天山北坡绿洲土壤有机碳和养分时空变异特征

本文以天山北坡三工河流域绿洲作为研究区,利用1982、1999和2003年土壤养分数据,应用地统计学方法,分析绿洲土壤有机碳和养分的时空变异特征。结果显示:研究区1982、1999和2003年土壤有机碳和养分具有显著的差异性。空间结构上,土壤有机碳和养分具有中等或较弱的空间自相关;受土壤类型、种植作物种类等的影响,研究区土壤有机碳具有较强的各向异性,但碱解氮、速效磷和速效钾各向异性较弱。Kriging和IDW插值分析表明,土壤有机碳和养分总体呈增加的趋势,绿洲土壤表现为“碳汇”,尤其在种植6年以上的多年生作物分布区,土壤“碳汇”趋势更加明显,说明以绿洲农业为主的人类活动基本合理,土壤质量正逐步改善。     

川中丘陵区紫色土表层土壤有机碳分布及影响因素

以2004～2006年间野外采样数据，采用土壤类型法对川中丘陵区（内江、资阳和遂宁三市）紫色土表层土壤有机碳密度及储量进行估算，分析了土壤有机碳密度的分布差异。据统计研究区紫色土面积为9070．19km^2，研究结果：表层土壤有机碳密度介于3．32kgC／m^2～1．71kgC／m^2间，具有高度的变异性，表层土壤有机碳储量为1．84Tg。并对影响紫色土有机碳分布的母质、地形和土地利用方式等因素进行了分析：不同成土母质上发育的表层土壤有机碳密度有差异，但均与母岩及其风化物有较强的相关性；主要土属从丘顶到丘脚土壤有机碳密度均逐渐增高；不同土地利用方式下土壤有机碳密度不同，但基本遵循疏林地〉荒草地〉坡耕地的规律。     

阿里荒漠区土壤有机碳分布特征及其与土壤物理性质的关系

为完善阿里荒漠区土壤本底数据,提高对高寒荒漠土壤碳汇水平的认识,以青藏高原阿里荒漠区0～100 cm土层为研究对象,通过对分布在全区34个样点的野外调查、样品收集与室内试验,探讨了土壤有机碳含量(soil organic carbon, SOC)与土壤有机碳密度(soil organic carbon density, SOCD)的分布特征及其与植被类型和土壤物理性质的关系。结果表明：(1)0～100 cm深度的SOC和SOCD均值分别为3.74 g·kg^-1和4.91 kg·m^-2,在全国范围内处于较低水平;在垂直方向上,SOC与SOCD从表层逐渐向深层递减,具有明显的表聚现象。(2)全区的SOC与SOCD表现为强变异性,而且因植被类型不同呈显著差异(P≤0.05),水平方向上呈现为由东北向西南从荒漠草原、草原化灌木荒漠、半灌木-矮半灌木荒漠再到无植被区域的递减趋势。(3)区内土壤的容重和砂粒含量随深度增加而逐渐增加,含水量、黏粒含量和粉粒含量逐渐减少,在部分植被盖度低的区域土壤含水量和黏粒含量随土层深度呈现出低—高—低趋势。土壤含水量、粉...     

我国东部土壤有机碳的密度及转化的控制因素

根据第二次土壤普查资料，计算了我国东部土壤的有机密度和储量，并通过田间和室内试验的结果，分析了影响农田土壤中有机碳转化的因素。结果表明，我国东北地区土壤有机碳密度变幅为2．5－73．3kg C/m^2，平均值为10．5kg C/m^2，而在东南热带亚热带地区，剖面土壤有机碳密度变幅为3．9－16．7kg C/m^2，平均值为9．52％kg C/m^2。随着木质素含量和土壤粘粒含量的增加，植物物质的分速率下降，而土壤温度，pH和游离碳酸钙含量的增加促进了 植物物质的分解；淹水的水田中植物物质的分解速率通常低于旱地；土壤性质和有机物组成对植物物质分解的影响可以掩盖气候条件的影响，而土壤游离碳酸钙可以掩盖土壤质地的影响。     

