短期乔木林灌木林和草地演替的土壤剖面13C分布特征

以短期的植被更替如何影响土壤剖面的13C富集以及这些富集现象揭示的土壤碳循环机理为目的,采集云南省曲靖地区发生植被演替的山地土壤剖面5组,分别测定了稳定碳同位素比值(δ13C)、总有机碳含量(TOC)和碳密度,并比较了它们之间的差异。研究发现:短期植被改变(约10年)对土壤剖面中0~30 cm层的δ13C值具有显著影响,其中对0~10 cm层土壤影响最大。灌木更替为森林和草地后土壤有机质的δ13C变化分别达2.28‰和5.08‰。30~50 cm层土壤δ13C值对植被改变不敏感,该层可以作为土壤剖面的基准剖面层。大气δ13C值变化不是森林土壤0~50 cm剖面层中13C随深度减小而富集的主要原因。10年间,植被从灌木演替为人工种植的麻栎乔木或从灌木植被退化为草本植被,0~30 cm层土壤剖面的有机碳密度改变量分别为2.30 kg/m2和-1.00 kg/m2。而植被从灌木到人工种植麻栎的碳密度改变率为0.230 kg/m2/a,这对改变山地土壤的碳密度、短期增加碳储量具有重要意义。δ13C在C3植被的短期演替过程中具有很好的辨识力,可以作为土壤碳库更替和碳循环的研究工具。     

新疆艾比湖湿地自然保护区不同土壤类型无机碳分布特征

土壤无机碳（SIC）是干旱区土壤碳库的重要组成部分,分析其特征和储量是开展干旱区荒漠生态系统碳循环研究的必要基础。基于新疆艾比湖湿地自然保护区土壤剖面的实测数据,分析了不同土壤类型SIC分布特征及其差异性,估算了研究区SIC储量,并探讨SIC含量与分布、储量特点以及与土壤有机碳（SOC）和理化因子间关系。结果表明：各类型平均SIC含量为53.06～79.90 g·kg–1;类型间SIC含量有显著差异（p<0.05）,50 cm以上各层SIC含量顺序为灰棕漠土>盐碱土>水成土>荒漠风沙土,50 cm以下则盐碱土和水成土逐渐占优势。SIC含量的垂直分布总体表现为低-高-低的特征（10 cm单位土壤深度）,除灰棕漠土外,SIC含量在剖面上的变化较均匀。研究区无机碳密度平均为9.37 kg·m-2,SIC库储量为234.50 Tg。SIC含量与SOC及含水量呈显著的正相关,并随土壤深度增加有增加趋势;与土壤容重和表层pH值负相关,相关性较弱。     

森林转换对不同土层土壤碳氮含量及储量的影响

森林转换是影响森林碳氮储量的重要因素。研究森林转换对土壤碳氮的影响,对明确生态系统碳氮循环动态具有重要意义。对由中亚热带常绿阔叶天然林转换而成的阔叶天然次生林(BL)与杉木人工林(CF)不同土层的有机碳(SOC)、氮(TN)含量以及储量进行研究,探讨森林转换对地下土壤碳氮储量的影响及其影响因素。结果表明:(1)相同土层,阔叶天然次生林的SOC含量、TN含量高于杉木人工林,分别在0～40 cm各土层与0～20 cm各土层之间均具有显著性,相同森林类型下SOC含量与TN含量垂直拟合关系均以幂函数拟合效果最好,R~2均达到0.9以上,可以为当地碳氮含量估算提供依据,土壤碳氮比(C/N)均随土层深度增加而下降。(2)森林转换后0～100 cm碳氮储量(SCM、SNM)阔叶天然次生林高于杉木人工林。土壤碳氮在2种林分的差异主要集中在0～10 cm,且阔叶天然次生林显著高于杉木人工林。(3)相关分析显示土壤SOC、 TN含量与土壤容重呈显著负相关,与C/N之间呈极显著正相关(P0.01)。研究表明:森林土壤碳氮储量主要集中在0～10 cm土层,天然林转换为杉木人工林后,土壤碳氮含量降低,不利于森林碳氮储量的积累,因此要加大对天然林的保护。     

