The effect of soil texture and organic amendment on the hydrological behaviour of coarse-textured soils     

J. G. Wesseling    C. R. Stoof    C. J. Ritsema    K. Oostindie  & L. W. Dekker 《Soil Use and Management》2009,25(3):274-283

To gain more insight into the hydrological behaviour of coarse-textured soils, the physical properties of artificially created soil mixtures with different texture were determined. The mixtures were prepared according to the specifications of the United States Golf Association (USGA) for constructing putting greens. In addition, the effect of 10 vol.% organic matter addition was studied. The soil moisture retention and hydraulic conductivity relationships of the different mixtures were determined and their hydrological behaviour was studied using the numerical model SoWaM. Both texture and organic matter addition substantially affected the hydraulic properties. Hydraulic conductivity significantly increased with increasing coarseness while moisture retention decreased. On the other hand, organic matter addition reduced saturated hydraulic conductivity by a factor of 10 to 100 and distinctly increased moisture retention capacity. The amounts of total available water were increased by the addition of organic matter between 144% (slightly coarse texture) and 434% (very coarse texture). Results indicate that the mixtures can contain only 2–16% plant available water and therefore need frequent irrigation to maintain plant growth. Addition of organic matter seems a good solution to reduce the irrigation water requirements but it increases the risk of ponding or runoff because of large reductions in the saturated hydraulic conductivity sometimes to below the rate of 3.6 m/day recommended by the USGA.  相似文献   

Transect relascope sampling for assessing coarse woody debris: The case of a π/2 relascope angle     

《Scandinavian Journal of Forest Research》2012,27(4):375-381

In transect relascope sampling, a wide‐angle relascope is used along survey lines for selecting a sample of objects that extend linearly in the plane, e.g. downed logs. The method is closely related to line intersect (intercept) sampling. In this article, a special case of the transect relascope technique is studied. Using a π/2 radian relascope angle, the method becomes invariant to the orientation of the line objects in the population. The reason is that the area of inclusion around objects, through which a survey line should pass for an object to be included, turns out to be circular. In analytical studies and Monte Carlo simulations, the cost‐efficiency of transect relascope and line intersect sampling is evaluated. It is found that transect relascope sampling is a competitive alternative to line intersect sampling in inventories of the total volume of coarse woody debris (in the form of downed logs) in forest compartments.  相似文献   

Epiphytic life is the main characteristic of the life cycle ofPseudomonas syringae pv.pisi,pea bacterial blight agent     

Catherine Grondeau  Alexandre Mabiala  Rachid Ait-Oumeziane  Régine Samson 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(4):353-363

Pseudomonas syringae pv.pisi, pea bacterial blight agent, is seed-transmitted. Some aspects of its life cycle and its biology were investigated. The colonization of pea plants obtained from naturally infected seeds was studied in natural conditions while high populations of bacteria developed on plants showing no symptoms. Two streptomycin-resistant mutants were used to study the epiphytic life of the pathogen. Populations were monitored in different host-parasite compatibilities. When race 2 or race 6 of the pathogen was surface-inoculated on susceptible cultivars, a decrease of population size was observed during the following one to three days but was followed by an increase to levels 1000 times greater than the initial number detected, without symptoms for most of the plants. When race 2 was surface-inoculated on resistant genotypes or race 6 on non-host plants, bacteria did not multiply but population levels slightly decreased.Pseudomonas syringae pv.pisi shows a resident phase and its development is race-specific. Weeds collected in naturally contaminated pea fields, diseased or not, often harboured the pathogen but with levels smaller than those observed on peas. Pea crop debris and volunteers kept high levels of bacteria for at least eight months after the harvest of a diseased crop. As long as two pea crops are not grown one after the other in the same field, it is unlikely that debris and volunteers will act as an important inoculum source. The development of this pathogen during the growing season is considered as an important parameter to take into account for controlling the disease through seed health testing.  相似文献   

Extinction risk of wood-living model species in forest landscapes as related to forest history and conservation strategy     

Thomas Ranius  Oskar Kindvall 《Landscape Ecology》2006,21(5):687-698

Dead wood is a critical resource for biodiversity in boreal forests. We analysed the persistence of five model species inhabiting dead wood. By parameterising a metapopulation model (the incidence function model), the model species were all assigned characteristics that makes it likely that they have disappeared from some (20%) forest landscapes with a long history of forest management. In the metapopulation model, a forest stand (5 ha) was regarded as a habitat patch. The amount of habitat in each patch was obtained from models of dead wood dynamics of Norway spruce in central Sweden. Dead wood generated by altered management over the entire landscape was found to be less efficient in reducing extinction risks in comparison to the same amount of dead wood generated by protecting reserves. Because generation of dead wood by altered management is often less expensive than setting aside reserves, it is difficult to determine which conservation measure is most cost-efficient. In a landscape subjected to forestry for the first time, it was better to preserve a few large reserves than many small ones. However, in a managed, highly fragmented forest landscape it was better to set aside many small reserves. The reason for this was that small plots with high habitat quality could be selected, while large reserves originally contained habitats both of high and low quality, and the rate of habitat quality increase was low. A strategy for biodiversity conservation in a managed forest landscape should include information about the history of the landscape, the current amount and spatial distribution of forest habitats, and the potential for rapid restoration of forest habitats, both on managed and unmanaged forest land.  相似文献   

Effects of grazing strategy on limiting nitrate leaching in grazed grass‐clover pastures on coarse sandy soil     

