Assessing the effects of initial soil characteristics,machine mass and traffic intensity on forest soil compaction   总被引：1，自引：0，他引：1  

E. Ampoorter  L. Van Nevel  B. De Vos  M. Hermy  K. Verheyen 《Forest Ecology and Management》2010

An extensive field trial was set up in eight forest stands to examine the influence of soil texture (two stands on sand, four on loam to silt loam, two on clay), machine mass (light, heavy) and traffic intensity (one and five skidding cycles) (i.e. pass back and forth on the skid trail) on soil compaction after mechanized harvesting. Dry bulk density (BD), penetration resistance (PR), micro-topography and soil carbon dioxide (CO₂) concentration were applied as response variables for soil compaction. Significant effects on BD were nearly absent (<7% increase) and occurred occasionally for PR (60–70% increase, up to 150% on clay soils). Especially for loam to silt loam and clay soils, this was in contrast with the expectation. The negligible compaction degrees for loam to silt loam are attributed to high initial compaction levels that prevented further compaction, as was found by general linear modelling (GLM) for both BD and PR. For clay soils the small compaction degrees can be explained by the high water contents that result in plastic deformation instead of strong compaction degrees, as was confirmed by the micro-topographical measurements. GLM also revealed a significant impact of machine mass (BD) and soil water content (BD, PR) on the compaction degree. Soil texture, traffic intensity and position in relation to the wheel tracks generally turned out to have an insignificant influence. With regard to clear interactions the influence of traffic intensity depends on the position in relation to the wheel tracks and the machine that was used (PR).  相似文献   

不同坐果期枣果实品质差异的研究     

王德  高疆生  吴翠云  王艳  王志强  孙亚强 《新疆农业科学》2016,53(2):254

[目的]比较不同坐果期枣果实品质的差异,为提高枣的精细化管理水平提供科学依据.[方法]挂牌标记枣树的头蓬果、二蓬果、三蓬果,于果实脆熟期末采收.分别测定枣果实物理性状(单果重、果形指数、可食率、含水量、干物质量)和果实内含物含量(可溶性糖、还原糖、淀粉、VC、有机酸、蛋白质),采用TMS-Pro质构仪测定果实质地参数,并进行比较分析.[结果]枣头蓬果、二蓬果、三蓬果的大小、形状和可食部分干物质量均存在显著差异,并依次减小;二蓬果的VC、可溶性蛋白质、可溶性糖、有机酸、淀粉和还原糖含量均高于头蓬果、三蓬果的含量;供试材料不同坐果期枣果实质地各参数间也存在差异.[结论]不同坐果期枣果实品质存在较大差异,头蓬果和二蓬果品质优于三蓬果,采用疏果等措施可提高枣的商品性和经济效益.  相似文献   

融合海肾荧光素酶的重组病毒在移码和通读研究中的应用初探     

于成明  王国鲁  王德亚  师科荣  原雪峰 《植物病理学报》2016,46(6):846-849

<正>海肾荧光素酶(Renilla Luciferase,Rluc)可催化腔肠素(coelenterazine)氧化产生高能量中间产物,氧化过程同时发出蓝色生物荧光,最强荧光波长465 nm。鉴于荧光素酶生物发光的高灵敏度检测特性,由海肾荧光素酶和另一种萤火虫荧光素酶(Firefly Luciferase,Fluc)组成的单报告和双报告基因检测系统广泛应用于生命科学研究领域,如遗传毒性检测、信号通路研究和某些顺式作用元件的  相似文献   

Evolution and distribution of virulence characteristics of Belgian Bremia lactucae populations between 2008 and 2013     

Nathalie Van Hese  Chien-Jui Huang  David De Vleesschauwer  Ilse Delaere  Ellen Pauwelyn  Peter Bleyaert  Monica Höfte 《European journal of plant pathology / European Foundation for Plant Pathology》2016,144(2):431-441

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Inter-laboratory comparison of four RT-PCR based methods for the generic detection of pospiviroids in tomato leaves and seeds     

Thibaut Olivier  Vaidevutis Šveikauskas  Elisabeth Demonty  Kris De Jonghe  Pascal Gentit  Mojca Viršček-Marn  Sabine Grausgruber-Gröger  Sébastien Morio  Francesco Faggioli  Michèle Visage  Frédéric Fauche  Maria Gusina  Marta Luigi  Helena Lasner  Irena Mavrič-Pleško 《European journal of plant pathology / European Foundation for Plant Pathology》2016,144(3):645-654

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Genetic structuring among populations of the great egret,Ardea alba egretta,in major Brazilian wetlands          下载免费PDF全文

Thaís Camilo Corrêa  Silvia Nassif Del Lama  Juliana Rossi De Souza  Carolina Isabel Miño 《水产资源保护:海洋与淡水生态系统》2016,26(2):333-349

Microalgal bacterial flocs originating from aquaculture wastewater treatment as diet ingredient for Litopenaeus vannamei (Boone)          下载免费PDF全文

Sofie Van Den Hende  Leon Claessens  Eric De Muylder  Han Vervaeren 《Aquaculture Research》2016,47(4):1075-1089

