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1.
基于电阻率断层扫描技术探测林地土层厚度   总被引:3,自引:1,他引:2  
土层厚度对林地生产力具有重要影响,是评价林地土壤质量的重要指标。为了对林地土壤的土层厚度进行调查,该文应用电阻率断层扫描技术对林地土壤土层厚度进行了研究,对其可适用性做出评价。通过在野外试验点对土壤电阻率的实地断层扫描,将其结果与实际测定得到的基岩特征电阻率相结合,预测土层厚度,并将预测值和实地基坑开挖数据进行比较。结果表明,研究区土层厚度多在小于2 m的范围内,电阻率断层扫描技术估测结果与实测结果相符(均方根误差为0.2678),初步表明该技术在估算林地土层厚度方面具有良好的适用性。该研究结果为土壤学方面相关研究提供重要手段,也将对土壤质量评价和土地利用等相关工作提供指导。  相似文献   

2.
土壤厚度的划分标准与案例研究   总被引:6,自引:0,他引:6  
土壤厚度一般包括土体厚度和有效土层厚度,它能直观地表达土壤性质。基于前人对于土壤厚度定义及相关厚度指标划分所做的工作,结合笔者所在课题组长期野外考察经验,从土壤发生学角度明确了土体的概念,并提出针对不同土壤类型和土地利用方式对应的土体厚度和有效土层厚度的具体划分方法。利用新提出的划分标准对近些年国内各省野外采集的16个剖面(包括安徽、湖北、山东、青海、甘肃、内蒙古等省份)进行具体厚度划分,为国内今后有关研究提供参考。  相似文献   

3.
土壤侵蚀因素对紫色丘陵区坡耕地耕层质量影响   总被引:11,自引:3,他引:8  
土壤侵蚀是导致坡耕地耕层土壤质量退化和土壤生产力不稳定的关键因素。该文以紫色丘陵区坡耕地为例,对坡耕地不同地力等级耕层土壤质量、渗透性能及耕层类型进行聚类分析,讨论了土壤侵蚀对坡耕地耕层厚度影响及合理耕层土体构型。结果表明:(1)紫色土坡耕地耕层土壤质量具有中等程度变异性,有效土层厚度(15~80 cm)和耕层厚度(15~25 cm)变异系数分别为12.18%和37.26%,土壤有效磷变异系数可达94.51%,说明土壤物理指标变异性小于化学指标变化;三级以下地力耕层构型为近似全虚或全实剖面结构,五等地力坡耕地产量下降50%左右。(2)紫色土坡耕地不同坡位、不同垂直深度的耕层土壤物理性质、持水性能及耕作性能差异显著(P0.05),土壤容重为上坡下坡中坡,土壤抗剪强度为上坡中坡下坡,土壤稳定入渗为下坡中坡上坡,土壤贯入阻力表现为中坡上坡下坡;除土壤入渗外,土壤容重、抗剪强度、贯入阻力均表现为底土层心土层耕层;坡耕地0~40 cm土层中蓄存降水可被农作物利用70%左右。(3)中度侵蚀程度坡耕地,年均耕层厚度薄化值为1.04~3.04 mm,坡耕地合理耕层建立可选择有效土层厚度、耕层厚度、土壤容重、土壤抗剪强度、土壤有机质、土壤渗透性为坡耕地合理耕层评价最小数据集,耕层构型总体保持上虚下实型、耕层厚度20~25 cm、有效土层厚度50~60 cm。(4)紫色土坡耕地可分为四种耕层类型,其障碍耕层主要表现为有效土层厚度限制型(第II类)、耕层厚度限制型(第III类)和土壤养分限制型(第IV类),分别占耕层总量30%、10%、3%;紫色土坡耕地合理耕层建立应重点关注有效土层厚度和耕层厚度调控。研究结果可为客观认识土壤侵蚀与紫色土坡耕地耕层退化关系、合理耕层构建提供理论依据和技术参数支持。  相似文献   

4.
GPR测量滨海盐渍土剖面分层的实验研究   总被引:2,自引:0,他引:2  
王萍  李新举  闵祥宇  杨东  王新  李俊颖  孙小银 《土壤》2016,48(6):1261-1269
土壤剖面分层是GPR调查研究工作的主要内容,也是时域信息提取和定量反演的基础。使用250 MHz的pulse EKKO PRO探地雷达,探测不同植被覆盖或同一植被长势差异的地块,开挖剖面实测对比GPR的分层结果,剖析电磁波信号对土壤水分、盐分、粒径组成3个因子的响应特征。结果表明,从GPR波谱特征中可以区分表层盐渍化程度不同的地块,误差多小于0.5 m;综合波谱影像和振幅变化数据,能够辨晰0~1 m的土层信息,分层误差可达0.1 m;土壤盐分对电磁波信号的影响特征在该地区表现得十分显著。  相似文献   

