黄河三角洲盐碱地白蜡“3414”肥效试验研究

采用"3414"田间试验方案,对黄河三角洲地区滨海盐碱地3年生白蜡进行了连续2年的氮、磷、钾田间肥效研究。结果表明,不同肥料配比对白蜡的生长产生了显著影响,所有施肥处理白蜡苗木的胸径增长率显著高于对照处理,当N、P2O5和K2O的施用量分别为0.064kg株-1 a-1、0.036kg株-1 a-1和0.048kg株-1 a-1时,白蜡的胸径的当年、累积增产率以及经济效益均优于其它施肥组合。通过拟合所得的一元二次施肥效应模型计算得出,在本试验条件下白蜡的N、P2O5和K2O最佳经济效益施肥量分别为0.070kg株-1 a-1,0.047kg株-1 a-1和0.068kg株-1 a-1。     

核桃“3414”肥料效应试验及推荐施肥量的回归分析

为了探寻最适养分施用量和最佳施肥方案,从而提高核桃产量和培肥土壤,为核桃生产中的科学施肥提供技术指导,以陕西省黄龙县栽培的‘香玲’核桃树为试验材料,采用"3414"试验设计进行了施肥效应试验,并结合试验田的基础地力水平,采用两种方法对核桃产量与肥料用量之间的关系进行了回归分析,得出了N、P2O5、K2O这3种肥料的最佳用量。结果表明:不同的施肥量对核桃产量的影响很大,缺肥或少肥都会影响核桃产量,与对照相比各施肥处理的核桃产量均有提高,其中处理6(N2P2K2)的产量最高;而且,在这3种肥料的互作效应中,N、P、K的互作效应最高,其次为N与K、N与P、P与K的互作效应。由回归方程计算得出的N、P2O5、K2O的最高施用量分别为1.009 1、0.190 4、1.227 6 kg·株-1,最佳施用量分别为0.987 5、0.1648、1.226 0 kg·株-1,最高和最佳产量分别为8.373、8.368 kg·株-1。N、P2O5、K2O含量与产量的一元二次拟合方程的拟合程度均较好(R2值均较大),但在此3种养分施用量与产量的一元二次效应方程的相关关系中,N、P2O5、K2O都没有达到显著水平。以两种拟合方程计算得到的结果相近,考虑到既要高产又能培肥土壤的目的,该研究以采用三元二次效应方程拟合的养分推荐施用量作为核桃试验地施肥的标准用量。     

尾叶桉无性系施肥6年的生长效应

尾叶桉无性系施肥6年试验结果表明：施肥对尾叶桉无性系具有显著的增产效益和经济效益。不同施肥处理的尾叶桉无性系生长的差异极显著，而所有施肥处理的生长均极显著大于对照。最佳的施肥处理为每公顷施N75kg,P2O5200kg和K2O50kg，最佳的施肥配比，N，P，K的比例为1.5:4.1，其6年生平均树高，胸径和蓄积生长量分别为16.02m,11.45cm和121.8m^3/hm^2。比不施肥（对照）分别增加23%，61%和175%，比施肥量最大的处理分别增加7.50%，14.04%和40.97%。最佳施肥处理的经济效益也极显著，6年生砍伐获纯利为6432.95元/hm^2。投入与产出比为1：2.23。内部收益率为21.4%；其所获纯利分别是不施肥处理和施肥量最大处理的15.14倍和2.51倍。     

沸石与N、P、K、Ca不同配比对柚木幼林早期生长的影响

为研究沸石与N、P、K和Ca配比对柚木幼林早期生长的影响,采用裂区设计,沸石为主区,以N、P、K和石灰为4个因素,各个因素3水平,正交设计L_9(3~4)的通过9个施肥处理为副区,进行施肥试验。结果表明:造林后18个月,沸石处理间柚木树高生长差异显著,施用沸石显著提高柚木高生长;施肥处理间树高和胸径生长差异极显著,最佳施肥为处理4(N2P1K2Ca3),即每公顷施N 200 kg、P 300 kg和K 200 kg以及每株施石灰1 kg,其柚木树高和胸径分别是最差处理的1.66和2.07倍;4个因素不同水平间主要以P三水平(100、200、300 kg/hm~2)间差异极显著,高P水平(300 kg/hm~2)柚木树高和胸径生长分别是低P水平(100 kg/hm~2)的1.51和1.61倍。P施肥对柚木早期生长影响效果极显著,而K肥对霜冻后的柚木生长恢复影响显著。     

不同营养条件对黎蒴栲苗木形态指标的影响

采用均匀设计对黎蒴栲实生幼苗进行不同梯度的N、P、K配比施肥试验,探讨不同营养条件对黎蒴栲幼苗苗高、地径、冠幅的影响。结果表明：1）不同营养条件对黎蒴栲幼苗的形态指标有很明显的影响。T5（N：0.075 0 g/株、P2O5：0.350 0 g/株）施肥处理的苗高、地径、冠幅较大,其次为T4（N：0.112 5 g/株、K2O：0.050 0 g/株）、T3（P2O5：0.175 0 g/株、K2O：0.100 0 g/株）施肥处理,T1（N：0.150 0 g/株、P2O5：0.262 5 g/株、K2O：0.150 0 g/株）、T2（N：0.037 5 g/株、P2O5：0.087 5 g/株、K2O：0.200 0 g/株）施肥处理和对照则较差。2）N、P、K对黎蒴栲幼苗生长的影响效应各不相同。氮肥可促进黎蒴栲幼苗的生长,但过多的钾肥则不利于黎蒴栲幼苗的生长。     

