杨干透翅蛾的研究

杨干透翅蛾是杨树的一种新的蛀干害虫。在西宁地区蛀害指数达43—79％,2年1代。成虫分主、副两组,6月和8月为发生盛期,幼虫侵蛀期主要在7月中、下旬和9月下旬—10月中旬。幼虫计有8龄。当年侵蛀后可长至1—4(5)龄;第二年可长至6—7(8)龄,在林木边材中造成“L”形蛀道;于第三年相继在蛀道内作茧化蛹、羽化。因有二个发生年度不同的群体相互演替,故每年都有一批成虫和初孵幼虫出现。树龄10年左右,胸径17.77±4.42厘米的四旁杨树最易受害;树干胸高1米以内和树冠基部分枝点附近,着卵最多,蛀害也最严重。侵蛀盛期喷布50％磷胺乳剂50—100倍液,毒杀小幼虫;辅以40％乐果乳剂或80％敌敌畏乳剂原液注孔,熏杀中、老龄幼虫。     

柿树主要病虫害综合治理

在河南焦作地区柿树主要病虫害有8种，以柿蒂虫、日本龟蜡蚧危害严重。蛀果率在30％以下时，采取人工防治；当蛀果率达30％以上时，采取综合防治，平均防治率达90％左右。     

多毛小蠹虫生活习性及防治技术研究

多毛小蠹１年发生２代，世代极不整齐，有在蛀入孔潜伏交尾习性。防治以清除枯死，濒死枝干，烧掉剥皮，加强管理提高树势，药剂防治宜在成虫新蛀入后筑母坑道之时；采用１：１００００倍敌杀死，速灭杀丁或１：１０００倍的敌敌畏，辛硫磷，效果可达９５％。     

利用引诱剂和肿腿蜂防治松墨天牛的研究*

松墨天牛是松树的主要蛀干害虫,亦是松材线虫病的主要传播媒介。利用引诱剂能够大量诱集松墨天牛,使用浓度以1:3较为经济实用。1号引诱剂诱虫能力最强,1、2号混合液及4号诱虫效果次之。诱虫量一般比对照提高17.8～54.9倍,比伐倒木提高1.2～3.2倍,比病虫枯死木提高5.8～7.2倍。诱集后可降低林木枯死率2％～32％,防治效果达70％～95％。施引诱剂的同时再施1:1的氧化乐果稀释液可毒杀62.4％～100％的天牛幼虫。每公顷释放管氏肿腿蜂28 142头,当代防治效果可达40％～50％,经3～4个月持续防治效果可达69.6％～85.3％。     

马尾松林油松球果小卷蛾发生及防治

油松球果小卷蛾钻蛀马尾松雌球花，２年生球果和嫩梢。该虫在浙江省一年发生１代，以蛹在土内越冬。本文报道了成虫的羽化规律，幼虫钻蛀及转移习性。该虫各虫态发生期与松实小卷蛾，芽梢斑螟等钻蛀性害虫发生的相关性；马尾松林中油松球果小卷蛾与松实小卷蛾的种群比率。通过试验，提出马尾松种子园４月中旬喷洒２０％杀灭菊酯乳油１５００倍液，防治效果达９０％以上。     

双条杉天牛生物学特性观察与无公害防治

双条杉天牛在济南1年发生1代，以成虫在被害树木蛀道内越冬，翌春3月上旬成虫开始出蛰，3月中、下旬进入出蛰盛期，3月底为末期；4月中、下旬幼虫大量孵化蛀入树干危害；8月下旬陆续化蛹，9月上旬为化蛹盛期；9月下旬成虫开始羽化．10月中旬为成虫羽化盛期，10月下旬为末期。成虫羽化期树干喷布200倍1％的绿色威雷Ⅱ号杀灭成虫，虫株率、虫口密度和受害死亡率较对照分别降低18．5％、2．5头，株和7．4％；林间设饵木引诱成虫产卵效果良好，受害率可降低3．4％；幼虫危害期林间释放管式肿腿蜂，寄生率较空白对照高47．3％以上；及时进行卫生伐，砍除受害树木，消灭虫源，对控制其危害起到较大作用，受害率可降低2．4％。     

