Land use changes are known to alter soil organic carbon （SOC） and microbial properties, however, information about how conversion of natural forest to agricultural land use as well as plantations affects SOC and mic...Land use changes are known to alter soil organic carbon （SOC） and microbial properties, however, information about how conversion of natural forest to agricultural land use as well as plantations affects SOC and microbial properties in the Changbai Moun- tains of Northeast China is meager. Soil carbon content, microbial biomass carbon （MBC）, basal respiration and soil carbon mineraliza- tion were studied in five selected types of land use： natural old-growth broad-leaved Korean pine mixed forest （NF）; spruce plantation （SP） established following clear-cutting of NF; cropland （CL）; ginseng farmland （GF） previously under NF; and a five-year Mongolian oak young forest （YF） reforested on an abandoned GF, in the Changbai Mountains of Northeast China in 2011. Results showed that SOC content was significantly lower in SP, CL, GF, and YF than in NF. MBC ranged from 304.4 mg/kg in CL to 1350.3 mg/kg in NF, which was significantly higher in the soil of NF than any soil of the other four land use types. The SOC and MBC contents were higher in SP soil than in CL, GF, and YF soils, yielding a significant difference between SP and CL. The value of basal respiration was also higher in NF than in SP, CL, GF, and YF. Simultaneously, higher values of the metabolic quotient were detected in CL, GF, and YF soils, indicat- ing low substrate utilization of the soil microbial community compared with that in NF and SP soil. The values of cumulative mineral- ized carbon and potentially mineralized carbon （Co） in NF were significantly higher than those in CL and GF, while no significant dif- ference was observed between NF and SP. In addition, YF had higher values of Co and C mineralization rate compared with GF. The results indicate that conversion from NF into agricultural land （CL and GF） uses and plantation may lead to a reduction in soil nutrients （SOC and MBC） and substrate utilization efficiency of the microbial community. By contrast, soils below SP were more conducive to the preservation of soil organic matter, which was reflected in the comparison of microbial indicators among CL, GF, and YF land uses. This study can provide data for evaluating soils nutrients under different land use types, and serve as references for the rational land use of natural forest in the study area.展开更多
The effects of salinity on soil organic carbon （SOC） and its labile fractions including microbial biomass carbon （MBC） and easily oxidation organic carbon （EOC）, basal soil respiration, and soil nematode communi...The effects of salinity on soil organic carbon （SOC） and its labile fractions including microbial biomass carbon （MBC） and easily oxidation organic carbon （EOC）, basal soil respiration, and soil nematode community in the Fluvents, an oasis in an arid region of northwestern China were investigated. Five sites were selected which had a salinity gradient with different groundwater table from 1.0 m to 4.0 m. Soils were sampled at the 0~0 cm plough layer from 25 irrigated fields of five sites and electrical conductivity was measured in the saturation paste extracts （ECe）. Soils were categorized into five salinity levels： （1） non-saline, （2） very slightly saline, （3） slightly saline, （4） moderately saline, and （5） strongly saline according to the values of ECe. The results show that SOC and total nitrogen concentration, cation exchange capacity （CEC）, and the concentrations of labile organic fractions （MBC, EOC）, and basal soil respiration decreased significantly with increasing ECe. The relationships between ECe and MBC, EOC and basal soil respiration were best described by power functions. Slight and moderate salinity had no significant impact on soil nematode abundance, but excessive salt accumulation led to a marked decline in soil nematode community diversity and abundance. Soil salinity changed soil nematode trophic groups and bacterivores were the most abundant trophic groups in salt-affected soils. Further study is necessary to identify the response of soil microbial processes and nematode community dynamics to soil salinity.展开更多
Elevated atmospheric CO2 can influence soil C dynamics in agroecosystems. The effects of free-air CO2 enrichment （FACE） and N fertilization on soil organic C （Corg）, dissolved organic C （DOC）, microbial biomass...Elevated atmospheric CO2 can influence soil C dynamics in agroecosystems. The effects of free-air CO2 enrichment （FACE） and N fertilization on soil organic C （Corg）, dissolved organic C （DOC）, microbial biomass C （Cmic） and soil basal respiration （SBR） were investigated in a Chinese wheat field after expose to elevated CO2 for four full years. The results indicated that elevated CO2 has stimulative effects on soil C concentrations regardless of N fertilization. Following the elevated CO2, the concentrations of Corg and SBR were increased at wheat jointing stage, and those of DOC and Cmic were enhanced obviously across the wheat jointing stage and the fallow period after wheat harvest. On the other hand, N fertilization did not significantly affect the content of soil C. Significant correlations were found among DOC, Cmic, and SBR in this study.展开更多
