黄土高原中国松人工林演替过程中的土壤微生物和酶活性

Successional and seasonal effects on soil microbial and enzymatic properties were studied in Chinese pine (Pinus tabu- laeformis) plantations in an age sequence of 3-, 7-, 13-, 21- and 28-year-old in northern Ziwuling region in the middle of Loess Plateau, China. The results indicated that plantation age and season affected soil microbial and enzymatic parameters significantly. Soil organic C, total N, microbial biomass C, microbial quotient, basal respiration, dehydrogenase, N-α-benzoyl-L-argininamide (BAA)-protease, urease and β-glucosidase increased quickly and tended to be highest at PF21 (21-year plantation), thereafter they remained nearly at a constant level, whereas the metabolic quotient (qCO 2 ) showed an initial increase and then decreased gradually. Measures of these soil properties showed significant seasonal fluctuations except for organic C and total N, which were found to be relatively stable throughout the study period, and the seasonal distributions were autumn spring summer winter for microbial biomass C, microbial quotient, dehydrogenase, and β-glucosidase; autumn summer spring winter for BAA-protease and urease; and summer autumn spring winter for basal respiration and qCO 2 . Significant season × age interaction was observed for biomass C, basal respiration, dehydrogenase and BAA-protease.     

退化喀斯特植被恢复与土壤微生物特征的关系

The mechanism of vegetation restoration on degraded karst regions has been a research focus of soil science and ecology for the last decade.In an attempt to preferably interpret the soil microbiological characteristic variation associated with vegetation restoration and further to explore the role of soil microbiology in vegetation restoration mechanism of degraded karst regions,we measured microbial biomass C and basal respiration in soils during vegetation restoration in Zhenfeng County of southwestern Guizhou Province,China.The community level physiological profiles(CLPP) of the soil microbial community to were estimated determine if vegetation changes were accompanied by changes in functioning of soil microbial communities.The results showed that soil microbial biomass C and microbial quotient(microbial biomass C/organic C) tended to increase with vegetation restoration,being in the order arboreal community stage > shrubby community stage > herbaceous community stage > bare land stage.Similar trend was found in the change of basal respiration(BR).The metabolic quotient(the ratio of basal respiration to microbial biomass,qCO 2) decreased with vegetation restoration,and remained at a constantly low level in the arboreal community stage.Analyses of the CLPP data indicated that vegetation restoration tended to result in higher average well color development,substrate richness,and functional diversity.Average utilization of specific substrate guilds was highest in the arboreal community stage.Principle component analysis of the CLPP data further indicated that the arboreal community stage was distinctly different from the other three stages.In conclusion,vegetation restoration improved soil microbial biomass C,respiration,and utilization of carbon sources,and decreased qCO 2,thus creating better soil conditions,which in turn could promote the restoration of vegetation on degraded karst regions.     

重复添加植物残体后土壤微生物活性和生物量对盐度的响应特征

Microbial adaptation to salinity can be achieved through synthesis of organic osmolytes,which requires high amounts of energy;however,a single addition of plant residues can only temporarily improve energy supply to soil microbes.Therefore,a laboratory incubation experiment was conducted to evaluate the responses of soil microbes to increasing salinity with repeated additions of plant residues using a loamy sand soil with an electrical conductivity in saturated paste extract（EC_e） of 0.6 dS m^-1.The soil was kept non-saline or salinized by adding different amounts of NaCl to achieve EC_e of 12.5,25.0 and 50.0 dS m^-1.The non-saline soil and the saline soils were amended with finely ground pea residues at two rates equivalent to 3.9 and 7.8 g C kg^-1 soil on days 0,15 and29.The soils receiving no residues were included as a control.Cumulative respiration per g C added over 2 weeks after each residue addition was always greater at 3.9 than 7.8 g C kg^-1 soil and higher in the non-saline soil than in the saline soils.In the saline soils,the cumulative respiration per g C added was higher after the second and third additions than after the first addition except with3.9 g C kg^-1 at EC_e of 50 dS m^₁.Though with the same amount of C added(7.8 g C kg^-1),salinity reduced soil respiration to a lesser extent when 3.9 g C kg^-1 was added twice compared to a single addition of 7.8 g C kg^-1.After the third residue addition,the microbial biomass C concentration was significantly lower in the soils with EC_e of 25 and 50 dS m^₁ than in the non-saline soil at3.9 g C kg^-1,but only in the soil with EC_e of 50 dS m^-1 at 7.8 g C kg^-1.We concluded that repeated residue additions increased the adaptation of soil microbial community to salinity,which was likely due to high C availability providing microbes with the energy needed for synthesis of organic osmolytes.     

