杂交相思叶面积回归方程的建立

以6年生的杂交相思(Acacia mangium×A.auriculiformis)成熟叶片为材料,将其叶长、叶宽、叶宽/叶长、叶长×叶宽、叶长×叶长、叶宽×叶宽与实测叶面积进行Pearson相关分析,结果表明各叶形指标与叶面积均显著相关。从中选择3个相关指数较高的叶形指标(叶长×叶宽、叶宽×叶宽、叶宽)进行多形式回归方程的建立,最佳拟合方程均为二次曲线方程。经检验和比较,叶宽×叶宽与叶面积的二次曲线方程(Y2=0.002X^2+1.506X+18.695)的理论值与实测值误差率最小,<±7.00%,能较准确地估算杂交相思的叶面积。     

楸树叶面积与叶形指数的回归分析

本实验采用数码相机拍照,利用CAD．图像处理方法得到楸树叶片的面积,并同时测量叶长、叶宽计算出长宽比、长乘宽,通过逐步回归的方法对与叶面积有关的指标进行筛选。用最后得到的最能反映叶面积的指标长乘宽,建立不同叶形的叶片长乘宽与叶面积的一元线形回归预测模型方程,分别是倒心形Y=0．652x＋16．041,决定系数R2=0．7221,水滴形Y=0．5058x＋112．47,决定系数R2=0．4994,三裂Y=0．3211x＋155．98,决定系数R2=0．6006,分析认为可将叶长乘宽作为重要的叶形指数,进行楸树生长等相关研究。     

杜鹃红山茶叶面积回归方程的建立

以杜鹃红山茶（Camellia azalea）成熟叶片为材料,研究杜鹃红山茶叶长、叶宽、叶长×叶宽与叶面积的关系,结果表明：叶长、叶宽、叶长×叶宽与叶面积均呈直线相关,经F检验,差异极显著;所建立的6个回归方程的相关系数高于0.881 488,其中,y=-1 373.824＋22.024x1＋35.583x2为0.956 6、y=-391.205＋12.056x1＋0.361x3为0.952 2。所建立的6个回归方程均可应用于杜鹃红山茶叶面积的测算。     

板栗叶形特征值及其相关性研究

对5个板栗品种叶长、叶宽、叶面积、叶形指数等性状的分析,表明叶形指数稳定性强,能较准确地反映不同品种的叶形特征。叶长、叶宽、叶长×叶定与叶面积存在着极显著的正相关,但以叶长×叶宽与叶面积的相关性最强,其相应的回归方程用于叶面积的测定更为精确。魁栗、紫油光、上光栗、本地土板栗4个品种可共用1个方程（x为叶长×叶宽）进行叶面积测定。     

长果安息香夏季光合蒸腾日变化与其环境因子的关系

长果安息香是稀有濒危植物,国家II级保护植物。为探明长果安息香光合蒸腾特性与其环境因子的关系,在夏季晴朗天气下,利用Li-6400光合测定仪测定了4年生长果安息香的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs,X1)、气温(Ta,Xs)、光合有效辐射(PAR,X3)、空气相对湿度(RH,X4)、大气CO2浓度(Ca,X5)以及胞间CO2浓度(Ci,X6)的日进程。结果表明:长果安息香Pn与Tr日进程曲线均呈"双峰型",有明显的光合"午休"现象,且主要是由于气孔限制因素引起的;水分利用率(WUE)在早、晚较高并在中午出现一次回升;应用逐步多元回归的方法得到了长果安息香的Pn和Tr日变化的最优方程:Y(Pn)=32.719+0.001X3+5.554X1-0.058X5-0.251X2(复相关系数R=0.681,F=44.204,P0.01,标准估计误差Se=0.942);Y(Tr)=4.613+12.353X1-0.057X4-0.002X6(复相关系数R=0.913,F=341.779,P0.01,标准估计误差Se=0.287)。通径分析结果表明,PAR、Gs、Ca、Ta与长果安息香Pn的日变化呈极显著或显著的相关关系,是长果安息香Pn的主要影响因子,直接效应的顺序为CaTaPARGs,总效应顺序为TaCaGsPAR;Gs、RH、Ci是长果安息香Tr的主要影响因子,直接效应和总效应的顺序均为GsRHCi。     

