川西亚高山针叶林土壤颗粒的分形特征

分形理论为土壤等复杂体系的定量化研究提供了一种有效工具。本文以12个川西亚高山针叶林土壤颗粒组成数据为基础,运用分形模型研究了亚高山针叶林土壤颗粒的分形维数。结果表明,12个川西亚高山针叶林表层土壤颗粒的分形维数D为2.5209~2.7978。通过逐步多元回归分析,土壤颗粒分形维数仅与<0.001 mm颗粒含量的相关系数达极显著。土壤颗粒分形维数与土壤有机质含量、全氮含量和pH相关性不显著,然而土壤有机质含量与全氮含量呈极显著正相关。本研究探讨了利用土壤颗粒粒径分布的分形维数来定量表征川西亚高山针叶林土壤的特征。     

黑土表层土壤颗粒的分形特征

基于第二次全国土壤普查结果,应用土壤颗粒的质量分布计算了36个典型剖面表层土壤颗粒的分形维数值.结果表明:土壤颗粒分形维数值D在2.5831～2.8230,其变异性极弱,且分形维数值随质地变细而增大;土壤机械组成中,砂粒(2～0.02mm)含量、粉粒(0.02～0.002mm)含量与分形维数值均呈显著负相关(P<0.05);粘粒(<0.002mm)含量与土壤分形维数值呈极显著正相关(P<0.01);分形维数值D与土壤中的有机质、全N、全P、全K含量及pH值相关性均不显著.土壤分布的分形维数可以作为反映黑土退化程度的一个综合性定量指标.     

英罗港红树林土壤粒径分布的分形特征

应用分形理论分析了英罗港红树林土壤粒径分布的分形特征。结果表明,红树林土壤的分形维数为2.6837-2.8834,不同质地土壤的分形维数呈现砂壤土＜轻壤土＜中壤土＜重壤土＜轻粘土的规律,外滩红树林土壤的分形维数低于中滩和内滩。土壤分形维数与其盐分和有机质含量呈显著正相关。群落类型、土壤质地、滩位、含盐量、有机质含量等是影响英罗港红树林土壤分形维数的主要因子。     

南亚热带不同林分土壤颗粒分形与水分物理特征

以广西国有高峰林场的6种不同林分(马尾松林Pinus massoniana、杉木林Cunninghamia lanceolata、尾巨桉林Eucalyptus urophylla×E. grandis、米老排林Mytilaria laosensis、红锥林Castanopsis hystrix和天然次生林)为对象,运用分形学和森林水文学的理论和方法,研究了不同林分类型土壤的颗粒组成以及水分物理特征。结果表明:研究区不同林分类型的土壤颗粒组成以黏粒为主,其次为粉粒和细砂粒,粗砂粒的含量相对较低,土壤颗粒分形维数从大到小依次表现为天然次生林、杉木林、米老排林、红锥林、马尾松林和尾巨桉林;不同林分类型土壤的水分物理特征存在差异,蓄水性能大小依次表现为天然次生林、米老排林、杉木林、红锥林、马尾松林和尾巨桉林,且土壤表层(0~10 cm)的蓄水能力要好于下层(20~50 cm);土壤颗粒分形维数主要受黏粒含量的影响,分形维数与黏粒含量呈极显著正相关,与总孔隙度、饱和蓄水量显著正相关,与土壤密度显著负相关,而与非毛管孔隙度、非毛管蓄水量和有机质含量相关性不显著。土壤颗粒分布的分形维数可作为反映南亚热带赤红壤地区人工林土壤水文物理性质的综合性指标。     

荒漠草原不同植被微斑块土壤粒径分布分形特征与养分的关系

采集宁夏中部干旱带荒漠草原4种植被(猪毛蒿、甘草、苦豆子、草木樨状黄芪)微斑块土壤剖面3个层次土壤,测定了各微斑块土壤颗粒粒级分布、有机质、pH值、土壤电导率(EC)、全氮、全磷和全钾等理化性质,探讨了不同植被微斑块土壤粒径分布的分形维数(D)特征及其与土壤理化性质的关系.结果表明:斑块化植被分布可影响土壤粒径分布,其影响作用以草木樨状黄芪微斑块最大(D=2.51),甘草微斑块最低(D=2.46);分形维数与黏粒、粉粒含量呈显著正相关,而与砂粒含量呈显著负相关;土壤粒径分布分形维数与pH和EC呈显著正相关,与有机质和全氮含量呈显著负相关,与全磷和全钾含量无显著相关关系.斑块化植被分布有潜在土地盐碱化和土地退化的趋势.     

