恩施地区杉木地位指数表的编制

<正> 地位指数是一种表示立地质量的数量指标。是以标准年龄为准,用林分平均优势木高来反映立地条件的。可用于评定立地质量,预测林分生长,检验经营效果。杉木是恩施地区重要的速生用材树种之一。解放以来,杉木栽培面积不断增加,栽培范围不断扩大。全区杉木林基地面积已达两百余万亩。为了适应我区用材林基地建设的需要;为评定杉木立地条件,制定合理的经营措施;给森林调查规划设计提供科学依据,1981年     

杉木良种幼林期生长动态对比分析

对福建省将乐国有林场在不同立地条件下营建的8个杉木良种对比试验林,分析其3～11年生时的生长差异性。结果表明:品种间生长性状在各林龄差异均达到极显著水平,而品种与立地的交互作用同样显著影响着生长性状,特别是在7年生前其作用较品种的影响作用更明显,之后2种影响作用在11年生时逐渐达到平衡。11年生时,品种对树高、胸径和单株立木材积的方差贡献率分别为25.67%、17.59%和20.80%,品种与立地交互作用对树高、胸径和单株立木材积的方差贡献率分别为28.23%、16.48%和17.31%。以单株立木材积为主要指标,筛选出洋003无性系、官庄2代种子园良种为广谱适宜速生品种;Ⅲ类立地最适宜速生品种为官庄2代种子园良种,Ⅱ～Ⅲ类立地和Ⅰ～Ⅱ类立地最适宜速生品种为洋003无性系。7年生时有的品种的林分内已经产生株间竞争,并首先明显作用于胸径,致使单株间胸径差异加大,进而逐步影响单株立木材积,可进行初次抚育间伐。     

杉木速生优良无性系选育

在杉木优良种源的基础上,选育出一批杉木速生优良无性系。通过13 a的研究表明,各无性系间胸径、树高、单株材积差异极显著,且具有较大的广义遗传力。根据杉木无性系培育目标,选育出18个杉木速生优良无性系,入选12 a生无性系的平均树高、胸径和单株材积分别为11．03 m、16．98 cm和0．135 6 m3,与对照相比,树高、胸径和单株材积的遗传增益依次为10．71％、37.97％和113．08％;现实增益分别为14．25％、47．61％和140．01％。     

杉木45个无性系在种子园抗炭疽病的调查

本文是对靖县排牙山林场杉木嫁接种子园炭疽病自然发病情况的调查报告。用1977—1982年的调查结果,按各无性系的平均感染指数大小分类,将杉木45个无性系划分为抗病(X)。属于抗病的有5个无性系,占45个无性系的11.11%;中庸的22个,占48.89%;感病的18个,占40%。以10、Ⅲ和20号无性系最抗病,即使进行人工接种也不发病。尤其是20号无性系,是属于生长快(>X S)的一类,但结实少(<(?))。20号家系的子代也表现较好,其速生抗病的优良性状较稳定,可作为建立高一级种子园和杂交组合的材料。     

江西省杉木人工林合理轮伐期的研究

根据江西省高丘陵区、山区和南岭山地3个杉木栽培区的生长特点,不同立地不同培育目标有不同的成熟龄,而当立地条件和培育目标相同时,3个栽培区的成熟龄差异不磊,可以按统一的轮伐期经营。12指数级培育小径材为主的轮伐期为18～22年,14指数级培育小径材轮伐期为16～20年,16指数级培育中径材轮伐期为20～24年,18指数级培育中径材轮伐期为14～18年,18指数级培育大径材轮伐期为24～28年,20指数级培育大径材轮伐期为22～26年。     

杉木嫁接种子园炭疽病的发生和防治

靖县排牙山林场,于1973年春,用45个无性系建立17亩杉木嫁接种子园。该园位于平缓阳坡上,坡度为10—15度。立地条件中等。母岩为砂质岩,土壤为山地黄壤。砧木为四年生实生杉木,平均地径5厘米。1～46号无性系的接穗采自靖县大堡子公社;Ⅰ—Ⅲ号无性系的接穗采自排     

不同立地条件及施肥措施对造林的影响

经国务院批准，林业部决定：从1990年开始，引进世界银行贷款资金，发展速生丰产用材林基地，以扩大森林资源，缓解木材供求矛盾，靖州被列为项目县之一。为了确保项目的顺利完成，促进科技兴林，提高营林生产技术和管理水平，保证世行造林的质量和成果，我们着重从营林生产技术措施方面，如何提高林木速生丰产，就不同的立地条件及施肥措施进行了试验和研究。通过几年的试验，示范和观察测定，取得了明显的社会效益、经济效益和生态效益。1材料与方法参试树种为杉木、湿地松、马尾松；选择立地指数为14、16、18三种地位指数级进行对比试验…     

杉木无性系造林对比试验及重复力估测

引进浙江省12个杉木无性系扦插苗在Ⅱ、Ⅲ类立地的不同坡位上与福建省大田桃源国有林场初级种子园实生苗进行造林对比试验.结果表明,20 a生时12个无性系间在树高、胸径、冠幅、单株平均材积生长上均存在极显著差异,枝下高因造林密度原因差异不显著;不同坡位造林对无性系的影响,除冠幅显著外,其它各生长性状均极显著;与实生苗对比,适宜本地发展的杉木无性系首选57号、28号,其次为38号、A1、110号,可作为建立采穗圃的优良种源.无性系各生长性状重复力测算结果表明,20 a生时各无性系与原株之间的遗传特性保持极高的稳定性.     

杉木无性系选择与生长潜力分析

在湖南会同县、绥宁县以33个杉木无性系和2个对照分别于1983年、1986年及1997年营造了单株、行状和块状3种造林形式的区组设计无性系试验林。研究发现参试无性系间胸径、树高生长量的差异在幼林期(4—7年)、中林期(13—16年)和成林期(28—31年)始终显著存在。不同无性系生长规律不同,有的无性系幼林期生长不是特别突出,但在中林期生长加快,到中林期后趋于稳定。优良无性系y18、y15在28或31年生时仍能保持前期所具有的生长优势,且在16 m立地指数和18 m立地指数条件下,生长同样突出,排名均为1、2名,表明这2个优良无性系的生长量具有一定的时间和空间稳定性。在块状造林条件下,优良无性系13年生时树高、胸径生长量和单位面积蓄积量分别大于生产种20.1%26.6%、27%31.1%、78.7%92.8%,表明发展杉木优良无性系造林可获得巨大的经济效益。     

黔杉1号～4号杉木良种选育

为选育优质速生杉木繁殖材料,扩大杉木遗传改良遗传基础,1992年在黎平县营建了多父本杂交试验测定林,通过子代测定和区域测试,评选的4个最优家系命名为黔杉1号、黔杉2号、黔杉3号、黔杉4号,通过了贵州省林木品种委员会审定。应用黔杉1号~4号杉木良种苗木在贵州杉木中心产区立地指数16以上的立地造林,材积遗传增益分别比优良种源、优良半同胞家系和初级种子园提高37.1%、12.0%、29.6%。     

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。