黑枣苗氮磷营养及经济施肥的研究

试验采用苗床施肥，结果表明，肥料用量适宜促进营养元素吸收利用，７～８月份苗木叶片含氮量３．５％～４．０％、含磷量０．２％～０．３％、含钾量１．０％或稍高时，苗木生长良好。在该试验条件下，施Ｐ２Ｏ５１２０ｋｇ／ｈａ、施纯氮１８０ｋｇ／ｈａ左右，幼苗产量、质量及施肥利润均达到较高水平。     

油茶组培苗移栽及施肥试验

通过油茶组培苗移栽基质、时间和施肥肥料浓度对苗木生长影响的试验,结果表明,组培苗移栽成活率最高的基质是红心土,高达98．26％;但为利于苗木的生长,移栽方式是以先把瓶苗移栽于7cm×11cm的红心土营养杯内培养60d,苗木恢复生长,并长出2～3张叶片时再移栽到9cm×13cm椰康基质营养杯内培养适宜苗木生长,培育120d,苗高9．48cm,比使用红心土的苗高（4．04cm）高134．6％;施肥浓度为1％时,油茶组培苗生长效果良好,培养100d,苗高比施肥前高5．428cm,比对照的高143．8％。     

不同施肥对平榛幼苗生长的影响

为明确不同施肥处理对平榛幼苗生长的影响，以平榛幼苗为研究对象，设计9个不同施肥组合，清水为对照，采用方差分析、多重比较等方法，对不同施肥处理的平榛幼苗进行统计和分析。结果表明：不同施肥处理对平榛幼苗生长和苗木质量有显著地影响。不同处理的平榛幼苗苗高、地径、叶片数、根数、根长均高于对照，以N₂P₂K₃处理的苗木生长指标最优，苗木质量最好。在平榛育苗过程中要科学合理进行施肥，在生长季选用10 g/m施尿素+10 g/m磷酸二氢钾+15 g/m硫酸钾的氮磷钾配比肥进行叶面喷施，促进苗木生长，提升苗木质量。     

樟子松种子园母树施肥效果分析

于１９８４－１９８６年在彰琥县章古台樟子松种子园进行母树施肥试验。试验采用基施肥法，共１２个处理，按各处理混合的化肥，同３００ｋｇ草炭同时施入，以不施草炭和化肥的母树作对照。结果表明，施肥当年促进母树开花效果不明显，第２年则雌球花数量有明显增加，处理（８）、处理（１２）、处理（１１）分别为对照的２．９、２．７和３．３倍，以上各处理的种子产量，分别为对照的２２５．１％、１９４．１％和２３７．９％。施     

大气污染地区火炬松幼林施肥效应*

在四川省大气污染地区的隆昌县境内，１９９０～１９９２年进行了火炬松人工幼林７种（含对照）处理的施肥试验，试验林分６ｈｍ２，观测区１．８ｈｍ２。结果表明，不同施肥处理，在树高、胸径、地径的生长量差异都极显著（α＝０．０１），６种施肥处理中，含Ｐ、Ｃａ、Ｎ元素的肥料配方效果最好，在施肥后的３ａ中，最佳处理比对照树高相对生长量增加８０％～１６６％。施肥处理减缓了火炬松幼林污染危害症状。施肥第二年５月，叶黄化率比对照减轻１３％～６０％，落叶量减少２５％～７７％。     

樟子松苗木沙培试验施肥效应

通过对樟子松沙培施肥的试验，正交方差分析表明不同施肥处理对苗木各指标影响大多不显，并由此建立起樟子松S1－1苗木施肥函数方程。     

大叶栎容器苗育苗期的施肥试验

在大叶栎容器苗的育苗期进行了氮、磷、钾3种元素不同配比的施肥试验,研究不同施肥配比处理对其苗木生长量、叶面积、叶绿素含量、生物量以及苗木质量指数的影响。结果表明:不同配比施肥处理的大叶栎容器苗苗木各项指标均存在显著性差异。氮、磷、钾3种元素的平衡施用对大叶栎容器苗生长的促进作用最大,为最优施肥配比,经过4次施肥后苗木的苗高、地径、叶面积、叶绿素含量、地上干重、地下干重分别是不施肥(对照)的205.2%、122.7%、375.3%、148.3%、240.7%、124.7%。     

指数施肥对杂交新美柳幼苗生长及生物量积累的影响

探明指数施肥对杂交新美柳(Salix matsudana×alba)幼苗生长及生物量的影响，可为其苗木培育提供基础。以1年生杂交新美柳扦插苗为研究对象，采用盆栽试验法，设置对照(CK)、常规施肥(CF)和指数施肥(EF1、EF2、EF3、EF4)共6个处理，每次施肥间隔时间为30天，共施肥5次，每30天对苗木的苗高、地径进行测量，生长结束后，测定生物量。结果表明：不同施肥处理情况下，杂交新美柳的苗高和地径生长差异表现较大，EF2处理的苗高生长量最大，比CF处理高出36.40%;EF1处理的地径生长量最大，比CF处理高出21.63%。EF处理的生物量显著高于CF和CK，其中EF2处理表现最好，全株生物量、地上部分和地下部分生物量与CK处理相比分别增加了96.86%、84.31%和157.60%。综上，指数施肥3.0 g株^-1施氮量和19.99 g株^-1多元复合肥是杂交新美柳1年生培育的适宜施肥方式。     

杨树苗期施肥试验

对长林1号、中黑防、小黑无絮速生杨进行施肥试验,结果表明：最佳施肥方案为速生前期施1/2,速生后期施1/2,施肥量（N：P：K=2.01.00.5）1 500 kg.hm^-2;施肥苗木与对照相比较提前3～7 d封顶,而且木质化程度好,苗木合格率比对照提高11.6%。     

根外施肥技术的研究

经过３年连续对２１种不同施肥配比浓度及不同喷施时间的根外施肥试验，筛选出最佳喷施肥处理：夏季为Ｃ３、Ａ３，其苗高、地径、次年高、地径生长量比对照分别提高３３．９％～３７．１％、８．２％～１８．２％、２９．５％～３１．１％和２３．４％～３１．９％；春、秋季为Ｃ４、Ａ４，苗高、地径生长量较对照提高２９．５％～３１．１％和１２．８％～２７．７％。育苗成本比普通容器育苗提高１．０％～２．０％。试验表明掌握好时机的秋季施肥育苗措施是可行的，同时改变了传统秋季不予施肥的观点。     

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.