轮牧方式对荒漠草原土壤团聚体及有机碳特征的影响

合理的草地轮牧方式对草原的科学管理具有重要意义.以宁夏荒漠草原为研究对象,对围封禁牧、连续放牧和二区、四区及六区轮牧下0~30 cm土层土壤团聚体分布特征、稳定性、有机碳含量及其贡献率进行了研究.结果表明: 除围封禁牧草地以机械稳定性大团聚体为主外,其他处理的土壤水稳性团聚体均以微团聚体为主;增加轮牧分区有利于表层土壤水稳性团聚体含量的保持及大团聚体含量增加.机械稳定性团聚体分形维数在连续放牧下最大,增加轮牧分区则呈现减小趋势,但水稳性团聚体分形维数无明显变化规律;团聚体平均重量直径(MWD)及几何平均直径(GMD)在禁牧草地最大,且随着轮牧分区的增加而增大;MWD和GMD与微团聚体含量呈显著负相关.水稳定性大团聚体有机碳含量以六区轮牧和围封禁牧较高,二区轮牧和连续放牧较低;试验区微团聚体有机碳对土壤有机碳含量贡献率较高,但0~20 cm土层中,轮牧分区越多则大团聚体有机碳贡献率越高.从土壤团聚体及其有机碳特征考虑,六区轮牧为研究区荒漠草原最适宜的轮牧方式.     

不同还田方式对砂质潮土理化性质及微生物的影响

为探索不同物料还田方式对中低产田砂质潮土的改良效果,在黄淮海平原麦玉轮作区典型砂质潮土上进行了连续6季的田间小区试验,设置全量秸秆翻耕还田(TS),秸秆等碳量的生物炭(TB)及半量秸秆半量生物炭配合翻耕还田(TSB),全量秸秆免耕覆盖还田(NTS)和半量秸秆半量生物炭配合免耕覆盖还田(NTSB),共5种还田方式。结果表明,与常规秸秆翻耕还田(TS)相比,生物炭翻耕还田(TB)显著降低土壤容重,增加玉米各个生育期土壤水分和p H值,有机质含量提升了16.4%,但TB处理的土壤大团聚体降低了21.2%和微生物数量降低了16.1%;翻耕秸秆配合生物炭还田(TSB)除了显著降低了大团聚体数量,对其余理化及微生物指标的影响均不显著;免耕模式下的秸秆还田(NTS)和秸秆生物炭配施(NTSB)分别在玉米生长的喇叭口期和收获期显著增加了土壤水分含量、耕层土壤的微生物数量和有效降低砂质潮土分形维数,对容重和有机质含量有一定的改善,其中NTSB有机质含量提升了14.9%和微生物数量增加了53.7%,对砂质潮土改良效果更好。总体来说,短期内用等碳量的生物炭替代秸秆翻耕还田更多的表现为物理的掺混效应,虽能有效提升土壤有机质含量,但不能有效改善砂质潮土的物理结构及生物性质,一半秸秆用生物炭替代还田对该类土壤的理化及微生物指标的改良效果也不显著,而免耕条件下秸秆配合生物碳还田效果最佳,可为砂质潮土的改良提供新的途径和理论依据。     

Specific Surface Area Effect on Adsorption of Chlorpyrifos and TCP by Soils and Modelling

The adsorption of chlorpyrifos and TCP (3,5,6, trichloro-2-pyridinol) was determined in four soils (Mollisol, Inceptisol, Entisol, Alfisol) having different specific surface areas (19–84 m² g^?1) but rather similar organic matter content (2.4–3.5%). Adsorption isotherms were derived from batch equilibration experiments at 25°C. After liquid-liquid extraction, the chlorpyrifos and TCP concentrations in the solution phase were determined by gas chromatography with an electron capture detector. Adsorption coefficients were calculated using the Freundlich adsorption equation. High K_F coefficients for chlorpyrifos (15.78) and TCP (6.54) were determined for the Entisol soil, while low K_F coefficients for chlorpyrifos (5.32) and TCP (3.93) were observed in the Alfisol soil. In all four soils, adsorption of chlorpyrifos was higher than that of TCP. A surface complexation model, the constant capacitance model, was well able to fit the adsorption isotherms of both chlorpyrifos and TCP on all four soils. The results showed that specific surface area affected adsorption of both chlorpyrifos and TCP. Among the soil properties, specific surface area could be a better indicator than organic matter content alone for adsorption of chlorpyrifos and TCP by soils that contained low organic matter.     

