集雨托盘在樟子松、云杉等树种抗旱造林中的应用

青海省大部处于干旱、半干旱地区,保持土壤水分、提高树木成活率成为造林关键问题。在樟子松、云杉等树种造林中应用集雨托盘进行抗旱造林对比试验,结果表明:覆盖集雨托盘显著提高了北山林场云杉幼树树高和冠幅的生长及其存活率、高生长率、冠幅生长率;覆盖集雨托盘显著提高了平安县油松幼树当年高生长量及其生长率和存活率;覆盖集雨托盘显著提高了大通县樟子松苗木树高生长量、存活率和高生长率;覆盖集雨托盘显著性提高了都兰县枸杞苗木冠幅生长量,提高了其冠幅生长率和存活率。     

鄂尔多斯地区文冠果大田育苗的影响因素分析

通过文冠果大田育苗的正交试验,分析鄂尔多斯地区对文冠果育苗的几种影响因素。试验结果表明:种子的播种期、覆土厚度、土壤的p H值对文冠果出苗影响较大,在覆膜的情况下,5月中旬播种、覆土3 cm比较合适;贫瘠的土壤上育苗,需要施肥来补充苗木生长所需的养分;对于文冠果成苗来说,有一定的土层厚度才能较好地生长。     

不同抚育措施下4种能源树种生长和坐果率研究

对文冠果、山杏、山桃和柄扁桃等4种能源树种分别在生长季进行了灌溉制度、施肥措施、喷施防落素和在造林时蘸根处理等试验,结果表明：山杏、山桃和柄扁桃的平均株高、平均当年生长量、平均地径、平均分枝数、平均冠幅长和宽等生长特征均是灌溉12次最高,并随着灌溉次数的减少逐步降低;文冠果则是灌溉9次为峰值,并且随着灌溉次数的增多和减少逐步降低。文冠果和柄扁桃以施牛粪最为理想,而山杏和山桃则以施二胺较好。施肥次数方面,文冠果以施肥2次为宜;而山杏、山桃和柄扁桃的各项生长指标表现出施肥3次最好。另外,在造林时对苗木进行蘸根处理可以提高文冠果、山杏、山桃和柄扁桃的生长;在开花期喷施防落素可明显提高文冠果、山杏、山桃和柄扁桃的坐果率,增幅分别为56.06%、50.31%、87.61%和17.37%。     

断胚根处理对文冠果育苗的影响及配套技术研究

研究了断胚根处理对生物质能源树种文冠果种子发芽成苗的影响。通过对不同时期的文冠果种子进行不同程度的断胚根处理,定量分析了文冠果种子断胚根的最佳处理时期,处理方法与再生根的数量、长度、根幅、直径,出苗率,苗高,冠幅的关系,解决了文冠果种子断胚根的关键技术指标和参数,并以此构成较为完备的文冠果育苗配套技术体系。结果表明:文冠果种子萌发期间,进行断胚根处理,可促进侧根增加,胚根长4cm,留根长2cm时,断胚根效果最显著;胚根斜切口处理的新生根数和根长优于平切口;断胚根处理后,文冠果当年生露地苗木的成活率比对照组提高14.16%,苗木平均高增加7.22cm。     

文冠果根系腐烂防治技术研究

以1年生文冠果实生苗为试验材料，在山西省朔州市平鲁区开展了不同土壤消毒处理、苗木根系处理及组合处理对其根系腐烂率及根系生长情况的影响。结果表明，不同土壤消毒处理中，福美双处理文冠果的新根长度显著大于其他处理；不同苗木根系处理对文冠果根系的影响不显著；在组合处理中，福美双+0.5%KMnO₄处理后苗木新根数量显著大于其他组合处理，木霉菌+500倍多菌灵和福美双+500倍多菌灵处理后新根长度显著大于其他组合处理。由不同处理的有效指数可知，用5%的KMnO₄溶液对文冠果根系进行浸泡或用木霉菌与500倍的70%代森锰锌可湿性粉剂溶液分别进行土壤消毒、根系浸泡，能够防治文冠果苗木根系腐烂，促进其断根处新根的萌发和伸长生长。     

