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通过广泛的野外考察,在渭河下游发现了全新世古洪水滞流沉积物,对其进行了深入观察、地层划分和系统采样。在实验室内进行磁化率、烧失量、碳酸钙和粒度成分等多指标的分析测试。结果表明,这些古洪水沉积物以细粉沙为主,性质为粉沙质亚黏土,致密坚硬,具有水平或波状层理,与覆盖在河流阶地面的风成黄土和古土壤有着显著的区别。通过OSL测年断代,发现它们与渭河上游固川镇剖面的古洪水SWD为同一期特大洪水的沉积物。这表明渭河流域在3200—3000aBP发生了一组3次特大洪水事件。这个时期正是全新世大暖期结束之际,也就是中国历史上商代末期。渭河流域特大洪水事件的发生与全球性气候恶化转折密切相关。 相似文献
3.
新构造运动对黄土高原土壤侵蚀的影响 总被引：3，自引：1，他引：3
新构造运动是影响黄土高原土壤侵蚀的主导性因素.第四纪以来,受青藏高原阶段性强烈隆升的影响,黄土高原的形成与演化也具有阶段性.黄土高原地质时期土壤侵蚀的相对强烈期为更新世早期(2.5～2.4MaB.P.)、更新世中期(1.67～1.43MaB.P.)、更新世中晚期(0.85MaB.P.)、更新世晚期(0.10～0.07MaB.P.)和全新世5个时期,其中前4个时期为自然侵蚀期,全新世为人为加速侵蚀期.新构造运动是黄土高原重力侵蚀的主要影响因素,构造弧形隆升和断隆带是黄土高原的强烈侵蚀产沙中心. 相似文献
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渭河流域全新世土壤剖面木炭屑记录及其古环境意义 总被引：1，自引：0，他引：1
通过野外采样及其磁化率、总有机碳(TOC)、木炭屑的分析,探讨全新世野火活动与生态环境演变的关系。研究结果表明:TOC并不能完全指示野火活动,木炭屑是指示野火活动的理想指标,木炭屑对生态环境演变特征具有环境指示意义。末次冰期11500aB.P.之前,渭河流域气候干旱,植被为半荒漠草原,自然野火频繁发生;全新世早期(11500～8500aB.P.)野火发生频率大大降低;全新世气候适宜期(8500～3100aB.P.),气候比较湿润,生物风化成壤作用强烈,自然野火发生几率明显下降,但不同地点人类活动引发的野火活动存在区域差异;全新世晚期近3100年以来,气候向干旱化发展,加之人类利用土地活动加剧,生物量燃烧的规模大幅度增加;1500aB.P.以后,木炭屑浓度大幅度减少,野火发生频率大大降低。可能由于渭河流域土地利用方式发生重大改变,人工自然复合生态景观基本形成,因而不再大规模放火烧荒。此外,木炭屑对人类活动的遗迹具有指示作用。 相似文献
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风沙活动、降雨和人类活动是干旱-湿润过渡区影响粗泥沙(d>0.05mm)入黄的几个重要因素。粗泥沙输沙量的变化取决于全沙输沙量和粗泥沙在全沙中所占的比例。基于悬移质输沙量和泥沙粒径构成、降雨量、沙尘暴日数和水土保持面积等数据,分析了粗泥沙输沙量与影响因素之间的关系,利用Arc-GIS和SPSS软件定量分析了影响无定河流域代表自然过程的风水两相作用和人类活动对粗泥沙输沙量的影响,并通过回归分析确定了不同影响因素对全沙输沙量和粗泥沙比例的贡献。结果表明,影响全沙输沙量的主要因素是降雨量和水土保持措施,而影响粗泥沙比例的是风沙活动和水土保持措施。利用二元回归分析确定了各因素的贡献比例,认为降雨量的减少和人类活动对全沙量减少的贡献相当,人类活动对粗泥沙比例降低的贡献高于风沙活动的作用。 相似文献
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黄土高原典型支流淤地坝拦沙对输沙量减少的贡献 总被引：2，自引：0，他引：2
为探明淤地坝拦沙作用对河流输沙量变化的影响,依据淤地坝作用年限、坝控面积、坝控流域侵蚀产沙模数及淤地坝排沙率,确定淤地坝拦沙量的估算方法,并结合2009年淤地坝安全大检查数据,分析黄土高原典型支流淤地坝拦沙对输沙量减少的贡献.延河与皇甫川淤地坝在不同年代的拦沙量分别在92.48万～854.35万t/a与36.47万～1 138.75万t/a之间,淤地坝拦沙量占人类活动影响的比例在一级和二级突变后分别为29.1％、28.5％与8.4％、18.2％;2000年以后延河与皇甫川输沙量减幅均达到85％以上,而淤地坝拦沙量的贡献率分别小于10％和20％.淤地坝的拦沙作用已不是目前输沙量减少的主要因素,但由于土壤侵蚀环境的不同,淤地坝在皇甫川对输沙量减少的贡献比在延河要大. 相似文献
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本文系统的分析研究了长江上游地面侵蚀和河流泥沙两个系统。认为长江上游地面侵蚀的发展主要受人类在农业耕作、林业开采、草原开发、修路、基建等方面不合理的社会经济活动的影响，导致长江上游水土流失面积不断扩大。同时作者还分析和预测了在禁止各种新的破坏情况下，预计到2000年按现有的治理速度，上游地区侵蚀量将由15.68亿t降到10.22亿t。分析表明：长江上游地区输移比远小于1，且受流域面积、地质地貌、地面物质组成及人为活动等多种因素的影响。通过分区预测地面侵蚀对河流泥沙的影响，认为今后在上游通过治理，使地面侵蚀量虽有较大减少，但河流泥沙的变化仍然较小，到2000年宜昌站平均悬移质输沙量将在4.88～5.02亿t之间变化。 相似文献
8.