E. M. Hansen  J. Eriksen  K. Søegaard  K. Kristensen 《Soil Use and Management》2012,28(4):478-487

Urinations of ruminants on grazed pastures increase the risk of nitrate leaching. The study investigated the effect of reducing the length of the grazing season on nitrate leaching from a coarse sandy, irrigated soil during 2006–2007 and 2007–2008. In both years, precipitation was above the long‐term mean. The experiment was initiated in a 4‐yr‐old grass‐clover sward in south Denmark. Three treatments were as follows grazing only (G), spring cut followed by grazing (CG) and both spring and autumn cuts with summer grazing (CGC). Nitrate leaching was calculated by extracting water isolates from 80 cm depth using ceramic suction cups. Because of considerable variation in measured nitrate concentrations, the 32 installed suction cups per treatment were insufficient to reveal differences between treatments. However, weighted nitrate leaching estimations for G, CG and CGC showed estimated mean nitrate N concentrations of 23, 19 and 13 mg/L for an estimated proportion area occupied by urine patches of 0.33, 0.26 and 0.16, respectively. Thus, N concentrations in G and CG exceeded the EU limit of 11.3 mg N/L. Under the prevailing conditions, the time of urination did not appear important. The estimated background leaching calculated from suction cups presumably not situated under urine patches resulted in mean nitrate N concentrations of 2.6 mg/L.  相似文献   

金平县林产业发展探讨     

吴宁 《林业调查规划》2009,34(1):112-115

金平县2007年林业产值为1．91亿元，占全县农业总产值的35％，是林业重点县．该县具有发展林产业的优势项目，包括橡胶种植业、竹藤产业、木本油料（油荼）业、核桃特色经济林产业、杉木珍贵用材林产业以及草果林下资源开发等．分析了林产业发展的有利和不利因素．进行了产业发展规划和布局．提出加快集体林权制度改革、加大资金投入、加强科技支撑、扶持龙头企业、组建专业合作组织等保障措施．  相似文献   

浙江武义县木本植物资源的开发利用     

刘鹏  陈立人 《浙江林业科技》1996,16(3):58-63

浙江武义县木本植物资源丰富，计有９２科２６８属６８０种，论述了这些资源植物的基本特点后，按其经济性状，将其分为材用、果类、纤维、油脂、芳香、鞣料、观赏、密源、药用、淀粉共１０类，最后对它们的综合利用提了一些建议，将为今后的开发利用提供依据。  相似文献   

地带性木本植物群落功能型的水热分布格局     

王国宏 《林业科学》2002,38(1)

植物功能型是对环境条件做出相似的反应和对关键生态学过程具有相似影响的植物组合.不同功能型植物对生态系统过程的作用不同,通过植物功能型的分析对揭示生态系统功能至关重要.甘肃省境内5种地带性木本植物群落(亚热带常绿落叶阔叶林、暖温带落叶阔叶林、温带针阔混交林、寒温性针叶林和荒漠旱生灌木群落)依据植物体的高度、叶片的生长对策及果实类型可划分出23种功能型.其分布格局与水热因子的相关分析表明:1)湿热的生境利于乔木、大灌木、藤木、寄生植物和常绿植物及翅果、坚果、核果、NFDA5NFDA6果、颖果类植物的发育,干冷生境利于灌木、小灌木和落叶植物以及蒴果类植物的发育.2)干果类和肉果类的成因可能与植物生长环境中水分供应状况密切相关,即潮湿的生境利于肉果类植物的发育,干旱的生境有利于干果类(如胞果)的发育.3)研究区域地带性木本植物群落物种丰富度和功能型的丰富度格局主要受制于水分梯度影响,而良好的水热组合可孕育木本植物群落最丰富的果实类型.  相似文献   

Effect of pruning intensities of three woody leguminous species grown in alley cropping with maize and cowpea on an alfisol     

B. Duguma  B. T. Kang  D. U. U. Okali 《Agroforestry Systems》1988,6(1-3):19-35

Field trials were carried out on an Oxic Paleustalf in the humid zone of southwestern Nigeria withLeucaena leucocephala (Lam.) de Wit,Gliricidia sepium (Jacq.) Steud. andSesbania grandiflora (L.) Pers. alley cropped with maize and cowpea. The three leguminous woody species were grown in hedgerows spaced at 2 m. Trials were carried out one year after establishment of the hedgerows using a split-plot design with four replications. TheLeucaena trial had twenty pruning combinations consisting of five pruning heights (25, 50, 75, 100 and 150 cm) and four pruning frequencies (monthly, bi-, tri- and six-monthly). TheGliricidia andSesbania hedgerows were subjected to nine pruning intensities consisting of three pruning heights (25, 50 and 100 cm) and three pruning intensities (monthly, tri- and six-monthly). For the three woody species, biomass, dry wood and nitrogen yield from the hedgerow prunings increased with decreasing pruning frequency and increasing pruning height. Biomass, dry wood and nitrogen yields were in the following orderLeucaena >Gliricidia >Sesbania. The various pruning intensities had no effect on survival ofLeucaena plants. Pruning frequency had a larger effect than pruning height on survival ofGliricidia andSesbania plants. With monthly pruning, about 25 percent of theGliricidia and all of theSesbania plants died within six months of repeated pruning. Even with lower pruning frequencySesbania plants showed lower survival rates thanGliricidia orLeucaena. The various pruning intensities of all the hedgerow species had more pronounced effects on the grain yield of the alley cropped cowpea than on maize grain yield. Higher maize and cowpea yields were obtained with increasing pruning frequency and decreasing pruning height. IITA Journal paper number 335  相似文献   

彩叶木本植物育种研究进展   总被引：5，自引：0，他引：5  

高立旦  童再康  曹件生  黄华宏 《浙江林业科技》2006,26(4):77-82

列出了106种常见的彩叶木本植物，综述了彩叶木本植物的育种和良种繁育技术研究状况，并分析了其在园林建设中的应用和发展前景。  相似文献