Damage Detection of Picea asperata Sawn Timber Beams Using Modal Flexibility Curvature

The local damages such as knots,decay, and cracks can be translated into a reduction of service life due to mechanical and environmental loadings.In wood construction,it is very important to evaluate the weakest location and detect damage at the earliest possible stage to avoid the future catastrophic failure.In this study,the modal testing was operated on wood beams to generate the first two mode shapes.A novel statistical algorithm was proposed to extract the damage indicator by computing the modal flexibility curvature before and after damage in timbers.The different damage severities,damage locations,and damage counts were simulated by removing mass from intact beams to verify the algorithm.The results showed that the proposed statistical algorithm was effective and suitable to the designed damage scenarios.It was reliable to detect and locate local damages under different severities,locations,and counts.The peak values of the damage indicators computed from the first two mode shapes were sensitive to different damage severities and locations.They were also reliable to detect the multiple damages.     

Identification of pests and assessment of their damage on Carapa procera and Lophira lanceolata in Burkina Faso,West Africa

Nontimber forest products are a source of income for women in rural African communities. However,these products are frequently damaged by insect pests. The present study investigates the diversity and damage rates of insect pests that attack Carapa procera seeds and Lophira lanceolata fruits. The experiment was set up in western Burkina Faso and, for C. carapa, consisted of pests collected from seeds that had fallen to the ground and from stockpiled seeds. For L. lanceolata, pests were collected from fruits on the trees, and on the ground. The collected samples were sent to the laboratory to estimate the proportion of damaged seeds/fruits and rear the insects. The results showed that Ephestia spp., Tribolium castaneum,Oryzeaphilus spp., and Tenebroides mauritanicus were the pests of Carapa procera seeds and Lophira lanceolata fruits. Ephestia spp. was recorded as the main pest of both C. procera and L. lanceolata, whereas T. castaneum was only detected from seeds of L. lanceolata. For C. procera,the stocks were the most infested(29 %) by Ephestia spp.The infestation rate of fruits of L. lanceolata by Ephestia spp. on trees(31.42 ± 3.75 %) was less than the rate of fruits by T. castaneum on the ground(44.00 ± 3.5 %). The different body sizes of Ephestia spp. may indicate the occurrence of two putative species, one from C. procera and another one from L. lanceolata. This work provides important information that could contribute to the setting up of a local-scale sustainable management framework for oil tree pests in Burkina Faso and surrounding countries.     

Extraction optimization of insecticidal compounds from Lysurus mokusin by response surface methodology

We optimized the extraction process of Lysurus mokusin(L.) Fr. insecticidal compound(LMIC) using response surface methodology with ultrasonic extraction(UE). The surface morphologies of maceration extract(ME) and UE residues were compared by scanning electron microscopy, and then the activity of LMIC on Lymantria dispar(Asian gypsy moths) larvae was determined. Results showed that the optimal condition of UE was followed by80 min of extraction time, 60% of ethanol concentration and 80 m L g~(-1) of liquid–solid ratio. The surface morphologies of UE residue were looser and rougher than ME residue. The corrected mortalities of LMIC on L. dispar larvae was 59.77%. This result indicated that L. mokusin was a good candidate as pesticide for pest management.     

Effect of Gap Size on Seedling Establishment of Tsuga longibracteata

Effects of three gaps which are large （118 m^2）, medium （86 m^2） and small （20 m^2）, respectively, and under canopy of Tsuga longibracteata forest on the seedling establishment of T. longibracteata were studied through seed burial experiments from December 2003 to January 2005 in Tianbaoyan National Nature Reserve of Fujian, China. The results showed that the area of gap had an evident effect on the seedling establishment of T. longibracteata. The seedling emergence rates of T. longibracteata in plots of large gap, medium gap, small gap and under canopy were 10%, 10%, 4% and 6%, representing an increasing trend along with the gap size increasing without a significant difference. Rain eroding and insects feeding were two main factors leading to seedling death. The larger the gap size was, the more seedlings were killed by rain erosion and the fewer seedlings were killed by insects feeding. The emergence time of seedlings was almost same in all plots while their death time was different respectively. The gap size had a significant impact on seedling survival rate. The seedling survival rate was highest in the medium gap plot （27.0%） and next to the highest in large gap plot （7.3%）, and seedling in small gap plot and under canopy plot died out after one growing season. Increased light supply in gaps was favorable for the seedlings growth and survival. Increased light supply in the large gap could enhance the growth of seedling leaf and root of T. longibracteata, and the seedling in turn allocated more dry mass to root and leaf, but it has little impact on the growth of stem. This research indicates that T. longibracteata is a pioneer species and its seedling establishment need a medium or large gap （〉50 m^2）.     