5.
通过土壤含水量测定,对青海湖西部天然草地不同厚度土壤含水量等问题进行了研究.结果表明,吉尔孟厚土层和薄土层土壤含水量均呈现随深度增加而逐渐降低的趋势.在相同土壤厚度条件下,低草地土壤含水量比高草地含水量高.在植被相同条件下,厚土层含水量比薄土层的含水量高.草地厚土层在80 cm深度出现土壤干层,指示当地的土壤下部水分不足.30 cm厚度的薄土层高草地和30 cm厚度的薄土层低草地分别在21和24 cm出现了含水量低于11%的干化现象.厚土层上部30 cm含水量比30 cm厚度的薄土层含水量高12.4%.吉尔孟土壤水分的突出特点是上部含水量高,说明该区土壤水分具有在上部聚集的特点,这是该区土壤冻结期较长和蒸发及蒸腾较少造成的,土壤水分在上部聚集对草原植被生长是有利的.由于该区土壤下部水分不足,该区应该发展耐旱牧草和其他耗水较少的草原植被,不适于发展深根系耗水较多的植被.  相似文献   

6.
基于GIS技术的黑龙江省典型土壤有效土层厚度调查研究   总被引:1,自引:0,他引:1  
东北典型黑土层厚度一直是诸多生态学者普遍关注的社会问题,在水利部《东北黑土区水土流失现状及潜在危险程度研究》技术框架下,通过土层厚度影响因子归类调查法,在GIS环境下建立黑龙江省典型土壤土层厚度的评估数据库,系统分析了全省典型土壤不同立地条件下的厚度量级指标,以期为相关领域研究提供科学依据。  相似文献   

7.
辽宁土壤土层厚度与抗蚀年限   总被引:4,自引:0,他引:4  
土壤的土层厚度是计算土壤慢年限重要依据。应用已有的土壤调查成果将全省的土层厚度进行分级,统计,再用遥感普查中的侵蚀模数计算出不同7层厚度之区域的抗蚀年限,为土壤侵蚀的预测预报提供重要的基础数据。  相似文献   

8.
准确掌握黑土层厚度分布信息对于黑土资源评价和保护具有重要意义。然而,传统土层厚度测定方法包括土壤剖面法、插钎法和钻孔法等对于大范围的土壤厚度测定效率较低且连续性较差。本研究利用探地雷达探测了东北黑土区直型、凸型和凹型3种坡型坡面的黑土层厚度。室内模拟试验对黑土及黄土母质土壤分别设置不同的容重和含水量,探究土壤含水量和容重对土壤介电常数的影响以及探地雷达测定黑土厚度的可行性。野外试验通过开挖剖面和预埋标识物,验证了探地雷达测量黑土厚度的准确性。结果表明:土壤介电常数随容重的增大而增大,随土壤含水量的增加而减小;黑土和黄土母质层土壤含水量、容重和介电常数之间的关系可以用两个对数方程来描述,其精确度为95.26%~99.66%。探地雷达测量黑土厚度与剖面实测厚度相比,精确度为87.05%~95.58%。3个坡面的黑土厚度空间分布不同,且坡脚发生沉积处的黑土厚度较大,坡肩和坡背土壤侵蚀较严重处的黑土厚度较薄。本研究可为进一步探明和保护黑土资源提供一种高效、准确的土壤厚度调查方法。  相似文献   

9.
东北黑土区是中国重要的粮食生产基地,自开垦以来,土壤生产力退化严重。探索简易可行的黑土生产力评价方法,可为合理利用和保护黑土资源提供科学依据。以位于典型黑土区北端的鹤北小流域为例,基于黑土厚度和土壤理化性质的野外调查,构建了用黑土层厚度评价土壤生产力的方法。结果表明,黑土层厚度与土壤生产力水平间呈对数关系,当黑土厚度小于40-50 cm时,随着厚度增加,土壤生产力增加明显;当黑土厚度大于40-50 cm时,随厚度增加土壤生产力增加速度减缓。多年大豆单产及当地土地分等定级的双重验证表明用黑土层厚度评价土壤生产力简易可行,能够揭示土壤生产力的空间分异。研究区耕作方式对土壤生产力影响显著:同一地块内从坡顶到坡脚生产力呈增加趋势,但在等高种植情况下,地块土壤生产力差异较小,顺坡或与等高线交叉情况下,地块土壤生产力差异较大。  相似文献   

10.
基于探地雷达的滨海盐渍土表层含水量测定研究   总被引:1,自引:1,他引:0  
《土壤通报》2017,(6):1329-1337
本研究选取了17个植被类型不同或长势不同的典型地块,利用250 MHz中心频率探地雷达,采用固定间距法和共中心点法两种测量方法,分析电磁波信号对土壤剖面特性变异分层的响应特征,提取地面波和表层反射波的传播速度,代入常用的11个土壤介电常数—含水量经验模型,反演表层土壤(0~30 cm)体积含水量。GPR图像可清晰识别0~1m土层的空气波、地面波和反射波信号;GPR反演体积含水量与农田表层土壤实测质量含水量的相关系数可达0.8以上,其中以Topp模型与巨兆强模型的相关系数最高,朱安宁粉砂黏潮土的θ~ε经验模型的平均反演误差为0.012 m~3 m~(-3);对于表层土壤盐分较高的地块,反射波信号反演表层土壤含水量的效果优于地面波;表层土壤扰动越大,雷达波信号提取误差越大,GPR反演含水量的精确度越低。  相似文献   

11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响   总被引:2,自引:2,他引:0  
【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.
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.
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.
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   

15.
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   

16.
Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.  相似文献   

17.
李聃枫  朱春梧 《土壤》2020,52(3):561-566
自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。  相似文献   

18.
Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.  相似文献   

19.
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.
“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.  相似文献   

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