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(Dv)为2.429～2.508,高寒草...     

南京市土壤集合组成及其嵌套性分析

随着工业化和城市化的加速发展,土壤资源与土壤环境压力日益增加。近20a来,南京市城镇化发展迅速,而且城镇的发展正导致原来相对自然的大片土壤面积减少,深入研究南京市土壤组成以及嵌套性特征,有助于了解土壤类型的分布特征,正确估计城镇化的后果,在保护土壤资源以及土壤多样性方面具有一定的理论意义和现实意义。以南京市各乡镇等级单位的土壤集合为研究对象,对南京市的土壤组成及嵌套性进行了分析。结果显示,在南京市各乡镇等级单位中共有47个土种,其中优势土种6种,常见土种13种、稀有土种25种、濒危土种3种。土壤集合在组成上呈现出不完全嵌套格局,分布于土种数较少的乡镇等级单位中的土种多数也分布在土种数较多的乡镇等级单位中。土壤类型数（S）与面积（A）是幂函数关系,其最佳回归拟合方程为：S=0．7284A^0.5922。嵌套格局与南京市的土种面积、地形以及地理位置关系密切,面积大的乡镇等级单位有更多的土种主要原因是它们有更广阔的生境范围,具有更高的生境多样性（如水域、沼泽、地形地貌、丘陵等）,随着面积的缩小,某些特定的生境类型随着逐渐丧失,与此相关的一些土种也随之消失,于是就产生了嵌套结构。     

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。     

退化沙质草地开垦和围封过程中的土壤颗粒分形特征

研究了科尔沁退化沙质草地开垦和围封过程中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,不同开垦和围封年限的土壤颗粒分形维数(0～30cm)介于2.387～2.588之间.随着开垦年限的增加,0～15 cm层土壤颗粒分形维数从2.441降至2.387;围封11年后,0～15 cm层土壤颗粒分形维数增加到2.588.15～30 cm层土壤颗粒分形维数无明显变化.土壤颗粒分形维数是反映土壤质地的一个较好指标,重点反映粘粒含量,其次是粉粒含量.分形维数的变化能够很好地表征退化沙质草地土壤的化学、物理和生物学性状的变化趋势,可以作为评价退化沙质草地土壤性状的一个综合指标.     

退化沙质草地开垦和围封过程中的土壤颗粒分形特征

研究了科尔沁退化沙质草地开垦和围封过程中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,不同开垦和围封年限的土壤颗粒分形维数(0～30cm)介于2.387～2.588之间.随着开垦年限的增加,0～15 cm层土壤颗粒分形维数从2.441降至2.387;围封11年后,0～15 cm层土壤颗粒分形维数增加到2.588.15～30 cm层土壤颗粒分形维数无明显变化.土壤颗粒分形维数是反映土壤质地的一个较好指标,重点反映粘粒含量,其次是粉粒含量.分形维数的变化能够很好地表征退化沙质草地土壤的化学、物理和生物学性状的变化趋势,可以作为评价退化沙质草地土壤性状的一个综合指标.     