不同经营措施条件下泡桐幼林抗冰灾能力分析

Investigation was conducted to analyze the effect of management measures such as trunk cutting and fertilization on frost resistant capability of young paulownia (Paulownia sp. ) plantation which had been undergone heavy frost damage in early 2008 in southern China. Experimental sites were located in the Paulownia fortunei forest consisting of 2-poplar clonal plantations in Chaling County. Paulownia fortunei, treated by root planting, trunk cutting and fertilization was called 2B; the contrast was called 1B. The results showed that the tree height, DBH, height under branch and lateral branch diameter in 2B were, respectively, 19.19%, 11.36%, 180% and 13.8% higher than those in 1B. The number of lateral branches in 1B was 2.8 times that in 2B. The icicle pressure beared by 2B was only 60.21% of that in 1B. There was nearly no potential damage in the 9treatment plot with 98% of the plants in the freeze injury grade I. In contrast, 50% and 36% of the plants in the control plot were observed, respectively, in freeze injury grades II and Ⅲ. Based on the present investigation, it can to be concluded that the applied management measures are effective in enhancing the resistant capability of young poplar plantations to frost damage.     

Effects of thinning on wind damage in Pinus thunbergii plantation ——Based on theoretlcal derlvation of risk—ratios for assessing wind damage

Based on paper of “Theoretical derivation of risk-ratios for assessing wind damage in coastal forest“,wind damage in the pine coasteal forest,which was thinned at four levels in December of 1997,was investigated for four successive growing seasons.Besides wind damage,the wind profiles outside and inside the coastal forest stand and the distributions of optical stratification porosity (OSP) were also observed.Based on these data,risk-ratios of wind damage for both individual trees and stands were estimated according to the methods developed in “Theoretical derivation of risk-ratios for assessing wind damage in a coastal forest“.The results showed that risk-ratios of wind damage,which were calculated from the meen height and diameter only and from the combination of wind and stand sructure profiles,accurately predicted wind damage in the plantation.Relationships between different thinning ratios and incidence of wind damage showed that stand stability decreased soon after the thinning.This was due to the immediate effects of thinning on increasing the canopy roughness and wind load,and on decreasing the sheltering effects from surrounding trees.However,thinning strategies could improve the stability by long-term effects on growthand development of trees against extreme wind.Only canopy damage was recorded during the experimental period,no stem damage was found,even though the maximum 10-min wind speed outside the coastal forest attained 30.2m s^-1.The results obtained in this study indicate that thinning is the most effective silvicultural strategy available for managing coastal forest despite the increased probability of wind damage soon after thinning.     

Using Virus to Restore and Construct Stable Forest Ecosystem for Pest Insects Control

Using the viruses to sustainable control forest pest insects were reviewed in this paper. And the status of forest pest insects and bio-control technique in China were introduced. The criterion of stable ecological system and the methods of restoration and construction were also analyzed. Meanwhile, the experiment in which 4 species of insect viruses were used and successfully control the forest pest insects persistently indicate that the insect viruses play an important role in restoring and constructing stable forest ecology system.     

Operational impacts to residual stands following ground-based skidding in Hyrcanian Forest, northern Iran

Hyrcanian (Caspian) Forest in northern Iran has a richness of biological diversity, with endemic and endangered species. The usage of ground-based skidding is well accepted practice for the extraction of timber from the forest, but this operation has tended to cause the greatest environmental problems. The aims of the study were to evaluate and comparison of operational impacts, residual stand damage, regeneration, and to quantify these effects such as: the extent of the damage, wounding patterns, size and distribution after logging operations that utilized two different methods: short-log and long-log. A Timberjack cable skidder was used and the study location was in the Kheyrud Forest. Post harvesting assessment of damage to the residual stand was compared along skid trail by 100% inventory method and also for the assessment of regeneration damage along winching strips. The results show that along winching strips the percentage of damage to the regeneration was 44% and 36%, while the tree damages along skid trails reached 2.3% and 4.1% in the short-log and long-log methods, respectively. The greatest average amount of damage to a bole occurred along the first 1 m up from the ground (97%) and also within 4 m of the skidder centerline (80%). These results show that the short-log method causes less damage to the residual stand than the long-log method. Tree location to skidder trail appears to have a significant effect on the number and height of scars on a tree. Well designed and constructed trails should be wide enough to allow wood extraction from the forest. Damage to the residual stand might be reduced by proper planning and training of logging crews.     

Snow damages on trees of an uneven age in mixed broadleaf forests:effects of topographical conditions and tree characteristics

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.     