清水灌溉在消除土壤多环芳烃中的作用及对土壤微生物特征的影响: 以沈抚灌区为例

To evaluate the effect of groundwater irrigation on the polycyclic aromatic hydrocarbons(PAHs) pollution abatement and soil microbial characteristics,a case study was performed in the Shenfu irrigation area of Shenyang,Northeast China,where the irrigation with petroleum wastewater had lasted for more than fifty years,and then groundwater irrigation instead of wastewater irrigation was applied due to the gradually serious PAHs pollution in soil.Soil chemical properties,including PAHs and nutrients contents,and soil microbial characteristics,including microbial biomass carbon,substrateinduced respiration,microbial quotient(qM),metabolic quotient(qCO2),dehydrogenase(DH),polyphenol oxidase(PO),urease(UR) and cellulase(CE) in surface and subsurface were determined.Total organic C,total N,total P,and available K were significantly different between the sites studied.The PAHs concentrations ranged from 610.9 to 6362.8 μg kg-1 in the surface layers(0-20 cm) and from 404.6 to 4318.5 μg kg-1 in the subsurface layers(20-40 cm).From the principal component analysis,the first principal component was primarily weighed by total PAHs,total organic C,total N,total P and available K,and it was the main factor that influencing the soil microbial characteristics.Among the tested microbial characteristics,DH,PO,UR,CE,qM and qCO2 were more sensitive to the PAHs stress than the others,thus they could serve as useful ecological assessment indicators for soil PAHs pollution.     

巴西东北部地区土地退化对土壤微生物量和活性的影响

Land degradation causes great changes in the soil biological properties.The process of degradation may decrease soil microbial biomass and consequently decrease soil microbial activity.The study was conducted out during 2009 and 2010 at the four sites of land under native vegetation(NV),moderately degraded land(LDL),highly degraded land(HDL) and land under restoration for four years(RL) to evaluate changes in soil microbial biomass and activity in lands with different degradation levels in comparison with both land under native vegetation and land under restoration in Northeast Brazil.Soil samples were collected at 0-10 cm depth.Soil organic carbon(SOC),soil microbial biomass C(MBC) and N(MBN),soil respiration(SR),and hydrolysis of fluorescein diacetate(FDA) and dehydrogenase(DHA) activities were analyzed.After two years of evaluation,soil MBC,MBN,FDA and DHA had higher values in the NV,followed by the RL.The decreases of soil microbial biomass and enzyme activities in the degraded lands were approximately 8-10 times as large as those found in the NV.However,after land restoration,the MBC and MBN increased approximately 5-fold and 2-fold,respectively,compared with the HDL.The results showed that land degradation produced a strong decrease in soil microbial biomass.However,land restoration may promote short-and long-term increases in soil microbial biomass.     

温度和秸秆质量调节与秸秆分解相关的微生物磷脂脂肪酸（PLFA）组成

Variations in temperature and moisture play an important role in soil organic matter (SOM) decomposition. However, relationships between changes in microbial community composition induced by increasing temperature and SOM decomposition are still unclear. The present study was conducted to investigate the effects of temperature and moisture levels on soil respiration and microbial communities involved in straw decomposition and elucidate the impact of microbial communities on straw mass loss. A 120-d litterbag experiment was conducted using wheat and maize straw at three levels of soil moisture (40%, 70%, and 90% of water-holding capacity) and temperature (15, 25, and 35°C). The microbial communities were then assessed by phospholipid fatty acid (PLFA) analysis. With the exception of fungal PLFAs in maize straw at day 120, the PLFAs indicative of Gram-negative bacteria and fungi decreased with increasing temperatures. Temperature and straw C/N ratio significantly affected the microbial PLFA composition at the early stage, while soil microbial biomass carbon (C) had a stronger effect than straw C/N ratio at the later stage. Soil moisture levels exhibited no significant effect on microbial PLFA composition. Total PLFAs significantly influenced straw mass loss at the early stage of decomposition, but not at the later stage. In addition, the ratio of Gram-negative and Gram-positive bacterial PLFAs was negatively correlated with the straw mass loss. These results indicated that shifts in microbial PLFA composition induced by temperature, straw quality, and microbial C sources could lead to changes in straw decomposition.     

