Effect of shifting cultivation on soil physical and chemical properties in Bandarban hill district, Bangladesh

This study reports the effects of shifting cultivation at slashing stage on soil physicochemical properties at Bandarban Sadar Upazila in Chittagong Hill Tracts of Bangladesh. At this initial stage of ...     

轮换种植对孟加拉国吉大港山区土壤中真菌和细菌群落的影响

在孟加拉国吉大港山区选择两块研究地,研究轮换种植对土壤中真菌和细菌群落的影响。两块研究地均包含轮换种植和本地社区管理的乡村森林,第一块研究地点选择在兰加马蒂地区,第二块研究地点选择在吉大港的班多尔班地区。在两个地点和不同用途的地块中,其表面土（0-10cm）和地表下土（10-20cm）的土壤质地不同,分别为砂壤和粘土。轮作地的土壤pH和含水量比乡村森林的低。研究结果表明：在兰加马蒂和班多尔班地区,大多数情况下,轮作地的表面土和地表下土壤中的真菌和细菌群落数量比乡村森林的低。在兰加马蒂和班多尔班地区的轮作地中,炭疽菌属（CoHetrotrichum）和镰孢菌属（Fusarium）真菌稀少,而两个地方的不同用途地块中均有细菌球菌属（Coccus）,芽孢杆菌属（Bacillus）和链球菌属（Streptococcus）。在两个地方的不同用途地块中常见的真菌有曲霉属（Aspergillus）、根霉属（Rhizopus）、木霉属（Trichoderma）和青霉菌属（Penicillium）。在其它的土壤区系中,由于轮换种植导致土壤环境退化的程度还需要进一步的研究。     

海南岛尖峰岭热带林生态系统研究(续)——Ⅴ.游耕农业的生态后果Ⅵ.更新与演替Ⅶ.简要结论

热带林地经游垦后气温和土温增高,相对湿度降低,水土流失加剧,地表迳流加大,土壤入渗量减少,贮水能力减弱,肥力下降。反复烧垦后形成茅草坡,难以恢复。热带林的更新和演替方向视采伐方式及人为活动干扰程度而异,采取保持郁闭度0.4以上的择伐,对森林恢复比较有利,尖峰岭林区今后经营方向应以保护为主。     

黄河三角洲盐碱地林木衰退原因及对策

林木衰退是黄河三角洲盐碱地防护林生态功能退化甚至逐步丧失的主要原因.文中在调研黄河三角洲土壤盐分时空变异特征的基础上,分析该区域土壤盐分反复表聚、树种选择适应性不强、栽培技术针对性不够、抚育管理缺位及干旱和病虫害等因素对林木生长的影响,明确了引起黄河三角洲盐碱地林木衰退的原因,并提出解决林木衰退问题的对策:1)因地制宜...     

基于GIS的老挝-中国边境土地适用性评估

对老挝-中国边境林地使用变更进行了评估,并提出了茶叶的土地适用性。建立一个综合的基于GIS的分析系统（IGAS）,该系统支持老挝-中国边境的林地使用和土地适用性的评估研究。采用多标准分析和系统动态技术评估林地使用和土地适用性,同时预测了潜在的茶叶用地。收集到的土地数据和数据分析表明,整体研究区域为10325.07 km2,当前的森林覆被由1992年的6337.33 km2（占61.38%）减少到2002年的5106.28 km2（占49.46%）。当前的森林主要被转为潜在林地和专门的永久农业用地,甚至国家生物多样性保护区域被转为橡胶种植区。林地使用转变的主要原因是贫穷。为了解决这个问题,根据多标准方法,我们对研究区域中适用茶叶种植土地提出了2种分类方案。     

Rural land-use and wildland fires in the tropics

Tropical forest land is increasingly influenced by man-caused wildfires. The vast majority of the forested area burnt and cleared annually is in the tropics. The use of fire in rural land-use systems is the major cause of the wildfires. Five broad causative agencies of wildfires are presented, shifting cultivation, grazing, non-wood forest products, migration programs and the wildland/residential interface. Integrated concepts of prescribed burning and prescribed grazing may offer solutions to the tropical wildland fire problems.     

内蒙古黄河流域及京津周围地区生态环境存在问题及建设的必要性

文章分析了内蒙古自治区黄河流域及京津周围地区生态环境现状 ,认为水土流失、土地荒漠化、草原退化是这一区域生态环境恶化的主要原因。有林地面积少 ,森林覆盖率低 ,自然灾害严重 ,生态建设投入严重不足是这一区域生态环境存在的主要问题。从抓住西部大开发机遇 ,加快我区经济发展 ,使农牧民脱贫致富等几个关键问题上论述了这一区域林业生态环境建设的必要性。     

Rural land-use and wildland fires in the tropics

Tropical forest land is increasingly influenced by man-caused wildfires. The vast majority of the forested area burnt and cleared annually is in the tropics. The use of fire in rural land-use systems is the major cause of the wildfires. Five broad causative agencies of wildfires are presented, shifting cultivation, grazing, non-wood forest products, migration programs and the wildland/residential interface. Integrated concepts of prescribed burning and prescribed grazing may offer solutions to the tropical wildland fire problems.     

