One of the goals of grazing management in the desert steppe is to improve its ecosystem.However,relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management.In this...One of the goals of grazing management in the desert steppe is to improve its ecosystem.However,relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management.In this study,we investigated the diversity and aboveground biomass of Caragana korshinskii Kom.shrub communities in long-term fencing and grazing areas,combined with an analysis of soil physical-chemical properties and genomics,with the aim of understanding how fence management affects plant-soil-microbial inter-relationships in the desert steppe,China.The results showed that fence management(exclosure)increased plant diversity and aboveground biomass in C.korshinskii shrub area and effectively enhanced soil organic carbon(233.94%),available nitrogen(87.77%),and available phosphorus(53.67%)contents.As well,the Shannon indices of soil bacteria and fungi were greater in the fenced plot.Plant-soil changes profoundly affected the alpha-and beta-diversity of soil bacteria.Fence management also altered the soil microbial community structure,significantly increasing the relative abundances of Acidobacteriota(5.31%-8.99%),Chloroflexi(3.99%-5.58%),and Glomeromycota(1.37%-3.28%).The soil bacterial-fungal co-occurrence networks under fence management had higher complexity and connectivity.Based on functional predictions,fence management significantly increased the relative abundance of bacteria with nitrification and nitrate reduction functions and decreased the relative abundance of bacteria with nitrate and nitrite respiration functions.The relative abundances of ecologically functional fungi with arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and saprotrophs also significantly increased under fence management.In addition,the differential functional groups of bacteria and fungi were closely related to plant-soil changes.The results of this study have significant positive implications for the ecological restoration and reconstruction of dry desert steppe and similar areas.展开更多
Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attentio...Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention.Soil microorganisms have been proven to provide nutrients for specific plant growth,especially in nutrient-poor desert steppe ecosystems.However,the effects of N deposition on plant-soil microbial community interactions in such ecosystems remain poorly understood.To investigate these effects,we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb.desert steppe in Inner Mongolia Autonomous Region,China.Four N treatment levels(N0,N30,N50,and N100,corresponding to 0,30,50,and 100 kg N/(hm2•a),respectively)were applied to simulate atmospheric N deposition.The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants.N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in the desert steppe,and low and mediate N additions(N30 and N50)had a promoting effect on them.The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index.N deposition significantly affected the beta-diversity of plants and soil bacteria,but did not significantly affect fungal communities.In conclusion,N deposition led to co-evolution between desert steppe plants and soil bacterial communities,while fungal communities exhibited strong stability and did not undergo significant changes.These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.展开更多
Changes in precipitation and nitrogen(N)addition may significantly affect the processes of soil carbon(C)cycle in terrestrial ecosystems,such as soil respiration.However,relatively few studies have investigated the ef...Changes in precipitation and nitrogen(N)addition may significantly affect the processes of soil carbon(C)cycle in terrestrial ecosystems,such as soil respiration.However,relatively few studies have investigated the effects of changes in precipitation and N addition on soil respiration in the upper soil layer in desert steppes.In this study,we conducted a control experiment that involved a field simulation from July 2020 to December 2021 in a desert steppe in Yanchi County,China.Specifically,we measured soil parameters including soil temperature,soil moisture,total nitrogen(TN),soil organic carbon(SOC),soil microbial biomass carbon(SMBC),soil microbial biomass nitrogen(SMBN),and contents of soil microorganisms including bacteria,fungi,actinomyces,and protozoa,and determined the components of soil respiration including soil respiration with litter(RS+L),soil respiration without litter(RS),and litter respiration(RL)under short-term changes in precipitation(control,increased precipitation by 30%,and decreased precipitation by 30%)and N addition(0.0 and 10.0 g/(m^(2)·a))treatments.Our results indicated that short-term changes in precipitation and N addition had substantial positive effects on the contents of TN,SOC,and SMBC,as well as the contents of soil actinomyces and protozoa.In addition,N addition significantly enhanced the rates of RS+L and RS by 4.8%and 8.0%(P<0.05),respectively.The increase in precipitation markedly increased the rates of RS+L and RS by 2.3%(P<0.05)and 5.7%(P<0.001),respectively.The