广西资源县林下种植箬竹试验

采用正交试验设计法,研究不同树种、不同上层树木郁闭度及不同施肥量对林下箬竹生长的影响,探讨林下大面积种植箬竹的可能性。结果表明,不同上层树木种类对箬竹生长的影响差异不显著;箬竹秆高生长在较大郁闭度(0.6～0.7)下表现最好,叶片生长在中等郁闭度(0.4～0.5)下表现最好,而地径生长则在低郁闭度(0.2～0.3)下表现最好,因此可根据箬竹具体经营目的调整上层林分的郁闭度;施肥能明显促进箬竹秆高、地径及叶片生长,施肥量越大对箬竹生长的促进作用越大。研究结果可为定向培育箬竹秆用林、叶用林或秆叶两用林提供科学依据。     

毛竹林郁闭度对林下套种草珊瑚生长的影响

对毛竹林不同郁闭度林下套种草珊瑚的当年成活率、枝高生长、萌发的枝条数及种植第三年草珊瑚保存率、枝高生长和生物量(植株鲜重)进行调查分析,结果表明:毛竹林不同郁闭度林下套种草植珊瑚当年成活率影响不显著,当年草珊瑚枝高生长、萌发的枝条数影响极显著;种植第三年草珊瑚保存率、枝高生长及生物量(植株鲜重)影响极显著。另外,在毛竹林郁闭度0.6~0.7林下套种草珊瑚生长好、保存率最高、生物量最大、经济效益最好。     

杉木林下套种华山姜生长情况研究

在0.4、0.6、0.8等3种不同郁闭度的杉木林下套种华山姜,观测其株高、萌蘖能力、根茎鲜重等指标,研究华山姜的叶面积、叶长、叶宽、比叶面积(SLA)的差异。结果表明:套种当年华山姜在不同郁闭度杉木的林冠下成活率均为100%,在郁闭度为0.8林下华山姜长势最好;5 a华山姜在保留郁闭度0.6的杉木林下萌蘖能力、产果量、姜产量最佳,各项观测指标在不同郁闭度之间存在显著或极显著差异;不同郁闭度林下华山姜叶面积、叶长、叶宽、比叶面积(SLA)存在显著差异,郁闭度0.6林下华山姜叶片生产力最高,适应力更强。建议杉木林下套种华山姜适宜在郁闭度0.6的林下进行。     

竹林套种竹荪生态栽培技术研究与效益评价

试验研究了不同竹林郁闭度(郁闭度分别为0.6、0.7、0.8和0.9)、竹荪品种(长裙竹荪D89和D1)和竹林类型(散生竹和丛生竹)对林下竹荪生长及经济效益的影响。结果表明:竹林郁闭度对林下竹荪生长的影响极为显著,以郁闭度为0.7的竹林竹荪生长最好,出荪期达2个多月,产量达41.0 kg/667 m²,净利润为9 120元/667 m²;竹林套种不同品种的竹荪其产量和经济效益差异不明显;不同类型的竹林对于竹荪产量及经济效益的影响也不明显。因此,竹林适宜于套种竹荪,同时竹林套种竹荪还可带来减少环境污染、增加就业岗位以及促进竹林可持续经营等多重效益。     

杉木林林分郁闭度对南方红豆杉幼树生长的影响

不同的杉木林郁闭度对在其林下套种的南方红豆杉的造林成活率、树高、胸径、冠幅生长都有显著影响。郁闭度为0．45～0．55时,南方红豆杉造林成活率最高,幼树长势也最好。     

泉州森林公园林下栀子生长和开花特性

为丰富泉州森林公园林下观赏植物,在园内开展不同郁闭度乔木林下栀子的生长和开花特性研究。结果表明,栀子在林下种植的成活率达90%以上,栀子苗高生长随上层乔木林郁闭度的增大而降低;冠层郁闭度对林下栀子花期产生影响,过度郁闭的林分会使林下栀子花期缩短;林下栀子的正常花数和开花率均表现为随着上层林冠郁闭度的增大而减少,而栀子的未开花数随着上层林冠郁闭度的增大而增大。     

杜茎山扦插繁殖与栽培技术研究

采用不同扦插基质、不同扦插时间对杜茎山进行扦插繁殖试验,并在不同郁闭度环境下对杜茎山进行栽培试验,结果显示：以100％黄土做扦插基质,其扦插成活率最高,平均成活率达95％;50％营养土＋50％黄土次之,其平均成活率为85％;50％细沙＋50％营养土最差,其平均成活率仅为70％。扦插时间以10月扦插成活率较高,达94．5％;6月扦插成活率较低,为85％。杜茎山在郁闭度0．6～0．7的林下平均高88cm,平均地径0．423cm,生长较好;在郁闭度0．9的林下平均高仅22．5cm,平均地径仅0．33cm。     

擎天树裸根苗移栽试验研究

从叶片处理、林分郁闭度、移栽时间3个方面,探讨了擎天树(Parashorea chinensis)裸根幼苗移栽成活的影响因素,并进一步研究了移栽后苗木生长量与郁闭度、移栽时间的关系。结果表明,不同处理方法对擎天树幼苗的移栽成活率和生长的影响存在显著差异。剪切50%叶面积的幼苗成活率显著高于不剪切的;郁闭度为0.4的林下移栽,擎天树幼苗成活率最高,生长量指标也最好;5月移栽的幼苗成活率最高,但3月移栽的幼苗苗高和根系生长最好。通过叶片剪切、林分郁闭度、移栽时间处理,有效调控适宜擎天树苗木移栽和生长的水分、温度和光照。     

桉树林下套种草珊瑚栽培技术研究

本试验采用L9(34)正交试验设计法,探讨不同桉树林郁闭度、不同种植坡向及不同追肥种类对林下草珊瑚生长发育及产量的影响。试验结果表明:郁闭度是影响桉树林下套种草珊瑚的关键因素,郁闭度0.7最适宜草珊瑚生长发育,且产量最高;种植坡向对草珊瑚的高生长影响较明显,而对产量影响不大,南坡最适宜草珊瑚种植;种植后的追肥种类对林下套种草珊瑚影响不大,结合生产实际,建议最好是采用无机肥与有机肥结合施用,以达最佳效果。     

滨海前沿木麻黄林下更新试验

在滨海前沿木麻黄基干林带下的树种更新试验结果表明,不同树种的适应性差异显著,湿地松较木麻黄稍耐荫些,乌墨的长势最差,客土量大小对林下树种生长无显著影响;林带郁闭度对林分高、径生长有显著或极显著影响,随着郁闭度增大,林分生长量逐渐下降,林内树木生长显著低于皆伐更新林分;林下木麻黄、湿地松树高生长与林带郁闭度之间呈线性相关。     

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.     

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.     

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。     

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.