荒漠土壤微生物碳垂直分布规律对有机碳库的表征作用

以古尔班通古特沙漠南缘原始盐漠为研究对象,测定不同深度的土壤有机碳和土壤微生物碳含量,以分析它们之间的响应关系。结果表明:(1)在土壤垂直剖面上,土壤微生物碳（SMC）含量与有机碳（SOC）含量呈现极显著正线性相关（R2=0.63,p=0.0003）。（2）SMC出现了2个明显的改变界面（20 cm,80 cm）,0~20、20~80、80~500 cm值分别为:2.24~3.06、0.19~0.72、0.0017~0.0097 mg·kg-1;0~20 cm和20~80 cm的SMC差异极显著（p<0.0001）,20~80 cm和80~500 cm的SMC差异显著（p<0.05）。（3）对应于SMC的土壤层划分,SOC在0~20 cm、20~80 cm和80~500 cm同样具有一定的分层性。（4）我们把具有不同微生物活性的有机碳层分别定义为活性、惰性、稳定性有机碳库,土壤垂直剖面上微生物碳的分布很好地表征了土壤中活性、惰性、稳定性有机碳库的分布;通过对这3种碳库所在土层进行合理划分,可以定量分析土壤中3种有机碳库的储量。     

景宁望东垟高山湿地自然保护区沼泽土壤有机碳含量分布特征

为了研究山地沼泽土壤有机碳的分布特征,在浙江省南部景宁望东垟高山湿地自然保护区内的森林沼泽、草本沼泽和针阔混交林地中,设置采样地,于2018年9月6～8日,分别采集0～10 cm、10～30 cm、30～60 cm和60～100 cm深度的土壤样品,测定土壤有机碳含量及其活性组分含量,并分析其与其它土壤理化指标的关系。研究结果表明,随着土壤深度的增加,森林沼泽、草本沼泽和针阔混交林地土壤有机碳含量总体上逐渐减小,10～30 cm深度土壤轻组有机碳和颗粒有机碳含量显著低于0～10 cm深度土壤,各深度土壤可溶性有机碳含量差异不大;在0～10 cm、10～30 cm和30～60 cm深度土层,森林沼泽土壤中的可溶性有机碳含量占有机碳含量的比例显著高于草本沼泽,草本沼泽土壤中的颗粒有机碳含量占有机碳含量的比例显著高于森林沼泽和针阔混交林地,草本沼泽土壤有机碳库较稳定;森林沼泽和针阔混交林地土壤有机碳含量与土壤中的全氮和全磷含量显著相关,森林沼泽、草本沼泽和针阔混交林地土壤中的有机碳各活性组分含量与土壤有机碳含量显著相关。     

龙滩水库溶解无机碳来源及变化特征

河流在碳的运输过程中扮演着重要角色。为探究河流筑坝拦截后龙滩水库溶解无机碳(DIC)的来源和变化特征,于2016年7月和2017年1月采集水样,然后分析了河水DIC及其碳稳定同位素(δ13C)值。研究结果表明:(1)δ13CDIC值具有显著的时空差异,表明两个季节影响DIC的主要因素和DIC的来源并不相同。雨季,DIC及其δ13C主要分布在2.04~4.12 mmol·L^-1和-5.52‰^-2.87‰的范围内;旱季,水体DIC为3.33~4.61 mmol·L^-1,而δ13CDIC显著低于雨季为-15.90‰^-9.12‰。雨季,稀释效应显著降低了DIC浓度,由于水体热分层使得DIC在水柱剖面上差异显著,而旱季由于混合作用的影响,在剖面上差异较低。(2)在雨季,河流δ13CDIC较旱季明显偏正,碳酸盐岩的强烈风化输入大量HCO3-是DIC的主要来源。在旱季,DIC和δ13CDIC成反比关系,δ13CDIC在旱季变得更低,其大部分的DIC来自于土壤CO2输入和原位有机呼吸作用。旱季水体热分层消失,混合作用使得底部具有较低δ13C值的含碳水体上涌,并与表水层混合导致其δ13CDIC值低于雨季。这种季节性模式与自然河流不同,而是与湖泊的季节变化特征更为类似,说明河流拦截蓄水后逐渐湖沼化,并显著影响了DIC的循环。     

