甘肃白龙江林区森林病虫害发生原因及防治对策

本文介绍了甘肃省白龙江林区森林病虫害发生的特点和原因,对云杉落针病、云杉叶锈病、落叶松落叶病;、狭冠网蝽、苗圃地下害虫、蛀干害虫、森林鼠害等主要病虫害的发生动态及原因进行了分析,并提出了综合防治对策。     

白龙江、洮河水源涵养林区云杉落针病危险性分析评估

云杉落针病是白龙江、洮河水源涵养林区最为严重的林木叶部病害。为加强对该病的管理,有效控制其危害和在白龙江、洮河水源涵养林区乃至整个西北地区进一步扩散蔓延,参照有害生物危险性分析(Pest Risk Analysis)方法,结合该区森林资源状况和病虫害发生发展情况,对云杉落针病在白龙江、洮河水源涵养林区的潜在风险性进行了分析和评价。结果表明:云杉落针病为中度危险且接近高度危险性病害。并提出了相应的风险管理策略。     

白龙江林区人工造林适宜树种选择研究

通过对比分析白龙江林区沙滩林场天保工程中所造人工林生长状况,对白龙江林区人工造林适宜树种选择进行研究,结果表明:白龙江林区海拔1 800~2 800m营造针叶树种时应选择细叶云杉和粗枝云杉,海拔1 800m以下宜选择油松;阔叶树种中应选择山杨与其他树种混交造林,以增强林内生物多样性;选用灌木造林时,应以柽柳、中国沙棘为主,同时配置其他树种。     

云杉落针病害调查

云杉落针病害调查＊孙国忠（四川省森林病虫防治检疫总站）杨庆和赵谦王祖成（凉山州林业局）杨学成王瑛（九寨沟自然保护管理处）云杉落针病（Ｌｏｐｈｏｄｅｒｍｉｕｍｐｉｃｅａｅ）是云杉人工幼林的主要病害。我省西部高山林区,１９９０年以前人工更新的２５万公顷云...     

云杉赤落叶病发生规律与危害的研究

云杉(Picea asperata Mast.)分布于四川的岷江、大小金川和白龙江流域,延伸到青海东部,甘肃南部和陕西西南部.处大江大河上游,对森林的水源涵养、水土保持、稳定流量等均具有重要作用.也是高山林区主要用材树种之一.近年来云杉受到30多种病虫害为害,其中主要病害为云杉赤落叶病(Hypoderma sp.).云杉赤落叶病分布范围广,危害严重,造成经济损失很大.在四川阿坝州、凉山州、甘孜州的马尔康、松潘、黑水、金川、木里、丹巴、壤塘均有分布.林木受害株率高达100%,感病指数高达81.8,平均每公顷损失木材幼龄林为5.9833—9.6069米~3.主要危害粗枝云杉     

控制云杉落针病的技术要点

控制云杉落针病的技术要点孙国忠（四川省森林病虫防治检疫总站云杉落针病（Ｌｏｐｈｏｄｅｒｍｉｕｍｐｉｃｅａｅ）是我省川西高山林区云杉人工更新幼林的严重病害。病害的流行区,属高山暗针叶林带。山高坡陡,人烟稀少,交通不便。防治工作必须根据病害的监测结果、林...     

天西林区雪岭云杉天然林病虫害种类

雪岭云杉是天山西部林区的主要树种,为了解雪岭云杉天然林内病虫害的发生情况,以制定相应的防治措施,我们在该林区作了有关调查,具体结果如下:1调查对象调查林分主要在新源林场、特克斯林场、尼勒克林场、察布查尔林场的雪岭云杉天然林及小部分成林的更新地,调查林木的病虫种类、危害程度及部位。2调查结果2.1病虫数量据调查,雪岭云杉林内,对林木造成危害的病虫共有17种,其中病害9种,虫害8种。2.2病害种类(1)雪枯病LophophacidiumhyperboreumLeg-erb.(2)云杉立枯病Rhizoctoniasolanikuhn(3)云杉叶锈病ChrysomyxaweiriiJackson(4)云杉锈病Chrysomyxadeformans(Diet)jacz(5)云杉落针病LophodermiumfiliformeDark(6)云杉稠李球果锈病Thekopsoraareolata(Fr.)Magn(7)云杉腐烂病CytosporaabietisSacc(8)云杉根腐病Armillarellamellea(Vahl.exFr)karst.(9)云杉芽枯病MegaolsemirabilisNaumov2.3虫害种...     

云杉落针病防治的研究

云杉落针病防治的研究孙国忠（四川省森林病虫防治检疫总站）王志平（夹金山林业局）杨庆和（凉山州林业局）杨学成王瑛（九寨沟自然保护管理处云杉落针病（Ｌｏｐｈｏｄｅｒｍｉｕｍｐｉｃｅａｅ）是我省西部高山林区云杉人工更新幼林的重要病害。据１９９０年不完全统计...     

云杉落针与主要因子的相关性分析

在白龙江林区沙滩、茶岗、腊子口、益哇等四个林场的人工云杉林内，设立了45块标准地，对云杉落叶针病的发病程度及有关因子进行了调查，并用数量化理论I和多元线性回归进行了相关分析研究。发现影响该病病毒指数的主要因子依次为林龄、郁闭度、密度、坡向、海拔、披度6个因子；同时建立了病情指数预测模型：（1）Yi=6.194X11 1.474X12 2.664X2 0.88X3 42.024X4 0.010X5 0.167X6-87.898；（2）Yi=3.180X1 2.744X2 0.008X3_41.875X4_0.010X5 0.186X6-78.941。可根据人工云杉林的林分、立地因子调查情况，由模式型（1）或（2）预测落针病的发生趋势。     

白龙江林区人工云杉群体对环境因子的反应

通过多对多数量化回归和双重筛选逐步回归分析，将白龙江林区各种条件下云杉人工群体的生长对环境因子的反应进行定量分析和研究，并对林分平均胸径，平均冠幅，树高，胸径近５年的生长量进行预估，为今后工程化培育云杉人工林提供科学依据。     

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.     

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.     

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.     

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。     

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.     

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.