土壤侵蚀对农田中土壤有机碳的影响

碳主要在通气状态下释放出CO₂以温室效应的形式影响全球变化。当前,农田土壤固碳过程是土壤碳循环研究中的一个前沿领域,其中农田土壤再分布过程能否导致土壤固碳已引起科学上、政治上以及社会上广泛的兴趣。本文从不同的尺度阐述土壤再分布过程对土壤有机碳的影响。分别阐述土壤侵蚀和再沉积过程在全球碳循环,陆地碳库研究中的作用,土壤侵蚀与农田景观土壤有机碳动态、活性组份以及碳通量之间的关系,土壤再分布过程引起的土壤固碳机理。在此基础上指出今后迫切需要解决的问题。     

美国俄亥俄州土壤有机碳密度空间分布(英文)

Historical database of National Soil Survey Center containing 1424 geo-referenced soil profiles was used in this study for estimating the organic carbon(SOC) for the soils of Ohio,USA.Specific objective of the study was to estimate the spatial distribution of SOC density(C stock per unit area) to 1.0-m depth for soils of Ohio using geographically weighted regression(GWR),and compare the results with that obtained from multiple linear regression(MLR).About 80% of the analytical data were used for calibration and 20% for validation.A total of 20 variables including terrain attributes,climate data,bedrock geology,and land use data were used for mapping the SOC density.Results showed that the GWR provided better estimations with the lowest(3.81 kg m 2) root mean square error(RMSE) than MLR approach.Total estimated SOC pool for soils in Ohio ranged from 727 to 742 Tg.This study demonstrates that,the local spatial statistical technique,the GWR can perform better in capturing the spatial distribution of SOC across the study region as compared to other global spatial statistical techniques such as MLR.Thus,GWR enhances the accuracy for mapping SOC density.     

土地覆盖类型对科尔沁沙地南缘土壤有机碳储量的影响

研究了科尔沁沙地南缘土地覆盖由流动沙地向人工林地、农田及固定沙地等转变后,0~60 cm土层有机碳储量的变化。结果表明：农田土壤有机碳含量增加最明显,为流动沙地的3.97倍且相同层间差异均显著;樟子松（Pinus sylvestris var. mongolica）林地、新疆杨（Populus alba var. pyramidalis）林地、小叶锦鸡儿（Caragana microphylla）群落土壤有机碳含量较流动沙地分别增加79.78%、138.20%、73.07%,差异主要在0~20 cm土层;围封草地和中度放牧草地分别增加116.85%和133.71%,差异主要在0~40 cm土层;固定沙地比流动沙地增加49.44%,差异主要在0~20 cm土层。土地覆盖类型转变后,由于受到土壤容重的影响,土壤有机碳密度在0~20 cm土层变化较明显。8种土地覆盖类型可分为4组：CL1（农田）、CL2（新疆杨林地、围封草地、中度放牧草地）、CL3（樟子松林地、小叶锦鸡儿群落、固定沙地）和CL4（流动沙地）。另外,土壤有机碳含量和密度在土壤剖面上的分布也随着土地覆盖类型的变化而不同。     

海南岛土壤有机碳空间分布特征及储量

利用2005年海南岛生态地球化学调查获得的8713件表层土壤和2197件深层土壤样品,计算分析海南岛土壤有机碳的空间分布特征,结果显示:0～20 cm、0～100 cm、0～180 cm 3个深度的土壤有机碳密度分别为2.86、9.48、13.72 kg/m2,与国内其他典型地区相比,几乎处于最低水平.区域土壤有机碳密度图显示,海南岛土壤有机碳的分布与地貌类型关系密切,高值区分布在山地、丘陵、火山岩台地等地区,其次是平原区,最低为滨海地区.统计显示,土地利用类型、土类不同,土壤有机碳密度差异明显,不同地类土壤有机碳密度:园地＞林地＞其他土地＞耕地,土壤有机碳主要贮存在林地和耕地中;不同土类土壤有机碳密度:黄壤＞赤红壤＞砖红壤＞水稻土＞燥红土,土壤有机碳主要贮存在砖红壤、赤红壤和水稻土中;0～180 cm土壤有机碳库储量为478.13 Mt.     

