昆明地区华山松球蚜发生规律研究

１９８９年３月～１９９２年８月工嵩明县大吸及白邑两乡的５～７年生华山松幼林内设立标准地１０块、结合室内饲养，观察华山松球蚜的发生规律及各环境因子对基人种群消长的影响。结果是：华山松球蚜在昆明地区１年发生８代，２月上蟾当日均温达到８℃左右时越冬雌成虫开始产卵繁殖，１１月，当日无温降至５℃以下时雌虫停止产卵，雌成虫分别３月中旬、５月下旬、１０月中旬出现３次产卵高峰，降雨强度、天敌是影响林间球蚜种群种的     

竹箩舟蛾的研究

竹箩舟蛾是竹子的重要食叶害虫,分布于我国南方产竹各省,在浙江省１ａ３～４代,均以蛹于土表下越冬。成虫发生期分别为４月上旬～５月上旬、６月上旬～７月上旬、７月下旬～８月下旬、９月下旬～１０月中旬。幼虫危害期分别为４月下旬～６月中旬、６月中旬～８月上旬、８月中旬～１０月上旬,以第３代蛹越冬者幼虫可延至１０月下旬,第４代为１０月中旬、１１月下旬。第３代幼虫各龄食叶量分别为１．５７、７．７３、１６．３６、５７．０２、５７９．７８ｃｍ＾２,幼虫期共取食竹叶６６２．４６ｃｍ＾２。雌性幼虫期食叶量比雄性多１２％～１５％,每头成虫产卵量为１６１～２８６粒。天敌有赤眼蜂、黑卵峰、姬蜂、寄蝇等。并提出了相应的防治方法。     

国槐双棘长蠹生物学特性及防治的研究

作者于１９９４～１９９８年研究表明，双棘长蠹是石家庄市的一个新害虫，仅危害国槐细枝干，１年发生１代，每代有４个虫态。成虫期近１０个月，卵期５～８ｄ，幼虫期３０～４０ｄ，蛹期７ｄ左右。４月中旬～５月上旬是成虫产卵、蛀食危害盛期，１０月上旬～１１月中旬新成虫开始迁移、蛀食危害、越冬。幼虫、新成虫具有群居和固守的习性。依据这些生物学特性，提出了加强检疫、清理受害枝以消灭越冬成虫、幼虫、新成虫的无公害新防治策略，并收到了显著效果。     

榆举肢透翅蛾的研究

榆举肢透翅蛾是导致榆树间接死亡的钻蛀性害早。在兰州地区两年发生一代，以幼虫在虫道越冬，老熟幼虫在丝质茧内化蛹，５月中，下旬－７月焉旬或８月上旬为蛹发生期，６月中旬－８月中，下旬为成虫发生期，６月下旬－８月下旬为卵发生期，７月上旬始见初孵幼虫，１０月上旬幼虫越冬。     

日本锤角叶蜂的研究

日本锤角叶蜂Ｃｉｍｂｅｘ ｊａｐｏｎｉｃａ Ｋｉｒｂｙ是近年来在中国山西中部出现的一种为害榆树的新害虫,曾造成了严重灾害。此虫１年发生１代,以老熟幼虫做茧,在枯枝落叶或２￣３ｃｍ深疏松土中越冬。雌虫行弧雌生殖,单头产卵量５０粒左右。成虫发生高峰期在５月上旬。幼虫为害榆树高峰期在５月中旬至６月中旬。防治关键时期一是４月中旬成虫羽化前,可于树冠下挖茧,集中烧毁;二是５月中旬幼虫孵化盛期,可喷功夫３００     

华竹毒蛾生物学特性及防治方法的初步研究

华竹毒蛾是毛竹的食叶害虫，在安福武功山区一年发生３代，以蛹在竹杆上的地面灌木杂草叶背越冬，翌年４月中旬开始羽化产卵。１、２、３代幼虫发生危害期分别为：４月下旬－６月下旬，７月上旬－８月上旬，８月中旬－１０月中旬。以第２代发生整齐且危害最烈。在幼虫１－３龄期用ＤＤＶＰ插和烟雾剂进行熏杀，效果可达８０％，蛹期寄生虫较多，可利用于防治。     

萧氏松茎象生物学特性及其防治研究

萧氏松茎象是严重蛀食国外松主干基部皮层的新害虫。该在江西吉安等地两年发生一代,以幼虫和成虫越冬。越冬成虫３月中下旬出忌化孔活动,４月下旬开始产卵,５月中旬开始孵化为幼虫,当年１２月上旬幼虫越冬,至翌年３月中旬越冬幼虫复苏,８月中旬开始化蛹,９月中旬开始羽经为成虫并在蛹室内越冬。     

栗绛蚧寄生蜂生物学特性观察

栗绛蚧的寄生蜂有８种，６种育自雌蚧，１种育自雄蚧，１咱育自雌蚧及雄蚧。每年发生１代，营内寄生，寄生雌蚧的蜂种。发生期集中于３月中旬至５月中旬，林间成蜂有三个羽化期，３月中旬至４月上旬，４月中旬至下旬，５月中旬。林间寄生率３．２％～６２．７％。     

草履蚧的生活史及赵冬卵在土壤中的分布调查

草履蚧在陕西１年发生１代,一般情况下越冬卵 孵化盛期为２月中下旬,若虫２月中旬至３上旬上树危害,雌成虫４月下旬至６月中旬下树,下树雌虫在树干周围的地面杂物下、土缝、疏松土层内产卵越夏和过冬。蚧虫卵在树完下土壤中的分布规律、分布量与距树干的距离远近有关,集中分布于距离树干６０ｃｍ范围内地面以下－～５．６～１０ｃｍ的土层中。以土壤中草履蚧的卵量作为该虫的防治指标时,指标值确定为树冠下在离树干６０ｃｍ范     

栗绛蚧寄生蜂生物学特性观察

栗绛蚧ＫｅｒｍｅｓｎａｗａｉＫｕｗａｎａ的寄生蜂有８种：６种育自雌蚧，１种育自雄蚧，１种育自雌蚧及雄蚧。每年发生１代，营内寄生，寄生雌蚧的蜂种。发生期集中于３月中旬至５月中旬，林间成蜂有三个羽化期，３月中旬至４月上旬，４月中旬至下旬，５月中旬。林间寄生率３．２％～６２．７％。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

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.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

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.     

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.     

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.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

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.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

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.     

CAD与建筑设计的关系

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。