若尔盖高原退化湿地土壤有机碳储量

为了定量评价若尔盖高原泥炭沼泽湿地退化的碳储存潜力,研究通过土壤剖面法,收集了3个样点的泥炭沼泽湿地土壤样品(原始泥炭地0—200cm、中度退化沼泽湿地0—100cm和重度退化泥炭地0—100cm)。研究表明:(1)中度退化沼泽湿地(1.11±0.18g/cm~3)和重度退化泥炭地(0.72±0.04g/cm~3)土壤容重平均值较原始泥炭地增加了251.8%和129.7%;中度退化沼泽湿地(46.18±6.61g/kg)和重度退化泥炭地(87.37±6.36g/kg)土壤有机碳含量平均值较原始泥炭地降低了74.2%和51.1%。(2)土层深度为0—100cm时,原始泥炭地土壤有机碳储量较中度退化沼泽湿地(384.73±95.57t/hm~2)显著高了47.0%,而与重度退化泥炭地(518.39±33.07t/hm~2)土壤有机碳储量无显著差异;当原始泥炭地有机层增加到0—200cm后,中度退化沼泽湿地和重度退化泥炭地土壤有机碳储量较原始泥炭地(1 088.17±172.84t/hm~2)降低了64.6%和52.4%,退化湿地土壤有机碳储量的降低可能主要是土壤有机碳含量降低的原因。尽管退化湿地土壤有机碳储量下降,但仍是中国(102.89t/hm~2)和全球(116.56t/hm~2)陆地土壤有机碳储量的3~5倍,该研究可为保护与恢复若尔盖高原湿地提供科学依据。     

尕海湿地植被退化过程中土壤轻重组有机碳动态变化特征

以甘肃省甘南尕海湿地内的沼泽化草甸为研究对象,采用野外取样和室内测试相结合的方法,研究植被退化过程中土壤轻重组有机碳含量及动态变化。结果表明:不同植被退化阶段0—20cm土壤轻组有机碳含量差异显著(P0.05),表现为未退化轻度退化重度退化中度退化;20—100cm土壤轻组有机碳受植被影响较小。整个土壤剖面重组有机碳含量表现为中度和重度退化显著高于未退化和轻度退化(P0.05)。土壤轻重组有机碳含量均随土壤剖面下降显著降低(P0.05)。各退化阶段沼泽化草甸土壤轻重组有机碳均呈现出明显的时间变化,在0—20cm土层,未退化阶段轻组有机碳表现为"降—升—降"的变化趋势,即5月最高,7月和9月最低,其他各退化阶段则在6月降低并趋于稳定;20—100cm土层轻组有机碳变化幅度较小。各退化阶段土壤重组有机碳动态变化较为一致,均随时间延长呈线性下降,不同月份之间差异显著(P0.05)。说明植被退化导致轻组有机碳含量下降,重组有机碳增加,而在植被生长过程中主要消耗轻组有机碳,重组有机碳相对稳定。相关分析表明,地下生物量与土壤含水量的变化对土壤轻重组有机碳影响显著。     

尕海湿地不同植被退化阶段凋落物分解及其有机碳动态

以甘南尕海湿地不同植被退化阶段的泥炭沼泽和沼泽化草甸为研究对象,通过2013,2014两年凋落物试验分析,研究了不同植被退化过程中凋落物的分解速率及有机碳动态变化特征。结果表明:随着植被退化演替,凋落物有机碳浓度、碳绝对含量和分解速率显著下降(p0.05)。分解速率从6—9月随时间变化均呈现下降趋势,相应的分解速率在0.001 3~0.009/d之间,分解速率最大的为2013年泥炭沼泽未退化PI(0.009/d),最小为2014年沼泽化草甸中度退化SⅢ(0.001 3/d)。泥炭沼泽凋落物中有机碳平均浓度未退化PI(515.07g/kg)退化PⅡ(489.62g/kg),沼泽化草甸凋落物有机碳平均浓度未退化SI(541.26g/kg)轻度退化SⅡ(488.28g/kg)中度退化SⅢ(456.01g/kg),且两年的凋落物碳绝对含量均减小,即发生净释放;凋落物分解速率及有机碳浓度、碳绝对含量都随植被退化加深而减小。     