小陇山国家级自然保护区油松种群更新及生存

以种群生命表及生存分析理论为基础,以林木径级结构代表年龄结构,采用分段匀滑技术,编制小陇山自然保护区油松种群特定时间生命表,绘制死亡率曲线、消失率曲线、存活曲线、生存函数曲线,分析种群数量动态特征,并对其年龄跟胸径进行线性回归。结果表明:1.油松种群年龄结构表现为稳定型。2.油松种群死亡率和消失率曲线变化趋势基本一致,存活曲线趋于Deevey-Ⅱ型。4个生存函数曲线表明,油松种群具有前期稳定、中后期锐减和末期衰退的特点。3.油松年龄与其胸径线性相关。     

Three-dimensional modelling of soil organic carbon density and carbon sequestration potential estimation in a dryland farming region of China

Soil organic carbon density(SOCD) and soil organic carbon sequestration potential(SOCP) play an important role in carbon cycle and mitigation of greenhouse gas emissions. However, the majority of studies focused on a two-dimensional scale, especially lacking of field measured data. We employed the interpolation method with gradient plane nodal function(GPNF) and Shepard(SPD) across a range of parameters to simulate SOCD with a 40 cm soil layer depth in a dryland farming region(DFR) of China. The SOCP was estimated using a carbon saturation model. Results demonstrated the GPNF method was proved to be more effective in simulating the spatial distribution of SOCD at the vertical magnification multiple and search point values of 3.0×10~6 and 25, respectively. The soil organic carbon storage(SOCS) of 40 cm and 20 cm soil layers were estimated as 22.28×10~(11) kg and 13.12×10~(11) kg simulated by GPNF method in DFR. The SOCP was estimated as 0.95×10~(11) kg considered as a carbon sink at the 20–40 cm soil layer. Furthermore, the SOCP was estimated as –2.49×10~(11) kg considered as a carbon source at the 0–20 cm soil layer. This research has important values for the scientific use of soil resources and the mitigation of greenhouse gas emissions.     

Effects of afforestation on soil carbon turnover in China’s subtropical region

Afforestation in China’s subtropics plays an important role in sequestering CO2 from the atmosphere and in storage of soil carbon (C). Compared with natural forests, plantation forests have lower soil organic carbon (SOC) content and great potential to store more C. To better evaluate the effects of afforestation on soil C turnover, we investigated SOC and its stable C isotope (δ13C) composition in three planted forests at Qianyanzhou Ecological Experimental Station in southern China. Litter and soil samples were collected and analyzed for total organic C, δ13C and total nitrogen. Similarly to the vertical distribution of SOC in natural forests, SOC concentrations decrease exponentially with depth. The land cover type (grassland) before plantation had a significant influence on the vertical distribution of SOC. The SOC δ13C composition of the upper soil layer of two plantation forests has been mainly affected by the grass biomass 13C composition. Soil profiles with a change in photosynthetic pathway had a more complex 13C isotope composition distribution. During the 20 years after plantation establishment, the soil organic matter sources influenced both the δ13C distribution with depth, and C replacement. The upper soil layer SOC turnover in masson pine (a mean 34% of replacement in the 10 cm after 20 years) was more than twice as fast as that of slash pine (16% of replacement) under subtropical conditions. The results demonstrate that masson pine and slash pine plantations cannot rapidly sequester SOC into long-term storage pools in subtropical China.     