疏勒河源冻土区高寒草甸土壤碳氮含量特征

土壤碳氮是高寒植被响应多年冻土区生态环境变化的重要营养和能源物质,但对其调查仍以生长季的单次采样为主,缺乏对其他季节的研究,这对于准确把握多年冻土区土壤碳氮含量及储量评估存在明显局限性。为此,本研究以青藏高原东北缘祁连山西段疏勒河源多年冻土区高寒草甸为对象,对0—50 cm土层土壤有机碳（Soil Organic Carbon, SOC）、全氮（Total Nitrogen, TN）含量及其比值（C/N）的剖面分布和季节变化及其影响因素进行分析。结果表明：（1）SOC、TN剖面分布规律一致,0—10 cm土层均显著高于10—50 cm各层（P<0.05）,0—50 cm深度仅秋季逐渐下降,而春夏冬季0—30 cm递减。（2）SOC、TN含量存在季节变化,SOC表现为夏季>冬季>春季>秋季,TN表现为春秋冬季含量一致,夏季略低。（3）C/N季节变化显著,夏季显著最高,秋季显著最低（P<0.05）。（4）土壤含水量和生物量是影响SOC、TN及C/N剖面分布和季节变化的关键因素。（5）夏季土壤碳氮密度均高于全年平均。可见,仅单一节点（生长季为主）调查以表征全年土壤碳氮储量存在高估趋势。     

青藏高原腹地植物碳同位素组成对环境条件的响应

现代植物碳同位素组成是特定环境影响的结果,通过对植物碳同位素组成的研究可以揭示植物生长期环境信息。针对青藏高原腹地高寒草甸~高寒草原过渡区植被碳同位素组成进行研究;该区高山嵩草样δ13C值在-25.63‰~-27.95‰间,平均值-26.63‰;高寒草原区混合样δ13C值于-26.29‰~-27.73‰间,平均值-27.04‰。高山嵩草样δ13C值总体呈现由南东往北西方向正偏趋势,研究区北部高寒草原区混合植物样也呈现出由南向北富重碳同位素趋势。这些变化规律被认为是主要受降水环境影响的结果,而区域内降水条件的展布规律则是受高原夏季风运移方式的控制。对植物δ13C值与地理位置的回归分析表明,该区植被碳同位素组成与地理位置相关,高山嵩草样(r=0.44603,n=29,p<0.05)和混合样(r=0.8112,n=5,p<0.1)均表现出对区域降水环境条件的良好响应。据此,以该区植物δ13C值为背景,进行合理推算,拟定了研究区内干旱区和湿润区界限的位置。     

祁连山青海云杉(Picea crassifolia)林浅层土壤碳、氮含量特征及其相互关系

为阐明祁连山青海云杉(Picea crassifolia)林分布带对其土壤碳、氮含量的影响,以分布在祁连山东段和西段的典型青海云杉林为研究对象,通过野外取样和室内分析,论述了青海云杉林浅层土壤碳、氮含量特征及其相互关系。结果表明:(1)祁连山东、西段土壤剖面有机碳含量均随土壤深度的增加而减小,但不同土层差异显著性不同,0~40cm含量分别为73.57±17.17g·kg-1和45.85±11.93g·kg-1;东、西段土壤剖面有机碳储量没有明显的变化规律,0~40cm有机碳储量分别为205.51±39.44t·hm-2和134.93±25.80t·hm-2。(2)祁连山东、西段土壤全氮含量随土层深度变化和不同土层差异显著性变化规律同土壤有机碳含量,0~40cm全氮含量分别为4.56±0.88g·kg-1和2.81±0.66g·kg-1;东、西段土壤全氮储量亦同土壤有机碳储量变化规律,0~40cm储量分别为12.77±2.08t·hm-2和8.38±1.56t·hm-2。(3)祁连山东、西段土壤剖面不同土层C/N比差异显著性变化规律相同,其C/N值分别为15.92±1.24和16.10±2.07;C/N比值大小主要取决于有机碳含量;线性分析表明,土壤有机碳与全氮含之间呈极显著的正相关关系,可用乘幂曲线模型Y=aXb较好地描述(p0.01)。上述研究结果可为祁连山水源涵养林建群种青海云杉林的经营和管理提供理论依据和数据支撑。     