尕海湿地植被退化过程中土壤有机碳矿化特征

为了揭示植被退化对湿地土壤碳矿化过程的影响,以甘南尕海4种不同植被退化梯度的湿地(未退化(UD)、轻度退化(LD)、中度退化(MD)及重度退化(HD))为研究对象,采用室内恒温培养和碱液吸收法研究不同土层土壤有机碳(SOC)矿化速率和累积矿化量,结合一级动力学方程,分析土壤半矿化分解时间(T1/2)、有机碳矿化潜势(C0)等参数对植被退化的响应。结果表明:(1)不同植被退化梯度湿地SOC矿化速率在培养期内呈现出基本一致的变化趋势,表现为,培养初期(0~4天)矿化速率快速下降,且数值较高,培养中后期缓慢下降(4~41天)并趋于平稳;各培养温度下,不同植被退化梯度湿地土壤在各土层有机碳矿化速率大小均为UD>LD>MD>HD。(2)在整个培养期间,各植被退化梯度湿地土壤有机碳矿化速率均随土层加深而降低,表层0-10 cm的矿化速率(1.14~16.23 mg/(g·d))均显著高于10-20 cm(1.05~2.85mg/(g·d))和20-40 cm土层(0.94~1.26 mg/(g·d))。(3)4种植被退化梯度湿地在不同温度下的土壤有机碳累积矿化量均值排序为5°C(34.54 mg/g)<15°C(46.67 mg/g)<25°C(58.28 mg/g)<35°C(86.46 mg/g)。(4)一级动力学方程的C0值随植被退化程度增加呈递减趋势,而C0/SOC随着温度的升高而降低。因此,植被退化能显著降低高寒湿地土壤有机碳矿化速率,而气候变暖能够显著增加湿地土壤有机碳矿化量。     

甘南尕海湿地泥炭地不同退化状态下氮素的特征

[目的]分析甘南尕海湿地泥炭地不同退化状态下土壤氮素的变化特征,为尕海泥炭地的生态恢复建设以及保护和利用提供科学依据。[方法]采用野外采样与室内分析相结合的方法,研究泥炭地退化过程中表层(0—40cm)土壤氮素的变化特征。[结果]除未退化土壤外,其他3种退化类型的土壤全氮含量均为9月显著高于7月,而土壤C/N比与土壤全氮变化恰好相反;土壤各相应层铵态氮含量7和9月基本呈相同的变化趋势;0—20cm层土壤速效氮9月显著高于7月,20—40cm层(除中度退化)恰好相反。从剖面分部上看,土壤全氮在20—40cm层富集;土壤C/N比和速效氮含量基本在20—40cm层富集;除中度退化外,土壤铵态氮在0—20cm层富集。[结论]4种退化阶段的泥炭地土壤全氮含量具有明显的时间变化,说明植被对尕海泥炭地的恢复具有十分重要的作用。     

植被恢复对昆阳磷矿土壤有机碳储量的影响

植被恢复是既能保持磷矿开采同时又能有效扼制矿区生态环境的退化,并逐步恢复已退化的矿区生态系统最有效的生物措施。为揭示植被恢复对昆阳磷矿土壤有机碳和碳素积累的影响,研究探讨了昆阳磷矿不同恢复林地的土壤有机碳储量变化。结果表明:（1）不同恢复林地的土壤有机碳含量存在显著差异（p < 0.05）,7种不同植被恢复人工林土壤平均有机碳含量分别是废弃地的14.29倍、11.83倍、11.40倍、5.89倍、15.48倍、15.59倍、18.53倍。（2）土壤有机碳在剖面的含量表现出明显的“表聚作用”,均以表土层（0—20 cm）最大,且随土层厚度的增加,呈下降趋势。（3）不同恢复林地的土壤有机碳密度差别较大,变化趋势和土壤有机碳含量的变化趋势一致,且在同一林分土壤中,单位深度土壤各土层平均有机碳密度均以表层最大,随土层的增加而降低。（4）土壤有机碳主要存储于0—20 cm土层中,平均含量为53.60%,随着土层的加深,土壤有机碳所占比重急剧下降,经过植被恢复,7种人工林土壤有机碳储量较废弃地0—20 cm土壤有机碳储量提高了26.53%,20.39%,34.48%,10.81%,28.62%,39.52%,36.71%,说明目前矿区通过植被恢复后的土壤状况显著优于未进行恢复措施的废弃地。     