腾格里沙漠草方格固沙林土壤颗粒组成、分形维数及其对土壤性质的影响

为了明确草方格人工固沙造林植被恢复过程中土壤颗粒组成、分形维数及对土壤理化性质的影响,以腾格里沙漠东南缘2016年(1 a)、2013年(4 a)和1987年(30 a)草方格固沙林为研究样地,以周围流动沙地为对照(CK),研究了草方格固沙造林后植被恢复过程中土壤颗粒组成、分形维数及与土壤理化性质的作用关系.结果表明: 100～250、250～500 μm土壤颗粒含量较高,分别为42.5%～80.1%、12.5%～42.2%;50～100 μm土壤颗粒含量居中,为0.2%～20.8%;<2和2～50 μm的土壤颗粒含量次之,分别在0～1.3%和0～22.7%;而500～1000 μm的土壤颗粒含量较低,在0.3%以下.<2和2～50 μm土壤颗粒仅在30 a固沙林有分布;50～100 μm土壤颗粒分布为30 a最高,4 a和1 a居中,而CK最低;100～250 μm土壤颗粒分布依次为4 a>1 a>CK>30 a;250～500 μm土壤颗粒分布为CK>1 a>4 a>30 a;但500～1000 μm土壤颗粒在各样地分布均较少,且不同样地之间无显著差异.研究区土壤颗粒分形维数为0.54～2.59,并且不同样地间存在显著差异,表现为30 a最高,4 a与1 a居中,而CK最低.土壤颗粒分形维数与土壤黏粒、粉粒、极细砂粒含量呈极显著正相关,而与土壤中砂粒呈极显著负相关.土壤颗粒分形维数与土壤电导率、有机碳、全氮和碳氮比均呈极显著正相关,而与土壤pH和含水量无相关性.土壤中<2、2～50、50～100 μm颗粒与土壤电导率、有机碳、全氮和碳氮比均呈极显著正相关,而250～500 μm土壤颗粒与上述4个土壤指标和土壤含水量呈显著负相关.500～1000 μm土壤颗粒与土壤含水量亦呈极显著负相关.在腾格里沙漠东南缘地区利用草方格进行人工固沙植被建设,可有效促进土壤颗粒细粒化,长期演变导致土壤黏粒和粉粒及土壤分形维数显著增加,促使土壤有机碳和全氮含量提高,有利于土壤理化性质改善和促进沙漠化治理.     

分形理论及其在土壤空间变异研究中的应用

土壤具有不同程度的空间变异性,土壤空间变异研究对于土壤管理有重要意义.本文简要综述了分形理论及其在土壤空间变异研究中的应用,重点讨论了利用矩方法计算土壤属性分形维,多重分形分析土壤空间变异性及基于多重分形谱参数的土壤属性尺度转换.早期研究验证了分形理论在分析土壤空间变异中的有效性和应用潜力,国内外近期研究则报道了利用分形及多重分形理论分析土壤空间变异的最新进展.分形理论可以成为量化土壤属性空间变异性及尺度转换的重要工具.     

贝壳堤岛3种植被类型的土壤颗粒分形及水分生态特征

运用土壤粒径质量分布原理与分形学理论,以黄河三角洲贝壳堤岛的3种植被类型为研究对象,以裸地为对照,测定分析土壤颗粒分形维数、粒径组成和水分物理参数,探讨不同植被类型的土壤颗粒分形特征及其影响因素。结果表明：贝壳砂土壤中粗砂粒含量最高;其次是细砂粒,而石砾和粉粘粒含量较低。灌木林地和草地具有降低石砾、粗砂粒,增加细砂粒和粉粘粒含量的作用。不同植被类型土壤颗粒分形维数均值在1.5845－1.9157之间,大小依次为酸枣林、杠柳林和草地,表层高于20－40cm土层。酸枣林、杠柳林及草地0－40cm土壤容重均值分别比裸地低23.87%,14.51%和10.47%;总孔隙度均值分别比裸地增加16.96%,16.71%和1.31%。植被恢复措施对贝壳砂表层的孔隙结构、疏松程度改善较好,草地及灌木林地的蓄水性能均表现为0－20cm高于20－40cm。土壤颗粒分形维数与粉粘粒含量、毛管孔隙度、总孔隙度、饱和蓄水量、吸持蓄水量等呈极显著正相关,与细砂粒含量呈显著正相关,与粗砂粒含量和容重呈极显著负相关,与石砾含量、非毛管孔隙度、滞留蓄水量的相关性不大。从土壤分形维数及其水分生态特征来看,贝壳堤岛3种植被类型的改良土壤物理性质及蓄水保土功能表现为灌木林好于草地,其中酸枣林好于杠柳林,0－20cm好于20－40cm土层。     

Estimating regional carbon stocks and spatially covarying edaphic factors using soil maps at three scales

