Regional Comparative Advantage,Location of Agriculture,and Deforestation in Brazil

ABSTRACT

This article highlights how deforestation is not only linked to economic processes within the Amazon, but also to economic forces in the rest of Brazil. In light of recent trends in Brazil's agricultural production inside and outside the Amazon, this article maintains that the growing importance of beef production in the Amazon relative to the rest of Brazil is likely to lead to further increases in deforestation. From 1991 to 2001 the Amazon's share of the Brazilian bovine herd increased from 15% to 25%—an average change of 1% per year. With the Brazilian herd size in 2003 estimated at 196 million head of cattle, the current rate of increase implies an increase of 1.96 million cattle per year in the Amazon. At Brazil's average stocking rate of 1.1 head of cattle per hectare, it means that an additional 18,000 km² of land are needed each year in the Amazon to account for this expansion. However, Brazil has abundant agricultural land outside the Amazon to meet increases in demand for beef. The difficulty lies in the comparative advantage of these other areas in producing soy and grains as opposed to livestock. I conclude that targeting resources toward specific agricultural development opportunities outside the Amazon—especially grain-fed beef— would be an effective way to reduce incentives to clear land in the Amazon.     

热带森林资源及其生态环境保护功能

综述了目前热带森林资源的现状和变化，分析了热带毁林的成因，并根据国家重点野外科学观测试验——海南尖峰岭热带林生态系统定位研究站及其他热带地区的研究成果，从热带毁林的角度探讨了热带森林生态系统的生态环境保护功能。热带毁林不仅导致林地蓄水、调洪补枯、保护森林生态系统的营养循环、调节气候等生态功能失效，而且对生物多样性保护、大气温室气体含量增加等全球性的生态环境问题产生巨大的影响，说明了保护热带森林的重要性。     

Deforestation and degradation of natural resources in Ethiopia: Forest management implications from a case study in the Belete-Gera Forest

The major causes of deforestation and degradation of natural resources in the Belete-Gera Forest of Ethiopia are coffee production activities and encroachment into forestland to expand farmland and pasture. Population growth, and the government’s land-reform and re-settlement programs have caused local residents to lose harmony with the land. Forest management in this area hasn’t yet been fully developed. The objectives of this study are to identify the extent of deforestation and natural resource degradation, in preparation for a sound management plan. Encroachment of farmland and pasture into natural forest during the past four years has been identified through interviews and aerial photo interpretation. The encroachment rate is 1.45% per year. Encroachment occurred mostly on areas with gentle slopes adjacent to populated villages and along roads and footpaths. The extent and impact of coffee production activities were examined through agency documents, forest survey data and vegetation survey. It is estimated that up to 49% of the accessible natural forest is under the influence of coffee production activities, among which collecting of naturally grown coffee beans has the least and the coffee plantations has the most impact on the natural forest. Coffee plantations in natural forest have reduced the forest density and species diversity. Age structure of the trees is limited to mature and old classes only, which eventually endangers their function as shade for coffee plantations. This project was funded by the Japan International Cooperation Agency.     

减少毁林和森林退化引起的排放:一个综述视角的分析

减少因毁林和森林退化引起的温室气体排放(REDD)对控制和减缓全球气候变暖具有重要作用。UNFCCC第11次缔约国会议将REDD议题列入气候谈判议程, 希望REDD成为2012年后承诺期减缓气候变化的重要措施之一。文中在对国际社会关于REDD的谈判进展和指导原则等进行概述的基础上, 探讨了当前国际社会关注的REDD的焦点问题, 分析了这些焦点问题的现状及其可能的发展趋势, 并据此提出讨论和建议。     

中国热带次生林区森林资源及社会经济状况——广东古兜山林区调查报告

为更好地开展热带次生林经营,在国际热带木材组织“旨在提高经济和生态效益的热带地区次生林经营研究与示范”项目（ITTO PD294／04）的资助下,对较为典型的中国热带次生林——广东古兜山林区开展了森林资源与社会经济状况的相关调查,其结果认为：中国热带林区的热带森林除自然保护区外,几乎都以低产低质的次生林状况存在,这类林分质量普遍较差,很少开展经营活动,因此缺乏经济和生态效益。林区居民主要依靠政府的生态公益林补偿、砍伐林木、出租林地供商品林经营以及农耕等获得收入,生活仍然处于比较贫困的状态,人均年收入仅3780元（约合556美元）。林农普遍的愿望是将次生林地改种以桉树为代表的速生丰产商品林经营,以获得较高的经营效益,次生林的保护仍然面临巨大的压力：     