不同营养条件对黎蒴栲幼苗形态指标的影响

采用均匀设计对黎蒴栲实生幼苗进行不同梯度的N、P、K配比施肥试验,探讨不同营养条件对黎蒴栲幼苗苗高、地径、冠幅的影响。结果表明:1)不同营养条件对黎蒴栲幼苗的形态指标有很明显的影响。T5(N:0.075 0 g/株、P2O5:0.350 0 g/株)施肥处理的苗高、地径、冠幅较大,其次为T4(N:0.112 5 g/株、K2O:0.050 0 g/株)、T3(P2O5:0.175 0 g/株、K2O:0.100 0 g/株)施肥处理,T1(N:0.150 0 g/株、P2O5:0.262 5 g/株、K2O:0.150 0 g/株)、T2(N:0.037 5 g/株、P2O5:0.087 5 g/株、K2O:0.200 0 g/株)施肥处理和对照则较差。2)N、P、K对黎蒴栲幼苗生长的影响效应各不相同。氮肥可促进黎蒴栲幼苗的生长,但过多的钾肥则不利于黎蒴栲幼苗的生长。     

配方施肥对毛竹林新竹生长及经济效益的影响

通过"3414"施肥试验,研究了不同N、P、K配方施肥对福建三明毛竹林新竹生长及竹林经济产出的影响。结果表明,N、P、K不同配方对新竹的成竹率、新竹胸径与新竹产量以及对竹林经济产出的影响差异显著。14个配方处理中,N2P3K2的新竹数最高,为对照的1.69倍;N2P2K2的新竹胸径和产量均为最大,分别为对照的1.09和1.91倍,且新竹叶片的N、P、K、Mg浓度最为均衡。该试验条件下,施尿素540 kg/hm2、硫酸钾135 kg/hm2、过磷酸钙450~675 kg/hm2,能较为有效地促进新竹生长与产量持续。各配方施肥对毛竹林的增产幅度为18.1%~192.4%,增产效益明显,N2P2K2的竹林产值最高,是对照的2.92倍,资金产出率(产投比)前3位为N2P2K2、N2P3K2和N2P2K3,分别是3.83,3.43和3.26,N素对新竹生长的影响最大,缺N素、P素试验的资金产出率低于无施肥处理。     

乐东拟单性木兰幼林营养需求特性研究

按正交表L9(34)排列的N、P、K三因素三水平的施肥试验表明:乐东拟单性木兰幼林对肥料反应相当敏感,正交试验9个处理中,以N1P1K1为对照,N1P2K2、N1P3K3、N2P1K2、N2P2K3、N2P3K1、N3P1K3、N3P2K1、N3P3K28个处理使得树高生长增加了7.1%～35.7%,胸径生长增加了9.6%～51.4%,施肥效果最好的处理是N2P3K1,即50g/株尿素、200g/株钙镁磷肥;营养元素N、P、K三要素中,P是主要因子,其次是N,最后是K;乐东拟单性木兰幼林应多施磷肥,但从经济性考虑100g/株钙镁磷肥已足够;同时应施少量的氮肥,即50g/株尿素;不必施钾肥。     

配方施肥对沙县毛竹林新竹生长效应分析

通过N,P,K 3因素3水平的正交施肥试验,分析了不同N,P,K肥配施对福建省沙县毛竹林新竹生长的影响。结果表明,一定施用量范围内的N,P,K肥组合在不同程度上影响着毛竹林新竹的生长,9个施肥处理与对照(未施肥)比较,各处理之间除新竹胸径差异不显著以外,新竹竹高、株数、产量均达差异显著或极显著水平,其中N3P1K3(尿素1 050 kg/hm~2,过磷酸钙900 kg/hm~2,硫酸钾300 kg/hm~2)的新竹胸径生长达最大(10.8 cm),比对照增长14.9%;N3P3K2(尿素1 050 kg/hm~2,过磷酸钙1 350 kg/hm~2,硫酸钾150 kg/hm~2)的新竹竹高达最大,比对照增长11.3%;选择施肥后新竹产量作为评价施肥效应的综合指标,极差分析认为,施用均衡且适当的N肥(尿素750 kg/hm~2)、P肥(过磷酸钙900 kg/hm~2)、K肥(硫酸钾150 kg/hm~2),其新竹产量为25.8 t/hm~2,比对照增长79.2%,能为新竹生长提供足够的养分。     

不同栽培措施对尾巨桉生长的影响及经济效益分析

试验采用列区试验设计,设造林密度和追肥2个因素,每个因素6个水平,4次重复.密度因子作主区,追肥因子作副区,各个因素和各处理按随机区组排列.每个试验小区面积0.04 hm2(20 m×20 m),共计144个小区,连续5 a观测.经过方差分析得出,造林试密度对林分平均高、平均胸径和蓄积量都有极显著的影响.在6种参试密度中,造林密度越大,林分平均高、胸径越小,蓄积量越大;6种配方追肥对林分平均高影响不显著,对胸径和蓄积量生长影响显著;密度与追肥的交互作用不显著.在所有36个列区试验组合中,按经济效益排列前5名的密度和追肥最佳组合分别为:2 222株.hm-2和每公顷施N、P、K分别为200、150、100 kg,1 667株.hm-2和每公顷施N、P、K分别为300、200、200 kg;1 667株.hm-2和每公顷施N、P、K分别为200、150、100 kg;2 222株.hm-2和每公顷施N、P、K分别为100、50、50 kg;1 250株.hm-2和每公顷施N、P、K分别为200、150、100 kg.它们的蓄积量分别为183.94、188.43、169.95、164.33、163.03 m3.hm-2;利润值分别为14 977.44、14 965.09、13 832.83、13 785.80和13 345.18元.hm-2.     

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。