Residual tree damage along skidding trails in beech stands in Greece

We studied the damage caused to unfelled trees during skidding operations in four beech stands of northern and central Greece that were managed under differing harvesting systems.After timber was harvested we recorded and analyzed all damage to a width of 2 m along both sides of the skid trails.The percentage of damaged residual trees was 17–28 %.Higher numbers of saplings were uprooted or destroyed in parts of the stands with high natural regeneration.Most damaged trees suffered 1.33–1.90 wounds that were inflicted up to a height of 1 m above ground level.At all sites mean wound sizes were large,89–1190 cm2,and caused elevated risk of future fungal infection.The damage caused by skidding during timber harvesting can be minimized by better planning the harvest operations,and training forest workers in reduced impact logging.     

Control of Lymantria dispar L. by biological agents

The experiment on control ofLymantria dispar L by using different kinds of biological measures, including nuclear polyhedrosis virus (NPV) ofLymantria dispar L., BtMP-342, sex-attractant as well as botanical insecticide, was carried out in the forest regions of Inner Mongolia in 2003. Two concentrations (2.632×10⁶ PIB·ml⁻¹ and 2.632×10⁷ PIB·ml⁻¹) ofLymantria dispar L. NPV were sprayed on the 2rd-instar-larvae ofL. dispar and 70% and 77.8% control effect were obtained respectively. BtMP0-342 was applied to the 3rd- and 4th-instar larvae and the control effect was around 80%. The sex-attractant provided by Canada Pacific Forestry Research Center also showed a good result in trappingL. dispar adults. The self-produced botanical insecticide, which was extracted from a kind of poisonous plant distributed in Daxing'an Mountains, China, exhibited a good control result in controlling the larvae ofL. dispar, and 82% mortality was observed when spraying primary liquid of the botanical insecticide on the 3rd–5th-instar-larvae in lab. Foundation item: This paper was supported by Natural Science Foundation of Heilongjiang Province (C0235) and Youth Foundation of Harbin City (0061218024). Biography: ZHANG Guo-cai (1964), male, Ph. Doctor Candidate, associate professor in School of Forestry, Northeast Forestry University, Harbin 150040, P. R. China. Responsible editor: Song Funan     

The use ofBacillus thuringiensis on Forest Integrated Pest Management

Bacillus thuringiensis is a major microbial insecticide and a source of genes encoding several proteins toxic to insects. In this paper the authors give a brief summary ofBacillus thuringiensis used on the integrated pest management in forestry. The derivatives of Bt strain HD1 subspkurstaki have been widely used to control the forest pests such as the gypsy moth (Lymantria dispar), spruce budworm (Choristoneura fumiferana), the pine processionary moth (Thaumetopoea pityocampa), the European pine shoot moth (Rhyacionia buoliana) and the nun moth (Lymantria monacha). Some progresses of transferring and expressing Bt toxin gene in forest trees are offered with a discussion on the limits and future prospects of using Bt products in forestry. Biography: Li Gui-ming (1967-), male, engineer in Pingshan Forestry Chemicals Insecticides Factory, Harbin 150324, P. R. China Responsible editor: Chai Ruihai     

Labor-Versuche mit Neem-Samenextrakt zur Bekämpfung des Schwammspinners,Lymantria dispar L.

Effects of neem-extracts on cater pillars of the gypsy moth, Lymantria dispar L. The effects of neem extracts(Azadirachta indica) (0.02%; 0.2% 0.5%) were tested on caterpillars of the gypsy moth (Lymantria dispar). The laboratory experiments showed, that these concentrations suppress the development and prohibit the moultin of caterpillars. The mortality reached 100% in all experiments. Addition test carried out under field conditions indicated that the activity of neem extract sprayed on oakleafs(Quercus robur) remained unchange after 12 days of application.     

Cymolomia hartigiana (Saxesen, 1840) (Lepidoptera: Tortricidae) attacking toAbies nephrolepis max. new to Daxing'anling, Heilongjiang, China

An Olethreutine speciesCymolomia hartigiana (Saxesen, 1840), attacking toAbies nephrolepis Max., is reported for the first time from Daxing'anling, Heilongjiang, China. The morphological characteristics are briefly re-described with illustrations. Also its damage and biology are noted. Foundation item: This study was carried out under the financial support by KOSEF (Korea Science & Engineering Foundation) with the program of “Korea and China Young Scientist Exchange Program” (2002–2003). Biography: *BYUN Bong-Kya (1963-), male, Ph.D., Researcher in Korea National Arboretum, Korea. Responsible editor: Chai Ruihai     

Effect of Neem extract on Lymantria dispar L. (Lepidoptera: Lymantriidae) and Leptinotarsa decemlineata Say. (Coleoptera: Chrysomelidae)

High antifeedancy and low toxicity of the plant preparation Neem (azadirachtin), on the gypsy moth, Lymantria dispar L. larvae were proved under laboratory conditions. A high index of Neem antifeedancy was confirmed in all tested concentrations. Under laboratory conditions the Neem had satisfying antifeedancy on Leptinotarsa decemlineata Say third instar larvae too. Field experiments also proved that the foliage protective effect of Neem was very significant. Experiments showed that some antifeedants or repellents, such as Neem, should control olygophagous (L. decemlineata, Coleoptera) insects as well as very polyphagous insects such as L. dispar (Lepidoptera). As a biological, plant-derived preparation, Neem could be suitable for integrated pest management (IPM) programs, especially in small orchards, parks, and tree rows in urban environments and on small private gardens.     