禹城市耕地土壤盐分与有机质的指示克里格分析

针对目前黄淮海平原盐渍土改良区存在的土壤盐碱、瘠薄等障碍问题,以该区域典型县域禹城市为研究对象,综合运用GIS和非参数地质统计学的指示克立格法,对0-20 cm深度的耕地土壤盐分和有机质的空间变异性进行了分析,并给出了土壤盐分和有机质满足一定阀值条件的概率分布图。结果表明,土壤盐分和有机质采用指示克里格方法都可以获得较为稳健的变异函数;受结构性因素与随机性因素共同影响,它们的指示半方差均表现为中等强度的空间自相关性,且单元指示克里格与多元指示克里格插值结果表明,土壤盐分、有机质的概率分布存在空间上的规律性与相似性;在空间分布上,研究区域土壤盐分含量高和有机质含量低的高概率区域主要分布在西北部的张庄镇、西部的房寺镇以及南部的莒镇乡等地区,该区域有一定的次生盐渍化风险;而土壤盐分含量高和有机质含量低的低概率分布区域主要分在徒骇河流经的河滩高地,土壤类型为褐土化潮土,是研究区域的主要高产区,基本无盐渍化。研究获取的综合指示概率分布图和概率风险评价对土壤可持续利用管理具有重要意义,为区域土壤质量的提高和土壤障碍因子消减提供参考。     

Effects of wildfire and permafrost on soil organic matter and soil climate in interior Alaska

The influence of discontinuous permafrost on ground‐fuel storage, combustion losses, and postfire soil climates was examined after a wildfire near Delta Junction, AK in July 1999. At this site, we sampled soils from a four‐way site comparison of burning (burned and unburned) and permafrost (permafrost and nonpermafrost). Soil organic layers (which comprise ground‐fuel storage) were thicker in permafrost than nonpermafrost soils both in burned and unburned sites. While we expected fire severity to be greater in the drier site (without permafrost), combustion losses were not significantly different between the two burned sites. Overall, permafrost and burning had significant effects on physical soil variables. Most notably, unburned permafrost sites with the thickest organic mats consistently had the coldest temperatures and wettest mineral soil, while soils in the burned nonpermafrost sites were warmer and drier than the other soils. For every centimeter of organic mat thickness, temperature at 5 cm depth was about 0.5°C cooler during summer months. We propose that organic soil layers determine to a large extent the physical and thermal setting for variations in vegetation, decomposition, and carbon balance across these landscapes. In particular, the deep organic layers maintain the legacies of thermal and nutrient cycling governed by fire and revegetation. We further propose that the thermal influence of deep organic soil layers may be an underlying mechanism responsible for large regional patterns of burning and regrowth, detected in fractal analyses of burn frequency and area. Thus, fractal geometry can potentially be used to analyze changes in state of these fire prone systems.     

Specific features of soil organic matter in forest landscapes of Karelia

The organic matter reserves and the soil humus state are assessed in three types of landscapes of the middle taiga (Karelia). Peat soils are the main organic matter reservoir. Hence, the greater their area, the higher the organic matter reserves in a particular landscape. The organic matter stocks in the group of semihydromorphic and hydromorphic soils clearly correlate with the degree of their waterlogging. The distribution of organic matter reserves within these soils depends on the ratio between the areas of boggy forests and open mires. The forest supporting quality of the soil is related to the organic matter composition and parent rock (the properties of the soil mineral horizons) rather than to the organic matter stocks. The data obtained may be used for assessing the forest supporting qualities of the soils and the basis for estimating the carbon budget in the landscapes.     

长江下游江心洲土壤颗粒特征及分形规律

研究了长江下游马鞍山段成长型江心洲洲头、洲中央和洲尾3个部位100cm深度范围内的土壤颗粒特征及分形规律。结果表明:江心洲土壤颗粒总体偏砂性,主要由粉粒、极细砂和细砂组成,颗粒最大粒径为350μm;在剖面上,3类颗粒的比例洲中央部位变化较小,洲头和洲尾变化较大;颗粒随深度的增加逐渐变粗;粉粒平均含量表现为洲中央>洲头>洲尾,分别为75.42%、43.58%和22.13%;土壤颗粒分形维数表现为洲中央>洲头>洲尾,分别为2.28、2.17和2.05,小于安徽省耕作表层土壤的分形维数平均值,与单位体积比表面积呈极显著正相关,与粘粒、粉粒含量极显著正相关,与极细砂、细砂极显著负相关。江心洲不同部位的土壤颗粒特征与江心洲的发育演变之间存在对应关系。     

