Growth of annual plants in arid environments depends largely on rainfall pulses. An increased understanding of the effects of different rainfall patterns on plant growth is critical to predicting the potential respons...Growth of annual plants in arid environments depends largely on rainfall pulses. An increased understanding of the effects of different rainfall patterns on plant growth is critical to predicting the potential responses of plants to the changes in rainfall regimes, such as rainfall intensity and duration, and length of dry intervals. In this study, we investigated the effects of different rainfall patterns(e.g. small rainfall event with high frequency and large rainfall event with low frequency) on biomass, growth characteristics and vertical distribution of root biomass of annual plants in Horqin Sandy Land, Inner Mongolia of China during the growing season(from May to August) of 2014. Our results showed that the rainfall patterns, independent of total rainfall amount, exerted strong effects on biomass, characteristics of plant growth and vertical distribution of root biomass. Under a constant amount of total rainfall, the aboveground biomass(AGB), belowground biomass(BGB), plant cover, plant height, and plant individual and species number increased with an increase in rainfall intensity. Changes in rainfall patterns also altered the percentage contribution of species biomass to the total AGB, and the percentage of BGB at different soil layers to the total BGB. Consequently, our results indicated that increased rainfall intensity in future may increase biomass significantly, and also affect the growth characteristics of annual plants.展开更多
Zygophyllum xanthoxylum, which belongs to Sarcozygium of Zygophyllaceae, is one of the ecologically important species in Northwest China. In order to understand the pollination system of Z. xanthoxylum, we investigate...Zygophyllum xanthoxylum, which belongs to Sarcozygium of Zygophyllaceae, is one of the ecologically important species in Northwest China. In order to understand the pollination system of Z. xanthoxylum, we investigated the following characteristics of this species in the Urat Desert-grassland Research Station in western Inner Mongolia of China: flowering dynamics, pollen viability, pollen limitation, floral visitors and breeding system. The results showed that the flowering period and flowering peak were different between the wild and managed populations, being longer in the managed population. Z. xanthoxylum was pollen-limited, and pollen limitation was more intense in the wild population than in the managed population. Chalicodoma deserticola(Hymenoptera) was found to be the most frequent pollinator in the wild population, while Anthophora fulvitarsis(Hymenoptera) was the most frequent and effective visitor in the managed population. Out-crossing was dominant in the breeding system and self-pollination just played an assistant role to assure the reproduction of Z. xanthoxylum.展开更多
Afforestation is conducive to soil carbon(C) sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon(SOC) fractions in ...Afforestation is conducive to soil carbon(C) sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon(SOC) fractions in semi-arid sandy lands. In the present study, we examined the effects of Caragana microphylla Lam. plantations with different ages(12-and 25-year-old) on sequestrations of total SOC as well as labile SOC fractions such as light fraction organic carbon(LFOC) and microbial biomass carbon(MBC). The analyzed samples were taken from soil depths of 0–5 and 5–15 cm under two shrub-related scenarios: under shrubs and between shrubs with moving sand dunes as control sites in the Horqin Sandy Land of northern China. The results showed that the concentrations and storages of total SOC at soil depths of 0–5 and 5–15 cm were higher in 12-and 25-year-old C. microphylla plantations than in moving sand dunes(i.e., control sites), with the highest value observed under shrubs in 25-year-old C. microphylla plantations. Furthermore, the concentrations and storages of LFOC and MBC showed similar patterns with those of total SOC at the same soil depth. The 12-year-old C. microphylla plantations had higher percentages of LFOC concentration to SOC concentration and MBC concentration to SOC concentration than the 25-year-old C. microphylla plantations and moving sand dunes at both soil depths. A significant positive correlation existed among SOC, LFOC, and MBC, implying that restoring the total and labile SOC fractions is possible by afforestation with C. microphylla shrubs in the Horqin Sandy Land. At soil depth of 0–15 cm, the accumulation rate of total SOC under shrubs was higher in young C. microphylla plantations(18.53 g C/(m^2·a); 0–12 years) than in old C. microphylla plantations(16.24 g C/(m^2·a); 12–25 years), and the accumulation rates of LFOC and MBC under shrubs and between shrubs were also higher in young C. microphylla plantations than in old C. microphylla plantations. It can be concluded that the establishment of C. microphylla in the Horqin Sandy Land may be a good mitigation strategy for SOC sequestration in the surface soils.展开更多
