柳杉半同胞子代遗传变异与优良遗传型选择

对40个柳杉半同胞子代的生长、木材品质和形质等性状的遗传变异规律和相关性进行了比较系统地研究,结果表明:2年生树高及26年生树高、胸径和材积等生长性状在家系间存在显著差异;木材品质和形质性状中的髓心偏心率和木材心材比率在家系间存在显著差异,而树皮率和木材基本密度在家系间的差异不明显;2年生树高与26年生胸径、材积间呈显著正相关,心材比率与26年生树高、胸径和材积间呈显著正相关;树皮率与2年生树高相关性不明显,而与26年生树高、胸径和材积等呈显著负相关;髓心偏心率、木材基本密度与生长性状相关性不明显。通过综合比较,评选出生长量大、木材品质好的优良家系12个,树高、胸径和材积的平均遗传增益分别为1.21%、4.77%和8.02%,木材偏心率的平均值为0.3%,木材基本密度的平均值为0.341 g/m3,这些优良家系具有广阔的推广应用前景。     

长白落叶松优良家系选择的研究

对黑龙江省宁安县省林科院所属的江山娇实验林场23年生长白落叶松自由授粉家系子代测定林的研究结果表明,树高、胸径、材积都存在较大的变异,9年生变异系数分别为5.5%、8.2%、18.0%;23年生变异系数分别为12.0%、18.0%、38.9%.家系间变异幅度树高、胸径及材积分别为7.9%～14.2%、12.6%～21.9%、28.0%～45.2%.树高、胸径、材积3个性状在家系间都存在显著差异,23年生时树高、胸径、材积的家系遗传力分别为0.696、0.492、0.608,生长性状受中等强度的遗传控制.通过对17个家系的生长性状分析,筛选出了226、96、251三个生长性状优良的家系.     

火炬松引种家系遗传变异及速生家系选择

对10年生火炬松半同胞家系的生长性状测定表明:火炬松的树高、胸径和材积在家系间差异显著,火炬松家系的生长形状主要受中等遗传力所控制,参试家系性状在各试验点的变异系数差异明显,材积的变异系数在7.90%～17.13%。通过育种值法最终筛选出5、16、18、6和8号等5个速生家系。     

巨桉引种试验及优良遗传型选择

对8年生巨桉种源、家系试验林进行全面调查分析表明：生长性状在不同种源、家系间存在显著或极显著差异;形质性状在不同种源间差异不显著,在不同家系间存在极显著差异;耐寒能力在不同种源间存在极显著差异,在不同家系间差并不显著。通过综合评价和比较,选出适应福建省永安地区种植的巨按优良家系10个,树高、胸径、材积和耐寒指数平均值分别为14．80m、16．6om、0．1749m^3和4．42,树高、胸径和材积的遗传增益分别为18．96％、加．44％、67．17％;优良个体15株,其树高、胸径、材积和耐寒指数平均值分别为17．91m、20．63cm、0．2976m^3和4．85,树高、胸径和材积的遗传增益分别为44．9％、48．8％和184．1％。这些优良材料可以通过无性繁殖进行推广应用。     

杉木第二代种子园子代遗传变异及优良家系选择研究

来自广东省龙山林场杉木第二代种子园的39个自由授粉家系参加了1998年多点子代测定和2001年单点子代测定试验,结果表明：11年生子代测定林的树高、胸径、单株材积在家系和地点间差异达到极显著水平（P〈0．01）,8年生子代测定林生长性状的差异较小;家系平均树高、胸径、材积遗传力分别为0．24、0．26、0．30,主要生长性状受中等偏下的遗传力控制;第二代种子园材积遗传增益在1．88％～5．85％．其遗传增益和现实增产效果高于1．5代种子园,也高于初级种子园。对11年生多点子代测定林家系进行了丰产稳定性分析,选择出广谱丰产稳定家系5、8、17、19、23、26、28号,平均单株材积比群体均值提高3．39％;丰产家系3、7、15、21号和家系20、22、25号,分别适合龙山林场和曲江林场及相似立地条件地区限制性推广利用,平均单株材积比群体均值分别提高9．91％和4．89％;8年生单点子代测定林,以单株材积高于群体均值作为入选标准,有1、2、4、6、7、8、10、11、12、14、15、19等12个家系入选,平均单株材积比群体均值提高6．76％。     

