黄土高原南部全新世土壤微结构形成机理探讨

通过对黄土高原南部不同剖面土壤微结构的研究和与相邻地区的对比 ,探讨了风化成土过程的特征 ,揭示出全新世土壤S0 是由上下两个土壤层组成的复合土壤 ,显示两个较完整的成土过程。早期成土阶段形成了具棕壤特征的古土壤S0 2 ,晚期成土阶段形成了淋溶褐土型古土壤S0 1 。土壤S0 以上的部分是风尘堆积增强时期形成的风积黄土层 ,但被人类耕作活动所扰动。     

Soils and landscape evolution of eolian plains: the Southern High Plains of Texas and New Mexico

Sheets of eolian sediment cover many areas of the earth's surface, sand seas, dune fields, and loess sheets being the best known examples of such features. Less well known are deposits of sandy, eolian sediment forming extensive plains. An excellent example of such a region is the semi-arid Southern High Plains (northwest Texas and eastern New Mexico). The level landscape of the area was created by deposition of multiple, extensive (≈ 80,000 km²) sheets of eolian sediment (Blackwater Draw Formation) over the past 1.4+ Ma. This deposit grades from sandy (southwest) to silty and clayey (northeast) and is up to 27 m thick. Surface soils (at least 30,000 and possibly 120,000 years old) are well developed (5YR hues, agrillic horizons, 1–2m thick with prismatic structure, Stage II–III calcic horizons) and are generally Paleustolls and Paleustalfs, with some Paleargids and Haplargids. Morphologic variation is due mainly to textural variation of the eolian parent material, although locally thickness of the parent material and wind erosion and cumulization are important factors, and locally slight variation in effective precipitation may be significant. The Blackwater Draw Formation contains as many as six well-developed buried soils, each formed in individual layers of eolian sediment, similar to or more strongly expressed (2.5YR hues, higher illuvial clay content) than the regional surface soils. The presence of the buried soils indicates that sedimentation was episodic and separated by long periods of relative landscape stability. Eolian processes also appear to have been important during the periods of stability and pedoenesis by providing clayey, calcareous dust that was added to the soil, promoting formation of the argillic and calcic horizons. The sedimentologic and pedologic uniformity of the deposit suggests that the regional environment has not varied significantly during the Quaternary except for periods of increased sedimentation or wind deflation. Underlying the Blackwater Draw Formation is an Upper Tertiary deposit (up to 36 m thick) of eolian sand, silt, and clay (Ogallala Formation). This deposit contains buried soils very similar to those in the Blackwater Draw Formation, suggesting that the geomorphic processes that created the Quaternary landscape of the Southern High Plains began to operate in the late Tertiary, perhaps as much as 11 million years ago.     

北亚热带江淮地区白浆化土壤的发生学特性

通过孢子花粉、石英砂颗粒和土壤微形态学分析,研究北亚热带江淮地区白浆化土壤的发生学特性。白浆化土壤下部土体经历了暖温带森林草原景观和亚热带草原景观,为高能化学环境。在母质沉积后,经历了褐土化过程或其他物质堆积,经过一定时期的沉积间断后,堆积新物质,随着气候的变化,成土环境演变为现代气候类型,属亚热带森林草原环境。淀积层也源于黄土状物质,风化程度更强,白浆层则为后期堆积物,不具备高能化学环境。淀积层在高能环境下,存在次生粘化和淀积粘化作用。     

Soil heterogeneity and the distribution of desert and steppe plant species across a desert-grassland ecotone