Croplands are often suffering from sand burial in dry regions of northern China.For studying this phenomenon,we carried out a case study of field experiment including four sand burial levels,i.e.shallow(1–3 cm),moder...Croplands are often suffering from sand burial in dry regions of northern China.For studying this phenomenon,we carried out a case study of field experiment including four sand burial levels,i.e.shallow(1–3 cm),moderate(8–12 cm)and deep(15–20 cm)sand burials,and no sand burial(control,CK),in a typical agro-pastoral transitional zone in Naiman Banner of eastern Inner Mongolia.The aim of this study was to assess the impacts of sand burial on maize(Zea mays L.)productivity and the soil quality along a gradient of burial depths.Results showed that there was a strong negative effect of sand burial on maize productivity and soil quality,which significantly declined(P<0.05)under moderate and deep sand burial treatments.In comparison with the CK,the maize yield and above-ground biomass reduced by 47.41% and 39.47%,respectively.The soil silt and clay,soil water,soil organic carbon and total nitrogen contents under deep sand burial decreased by 67.85%,40.32%,86.52% and 82.11%,respectively,while microbial biomass carbon,microbial abundance and enzyme activity decreased by 89.78%,42.28%–79.66% and 69.51%–97.71%,respectively.There was no significant effect on crop productivity and soil quality with shallow sand burial treatment.The correlations analysis showed that there was significant positive correlations of both maize yield and above-ground biomass with soil silt and clay,soil organic carbon and total nitrogen contents,p H,electrical conductivity,soil water content,microbial abundance and biomass and all tested soil enzyme activities.Stepwise regression analysis indicated that soil water and total nitrogen contents,urease,cellobiohydrolase and peroxidase activities were key determining factors for maize productivity.This combination of factors explains reason of the decreased maize productivity with deep sand burial.We found that degradation of cropland as a result of sand burial changed soil physical-chemical properties and soil enzyme activities in the plow layer,and decreased overall maize productivity.Furthermore,decreased soil enzyme activity was a better indicator to predict sandy cropland degradation.展开更多
Atmospheric particle pollution is one of the major factors leading to degradation of ancient wall paintings,particularly heritage sites in arid and semi-arid regions.However,current systematic research on the changes,...Atmospheric particle pollution is one of the major factors leading to degradation of ancient wall paintings,particularly heritage sites in arid and semi-arid regions.However,current systematic research on the changes,sources,and influential factors of atmospheric particulate matter and its water-soluble ion concentrations is not sufficient.Thus,the major water-soluble ion concentrations,sources,and influential factors of atmospheric particles PM_(2.5) and PM_(10)(particulate matter with an aerodynamic equivalent diameter≤2.5 and 10.0μm,respectively,in ambient air)were collected from Cave 16 and its ambient exterior environment in the Dunhuang Mogao Grottoes,China,between April 2015 and March 2016.Results showed that the concentrations of PM_(2.5) and PM_(10) inside and outside the cave were the highest in March 2016 and the lowest in December 2015.The higher particle concentration from March to May was related to the frequent occurrence of sand and dust events,and the lower particle concentration from June to September was associated with good diffusion conditions,increased precipitation,and an established cave shelterbelt.The concentration of particulate matter inside the cave was affected by the concentration of particles in the air outside the cave.Ca2+,NH+4,Na+,Cl-,and SO2-4were the main components of the total ions of PM_(2.5) and PM_(10) both inside and outside the cave.The total ions inside the cave were frequently affected by the disturbance of tourists'activities during the peak tourist season from May to August.Under the influence of dust,the total concentrations of Cl-,SO2-4,Na+,NH+4,and Ca2+in particles of different sizes inside and outside the cave increased,and the concentrations of Cl-,SO2-4,Na+,and Ca2+decreased during precipitation period.Backward air mass trajectory analysis suggested that the pollutants were mainly from Xinjiang,China.The pollutant sources of air particulates are straw burning,secondary pollution sources,soil dust,dry spring rivers,and tourist activities.展开更多