decrease in precipitation significantly increased the rates of RS+L and RS by 12.9%(P<0.05)and 23.4%(P<0.001),respectively.In contrast,short-term changes in precipitation and N addition had no significant effects on RL rate(P>0.05).The mean RL/RS+L value observed under all treatments was 27.63%,which suggested that RL is an important component of soil respiration in the desert steppe ecosystems.The results also showed that short-term changes in precipitation and N addition had significant interactive effects on the rates of RS+L,RS,and RL(P<0.001).In addition,soil temperature was the most important abiotic factor that affected the rates of RS+L,RS,and RL.Results of the correlation analysis demonstrated that the rates of RS+L,RS,and RL were closely related to soil temperature,soil moisture,TN,SOC,and the contents of soil microorganisms,and the structural equation model revealed that SOC and SMBC are the key factors influencing the rates of RS+L,RS,and RL.This study provides further insights into the characteristics of soil C emissions in desert steppe ecosystems in the context of climate change,which can be used as a reference for future related studies.展开更多
Drought,which restricts the sustainable development of agriculture,ecological health,and social economy,is affected by a variety of factors.It is widely accepted that a single variable cannot fully reflect the charact...Drought,which restricts the sustainable development of agriculture,ecological health,and social economy,is affected by a variety of factors.It is widely accepted that a single variable cannot fully reflect the characteristics of drought events.Studying precipitation,reference evapotranspiration(ET_(0)),and vegetation yield can derive information to help conserve water resources in grassland ecosystems in arid and semi-arid regions.In this study,the interactions of precipitation,ET_(0),and vegetation yield in Darhan Muminggan Joint Banner(DMJB),a desert steppe in Inner Mongolia Autonomous Region,China were explored using two-dimensional(2D)and three-dimensional(3D)joint distribution models.Three types of Copula functions were applied to quantitatively analyze the joint distribution probability of different combinations of precipitation,ET_(0),and vegetation yield.For the precipitation–ET_(0)dry–wet type,the 2D joint distribution probability with precipitation≤245.69 mm/a or ET_(0)≥959.20 mm/a in DMJB was approximately 0.60,while the joint distribution probability with precipitation≤245.69 mm/a and ET_(0)≥959.20 mm/a was approximately 0.20.Correspondingly,the joint return period that at least one of the two events(precipitation was dry or ET_(0)was wet)occurred was 2 a,and the co-occurrence return period that both events(precipitation was dry and ET_(0)was wet)occurred was 5 a.Under this condition,the interval between dry and wet events would be short,the water supply and demand were unbalanced,and the water demand of vegetation would not be met.In addition,when precipitation remained stable and ET_(0)increased,the 3D joint distribution probability that vegetation yield would decrease due to water shortage in the precipitation–ET_(0)dry–wet years could reach up to 0.60–0.70.In future work,irrigation activities and water allocation criteria need to be implemented to increase vegetation yield and the safety of water resources in the desert steppe of Inner Mongolia.展开更多
Maintaining the stability of exotic sand-binding shrub has become a large challenge in arid and semi-arid grassland ecosystems in northern China.We investigated two kinds of shrublands with different BSCs(biological s...Maintaining the stability of exotic sand-binding shrub has become a large challenge in arid and semi-arid grassland ecosystems in northern China.We investigated two kinds of shrublands with different BSCs(biological soil crusts)cover in desert steppe in Northwest China to characterize the water sources of shrub(Caragana intermedia Kuang et H.C.Fu)and grass(Artemisia scoparia Waldst.et Kit.)by stable 18O isotopic.Our results showed that both shrublands were subject to persistent soil water deficiency from 2012 to 2017,the minimum soil depth with CV(coefficient of variation)<15% and SWC(soil water content)<6% was 1.4 m in shrubland with open areas lacking obvious BSC cover,and 0.8 m in shrubland covered by mature BSCs.For C.intermedia,a considerable proportion of water sources pointed to the surface soil.Water from BSCs contributed to averages 22.9%and 17.6%of the total for C.intermedia and A.scoparia,respectively.C.intermedia might use more water from BSCs in rainy season than dry season,in contrast to A.scoparia.The relationship between shrub(or grass)and soil water by δ^(18)O shown significant differences in months,which partly verified the potential trends and relations covered by the high variability of the water source at seasonal scale.More fine roots at 0-5 cm soil layer could be found in the surface soil layer covered by BSCs(8000 cm/m^(3))than without BSCs(3200 cm/m^(3)),which ensured the possibility of using the surface soil water by C.intermedia.The result implies that even under serious soil water deficiency,C.intermedia can use the surface soil water,leading to the coexistence between C.intermedia and A.scoparia.Different with the result from BSCs in desert areas,the natural withdrawal of artificial C.intermedia from desert steppe will be a long-term process,and the highly competitive relationship between shrubs and grasses also determines that its habitat will be maintained in serious drought state for a long time.展开更多