海南岛热带森林生物多样性研究进展

生物多样性是生态学研究中一个重要的领域,海南岛热带林有很高的生物多样性。阐述海南岛热带林生物多样性的意义和研究进展,介绍海南岛热带林物种多样性、遗传多样性、生态系统多样性和景观多样性特点,结合生物多样性锐减的现状提出了相应的保护建议。     

林木施肥与桉树短轮伐期用材林施肥研究进展

林木施肥,是人们有意识地根据林木对营养元素的需求以及土壤的供给能力,将某种有机或无机的营养物质施入土壤或者喷洒在植物体上,对其进行营养补充,以满足林木健康生长的需求,维持土壤养分平衡,达到优质、高产、低成本的营林目的。介绍林木施肥、桉树专用肥、桉树平衡施肥的概况及施肥研究趋势。     

Logging Impacts in Tropical Lowland Humid Forest on Tree Species Diversity and Environmental Conservation

This study assessed the effects of exploitations in natural forest ecosystems on tree species diversity and environmental conservation. This was achieved by comparing tree species diversity and yield in an unlogged forest (Strict Nature Reserve) and a forest reserve where active logging is in progress in Ondo State, Nigeria. Eight plots (20 m × 20 m) were assessed in each site using systematic sampling techniques. All living trees with dbh >10 cm were identified, categorized into families with their diameter at breast height (dbh) measured in each plot. Shannon-Weiner and species evenness indices were used to assess and compare tree species diversity and abundance. The results show that the tropical humid forest is very rich in tree species, as a total of 54 different tropical hardwood species from 23 families were encountered in both forest types. There were 46 species distributed among 21 families in the unlogged forest and 24 species in 14 families in the logged forest. Shannon-Weiner diversity index of 3.16 and 3.03 and evenness index of .83 and .81 were also obtained for the unlogged and logged forest, respectively. Every variable computed had a higher value in the unlogged forest relative to the logged forest. In the unlogged forest, the species with the highest number of occurrence was Mansonia altissima A. Chev. (80 stems/ha). Caesalpinoidae and Sterculiaceae families had the highest number of species (6). In the logged forest, Triplochiton scleroxylon K. Schum. (18 stems/ha) had the highest frequency and Caesalpinoidae family has the highest number of species (4). The study concludes that exploitation has affected species diversity in the ecosystem and subsequently, the roles of trees in environmental conservation are affected.     

ITTO热带用材林的生物多样性保护与可持续利用

为把生物多样性保护纳入森林可持续经营, 发挥热带用材林在生物多样性保护中的特殊作用, 国际热带木材组织先后于1993年和2009年出版了关于生物多样性保护与利用的两个指南。文中以热带森林的主要利益相关者为线索, 通过比较两个指南的差别, 探讨了热带用材林生物多样性保护与可持续利用的研究进展。     

浅谈云南潞江坝经济作物的更新开发与研究

简述了云南怒江干热河谷区潞江坝热带亚热带经济作物更新开发的现状,和开发中存在种植结构不合理、灌溉条件差、生态破坏、农业科技落后等严重制约热带亚热带经济作物发展的问题;提出其更新开发见议。     

海南岛热带天然林生态环境服务功能价值核算及生态公益林补偿探讨

概述了森林生态环境服务功能的价值核算基础和现状,并以海南岛尖峰岭热带林生态系统定位研究站过去几十年的研究结论和参数,对海南岛热带天然林的生态环境服务功能价值进行了核算,总价值达43.9×108元人民币·a-1,其中森林固定CO2的价值占20.53%,O2释放价值占22.82%,森林凋落物制肥效益占6.44%,固土价值占0.81%,保肥价值占4 .19%,蓄水价值占13.49%,调洪补枯价值占24.70%,改善环境价值占7.02%。按单位面积计算,热带原始林的价值接近7000元·hm-2·a-1,天然更新林超过6500元·hm-2·a-1。最后对海南岛以热带天然林为主的生态公益林补偿提出了建议。     

热带雨林林冠层和林下层生物捕食水平的调查

指出了热带雨林作为地球上生物多样性最为丰富的生态系统,有着复杂的物理结构和生物交互。林冠层和林下层由于接受光照等条件不同,造成了不同的微环境。在不同的微环境里,蚂蚁和鸟类等捕食者对植食性昆虫的捕食水平可能有所差异。利用绿色橡皮泥制作模拟自然状态下的毛毛虫,探究了其在热带雨林林冠和林下层的被捕食的水平的差异。结果显示:林下层的捕食水平显著高于林冠层,并且蚂蚁有着显著高于鸟类的捕食水平。这说明热带雨林的林冠层资源丰富、结构复杂,在为植食性昆虫提供大量食物资源的同时也能为其提供庇护从而躲避天敌,尤其是鸟类的捕食。     