Eine neue Virose beim Schwammspinner,Lymantria dispar L. (Lep., Lymantriidae)

A new virosis in caterpillars of Lymantria dispar L. (Lep., Lymantriidae) Caterpillars ofL. dispar found in the Apennin-mountains near Genua, Italy, showed a new virosis in a low percentage. The pathogen is characterized by the enormous dimensions (max. 20 ) and the cubic form of the polyhedra. It causes a nuclear hypertrophie particularly within the haemocytes,     

Effect of midgut infection with the microsporidium <Emphasis Type="Italic">Endoreticulatus schubergi</Emphasis> on carbohydrate and lipid levels in <Emphasis Type="Italic">Lymantria dispar</Emphasis> larvae

Lymantria dispar (Lep., Lymantriidae), an important forest defoliator, is host for a variety of entomopathogenic microsporidia. These are obligate intracellular parasites that completely depend on resources provided by the hosts. The microsporidia infecting L. dispar differ in the host tissues that become infected as well as in virulence, with presumably different effects on host physiology. Endoreticulatus schubergi infects the midgut tissue of the host; its virulence is low. We studied the effects of infection with E. schubergi on carbohydrate and lipid levels in the L. dispar host larva. Trehalose titer in the hemolymph increased with larval age. There were no significant differences between infected and uninfected hosts. Glycogen content of the host tissue also increased with age. Levels of this storage carbohydrate were significantly lower in infected larvae at a late stage of infection when insects were either full grown larvae prior to pupation (57.4 ± 5.7 and 36.4 ± 5.2 μg/mg in uninfected controls and infected hosts, respectively) or prepupae (53.2 ± 3.4 vs. 34.7 ± 4.7 μg/mg). Lipid levels in host tissue likewise increased over time and were slightly but not significantly lower in infected L. dispar at a late stage. The results suggest that L. dispar larvae are able to compensate for most of the loss of nutrients to the developing microsporidia. Differences between these findings and the effects of infection with the virulent microsporidium, Vairimorpha disparis, that infects the host’s fat body and causes severe depletion of nutrients in L. dispar larvae are discussed.     

Life circle and bionomics ofLymantria dispar L.

The life circle and bionomics ofLymantria dispar was studied from the May to the July of 1997 in Tulihe Forestry Enterprise of Inner Mongolia. The results showed thatL. dispar has one generation in a year, larvae overwinters in eggs, and last 50 days to grow up. From the completing of larvae period to the appearing of adults lasts 11 days. The study made a basis for the period forecasting of L.dispar in Inner Mongolia.     

昆虫对植物挥发性信息化合物的影响与利用

昆虫能影响、利用植物的挥发性信息化合物。昆虫通过取食时产生的口腔的分泌物改变植物挥发性信息化合物的释放,这种改变不同于由机械损伤诱导的改变,这两种情况下释放的挥发性信息化合物具有不同的生态学意义。昆虫对植物挥发性信息化合物的诱导释放具有系统性和群体性,并能利用寄主植物特有的挥发性信息化合物寻找适宜的行为场所,利用植物在不同诱因下挥发性信息化合物的改变避免昆虫种内、种间的生存竞争。研究昆虫对植物挥发性信息化合物的影响与利用,可以帮助人类寻找害虫的自然控制因子,探索环境友好型害虫防治途径。     

落叶松人工林重要害虫天敌——大腹圆蛛生物学特性及其对害虫控制作用的研究

大腹圆蛛(Araneus ventricosus)在吉林省2年完成1代,跨3个年度,以1-2龄和6-7龄若蛛越冬。该蛛除卵期及1、2龄蛛外,其它龄态的若、成蛛均张网捕食生活。该蛛喜居有光的栖境,在林缘、林窗处、路旁处结圆形垂直网,昼伏夜出,在小雨条件下可以正常活动。大腹圆蛛对小型猎物可直接取食,对中、大型猎物,需缠绕成束的捕获丝缚住再取食。在林间大腹圆蛛可取食多种蛾和叶蜂成虫,包括兴安落叶松鞘蛾、落叶松毛虫、黄褐幕枯叶蛾、舞毒蛾、栎毒蛾、松皮小卷蛾、松廮小卷蛾、伊藤厚丝叶蜂和落叶松叶蜂等多种落叶松害虫,是一种有效的害虫天敌。