Water is a limiting factor in the restoration and construction of desert steppe.Exploring plant water sources is necessary to understand soil-plant interactions and species coexistence;however,water sources of major p...Water is a limiting factor in the restoration and construction of desert steppe.Exploring plant water sources is necessary to understand soil-plant interactions and species coexistence;however,water sources of major plant communities within the desert steppe of Ningxia Hui Autonomous Region,China remain poorly understood.In this study,we analyzed the water uptake of plants in four typical communities:Agropyron mongolicum Keng.;Sophora alopecuroids Linn.;Stipa breviflora Griseb.,and Achnatherum splendens(Trin.)Nevski communities.Stable isotopesδD andδ^(18)O in the xylem of plant and soil water at different soil depths were analyzed.An IsoSource model was used to determine the soil depths from which plants obtained water.Results showed that A.mongolicum community obtained water predominantly from 0–20 and 40–80 cm depth,S.alopecuroids community from 0–20 cm depth,S.breviflora community from 0–40 cm depth,and A.splendens community from 0–20 and 80–140 cm depths.S.alopecuroides had a wider range of soil depths for water extraction,i.e.,utilizing different water sources depending on habitat,and the plasticity of its water uptake pattern determined its role in different communities.Water source of plants relayed heavily on the distribution of their roots.Competition for soil water exists between different plant life forms in the sierozem habitat(A.mongolicum,S.alopecuroids,and S.breviflora communities),and in the sandy soil habitat(A.splendens community).The use of soil water by A.splendens community is more spatially differentiated,and shrubs and herbs can coexist stably.Under the pattern of extended drought period in the future,sierozem habitat may be more favorable for the formation of a dominant monoculture community type of perennial fibrous plants.In aeolian sandy soil habitat,A.splendens had a strong competitive advantage,and the growth of shallow-rooted plants was easily suppressed.展开更多
In arid and semi-arid desert steppe areas,grazing exclusion with fencing is widely regarded as an effective strategy for restoring degraded vegetation and enhancing the quality of degraded soil.In this study,we hypoth...In arid and semi-arid desert steppe areas,grazing exclusion with fencing is widely regarded as an effective strategy for restoring degraded vegetation and enhancing the quality of degraded soil.In this study,we hypothesized that grazing exclusion caused by fencing enhances both vegetation and soil properties,and that the longer an area is fenced,the more considerable the improvement.We conducted an observational study wherein random sampling was utilized to select 9 plots fenced for ten or more years,25 plots fenced for four to nine years,25 plots fenced for one to three years and 29 free-grazing plots within an area of approximately 63,000 km^(2)of Inner Mongolia desert steppe.A one-way ANOVA revealed no significant differences in the characteristics of grassland vegetation or soil properties between grasslands fenced for one to three years and free-grazing grassland.After 4 years of fencing,noticeable increases in above-ground biomass,litter content,Simpson index,soil organic carbon,and available nitrogen were observed.Significant positive differences in vegetation coverage,height,species richness,soil available phosphorus,and available potassium were associated with plots with a minimum of 10 years of fencing.The soil layer with the greatest difference in the fenced-in areas for soil organic carbon was at 0-25 cm.For available nitrogen and available phosphorus,fencing produced the most significant differences in the 0-20 cm soil layer,while for available potassium,fencing produced the most significant differences in the 0-30 cm soil layer.However,the fencing did not indicate any statistically significant differences in terms of clay,silt,and sand content in any soil layer.The data support our hypothesis that grazing exclusion improves both vegetation and soil properties,and that longer periods of grazing exclusion result in greater degrees of improvement.This research offers technical guidance for the reasonable choice of fencing time across a vast area of the Inner Mongolian desert steppe.展开更多