准噶尔盆地荒漠植物碳同位素组成研究

通过对准噶尔盆地古尔班通古特沙漠南缘17个科、41个属的53种荒漠植物的稳定碳同位素分析,结果显示准噶尔盆地荒漠植物的叶片稳定碳同位素值在-7.77‰~-30.10‰之间变化,其稳定碳同位素比值分布范围较广,C3和C4植物资源丰富。其中,C3植物有34种,δ13C值分布区间为-23.27‰~-30.10‰,平均值为-26.77‰;C4植物有19种,δ13C值的变化范围为-7.77‰～-14.90‰,平均值为-13.04‰。研究区内木本植物和草本植物的δ13C平均值分别为-16.74‰和-19.81‰,说明木本植物的水分利用效率明显高于草本植物,这种现象可能是全球荒漠生态系统的一种共性。但是一年生草本植物的δ13C平均值（-19.54‰）却高于多年生草本植物的δ13C平均值（-20.07‰）,由于植物叶片δ13C可以用来间接指示植物的长期水分利用效率,即δ13C值越大,植物的水分利用效率越高;也就是说在该地区,相对于多年生草本植物而言,一年生草本植物对环境的适应能力较强。     

土壤碳循环研究进展及干旱区土壤碳循环研究展望

土壤碳库动态及其驱动机制是陆地生态系统碳循环与全球变化研究的热点问题之一。随着各国对《京都议定书》的重视,农业土壤碳库变化及其源汇效应研究不断加强,但以往研究土壤碳循环主要是针对有机碳,较少考虑无机碳的作用和地位,干旱区土壤无机碳储量巨大,其在区域碳循环过程中的贡献日益显著,这使得干旱区土壤碳循环研究必须同时考虑土壤有机碳和无机碳的行为。国内外关于农业土壤有机碳动态的研究主要围绕农业土壤有机碳储量、固碳潜力等问题展开,研究区多为湿润、半湿润地区;国际上对农业土壤无机碳动态的研究主要集中在干旱区土地管理措施对土壤发生性碳酸盐碳的形成与转化方面,研究方法以稳定同位素技术为主,但目前关于中国干旱区农业土壤无机碳动态的研究还较为薄弱。因此,应加强干旱区绿洲土壤碳循环研究,深入分析干旱区绿洲土壤碳的源/汇效应;探讨土壤无机碳动态变化的机理。     

Modeling watershed-scale sequestration of soil organic carbon for carbon credit programs

Impending risks associated with climate change have forced the global community to devise tradable pollution permit or “cap and trade” approaches to control the release of greenhouse gases. In the U.S, soils have the potential to offset about 10 percent of annual CO₂ emissions; however, if carbon credits are to be included in greenhouse gas control programs, soil organic carbon (SOC) sequestration rates associated with agricultural land uses must be computed at a watershed scale. The Soil Water Assessment Tool (SWAT) water quality model, the Water Erosion Prediction Project (WEPP) erosion model, and the CENTURY 4.0 a soil carbon model were used to simulate carbon sequestration rates for 160 crop-tillage rotations in 272 sub-basins of the Big Creek watershed (12,300 hectares). Under annual crops, only no-till in a corn-soybean rotation, on low to moderate slopes results in net gains in SOC. Substantial annual rates of SOC sequestration occur only under perennial crops such as Conservation Reserve Program (CRP; 0.14 t/ha without erosion; 0.08 with erosion), pasture (0.67 t/ha without erosion; 0.58 with erosion), hay (0.88 t/ha without erosion; 0.52 with erosion), and forest (2.66 t/ha without erosion; 2.49 with erosion). Erosion thus has a large effect on the spatial distribution of field-measured SOC by moving it down slope and increasing its spatial variability. Because of this, carbon credit programs should be based on field practices, thus targeting the locations where the sequestration of atmospheric carbon actually occurs and minimizing monitoring costs. Developing model-based estimates of SOC sequestration rates of field practices at many locations would thus greatly serve the needs of carbon crediting programs.     