Bouteloua gracilis (Kunth) Lag. ex Griffiths (blue grama), Bouteloua eriopoda (Torr.) Torr. (black grama), and Larrea tridentata Coville (creosotebush) are dominant plants on the McKenzie Flats portion of the Llano de Manzano landform within Sevilleta National Wildlife Refuge in central New Mexico, part of the biome ecotone from the Colorado Shortgrass Steppe to the Chihuahuan Desert. In this study, we examine the hypothesis that soil heterogeneity, determined by variation in surface soil depth, carbonate accumulation, and fine-textured fraction, controls relative dominance of the three species. The area is flat, generally <1% slope; however, abrupt soil differences exist even within the flattest parts of the landscape that correspond to the pattern of buried channels incised in a petrocalcic horizon (caliche) formed in a 0.5–1.2 million year-old paleosol beneath the current surface soil. Multivariate analyses of soil-moisture-related variables suggest that B. gracilis, a Colorado Shortgrass Steppe indicator, dominates the buried paleochannels where Holocene surface deposits are deepest and the argillic (clay-rich) B-horizon is thickest. B. eriopoda, dominant in Chihuahuan Desert grasslands, is most abundant where the buried petrocalcic horizon lies within 40–60 cm of the surface and the argillic horizon is thinner and weakly developed. L. tridentata, an indicator of desertified Chihuahuan Desert shrubland, is dominant where the petrocalcic horizon is exposed or near the surface. This study illustrates the strong relationship between geomorphology, soil development and vegetation patterns in arid and semi-arid environments.     

泾河上游黄土高原全新世成壤环境演变与人类活动影响

通过对黄土高原腹地甘肃合水MJY-A全新世土壤剖面磁化率、粒度、全铁、TOC、TC、CaCO3等气候代用指标的测定分析。结果表明：在全新世早期,黄土高原中部地区气候虽比较温和干燥,风尘堆积速率降低,土壤发育表现为边沉积边成壤的自然过程;到了全新世中期,气候较为温暖湿润,地表植被发育,生物风化成壤作用强烈,土壤发育依旧表现为自然的成壤过程,形成深厚的古土壤-黑垆土(S0);到了全新世晚期,气候开始恶化,干旱少雨,植被急剧退化,沙尘暴频繁发生,形成的现代黄土层(L0)覆盖了土壤(S0)使之成为埋藏古土壤,土壤发育深受人类活动的影响。现代黄土高原土地资源的退化,并不全是由自然要素本身固有的规律所造成的,而是在自然要素本身变化的背景上叠加了人类活动影响的结果。     

ALPINE AND SUBALPINE SOIL PROPERTIES AS PALEOENVIRONMENTAL INDICATORS

This paper discusses the use of soils as indicators of environmental change in the alpine and sub-alpine zones of the Colorado Rocky Mountains. Textural, miner-alogical, and chemical properties of soils developed on Quaternary glacial moraines are examined. A clear discontinuity in soil properties is observed between surface and subsurface horizons. Surface horizons are commonly finer grained and less strongly weathered than subsurface horizons. The soil-property discontinuity is interpreted to be a reflection of parent-material change. Surface horizons are interpreted to have developed in eolian sediments, while subsurface horizons have developed in glacial till. The duplex soils are believed to reflect alternating changes from cold moist climates and glacial advance to cold dry climates and loess deposition. [Key words: alpine soils, alpine weathering, alpine loess, climate change.]     

黄土的形成与气候旋回划分

根据黄土土壤特征的研究和黄土地层古土壤的识别和划分,结合磁化率测定,研究了黄土剖面冷干与温湿条件下发育的古土壤的分层和代表的气候旋回变化。资料表明,黄土具有土壤的结构和淀积成分,它是在相对冷干气候条件下发育的成熟的灰黄色古土壤,能够可靠地作为冷干气候的指示;250万年来的黄土地层至少可分为51层灰黄色古土壤与50层红褐色古土壤,代表了51个生物、气候、土壤旋回和亚旋回的变化。在50万年来的温湿气候阶段中,气候波动更频繁。     

科尔沁沙地南缘虻石沟黄土地层孢粉分析与古环境的探讨

本文通过对科尔沁沙地南缘虻石沟黄土地层孢粉分析, 划出四个花粉带。Ⅰ带是榆, 榛, 蒿; Ⅱ和Ⅳ带是蒿、藜; Ⅲ带是蒿、菊科、禾本科。从中更新世至晚更新世期间植被与气候变化, 经历了榆树疏林草原(温和偏湿)→半荒漠草原(干冷)→干草原(温凉稍湿)→半荒漠草原(干冷)多次变化过程。孢粉分析表明, 我国北方黄土地层孢粉沮合特点, 由种类贫乏喜干旱的草本花粉组成, 木本花粉数量很少, 反映黄土堆积的干燥气候占主导。植被景观多半是森林草原, 疏林草原, 干草原, 榆树疏林草原, 半荒漠草原或荒漠草原型植被。     

