Land use effects on soil organic carbon,microbial biomass and microbial activity in Changbai Mountains of Northeast China   总被引：2，自引：0，他引：2  

Xiangmin Fang  Qingli Wang  Wangming Zhou  Wei Zhao  Yawei Wei  Lijun Niu  Limin Dai 《中国地理科学(英文版)》2014,24(3):297-306

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.  相似文献   

The Soil Moisture and Net Primary Production Affected by CO_2 and Climate Change Using a Coupled Model          下载免费PDF全文

PENG Jing  DAN Li 《大气和海洋科学快报》2014,(4):269-274

In this paper, a coupled model was used to estimate the responses of soil moisture and net primary production of vegetation （NPP） to increasing atmospheric CO2 concentration and climate change. The analysis uses three experiments simulated by the second-generation Earth System Model （CanESM2） of the Canadian Centre for Climate Modelling and Analysis （CCCma）, which are part of the phase 5 of the Coupled Model Intercomparison Project （CMIP5）. The authors focus on the magnitude and evolution of responses in soil moisture and NPP using simulations modeled by CanESM, in which the individual effects of increasing CO2 concentration and climate change and their combined effect are separately accounted for. When considering only the single effect of climate change, the soil moisture and NPP have a linear trend of 0.03 kg m^-2 yr^-1 and-0.14 gC m^- 2 yr^-2, respec- tively. However, such a reduction in the global NPP results from the decrease of NPP at lower latitudes and in the Southern Hemisphere, although increased NPP has been shown in high northern latitudes. The largest negative trend is located in the Amazon basin at -1.79 gC m^-2 yr^-2. For the individual effect of increasing CO2 concentration, both soil moisture and NPP show increases, with an elevated linear trend of 0.02 kg m^-2 yr^-1 and 0.84 gC m^-2 yr^-2, respectively. Most regions show an increasing NPP, except Alaska. For the combined effect of increasing atmospheric CO2 and climate change, the increased soil moisture and NPP exhibit a linear trend of 0.04 kg m^2 yr^-1 and 0.83 gC m^2 yr^-2 at a global scale. In the Amazon basin, the higher reduction in soil moisture is illustrated by the model, with a linear trend of-0.39 kg m^-2 yr^-1, for the combined effect. Such a change in soil moisture is caused by a weakened Walker circulation simulated by this coupled model, compared with the single effect of increasing CO2 concentration （experiment M2）, and a consequence of the reduction in NPP is also shown in this area, with a linear trend of-  相似文献   

分段多项式拟合在动三轴试验数据处理中的应用     

周松望  周杨锐  吴海京  戴少军  沈志明  董明明 《海洋学报》2014,36(5):186-189

动三轴采集的试验数据点(剪应变与动剪模量和阻尼比之间)具有离散性和有限性,为方便应用需要对数据点进行拟合,但现有经验公式不一定很好吻合试验数据。为得到不同剪应变与对应的动剪模量和阻尼比之间的关系,本文利用最小二乘原理,对渤海某海洋平台地基土进行动三轴试验获得的动剪模量、阻尼比与剪切应变的数据进行了分段多项式的拟合。数据处理过程是先对剪应变值进行了压缩处理,然后再分段低次多项式拟合,得到多项式拟合参数。通过此项改进解决了正规方程解中的病态问题,且拟合效果良好。  相似文献   

不同土壤水分对向日葵光合光响应的影响   总被引：3，自引：0，他引：3       下载免费PDF全文

云文丽  侯琼  王海梅  李建军  张超 《应用气象学报》2014,25(4):476-482

以食用向日葵为试验材料,大田试验采取人为控制土壤水分在胁迫、适宜和过湿 (土壤田间持水量的40%~54.9%,55%~69.9%和70%~90%) 条件下,研究了向日葵3个生育期 (二对真叶—花序形成期、花序形成—开花期、开花—成熟期) 的光合光响应特性。结果表明:在试验设置光强条件下,各生育期净光合速率随着光合有效辐射的增加而增加,同等的光合有效辐射下净光合速率也随着土壤水分的减少依次降低,尤其是随着光合有效辐射的增大愈加明显。土壤湿度对最大净光合速率和表观量子效率的影响并不是同步的,最大净光合速率随着土壤湿度的增加而增大,而表观量子效率在一定程度的水分胁迫情况下出现最大值。不同的土壤水分含量对光补偿点和光饱和点影响不同,光饱和点随着土壤水分的增加而增加,光补偿点却相反,表明水分胁迫使向日葵可利用光的范围缩小,而适宜水分则扩大了光的利用范围,更有利于干物质积累。暗呼吸速率随着植物的生长进程逐渐降低,不同生育期的水分胁迫均导致暗呼吸速率降低。  相似文献   

