共查询到20条相似文献，搜索用时 312 毫秒
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从群落学角度出发,通过群落特征指数和典型相关分析的方法,分析枣园植物群落、景观的结构特征以及日本龟蜡蚧发生程度与植物群落、景观多样性之间的关系.结果表明:根据群落相似性,不同样地枣园植物群落可归为平原和丘陵地区2类,前者群落多样性、均匀性较低,日本龟蜡蚧危害程度高;丘陵地区则表现为植物群落多样性、均匀性较高,而日本龟蜡蚧发生程度相对较低.典型相关分析结果表明:日本龟蜡蚧发生状况与枣园植物群落性状显著相关, 在景观特征指数上,也表现出与植物群落相类似的平原与丘陵地区的差别,在景观性状中,景观多样性和荒地比例对日本龟蜡蚧的影响最强.景观多样性较高、荒地比例较大的地区,日本龟蜡蚧的危害程度较低. 相似文献
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经调查，在石家庄市郊区柿园蚧虫有６种：柿绒蚧、柿真棉蚧、日本龟蜡蚧、角蜡蚧、草履蚧、桃树木坚蚧，其中前两者为优势种，柿真棉蚧为国内新纪录。其发生特点是数种混合发生，但以一种为主。对柿树物候和主要蚧虫的生活史观察表明：蚧虫的发生与柿树物候期有一定相关性，从而确定了灭虫的最有效时间是：柿绒蚧在柿树结果后、果膨大前（６月１０日前后）；柿真棉蚧在柿果膨大前后（６月中旬）；日本龟蜡蚧在果膨大以后（６月下旬）；草履蚧在柿树芽萌动时期（３月上旬）。控制柿树蚧虫的危害，仍应以化防为主，保护利用天敌为辅。用久效磷或氧乐果喷雾防治，虫口减退率在９４％以上，辅之以久效磷涂梢，防效可达１００％。 相似文献
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枣龟甲蜡介壳虫属同翅目，蜡蚧科，又名日本龟甲蚧、日本蜡蚧、枣龟甲蚧、龟蜡介壳虫。俗称树虱子、枣虱子。分布很普遍，寄主较广泛，为害植物达100多种，主要危害枣、柿、梨、苹果等，是近年来我国枣产区发生的主要虫害。严重发生时树枝枯死，落叶落果，严重减产，以至绝产。 相似文献
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辛荑树型优美、花大而芳香,南阳市把它作为道路绿化的主要树种之一.近几年,发现日本龟蜡蚧壳虫为害辛荑,且呈逐年加重、不断蔓延的态势.被其危害的辛荑,树叶发黑,枝干干枯,树势减弱,严重时整株死亡.通过研究与实践,采取了一系列防治措施,有效地控制了此虫的危害,现将日本龟蜡蚧壳虫的识别与防治介绍如下： 相似文献
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枣树日本龟蜡蚧防治技术研究 总被引：3，自引：0，他引：3
采取化学防治与生物防治措施对枣树日本龟蜡蚧进行防治试验，结果表明：在蚧卵孵化率达４０％～５０％时，使用２５％广克威乳油１０倍液树干涂环防治效果达９０％以上；在蚧卵孵化率达７０％～８０％时，使用２５％广克威乳油５０００倍液或４０％氧化乐果乳油１０００倍液或２４％万灵水剂２０００倍液喷雾防治，效果分别达９６．６８％，９３．３８％和９５．２３％；该蚧天敌种类较多，保护与利用这些天敌可在一定程度上控制日本龟蜡蚧的为害。 相似文献
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Liu HuirongNortheast Forestry University 《林业研究》1993,4(2):11-17
The plantations of korean pine(Pinus koraensis)and scots pine(Pinus sylvesrisvar.mongolica)are mainly pure stands.Fires are gradually causing problems in theseplantations and being paid much more attention recently.Study on the influence of fire ontrees and the adaptation to fire,therefore,is of great important to probe the fire ecologicalproperties and the protection ways of these two species.The results are as follows:Bothof the species are easily damaged by fire,but korean pine is more susceptible.In the samefire,korean pine is damaged more seriously than scots pine although they have the samesize.Young individuals have low fire resistant capacity and can be damaged seriously,andolder ones have strong fire resistance and can be damaged lightly.Up-hill fire makes aserious damage to the trees distributed in up-slopes with the reason of higher fireintensity.Down-hill fire makes a serious damage to the trees distributed in down-slopcswith the reason of higher fire severity.The larger deocambium area in t 相似文献
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Several heavy wet snowfalls occurred during 2007-2009 across a broad-scale thinning and fertilization experiment to bring overstocked juvenile lodgepole pine (Pinus contorta var. latifolia) in the foothills of Alberta, Canada into an intensive management regime. We examined the bending and breakage of trees in relation to thinning and fertilization and used a multimodel information-theoretic approach to model stand and tree level predictors of snow damage. Fertilized stands suffered the greatest amount of snow damage, and this was most noteworthy when stands were also thinned; here 22% (17% broken stems) of trees were damaged compared to 8% (4% broken stems) in the thinned and unfertilized stands. At the stand level, needle weight and crown cover were reliable predictors of snow damage. At the tree level, separate models were developed for each combination of thinning and fertilization. All models used total tree volume; usually the smaller trees in the stands were more susceptible to damage but in the thinned and fertilized stands larger but slender trees with large asymmetrical crowns tended to be damaged. Also, trees with lower total stem volume were more susceptible to damage. Only in the thinned and fertilized stands were variables related to crown shape and asymmetry important predictors of snow damage. We conclude that snow damage is an important agent for self-thinning in unthinned stands and fertilization tends to exacerbate damage because of increase in foliage size. In areas with regular occurrence of heavy snow, we do not recommend fertilization at the same time as thinning, as the larger and more economically important trees in the stand are at risk. 相似文献