海南岛热带天然山地雨林立地质量评价研究

以森林群系（以下简称群系）为海南岛热带天然山地雨林立地质量评价基本单元（对象,）以群系优势树种组平均优势高为因变量,平均优势木胸径为自变量,用定量方法求出基准胸径为４０ｃｍ。以鸡毛松、海南油杉、岭南稠林、陆均松、线枝蒲桃、黄枝木林、白椎,鹅掌柴,黄酮林３个群系为例,建立了立地指数导向曲线模型,经模型适合性检验,理论值与实测值之间差异不显著,编制了立地指数表。     

元江6种热区森林蔬菜的驯种培育及示范种植成效

在对元江热区人工筛选出的臭菜、刺五加、南山藤、越南甜菜、长蕊甜菜、树头菜6种热区森林蔬菜植物作驯种简述后,继而介绍了此6种植物的苗木培育技术,示范种植效果以及在元江施行热区森林蔬菜种植项目所获取的经济效应。以此储备了6种热区森林蔬菜成熟的种植技术,为其大面积的推广奠定了基础。     

海南岛热带森林的变迁及生物多样性的保护对策*

海南岛是我国森林生物多样性最高的地区之一，全岛的野生植物种类约占全国的１１．６％。而由于人口的增长，工农业生产和经济建设的飞速发展，热带森林遭到了很大程度的破坏，森林覆盖率已由１９５０年的３５．４％下降到１９９０年的７．９％，全岛受国家和地方重点保护的珍稀濒危动动有１０２种，植物９３种，已灭绝的植物１种，许多物种的生存目前受到了严重的威胁。文中分析了海南岛热带森林的变迁情况、毁林原因和生物多样性锐减的现状，并提出了保护海南岛热带森林及其生物多样性的措施和建议。     

热带山地次生雨林生态系统的水文学过程及养分动态*

在小集区技术和定位观测综合实验测定的基础上，研究分析了尖峰岭热带山地雨林更新林生态系统３年间的水文学过程、水质的动态变化、营养元素积累。结果表明：水量及营养元素的输入、再分配和输出量主要集中在雨季在５～１０月份，两者月动态变化特征密切相关，年降水输入营养元素的７８％被森林生态系统积累。     

A New Function for Modelling Diameter Frequency Distribution in the Tropical Rain Forest of Xishuangbanna, Southwest of China

Permanent plots in the montane tropical rain forests in Xishuangbanna, southwest China, were established, and different empirical models, based on observation data of these plots in 1992, were built to model diameter frequency distributions.The focus of this study is on predicting accuracy of stem number in the larger diameter classes, which is much more important than that of the smallcr trees, from the view of forest management, and must be adequately considered in the modelling and estimate.There exist 3 traditional ways of modelling the diameter frequency distribution: the negative exponential function model, limiting line function model, and Weibull distribution model. In this study, a new model, named as the logarithmic J-shape function, together with the others, was experimented and was found as a more suitable model for modelling works in the tropical forests.     

西双版纳热带人工林群落结构及生态功能恢复的研究

对西双版纳普文的 6种热带人工林群落进行了近 10 0个典型的筑巢式配套样地调查。在了解 6种人工林林况的基础上 ,分析了其种类组成、林分结构和生态学特征 ,并与当地自然的热带山地雨林、季风常绿阔叶林及“黄余水”次生林进行了一系列的群落生态特征对比。认识到 6种人工林都具有显著的生物多样性恢复功能 ,其中以山桂花林 (ParamicheliabailloniiForest)的恢复效果最好。通过分析还看出它们的生物多样性恢复能力正在提高。     

退耕还林补偿问题研究综述

通过对国内退耕还林工程补偿问题相关文献的研究, 阐述了退耕还林工程经济补偿的研究现状, 分析了已有研究取得的成果以及存在的不足, 并展望了该研究领域未来的发展趋势。     

退耕还林经济补偿问题研讨

本文通过对退耕还林经济补偿相关文献的研究,阐述了经济补偿现状中的各种问题,通过对现存研究成果的分析提出完善补偿机制的对策。