The dominant parameters in the Noah land surface model(LSM) are identified, and the effects of parameter optimization on the surface heat exchange are investigated at a temperate desert steppe site during growing seas...The dominant parameters in the Noah land surface model(LSM) are identified, and the effects of parameter optimization on the surface heat exchange are investigated at a temperate desert steppe site during growing season in Inner Mongolia, China. The relative impacts of parameters on surface heat flux are examined by the distributed evaluation of local sensitivity analysis(DELSA), and the Noah LSM is calibrated by the global shuffled complex evolution(SCE) against the corresponding observations during May–September of 2008 and 2009. The differences in flux simulations are assessed between the Noah LSM calibrated by the SCE with 27 parameters and 12 dominant parameters.The systematic error, unsystematic error, root mean squared error, and mean squared error decompositions are used to evaluate the model performance. Compared to the control experiment, parameter optimization by the SCE using net radiation, sensible heat flux, latent heat flux, and ground heat flux as the objective criterion, respectively, can obviously reduce the errors of the Noah LSM. The calibrated Noah LSM is further validated against flux observations of growing season in 2010, and it is found that the calibrated Noah LSM can be applied in the longer term at this site.The Noah LSM with 12 dominant parameters calibrated performs similar to that with 27 parameters calibrated.展开更多
Gasterophilus spp.have been found to be widespread in reintroduced Przewalski’s horses in the Kalamaili Nature Reserve(Northwest China).However,data on the annual variation in Gasterophilus infections are lacking.To ...Gasterophilus spp.have been found to be widespread in reintroduced Przewalski’s horses in the Kalamaili Nature Reserve(Northwest China).However,data on the annual variation in Gasterophilus infections are lacking.To analyze the epidemiological features and determine the cause of the annual variation in Gasterophilus infections,we treated 110 Przewalski’s horses with ivermectin and collected Gasterophilus larvae from fecal samples each winter from 2007 to 2019.All 110 Przewalski’s horses studied were found to be infected by Gasterophilus spp.,and a total of 141379 larvae were collected.Six species of Gasterophilus were identified with the following prevalence:G.pecorum(100%),G.nasalis(96.36%),G.nigricornis(94.55%),G.haemorrhoidalis(56.36%),G.intestinalis(59.09%),and G.inermis(3.64%).The mean infection intensity of Gasterophilus spp.larvae in Przewalski’s horses was 1285±653.G.pecorum(92.96%±6.71%)was the most abundant species.The intensity of Gasterophilus spp.(r=–0.561,P<0.046)was significantly correlated with winter precipitation.Our findings confirmed that,in the Kalamaili Nature Reserve,gasterophilosis is a severe parasitic disease in Przewalski’s horses.Winter precipitation at the beginning of the year can indirectly affect the intensity and composition of Gasterophilus spp.in Przewalski’s horses at the end of the year.Therefore,the water-related ecological regulation should be carried out to help reduce the parasite infection of Przewalski’s horses.展开更多
Polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)technique was employed to examine the seasonal dynamic changes in bacterial community composition in the Inner Mongolia desert steppe using sp...Polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)technique was employed to examine the seasonal dynamic changes in bacterial community composition in the Inner Mongolia desert steppe using specific primers F954 and R1369.Bright and reproducible bands were sequenced,and the phylogenic tree was constructed.The results show that the bacterial community composition changed between different seasons.The specific bands were different between the sampling sites with light and heavy levels of degraded grassland.Three main types of bacteria constituting the microbial community in the Inner Mongolia desert steppe belonged to the α,γ and δ-sub phyla of Proteobacteria,Bacteroidetes and Acidobacteria.The unculturable bacteria accounted for 69%of the whole bacterial community of the Inner Mongolia desert steppe.展开更多
This paper analyzed relative ecological value of several major plants in Minqin desert grassland using layered projection of plant canopy. The results showed that ecological functions of natural Nitraria tangutorum an...This paper analyzed relative ecological value of several major plants in Minqin desert grassland using layered projection of plant canopy. The results showed that ecological functions of natural Nitraria tangutorum and Ephedra sinica woods of a unit area were much better than those of artifi cial Haloxylon ammodendron woods, relative ecological value of N. tangutorum, E. sinica and Artemisia desertorum were much higher than that of artifi cial H. ammodendron woods. Layered projection explains clearly the ecological functions and relative ecological value of desert vegetation of the same coverage. It is inaccurate to indicate wind prevention and sand fi xation of desert vegetation in deserts using ecological function service value and ecological niche calculated on the basis of two-dimensional vegetation coverage, but three-dimensional projection degree should be applied to indicate ecological functions and relative ecological value of vegetation. Application of layered projection of plants in calculating ecological functions and relative ecological value of desert plants(vegetation) is the innovation point of this research.展开更多
基金funded by the National Natural Science Foundation of China(32061123006,32360426).
