基于SPOT-5影像的马尾松毛虫虫害遥感监测研究

马尾松毛虫是马尾松林的主要害虫,危害很大,实施有效监测是对其进行防治的关键。以福建沙县为研究区,以SPOT-5遥感影像为数据源,基于短波红外波段、红光波段和近红外波段等构造归一化植被指数等光谱特性指数,基于灰度共生矩阵法提取均值等影像纹理特征,引入坡度、坡向等地形及林木因子构建马尾松毛虫虫害遥感监测指标,通过岭回归分析建立虫情级数估测模型进而反演,进行虫害监测信息提取,并与单纯基于光谱特性指数指标的虫害信息提取方法进行比较。结果表明:1)综合考虑影像的光谱特性、纹理特征与地形及林木因子影响进行虫害监测,显著增强了虫害的光谱响应能力,相比于单纯基于光谱特性的虫害监测信息提取,其总精度提高了14.28%;2)这些为林业生产实践提供技术支撑与理论借鉴,同时也在一定程度上推动遥感监测森林病虫害的理论认识与信息提取方法。     

马尾松毛虫成灾之年造成马尾松活立木材积生长量的损失不容低估

一、马尾松毛虫成灾之年马尾松活立木材积生长量明显下降众所周知马尾松毛虫Dendrolimus Punctatus Walrer是我国松林的大害虫,不仅危害面积大,且分布广,几乎有马尾松分布的省区均有不同程度的发生,但每年马尾松毛虫猖獗成灾之年,人们可见松林针叶被吃光如同火烧状,严重被害枯死的植株,人们砍伐就易于统计损失量,而受灾未死的活立木,究竟影响材积生长量多少?就不易     

思茅松毛虫防治的试验

中方县现有马尾松林面积11103公顷,为我县的主要绿化用材树种。自20世纪90年代以来,我县对马尾松毛虫进行了综合治理,马尾松毛虫的发生危害得到了有效的控制。近几年来,思茅松毛虫在我县的局部松林呈块状分布,主要危害马尾松林,其食量比马尾松毛虫更大,局部发生区危害较重时出现了针叶稀疏、光干现象,林相从远处看就象被火烧过一样,严重影响树木的生长。为此,我们采用两种农药对其进行防治试验。     

飞机低容量喷雾防治马尾松毛虫

马尾松毛虫是危害松林最严重的历史性害虫。主要危害马尾松 ,猖獗时还可危害湿地松、火炬松、黑松、雪松等松林。马鞍山森林公园位于武汉市东南近郊 ,山林主要树种为马尾松 ,历年不同程度的遭到马尾松毛虫的侵袭。其幼虫食害松树针叶 ,受害严重的松林针叶常被吃光 ,仅留枝梗 ,状如火烧 ,枯黄一片 ,被人们称为不冒烟的森林火灾。 1995年森林公园开幕时 ,第一代马尾松毛虫大发生 ,凤凰亭台、鸽楼、路上、松树上都有许多幼虫爬行 ,树上的幼虫弹跳于游客身上 ,由于幼虫体被毒毛 ,人体暴露部位常引起皮炎、关节肿局部症状 ,少数人还有畏寒、低热…     

马尾松尺■生活及生活习性的初步观察和防治试验

一、分布及危害马尾松尺 (Abraxax sp)是马尾松林的一个主要害虫。以幼虫期进行危害,症状似松毛虫危害状,严重时可将大面积的针叶吃光。其危害盛期,正是马尾松抽生长时期,所以对林木生长影响极大,连年受害可造成林木死亡。     

四川马尾松林区主要松毛虫改称油松毛虫的研究

马尾松是四川主要用材树种之一,分布在四川盆地及其盆地边缘地带。历年各地马尾松林均在不同程度上遭到松毛虫的危害,大发生的年份,其受灾面积可达100万亩左右,松毛虫是我省林业上的大害虫。过去,主要根据松毛虫种类与寄主的相关性〔2〕、〔4〕,认为马尾松林区的松毛虫种类是马尾松毛虫(Dendrolimus punctatus Walker)。但近年在四川却发现油松毛虫(D.tabulaeformis Tsai et Liu)主要危害马尾松〔13〕。〔14〕,因而,对四川马尾忪林区松毛虫的种类及其分布,在1979—1980年开展了调查研究,现报告如下。     

平岗低丘马尾松林经营指数研究

本研究通过对不同树种，不同混交比及不同覆盖率的松林内马尾松毛虫发生危害情况的调查资料进行综合分析，提出了抑制马尾松毛虫灾害的松林经营最佳指数为０．２－０．４。     

不同程度马尾松毛虫危害对松林植被群落的影响

采用样点调查法对不同程度马尾松毛虫危害松林的植被群落进行了调查。结果表明:不同程度马尾松毛虫危害对松林林分密度的影响不显著,但对松树生长量有着不同程度的影响,中、重度危害可降低松树的高度和胸径(重度危害三年后高度、胸径分别下降0.34 m和1.8 cm),轻度危害则可促进松林的生长;马尾松毛虫危害可适度改变松林的郁闭度和地表植被的盖度(中、重度危害后三年盖度分别上升15%和20%),对林下植被的恢复与生长有一定的促进作用;松林植被物种多样性分析表明,中、重度马尾松毛虫危害可有效增加林地植被物种的多样性,轻度危害则对林地植被物种多样性影响不大。     

取食不同受害程度的马尾松对马尾松毛虫种群数量的影响

利用不同受害程度的马尾松Pinus massoniana针叶饲养马尾松毛虫Dendrolimus punctatus，研究其对马尾松毛虫生长发育的影响.结果表明：马尾松毛虫取食不同受害程度松针后，幼虫的取食量、排粪量、蛹重、对食物的消耗和利用指数、化蛹率、生殖力、发育历期和死亡率均有所不同，其中幼虫的取食量、排粪量、蛹重、对食物的消耗和利用指数、化蛹率和生殖力以取食未受害松树（针叶损失0）的最高，重度受害（针叶损失75%）次之，轻度受害（针叶损失25%）再次，中度危害（针叶损失50%）最低，而发育历期和死亡率则相反，由此可见马尾松毛虫取食不同受害程度的松针对其种群数量有明显的影响。     

马尾松用材林3—4代类型区松毛虫防治指标的研究

通过对3—4代类型区马尾松毛虫室内外取食及为害针叶量、松树针叶蓄积量和人工模拟虫害对松树材积生长影响进行测定、研究分析的基础上,提出了该类地区马尾松用材林松毛虫防治指标。试验表明,因虫灾引起松林失叶25％时,一般情况下不必防治;失叶50％以上时,要根据害虫数量、林分状况及天敌对害虫控制能力等进行综合评断。防治指标与松树年龄的幂回归关系为 y=1.4903·x~(1.1688)。     

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.