Understanding the status and distribution of the micronutrient Zn in soils is important for managing plant growth and preventing soil pollution for agricultural irrigation systems in arid and semi-arid regions.In this...Understanding the status and distribution of the micronutrient Zn in soils is important for managing plant growth and preventing soil pollution for agricultural irrigation systems in arid and semi-arid regions.In this study,a total of 195 soil samples from five soil layers(0–20,20–40,40–60,60–80 and 80–100 cm) in the three land-use types(wasteland,forestland and cropland) after long-term agricultural fertilization and irrigation with Yellow River water were collected in the middle of the Hetao oasis,i.e.the Yongji irrigation sub-oasis.We analyzed the vertical and spatial distributions of Zn content and its relationship with soil properties to determine whether differences of Zn content existed in the soil profiles.The results revealed that the mean content of Zn was 107 mg/kg,1.9 times higher than the background value(55.7 mg/kg) of the Hetao oasis and much lower than the secondary standard value(300 mg/kg) of the Chinese Environmental Quality Standard for Soils when p H>7.5.Soil Zn contents were not significantly different and the coefficients of variation of Zn contents were less than 50% in the five soil layers.Soil Zn content was similar from southern to northern parts but increased from western to eastern parts in the sub-oasis.Soil Zn contents did not differ significantly among the three land-use types,but soil total nitrogen(TN) contents were significantly higher in the agriculturally managed forestland and cropland than in the wasteland(P<0.05).Zn was significantly and positively correlated with TN(F=36.6,P<0.001).The use of fertilizers may increase the content of Zn in soils,but flooding irrigation may minimize the differences in the spatial distribution of soil Zn content in the whole sub-oasis.This research is of important value for soil pollution control and sustainable land use management in arid and semi-arid regions.展开更多
基金supported by the Strategic Leading Science and Technology Projects of Chinese Academy of Sciences (XDA05050201-04-01)the National Natural Science Foundation of China (41371053, 31500369)the ‘One Hundred Talent’ Program of Chinese Academy of Sciences (Y451H31001)
文摘Growth of annual plants in arid environments depends largely on rainfall pulses. An increased understanding of the effects of different rainfall patterns on plant growth is critical to predicting the potential responses of plants to the changes in rainfall regimes, such as rainfall intensity and duration, and length of dry intervals. In this study, we investigated the effects of different rainfall patterns(e.g. small rainfall event with high frequency and large rainfall event with low frequency) on biomass, growth characteristics and vertical distribution of root biomass of annual plants in Horqin Sandy Land, Inner Mongolia of China during the growing season(from May to August) of 2014. Our results showed that the rainfall patterns, independent of total rainfall amount, exerted strong effects on biomass, characteristics of plant growth and vertical distribution of root biomass. Under a constant amount of total rainfall, the aboveground biomass(AGB), belowground biomass(BGB), plant cover, plant height, and plant individual and species number increased with an increase in rainfall intensity. Changes in rainfall patterns also altered the percentage contribution of species biomass to the total AGB, and the percentage of BGB at different soil layers to the total BGB. Consequently, our results indicated that increased rainfall intensity in future may increase biomass significantly, and also affect the growth characteristics of annual plants.
基金funded by the National Science and Technology Support Program (2011BAC07B02)the National Natural Science Foundation of China (41071185)
文摘Zygophyllum xanthoxylum, which belongs to Sarcozygium of Zygophyllaceae, is one of the ecologically important species in Northwest China. In order to understand the pollination system of Z. xanthoxylum, we investigated the following characteristics of this species in the Urat Desert-grassland Research Station in western Inner Mongolia of China: flowering dynamics, pollen viability, pollen limitation, floral visitors and breeding system. The results showed that the flowering period and flowering peak were different between the wild and managed populations, being longer in the managed population. Z. xanthoxylum was pollen-limited, and pollen limitation was more intense in the wild population than in the managed population. Chalicodoma deserticola(Hymenoptera) was found to be the most frequent pollinator in the wild population, while Anthophora fulvitarsis(Hymenoptera) was the most frequent and effective visitor in the managed population. Out-crossing was dominant in the breeding system and self-pollination just played an assistant role to assure the reproduction of Z. xanthoxylum.
