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Dr. F. Kühlhorn 《Journal of pest science》1983,56(6):109-113
A survey of the most important enemies of Diptera found out in stables of useful beasts is given. These are: disease fungus (Mycophyta), mites (Acari), spiders (Araneae), parasitic and predacious wasps (Hymenoptera), staphlinids (Coleoptera), larvae and adults of Diptera as well as birds of certain species. At voland species of enemies it will reported about the behaviour of the flight indoors and outdoors, the behaviour in the stable room and that of the enemies against their prey of Diptera by predators. 相似文献
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B. G. Lockaby R. G. Clawson K. Flynn R. Rummer S. Meadows B. Stokes J. Stanturf 《Forest Ecology and Management》1997,90(2-3):187-194
Floodplain forests contribute to the maintenance of water quality as a result of various biogeochemical transformations which occur within them. In particular, they can serve as sinks for nutrient run-off from adjacent uplands or as nutrient transformers as water moves downstream. However, little is known about the potential that land management activities may have for alteration of these biogeochemical functions. This paper examines the effects of three harvesting regimes (unharvested control, clearcut, and partial cut) on the physical and chemical parameters within the Flint River floodplain located in southwestern Georgia, USA. Data presented in this paper were collected during the year following initiation of the harvesting treatments which occurred in September of 1993. Sheetflow water chemistry (total suspended solids (TSS), total dissolved solids (TDS), nitrate (NO3−), phosphate (PO43−), sulfate (SO42−), calcium (Ca2+), potassium (K+), magnesium (Mg2+), ammonium (NH4+), total phosphorous (P), total nitrogen (N), total carbon (C), dissolved organic carbon (DOC)), sedimentation rates, depth of soil oxidation after flooding, saturated hydraulic conductivity, and bulk density were measured. During the year immediately after treatment installation, alterations in some of the physical and chemical properties (TDS, NO3−, total P, and K+) of floodwaters crossing harvest plots were detected. Soil oxidation depths, saturated hydraulic conductivity and bulk density also changed with treatment. The meaning of the changes detected is uncertain but they suggest the nature of potential changes in nutrient spiralling and non-point source cumulative effects that may occur within a managed watershed. Second-year data may offer an interesting comparison of sheetflow chemistry and sedimentation changes between vegetated and non-vegetated conditions. 相似文献
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通过对25种玉簪属植物在哈尔滨地区的引种观察,研究其生长发育规律及引种适应性。结果表明,筛选出的Hosta undulate‘Mediovariegata’(40号)、Hosta‘Royal Standayd’(24号)、Hosta‘One man’s Treasure’(21号)、Hosta tardiana Hort.‘Halcyon’(37号)、Hosta‘Christmas Tree’(6号)、Hosta‘Shade Fanfare’(26号)和Hosta fortune(Baker.)Bailey‘Aureomarginata’(35号)等7种优良玉簪属植物品种抗寒能力强、生长发育正常、观赏效果良好、无病虫感染,适合哈尔滨地区环境条件,可以在哈尔滨地区大量引种栽培建圃扩繁或用作园林绿化。 相似文献