浙江楠苗期生长和光合特性研究

对浙江楠在南京地区的苗期生长特性和光合特性进行了研究。研究结果表明: (1)浙江楠苗期生长呈现指数生长规律,第1a生长较慢,从第2a起呈现加速生长趋势。浙江楠苗期高生长、地径生长和根系生长的指数函数分别是Y=7 106 2e1 058 4X(R2 =0 960 8),Y=15 841e0 452 1X(R2 =0 998 0),Y=0 254 6e0 600 9X(R2 =0 989 4); (2)浙江楠幼苗主根明显,侧根不发达,表现出深根性树种的早期特性; (3)浙江楠苗期表现出一定的喜光特性, 3年生浙江楠的光饱和点约为1 200μmol·m-2·s-1,光补偿点约为20μmol·m-2·s-1。     

基于像素法的Lotos亚属睡莲叶面积回归方程

为寻求便捷地测定Lotos亚属睡莲叶面积的方法,以柔毛齿叶睡莲不同发育时期的叶片为材料,采用直尺测量和数码相机拍照采集原始数据,运用Photoshop软件测定叶面积,建立其叶长、叶宽及叶长×叶宽与叶面积的回归方程,并进行检验及筛选。结果表明:Lotos亚属睡莲叶片形状和尺寸随叶序有较大变化,但叶长、叶宽、叶长×叶宽与叶面积之间均具有极显著的相关性;叶长×叶宽对叶面积的线性方程拟合效果最好,叶宽的二次、三次方程次之,叶长的二次、三次、四次方程再稍次。这6个方程均可较好准确地测算Lotos亚属睡莲,且相互之间无显著差异。     

八角叶面积野外速测

对八角（Illicium verum)叶长、叶宽、叶面积的测定，经回归分析，八角叶片面积与叶长、叶宽、长宽乘积呈直线关系，与长宽乘积最显著。     

橡胶树实生苗生长与叶片性状关联分析

以橡胶树GT1自然授粉种子播种的1年生实生苗为试材,按速生型和一般型2类,对其生长及叶片性状进行测定及相关性分析。结果表明,橡胶树速生型资源苗高和地径均为一般型的1.34倍;所测指标仅叶长、叶宽、叶面积及叶脉密度等4个叶片性状两种类型植株间无交叉,且速生型叶长、叶宽、叶面积及叶脉密度分别为一般型的1.53、1.34、2.00及0.61倍。经相关性分析,苗高和地径均与叶长、叶宽及叶面积呈极显著正相关,与叶脉密度呈极显著负相关,而与叶脉数、叶柄长/叶长、脉左宽/叶宽及比叶面积相关性不明显。综上,橡胶树速生型资源较一般型资源具有较大的叶面积、叶脉分布更稀朗,这是影响其植株生长快慢的主要原因之一。     

豫西黄土丘陵区仁用杏叶片及果实生长发育规律

为了解仁用杏在河南省豫西黄土丘陵区的生长发育规律,并为仁用杏的栽培提供参考,选择"超仁"为研究对象,对仁用杏的叶片及果实生长发育动态进行调查研究,并对其生长曲线进行了拟合,结果表明:叶片长、宽均有2个生长高峰,分别同时出现在4月7日和4月23日,叶片长、宽的生长曲线分别为:Y长=1.219 936+0.355 524 t+0.009 224 t2-0.000 657 t3,R2=0.996;Y宽=0.645 753+0.339 478 4 t+0.002 657 t2-0.000 376 t3,R2=0.995 8.叶面积有4个生长高峰,分别出现在4月7日、4月17日、4月23日和4月27日,叶片的持续增长时间为47天,叶面积生长曲线为:Y面积=0.651 282-0.580 78 t+0.220 554 t2-0.005 732 t2·R2=0.983 2.果实纵、横径的生长发育可分为两个时期,即果实迅速生长期——膨大期历时30 d,果实缓慢生长期——硬核期历时60 d,纵横径的生长曲线分别为:Y纵=0.505 135+0.770 411 t-0.071 88 t<'2>+0.002 195 t3,R2=0.994 8;Y横=0.788 61+0.633 315 t-0.049 635 t2+0.001 346 t3,R2=0.993 1.     

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.     

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.     

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.     

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.     

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.