Cadmium (Cd) is ubiquitous in the human environment and has toxic effect on soil microbial biomass or its activity, including microbial biomass carbon (Cmic), dehydrogenase activity (DHA) and basal respiration (BR), e...Cadmium (Cd) is ubiquitous in the human environment and has toxic effect on soil microbial biomass or its activity, including microbial biomass carbon (Cmic), dehydrogenase activity (DHA) and basal respiration (BR), etc., Cmic, DHA, BR were used as bioindicators of the toxic effect of Cd in soil. This study was conducted to determine the effects of Cd on soil microbial biomass and its activity in a paddy soil. The inhibition of microbial biomass and its activity by different Cd concentrations was described by the kinetic model (M1) and the sigmoid dose-response model (M2) in order to calculate three ecological doses of Cd: ED50, ED10 and ED5. Results showed that M2 was better fit than M1 for describing the ecological toxicity dose effect of cadmium on soil microbial biomass and its activity in a paddy soil. M2 for ED values (mg/kg soil) of Cmic, DHA, BR best fitted the measured paddy soil bioindicators. M2 showed that all ED values (mg/kg) increased in turn with increased incubation time. ED50, ED10 and ED5 of Cmic with M2 were increased in turn from 403.2, 141.1, 100.4 to 1000.7, 230.9, 144.8, respectively, after 10 d to 60 d of incubation. ED50, ED10 and ED5 of DHA with M2 increased in turn from 67.6, 6.2, 1.5 to 101.1, 50.9, 41.0, respectively, after 10 d to 60 d of incubation. ED50, ED10 and ED5 of BR with M2 increased in turn from 149.7, 6.5, 1.8 to 156.5, 50.8, 35.5, respectively, after 10 d to 60 d of incubation. So the ecological dose increased in turn with increased incubation time for M2 showed that toxicity of cadmium to soil microbial biomass and its activity was decreased with increased incubation time.展开更多
The aim of the current study was to gain a better understanding of the changes in soil microbial biomass and basal respiration dynamics in the vicinity of the bean caper （Zygophyllura duraosura） perennial desert shr...The aim of the current study was to gain a better understanding of the changes in soil microbial biomass and basal respiration dynamics in the vicinity of the bean caper （Zygophyllura duraosura） perennial desert shrub and the inter-shrub sites. Microbial biomasses as well as basal respiration were found to be significantly greater in the soil samples taken beneath the Z. duraosura shrubs than from the inter-shrub sampling sites, with no differences between the two sampling layers （0-10 and 10-20 cm） throughout the study period. However, seasonal changes were observed due to autumn dew formation, which significantly affected microbial biomass and basal respiration in the upper-layer inter-shrub locations. The calculated metabolic coefficient （qCO2） revealed significant differences between the two sampling sites as well as between the two soil layers, elucidating the abiotic effect between the sites throughout the study period. The substrate availability index was found to significantly demonstrate the differences between the two sites, elucidating the significant contribution of Z. duraosura in food source availability and in moderating harsh abiotic components. The importance of basal microbial parameters and the derived indices as tools demonstrated the importance and need for basic knowledge in understanding plant-soil interactions determined by an unpredictable and harsh desert environment.展开更多
Microbiological and physical\|chemical characteristics of subtropical forest, grassland and cropfield soils from the karst areas of Southwest China were investigated. The study revealed that the conversion of natural ...Microbiological and physical\|chemical characteristics of subtropical forest, grassland and cropfield soils from the karst areas of Southwest China were investigated. The study revealed that the conversion of natural forest to other forms of land would lead to a reduction in soil organic C(26.2%-35.3%), total N(37.2%-55.8%), total P(32.9%-43.6%), microbial biomass C(35.4%-49.1%), N(37.2%-55.8%), and P(25.8%-41.9%). Comparative analysis of microbial activity in terms of basal soil respiration showed maximum activity in forest soil and minimum in cropfield soil. Analysis of microbial metabolic respiratory activity indicated a relatively greater respiratory loss of CO\-2—C per unit microbial biomass in cropfield and grassland than in forest soil. Considering the importance of microbial components in soil, it is concluded that land use in different ways will lead to the reduction of biological stability of soil.展开更多