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为了解云南蒋家沟流域土壤种子库在不同海拔梯度上的变化特征,明确种子库对植被垂直带谱的响应性机制及群落恢复潜力,选取蒋家沟流域8条海拔带[Ⅰ(2700~2900 m)、Ⅱ(2500~2700 m)、Ⅲ(2300~2500 m)、Ⅳ(2100~2300 m)、Ⅴ(1900~2100 m)、Ⅵ(1700~1900 m)、Ⅶ(1500~1700 m)、Ⅷ(1300~1500 m)]为研究对象,对其植物群落土壤种子库的数量特征、物种组成、物种多样性及种子库相似性进行研究。结果表明:Ⅲ、Ⅱ海拔带的平均物种数和种子密度显著高于Ⅶ、Ⅷ海拔带,土壤种子库种子密度与物种数量随海拔降低而逐渐减少;Ⅰ、Ⅱ、Ⅲ海拔带的Margalef丰富度指数(M)大于5.000,Ⅶ、Ⅷ海拔带M小于3.000。种子库萌发物种以菊科和禾本科草本植物为主,海拔2300 m以上以多年生草本植物占优势,海拔2100 m以下则以1年和2年生草本植物占优势。各海拔带物种分布均匀性较好,除Ⅵ海拔带外,其余海拔带Pielou均匀度指数(J)均大于0.900。Ⅲ海拔带的Simpson优势度指数(D)和Shannon-Wiener多样性指数(H)最高,分别为0.942和3.006;Ⅶ海拔带的D和H最低,为0.810和1.720。除Ⅶ、Ⅷ海拔带以外,其余海拔带的土壤种子库均与临近海拔带种子库相似性最高,Sorensen相似性系数(CS)为0.400≤CS<0.550,且整体上表现为随海拔升高CS逐渐减小的趋势。蒋家沟流域植被群落土壤种子库的变化受海拔梯度的影响,与蒋家沟流域内气候的垂直地带分布具有一定的关系。 相似文献
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日光节能温室内种植的矮甜李选择授粉方法是获得高产的关键。通过人工点授、自然授粉、室内放蜂、液体授粉 4种方法的对比 ,总结出 4种授粉方法的坐果率为人工点授 (3 1 .0 7% ) >室内放蜂 (2 1 % ) >液体授粉 (9.5 3 % ) >自然授粉 (0 .1 6% ) ,从试验结果看出 ,保护地种植矮甜李必须进行辅助授粉 ,否则无产量。从经济、快捷、简便的角度出发 ,以室内放蜂为最佳授粉方法 ,放蜂量为 1 0 0 0头 /棚。 相似文献
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Distribution of cranes in Hulunber Grassland and Daxing'an Mountains Forest Region in Inner Mongolia
lntroductionAnimaIResearchlnstituteoftheChineseAcademyofSciences.ForestProgramInstituteofDaxing'anMountain,InnerMongoliaUniversity,lnnerMongoIiaFarmingandAnimalHusbandryCoIlege,NortheastForestryUniversity,etc.haveconductedaseriesofinvestigationandstudiesonthefauna,popuIationofeconomic-valuedspeciesandmousepestcontrolinlnnerMongoIianD..i.gi..MountainsForestsandHulunberGrassIand.AfewmonographsandpapersonitwerepubIished.Butspecificstudiesandthor-Oughinvestigationhavenotbeendoneoncran… 相似文献
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湛江市区土地景观格局动态变化分析 总被引：2，自引：0，他引：2
利用遥感影像和地理信息系统技术,分析了湛江市区1991年、2000年和2007年3个时期土地景观格局的总体变化情况,结果表明,湛江市区具有景观破碎化程度先提高后降低,景观结构组成复杂化趋势先快后慢,城市发展影响了景观格局变化等特点。在类型水平上选择了景观类型面积(CA)、斑块数目(NP)、类型百分比(PLAND)、斑块密度(PD)、平均斑块面积(AREA-MN)共5个景观指数;在景观水平上选择了景观类型总面积(TA)、斑块数目、斑块密度、最大斑块指数(LPI)、平均斑块面积(AREA-MN)、香农多样性指数(即SHDI,为各斑块类别丰富度总和的负值)共6个景观指数。这些景观指数表明:近20 a来,湛江市区土地景观格局变化幅度大,人类活动对城市景观要素和整个景观格局的影响很深远。并进一步讨论该区景观格局动态变化的驱动力,提出了相应的对策。 相似文献
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Andrzej Węgiel Stanisław Małek Ernest Bielinis Donald L. Grebner Krzysztof Polowy Joanna Skonieczna 《Scandinavian Journal of Forest Research》2018,33(3):261-270
Increasing demand for renewable energy and limiting CO2 emissions have stimulated much interest in wood-based biofuels. Unfortunately, expanding the utilization of forest biomass may cause nutrient depletion in forested environments. This study investigates the element content from various parts of the tree. Comparisons were made between different harvesting scenarios and their impact on the amount of nutrients removed from the forest environment. The harvesting scenarios were: stem-only harvesting (SOH), branch and stem harvesting (BSH), and two variants of whole-tree harvesting (WTH). The elements taken into account were: carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), sulphur (S), copper (Cu), iron (Fe), nickel (Ni), manganese (Mn), zinc (Zn), cadmium (Cd), chromium (Cr) and lead (Pb). To make the results comparable, the same amount of removed biomass was taken into calculation. The differences between harvesting scenarios were significant. The amounts of removed elements formed similar pattern: the lowest level was found in SOH, average in BSH, and highest in both variants of WTH. This confirms that the application of WTH is connected with increased risk of nutrient depletion, even when the volume of harvest would be equal to other variants. 相似文献
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微波辅助萃取-固相微萃取联用技术分析桑叶挥发性成分 总被引：3，自引：0，他引：3
用微波辅助萃取-固相微萃取联用技术,结合气相色谱-质谱法对桑叶挥发性成分进行了鉴定,并用面积归一化法测定其相对含量.共鉴定出化合物45种,包括酮、醇、酸、烷烃、烯烃、甾醇、醛、酯及杂环化合物等,其中酮类化合物占总色谱馏出峰面积的 6.56%;醇类化合物占 33.32%;酸类占 13.71%;烃类占 23.44%.主要化合物有: 3,7,11,15-四甲基-2-十六醇(24.05%)、1-乙酰基-4-异丙基-二环[3.1.0]己烷 (16.27%)、5-(2-异丁烯基)-4,6,6-三甲基-3-环己烯酸(8.35%)、3,7,11,15-四甲基-2-十六碳烯-1-醇(5.67%).该技术可以简便、快捷、准确地进行桑叶挥发性成分的分析鉴定. 相似文献
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湘潭锰矿矿渣废弃地植被修复盆栽试验 总被引：3，自引：2，他引：3
通过分析湘潭锰矿矿渣废弃地土壤理化性质和重金属元素含量,采用矿渣废弃地土壤进行盆栽试验.结果表明:湘潭锰矿矿渣废弃地土壤质地为粗砂土类,土壤自然含水量与邻近非矿区杉木林对照地的差异显著,而土壤容重和土壤总孔隙度与邻近非矿区杉木林对照地的差异均不显著;矿渣废弃地土壤的pH值平均为7.49,P和Ca的平均含量分别为1.01、4.41 g/kg,都显著高于邻近非矿区杉木林对照地,而N含量显著低于邻近非矿区杉木林对照地,土壤有机质、K和Mg含量与邻近非矿区杉木林对照地差异不显著;矿渣废弃地土壤中的Mn、Cu、Cd、Ni、Zn、Pb平均含量分别是邻近非矿区杉木林对照地的18.59、1.32、4.10、4.66、4.44和3.16倍;与湖南省土壤重金属元素背景值、全国土壤重金属元素平均值相比较,湘潭锰矿矿渣废弃地土壤重金属元素Mn、Cu、Pb、Zn、Cd、Ni的含量都明显偏高,特别是Cd含量,分别高出104.24倍和135.40倍;栾树对矿渣废弃地土壤基质适应性强,生势旺盛,是矿渣废弃地生态恢复的首选植物,千头柏可作为矿渣废弃地生态恢复的次选植物,棕榈可适当发展,洒金柏不能作为矿渣废弃地生态恢复的植物. 相似文献
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对山西省木本攀援植物进行了详细清查,初步摸清共有70种(包括7个变种),隶属26属18科。根据攀援习性划分为缠绕类28种、卷攀类29种、吸附类6种、棘刺类7种,从开发利用方向上划分为园林型28种、果用型32种、药用型39种、生态抗逆型9种,并对其开发利用进行了简要介绍。 相似文献
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《Journal of Sustainable Forestry》2013,32(1):19-36
Abstract Persistent deforestation is one of the major constraints to sustainable economic development in Nigeria. This study used the Error Correction Mechanism (ECM) to determine the economic factors influencing deforestation. The data were national aggregates collected from several secondary sources for 1961-2000. Data analysis showed that there were at least 7 cointegrating vectors in the estimated model. Also, the dynamic unrestricted short-run parameters of cereal cropland growth rates (0.564), tuber cropland growth rates (-1.961), permanent cropland growth rate (22.136), tuber yield (0.126), livestock population (-2.156), human population (-9.214), other land areas (0.281), agricultural Gross Domestic Product (0.156), and roundwood production (0.684) had significant impact on deforestation (p < 0.05). The study recommends that efforts to address further deforestation should include enforcement of laws guiding the cutting of forest trees and research development to ensure development of crop hybrids that are resistant to environmental Stress, among others. 相似文献
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福建不同产地麻竹光合性状研究 总被引：4，自引：0，他引：4
通过对福建省 7个不同产地麻竹生长初期的叶绿素含量及叶片净光合速率 (Pn)、气孔导度 (Cs)、胞间 CO2 浓度 (Ci)、气孔阻力 (Rs)及气孔导量 (COND)等 6个性状的研究 ,结果表明 :叶绿素含量为 1 a<2 a,不同产地变化趋势为南带 >中带 >北带 ;晴天条件下 ,不同产地麻竹净光合速率日变化呈现双峰曲线 ,“午休”现象明显 ,南带产地南靖、北带产地飞鸾表现较好。细胞间 CO2 浓度与麻竹光合作用关系最为密切 ,相关系数为 - 0 .932 2 ;不同产地的净光合速率与光合性状之间存在着相互促进和相互制约的关系 ,它们直接或间接影响到竹林的生长。 相似文献