A Review of Aerosol Optical Properties and Radiative Effects          下载免费PDF全文

LIU Yuzhi  JIA Rui  DAI Tie  XIE Yongkun  SHI Guangyu 《Acta Meteorologica Sinica》2014,28(6):1003-1028

Atmospheric aerosols influence the earth's radiative balance directly through scattering and absorbing solar radiation, and indirectly through affecting cloud properties. An understanding of aerosol optical properties is fundamental to studies of aerosol effects on climate. Although many such studies have been undertaken, large uncertainties in describing aerosol optical characteristics remain, especially regarding the absorption properties of different aerosols. Aerosol radiative effects are considered as either positive or negative perturbations to the radiation balance, and they include direct, indirect (albedo effect and cloud lifetime effect), and semi-direct effects. The total direct effect of anthropogenic aerosols is negative (cooling), although some components may contribute a positive effect (warming). Both the albedo effect and cloud lifetime effect cool the atmosphere by increasing cloud optical depth and cloud cover, respectively. Absorbing aerosols, such as carbonaceous aerosols and dust, exert a positive forcing at the top of atmosphere and a negative forcing at the surface, and they can directly warm the atmosphere. Internally mixed black carbon aerosols produce a stronger warming effect than externally mixed black carbon particles do. The semi-direct effect of absorbing aerosols could amplify this warming effect. Based on observational (ground-and satellite-based) and simulation studies, this paper reviews current progress in research regarding the optical properties and radiative effects of aerosols and also discusses several important issues to be addressed in future studies.  相似文献   

2021年夏季中国大陆涝渍灾害时空分布分析     

李梦倩  房世波  朱永超  武英洁  曹云  卓文  俄有浩 《遥感学报》2022,26(9):1886-1894

涝渍害是中国除干旱以外对农作物影响最严重的气象灾害,涝渍害的发生和发展对人民的生命和财产安全以及农作物的生长发育产生巨大的影响。2021年7月至8月间,中国北方多地降水达到历史观测极值,而相应时期地面的涝渍害发生和发展状况及其时空特征并未得到有效研究。因此,本研究首先利用中国大陆土壤水分站点日数据和被动微波遥感卫星SMAP反演土壤水分日产品获取中国高精度表层土壤湿度数据（0—10 cm）;随后,结合田间持水量数据计算土壤表层相对含水量。在此基础上,以连续10 d土壤相对含水量大于等于90%为标准,分析中国大陆2021年7月1日—8月25日的涝渍害时空分布情况。结果表明：（1）融合后的土壤水分产品较原始的SMAP微波土壤水分产品精度具有明显的提高;（2）中国东北地区水稻田种植区的土壤相对含水量大于等于90%的最长持续天数均为56 d,土壤的水分长期处于饱和状态,说明了本文方法能够较为准确的反应出土壤涝渍害的情况;（3）中国东北及华北地区受灾较为严重,其中黑龙江的西部和河北、河南、山东发生的涝渍面积最大。中国大陆耕地部分受涝渍灾害区域占到总耕地面积的1/2左右,重灾区面积为1.940×10⁵ km²;（4）黑龙江的西部及河北、河南、山东等地较往年降水偏多,这与涝渍害受灾区基本吻合。  相似文献   