文摘One of the goals of grazing management in the desert steppe is to improve its ecosystem.However,relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management.In this study,we investigated the diversity and aboveground biomass of Caragana korshinskii Kom.shrub communities in long-term fencing and grazing areas,combined with an analysis of soil physical-chemical properties and genomics,with the aim of understanding how fence management affects plant-soil-microbial inter-relationships in the desert steppe,China.The results showed that fence management(exclosure)increased plant diversity and aboveground biomass in C.korshinskii shrub area and effectively enhanced soil organic carbon(233.94%),available nitrogen(87.77%),and available phosphorus(53.67%)contents.As well,the Shannon indices of soil bacteria and fungi were greater in the fenced plot.Plant-soil changes profoundly affected the alpha-and beta-diversity of soil bacteria.Fence management also altered the soil microbial community structure,significantly increasing the relative abundances of Acidobacteriota(5.31%-8.99%),Chloroflexi(3.99%-5.58%),and Glomeromycota(1.37%-3.28%).The soil bacterial-fungal co-occurrence networks under fence management had higher complexity and connectivity.Based on functional predictions,fence management significantly increased the relative abundance of bacteria with nitrification and nitrate reduction functions and decreased the relative abundance of bacteria with nitrate and nitrite respiration functions.The relative abundances of ecologically functional fungi with arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and saprotrophs also significantly increased under fence management.In addition,the differential functional groups of bacteria and fungi were closely related to plant-soil changes.The results of this study have significant positive implications for the ecological restoration and reconstruction of dry desert steppe and similar areas.
基金the National Natural Science Foundation of China(31860136,31560156)the Basic Scientific Research Service Fee Project of Colleges and Universities of Inner Mongolia Autonomous Regionthe Graduate Scientific Research Innovation Project of Inner Mongolia Autonomous Region(B20210158Z).
文摘Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention.Soil microorganisms have been proven to provide nutrients for specific plant growth,especially in nutrient-poor desert steppe ecosystems.However,the effects of N deposition on plant-soil microbial community interactions in such ecosystems remain poorly understood.To investigate these effects,we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb.desert steppe in Inner Mongolia Autonomous Region,China.Four N treatment levels(N0,N30,N50,and N100,corresponding to 0,30,50,and 100 kg N/(hm2•a),respectively)were applied to simulate atmospheric N deposition.The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants.N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in the desert steppe,and low and mediate N additions(N30 and N50)had a promoting effect on them.The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index.N deposition significantly affected the beta-diversity of plants and soil bacteria,but did not significantly affect fungal communities.In conclusion,N deposition led to co-evolution between desert steppe plants and soil bacterial communities,while fungal communities exhibited strong stability and did not undergo significant changes.These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.
基金supported by the National Natural Science Foundation of China(31960359)the Ningxia Hui Autonomous Region Key Research and Development Project(2021BEG02005,2023BEG02049)the Natural Science Foundation of Ningxia Hui Autonomous Region,China(2020AAC03102,2023AAC03061)。
文摘Changes in precipitation and nitrogen(N)addition may significantly affect the processes of soil carbon(C)cycle in terrestrial ecosystems,such as soil respiration.However,relatively few studies have investigated the effects of changes in precipitation and N addition on soil respiration in the upper soil layer in desert steppes.In this study,we conducted a control experiment that involved a field simulation from July 2020 to December 2021 in a desert steppe in Yanchi County,China.Specifically,we measured soil parameters including soil temperature,soil moisture,total nitrogen(TN),soil organic carbon(SOC),soil microbial biomass carbon(SMBC),soil microbial biomass nitrogen(SMBN),and contents of soil microorganisms including bacteria,fungi,actinomyces,and protozoa,and determined the components of soil respiration including soil respiration with litter(RS+L),soil respiration without litter(RS),and litter respiration(RL)under short-term changes in precipitation(control,increased precipitation by 30%,and decreased precipitation by 30%)and N addition(0.0 and 10.0 g/(m^(2)·a))treatments.Our results indicated that short-term changes in precipitation and N addition had substantial positive effects on the contents of TN,SOC,and SMBC,as well as the contents of soil actinomyces and protozoa.In addition,N addition significantly enhanced the rates of RS+L and RS by 4.8%and 8.0%(P<0.05),respectively.The increase in precipitation markedly increased the rates of RS+L and RS by 2.3%(P<0.05)and 5.7%(P<0.001),respectively.The decrease in precipitation significantly increased the rates of RS+L and RS by 12.9%(P<0.05)and 23.4%(P<0.001),respectively.In contrast,short-term changes in precipitation and N addition had no significant effects on RL rate(P>0.05).The mean RL/RS+L value observed under all treatments was 27.63%,which suggested that RL is an important component of soil respiration in the desert steppe ecosystems.The results also showed that short-term changes in precipitation and N addition had significant interactive effects on the rates of RS+L,RS,and RL(P<0.001).In addition,soil temperature was the most important abiotic factor that affected the rates of RS+L,RS,and RL.Results of the correlation analysis demonstrated that the rates of RS+L,RS,and RL were closely related to soil temperature,soil moisture,TN,SOC,and the contents of soil microorganisms,and the structural equation model revealed that SOC and SMBC are the key factors influencing the rates of RS+L,RS,and RL.This study provides further insights into the characteristics of soil C emissions in desert steppe ecosystems in the context of climate change,which can be used as a reference for future related studies.