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WAHYUNI Tien 《中国林业科技(英文版)》2005,4(1):67-73
1 INTRODUCTIONDevelopment of urban area is often expressed byexistence of growth of city physical, which is moredetermined by existing facilities and basic facilities.Development of urban area indicates tendency for theminimization of green air space as well as eliminatingnatural cover. Many land functions have been changedto become shops, settlements, recreation places,industrial and others.With growing of ability and prosperity of society,development of urban area continues to accelerat… 相似文献
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通过不同基质（A）、基肥（B）、施用不同根部追肥（C）对厚荚相思组培苗移植到圃地培育至出圃时的成活率的影响试验研究，结果表明，使用红心土：发酵木屑：炭化谷壳=5：3：2作为移植基质（A1）＋3kg·m^-3硫酸钾复合肥作为基肥（B2）效果最好，成活率达85．6％；采用200倍液植物信叶根部营养液作根部追肥（C2）最好，成活率达88．6％。 相似文献
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A basal area increment model for individual trees growing in even- and uneven-aged forest stands in Austria 总被引：10，自引：0，他引：10
Because of the gradual shift from pure even-aged forest management in central Europe, existing yield tables are becoming increasingly unreliable for forest management decisions. Individual tree-based stand growth modeling can make accurate stand growth predictions for the full range of conditions between pure even-aged and mixed-species uneven-aged stands. The central model in such a simulator is basal area increment for individual trees. Spatial information is not needed, and age and site index are intentionally not used to gain generality for all possible stand conditions. A basal area increment model is developed for all the main forest species in Austria: spruce (Picea abies), fir (Abies alba), larch (Larix decidua), Scots pine (Pinus sylvestris), black pine (Pinus nigra), stone pine (Pinus cembra), beech (Fagus silvatica), oak (Quercus robur, Quercus petraea and Quercus cerris), and for all other broadleaf species combined. The Austrian National Forest Inventory provided 5-year basal area increment from 44 761 remeasured trees growing on 5416 forested plots in the 1980s. This large sample is representative of forest conditions and forest management practices throughout Austria and therefore provides an excellent data base for the development of an increment model. The resulting increment model explained from 20 to 63% of the variation for all nine species and from 33 to 63% of the variation if the minor species Pinus cembra is excluded. These results compared quite closely with those of Wykoff for mixed conifer stands in the Northern Rocky Mountains. In the Austrian model, size variables (breast height diameter and crown length) accounted for 14–47% of the variation in basal area increment, depending on tree species. The best competition measure was the basal area of larger trees, which provides a tree-specific measure of competition without requiring spatial information; crown competition factor provided only minor improvement. Competition