西周沣镐遗址全新世土壤研究

根据西安西部西周沣镐遗址附近全新世土壤剖面磁化率、全铁、有机碳、Rb和Sr等指标的测定分析,揭示了与全新世环境变化相对应的成壤过程,阐明西周时代土壤和土地资源状况及人类耕作对成壤过程影响。认为全新世早期气候较温和干燥,风尘堆积速率降低,有一定生物风化成壤作用,土壤发育表现为边沉积边成壤;全新世中期气候温暖湿润,生物风化成壤作用大于风尘堆积作用,随着沉积和成壤继续,土壤层深厚,形成古土壤层(S₀);全新世晚期气候恶化,沙尘暴频繁发生,风尘堆积作用大于风化成壤作用,形成现代黄土层(L₀)覆盖了土壤(S₀),使之成为埋藏古土壤。西周时期(3000~2720a B.P.)气候干旱使环境资源恶化,土壤退化严重,当时的耕作层和古地面位于相当于黄土(L₀)下部、古土壤(S₀)顶界以上10cm的层位。     

Buried humus horizons of flooded soils of the Selenga river delta

Presented are the results derived from investigating the buried humus horizons in flooded soils of the Selenga delta. A study of the morphology, chemical properties and composition of soil humus showed that the buried horizons are the product of evolution of soil cover across the territory which serve as filtrates of substances.     

Soil-stratigraphic techniques in the study of soil and landform evolution across the Southern Alps, New Zealand

The Southern Alps lie along the convergent Pacific-Indian plate boundary. Geomorphically distinct eastern, axial and western regions reflect the east-west gradient in tectonic uplift (1 to 10 mm a⁻¹) and precipitation (600 to 10,000 mm a⁻¹). The eastern region is divided into front-ange and basin-and-range subregions. Soil-sequence studies on terraces established temporal contrasts in pedogenesis within and between eastern and western regions encompassing Entisols, Inceptisols and Spodosols. On Late Pleistocene and early Holocene terraces Dystrochrepts are persistent soils in the eastern region and Aquods in the western region. These soil sequences are used in the interpretation of relative soil age, stratigraphy and erosion history in hill and mountain drainage basins of the eastern and western regions. In the subhumid to humid eastern front-range subregion, simple soil forms occur as catenary sequences, and there is little evidence of erosion following the destruction of forests in the last millenium. Mollisols are dominant in the subhumid, and Dystrochrepts in humid areas, respectively. Soil-debris mantle regoliths date from the early Holocene and are still developing on slopes. The soil pattern on mountain slopes in the humid, eastern basin-and-range subregion is a complex array of simple, eroded, composite and compound soils. This pattern has resulted from erosion following forest destruction within the last millenium. The oldest surface or buried forest soils are Dystrochrepts dating from the Late Pleistocene to early Holocene. Wind erosion of these low-fertility soils contributes to the loessial sediments in which younger soils have formed. In the western region, soil patterns and soil stratigraphy indicate continous instability with a complex pattern of highly leached, shallow Orthents and bedrock outcrops on slopes. The soils are eroded from slopes within 2 ka. These contrasts in soil development and erosion periodicity in the eastern and western regions of the Southern Alps parallel the east-west contrasts in erosion rates of ca. 1–10 mm a⁻¹.     

Use of soil horizons for assessing soil degradation and reconstructing chronology of degradation processes: the case of Mwisanga Catchment, Kondoa, central Tanzania

This paper analyses the use of soil horizons for mapping soil degradation intensity and reconstructing chronology of degradation processes. Through “Pedogenetic Baseline Approach”, the catchment was classified into two categories: the erosional and depositional zones. The eroded soils were reconstructed even in those areas where there had been total soil stripping. Profiles of the undegraded soil provided a reference mark (particularly the argillic B horizon of Lixisols). One specific criterion for determining the degree of soil degradation of a given map unit in the erosional zone was based on whether A or B horizons or both had been eroded. Another criterion for classifying the units in the depositional zone was based on relating the quality of the buried soil with the overlying young soil developed from the colluvium/alluvium. Hence, the study underscores the importance of being able to reconstruct soil properties of pre-eroded soil profiles with the view to determining erosion units. This will eventually help in developing appropriate land use and conservation strategies.     