基金Under the auspices of National Key Technology Research and Development Program of China(No.2012BAD22B04)CFERN&GENE Award Funds on Ecological PaperNational Natural Science Foundation of China(No.30900208)
文摘Land use changes are known to alter soil organic carbon （SOC） and microbial properties, however, information about how conversion of natural forest to agricultural land use as well as plantations affects SOC and microbial properties in the Changbai Moun- tains of Northeast China is meager. Soil carbon content, microbial biomass carbon （MBC）, basal respiration and soil carbon mineraliza- tion were studied in five selected types of land use： natural old-growth broad-leaved Korean pine mixed forest （NF）; spruce plantation （SP） established following clear-cutting of NF; cropland （CL）; ginseng farmland （GF） previously under NF; and a five-year Mongolian oak young forest （YF） reforested on an abandoned GF, in the Changbai Mountains of Northeast China in 2011. Results showed that SOC content was significantly lower in SP, CL, GF, and YF than in NF. MBC ranged from 304.4 mg/kg in CL to 1350.3 mg/kg in NF, which was significantly higher in the soil of NF than any soil of the other four land use types. The SOC and MBC contents were higher in SP soil than in CL, GF, and YF soils, yielding a significant difference between SP and CL. The value of basal respiration was also higher in NF than in SP, CL, GF, and YF. Simultaneously, higher values of the metabolic quotient were detected in CL, GF, and YF soils, indicat- ing low substrate utilization of the soil microbial community compared with that in NF and SP soil. The values of cumulative mineral- ized carbon and potentially mineralized carbon （Co） in NF were significantly higher than those in CL and GF, while no significant dif- ference was observed between NF and SP. In addition, YF had higher values of Co and C mineralization rate compared with GF. The results indicate that conversion from NF into agricultural land （CL and GF） uses and plantation may lead to a reduction in soil nutrients （SOC and MBC） and substrate utilization efficiency of the microbial community. By contrast, soils below SP were more conducive to the preservation of soil organic matter, which was reflected in the comparison of microbial indicators among CL, GF, and YF land uses. This study can provide data for evaluating soils nutrients under different land use types, and serve as references for the rational land use of natural forest in the study area.
基金supported by the National Natural Science Foundation of China(91425302,41401337)
文摘The effects of salinity on soil organic carbon （SOC） and its labile fractions including microbial biomass carbon （MBC） and easily oxidation organic carbon （EOC）, basal soil respiration, and soil nematode community in the Fluvents, an oasis in an arid region of northwestern China were investigated. Five sites were selected which had a salinity gradient with different groundwater table from 1.0 m to 4.0 m. Soils were sampled at the 0~0 cm plough layer from 25 irrigated fields of five sites and electrical conductivity was measured in the saturation paste extracts （ECe）. Soils were categorized into five salinity levels： （1） non-saline, （2） very slightly saline, （3） slightly saline, （4） moderately saline, and （5） strongly saline according to the values of ECe. The results show that SOC and total nitrogen concentration, cation exchange capacity （CEC）, and the concentrations of labile organic fractions （MBC, EOC）, and basal soil respiration decreased significantly with increasing ECe. The relationships between ECe and MBC, EOC and basal soil respiration were best described by power functions. Slight and moderate salinity had no significant impact on soil nematode abundance, but excessive salt accumulation led to a marked decline in soil nematode community diversity and abundance. Soil salinity changed soil nematode trophic groups and bacterivores were the most abundant trophic groups in salt-affected soils. Further study is necessary to identify the response of soil microbial processes and nematode community dynamics to soil salinity.
基金supported by the National Natural Science Foundation of China(No.30770400,40231003)the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-408)
文摘Elevated atmospheric CO2 can influence soil C dynamics in agroecosystems. The effects of free-air CO2 enrichment （FACE） and N fertilization on soil organic C （Corg）, dissolved organic C （DOC）, microbial biomass C （Cmic） and soil basal respiration （SBR） were investigated in a Chinese wheat field after expose to elevated CO2 for four full years. The results indicated that elevated CO2 has stimulative effects on soil C concentrations regardless of N fertilization. Following the elevated CO2, the concentrations of Corg and SBR were increased at wheat jointing stage, and those of DOC and Cmic were enhanced obviously across the wheat jointing stage and the fallow period after wheat harvest. On the other hand, N fertilization did not significantly affect the content of soil C. Significant correlations were found among DOC, Cmic, and SBR in this study.