基金funded by the National Natural Science Foundation of China (31640012, 41271007, 31660232)the One Hundred Person Project of the Chinese Academy of Sciences (Y551821)+1 种基金the Opening Foundation of the State Key Laboratory Breeding Base of DesertificationAeolian Sand Disaster Combating, Gansu Desert Control Research Institute (GSDC201505)
文摘Afforestation is conducive to soil carbon(C) sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon(SOC) fractions in semi-arid sandy lands. In the present study, we examined the effects of Caragana microphylla Lam. plantations with different ages(12-and 25-year-old) on sequestrations of total SOC as well as labile SOC fractions such as light fraction organic carbon(LFOC) and microbial biomass carbon(MBC). The analyzed samples were taken from soil depths of 0–5 and 5–15 cm under two shrub-related scenarios: under shrubs and between shrubs with moving sand dunes as control sites in the Horqin Sandy Land of northern China. The results showed that the concentrations and storages of total SOC at soil depths of 0–5 and 5–15 cm were higher in 12-and 25-year-old C. microphylla plantations than in moving sand dunes(i.e., control sites), with the highest value observed under shrubs in 25-year-old C. microphylla plantations. Furthermore, the concentrations and storages of LFOC and MBC showed similar patterns with those of total SOC at the same soil depth. The 12-year-old C. microphylla plantations had higher percentages of LFOC concentration to SOC concentration and MBC concentration to SOC concentration than the 25-year-old C. microphylla plantations and moving sand dunes at both soil depths. A significant positive correlation existed among SOC, LFOC, and MBC, implying that restoring the total and labile SOC fractions is possible by afforestation with C. microphylla shrubs in the Horqin Sandy Land. At soil depth of 0–15 cm, the accumulation rate of total SOC under shrubs was higher in young C. microphylla plantations(18.53 g C/(m^2·a); 0–12 years) than in old C. microphylla plantations(16.24 g C/(m^2·a); 12–25 years), and the accumulation rates of LFOC and MBC under shrubs and between shrubs were also higher in young C. microphylla plantations than in old C. microphylla plantations. It can be concluded that the establishment of C. microphylla in the Horqin Sandy Land may be a good mitigation strategy for SOC sequestration in the surface soils.
基金financially supported by the National Natural Science Foundation of China (41401620,41271007)the Hundred Talents Program of Chinese Academy of Sciences (Y451H31001,Y551821001)the Key Laboratory of Desert and Desertification Foundation from Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences (KLDD-2014-010)
文摘Croplands are often suffering from sand burial in dry regions of northern China.For studying this phenomenon,we carried out a case study of field experiment including four sand burial levels,i.e.shallow(1–3 cm),moderate(8–12 cm)and deep(15–20 cm)sand burials,and no sand burial(control,CK),in a typical agro-pastoral transitional zone in Naiman Banner of eastern Inner Mongolia.The aim of this study was to assess the impacts of sand burial on maize(Zea mays L.)productivity and the soil quality along a gradient of burial depths.Results showed that there was a strong negative effect of sand burial on maize productivity and soil quality,which significantly declined(P<0.05)under moderate and deep sand burial treatments.In comparison with the CK,the maize yield and above-ground biomass reduced by 47.41% and 39.47%,respectively.The soil silt and clay,soil water,soil organic carbon and total nitrogen contents under deep sand burial decreased by 67.85%,40.32%,86.52% and 82.11%,respectively,while microbial biomass carbon,microbial abundance and enzyme activity decreased by 89.78%,42.28%–79.66% and 69.51%–97.71%,respectively.There was no significant effect on crop productivity and soil quality with shallow sand burial treatment.The correlations analysis showed that there was significant positive correlations of both maize yield and above-ground biomass with soil silt and clay,soil organic carbon and total nitrogen contents,p H,electrical conductivity,soil water content,microbial abundance and biomass and all tested soil enzyme activities.Stepwise regression analysis indicated that soil water and total nitrogen contents,urease,cellobiohydrolase and peroxidase activities were key determining factors for maize productivity.This combination of factors explains reason of the decreased maize productivity with deep sand burial.We found that degradation of cropland as a result of sand burial changed soil physical-chemical properties and soil enzyme activities in the plow layer,and decreased overall maize productivity.Furthermore,decreased soil enzyme activity was a better indicator to predict sandy cropland degradation.
