六盘山典型植被类型土壤中石砾对大孔隙形成的影响

六盘山山区土壤中存在大量的石砾,对土壤大孔隙的形成具有重要影响。为了深刻了解和评价土壤中石砾对大孔隙形成的可能作用,本研究分析了六盘山典型植被类型下土壤中的石砾体积含量、大孔隙度变异以及石砾体积含量对大孔隙度、大孔隙半径与密度的影响。结果表明,石砾含量增加导致土壤大孔隙的平均半径和体积增大,特别是导致半径大于1.4 mm的大孔隙密度的增大,但对较小半径的大孔隙密度影响不大;总体上,石砾对土壤大孔隙度的形成影响随土深的增加而越来越明显,说明六盘山地区土壤的大孔隙明显同时受到生物因素和石砾含量因素的影响。     

Prediction of railway ground vibrations: Accuracy of a coupled lumped mass model for representing the track/soil interaction

Recent advances in railway-induced ground vibrations showed that the track/soil interaction plays an important role in the low frequency range. This paper contributes to the numerical analysis of train/track/foundation dynamics by presenting the accuracy of a coupled lumped mass (CLM) model devoted to the railway foundations and to the track/soil coupling. Following a summary of the background and the advantages of the CLM model, the coupling strategy is quantified through two application cases. Firstly, the dynamic track deflection is calculated for different railway lines considering various degrees of complexities of foundations. Then, the foundation responses are compared depending on whether detailed coupling is introduced or not. The benefit of the proposed model is emphasized by presenting free-field ground vibration responses generated by a tram and a high-speed train, obtained by a revisited two-step prediction model developed by the authors.     

生物土壤结皮对一年生植物影响研究进展

生物土壤结皮在荒漠地区广泛分布,它的形成和演替深刻地改变了土壤表层的结构特征和理化性质,进而影响了荒漠地区一年生植物的种子传播、萌发、幼苗存活及生长过程。本文回顾了国内外有关生物土壤结皮对一年生植物影响的研究,综述了生物土壤结皮对一年生植物的土壤种子库、种子萌发、幼苗存活及生长过程的影响,分析了各研究结论中存在争议的原因,总结了生物土壤结皮对一年生植物种子传播、萌发、幼苗存活及生长影响的内在机理,指出了生物土壤结皮对荒漠地区植被组成的筛选作用,并对进一步的研究进行了展望。     

紫色丘陵区不同侵蚀沉积地段土壤结构特征

以中国科学院盐亭紫色土农业生态试验站小流域为例，研究不同土壤侵蚀沉积地段（斜坡和沟谷不同部位）的土壤结构特征，以了解侵蚀沉积对土壤结构的影响。结果表明，在植被覆盖较好的坡体顶部，土壤侵蚀较弱，团聚度达到30．1％，MWD变化为3．4mm，土壤结构良好；沟谷底部由于沉积而有较多细土物质并具有适宜的水分条件，有利于土壤团聚体的形成，结构状况亦较好，团聚度达到50．3％，结构保持率为35．4％；而坡腰侵蚀较严重，团聚度仅为13．6％，结构保持率为14．1％，土壤结构状况较差。     

Spatial variation and driving mechanism of soil organic carbon components in the alluvial/sedimentary zone of the Yellow River

Alluviation and sedimentation of the Yellow River are important factors influencing the surface soil structure and organic carbon content in its lower reaches. Selecting Kaifeng and Zhoukou as typical cases of the Yellow River flooding area, the field survey, soil sample collection, laboratory experiment and Geographic Information System(GIS) spatial analysis methods were applied to study the spatial distribution characteristics and change mechanism of organic carbon components at different soil depths. The results revealed that the soil total organic carbon(TOC), active organic carbon(AOC) and nonactive organic carbon(NOC) contents ranged from 0.05–30.03 g/kg, 0.01–8.86 g/kg and 0.02–23.36 g/kg, respectively. The TOC, AOC and NOC contents in the surface soil layer were obviously higher than those in the lower soil layer, and the sequence of the content and change range within a single layer was TOCNOCAOC. Geostatistical analysis indicated that the TOC, AOC and NOC contents were commonly influenced by structural and random factors, and the influence magnitudes of these two factors were similar. The overall spatial trends of TOC, AOC and NOC remained relatively consistent from the 0–20 cm layer to the 20–100 cm layer, and the transition between high-and low-value areas was obvious, while the spatial variance was high. The AOC and NOC contents and spatial distribution better reflected TOC spatial variation and carbon accumulation areas. The distribution and depth of the sediment, agricultural land-use type, cropping system, fertilization method, tillage process and cultivation history were the main factors impacting the spatial variation in the soil organic carbon(SOC) components. Therefore, increasing the organic matter content, straw return, applying organic manure, adding exogenous particulate matter and conservation tillage are effective measures to improve the soil quality and attain sustainable agricultural development in the alluvial/sedimentary zone of the Yellow River.     

