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。     

酸性土壤上不同钙肥及用量对柚木苗生长的影响

为确定酸性土壤上柚木适宜的钙源肥料及用量,采用裂区设计,分别在广西酸性赤红壤和紫色土上,开展了3种钙肥和4个钙量的柚木苗期大田施肥试验。结果表明:施肥6个月时,两种土类上不同钙肥和钙量处理对柚木苗高和地径影响显著。酸性赤红壤上,氧化钙是促进柚木苗高和地径生长的有益钙肥,其次为硝酸钙,最差为硫酸钙,株施566g氧化钙的苗高和地径的生长量最大,分别比对照提高了27.7%和22.6%。酸性紫色土上,硝酸钙是促进柚木苗高和地径生长的有益钙肥,其次为氧化钙,最差为硫酸钙,株施2 240g硝酸钙的苗高和地径的生长量最大,分别比对照提高了25.7%和14.2%。酸性赤红壤较酸性紫色土更适合柚木的生长,此类土壤上培育柚木,应适量增加钙的施入,以氧化钙为钙源肥料,避免使用硫酸钙。     

不同基质配方对柚木组培苗移植效果的影响

以柚木无根组培瓶苗为扦插移植材料,选用了5种育苗基质,各设4个水平,按照正交实验设计L16(45),开展了不同基质配比对快速培育柚木无性系苗效果的研究。结果显示:采用轻基质+育苗穴盘进行柚木无根组培瓶苗移植,生根容易,成活率高达98.7%;各轻基质配比处理间,除了成活率没有显著差异外,苗高、地径、叶幅、苗鲜质量、苗干质量、根长和主根条数都达到极显著差异,各指标最佳处理分别是最低处理的2.19、1.73、2.20、9.10、7.19、1.82和2.38倍;蛭石不同水平对成活率有显著差异,泥炭土、蛭石、椰糠和黄心土不同水平对苗高有极显著差异;5种基质不同水平对鲜质量、干质量和主根条数都有极显著差异,对根长有显著或极显著差异;对成活率影响最大的是珍珠岩,对苗高、地径和叶幅影响最大的是椰糠,对鲜质量、干质量、根长和主根条数影响最大的是黄心土。以泥炭土︰蛭石︰珍珠岩︰椰糠︰黄心土=1~2︰1︰1︰2︰2为柚木无根组培瓶苗快速育苗的最佳轻基质配比。     

N、P、K对杉木幼苗生长量的影响

开展了施用N、P、K肥对杉木幼苗期生长量影响的研究。结果表明:施肥能显著促进杉木幼苗苗高和地径的生长,但需N、P、K肥配合施,单施N肥的效果较N、P、K配施的效果差,单施N肥和N、P、K肥配施的处理间达到极显著差异。不同施肥处理对杉木苗木的苗高和地径生长的影响也达到极显著差异。此试验最为合理的施肥配方是:N 1.5 g、P 5 g、K 1.5 g,苗高比对照高出38.8%,地径比对照高出46%,可在生产中推广使用。表现最差的施肥配方是N 1.5 g,苗高比对照高出17.4%,地径比对照高出20.0%。     

肯氏南洋杉苗期施肥效应的研究

针对肯氏南洋杉苗期生长缓慢的问题,采用正交试验设计L9(34),通过植物生长所需要的大量营养元素N、P、K 3因素3水平及其不同配比的施肥试验,分析了各元素及其水平对肯氏南洋杉苗高和地径生长的影响,确定了肯氏南洋杉苗期生长的最佳施肥方案。结果表明:1~8个月不同处理间都呈极显著差异,低水平的营养元素对促进肯氏南洋杉苗高和地径的生长好于高水平,以处理1即N1P1K1为施肥效果最好,且与其它处理呈极显著差异;对肯氏南洋杉苗高生长的影响为NPK,对肯氏南洋杉地径生长的影响为PKN。     

不同施肥处理对美国红橡木幼苗生长的影响

对红橡木幼苗进行了不同施肥处理试验,结果表明:施肥显著促进红橡木苗高和地径生长.不同处理比较,T4处理(基质拌入1%NPK复合肥)最好,其苗高、地径均较大,分别比对照高39.3%和33.3%,T1(N肥)处理次之,其苗高、地径比对照高28.6%和27.4%.不同施肥处理对红橡木苗高和地径生长的影响效应从大到小的顺序为:...     