海南岛北部玄武岩上土壤发育过程的定量研究

随着土壤的发育，土壤形态亦会出现相应的变化。对海南岛北部玄武岩上发育的不同成土年龄土壤系列的研究表明，土壤形态特征及其定量化指数，如红化率指数、剖面相对发育指数、土层指数、剖面发育指数等能够较好地反映土壤发育程度和土壤发育的相对年龄，其中剖面发育指数的批示效果最好。     

The soils of Culbin forest, Morayshire: their evolution and morphology, with reference to their forestry potential

A brief account of the environmental conditions within Culbin forest is provided as a background to tracing the evolution of the area since late Glacial time. Where possible, the events are placed in historical order and the development and morphological characteristics of the soils are discussed.With the exception of the humus podsols, which are developed on an old dune system, the soils lack profile development. However, since the establishment of a tree canopy, soil horizon development has been initiated and a weakly developed iron podsol has been extensively mapped. Otherwise, the soils are classified as regosols. with some low-lying soils assigned to a gleyic subgroup. The widespread occurrence of buried peat and alluvial horizons was noted during fieldwork, and mapping units that incorporate these important horizons have been separated.Investigation into the potential of each of the mapping units for forestry reveals that where buried horizons are present significant increases in yield class can be anticipated: elsewhere nitrogen and general nutrient deficiency have seriously affected tree growth, which is only mediocre in performance. However, recent work has shown that a dramatic increase in yield class can be brought about with the application of fertilizer.     

The relevance of humus forms for land degradation in Mediterranean mountainous areas

In the Gavarras (NE Spain), a large number of plots on respective schists, leucogranite and granodiorite was studied for their soils and vegetation. Results were used to check conclusions from earlier studies of Mediterranean forest soils (mostly shallow Regosols and Cambisols) on such acidic to intermediate rocks. They confirmed that the humus form depends on catenary position and lithology, and that aggregate stability and infiltration characteristics of the upper mineral soil horizon relate to humus form type. Aggregate stability of the topsoil was found to be relatively high in mor and mull type humus forms, but differences with moder type humus forms were not statistically significant. Differences in aggregate stability are attributed to the presence of stable humus–clay–iron complexes in mulls and to high fungal activity and organic matter content of mors. Low infiltration rates were only encountered in topsoils with mor type humus form, in line with results from the earlier studies. In deeper soil horizons with low organic matter content, aggregate stability will be largely related to soil reaction and base saturation. On leucogranite and granodiorite, these were found to vary strongly, most probably largely due to local differences in fast acid neutralizing capacity (ANC_f). These local differences are primarily attributed to differences in the mineralogical composition and texture of the soil material, connected with differences in lithology and/or brought about by erosion, colluviation and soil formation. Consonant with earlier studies, it is concluded that the susceptibility of these forest soils to erosion largely depends on properties of the upper mineral soil horizon, which are controlled by or related with humus form development. General trends in the latter are clear and can be used to predict this susceptibility. In the case of land degradation, which implies a more severe erosion, deeper soil horizons are also involved. Spatial variability in properties of these horizons, relevant for degradation, is considerable and not clearly related to humus form development. Accordingly, the abovementioned trends in humus form development cannot be used to predict the susceptibility to land degradation.     