基金This research was supported by the Natural Science Foundation of Inner Mongolia Autonomous Region,China(2022QN04003)the Central Government to Guide Local Scientific and Technological Development(2021ZY0031).
文摘Drought,which restricts the sustainable development of agriculture,ecological health,and social economy,is affected by a variety of factors.It is widely accepted that a single variable cannot fully reflect the characteristics of drought events.Studying precipitation,reference evapotranspiration(ET_(0)),and vegetation yield can derive information to help conserve water resources in grassland ecosystems in arid and semi-arid regions.In this study,the interactions of precipitation,ET_(0),and vegetation yield in Darhan Muminggan Joint Banner(DMJB),a desert steppe in Inner Mongolia Autonomous Region,China were explored using two-dimensional(2D)and three-dimensional(3D)joint distribution models.Three types of Copula functions were applied to quantitatively analyze the joint distribution probability of different combinations of precipitation,ET_(0),and vegetation yield.For the precipitation–ET_(0)dry–wet type,the 2D joint distribution probability with precipitation≤245.69 mm/a or ET_(0)≥959.20 mm/a in DMJB was approximately 0.60,while the joint distribution probability with precipitation≤245.69 mm/a and ET_(0)≥959.20 mm/a was approximately 0.20.Correspondingly,the joint return period that at least one of the two events(precipitation was dry or ET_(0)was wet)occurred was 2 a,and the co-occurrence return period that both events(precipitation was dry and ET_(0)was wet)occurred was 5 a.Under this condition,the interval between dry and wet events would be short,the water supply and demand were unbalanced,and the water demand of vegetation would not be met.In addition,when precipitation remained stable and ET_(0)increased,the 3D joint distribution probability that vegetation yield would decrease due to water shortage in the precipitation–ET_(0)dry–wet years could reach up to 0.60–0.70.In future work,irrigation activities and water allocation criteria need to be implemented to increase vegetation yield and the safety of water resources in the desert steppe of Inner Mongolia.
基金This research was funded by the National Natural Science Foundation of China(32060313,31760707).
文摘Maintaining the stability of exotic sand-binding shrub has become a large challenge in arid and semi-arid grassland ecosystems in northern China.We investigated two kinds of shrublands with different BSCs(biological soil crusts)cover in desert steppe in Northwest China to characterize the water sources of shrub(Caragana intermedia Kuang et H.C.Fu)and grass(Artemisia scoparia Waldst.et Kit.)by stable 18O isotopic.Our results showed that both shrublands were subject to persistent soil water deficiency from 2012 to 2017,the minimum soil depth with CV(coefficient of variation)<15% and SWC(soil water content)<6% was 1.4 m in shrubland with open areas lacking obvious BSC cover,and 0.8 m in shrubland covered by mature BSCs.For C.intermedia,a considerable proportion of water sources pointed to the surface soil.Water from BSCs contributed to averages 22.9%and 17.6%of the total for C.intermedia and A.scoparia,respectively.C.intermedia might use more water from BSCs in rainy season than dry season,in contrast to A.scoparia.The relationship between shrub(or grass)and soil water by δ^(18)O shown significant differences in months,which partly verified the potential trends and relations covered by the high variability of the water source at seasonal scale.More fine roots at 0-5 cm soil layer could be found in the surface soil layer covered by BSCs(8000 cm/m^(3))than without BSCs(3200 cm/m^(3)),which ensured the possibility of using the surface soil water by C.intermedia.The result implies that even under serious soil water deficiency,C.intermedia can use the surface soil water,leading to the coexistence between C.intermedia and A.scoparia.Different with the result from BSCs in desert areas,the natural withdrawal of artificial C.intermedia from desert steppe will be a long-term process,and the highly competitive relationship between shrubs and grasses also determines that its habitat will be maintained in serious drought state for a long time.