Estimation of soil organic carbon reservoir in China

The paper respectively adopted physio-chemical properties of every soil stratum from 2473 soil profiles of the second national soil survey. The corresponding carbon content of soils is estimated by utilizing conversion coefficient 0.58. In the second soil survey, the total amount of soil organic carbon is about 924.18×108t and carbon density is about 10.53 kgC/m2 in China according to the area of 877.63×106 hm2 surveyed throughout the country. The spatial distribution characteristics of soil organic carbon in China is that the carbon storage increases when latitude increases in eastern China and the carbon storage decreases when longitude reduces in northern China. A transitional zone with great variation in carbon storage exists. Moreover, there is an increasing tendency of carbon density with decrease of latitude in western China. Soil circle is of great significance to global change, but with substantial difference in soil spatial distribution throughout the country. Because the structure of soil is inhomogeneous, it could bring some mistakes in estimating soil carbon reservoirs. It is necessary to farther resolve soil respiration and organic matter conversion and other questions by developing uniform and normal methods of measurement and sampling.     

Estimation of soil organic carbon reservoir in China

1 IntroductionResearch on global change has aroused many scientists' attention to the balance, storage and spatial distribution of carbon in the terrestrial ecosystem. The carbon stored in soil is 2.5-3 times as much as that stored in plants[1,2], so the distribution and conversion of carbon in humus has become one of the global research foci on organic carbon at present[3]. Organic carbon and nitrogen contents in soils are not only important components of soils but also the most important eco…     

中国陆地土壤有机碳库的估算

土壤是陆地生态系统的核心之一,土壤有机碳库是陆地碳库的主要组成部分,在陆地碳循环研究中有着重要的作用,因而了解土壤碳循环是研究中国陆地生态系统碳循环的基础,确定土壤有机碳的储量、空间分布、对土壤碳循环的研究具有重要意义。根据中国和线次土壤普查得到的土壤各类型分布面积,采样数据、土壤有机质含量,运用ＧＩＳ技术,来估算土壤碳库。经过计算,中国陆地生态系统土壤有机碳总量为１００１．８×１０＾８ｔ,平均碳     

Content and densities of soil organic carbon in urban soil in different function districts of Kaifeng

Urban soil, forming along with the development of city, has unique properties of soil organic carbon. On the basis of field investigation and laboratory analysis, soil organic carbon (SOC) of Kaifeng city was studied, and the results showed that the characteristics of SOC were different not only among function districts in urban area, but also between urban area and suburbs. The order of SOC in topsoil was industrial district > recreational district > traffic district > cultural/educational district > residential/administrative district. The density of soil organic carbon (SOCD) in both topsoil and profile followed the orders of recreational district > industrial district > traffic district>cultural/educational district > residential/administrative district, and cultural/educational district s>traffic district>industrial district>recreational district > administrative/residential district, respectively. SOCD in both topsoil and profile decreased along the transection line from urban area to suburbs and urban area had 2.53-fold more SOCD in topsoil and 1.56-fold more SOCD in profile than suburbs, respectively. SOC decreased with the depth and was mainly distributed within the scope of 0–30 cm. The variances of SOC in urban area were more complicated than that in suburbs.     

Content and densities of soil organic carbon in urban soil in different function districts of Kaifeng

Urban soil, forming along with the development of city, has unique properties of soil organic carbon. On the basis of field investigation and laboratory analysis, soil organic carbon (SOC) of Kaifeng city was studied, and the results showed that the characteristics of SOC were different not only among function districts in urban area, but also between urban area and suburbs. The order of SOC in topsoil was industrial district > recreational district > traffic district > cultural/educational district > residential/administrative district. The density of soil organic carbon (SOCD) in both topsoil and profile followed the orders of recreational district > industrial district > traffic district>cultural/educational district > residential/adminis- trative district, and cultural/educational district > traffic district>industrial district>recreational district > administrative/residential district, respectively. SOCD in both topsoil and profile decreased along the transection line from urban area to suburbs and urban area had 2.53-fold more SOCD in topsoil and 1.56-fold more SOCD in profile than suburbs, respectively. SOC decreased with the depth and was mainly distributed within the scope of 0–30 cm. The variances of SOC in urban area were more complicated than that in suburbs.     