氮素指数施肥对赤皮青冈苗期生长的影响

【目的】指数施肥能诱导苗木对养分的奢侈消耗并建立养分库,从而实现苗木对肥料的稳定持续吸收,进而实现养分在体内的稳定积累,针对1年生赤皮青冈幼苗对不同水平指数施肥的响应,对比常规施肥,旨在探索不同施肥方式和施肥水平对赤皮青冈在不同时间段苗木生长阶段的生长速率大小以及苗木质量指标的影响,揭示指数施肥对赤皮青冈苗木生长的潜在影响以及赤皮青冈苗期对氮素的需肥规律,为赤皮青冈苗木培育和人工林培育提供理论支撑。【方法】以赤皮青冈1年生幼苗为研究对象,采用盆栽试验法,基于对照(CK)、常规施肥(CF)、指数施肥(EF1、EF2、EF3、EF4)等6个处理,施氮量(纯氮)分别采用0、3.0、1.0、2.0、3.0、5.0 g·株-1,分5次施入,每30天施入1次,施肥前先测量苗高、地径,生长期结束后,用全量收获法测定每1株的苗高、地径、干质量。用单因素方差分析法进行生长指标分析。【结果】在不同处理条件下,施氮处理对苗高、地径等影响不同,赤皮青冈的苗高生长差异表现较大,表现为EF2 EF1 CF EF3 EF4 CK,其中处理EF2的苗高达136.5 cm,比对照处理95.2 cm高出43.41%,比常规施肥CF处理高出25.34%,差异均达到显著性水平(P 0.05)。对地径的影响差异表现为EF2 EF1 EF3 CF EF4 CK,其中中低浓度的指数施肥EF2和EF1处理,对地径生长的促进作用显著高于其他处理(P 0.05),地径分别比对照处理高出49.33%、37.38%;中高浓度的指数施肥处理EF3、EF4与常规施肥处理CF对地径生长的促进作用效果相同,也显著高于对照处理。由不同处理条件下赤皮青冈苗木总生物量介于58.13～125.80 g·株-1,不同处理间差异显著,质量指数差别较大(P 0.05),其中以处理EF2、EF1最佳。【结论】指数施肥不仅能节约肥料的施用量,减少肥料的浪费,还能有效提高赤皮青冈苗木质量。综合分析不同施肥方式和施肥量,指数施肥方式EF2处理(2 g·株-1)指数施肥处理在苗高、地径、总生物量、质量指数等指标显著优于1 g·株-1的处理及其他处理,在根比重方面也表现略优,从苗木质量培育的角度综合考虑,指数施肥2 g·株-1是赤皮青冈苗木培育的最佳处理,能获得最佳的苗木形态指标和质量指标。     

施肥对杉木幼苗生长量的影响

对杉木幼苗进行N、P、K配合施肥试验。结果表明:施肥能显著促进杉木幼苗苗高和地径的生长,单施N肥的效果较N、P、K配合施肥的效果差;施肥对杉木苗苗高和地径生长的影响达极显著,单施N肥的处理与N、P、K配合施肥的处理间差异达极显著;最适合的配方是N1.5 g/株、P5 g/株、K1.5 g/株,该处理的苗高比对照高38.8%,地径比对照高46%;效果最差的配方是N1.5 g/株,该处理的苗高比对照高17.4%,地径比对照高20.0%。     

杉木扦插苗不同部位营养元素含量及其分配规律的研究

对1年生杉木扦插苗根、茎、叶中8种营养元素含量的分析结果表明:8种营养元素含量在杉木扦插苗的不同部位差异极显著,不同部位比较N、P、Mn、Zn含量以叶中最高,而K、Ca、Mg、Cu以根中最高,叶中营养元素含量变异系数相对较小。无性系间各营养元素含量及部位与无性系交互作用差异均达极显著水平。N、Mg含量与苗高、地径呈显著相关。     

生长激素处理薄壳山核桃容器苗生长效应初探

试验用不同质量浓度GA3和PP333溶液分别喷施薄壳山核桃容器苗叶面,用不同质量浓度GA3溶液涂抹薄壳山核桃容器苗茎基部;同时在薄壳山核桃容器苗生长旺季初期分3个时期摘心进行对比试验。结果表明,叶面喷施不同质量浓度GA3溶液能显著促进薄壳山核桃苗高生长,但对增粗生长无影响。不同溶度GA3溶液涂抹薄壳山核桃容器苗茎基部、不同质量浓度PP333溶液喷施薄壳山核桃容器苗叶面及不同时期摘心处理都能显著促进薄壳山核桃苗的增粗生长。GA3茎基部涂抹处理相比对照地径增粗26.90%~76.55%,PP333处理相比对照地径增加21.70%~66.04%,摘心处理地径增粗仅为3.79%~23.48%。600 mg/L的GA3溶液涂抹茎基部对薄壳山核桃容器苗生长发育效果最好,300 mg/L的PP333溶液喷施叶面能有效促进薄壳山核桃容器苗增粗,比对照地径分别增粗71.12%和66.04%。     

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.     

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.     

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。