional traits and the Human Footprint Index (HFI). Using Generalized Linear Models (GLMs) and Conditional Random Fields (CRFs), we assessed trait-environment interactions and shifts in species associations. Our results indicate that the HFI significantly affects bird communities. Habitat specialists, such as Mongolian Lark (Melanocorypha mongolica), showed negative responses, whereas generalists like Eurasian Tree Sparrow (Passer montanus) thrived in disturbed areas. Trait-based analysis showed that species with larger body mass and specialized diets were negatively associated with HFI, whereas those linked to human-modified habitats exhibiting strong positive associations. In areas with high human footprint, co-occurrence networks grew more polarized: specialists faced intensified competition, while species with positive HFI responses formed stronger positive associations. CRF models indicated that human activities restructure species interactions, favoring generalists and simplifying community dynamics. These findings highlight the dual role of human impact in supporting some species while threatening specialists, potentially driving biotic homogenization. Our study emphasizes the need for conservation strategies that protect vulnerable species and manage those that thrive in human-altered environments. By linking traits and interactions to human impacts, this study provides a framework for identifying at-risk species and guiding conservation in the Anthropocene.
基金supported by the National Key Research and Development Program of China(2023YFF1304304)。
文摘Tibetan alpine steppes are large and sensitive terrestrial carbon(C)reservoirs that are experiencing desertification due to global change and overgrazing,which can lead to stronger resource limitations for both above-and belowground communities.Soil nutrients,especially nitrogen(N)and phosphorus(P),are the crucial resources for plant growth and microbial metabolism.However,whether both plant and soil microbial communities in the degraded alpine steppes are limited by these soil nutrients remains unclear,which limits our understanding of the mechanisms of desertification and subsequent ecosystem restoration.Here,we evaluated potential nutrient limitations of the plant and soil microbial communities in the alpine steppe across five stages of desertification using stoichiometry-based approaches.Our results showed that soil microbial metabolism was mainly limited by C and P,and the plant N limitation and microbial C limitation were intensified while the microbial P limitation was relieved during desertification.Plant-soil-microbe interactions had significant impacts on the microbial C and P limitations,explaining 72 and 61%of the variation,respectively.Specifically,desertification ultimately affected microbial metabolic limitations by regulating soil pH,soil nutrients,and the plant N limitation.Moreover,the microbial C limitation further reduced microbial C use efficiency(CUE)with desertification,which is detrimental for organic C retention in the degraded soil.Overall,this study revealed that microbial metabolic limitations through plant-microbe interactions were the key drivers affecting soil microbial CUE,and it provided insights that can advance our knowledge of the microbial regulation of nutrient cycles and C sequestration.