Soil development at Kongsfjorden, Spitsbergen

Soils at well-drained sites near Kongsfjorden, Spitsbergen, are described in terms of morphology as well as solid and solution phase chemistry. Decarbonation is the dominant soil process and results in high Mg and Ca concentrations in soil solutions, in negative enrichment of Fe, Al, and non-carbonate clasts in near-surface horizons, and in the accumulation of dolomitic silt horizons at depth. Coatings of reprecipitated carbonates extend into the C horizon. Several developmental pathways are suggested for well-drained carbonate soils at Kongsfjorden. In vegetation-rich areas, with calcite-rich parent material, relatively rapid (∼ 10, 000 years) carbonate dissolution precedes silicate mineral weathering. In areas of Polar Desert climate and dolomitic parent material, decarbonation is slower and the continued accumulation of dolomite silt may eventually transform the soil system to a periglacial one.     

我国水土流失典型区土壤表土结皮敏感性

表土结皮是降雨与土壤共同作用下的产物,某一土壤是否结皮、结皮的敏感程度如何,取决于该土壤的性质及所处地区的降雨情况。我国广泛分布着多种理化性质迥异的土壤,尤其是黄土、紫色土、红壤和黑土分布在我国水土流失严重的区域。但是,土壤发育表土结皮的敏感性很少见报道。本文通过分析模拟降雨试验结果及前人研究结论,提出了影响表土结皮发育敏感性的3个关键因素,并基于此对我国四大水土流失典型区土壤表土结皮的敏感性进行了分析。研究表明:细颗粒,尤其是粉粒是表土结皮发育的物质基础;团聚体稳定性是表土结皮发育快慢及程度的决定因素;高强度降雨是表土结皮发育的必要条件。黄土高原地区土壤极易发育表土结皮,四川紫色土区土壤发育表土结皮的概率大,南方红壤区除花岗岩、页岩外其他母岩上发育的土壤很难发育表土结皮,东北典型黑土不发育表土结皮,而非典型黑土易发育表土结皮。     

山区土地利用/覆被变化对土壤侵蚀的影响

本文以福建省山区为例,在对福建省水土保持实验站、建瓯市牛坑龙水土保持试验站长期观测、实验资料深入分析对比的基础之上,探讨了土地利用/土地覆被变化对土壤侵蚀的影响规律。分析结果表明,土地利用/土地覆被变化对径流的产生和土壤侵蚀有重要影响,植被的覆盖度的变化直接影响着径流系数和土壤侵蚀模数;植被的覆盖度和径流系数呈负线性关系,随着覆盖度的增加径流系数逐渐减小;植被覆盖度和土壤侵蚀模数为负指数关系,随着植被覆盖度的增大,土壤侵蚀模数急剧下降。     

青藏高原东部黄土沉积的基本特征及其环境

青藏高原东部黄土沉积分布广泛。本文对青藏高原东部较大范围内黄土沉积从地层学、年代学和沉积学等方面做了初步研究。结果表明:高原黄土属典型的风成沉积,其物质主要来源于高原本身,高原冬季风是粉尘搬运的动力。研究区黄土沉积虽始于中更新世,但目前分布最广泛的黄土沉积主要是末次间冰期以来的产物。高原黄土沉积地层的黄土-古土壤序列中蕴藏着丰富的环境变化信息,是研究高原季风演化的良好地质记录。中更新世以来,末次间冰期以前,研究区经历了11次高原冬季风强盛和11次高原夏季风占优势的时段;末次间冰期以来,共经历了6次夏季风占主导地位和5次冬季风强盛时期。     

20世纪末中国土壤侵蚀的空间分布特征

通过对中国2000年第二次土壤侵蚀遥感调查成果的分析,讨论了20世纪末中国土壤侵蚀空间分布特点。结果表明,水土流失仍然是我国持续影响面最大的环境问题。西部是我国土壤侵蚀的主要分布地区,轻度侵蚀对整个土壤侵蚀格局影响最大。水蚀的分布明显体现出地形的影响,轻度水蚀基本上分布在山地丘陵区 (含黄土地形区),严重水蚀近半分布在黄土地形区。轻度水蚀主要分布在耕地、林地、草地。严重水蚀、轻度风蚀面积均约半数分布在草地,各类草地的保护与整治均应是水、风蚀区水土保持的重要内容。土壤资源中,黄绵土是受到土壤侵蚀威胁最严重的类型。但对我国土壤侵蚀的进一步分析还需要更多对方法和相关数据分析的研究工作。