Pb-Zn交互作用对红壤微生物生物量的影响

A laboratory incubation experiment was conducted to evaluate the effects of lead and zinc applied alone or in various combinations on the size of microbial biomass in a red soil. Treatments included the application of lead at six different levels i. e., 0 (background), 100, 200, 300, 450 and 600 g g^-1 soil along with each of the four levels of zinc (0, 50, 150 or 250 g g^-1 soil). Application of lead or zinc alone to soil significantly (P < 0. 001) affected the soil microbial biomass. The microbial biomass carbon (C_mic), biomass nitrogen (N_mic) and biomass phosphorus (P_mic) decreased sharply in soils contaminated with lead or zinc. Combined application of lead and zinc resulted in a greater biocidal effect on soil microbial biomass, which was significantly higher (P < 0. 001) than that when either lead or zinc was applied alone. Consistent increase in the biomass C: N and decline in the biomass C:P ratios were also observed with the increased metal (Pb and Zn) toxicity in the soil.     

黄土高原某些耕作土壤中土壤微生物生物量C、N与矿化N的关系

The chloroform fumigation-incubation method was used to measure the soil microbial biomass C (SMBC) and N (SMBN) in 16 loessial soils sampled from Ansai, Yongshou and Yangling in Shaanxi Province. The SMBC contents in the soils ranged from 75.9 to 301.0 μg C g^-1 with an average of 206.1 μg C g^-1, accounting for 1.36%~6.24% of the total soil organic C with an average of 3.07%, and the SMBN contents from 0.51 to 68.40 μg N g^-1 with an average of 29.4 μg N g^-1, accounting for 0.20%~5.65% of the total N in the soils with an average of 3.36%. A close relationship was found between SMBC and SMBN, and they both were positively correlated with total organic C, total N, NaOH hydrolizable N and mineralizable N. These results confirmed that soil microbial biomass had a comparative role in nutrient cycles of soils.     

中国土壤微生物量的大小

The microbial biomass C, N and P of soils all over China were determined in this study to study their affecting factors. The results, about 100-417 mg C kg^-1 soil, 18-51 mg N kg^-1 soil and 4.4-27.3 mg P kg^-1 soil, showed the biomass C, N and P in linear relationship with the soil total organic C, toal N and soil organic P. The ratios of C: N and C:P, ranging from 5.6 to 9.6 and from 11.2 to 48.4 respectively, were affected by soil pH, texture, crop rotation, macroclimate, etc. The ratio of C:N in soil biomass increases gradually from the north to the south in China.     

传统耕作和覆盖作物管理方式下半干旱区葡萄园表层土壤性质影响降水后碳氧化物排放

In semiarid regions of the Mediterranean basin, a rainfall event can induce a respiratory pulse that releases a large amount of soil carbon dioxide(CO_2) into the atmosphere; this pulse can significantly contribute to the annual ecosystem carbon(C) balance.The impacts of conventional tillage and two different cover crops, resident vegetation and Bromus catharticus L., on soil CO_2 efflux were evaluated in a Vitis vinifera L. vineyard in La Rioja, Spain. Soil CO_2 efflux, gravimetric water content, and temperature were monitored at a depth of 0–5 cm after rainfall precipitation events approximately every 10 d in the period from May 17 to July 27, 2012,during which the cover crops had withered. Additionally, on June 10, 2012, soil organic C, microbial biomass C, and β-glucosidase activity were determined at soil depths of 0–2.5, 2.5–5, 5–15, and 15–25 cm. The results show that pulses of soil CO_2 were related to the increase in soil water content following precipitation events. Compared to the conventional tillage treatment, both cover crop treatments had higher soil CO_2 efflux after precipitation events. Both cover crop treatments had higher soil organic C, microbial biomass C, and β-glucosidase activity at the soil surface(0–2.5 cm) than the conventional tillage treatment. Each pulse of CO_2 was related to the surface soil properties. Thus, this study suggests that the enhancement of soil organic C and microbiological properties at the soil surface under cover crops may increase soil CO_2 efflux relative to conventional tillage immediately after precipitation events during the dry season.     