Most estimates of regional and global soil carbon stocks are based on extrapolations of mean soil C contents for broad categories of soil or vegetation types. Uncertainties exist in both the estimates of mean soil C contents and the area over which each mean should be extrapolated. Geographic information systems now permit spatially referenced estimates of soil C at finer scales of resolution than were previously practical. We compared estimates of total soil C stocks of the state of Maine using three methods: (1) multiplying the area of the state by published means of soil C for temperate forests and for Spodosols; (2) calculating areas of inclusions of soil taxa in the 1:5,000,000 FAO/UNESCO Soils Map of the World and multiplying those areas by selected mean carbon contents; and (3) calculating soil C for each soil series and map unit in the 1:250,000 State Soil Geographic Data Base (STATSGO) and summing these estimates for the entire state. The STATSGO estimate of total soil C was between 23% and 49% higher than the common coarse scale extrapolations, primarily because STATSGO included data on Histosols, which cover less than 5% of the area of the state, but which constitute over one-third of the soil C. Spodosols cover about 65% of the state, but contribute less than 39% of the soil C. Estimates of total soil C in Maine based on the FAO map agreed within 8% of the STATSGO estimate for one possible matching of FAO soil taxa with data on soil C, but another plausible matching overestimated soil C stocks. We also compared estimates from the 1:250,000 STATSGO database and from the 1:20,000 Soil Survey Geographic Data Base (SSURGO) for a 7.5 minute quadrangle within the state. SSURGO indicated 13% less total soil C than did STATSGO, largely because the attribute data on depths of soil horizons in SSURGO are more specific for this locality. Despite localized differences, the STATSGO database offers promise of scaling up county soil survey data to regional scales because it includes attribute data and estimates of areal coverage of C-rich inclusions within map units. The spatially referenced data also permit examination of covariation of soil C stocks with soil properties thought to affect stabilization of soil C. Clay content was a poor predictor of soil C in Maine, but drainage class covaried significantly with soil C across the state.     

The Effect of Soil Erosion on Europe’s Crop Yields

Abstract Soil erosion negatively affects crop yields and may have contributed to the collapse of ancient civilizations. Whether erosion may have such an impact on modern societies as well, is subject to debate. In this paper we quantify the relationship between crop yields and soil water available to plants, the most important yield-determining factor affected by erosion, at the European scale. Using information on the spatial distribution of erosion rates we calculate the potential threat of erosion-induced productivity losses. We show that future reductions in productivity in Europe as a whole are relatively small and do not pose a substantial threat to crop production within the coming century. However, within Europe there is considerable variability, and although productivity in northern Europe is not likely to be significantly reduced by soil erosion, for the southern countries the threat of erosion-induced productivity declines is stronger.     

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。     

川南天然常绿阔叶林人工更新后土壤团粒结构的分形特征

运用分形模型研究了川南天然常绿阔叶林及其人工更新成檫木(Sassafras tzumu)林、柳杉(Cryptomeria fortunei)林和水杉(Metasequoia glyptostroboides)林后土壤团粒结构,探讨了分形维数与林地土壤水源涵养功能、肥力特征和微生物数量之间的关系。结果表明:天然常绿阔叶林人工更新后土壤团粒结构的分形维数和结构体破坏率增大、土壤物理性质变差、养分含量和微生物数量降低,3种人工林中,檫木林较好、水杉林次之、柳杉林最差;土壤团聚体、水稳性团聚体和水稳性大团聚体含量越高分形维数越小;在湿筛条件下,土壤结构体破坏率随分形维数的降低而减小;土壤团粒结构的分形维数与土壤物理性质、养分含量和微生物数量之间存在显著的回归关系。这表明天然常绿阔叶林人工更新后由于不同林分对林地土壤组成结构的维护效果不同,导致更新后林地土壤物理、化学和生物性质变化,林地土壤团粒结构的变化,进而影响其分形维数的大小。因此,分形维数可作为天然常绿阔叶林及其人工更新后林地土壤水源涵养功能、肥力特征和微生物活动情况的一项综合性定量化评价指标。同时,为保护天然常绿阔叶林、选择适宜的更新树种和天然常绿阔叶林人工更新后林地土壤的科学管理提供依据,也为退耕还林中树种的选择提供参考。     

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.     