Microalgal bacterial flocs (MaB‐flocs) in sequencing batch reactors are a novel and promising technology to treat aquaculture wastewater. To improve the economics of this technology, the harvested MaB‐flocs should be valorized. Therefore, we investigated if MaB‐flocs from an outdoor pilot reactor treating pikeperch (Sander lucioperca L.) wastewater can be used as a colour enhancing ingredient for shrimp diets. Considering the nutritional composition and high ash content of MaB‐flocs, five iso‐nitrogenous and iso‐lipidic shrimp diets were formulated by replacing 2–8% of the basal diet ingredients by MaB‐flocs. These diets were continuously fed to juvenile Pacific white shrimps Litopenaeus vannamei (Boone) cultured in a hybrid recirculating aquaculture system. The addition of these relatively low amounts of MaB‐flocs to shrimp diets significantly increased the pigmentation (redness and yellowness) of cooked shrimp tails. The diet modifications did not affect the shrimp survival, weight gain, size distribution and food conversion rate, nor did they affect the proximate composition and fatty acid profile of the raw shrimp muscle. This shows that MaB‐flocs originating from treatment of pikeperch wastewater can substitute 8% of diet ingredients of Pacific white shrimp while enhancing its pigmentation.  相似文献   

Is risk consistent across tier‐based harvest control rule management systems? A comparison of four case‐studies          下载免费PDF全文

Catherine M Dichmont  André E Punt  Natalie Dowling  José A A De Oliveira  Lorne R Little  Miriana Sporcic  Elizabeth Fulton  Rebecca Gorton  Neil Klaer  Malcolm Haddon  David C Smith 《Fish and Fisheries》2016,17(3):731-747

There can be substantial differences in data quality and quantity among fished species. Consequently, the quality and type of assessments can also vary substantially. However, all species, especially those that are targeted, need to be managed. Several jurisdictions have developed hierarchical tier systems that categorize stocks based on, for example, the data available for assessment purposes and/or the extent to which quantities on which management advice is based can be estimated. Four case‐studies (Australia's Southern and Eastern Scalefish and Shark Fishery, the USA west coast groundfishery, the USA Alaskan crab fishery and EU fisheries) are used to contrast the types of hierarchical tier systems available, and to assess the extent to which each system constrains risk to be equivalent among the tiers (termed risk equivalency). Only the Australian system explicitly aims to achieve risk equivalency. However, this intent has not been fully operationalized. Our review reveals that best practice is not to define tiers simply on data availability, but also on what the assessments based on those data are capable of estimating. In addition, clearly differentiating the quantification of uncertainty from how decision‐makers wish to address that uncertainty would simplify justification of buffers (the gap between the assessment‐produced target catch or effort and the final management decision that accounts for uncertainty and risk). Risk equivalency can be achieved using management strategy evaluation to select the values for control variables, which determine the buffer given the uncertainty associated with the assessment.  相似文献   

分蘖期水稻地上部和空气间的NO_X (NO,NO₂ ) 交换作用     

徐胜光  陈能场  周建民  吴启堂  毕德 《植物营养与肥料学报》2009,15(6):1357-1363

采用密闭箱法结合42 C型 NO-NO2-NOX 分析仪的快速线检测系统,在气候箱严密控光（L1）和室内自然光暗处理（L2）条件下,研究了分蘖期水稻地上部和空气间的NOX（NO, NO2 ）交换作用,结果表明: 1）试验用水稻品种具有较强的NO挥发能力,在L1、L2条件下水稻NO平均挥发速率 [按鲜质量（g, FW）计算] 分别达到0.0188、0.0239 g/（g·h）,并在环境空气NO浓度达100 g/m3条件下水稻也能净排放NO;2）水稻能吸收空气NO2,L1、L2条件下水稻NO2平均净吸收速率为0.00084、0.00165 g/（g·h）;3）施氮能增强水稻NO挥发,在气候箱严密控光（L1）条件下,短期内（1～2 d）施氮在日间 6:00～10:00 弱光时段和 10:00～14:00强光时段有刺激水稻NOX （NO, NO2 ）挥发的效应, 但在14:00～18:00 时段,持续强光能削弱施氮对水稻NO挥发的刺激作用而增强水稻对NO2吸收。4）室内自然弱光条件下（L2）,施氮能提高日间水稻的NO净挥发速率,水稻NO2净吸收速率随着有光时间的延长而上升。夜间暗处理条件下,施氮对促进水稻NO的挥发无明显作用,水稻NO2吸收速率下降。试验结果显示,水稻地上部从空气中净吸收NO2的平均速率远低于NO净挥发速率,分蘖期水稻地上部分与空气间的NOX （NO, NO2 ）交换作用主要表现为NO的净挥发,相当于净损失纯N 10.95～12.5 g/（hm2 ·d）。  相似文献   

Ordinal regression models for predicting deoxynivalenol in winter wheat     

S. Landschoot  W. Waegeman  K. Audenaert  G. Haesaert  B. De Baets 《Plant pathology》2013,62(6):1319-1329

Deoxynivalenol (DON) is one of the most prevalent toxins in Fusarium‐infected wheat samples. Accurate forecasting systems that predict the presence of DON are useful to underpin decision making on the application of fungicides, to identify fields under risk, and to help minimize the risk of food and feed contamination with DON. To this end, existing forecasting systems often adopt statistical regression models, in which attempts are made to predict DON values as a continuous variable. In contrast, this paper advocates the use of ordinal regression models for the prediction of DON values, by defining thresholds for converting continuous DON values into a fixed number of well‐chosen risk classes. Objective criteria for selecting these thresholds in a meaningful way are proposed. The resulting approach was evaluated on a sizeable field experiment in Belgium, for which measurements of DON values and various types of predictor variables were collected at 18 locations during 2002–2011. The results demonstrate that modelling and evaluating DON values on an ordinal scale leads to a more accurate and more easily interpreted predictive performance. Compared to traditional regression models, an improvement could be observed for support vector ordinal regression models and proportional odds models.  相似文献