黄土高原子午岭林区油松林种子雨强度及时空动态特征

通过布设种子收集器（接种框）,对黄土高原子午岭林区的油松密林、油松林缘和单株油松（孤立木）的种子雨强度、种子雨历时、种子散播的时空分布特征进行了分析研究。结果表明：（1）油松林内、林缘、孤立木输入地面的种子总量分别为85.5、191.5、178.0粒·m^-2,不同母树类型种子雨强度有明显差异;（2）油松种子降落从10月初开始,11月初结束,种子雨历时约32 d;种子雨在10 d左右达到峰值;（3）林内种子雨强度有较大的空间异质性,种子分布呈聚集分布格局（扩散系数C=33.618）;（4）种子雨过程中不同类型种子的消长趋势及所占比重不同,完整种子在种子雨初期占有优势,未成熟种子在种子雨后期急剧增加,而残缺种子在整个种子雨过程中占的比重变化不大,完整、未成熟和残缺种子累积总量与种子雨强度呈线性相关;（5）林缘和孤立木的种子雨集中在距母树1～3 m的冠幅范围内,这说明油松种子雨扩散以重力传播为主。     

中亚热带山区土地利用变化对土壤有机碳储量和质量的影响

Land use/cover change (LUCC) is widely recognized as one of the most important driving forces of global carbon cycles. The influence of converting native forest into plantations, secondary forest, orchard and arable land on stores and quality of soil organic carbon (SOC) was investigated in mid-subtropical mountainous area of southern China. The results showed that LUCC had led to great decreases in SOC stocks and quality. Considerable SOC and light-fraction organic carbon (LFOC) had been stored in the native forest (142.2 t hm⁻² and 14.8 t hm⁻² respectively). When the native forest was converted to plantations, secondary forest, orchard and arable land, the SOC stocks decreased by 25.6%, 28.7%, 38.0%, 31.8% and 51.2%, respectively. The LFOC stocks decreased by 52.2% to 57.2% when the native forest was converted to woodland plantations and secondary forest, and by 82.1% to 84.2% when converted to economic plantation, orchard and arable land. After the conversion, the ratios of LFOC to SOC (0–60 cm) decreased from 13.3% to about 3.0% to 10.7%. The SOC and LFOC stored at the upper 20 cm were more sensitive to LUCC when compared to the subsurface soil layer. Also, the decline in carbon storage induced by LUCC was greater than the global average level, it could be explained by the vulnerable natural environment and special human management practices. Thus, it is wise to enhance soil carbon sequestration, mitigate elevated atmospheric CO₂ and develop ecological services by protecting vulnerable environment, restoring vegetation coverage, and afforesting in mountainous area in mid-subtropics. Foundation: Supported by the Key Project of Ministry of Education of China, No.JA04166 Author: Yang Yusheng (1964–), Professor, specialized in carbon and nitrogen cycles of forest.     

The impact of land use/cover change on storage and quality of soil organic carbon in midsubtropical mountainous area of southern China

Land use/cover change (LUCC) is widely recognized as one of the most important driving forces of global carbon cycles. The influence of converting native forest into plantations, secondary forest, orchard and arable land on stores and quality of soil organic carbon (SOC) was investigated in mid-subtropical mountainous area of southern China. The results showed that LUCC had led to great decreases in SOC stocks and quality. Considerable SOC and light-fraction organic carbon (LFOC) had been stored in the native forest (142.2 t hm?2 and 14.8 t hm?2 respectively). When the native forest was converted to plantations, secondary forest, orchard and arable land, the SOC stocks decreased by 25.6%, 28.7%, 38.0%, 31.8% and 51.2%, respectively. The LFOC stocks decreased by 52.2% to 57.2% when the native forest was converted to woodland plantations and secondary forest, and by 82.1% to 84.2% when converted to economic plantation, orchard and arable land. After the conversion, the ratios of LFOC to SOC (0–60 cm) decreased from 13.3% to about 3.0% to 10.7%. The SOC and LFOC stored at the upper 20 cm were more sensitive to LUCC when compared to the subsurface soil layer. Also, the decline in carbon storage induced by LUCC was greater than the global average level, it could be explained by the vulnerable natural environment and special human management practices. Thus, it is wise to enhance soil carbon sequestration, mitigate elevated atmospheric co2 and develop ecological services by protecting vulnerable environment, restoring vegetation coverage, and afforesting in mountainous area in mid-subtropics.     

