国家核查组核查全区农村沼气工作

9月26—29日，由国家农业部发展计划司副司长郭红宇带队的国家农村沼气调查核查组到广西核查2003—2010年农村沼气工程建设和使用情况。自治区林业厅副厅长邓建华、副巡视员肖超陪同核查。郭红宇副司长表示：“广西沼气建设在全国属于领先水平，     

高效能源型:开辟广西沼气发展的广阔空间

沼气的发展方向:从替代薪柴型转向替代液化气天然气型"十一五"期末,广西全区农村五年新增沼气用户106万个,全区沼气池入户率提高到46.4——这两个响当当的数据,充分展现了广西农村沼气建设事业的辉煌成就。今年5月28日至6月4日,由自     

技术和创新:农村沼气可持续发展的关键

抽样调查显示,广西农村户用沼气使用率呈现逐年下降的趋势。2007年全区沼气池正常使用率85%,半停半用率11%;2009年正常使用率82%,半停半用率14.3%;2010年正常使用率80.9%,半停半用率15.8%。为此,最近记者采访了广西林业科学研究院农村能源研究所所长李金怀教授。记者:您认为导致农村沼气使用率逐年下降的原因有哪些?李金怀:近年来,农村沼气的发展进入了一个低谷期,不单是     

广西获2012年中央农村沼气项目资金2亿多元

2012年8月1日，广西获2012年中央农村沼气项目资金2．0543亿元。在2亿多元项目资金中，包括户用沼气投资17660万元，用于博白、埔北等98个县8．83万户农村户用沼气池建设；养殖小区和联户沼气投资579万元，用在富川、融水等4个县建设养殖小区和联户沼气工程214处，大中型沼气工程项目资金1107万元，用在广西玉林市博白县文地镇青河村大中猪场等10个大中型沼气工程建设；乡村服务网点投资1197万元，用在宾阳、西乡塘区等62个县建设农村沼气乡村服务网点266个。     

试论桂林市沼气建设的综合效应

桂林市的农村沼气建设始于20世纪70年代，到了80年代初，恭城县将农村沼气建设作为县、乡党委政府的主要工作来抓，经过十多年的艰苦探索，逐步形成了“猪沼果”的生态农业模式。1996年桂林开始总结学习“三位一体”的恭城经验，1997年在广西全面推广。近几年，桂林市的各级党委、政府非常重视农村沼气建设，把以沼气     

林业简讯

危朝安唐仁健提出农村沼气建设新要求 2014年6月20日、7月1日，自治区党委常委、副书记危朝安，自治区党委常委、副主席唐仁建分别在林业厅报送的广西农村沼气项目建设使用情况调研报告上作出重要批示。     

科学规范推进农村沼气项目建设

2008年12月23日,自治区林业局在田阳县召开深入学习实践科学发展观快速推进新增项目暨沼气生态家园建设工作会议。会议贯彻落实党的十七届三中全会精神和党中央、国务院关于进一步扩大内需、促进经济增长的战略部署,2008年中央新增投资1000亿中安排了30亿用于农村沼气建设,其中国家安排给广西的农村沼气建设投资为16034万元。     

自主创新攻克沼气池进料难题

近年来，沼气池特别是户用沼气池建设数量大增，一些缺乏常规沼气发酵原料的农户也建上了沼气池。为了取得沼气，农村沼气用户尝试着用蚕粪、杂草、树叶、作物秸秆等（以下称“植物性沼气发酵原料”）作为沼气发酵原料投入沼气池，但人工进料较困难。为此，一些秸秆型沼气池用人工配合机械进料，但这一种较简单方便的进料办法管理成本较高，难以在户用沼气池中推广使用。为解决植物性沼气发酵原料进料难的问题，广西蒙山县农村能源办公室自主创新、研制一种简单实用、使用成本低的进料省力装置，在户用沼气池中推广使用很有实际价值。     

论发展怒江州农村沼气的可持续性

以云南怒江州农村沼气可持续发展为切入点，分析了促进农村沼气可持续发展的重要意义，结合该州当前农村沼气发展现状，探讨了沼气发展中存在的突出问题，并提出了一系列旨在促进农村沼气可持续发展的对策。     

桂林沼气富农家

在广西桂林市林业局采访,听得最多的不是造林绿化,更不是木材生产,而是全社会动员大办沼气。市林业局局长李开生提供了这样一组数字:一个8立方米的沼气池,每年产沼气400立方米,基本满足了农村一个五口之家的生活用能问题。市政府投巨资帮助漓江两岸的农户建沼气池,六年累计建池1.4万多座,沼气入户率达到80%以上,每年为农户提供沼气500万立方米,沼肥18万吨,解决了两岸大部分农户的生活用能问题,从根本上保护了漓江两岸的森林植被,保护了漓江两岸的秀美风光。以沼气和煤电代柴的农村能源结构和燃烧方式的变革,每年可节约柴草180万立方米,相当…     

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.