The spatial distribution of soils across Europe: A fractal approach

In this work we investigate the applicability of fractal modeling to the soil surface system in Europe, as described by the European Soil Database (V2.0) and the soil classification of the World Reference Base [FAO, 1999. World Reference Base for Soil Resources. ISSS–ISRIC–FAO, Rome, World Soil Resources Report No. 84]. Firstly, we observe the power law patterns of the distribution of pedotaxa as well as their pedorichness–area relationships. After this, we consider the 45 most abundant soils that cover 92% of the surface of Europe and estimate the box-counting fractal dimension of the areas covered by each of the pedotaxa within three orders of magnitude. Our analysis shows a remarkable scaling behavior of soil distribution and strongly suggests the fractal nature of pedotaxa distribution across Europe. These findings lead us to propose that considering the pedotaxa fractal dimension could play an important role in the analysis of the complexity of European soil systems.     

长江源区高寒草原和高寒草甸土壤粒径分布特征

为探究长江源区主要下垫面土壤空间异质性与粒径分布(PSD)非均匀性,运用分形理论描述高寒草原和高寒草甸2种下垫面土壤粒径分布特征,分析了2种下垫面土壤的分形维数特征差异及其与土壤颗粒组成的关系。结果表明: 研究区土壤颗粒粒径主要分布于100～800 μm,高寒草原土壤单重分形维数(D_V)为2.429～2.508,高寒草甸土壤D_V为2.697～2.743,高寒草原土壤质地偏粗,高寒草甸土壤质地偏细。土壤在20～30 cm深度质地最细,在0～10 cm层质地最粗糙;多重分形维数(容量维数D₀、信息熵维数D₁、关联维数D₂)均以高寒草原(0.896～0.961、0.828～0.887、0.725～0.819)高于高寒草甸(0.890～0.914、0.693～0.744、0.540～0.603),与高寒草甸相比,高寒草原土壤粒径分布范围更宽,土壤整体构造更复杂,土壤整体非均匀性更高。D_V与土壤黏粒、粉粒含量呈显著正相关,与砂粒含量呈显著负相关;D₁、D₂与黏粒、粉粒含量呈显著负相关,与砂粒含量呈显著正相关。土壤砂粒含量是土壤PSD非均匀分布及分形维数大小变化的主要因素。     

废弃盐田复垦利用后土壤盐分与有机质含量空间变异特征

针对目前莱州湾南岸废弃盐田复垦过程中存在的土壤盐碱、瘠薄等障碍问题,以该区两个典型复垦地块为研究对象,综合运用经典统计学和地质统计学的克立格法,研究不同复垦年限下各层土壤盐分和表层土壤有机质的空间变异性,对二者进行相关性分析,并绘制了各土层盐分和表层土壤有机质含量的空间分布图。结果表明:两个区域各层土壤含盐量较高,均超过1g/kg;受复垦年限、土地平整水平和施肥等人为复垦措施影响,二区土壤含盐量明显低于一区;两个区域土壤有机质含量普遍较低,其中一区为4.37g/kg,二区为3.66g/kg;两个区域各层土壤含盐量和表层土壤有机质变异系数在32.79%—83.83%之间,在水平方向上呈中等变异强度;相关性分析结果表明各层土壤含盐量与有机质含量均呈极显著负相关;各土层土壤含盐量和有机质含量的块基比均小于25%,表明二者具有强烈的空间相关性;空间自相关距离最小为440m,超过采样间距(最小为160m),表明采样间距设置合理;Kriging插值结果表明两个区域土壤含盐量和有机质含量呈条带状分布;一区土壤含盐量以中部为高值区逐渐向南北部降低,二区土壤含盐量则以东南部最低,逐渐向西北部高值区过渡;一区土壤有机质含量表现为中部低南北部较高,二区则为东南部最高,中北部含量较低。研究结果为后期高含盐量的水盐运移模拟研究提供初步论证,也为盐田复垦区盐渍土的合理分区,改良利用和科学管理提供了技术支撑。     