variables accounted for 9% of the variation on average, and up to 15% for some species. Topographic factors (elevation, slope, aspect) explained up to 3% of the variation, as did soil factors. Remaining site factors; such as vegetation type and growth district accounted for a maximum of 3% of the variation in increment. In total, site factors explained from 2 to 6% of the variation. Even though site factors account for a small percentage of the variation, they are not only significant, but serve to localize a particular prediction. These species-specific interrelationships between basal area increment and the various size, competition, and site varibles correspond quite well with ecological expectations and silvicultural understanding of these species in Austria. Because the sample base is so strong, the resulting growth models can be recommended not only for all of Austria but for surrounding regions with similar growth conditions. 相似文献
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Drought inhibits photosynthetic capacity more in females than in males of Populus cathayana 总被引：1，自引：0，他引：1
We investigated sex-related photosynthetic responses to drought in the dioecious species, Populus cathayana Rehd. Plants were subjected to two watering regimes (100% and 30% of field capacity) in a semi-controlled environment. Drought significantly decreased leaf area (LA), total number of leaves (TNL), specific leaf area (SLA), relative water content, net photosynthetic rate (P(n)), transpiration (E), stomatal conductance (g(s)), intercellular CO(2) concentration (C(i)), light saturation point (L(SP)), apparent quantum yield (Phi), carboxylation efficiency (CE), light-saturated photosynthetic rate (P(max)), maximum efficiency of PSII (F(v)/F(m)) and maximum effective quantum yield of PSII (Yield), and increased the total chlorophyll concentration (TC), CO(2) compensation point (Gamma), non-photochemical quenching coefficient, peroxidase (POD) activity and carbon isotope composition (delta(13)C). Moreover, differences between males and females were detected in many of these responses. In the drought treatment, males exhibited significantly higher LA, TNL, TC, concentration of carotenoids (Caro), P(n), E, g(s), C(i), L(SP), Phi, CE, P(max), F(v)/F(m), photochemical quenching coefficient, POD activity and delta(13)C, but a lower SLA, chlorophyll a/b ratio, carotenoids/total chlorophyll ratio and Gamma than females. However, Caro, L(SP), Gamma, Phi, CE and POD activity were apparently associated with sex-related resource demands, because significant differences in these traits were detected between the sexes under well-watered conditions. Our results indicate that drought stress limits photosynthetic capacity more in females than in males. 相似文献
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以脲醛树脂作为浸渍剂,纳米SiO_2作为改性材料对速生桉木进行改性处理,以纳米SiO_2质量与脲醛树脂浸渍溶液固含量的质量比(W)、高温处理温度(H)和时间(T)作为影响因素,探究浸渍高温热处理改性对速生桉木力学性能的影响。研究结果表明:浸渍高温热处理能够提高桉木的握钉力、抗弯强度和抗弯弹性模量。当W为2%、H为180℃、T为4 h时,浸渍热处理桉木的径面和弦面握钉力达到了理想值;当W为1%、H为160℃、T为4 h时,浸渍热处理桉木的端面握钉力较为理想;当W为1%,H为160℃、T为2 h时,浸渍热处理桉木具有较好的抗弯强度和抗弯弹性模量。 相似文献