基金supported by the National Natural Science Foundation of China(51962001,32260292)the National Key Research&Development Projects(2020YFC1522200)the Gansu Provincial Science and Technology Plan Project(20JR5RA051,21YF1FF371).
文摘Atmospheric particle pollution is one of the major factors leading to degradation of ancient wall paintings,particularly heritage sites in arid and semi-arid regions.However,current systematic research on the changes,sources,and influential factors of atmospheric particulate matter and its water-soluble ion concentrations is not sufficient.Thus,the major water-soluble ion concentrations,sources,and influential factors of atmospheric particles PM_(2.5) and PM_(10)(particulate matter with an aerodynamic equivalent diameter≤2.5 and 10.0μm,respectively,in ambient air)were collected from Cave 16 and its ambient exterior environment in the Dunhuang Mogao Grottoes,China,between April 2015 and March 2016.Results showed that the concentrations of PM_(2.5) and PM_(10) inside and outside the cave were the highest in March 2016 and the lowest in December 2015.The higher particle concentration from March to May was related to the frequent occurrence of sand and dust events,and the lower particle concentration from June to September was associated with good diffusion conditions,increased precipitation,and an established cave shelterbelt.The concentration of particulate matter inside the cave was affected by the concentration of particles in the air outside the cave.Ca2+,NH+4,Na+,Cl-,and SO2-4were the main components of the total ions of PM_(2.5) and PM_(10) both inside and outside the cave.The total ions inside the cave were frequently affected by the disturbance of tourists'activities during the peak tourist season from May to August.Under the influence of dust,the total concentrations of Cl-,SO2-4,Na+,NH+4,and Ca2+in particles of different sizes inside and outside the cave increased,and the concentrations of Cl-,SO2-4,Na+,and Ca2+decreased during precipitation period.Backward air mass trajectory analysis suggested that the pollutants were mainly from Xinjiang,China.The pollutant sources of air particulates are straw burning,secondary pollution sources,soil dust,dry spring rivers,and tourist activities.
基金financially supported by the Major Science and Technology Special Project of Inner Mongolia(Y439K71001)the National Natural Science Foundation of China(1103Y511521,31270501)
文摘Understanding the status and distribution of the micronutrient Zn in soils is important for managing plant growth and preventing soil pollution for agricultural irrigation systems in arid and semi-arid regions.In this study,a total of 195 soil samples from five soil layers(0–20,20–40,40–60,60–80 and 80–100 cm) in the three land-use types(wasteland,forestland and cropland) after long-term agricultural fertilization and irrigation with Yellow River water were collected in the middle of the Hetao oasis,i.e.the Yongji irrigation sub-oasis.We analyzed the vertical and spatial distributions of Zn content and its relationship with soil properties to determine whether differences of Zn content existed in the soil profiles.The results revealed that the mean content of Zn was 107 mg/kg,1.9 times higher than the background value(55.7 mg/kg) of the Hetao oasis and much lower than the secondary standard value(300 mg/kg) of the Chinese Environmental Quality Standard for Soils when p H>7.5.Soil Zn contents were not significantly different and the coefficients of variation of Zn contents were less than 50% in the five soil layers.Soil Zn content was similar from southern to northern parts but increased from western to eastern parts in the sub-oasis.Soil Zn contents did not differ significantly among the three land-use types,but soil total nitrogen(TN) contents were significantly higher in the agriculturally managed forestland and cropland than in the wasteland(P<0.05).Zn was significantly and positively correlated with TN(F=36.6,P<0.001).The use of fertilizers may increase the content of Zn in soils,but flooding irrigation may minimize the differences in the spatial distribution of soil Zn content in the whole sub-oasis.This research is of important value for soil pollution control and sustainable land use management in arid and semi-arid regions.