湿地退化条件下土壤碳氮磷储量与生态化学计量变化特征

为了研究湿地退化过程中土壤碳氮磷储量与生态化学计量变化,明确碳氮"汇"功能的变化和土壤碳、氮、磷的平衡关系,采用实地采样调查、室内分析与数理统计法,研究了若尔盖自然湿地保护区内未退化湿地沼泽(MA)、沼泽化草甸(MM)、草甸(ME)3种不同退化程度湿地的典型样地在碳氮磷含量、储量以及生态化学计量的变化特征。结果表明,草甸化沼泽土与草甸土全剖面总有机碳、全氮含量较沼泽土分别降低了29.55%,6.52%和67.53%,40.04%,碳氮储量分别降低了67.49%,60.10%和85.14%,54.47%;3种土壤全磷剖面含量大小顺序为MMMEMA,其储量高低顺序是MEMAMM。随着土层深度的增加,沼泽土的总有机碳、全氮含量明显升高,全磷含量与草甸化沼泽土、草甸土的总有机碳、全氮、全磷含量均呈现降低趋势;3种土壤碳氮磷储量40—100cm土层高于0—40cm土层。沼泽土、草甸化沼泽土、草甸土3种不同类型土壤C/N分别为40.38,31.70,23.26,C/P分别为409.52,247.46,113.07,N/P分别为10.43,7.90,5.02,土壤C/N、C/P、N/P均随湿地退化而减小,较高的C/P与N/P14揭示氮磷元素均是影响植物生长的限制性因素,且受氮素限制高于磷素。因此,若尔盖湿地退化导致土壤碳氮含量与储量降低,碳氮"汇"功能减弱,尤其是碳"汇"。     

植被退化对尕海湿地枯落物分解的影响

[目的]分析植被退化对青藏高原东部尕海湿地枯落物分解的影响,为湿地生源要素生物地球化学循环过程研究提供基础依据。[方法]采用分解袋法,研究尕海泥炭沼泽和沼泽化草甸不同植被退化梯度湿地枯落物分解特征及其影响因素。[结果]各植被退化阶段湿地枯落物分解过程存在显著差异,植被退化总体抑制了枯落物分解,但不同湿地类型枯落物分解对植被退化响应有所不同;在生长季内(5—9月),沼泽泥炭植被未退化枯落物分解速率显著高于退化(p0.05);沼泽化草甸平均分解速率排序为:未退化(0.028 9g/d)中度退化(0.028 7g/d)轻度退化(0.028 0g/d);各植被退化阶段湿地的枯落物分解过程具有明显的年际变化特征,总体表现为2014年分解较快,2015,2016年相对较慢;温度和降雨对各退化阶段枯落物分解速率具有促进作用,但作用不显著。[结论]尕海湿地植被退化过程中枯落物分解动态受到枯落物自身性质、气候条件、土壤营养状况等自然环境条件的共同影响,相比而言,受枯落物性质的影响更大。     

草地退化对青海湖流域小蒿草草甸土壤碳密度的影响

以青海湖流域小嵩草草甸土壤为研究对象,对不同退化程度下小蒿草草甸土壤容重和有机碳含量进行了测定,并在此基础上确定了土壤有机碳密度。结果表明:随着小嵩草草甸退化程度的加剧,其土壤容重在剖面上表现为逐渐增大趋势,土壤有机碳含量从表面逐渐减小,特别是0—10 cm表层有机碳含量减少尤为明显,未退化的表层有机碳平均含量是严重退化的6.5倍。土壤有机碳密度变化与有机碳含量在4种不同退化植被土壤中表现一致;4种不同退化程度小嵩草草甸0—100 cm土壤有机碳密度分别为（10.74±3.03）,（12.41±4.15）,（8.04±6.24） kgC/m²和（4.56±0.70） kg/m²,即轻度退化 > 未退化 > 中度退化 > 重度退化,说明随退化程度的加剧,土壤有机碳密度呈现显著下降趋势,但轻度退化有助于碳积累。     

子午岭林区不同植被恢复阶段土壤有机碳变化研究

研究了子午岭林区植被恢复过程中土壤有机碳含量、团聚体有机碳分布以及不同粒级团聚体有机碳对土壤有机碳的贡献率。研究结果表明,0—100 cm剖面上有机碳含量加权平均值随植被恢复年限逐渐升高,坡耕地0—100 cm土层土壤有机碳加权平均值为3.54 g/kg,弃耕地、草地、灌木和乔木阶段分别比坡耕地提高6.8%,36.6%,41.5%和73.6%;0—20 cm土层土壤有机碳含量随植被恢复的提高幅度明显高于20 cm以下土层;0—5和5—10 cm土层土壤各粒级团聚体有机碳含量随植被恢复年限逐渐增加,并有向大粒级（〉2 mm）团聚体中富集的趋势,10—20 cm土层土壤团聚体有机碳含量随植被恢复变化不明显;弃耕地、草地、灌木和乔木阶段0—20 cm土层〉5,5～2和2～1 mm粒级团聚体有机碳贡献率高于坡耕地,说明植被恢复0—20 cm土层土壤增加的有机碳更多地固定在〉1 mm粒级团聚体中。     

Physical Properties of the Soils of Sibay City of the Republic of Bashkortostan

Eurasian Soil Science - The results of the study of the properties of urban soils of the city of Sibay located in the mining region of the Republic of Bashkortostan are presented. A specific...     