基金Projects supported by the National Basic Research Program (973) ofChina (No. 2002CB410804) and the National Natural Science Foun-dation (No. 40201026) of China
文摘Cadmium (Cd) is ubiquitous in the human environment and has toxic effect on soil microbial biomass or its activity, including microbial biomass carbon (Cmic), dehydrogenase activity (DHA) and basal respiration (BR), etc., Cmic, DHA, BR were used as bioindicators of the toxic effect of Cd in soil. This study was conducted to determine the effects of Cd on soil microbial biomass and its activity in a paddy soil. The inhibition of microbial biomass and its activity by different Cd concentrations was described by the kinetic model (M1) and the sigmoid dose-response model (M2) in order to calculate three ecological doses of Cd: ED50, ED10 and ED5. Results showed that M2 was better fit than M1 for describing the ecological toxicity dose effect of cadmium on soil microbial biomass and its activity in a paddy soil. M2 for ED values (mg/kg soil) of Cmic, DHA, BR best fitted the measured paddy soil bioindicators. M2 showed that all ED values (mg/kg) increased in turn with increased incubation time. ED50, ED10 and ED5 of Cmic with M2 were increased in turn from 403.2, 141.1, 100.4 to 1000.7, 230.9, 144.8, respectively, after 10 d to 60 d of incubation. ED50, ED10 and ED5 of DHA with M2 increased in turn from 67.6, 6.2, 1.5 to 101.1, 50.9, 41.0, respectively, after 10 d to 60 d of incubation. ED50, ED10 and ED5 of BR with M2 increased in turn from 149.7, 6.5, 1.8 to 156.5, 50.8, 35.5, respectively, after 10 d to 60 d of incubation. So the ecological dose increased in turn with increased incubation time for M2 showed that toxicity of cadmium to soil microbial biomass and its activity was decreased with increased incubation time.
文摘The aim of the current study was to gain a better understanding of the changes in soil microbial biomass and basal respiration dynamics in the vicinity of the bean caper （Zygophyllura duraosura） perennial desert shrub and the inter-shrub sites. Microbial biomasses as well as basal respiration were found to be significantly greater in the soil samples taken beneath the Z. duraosura shrubs than from the inter-shrub sampling sites, with no differences between the two sampling layers （0-10 and 10-20 cm） throughout the study period. However, seasonal changes were observed due to autumn dew formation, which significantly affected microbial biomass and basal respiration in the upper-layer inter-shrub locations. The calculated metabolic coefficient （qCO2） revealed significant differences between the two sampling sites as well as between the two soil layers, elucidating the abiotic effect between the sites throughout the study period. The substrate availability index was found to significantly demonstrate the differences between the two sites, elucidating the significant contribution of Z. duraosura in food source availability and in moderating harsh abiotic components. The importance of basal microbial parameters and the derived indices as tools demonstrated the importance and need for basic knowledge in understanding plant-soil interactions determined by an unpredictable and harsh desert environment.
文摘Microbiological and physical\|chemical characteristics of subtropical forest, grassland and cropfield soils from the karst areas of Southwest China were investigated. The study revealed that the conversion of natural forest to other forms of land would lead to a reduction in soil organic C(26.2%-35.3%), total N(37.2%-55.8%), total P(32.9%-43.6%), microbial biomass C(35.4%-49.1%), N(37.2%-55.8%), and P(25.8%-41.9%). Comparative analysis of microbial activity in terms of basal soil respiration showed maximum activity in forest soil and minimum in cropfield soil. Analysis of microbial metabolic respiratory activity indicated a relatively greater respiratory loss of CO\-2—C per unit microbial biomass in cropfield and grassland than in forest soil. Considering the importance of microbial components in soil, it is concluded that land use in different ways will lead to the reduction of biological stability of soil.
文摘选取广西环江县喀斯特峰丛洼地:草丛(T)、灌丛(S)、原生林(PF)(中坡位)不同植被类型,原生林上、中、下不同坡位,按土壤发生层采集淋溶层(A层,0—10 cm)、过渡层(AB层,20—30 cm,草丛和灌丛;30—50 cm,原生林)、淀积层(B层,70—100cm)样品,研究土壤微生物量碳、氮(Soil microbial biomass carbon(SMBC)、soil microbial biomass nitrogen(SMBN))、微生物碳熵、氮熵(ratio of SMBC to soil organic carbon(qMBC)、ratio of SMBN to soil total nitrogen(qMBN))、土壤基础呼吸(soil basicrespiration(SBR))以及代谢熵(microbial metabolic quotient(qCO2))的剖面分异特征及其影响因素。结果表明,植被、土层深度显著影响土壤微生物量及基础呼吸,随植被恢复,SMBC、SMBN、SBR由草丛、灌丛、原生林依次上升,并随土壤发生层位的加深逐渐减少,qCO2在3种植被类型间差异显著:T>PF>S;原生林A层SMBC,SMBN在各坡位间均显著高于AB层、B层,SBR在A层由下坡位至上坡位递减,而在AB和B层的上、下坡位间无显著差异,qCO2坡位间无显著差异(P>0.05);SMBC与SMBN之间存在显著正相关(r=0.825,P<0.01,n=45),且SMBC、SMBN、SBR分别与有机碳、全氮、碱解氮均呈显著正相关。因此,随植被恢复,土壤质量明显改善,且坡位对A层土壤的影响较AB层和B层更显著,对于维持土壤微生物调节的土壤养分循环功能,调控土壤氮素营养与土壤有机质同等重要,这为合理制订喀斯特生态恢复措施提供了理论依据。