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。     

Modelling applicability of fractal analysis to efficiency of soil exploration by roots

BACKGROUND AND AIMS: Fractal analysis allows calculation of fractal dimension, fractal abundance and lacunarity. Fractal analysis of plant roots has revealed correlations of fractal dimension with age, topology or genotypic variation, while fractal abundance has been associated with root length. Lacunarity is associated with heterogeneity of distribution, and has yet to be utilized in analysis of roots. In this study, fractal analysis was applied to the study of root architecture and acquisition of diffusion-limited nutrients. The hypothesis that soil depletion and root competition are more closely correlated with a combination of fractal parameters than by any one alone was tested. MODEL: The geometric simulation model SimRoot was used to dynamically model roots of various architectures growing for up to 16 d in three soil types with contrasting nutrient mobility. Fractal parameters were calculated for whole roots, projections of roots and vertical slices of roots taken at 0, 2.5 and 5 cm from the root origin. Nutrient depletion volumes, competition volumes, and relative competition were regressed against fractal parameters and root length. KEY RESULTS: Root length was correlated with depletion volume, competition volume and relative competition at all times. In analysis of three-dimensional, projected roots and 0 cm slices, log(fractal abundance) was highly correlated with log(depletion volume) when times were pooled. Other than this, multiple regression yielded better correlations than regression with single fractal parameters. Correlations decreased with age of roots and distance of vertical slices from the root origin. Field data were also examined to see if fractal dimension, fractal abundance and lacunarity can be used to distinguish common bean genotypes in field situations. There were significant differences in fractal dimension and fractal abundance, but not in lacunarity. CONCLUSIONS: These results suggest that applying fractal analysis to research of soil exploration by root systems should include fractal abundance, and possibly lacunarity, along with fractal dimension.     

黄土高原南麓县域耕地土壤速效养分时空变异

在生态脆弱的黄土高原南麓合阳县,以1983、2006年耕地土壤速效氮、磷、钾含量为对象,利用空间自相关、变异函数及分形维数等方法,研究县域土壤速效养分时空变异特征及主要影响因素.结果表明,从1983到2006年,除土壤速效钾外,耕地速效氮、磷的平均含量分别提高73.98％和92.69％;土壤速效养分全局Moran's I指数和空间相关距均呈递减变化、分维数增加,预示其空间结构减弱,随机变异性增强.土壤速效氮、磷含量在绝大部分研究区域内呈现不同程度累积,而速效钾含量则在59.65％的耕地上减少;导致其不同变化的因素有耕地利用方式、施肥管理、灌溉、土壤类型等,其中以土地利用方式和施肥管理措施的影响最大.     

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.     

Trends in soil fractal parameters caused by accumulation of soil organic matter as resulting from the analysis of water vapor adsorption isotherms

The experimental adsorption isotherms are used to evaluate the specific surface area and the surface fractal dimensions of several samples containing organic matter. The aim of the investigations has been to search for correlations between specific surface area and geometrical heterogeneity, as characterized by the surface fractal dimension and the content of organic matter. Besides natural organic soils (peats, forest humuses and brown coal from mines) we also investigate controlled systems obtained by adding humic acids to kaolin and quartz, organic compost to soils and by mixing sandy soil and peat at different ratios. The aim of the investigations of controlled systems was to discover some general trends in the dependencies of the specific surface area and the surface fractal dimension on the content of organic matter.     

黄土丘陵沟壑区撂荒地不同演替阶段植物群落的土壤抗蚀性——以坊塌流域为例

采用野外调查取样与室内试验相结合的方法,在分析土壤颗粒组成、级配状况与群体特性、团粒结构的分形特征及其稳定性变化的基础上,研究了黄土丘陵沟壑区撂荒地不同演替阶段植物群落的土壤抗蚀性.结果表明： 撂荒后植被从一年生草本群落阶段演替到多年生蒿禾类草本群落阶段的过程中,土壤的级配状况在不断改良,颗粒分形维数增大,团粒结构有所改善,土壤团粒结构的分形维数与结构体破坏率均不断减小,稳定性不断增强,从而提高了土壤的抗蚀性.实现植被的自然恢复对改善该区土壤结构、提高土壤抗蚀性、减少水土流失和促进区域生态环境可持续发展具有重要意义.