开封市不同功能区城市土壤有机碳含量与密度分析(英文)

Urban soil, forming along with the development of city, has unique properties of soil organic carbon. On the basis of field investigation and laboratory analysis, soil organic carbon (SOC) of Kaifeng city was studied, and the results showed that the characteristics of SOC were different not only among function districts in urban area, but also between urban area and suburbs. The order of SOC in topsoil was industrial district > recreational district > traffic district > cultural/educational district > residential/administrative district. The density of soil organic carbon (SOCD) in both topsoil and profile followed the orders of recreational district >industrial district > traffic district>cultural/educational district > residential/adminis- trative district, and cultural/educational district > traffic district>industrial district>recreational district > administrative/residential district, respectively. SOCD in both topsoil and profile decreased along the transection line from urban area to suburbs and urban area had 2.53-fold more SOCD in topsoil and 1.56-fold more SOCD in profile than suburbs, respectively. SOC decreased with the depth and was mainly distributed within the scope of 0-30 cm. The variances of SOC in urban area were more complicated than that in suburbs.     

干旱区盐碱土剖面无机碳组分分布特征

通过分离土壤动态性无机碳,结合14C同位素技术,有效量化了盐碱土剖面无机碳组分的存储数量和年龄特征。结果表明：整个土壤剖面,盐土难溶性无机碳含量和可溶性无机碳含量明显高于碱土。无论是土壤难溶性无机碳储量还是可溶性无机碳储量,盐土和碱土中有近80%碳是存储在1 m以下,50%存储于3 m以下。相同土层,土壤可溶性无机碳储量约占土壤难溶性无机碳储量的30%。无论是盐土还是碱土,无机碳的年龄超过万年,而土壤可溶性无机碳的年龄明显低于土壤无机碳的年龄。研究结果证实尽管土壤可溶性无机碳储量较低,但其周转时间短,速率高,因此在参与现代碳循环的程度上明显要高于土壤无机碳。     

青海省土壤有机碳估算及其不确定性分析

土壤有机碳对区域碳平衡起着关键性的作用,量化其空间格局及动态变化是准确评估生态系统碳汇潜力的基础。然而,不同土壤有机碳估算方法和不同样本得出的结果存在非常大的差异和不确定性,尤其是地形复杂、对气候变化敏感的青藏高原地区。为定量评估不同方法估算的土壤有机碳密度空间分布格局在青藏高原地区的差异,论文以青海省为研究区,收集整理了青海省806个土壤有机碳密度采样点数据,基于气候、植被、地形和土壤等多种解释变量,采用逐步回归、反距离权重插值、普通克里格插值和随机森林模型4种不同的方法,对青海省表层(0~30 cm)土壤有机碳密度空间分布及其影响因素进行了探究。结果表明,归一化植被指数、光合有效辐射、总氮、年均温、海拔、年降水量和净初级生产力是土壤有机碳密度估算的重要变量;尽管4种方法所估算的青海省土壤有机碳密度的均值较为接近,处于5.14~5.62 kg C·m^-2之间,但其变化范围存在较大差异,分别为0.17~23.25、0.34~46.61、0.56~35.08和0.62~24.85 kg C·m^-2;4种方法模拟结果的均方根误差分别为3.93、3.37、3.48和3.19 kg C·m^-2,平均标准差分别为0.12、0.51、0.61和0.27 kg C·m^-2,其中随机森林模型的结果较为稳定且精度较高,也更能准确反映青海省土壤有机碳的空间分布格局。比较发现,现有的土壤有机碳产品(SoilGrids250m 2.0和HWSD v1.2)在反映青海省土壤有机碳的分布方面还存在较大差异,相对而言,SoilGrids250m 2.0产品的土壤有机碳和随机森林模拟结果比较接近。