基金supported by the National Natural Science Foundation of China(32171872,31901367)the Key R&D Projects in Ningxia,China(2019BFG02022)+2 种基金the Young Science and Technology Talents Promotion Project(the fifth batch)in Ningxia,Chinathe Agricultural Science and Technology Funding Innovation Project,in Ningxia,China(NGSB-2021-14-03)the Ningxia Natural Science Foundation(2021AAC03015)。
文摘Water is a limiting factor in the restoration and construction of desert steppe.Exploring plant water sources is necessary to understand soil-plant interactions and species coexistence;however,water sources of major plant communities within the desert steppe of Ningxia Hui Autonomous Region,China remain poorly understood.In this study,we analyzed the water uptake of plants in four typical communities:Agropyron mongolicum Keng.;Sophora alopecuroids Linn.;Stipa breviflora Griseb.,and Achnatherum splendens(Trin.)Nevski communities.Stable isotopesδD andδ^(18)O in the xylem of plant and soil water at different soil depths were analyzed.An IsoSource model was used to determine the soil depths from which plants obtained water.Results showed that A.mongolicum community obtained water predominantly from 0–20 and 40–80 cm depth,S.alopecuroids community from 0–20 cm depth,S.breviflora community from 0–40 cm depth,and A.splendens community from 0–20 and 80–140 cm depths.S.alopecuroides had a wider range of soil depths for water extraction,i.e.,utilizing different water sources depending on habitat,and the plasticity of its water uptake pattern determined its role in different communities.Water source of plants relayed heavily on the distribution of their roots.Competition for soil water exists between different plant life forms in the sierozem habitat(A.mongolicum,S.alopecuroids,and S.breviflora communities),and in the sandy soil habitat(A.splendens community).The use of soil water by A.splendens community is more spatially differentiated,and shrubs and herbs can coexist stably.Under the pattern of extended drought period in the future,sierozem habitat may be more favorable for the formation of a dominant monoculture community type of perennial fibrous plants.In aeolian sandy soil habitat,A.splendens had a strong competitive advantage,and the growth of shallow-rooted plants was easily suppressed.
基金supported by a sub-project of the National Key R&D Project of China(Grant No.2016YFC0501003)the National Key R&D Project of China(Grant No.2021YFD1500704).
文摘In arid and semi-arid desert steppe areas,grazing exclusion with fencing is widely regarded as an effective strategy for restoring degraded vegetation and enhancing the quality of degraded soil.In this study,we hypothesized that grazing exclusion caused by fencing enhances both vegetation and soil properties,and that the longer an area is fenced,the more considerable the improvement.We conducted an observational study wherein random sampling was utilized to select 9 plots fenced for ten or more years,25 plots fenced for four to nine years,25 plots fenced for one to three years and 29 free-grazing plots within an area of approximately 63,000 km^(2)of Inner Mongolia desert steppe.A one-way ANOVA revealed no significant differences in the characteristics of grassland vegetation or soil properties between grasslands fenced for one to three years and free-grazing grassland.After 4 years of fencing,noticeable increases in above-ground biomass,litter content,Simpson index,soil organic carbon,and available nitrogen were observed.Significant positive differences in vegetation coverage,height,species richness,soil available phosphorus,and available potassium were associated with plots with a minimum of 10 years of fencing.The soil layer with the greatest difference in the fenced-in areas for soil organic carbon was at 0-25 cm.For available nitrogen and available phosphorus,fencing produced the most significant differences in the 0-20 cm soil layer,while for available potassium,fencing produced the most significant differences in the 0-30 cm soil layer.However,the fencing did not indicate any statistically significant differences in terms of clay,silt,and sand content in any soil layer.The data support our hypothesis that grazing exclusion improves both vegetation and soil properties,and that longer periods of grazing exclusion result in greater degrees of improvement.This research offers technical guidance for the reasonable choice of fencing time across a vast area of the Inner Mongolian desert steppe.