5个乡土绿化阔叶树种不同育苗基质的当年育苗效应试验

在昆明树木园所进行的连香树、多果槭、榉树、枫杨和川滇桤木等5个乡土绿化阔叶树种不同育苗基质的当年育苗效应试验的结果表明:在其当年生苗木的苗高、地径和冠幅3个性状上,与对照红壤育苗基质相比,不同育苗基质对此5个乡土绿化阔叶树种当年生苗木的苗高、地径和冠幅生长的作用不一,红壤4+福贝菌2育苗基质(处理A)和(复合肥2 kg+钙镁磷肥2 kg)/100 kg红壤育苗基质(处理C)对5个乡土绿化阔叶树种当年生苗木的生长均具有促进作用,对连香树、多果槭、榉树和川滇桤木等4个阔叶树种的当年生苗木生长具较佳促进作用的育苗基质是处理A,其连香树当年生苗木的苗高、地径和冠幅分别比对照高34.04 %、15.00 %和15.38 %;多果槭当年生苗木的苗高、地径和冠幅分别比对照高70.55 %、23.81 %和39.18 %;榉树当年生苗木的苗高、地径和冠幅分别比对照高31.93 %、35.33 %和33.33 %;川滇桤木当年生苗木的苗高、地径和冠幅分别比对照高101.65 %、38.27 %和50.63 %.而促进枫杨当年生苗木生长的较佳育苗基质是处理C,其当年生苗木的苗高、地径和冠幅分别比对照提高44.30 %、23.55 %和30.93 %.     

磷肥对文冠果苗木生长的影响

文冠果（Xanthoceras sorbifoLia Bunge．）为无患子科冠果属,是我国特有的珍贵木本油料树种。在培育文冠果生物质能源林中,需要用优质的苗木保证培育的成功。在育苗中,磷（P）元素作为植物生长必不可少的大量元素,对培育文冠果优质壮苗具有重要的影响。磷在植物体内以两种状态存在,有机磷和无机磷。     

干旱半干旱地区影响文冠果育苗的主导因子分析

为了探索干旱半干旱地区影响文冠果育苗的主导因素,采用正交试验设计,就播种期、种子等级、覆土厚度、基质类型、营养杯规格等因子对文冠果育苗的影响情况分别进行了大田育苗和容器育苗试验,并通过指标测定和数理统计分析优选出了影响文冠果育苗的主导因子及其处理水平。研究结果表明:影响文冠果育苗的主导因子分别是播种期、种子等级、覆土厚度、基质类型、营养杯规格;5月中旬播种、种子等级为Ⅰ级、覆土厚度为5 cm、基质为牛羊粪+本地土、营养杯规格越大的苗木其长势越好;土壤理化性质对文冠果育苗也有一定的影响,土层厚度与苗高、地径间均呈正相关,其相关系数均在0.95以上,土壤养分是苗木生长所需养分的重要来源,适于其苗木生长的土壤p H值在6.5~8.0之间。     

长兴县香樟残次绿化苗木改造提升技术初探

采用截干修剪的方式对20株大规格(胸径15cm)香樟残次绿化苗木进行为期3年的改造试验,通过分析试验数据可知,改造苗木平均胸径增长量小于未改造苗木,但二者差距随着生长时间逐渐缩小;改造苗木平均树高增长量大于未改造苗木,且第二年较第一年差异达显著水平;改造苗木平均冠幅增长量大于未改造苗木,且二者差距随生长时间持续增大,改造苗木平均冠幅增长量在整个生长时期表现为显著性差异水平。通过效益分析可知,改造苗木与未改造苗木每亩效益差距达2.75倍,香樟残次绿化苗木改造的效益巨大,可根据全县实际情况逐步推广。     

文冠果根系调查研究

文冠果(Xanthoceras sorbifolia Bunge)是开发、栽培历史较短的油料树种。70年代以来,内蒙古农牧学院研究了文冠果根系的组成和生长动态。缨礼科等调查过文冠果苗木的根系。周君英等进行了切除根尖,促生侧根的试验。而有关文冠果根系的生长特性、生态因子同根系生长关系的研究,未见报道。为此,我们于1981—1982年在内蒙古和林格尔县浑河林场及中国林业科学研究院磴口实验局,对1—16年生文冠果树根系进行了调查研究。     

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.