异质景观条件下江汉平原土壤的空间分异

景观异质与土壤分异息息相关。以DEM数据为基础,以海拔50m、100m为界,将江汉平原划分为平原湖区景观、平缓岗地景观及起伏丘陵景观3种类型。在ArcG IS 10支持下,将江汉平原土壤图与景观类型图进行叠置分析,提取不同景观类型片区各土壤亚类斑块周长、面积等信息,计算了各景观类型片区各土壤亚类的分维数、平均斑块面积、稳定度等信息,定量分析了江汉平原各景观类型片区土壤空间分异特征,结论如下:(1)不同景观类型区各土壤亚类分布差异明显,起伏丘陵景观区主要以红壤和黄棕壤地带性土壤为主;平原湖区潮土和水稻土等耕作土非常发育;平缓岗地区地带性土壤和耕作土壤平分秋色。(2)连片性较好的土壤亚类呈现不同的景观选择性:耕作土集中分布于平原湖区景观片区;地带性土壤多集中分布于丘陵和岗地景观片区。(3)平原湖区面积很大,各类土壤都有发育的空间,土壤亚类之间分维数和稳定度差别比较大;平缓岗地景观区由于面积非常局限,土壤亚类发生发育受到空间的限制,边界破碎化,分维数平均都比较大,斑块镶嵌结构均比较复杂,稳定度差别较小。(4)主要土壤亚类的分维数和稳定性指数值一定程度地反映了各主要土壤亚类的最匹配的景观类型,即能够提供其发生发育的最佳条件。研究有利于深入认识土壤形成和演化规律,为土壤资源的合理利用及定向培育服务。     

The retention of organic matter in soils

The turnover of C in soils is controlled mainly by water regimes and temperature, but is modified by factors such as size and physicochemical properties of C additions in litter or root systems, distribution of C throughout the soil as root systems, or addition as litter, distribution of C within the soil matrix and its interaction with clay surfaces.Soil factors which retard mineralization of C in soils are identified from correlations of C contents of soils with other properties such as clay content and base status. The rate and extent of C mineralization depends on the chemistry of the added organic matter and interaction with clays of the microbial biomass and metabolites.The organomineral interactions are shown to depend on cation bridges involving mainly Ca in neutral to alkaline soils, Al in acid soils and adsorption of organic materials on iron oxide surfaces. The various organomineral interactions lead to aggregations of clay particles and organic materials, which stabilizes both soil structure and the carbon compounds within the aggregates.     

基于多光谱遥感影像的表层土壤有机质空间格局反演

利用多光谱LandSat TM遥感影像反演辽宁省阜新镇表层土壤有机质的空间格局,筛选出与土壤有机质分布相关的TM波段,分析并确定表层土壤有机质含量与TM1、TM2、TM3、TM4、TM5、TM6、TM7波段亮度值(digital number,DN)的相关关系,建立了土壤有机质含量的光谱预测模型.结果表明:研究区表层土壤有机质含量与TM4、TM5波段DN值呈极显著的负相关关系(r分别为-0.617和-0.623,P0.001),与TM3、TM5波段DN值之间满足负二次多项式回归关系(R2=0.9134,P0.001);基于TM3、TM5波段DN值的回归模型对研究区表层土壤有机质含量的预测结果可靠(R2=0.9151,P0.001).研究区表层土壤有机质含量10g·kg-1的农田主要分布在山地边缘地带,而平坦地区农田表层土壤有机质含量一般10g·kg-1,部分达到15～20g·kg-1.     

科尔沁沙地农田沙漠化演变中土壤颗粒分形特征

研究了科尔沁沙地农田沙漠化过程中土壤的粗粒化和养分的贫瘠化特征 ,土壤颗粒分形维数的变化特征 ,以及分形维数与土壤性状的关系。结果表明 :土壤沙粒含量越高 ,土壤分形维数越低 ,表征农田沙漠化程度越高 ;土壤颗粒分形维数与土壤有机 C、全 N、粘粉粒含量之间存在显著的线性关系。说明分形维数能很好地表征农田沙漠化演变中土壤结构和养分状况以及沙漠化的程度 ,可作为评价土壤沙漠化演变的一项综合性定量指标。     

Fundamental Study of Thermal Treatment of Soil

Morphological and chemical changes exhibited by different types of soils heated to different final temperatures are reported. Beds of soils were heated (in a helium atmosphere) from ～20°C to final temperatures, ranging from between 200 to 900°C, simulating ex situ thermal treatments in a nonoxidizing media. Structural changes exhibited by the soil samples during the treatments were analyzed by SEM, measurement of surface area, and measurement of particle porosity. The soil chemical transformations were quantified by means of soil weight loss, light gases yields, and carbon conversion. Soils with low organic matter content do not undergo important structural and chemical changes during the thermal treatment. On the other hand, soils with high organic carbon content suffer significant chemical modifications and, as a consequence, noticeable structural transformations. Indeed, for thermal treatments of about 900°C, weight losses as high as 22?wt%, final surface area of one order of magnitude higher than its original value (untreated soil), and changes of porosity as high as 27% were found for soils of high organic matter content. Simple mathematical equations are proposed to predict the soil weight loss and particle porosity as a function of the treatment temperature. The models provide a good fit to the experimental data.