基金Supported by the National Natural Science Foundation of China(41505010)Chinese Academy of Meteorological Sciences(CAMS)Basic Research Special Project(2017Y014 and 2015Z002)+1 种基金China Meteorological Administration Special Public Welfare Research Fund(GYHY201506001)National Basic Research and Development(973)Program of China(2010CB951303)
文摘The dominant parameters in the Noah land surface model(LSM) are identified, and the effects of parameter optimization on the surface heat exchange are investigated at a temperate desert steppe site during growing season in Inner Mongolia, China. The relative impacts of parameters on surface heat flux are examined by the distributed evaluation of local sensitivity analysis(DELSA), and the Noah LSM is calibrated by the global shuffled complex evolution(SCE) against the corresponding observations during May–September of 2008 and 2009. The differences in flux simulations are assessed between the Noah LSM calibrated by the SCE with 27 parameters and 12 dominant parameters.The systematic error, unsystematic error, root mean squared error, and mean squared error decompositions are used to evaluate the model performance. Compared to the control experiment, parameter optimization by the SCE using net radiation, sensible heat flux, latent heat flux, and ground heat flux as the objective criterion, respectively, can obviously reduce the errors of the Noah LSM. The calibrated Noah LSM is further validated against flux observations of growing season in 2010, and it is found that the calibrated Noah LSM can be applied in the longer term at this site.The Noah LSM with 12 dominant parameters calibrated performs similar to that with 27 parameters calibrated.
基金supported by the National Science Foundation of China(No.31670538,No.30870463)the Project of Department for Wildlife and Forest Plants Protection,SFA of China(No.2018123).
文摘Gasterophilus spp.have been found to be widespread in reintroduced Przewalski’s horses in the Kalamaili Nature Reserve(Northwest China).However,data on the annual variation in Gasterophilus infections are lacking.To analyze the epidemiological features and determine the cause of the annual variation in Gasterophilus infections,we treated 110 Przewalski’s horses with ivermectin and collected Gasterophilus larvae from fecal samples each winter from 2007 to 2019.All 110 Przewalski’s horses studied were found to be infected by Gasterophilus spp.,and a total of 141379 larvae were collected.Six species of Gasterophilus were identified with the following prevalence:G.pecorum(100%),G.nasalis(96.36%),G.nigricornis(94.55%),G.haemorrhoidalis(56.36%),G.intestinalis(59.09%),and G.inermis(3.64%).The mean infection intensity of Gasterophilus spp.larvae in Przewalski’s horses was 1285±653.G.pecorum(92.96%±6.71%)was the most abundant species.The intensity of Gasterophilus spp.(r=–0.561,P<0.046)was significantly correlated with winter precipitation.Our findings confirmed that,in the Kalamaili Nature Reserve,gasterophilosis is a severe parasitic disease in Przewalski’s horses.Winter precipitation at the beginning of the year can indirectly affect the intensity and composition of Gasterophilus spp.in Przewalski’s horses at the end of the year.Therefore,the water-related ecological regulation should be carried out to help reduce the parasite infection of Przewalski’s horses.
基金This work was supported by the National Natural Science Foundation of China(Grant No.30560030)the University Scientific Research Foundation of Inner Mongolia(No.NJ05099).
文摘Polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)technique was employed to examine the seasonal dynamic changes in bacterial community composition in the Inner Mongolia desert steppe using specific primers F954 and R1369.Bright and reproducible bands were sequenced,and the phylogenic tree was constructed.The results show that the bacterial community composition changed between different seasons.The specific bands were different between the sampling sites with light and heavy levels of degraded grassland.Three main types of bacteria constituting the microbial community in the Inner Mongolia desert steppe belonged to the α,γ and δ-sub phyla of Proteobacteria,Bacteroidetes and Acidobacteria.The unculturable bacteria accounted for 69%of the whole bacterial community of the Inner Mongolia desert steppe.
基金Sponsored by Pilot Study of National 973 Plan(2014CB460611)The National Natural Science Fund(41261102)
文摘This paper analyzed relative ecological value of several major plants in Minqin desert grassland using layered projection of plant canopy. The results showed that ecological functions of natural Nitraria tangutorum and Ephedra sinica woods of a unit area were much better than those of artifi cial Haloxylon ammodendron woods, relative ecological value of N. tangutorum, E. sinica and Artemisia desertorum were much higher than that of artifi cial H. ammodendron woods. Layered projection explains clearly the ecological functions and relative ecological value of desert vegetation of the same coverage. It is inaccurate to indicate wind prevention and sand fi xation of desert vegetation in deserts using ecological function service value and ecological niche calculated on the basis of two-dimensional vegetation coverage, but three-dimensional projection degree should be applied to indicate ecological functions and relative ecological value of vegetation. Application of layered projection of plants in calculating ecological functions and relative ecological value of desert plants(vegetation) is the innovation point of this research.