食用仙人掌萎蔫气象条件分析

塑料大棚内种植的食用仙人掌在土壤墒情较好时也有萎蔫现象发生，通过试验观测和对仙人掌生理习性的分析，发现阴雨过后天气突然放晴温度急剧上升易使仙人掌发生萎蔫现象，并提出了田间管理的应对措施。     

Heterogeneity of Organic Matter of Aggregates of Protocalcic Chernozems

Eurasian Soil Science - Layers were step-by-step removed from macroaggregates (2–1 mm in diameter) of Protocalcic Chernozems via successive abrasion in a revolving rotator during 5, 10, 15,...     

青海省耕地资源开发利用分析及对策研究

分析论述了青海省耕地资源开发利用的现状、特点和问题。在此基础上,提出了对青海省耕地资源进行研究的框架体系和思路,同时基于GIS/RS技术设计了相关的技术路线。最后依据所做设计对青海省耕地资源开发利用做了初步分析,并进行了相关的对策研究分析。     

Characterization of physical and chemical properties of Varzea soils of Goias State of Brazil

Abstract

Brazil has approximately 30 million hectares of lowland areas, known locally as “Varzea,”; distributed throughout the country. Soils in these areas have the potential to support agricultural production, but very little is known about their fertility. The current experiment was undertaken to characterize the chemical and physical properties of representative “Varzea”; soils collected at 0–20, 20–40, 40–60, and 60–80 cm depth intervals from 23 sites in Goias State of Brazil. Organic matter contents averaged 42 g/kg in the surface 20 cm of soil and should make a significant contribution to overall nutrient availability. Soil pH increased slightly with depth from a mean value of 5.2 in the surface 20 cm of soil to a mean value of 5.4 in the 60–80 cm depth interval. Several soils had exchangeable Al values ≥ 1.0 cmol Al/kg, but soil Al saturation was generally less than the 60% level frequently associated with Al toxicity. However, cereal and legume production could benefit from lime addition in many of these soils. Although base saturation was fairly low in some soils, exchangeable Ca and Mg levels were, in general, adequate throughout the profile. Extractable P levels were adequate in most surface soil samples. Extractable K levels in these soils were generally low, and the application of K fertilizers should be beneficial, especially in conjunction with lime addition. The high clay content “Varzea”; soils of the Brazilian lowlands have some drainage problems but generally exhibit favorable chemical properties for crop production when compared to soils of the well‐drained Cerrados.     

Estimation of potential nitrogen-fixing activity of agrophytocenoses soils of the subtropical zone of Russia

An estimation of potential nitrogen-fixing activity of various soil types under agrophytocenoses of tea, filbert, peach, and pawpaw which grow in the area of Greater Sochi is given. High indicators of nitrogen fixation activity in the soil in the course of vegetation were characteristic of agrocenoses of pawpaw, peach, and filbert. The lowest level of nitrogen fixation was noted in the soil of a tea plantation. A negative correlation dependence of potential nitrogen-fixing activity on the acidity of the soil solution was established. A study of the seasonal dynamics of the activity of nitrogen fixation of soils of agrocenoses of the subtropical zone of Russia made it possible to distinguish a less active winter and more active spring-summer-autumn periods.     

物联网安全及解决措施

物联网是一个集信息通信、数据交换、传感器技术与软件工程于一体的综合性产业,探讨和分析了物联网的结构体系与发展中遇到的安全问题。     

荔枝种子结构的扫描电镜观察

荔枝种子从果实中剥离出来后, 即使在室内条件下, 也极易失水干缩, 潮湿环境中又易发霉而腐烂。扫描电镜观察表明: 种皮上布满纹孔, 水分散失面积很大; 种脐部为疏松的海绵组织, 且营养丰富。据此, 生产上应对种子彻底清洗, 并保存于适当湿度的环境中, 以提高其发芽率。     

Kinetics of Popping of Popcorn

The rate of popping of popcorn was measured in oil and in air. Kinetic data for lifetimes of individual kernels from a large population were obtained in oil at six constant temperatures (180–250°C) and also in an air‐popper at 202°C. The data are characterized by an induction period, which is, significantly, followed by a first‐order decrease in the number of unpopped kernels versus time. The activation energy for the first order process is 166.7 kJ/mol between 180 and 210°C, and 53.8 kJ/mol between 210 and 250°C. These data are consistent with a model that assumes 1) that the rate of heat transfer into a kernel follows Newton's law of cooling; 2) that in a sample of kernels there exists a distribution of critical pressures; 3) that for an individual kernel, the probability of popping is directly proportional to the difference between the internal aqueous vapor pressure and the kernel's critical pressure; and 4) that the measured rate constant at any temperature is an average overall of the kernels in the sample with critical pressures equal to or less than the internal aqueous vapor pressure. Minimum popping temperatures predicted by the model are 181 ± 2°C (oil) and 187 ± 2°C (air), in good agreement with previously reported direct measurements.