根据大量的野外考察资料和室内测年数据,通过对全新世不同时段泥石流沉积物的分布特征研究,总结了青藏高原东缘和华北地区泥石流活动规律。认为全新世的泥石流活动与气候波动有着密切的关系,气候温暖泥石流活动强烈,气候寒冷泥石流活动减弱。近千年来频繁的人类活动加大了泥石流活动的强度和范围。 相似文献
9.
西安地区全新世气候变化与土壤侵蚀研究 总被引：1，自引：0，他引：1
为了揭示西安地区全新世环境变化和黄土地层的侵蚀期,利用野外调查和化学分析等方法,研究了西安地区全新世黄土与古土壤发育时的气候变化和不同气候阶段的土壤侵蚀。通过野外调查,在西安白鹿塬区发现了在黄土塬区很少见到全新世中期古土壤分为3个层次,整个全新世黄土剖面可分为5层,表明黄土塬区全新世气候变化与沙尘暴活动与河谷地区一样可分为5个阶段。土层氧化物、微量元素、CaCO3含量和磁化率测定结果显示,西安白鹿塬区全新世8 500~6 000年和5 000~3 100年古土壤发育时较10 000~8 500年、6 000~5 000年和3 100年以来的黄土发育时夏季风活动强,降水量多,气候湿润,沙尘暴活动弱。中全新世8 500~6 000年间发育的S02古土壤中Fe2O3和Al2O3有一定富集,该层土壤类型相当于黄棕壤,指示当时年平均降水量较现今多150 mm左右。虽然沙尘暴活动很弱的间冰期是黄土地层理论上的侵蚀期,但是实际上这一时期的土壤侵蚀很弱。全新世黄土的侵蚀主要发生在气候冷干时期,不是发生在温湿时期。全新世中期6 000~5 000年间的黄土侵蚀率一般大于堆积率,使得广大地区全新世中期的薄层黄土在绝大多数地区受到侵蚀而消失。全新世中期薄层黄土发育时气候变冷干引起的植被退化是当时土壤侵蚀加强和出现侵蚀期的原因。 相似文献
10.
泾河下游全新世古洪水滞流沉积物研究 总被引：2，自引：1，他引：2
通过对泾河流域广泛的野外考察,在泾河下游高陵县段发现了典型的全新世古洪水滞流沉积剖面,系统地进行采集样品和粒度成分、磁化率、烧失量、吸湿水含量等多指标分析。从沉积学角度将古洪水滞流沉积物与全新世风成黄土和土壤进行对比,证明了该剖面所夹古洪水滞流沉积物的性质为细砂质粉砂,属于河流洪水悬移质泥砂沉积物。根据地层结构及与流域内其它剖面的对比,结合OSL测年数据,确定泾河在全新世中期4200~4000 a B.P.发生了第1期古洪水事件,在全新世晚期3200~2800 a B.P.发生了第2期洪水事件。这些古洪水事件都发生在全球性气候突变转折时期,表明在这些时期气候极端恶化,变率增大,洪水和干旱事件皆有发生。该研究对于泾河防洪减灾、水资源开发利用,对于揭示水文系统对于全球变化的响应规律,具有重要的科学意义。 相似文献
11.
【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。 相似文献
12.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing. 相似文献
13.
《中国生态农业学报》2014,(8)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
14.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions. 相似文献
15.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils. 相似文献
16.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization
and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition
with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the
decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots
with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass,
soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration,
N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially
(<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation
in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils,
indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but
the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation
for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community
performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea. 相似文献
17.
《中国生态农业学报》2014,(7)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
18.
《中国生态农业学报》2014,(6)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
19.
Grete Skrede Berit Karoline Martinsen Anne-Berit Wold Stein-Erik Birkeland Kjersti Aaby 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):193-208
Abstract A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species. 相似文献
20.
《Communications in Soil Science and Plant Analysis》2012,43(7):865-877
Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L?1 nitric acid (HNO3) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L?1 ammonium acetate (NH4OAc) and 1.0 mol L?1 HNO3 extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils. 相似文献