European digital archive on soil maps (EuDASM): preserving important soil data for public free access

Abstract

Historical soil survey paper maps are valuable resources that underpin strategies to support soil protection and promote sustainable land use practices, especially in developing countries where digital soil information is often missing. However, many of the soil maps, in particular those for developing countries, are held in traditional archives that are not easily accessible to potential users. Additionally, many of these documents are over 50 years old and are beginning to deteriorate. Realising the need to conserve this information, the Joint Research Centre (JRC) and the ISRIC-World Soil Information foundation have created the European Digital Archive of Soil Maps (EuDASM), through which all archived paper maps of ISRIC has been made accessible to the public through the Internet. The immediate objective is to transfer paper-based soil maps into a digital format with the maximum possible resolution and to ensure their preservation and easy disclosure. More than 6,000 maps from 135 countries have been captured and are freely available to users through a user-friendly web-based interface. Initial feedback has been very positive, especially from users in Africa, South America and Asia to whom archived soil maps were made available to local users, often for the first time. Link: http://eusoils.jrc.ec.europa.eu/library/maps/country_maps/list_countries.cfm     

Assessment of Terrestrial Ecosystem Sensitivity and Vulnerability in Tibet

The Tibetan Plateau serves an important shelter function for the ecological security of Asia, and especially China. Here, we proposed and improved indicators and methods for assessing the ecological sensitivity and vulnerability of the terrestrial alpine Plateau ecosystems and assessed the freeze-thaw erosion, land desertification, water-caused soil loss, and land salinization sensitivity, together with ecological vulnerability, from the overall ecological sensitivity, ecological pressure, and elasticity aspects in Tibet. The results indicate that the terrestrial ecosystem of Tibet is quite sensitive to freeze-thaw erosion, land desertification and water-caused soil loss. Extremely and highly sensitive regions account for 9.62% and 83.69%, respectively, of the total area of the Tibet Autonomous Region. Extremely and highly vulnerable areas account for 0.09% and 52.61%, respectively, primarily distributed in the Himalayan and Gangdise mountain regions in west Tibet; the Nyainqentanglha, Tanggula, Hoh Xil, and Kunlun mountain regions; and the northwest and northern regions of the Changtang Plateau. The results will aid the development of customized protection schedules according to different ecological issues in each region.     

科尔沁沙质草甸土壤微生物数量的垂直分布及季节动态

通过对中国农牧交错带科尔沁沙质草甸土壤微生物数量的垂直分布及其季节动态的研究分析表明:(1)微生物总数、细菌和放线菌数量均表现出与降雨量同步的季节动态,即6月份较5月份有所减少,7月份增至最多,7月份以后微生物数量逐渐下降,真菌则表现出从5月份到8月份一直增加,9月份开始回落;(2)土壤微生物具有明显的垂直分布差异.细菌和放线菌的垂直分布表现出随土壤深度增加逐渐减少的趋势,真菌数量表层最高,20 cm以下变化不够规律;(3)土壤微生物的层化比率均大于2(5月份放线菌除外);(4)不同土壤生态因子对微生物的影响不同,相同因子对不同微生物类群的影响也不相同.细菌受水分影响较大,真菌与地温的变化趋势相近,放线菌与水热条件的共同作用有关.土壤养分(有机碳和全氮)与微生物数量呈显著的正相关.     

紫色土经济林栽培技术

为了合理开发利用紫色土 ,保护生态环境 ,为紫色土经济林栽培提供实践指导 ,对紫色土经济林栽培技术进行了研究 测定了全垦、带垦、水平梯土、水平梯土撩壕、鱼鳞坑等 5种整地方法的土壤以及对照地 (不整地 )的土壤侵蚀量 ,观测了各种整地方法对经济林木生长发育的影响 ,同时 ,对栽植在紫色土和板页岩红壤上的经济林木的生长发育情况进行了对比 结果表明 :不同整地方法土壤侵蚀量按从大到小的顺序排列为全垦 (81 4t·hm-2a-1,以下单位均为t·h-2 a-1) >带垦 (63 6) >水平梯土 (3 8 7) >水平梯土撩壕 (3 1 8) >鱼鳞坑 (2 4 3 ) >对照(2 1 1) ;不同整地方法对经济林木生长发育的影响按由好到差的顺序排列为水平梯土撩壕、水平梯土、全垦、带垦、鱼鳞坑、对照 ;在一般抚育管理条件下 ,在紫色土坡地生长发育较好的树种或品种有板栗、枣树、杨梅、枇杷、萘李、甜柿、水蜜桃 ,生长发育一般的树种有茶树、无核蜜柑、柚子 ,生长发育较差的树种有脐橙、柑、葡萄 因此 ,在坡度不大 (<2 5°)的紫色土坡地营造经济林时 ,整地方法采用水平梯土撩壕为宜 ,栽培树种可选择板栗、枣树、杨梅、枇杷、萘李、甜柿、水蜜桃 ,还可选择无核蜜柑、茶树、柚子等     

1971-2010年若尔盖湿地潜在蒸散量及地表湿润度的变化趋势

利用若尔盖、红原、玛曲3个气象站1971-2010年的地面气象观测资料,根据Penman-Monteith模型计算了若尔盖湿地的潜在蒸散量,发现若尔盖湿地年潜在蒸散量呈明显上升的趋势,上升趋势为9.1 mm/10a;若尔盖湿地潜在蒸散量在2001年出现了增大突变,2001-2010年平均潜在蒸散量比1971-2000年上升了28.6 mm;各季节潜在蒸散量均呈上升趋势,其中以秋季上升最明显,上升趋势为4.3 mm/10a。导致若尔盖湿地潜在蒸散量上升的主要气象因子是温度上升、相对湿度下降和降水量的减少,虽然日照时数减少和风速减小有利于潜在蒸散量的下降,但由于气温上升的趋势更明显,影响更大,所以若尔盖湿地潜在蒸散量呈明显的上升趋势。近40 a若尔盖湿地地表湿润度以-0.03/10a的趋势减小,其中2001-2010年比1981-1990年下降了0.11,下降十分明显;与此同时,年平均气温以0.41℃/10a的趋势上升,降水量以-13.5 mm/10a的趋势减少,虽然若尔盖湿地仍属于湿润区,但出现了明显的暖干化趋势。