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1.
尺蛾是蛾类昆虫中的一大科,在海南岛尖峰岭共采得标本440余种,现已定名87属126种及亚种。其中有优势属Comibaena、Luxiaria、Semiothisa、Tanaorhinus和Terpna 5属;有优势种Cleora determinata、Fascellina chromataria和柑桔尺蛾Hemerophila subplagiata等16种。本科种群虫口密度与当地蛾类其他各科相比,数量较大。其生态分布以热带山地雨林种类最多,成虫出现以4、5月种类最多,诱虫量则以1、5月为最高。 相似文献
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在海南岛尖峰岭采到刺娥科昆虫有４２种，其中已定名者２０种，隶属１３个属，显脉球须刺蛾广东亚种、素刺娥和灰双线刺蛾３种（含亚种）为灯下优势种；绒刺蛾为自然界间隙性大发生的优势种。在定名刺蛾中，有中国新记录１种，海南省新记录１４种。其生态分布，以热带山地雨林类型种类最多。地理分布以扁刺蛾、素刺蛾和灰双线刺蛾等范围较广，从昆虫地理区划分，东洋区种类占７５％。成虫出现期有１～１１个月不等 相似文献
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尖岭的螟蛾科昆虫是当地蛾类中三大科之一，采用黑光灯诱蛾，共得标本360余种，已定名8亚科61属95种，约占1／4强；其中野螟亚科为优势亚科；缀叶野螟属、卷叶野螟属、蛀野螟属和绢野螟属是优势属；条纹绢野螟、黄环绢野螟和白斑黑野螟等10种为优势种，螟蛾的生态分布，以热半落叶季雨林虫种数最多。优势种的成虫多在下半出现，尤以9月份为最多。 相似文献
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尖峰岭林区的昆虫所采到的标本共有20目约4000余种,其中鳞翅目种类最多,其次为鞘翅目、双翅目、膜翅目、半翅目、直翅目、同翅目等。以蛾类为例,灯诱所得虫种数是夜蛾科、尺蛾科和螟蛾科最多,每虫种平均诱到的虫数是燕蛾科和拟灯蛾科最多。在这当中佩夜蛾和条纹绢野螟是数量最多的虫种。从鳞翅目13个科来看,热带山地雨林中分布的种类最多,以下的次序是热带半落叶季雨林、山顶苔藓矮林、热带常绿季雨林。热带山地雨林中植物种类和灯蛾种类均最多,而热带半落叶季雨林中两者的种类均最少。再从两个森林类型之间植物与灯蛾的共有种来说,亦以热带山地雨林为最多。由此可见,该类型是植物和蛾类昆虫种类组成上的中心,并有向上和向下递减的趋势。一些实例证明,天然林中的害虫,当转入人工纯林后,常发展成灾。热带林区昆虫的特点是种类多,数量少,世代多,无休眠,有滞育。 相似文献
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为合理利用和保护丹东地区野生乡土观赏植物资源,对丹东地区野生乡土观赏植物资源的分布规律、生活型和观赏性进行调查。结果表明:丹东地区野生乡土观赏植物有76科180属290种,其中以双子叶植物为主,共213种,占野生乡土观赏植物总种数的73.4%;多年生草本野生乡土观赏植物144种,占49.7%;观花类野生乡土观赏植物种数最多,为232种,占46%;优势科是百合科、蔷薇科,无绝对优势属,相对优势属是百合属、槭属。 相似文献
7.
保定市城市绿地植物多样性研究 总被引：4，自引：0，他引：4
城市生物多样性是城市生态系统的主要构成,以保定市各类绿地植被为对象,根据资料收集和实地调查的数据分析比较。结果表明,市区物种集中在少数大科中,如豆科、禾本科、菊科等,优势种较集中。在生活型上草本种数最多,乔木次之,植物群落以落叶树为主。在物种来源方面乡土树种比例较大,引进物种也是其城市绿地植被的重要组成部分。垂直群落类型以乔灌草及乔草类型为主。不同绿地类型中,公园绿地植物科、属、种的丰富度均处于绝对优势;且均为草本种数〉乔木种数〉灌木种数〉藤本种数。各类绿地中,乔木均匀度指数为最高,灌木其次,草本最小。乔木层的多样性水平最高,灌木层其次,草本层最低。并通过分析得出在城市绿地生物多样性保护中不仅要有较高的丰富度,也要重视物种的均匀度,充分利用乡土树种,合理引进外来物种。 相似文献
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生物多样性是城市绿地系统的主要构成因素,该文以邢台市城市绿地为研究对象,通过实地调查和资料收集的数据,进行比较、分析、总结。结果表明:该市区物种集中在少数大科中,如豆科等,优势种较集中。在生活型上草本种数最多,灌木次之,植物群落以落叶树为主。不同绿地类型中,公园绿地植物科、属、种的丰富度均处于绝对优势;且均为草本种数>乔木种数>灌木种数>藤本种数。各类绿地中,乔木均匀度指数为最高,灌木其次,草本最小。乔木层的多样性水平最高,灌木层其次,草本层最低。最后,通过分析得出:在城市绿地生物多样性保护中不仅要有较高的丰富度,也要重视物种的均匀度,充分利用乡土树种,合理引进外来物种。 相似文献
10.
陕西牛背梁国家级自然保护区大型真菌区系特征研究 总被引：1，自引：0，他引：1
通过对陕西省牛背梁国家级自然保护区大型真菌的调查和研究,结果表明:本保护区共有真菌165种,隶属2门4纲10目35科79属,其中以担子菌门层菌纲真菌的种类数量最多,为144种,占保护区大型真菌总种数的87.3%;共有优势科9个含47属111种,分别占保护区大型真菌总科数的26.5%、总属数的59.5%,总种数的67.3%;本区大型真菌主要集中分布在海拔2 300m以下的区域,共有159种,占保护区大型真菌总种数的96.4%,大型真菌的种类、种群密度以及数量随着海拔升高而递减。从大型真菌在不同植被类型内分布看,大型真菌以分布于阔叶林带的种类较多,达126种,占调查总种数的76.4%,其次为灌丛林和针叶林。 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
12.
《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
13.
Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and
also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the
amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter
bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K
was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed
significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week−1 for leaves and from 0.0225 to 0.0633 week−1 for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed
during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly
between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species
provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient
enrichment capacity and slower decomposition rates which would minimize leaching losses.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
《Scandinavian Journal of Forest Research》2012,27(2):118-130
The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions. 相似文献
15.
《Wood material science & engineering》2013,8(2):76-84
Abstract Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists. 相似文献
16.
Steven Maranz Amadou Niang Antoine Kalinganire Djeneba Konaté Bocary Kaya 《Agroforestry Systems》2008,72(3):231-239
Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional
data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral
contents and B1 and B2 vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising
germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B1 88 mg 100 g−1, B2 187 mg 100 g−1, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal
diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties
to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations. 相似文献
17.
Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered. 相似文献
18.
《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
19.
《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
20.
本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献