多氯联苯污染土壤的微生物生态效应研究

以多氯联苯（Polychlorinated biphenyls,PCBs）自然污染的农田土壤为材料,分析土壤中微生物区系组成、生物量C、N、土壤基础呼吸以及微生物群落功能多样性的变化。研究结果表明,在以4-氯、5-氯同系物为主的PCBs污染土壤中,污染程度对土壤细菌、放线菌的数量影响不明显,而真菌的数量除与土壤污染程度有关,可能还受到土壤pH等性状的影响;土壤微生物C、N与土壤基础呼吸随污染程度的加剧呈下降趋势,但微生物C／N基本没有变化;Biolog分析显示,土壤微生物代谢剖面（AWCD）及Simpson指数在污染程度相差较大的两组土壤样品中差异均达到了显著性水平,表明PCBs污染引起了土壤微生物群落功能多样性下降,降低了微生物对不同单一碳源底物的利用能力。     

沙漠系统中豆类作物根际附近区域土壤微生物群落研究

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.     

铅污染对青紫泥微生物活性的影响

土壤微生物量碳、基础呼吸作用、土壤代谢商是表征土壤质量的重要指标,并且与土壤本身的理化性质有关。脱氢酶活性是土壤微生物种群及其活性的重要敏感性指标之一。通过室内培养,研究了不同铅添加水平(200~1 200 mg/kg)对青紫泥田微生物生物量碳及土壤基础呼吸作用、土壤代谢商、土壤脱氢酶的影响。研究表明:随培养时间延长,青紫泥田生物量碳呈下降趋势,基础呼吸作用随铅浓度升高而加强。土壤代谢商随培养时间延长变化趋势不同。外源铅胁迫下土壤脱氢酶活性随铅处理浓度升高明显受抑制。相关分析表明,土壤铅含量与土壤微生物生物量碳、脱氢酶在不同培养时期相关性不同。     

喀斯特峡谷区不同恢复阶段土壤微生物量及呼吸商

土壤微生物生物量、土壤微生物呼吸及微生物商值（微生物商qMB、微生物呼吸商qCO2）是土壤质量的敏感性指标。对喀斯特峡谷区不同植被恢复阶段土壤微生物生物量、土壤微生物呼吸及其qMB、qCO2进行研究,结果表明：在植被恢复过程中,土壤微生物生物量、土壤微生物呼吸及qMB均表现为从退耕地到草本群落下降,从草本到灌木群落上升,从灌木到乔木群落略微上升或者趋于稳定;qCO2的变化规律与它们相反。在同一恢复阶段,土壤微生物生物量,土壤微生物呼吸,qMB值均随土层加深而减小。土壤微生物生物量、微生物呼吸及其qMB、qCO2与土壤总有机碳、全氮、全磷具有显著的线性相关关系（p〈0.05）,可用来评价土壤质量。     

土地耕作后微生物量碳和水溶性有机碳的动态特征

采用野外观测与室内模拟试验相结合的方法,研究了湿地土壤和垦殖10年的农田耕作后土壤呼吸通量、微生物量碳、土壤基础呼吸、土壤qCO2值、水溶性有机碳的动态特征。研究结果表明:小叶章湿地耕作后,土壤含水量明显下降(p<0.05);土壤CO2通量在最初的1~2 d形成一个排放高峰,农田耕作土壤CO2通量一直显著高于未耕作土壤(p<0.01)。农田土壤微生物量碳含量显著低于小叶章湿地(p<0.001)。在耕作后最初的1~3 d,湿地和农田土壤微生物量碳均没有显著的变化;之后,土壤微生物量碳迅速增加,显著高于未耕作土壤。观测时间内,耕作农田土壤微生物量碳含量始终显著高于未耕作土壤(p<0.01)。垦殖10年农田土壤耕作后,对土壤水溶性有机碳含量无显著影响。湿地耕作后,土壤水溶性有机碳迅速增加。在耕作后80 d内,土壤水溶性有机碳含量显著高于未耕作土壤(p<0.01)。之后,则低于未耕作土壤。