济源市退耕还林工程的经济和社会效益分析

退耕还林工程是我国为防治水土流失、土地沙化等生态环境恶化问题而采取的一项重大工程,对我国林业建设与生态环境修复起到了巨大的作用。然而,退耕还林工程对经济与社会效益的影响在之前的研究中考虑得较少,该影响的好坏将直接关系到退耕还林工程的顺利实施与发展,特别是农村的可持续发展。采用实地调查和问卷调查相结合的方式,对济源市的退耕还林工程综合效益进行定量评价与定性分析。通过对济源市在退耕还林工程实施前后国民生产总值、粮食产量、农村人均收入、农民就业率、第1、2、3产业的变化的分析和研究,表明退耕还林工程的实施取得了较显著的经济和社会效益。     

普洱市实施退耕还林工程效益分析

退耕还林工程是我国林业建设史上政策性最强、工作程序最多、涉及面最广、投资量最大、群众参与程度最高的生态建设工程之一。普洱市通过实施退耕还林工程,取得了明显的生态、经济和社会三大效益,同时,不同程度的暴露出一些影响退耕还林后续发展的问题,文章对此做了以下分析,以供同行参考。     

多伦县林业建设十年投入资金近6亿元

2000年以来，多伦县抓住连胜实施林业重点工程的机遇，加大林业资金和建设任务争取力度，卓有成效地实施了以京津风沙源治理和退耕还林为重点的林业工程，全县林业建设彰显生态，经济和社会三大效益。     

林业生态工程对铁山库区环境影响的调查

铁山库区环境治理影响深远。在对林业生态工程和退耕还林工程实施情况的认真调查基础上进行效益分析,提出了进一步加强工程实施效果的建议。     

我省举办第一期退耕还林工程效益监测培训班

为了认真总结2004年全省退耕还林工程效益监测工作，切实搞好今后的监测工作，明确监测任务，提高技术水平，熟练掌握监测技术和方法，由甘肃省林业科学研究院、甘肃竹林业生态效益监测评估中心于2605年3月24～26日在兰州举办了第一期甘肃省退耕还林工程效益监测培训班。     

黑龙江省新一轮退耕还林工程总体规划布局及技术方法初探

黑龙江省新一轮退耕还林工程对于推动生态林业、民生林业发展、增加我国森林资源、应对全球气候变化具有重大意义。文章根据工程区内地域特征等条件,将工程区分为4个区域,并对林种、树种的选择,造林模式,造林密度等技术方法进行了初步探讨,为新一轮退耕还林工程的实施提供参考。     

数字林业技术在退耕还林工程中的应用分析

随着人们环境保护意识的提高,我国林业可持续发展的步伐正在加快,林业经营手段在不断更新和进步.自1999年以来,国家提出的退耕还林工程已在全国各地陆续展开,并且已经取得了良好的经济效益、社会效益和生态效益.随着信息技术的快速发展,数字林业技术随之产生.数字林业技术作为林业资源管理的信息化技术,在退耕还林工程中发挥了重要的...     

四川洪雅县3种植被模式的土壤入渗性能

退耕还林还草工程是我国新世纪实施的六大林业生态建设工程的重要组成部分。四川省地处长江上游，于1999年率先在全国启动退耕还林（草）试点工程，旨在防治水土流失、改善长江上游生态环境。目前关于退耕还林的报道很多，主要涉及退耕区造林模式、退耕还林工程存在问题、建议以及三大效益如何统一等方面（徐振华等，2003；傅新红等，2003；杨时文，2002）。但是，退耕还林区不同植被模式对土壤入渗率影响的系统研究相对较少（袁建平等，2001）。     

秦州区退耕还林工程20周年效益综合评价

退耕还林工程是在1998年洪涝灾害发生、沙尘暴频度和强度逐年加强、水土流失和土壤沙化日趋严重的情况下,党中央、国务院从国家生态安全角度出发,高瞻远瞩、总揽全局而启动的一项林业生态工程项目.经过20年的建设,退耕还林工程已经取得了巨大的生态、经济和社会效益.本文立足对退耕还林效益监测项目的科学研究,通过数据和客观评价,反...     

促进三大效益协调发展

略阳县近年来坚持要“被子”又要“票子”的原则,认真落实国家退耕还林政策,切实加强工程管理,提高工程质量,确保了林业生志、经济、社会三大效益的协调发展。 实施退耕还林工程以来,略阳县认真落实管护责     

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。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

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.