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Collybia fusipes is a common cause of root rot on oak in the north of France. Collybia fusipes basidiomes can be as frequent on oaks in stands where no decline of the trees occurs compared with stands where the decline is chronic. This might be explained by differences in the amount of roots damaged by the parasite. To test that hypothesis, 430 oak trees, Quercus petraea, Quercus robur and Quercus rubra, located in six forests were selected. Half of them showed C. fusipes basidiomes at the trunk base. The association between presence of basidiomes and decline of affected trees depended on the forest. The level of infection of each tree by C. fusipes, as well as the crown appearance, the tree height : diameter at breast height ratio, age and sapwood width were determined. The presence of C. fusipes basidiomes was always associated with significant root infections. The crowns of the trees deteriorated with increasing level of root infection and the decline was severe only when the root damage was heavy. Although the decline of trees that were heavily damaged by C. fusipes was severe in some of the stands, in others, it was only mild, and so the differences in tree decline between the stands could not be attributed solely to differences in root infection severity. Trees damaged by C. fusipes seemed not to be subjected to more competition than their undamaged neighbour as reflected by a similar tree height: diameter at breast height ratio. 相似文献
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Hashimoto R 《Tree physiology》1990,6(2):119-134
Crown form, vertical changes in branch inclination and vertical distribution of foliage density in a young sugi (Crytomeria japonica D. Don) stand were analyzed using allometric equations. Tall trees had deeper crowns than short trees, whereas the crown diameters of both tall and short trees were similar. Apical roundness was more pronounced in the lower-story trees, which were characterized by umbrella-shaped crowns. The vertical distribution of foliage density was approximated by a nearly symmetrical curve. Tall trees had higher spatial densities of foliage than short trees. Branch inclination also varied significantly with tree height. The middle-story trees had the largest branch inclinations and the lower-story trees had the smallest branch inclinations. Even in young uniform stands, crown morphology and structure were modified in response to the light environment. 相似文献
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Farzam Tavankar Angela Lo Monaco Mehrdad Nikooy Rachele Venanzi Amireslam Bonyad Rodolfo Picchio 《林业研究》2019,(4):1383-1394
Snow damage on natural stands is an important problem concerning mountainous forest management.In the present research,the frequency and intensity of heavy snow damage on natural stands and the relationship of damages with characteristics of trees,stand and topography were studied in mountainous forests of northern Iran.A systematic sampling design was applied to the study area(140 ha),with 122 circular plots.The grid dimension was100 m and each plot area was 1000 m^2.The four types of snow damage to trees include:crown damage(8.6%),stem breakage(5.4%),uprooting(3.2%),and bending(1.4%).The frequency of crown damage grew with an increase inthe diameter at breast height(DBH),while the frequency of stem breakage,uprooting and bending decreased with an increase the DBH.The frequency of crown damage,stem breakage,and total damages was related to tree species(p<0.01).Not all tree species were equally susceptible to snow damage.The amount of damage grew with increasing elevation and slope angle and decreased with increasing soil depth.Young trees(DBH<25 cm)were more susceptible to snow damage than other trees.Snow damage decreased by as the trees in the stand became more mixed in age.The susceptibility of trees to snow damage increased by height and slenderness coefficient.With adequate silvicultural operation,snow damage can be reduced to a minimum level in these natural forests. 相似文献
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油松—白桦混交林种间关系研究 总被引：4，自引：0，他引：4
在调查河北隆化县油松－白烨混交林的林木生物量（地上部生物量及根系生物量）、林下草灌木、林地枯落物的总量以及不同混交距离油松地上地下部分生长发育状态的基础上，研究了混交林的种间关系。结果表明，该混交林作为华北地区广泛分布的一种林型，林下草灌木繁茂，林地枯落物分解迅速，有利于土壤理化性质和林分营养状况的改善，种间关系处于基本协调状态。由于林龄及密度原因，混交林生物量略低于油松纯林，在混交林中白桦对油松的生长有一定的抑制作用，抑制作用因混交距离而变化。本文提出了合适的混交距离和混交方式。 相似文献
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Dendrolimus superans (Butler) occurred in the vast areas of Daxing’an Mountains forest, in Heilongjiang Province, in 1990. Stands damaged byI). Superans seriously, intermediately and lightly show patch shape distribution within damaged area. By ordination analysis and correlation
analysis between ordination factors and coordinate axis. It was found that occurrence ofD Superans in different extent is owing to the effect of forest age, composition and exposure. The tended young pure forests grown on
the sunward slopes are most seriously damaged and non-tended middle-age mixing stands grown on the sunless slopes are most
lightly damaged. Therefore, in order to preventD. superans from seriously damaging larch forests, relatively large crown density (P > 0. 7) should be kept, and broadleaf trees should
be also properly preserved.