四种药剂防治云杉阿扁叶蜂试验研究

云杉阿扁叶蜂（Ａｃａｎｔｈｏｌｙｄａ ｐｉｃｅａｃｏｌａ）是分布于祁连山林区危害青海云杉的主要害虫，蔓延迅速，危害严重。用药品进行防治试验，表明野外用２５％灭幼脲Ⅲ号胶悬剂４０００倍、２．５％功夫乳油１００００倍、８０％敌敌畏乳油８００倍、２．５％敌杀死乳油３０００倍稀释液常量喷雾，２５％灭幼脲Ⅲ号胶悬剂１００倍、２５％灭幼脲Ⅲ号胶悬剂加２．５％功夫乳油（１００＋２０００倍）稀释液超低容量喷雾杀虫     

赣林1号树干注射防治杨小舟蛾试验

报道了利用树干注射赣林１号农药，对杨树食叶害虫杨小舟蛾幼虫的防治效果１００％，同时兼有抑制蛀干害虫星天牛的侵害，又能促进杨树胸高直径的生长     

椰子织蛾生物学特性观察和防治

椰子织蛾（Opisina arenosella）是棕榈植物重要食叶害虫，在湛江一年发生 4~5 代、以 4 代为 主，世代重叠，以高龄幼虫越冬。每年 7—8 月份林间种群数量最大，8—9 月份危害严重，幼虫主要在 植物中层和下层老叶叶片背面皱褶处危害，形成不规则蛀道。蛀道长 60~150 mm，蛀道内粪便与其吐的 丝交织，幼虫隐藏于蛀道内取食叶肉，严重时叶肉大部分被吃光，后期造成叶片卷曲、干枯，形似火烧。 害虫完成 1 世代历期 50~65 d，其中幼虫历期 30~35 d，蛹历期 10~14 d，成虫历期 5~10 d, 卵历期 4~6 d。 车载电动喷雾器防治试验结果表明，20% 好年冬乳油 1 200 倍液、44% 多虫清乳油 1 200 倍液和 50% 甲 刻水分散粒剂 800 倍液，喷药后第 5 天，3 种药剂对椰子织蛾幼虫防治效果达到 90.26%~93.38%；喷药后 第 10 天，防治效果达到 93.16%~95.24%；3 种药剂的防治效果不存在差异。推荐交替使用上述 3 种药剂， 相隔 10~15 d，连续防治 2~3 次，可以控制其危害。     

花椒白蜡绵粉蚧的生物学观察和防治

白蜡绵粉蚧在涉县主要为害花椒，１年１代，以若虫在枝干上越冬。若虫和成虫活动期，可用９６８８－Ⅰ号或９６８８－Ⅱ号农药稀释１０倍液涂干或分别喷洒５０％辛硫磷、４０％久效磷、１０％克蚧灵乳油１０００倍液，毒杀活动若虫和成虫。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

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.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

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.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

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.     

Modelling of adequate pretwist for obtaining straight timber

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.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

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.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Development of Pinus sylvestris Main Stems Following Three Different Precommercial Thinning Methods in a Mixed Stand

Reducing competition by point cleaning may be an attractive alternative to conventional precommercial thinning in forestry. In this study, survival and development of main stems of Scots pine (Pinus sylvestris L.) following point cleaning were examined in a mixed stand of mainly Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Sweden. Treatments studied were: no precommercial thinning, conventional precommercial thinning, point cleaning of all secondary stems, and point cleaning of only the secondary stems that were higher than the main stem, within a radius of 0.8 m from the main stem, respectively. A randomised complete block design with three replicates was used. Measurements taken 13 growing seasons after these treatments showed that conventional precommercial thinning was the best treatment for retaining Scots pines as main stems. However, conventional precommercial thinning resulted in the poorest timber quality of the remaining Scots pines in terms of stem taper, thickest branch diameter and relative live crown height. In conclusion, point cleaning has to be followed by a complementary cleaning operation if the objective is to retain Scots pines as main stems in such mixed stands.