长白落叶松优良家系选择的研究

对24年生长白落叶松自由授粉家系子代测定林的研究结果表明，胸径、树高、材积3个性状在家系间都存在显著差异，通过对17个家系的生长性状分析，筛选出了170、120、501、322、153、274六个生长性状优良的家系，其胸径、树高、材积平均大于对照3．83％、7．23％、11．67％。     

Productivitv evaluation and family selection of 25-year old plus tree progeny in Pinus massoniana

对25年生马尾松优树子代测定林调查分析,结果表明马尾松子代树高、胸径、材积在家系间存在显著的遗传变异,其家系遗传力分别为0.428、0.565和0.610.利用以树高、胸径、材积构建的指数选择方程从参试家系中选择出20个速生优良家系,平均材积遗传增益为26.0％.从入选的优良家系中选择出100株优良单株,平均材积比群体均值大122.21％.     

邓恩桉生长、木材密度和树皮厚度的遗传变异研究

以广西桂林和柳州的邓恩桉种源/家系(6个种源53个家系)试验林为材料,对8.5年生胸径以及10.5年生胸径、树高、材积、木材密度和树皮厚度的遗传变异进行了研究,结果表明:10.5年生时,邓恩桉在桂林和柳州的平均单株材积分别为0.218、0.189 m~3,平均木材密度分别为521.0、483.7 kg·m~3,树皮厚度分别为1.15、1.26 cm;10.5年生材积性状和木材密度在种源间差异不显著(P＞0.10),10.5年生木材密度在家系间差异显著(P＜0.05);树皮厚度在种源间、家系间差异均不显著(P＞0.10).除8.5年生胸径外,其他性状的试验地点与种源间交互作用不显著(P＞0.10);8.5年生胸径、10.5年生树高、木材密度均存在显著的试验地点与家系间交互作用(P＜0.05);10.5年生树皮厚在种源、家系水平上和地点均不存在显著的交互作用.8.5年生胸径、10.5年生胸径与树高的遗传力在0.128 9～0.234 5间,木材密度的遗传力为0.700 0～0.962 9,树皮厚度的遗传力为0.105 3～0.335 7.     

龙泉杉木三代种子园子代林主要生长性状变异研究

对营造在浙江省龙泉市林科院6年生杉木三代种子园家系(36个家系,1个对照)子代林的树高、胸径和材积进行测定与分析.结果表明:6年生杉木的树高、胸径和材积3个生长性状在家系间差异达极显著,且有相对较高的广义遗传力,而材积有中等以上的遗传变异系数.杉木三代种子园有较好的群体改良效果,6年生时材积的遗传增益比对照提高了14.89％.以材积为依据,采用对比法选择出9个早期速生型杉木优良家系,其群体的树高、胸径和材积平均值分别大于对照10.04％、15.99％和45.69％.     

高脂马尾松扦插苗与实生苗造林早期生长比较

通过对高脂马尾松扦插苗、实生苗进行造林试验，结果表明：造林后2～5年，两种林分平均保存率均达到95％以上；3、4年生时树高、胸径、单株材积差异极显著，4年生时扦插苗的幼林树高、胸径、冠幅、单株材积平均分别高于同龄实生苗的13．11％、24．95％、18．53％和69．81％，说明利用优良无性系繁殖扦插苗进行造林是可行的。     

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.     

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。     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.     

Key Habitats in the Norwegian Production Forest: A Case Study

This study investigated the forest history, structural characteristics, the presence of fungal species suggested to indicate ecological continuity in old-growth forest, and the species composition of saproxylic beetles in 30 old forest ''woodland key habitats'' (WKHs), and compared them with production forest in the same age-class in south-eastern Norway. No statistically significant differences in forest characteristics, community of saproxylic beetles or number of red-listed beetles were found between the WKHs and the production forest, probably owing to a combination of profound long-term logging and a lack of will to delineate sufficiently large WKHs in the one area with significantly less forestry impact. The study indicates the advantage of including forest history information in WKH selection where such data exist, and the importance of restoring habitats in heavily exploited forest landscapes.