茂县辐射松引种造林试验研究

经过连续多年采用不同的整地方式、不同造林密度、不同覆盖保水对辐射松(Pinus radiataD.Don)造林及幼林生长的试验研究,结果表明:(1)干旱地带采用水平沟、短册状整地比穴状整地造林成活率提高2.4~7.8个百分点,保存率提高1.0~7.6个百分点,高生长量提高7.8 cm~28.4 cm,地径生长量提高0.28 cm~0.84 cm。(2)水平沟整地比短册状、穴状整地0~100 cm土壤层含水量全年分别提高1.29个百分点和2.08个百分点,旱季分别提高1.36个百分点和1.37个百分点,雨季分别提高1.16个百分点和2.87个百分点;短册状整地比穴状整地0~100 cm土壤层含水量全年提高0.80个百分点,旱季提高0.01个百分点,雨季提高1.72个百分点。(3)采用1.5 m×2.0 m造林密度,短册状或水平沟整地,采用石块、塑料薄膜覆盖,造林成活率达96%,保存率达90%。     

宁南山区坡地改造工程土壤水分动态研究

通过对宁夏南部山区在退耕还林工程中，不同立地类型采用不同方式的造林整地的土壤水分监测，得出：88542水平沟整地对不同坡位和100cm土层内不同层次的土壤含水量均有不同程度的影响，水平沟整地土壤含水量均比自然坡面高。     

提高荒山雨季造林成活率的主要措施

<正>1做好栽前准备工作1.1选好山坡,合理整地根据实际情况合理整地,一般是上年雨季整地,次年造林,也可春季整地雨季造林或雨季随整地随造林。整地时,按照水土保持的要求,尽量减少破土面。一般对山坡上部及25°坡以上的地段,采用穴状、鱼鳞坑整地。穴径30~40cm,深20~40cm;鱼鳞坑长径30~50cm,短径30~40cm,     

岷江上游干旱河谷辐射松引种造林研究

经过连续14 a的辐射松(Pinus radiata D.Don)引种造林研究,结果表明(1)采用1.5 m×2.0 m造林密度,短册状或水平沟整地,采用石块、塑料薄膜覆盖,造林成活率达96%,保存率达90%.(2)抚育压青6 a的辐射松幼树树高生长量为对照的2.02倍,地径生长量为对照的2.19倍;每株幼树施20 g(N)+100g(P)施肥量的树高生长量比对照提高65.7 cm～120.2 cm,地径生长量比对照提高1.74 cm～3.83 cm;1/3修枝强度比对照树高生长量提高295.7 cm,地径生长量提高3.0 cm,1/4修枝强度比对照树高提高198.1 cm、地径生长量提高2.54 cm;(3)辐射松1 a中有2次高生长高峰期、3次径生长高峰期,高、径速生期在4～6龄年出现,幼林的根系、枝干、叶的生物量在5 a生时也急剧增加.     

三分式径流增肥整地对黄土丘陵区土壤理化性状和蓄水能力的影响

依托中日合作第二期黄河中游流域防护林建设项目,以昕水河流域的典型地区吉县、大宁、蒲县、隰县4个县为试验点,运用三分式径流增肥整地技术对该地区土壤理化性质、蓄水能力展开了试验研究,结果表明:土壤孔隙状况得到明显改善,10 cm~60 cm土层总孔隙度和毛管孔隙度平均提高了6.4%~7.8%和8.8%~11.2%,特别是0 cm~30 cm土层,与对照相比,孔隙状况得到极大改善;4种三分式径流增肥整地方式0 cm~40 cm土层的有机质、全氮、全磷、全钾及水解氮、有效磷、速效钾均有较大提高,与对照相比分别提高了57.1%,21.21%,17.0%,3.2%,38.1%,51.1%和22.5%;水平沟整地秋季、春季土壤含水率分别比对照高1.1%和1.3%,相对提高了5.7%和13.7%.鱼鳞坑整地秋季、春季土壤含水率分别比对照高1.1%和2.4%,相对提高了5.5%和26.4%.在最干旱的6月份,水平沟整地和鱼鳞坑整地平均土壤含水率分别提高了2.5%和2.4%,相对提高了35.7%和37.5%.     

整地与栽植深度对林木生长量影响的研究

通过整地与栽植深度对林木生物量影响的分析研究,结果表明:大工程穴状整地(穴径100 cm、深60、80、100 cm)较一般小穴整地(穴径30 cm、深30 cm)之5年生林木径生长量分别提高7%、9.7%和11.3%;高生长量分别提高3.4%、7%和9.6%;林木根量可增加78.2%;栽植深度以40~50 cm为宜,这有助于降低生产成本。     

隔坡水平沟土壤水分变化规律及利用效果研究

2003年至2005年对隔坡水平沟土壤水分变化规律及利用效果进行了研究,结果表明:不论年份雨水丰欠,落叶期比栽植期隔坡水平沟0 cm-200 cm土层土壤储水量均有所增加,3 a平均增加91.9 mm,雨季降雨量多的年份水平沟土壤储水量增加幅度相对更大,落叶后水平沟比坡地0 cm-200 cm土层土壤储水量3 a平均高出50.6 mm;在同一年份中,隔坡水平沟核桃的高生长量均高于坡地核桃,3 a平均高生长量比坡地核桃高23.3 cm.     

滨海石质裸露山地造林模式及初步成效

为积累福建省滨海石质裸露山体植被恢复经验,总结了2015年以来莆田市秀屿区石头山复绿工程的主要技术措施,调查分析了鱼鳞坑和石坎水平阶2种整地模式下主要造林树种的生长量、成活率、保存率及土壤水分情况。结果表明:2种模式下苗木地径、树高生长量分别提高了23.5~62.9%、21.2~71.7%;造林成活率、保存率提高了10%以上;0~20 cm表层及20~40 cm深层土壤含水量分别提高了15.2~47.4%、7.3~27.8%。     

鄂尔多斯市东胜区油松造林技术的研究

油松在丘陵区造林,应选择在阴坡的中下部或厚层土立地;采用鱼鳞坑和水平沟整地,比不整地造林成活率分别提高19.6%和34.3%;整地时间应在造林前一年的雨季前;坐水造林成活率比对照提高21.6%;合格苗造林成活率比不合格苗提高47.3%。     

整地深度对土壤物理性质的影响

通过不同整地深度对土壤物理性质的影响研究,结果表明:深整地空白处的土壤含水率较对照空白处提高0.46个百分点;深整地较浅整地土壤垂直温度变化小,在0~70 cm范围内,每深10 cm,浅整地地温下降1.0 ℃,而深整地的下降0.9 ℃;深整地较一般整地土壤容重减小11%,土壤孔隙度增加5.5个百分点。研究结果还表明,适宜的整地深度以50~60 cm为宜,这有助于降低造林成本,提高经济效益。     

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。