长白山区暗棕壤成土作用地球化学特征     

田密  王志华  白荣杰  孙淑梅  王大勇 《世界地质》2014,33(3):695-701

以代表性暗棕壤垂直剖面土壤地球化学数据为依据,研究了长白山区特定的森林景观条件下成土过程中元素的分异与富集特征。研究结果表明,在岩石风化过程中主要以CaO、Na2O、Sr淋溶为主,有机酸淋溶过程中SiO2、Al2O3、K2O部分被淋溶,部分游离铁下渗到土体中下部氧化成铁锰胶膜;微量元素在风化过程中被次生黏土矿物吸附,不同程度地富集,在腐殖质积累过程中Cd、Zn、Pb、Mo、Hg、Co、Mn、Cr等亲生物元素进一步富集于表层土壤,Ce、Ni、Sb、Ti、V、Y、Zr在表生环境中地球化学性质稳定,残留富集于土壤表层。母质层继承和保留了基岩元素地球化学分布的基本特征。  相似文献   

花岗岩类土质边坡工程特性及加固方法研究     

熊自英  黄少强  胡厚田 《工程地质学报》2014,22(6):1241-1249

华南、华东南地区具有厚度可达上百米的花岗岩风化残积层。高等级公路、铁路的规模建设在该地区形成了大量的花岗岩类土质高边坡。深入认识该类边坡的工程特性并提出有效的针对性边坡加固方法,对该地区公路、铁路的安全建设和正常运营具有重要意义。为了更有效指导该类边坡的稳定性分析及边坡设计,本文深入调查分析了广东和广西境内4条高等级公路沿线的44处花岗岩类土质边坡特征及其稳定性,认为控制该类边坡稳定性的因素主要有:土体的均匀性、岩脉(墙)及花岗岩球状硬核的分布情况、坡体中保留的结构面是否对坡体稳定性起控制作用。继而依据这些因素把花岗岩类土质边坡划分为岩脉(墙)隔挡型边坡、网状结构型边坡、外倾结构型边坡、浮石型边坡4种类型。深入分析了每种类型边坡的坡体结构特征、稳定特性,针对性地提出了边坡稳定性分析中应重点考虑的因素。认为花岗岩类土质边坡的土质及坡体结构特征,造成了该类边坡开挖临时自稳性较好,但具有较强的开挖卸荷效应和较弱的抗冲刷能力。最后针对每种类型的花岗岩类土质边坡,提出了相应的设计方案建议。基于花岗岩类土质边坡良好的临时自稳性,认为可进行陡开挖强支护设计,同时强调逐级开挖逐级支护、加强坡面防冲刷、边坡护脚及压顶、边坡截排水等设计建议。  相似文献   

煤矿塌陷区复垦土壤环境质量评价   总被引：1，自引：0，他引：1  

马力阳  朱江  周俊  马来  李涛  杨洪波 《安徽地质》2014,(1):70-74

通过对煤矿塌陷区复垦土壤采样测试,研究土壤中重金属铜、锌、镉、汞、砷、铅、铬的含量对土壤环境的影响。研究结果表明:按单因子污染指数法和内梅罗综合污染指数法,结合国家土壤环境质量标准对复垦土壤的质量进行评价:研究区内土壤环境质量良好,基本上可以达到国家土壤环境质量二级标准,安全清洁级别;参照《无公害食品蔬菜产地环境条件标准》、《绿色食品产地环境质量标准》和《有机农业生产基地环境质量标准》,对复垦土壤的农用环境进行评价:研究区内土壤全部达到绿色食品产地环境质量标准,如果选择合理的修复方法,对部分有轻微污染的土壤进行,则可以达到有机农业生产基地环境质量标准;以潜在生态危害指数RI分析,复垦区内土壤重金属潜在生态危害指数相对较低,复垦区农业生产具有良好的发展前景。  相似文献   

降雨对松散堆积体滑坡稳定性影响探讨——以贵州省沿河土家族自治县为例     

周文江  舒多友 《四川地质学报》2014,34(3):424-428

降雨是引发滑坡灾害的主要原因之一。通过对沿河土家族自治县具代表性的四个松散堆积体滑坡的分析,认为最大降雨量与滑坡的稳定性系数、滑面倾角均成反比,而滑带土内摩擦角增加时,滑坡启动需要的降雨强度就越大,成正比。其认识与目前该类滑坡的监测数据变化特征总体相吻合。  相似文献