安徽省土壤有机碳空间差异及影响因素

区域土壤碳储量和碳固定潜力及影响因素分析是全球变化中碳循环研究的重要前沿问题。本文采用第二次土壤普查资料,研究了安徽省不同类型土壤的有机碳密度和碳库,分析了影响土壤有机碳分布的自然和人为因素。结果表明,安徽土壤有机碳库为0.71Pg,表层土壤有机碳库为0.28Pg;土壤平均有机碳密度达117.54 t/hm²,碳密度的空间分布为:皖南山区>皖西大别山区>沿长江平原>江淮丘陵区>淮北平原区;气候和植被控制着表层土壤有机碳的省域分布,降水与土壤有机碳含量呈正相关。地形和母质影响土壤亚类间有机碳的差异;土壤总氮与土壤有机碳呈极显著相关,平原区土壤粘粒含量与表层土壤有机碳固定有较大关系。     

开垦对内蒙古温带草地土壤不同有机碳组分的影响(英文)

Cultivation is one of the most important human activities affecting the grassland ecosystem besides grazing, but its impacts on soil total organic carbon (C), especially on the liable organic C fractions have not been fully understood yet. In this paper, the role of cropping in soil organic C pool of different fractions was investigated in a meadow steppe region in Inner Mongolia of China, and the relationships between different C fractions were also discussed. The results indicated that the concentrations of different C fractions at steppe and cultivated land all decreased progressively with soil depth. After the conversion from steppe to spring wheat field for 36 years, total organic carbon (TOC) concentration at the 0 to 100 cm soil depth has decreased by 12.3% to 28.2%, and TOC of the surface soil horizon, especially those of 0-30 cm decreased more significantly (p<0.01). The dissolved organic carbon (DOC) and microbial biomass carbon (MBC) at the depth of 0-40 cm were found to have decreased by 66.7% to 77.1% and 36.5% to 42.4%, respectively. In the S.baicalensis steppe, the ratios of soil DOC to TOC varied between 0.52% and 0.60%, and those in the spring wheat field were only in the range of 0.18%-0.20%. The microbial quotients (qMBs) in the spring wheat field, varying from 1.11% to 1.40%, were also lower than those in the S. baicalensis steppe, which were in the range of 1.50%-1.63%. The change of DOC was much more sensitive to cultivation disturbance. Soil TOC, DOC, and MBC were significantly positive correlated with each other in the S. baicalensis steppe, but in the spring wheat field, the correlativity between DOC and TOC and that between DOC and MBC did not reach the significance level of 0.05.     

中国东部土壤水溶性有机物荧光特征及地域分异

测定中国东部地区20种土类46个表土样品水溶性有机物的荧光光谱、分子量以及pH值，分析了水溶性有机物荧光光谱的一般特征、荧光光谱与其平均分子量的关系以及荧光强度的地域分异特性，与此同时比较分析了土壤富里酸的相关特征，结果表明研究区土壤水溶性有机物和富里酸具有相似的荧光光谱特征和地域分异特性，即在所研究的浓度范围内两者的荧光发射光值与有机物浓度成良好的线性正相关关系，而荧光强度与分子量分布无直接相关性，研究区土壤水溶性有机物和富里酸荧光强度均具有自北向南递降的趋势；土壤pH可能是影响水溶性有机物荧光特征及空间分异的主要因素。