This research project was supported by Scientific and Techndogical Committee of Heilongjiang Province 相似文献
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Species diversity of broad-leaved trees in Cryptomeria japonica plantations in relation to the distance from adjacent broad-leaved forests 总被引：1，自引：0，他引：1
Jiro Kodani 《Journal of Forest Research》2006,11(4):267-274
The species diversity of broad-leaved trees in relation to the distance from a broad-leaved forest was investigated in Cryptomeria japonica plantations with crown snow damage near the Japan Sea in central Japan. The number and diversity of species and stem density
decreased with distance from the broad-leaved forest in maturing gap stands (51–58 years old; >10 years after crown snow damage),
but not in recent gap stands (34–42 years old; <10 years after crown snow damage), and increased with improved light conditions
in the interior of recent gap stands, but not in that of maturing gap stands. The stem densities of tall and small tree species
and woody lianas were greater in the interior of recent gap stands than in maturing gap stands. Woody lianas, which are characteristically
shade intolerant, had a high stem density in the interior of recent gap stands. In contrast, the stem density of shrubs was
greater in maturing gap stands than in recent gap stands, irrespective of distance. Shade-tolerant shrubs had a high stem
density in maturing gap stands. Wind-dispersed and frugivore-dispersed species were concentrated at the edges of maturing
gap stands, but some frugivore-dispersed species, which may persist in soil seed banks, occurred in the interior of recent
gap stands. Gravity-dispersed species tended to occur both at the plantation edge and in the interior. The differences in
the occurrence patterns of broad-leaved trees in the two types of stands reflected the difference in the effect of both the
distance from the adjacent broad-leaved forest and the light conditions related to canopy gaps, with the time since gap formation
in a region where crown snow damage often occurs. 相似文献
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Maritime pine (Pinus pinaster Ait.) is the tree species most affected by wildfire in the Iberian Peninsula. Prediction of the probability of fire-injured tree mortality is critical for management of burned areas, evaluation of the ecological and economic impact of wildfire and prescribed fire planning and application. Pine bark beetles (Scolytidae) frequently attack burned maritime pine stands and cause extensive post-fire mortality throughout the Iberian Peninsula. In the present study, maritime pine trees were monitored for three years following 14 wildfires in four ecotypes in Spain (11 fires in Galicia (Galician ecotype - NW Spain), one fire in Portillo (Meseta-Castellana ecotype - Central Spain), one fire in Rodenal (Rodenal ecotype - Central Spain), and one fire in Genalguacil (Sierra Bermeja ecotype - SW Spain)). Data on tree attributes, crown and bole injury, ground fire severity, Ips sp. presence and tree survival were obtained by examining 3085 trees. Logistic regression models for predicting the probability of delayed maritime pine mortality were developed by use of generalized estimated equations (GEE). An ample range of response to fire damage in mortality was evident among the four ecotypes and different models were fitted for each. The most important variables for predicting tree mortality were total crown volume damaged, presence of Ips sp. attack and cambium kill rating. The results highlight the extensive presence of Ips sp. in burned maritime pine forests and its importance in tree mortality process, the ample range of response of P. pinaster, in terms of post-fire mortality, as well as the need to develop site specific mortality models for the different ecotypes of this species following fire. 相似文献
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We investigated the distribution and frequency of damage to tree stands adjacent to low-volume roads according to the type of hillside materials involved(soil or rock) and hillside gradient in mountainous forests of northern Iran. A total of 80 plots were systematically and randomly sampled to record damaged trees(bending,crushing and wounding) by class of hillside gradient and materials at the edge of road. Tree wounding and crushing at rock slopes was significantly greater than at hillsides with a mix of clay soil(p \ 0.05). Damage on hillsides with slope gradients[45% were 2, 8.5 and 2.3 times more frequent than on hillsides with slope gradient\15% for bending, crushing and wounding, respectively. The damage distribution varied according by type and the most frequent damage was tree wounding(p \ 0.05). The damage distribution was measured at distances of 4, 5 and 8 m from the road fillslope for tree bending, crushing and wounding, respectively. Using hydraulic excavators and physical barriers(wooden obstruction and synthetic holder) during earthworks for road construction could reduce these damage. 相似文献