Shifting cultivation in steeply sloped regions: a review of management options and research priorities for Mizoram state,Northeast India

Shifting cultivation is a common agricultural practice that is the basis of subsistence for many rural populations throughout the Tropics. The recent strong trend towards shorter fallow periods has led to widespread concern about declines in soil fertility, crop yields, and food security. Unlike most research on this problem, we focus here on steeply sloped regions such as Mizoram state in northeast India where most land is at an incline of >33°, and the potential for relatively large soil erosional losses may necessitate distinctive solutions. Our goal is to review the relevant literature so as to optimize the direction and quality of future science research on shifting cultivation in Mizoram. Our analysis suggests that the most promising options for improving shifting cultivation are nutrient and water supplementation, optimising crop choice, extending the site use period, enhancing the fallow recovery rate, and controlling the burns and their environmental impacts. Promising alternatives for replacing shifting cultivation include inter-row cropping between contour hedgerows of nitrogen-fixing shrubs, slope terracing, agroforestry with anti-erosional plants, and bamboo forest harvesting. In addition, we identify the principal research questions that should be addressed before each of these options can be evaluated and recommended as part of land use planning initiatives. Overall, we conclude that intelligent and careful use of commercial fertilizer in combination with organic matter additions is likely to be an important feature of many of the solutions to the problem of shortening fallow periods in shifting cultivation on steep slopes.     

望天树林次生演替趋势初探

针对云南省原始望天树林遭受不同程度毁坏的状况，以轮耕撂荒后，人为影响少，自然恢复起来的望天树次生林作为研究对象，从不同坡向（阳、阴坡）及时间系列的角度分析了望天树次生林树种种类的更替以及层次结构的变化趋势，以此研究望天树林的演替过程，为保护和恢复望天树林提供依据。     

Community Dependency on Forest Resources in West Java,Indonesia

Abstract

Policies aimed at the exclusion of local communities from forest management are inappropriate, especially in a densely populated area with a low level of land ownership. Here we demonstrate that termination of the Tumpang Sari program, which allowed local communities access to areas for controlled cultivation in several parts of the state forest area in West Java, Indonesia, did not cease illegal cultivation of the forestland. Moreover, illegal cultivation continues to be conducted by many people. This has created not only a land degradation problem but also has affected other forest resource users, the fuelwood collectors and the dairy cattle farmers. Therefore, the re-involvement of local communities in better forest management is required to avoid further environmental degradation as well as enhance poverty alleviation programs.     

Introducing Cash Crops in Shifting Cultivation Regions – The Experience with Cardamom in Laos

Farmers are often blamed for destroying the tropical forest, especially in Laos. Converting shifting cultivation into cash crop based agriculture is frequently presented as the solution for merging forest protection and poverty alleviation, but many attempts have ended in failure. A rural development project has attempted to introduce medicinal cardamom (Amomum villosum) cultivation in the notably remote region of Phongsaly (northern Laos), for export to China. With nearly 300 ha planted, the crop now involves about 75% of the farmers in the region. Farmers fitted cardamom into their farming system, to suit their needs for sustainability with a crop compatible with existing practices. Results indicate that introducing a cash crop into a shifting cultivation region is possible if a greater attention is paid to: (i) appraise how the new crop fits into the farming systems; (ii) prioritise economic issues over agronomic matters, in particular identify markets, traders or commercial risks.     

Changes of land tenure and the introduction of tree cash crops by shifting cultivators: The case of the Paluan Muruts in Sabah, Malaysia

Shifting cultivation is one of the main factors that has caused forest degradation in many tropical countries. In Sabah, Malaysia, the government has granted land titles to local farmers outside the Forest reserve, and introduced tree cash crops to reduce farmers’ dependence on shifting cultivation. Granting land titles, however, was not always an incentive for farmers to plant tree cash crops. Farmers often planted tree cash crops on land without secure legal rights. The Land Ordinance and illegal logging had introduced exclusive and (semi-)permanent rights to land into this region, and the Forest reserve also was divided among villagers. The Land Ordinance stipulates that planting trees confers permanent heritable and transferable rights of use and occupancy but not within Forest reserves. Local farmers who were anxious about their land rights believed that they could obtain those rights even within the Forest reserve, and applied for land titles. Farmers planted tree cash crops not only for future income but also to secure their land rights. At present, the policy of Forest reserve has nearly collapsed in this region and it is impossible to neglect or remove local farmers if the government utilizes Forest reserves for any purpose. Lands in the interior regions will be reclassified in the near future out of necessity.     

Loss of carbon sequestration potential after several decades of shifting cultivation in the Southern Yucatán

Cumulative losses from shifting cultivation in the tropics can affect the local to regional to global balance of carbon and nutrient cycles. We determined whether shifting cultivation in the Southern Yucatán causes feedbacks that limit future forest productivity and carbon sequestration potential. Specifically, we tested how the recovery of carbon stocks changes with each additional cultivation-fallow cycle. Live aboveground biomass, coarse woody debris, fine woody debris, forest floor litter and soil were sampled in 53 sites (39 secondary forests 2–25 years old, with one to four cultivation-fallow cycles, and 14 mature forests) along a precipitation gradient in Campeche and Quintana Roo, Mexico. From the first to the third or fourth cultivation-fallow cycle, mean carbon stocks in live aboveground biomass debris declined 64%. From the first to the third cycle, coarse woody debris declined by 85%. Despite declining inputs to soil with each cultivation-fallow cycle, soil carbon stocks did not further decline after the initial conversion from mature to secondary forest. The combined aboveground and soil carbon stock declined almost 36% after conversion from mature forest, however two additional cultivation cycles did not promote further significant decline, largely because of the stability of the soil carbon pool. Although age was the dominant factor in predicting total carbon stocks of secondary forests under shifting cultivation, the number of cultivation-fallow cycles should not be neglected. Understanding change beyond the first cycle of deforestation will enhance forest management at a local scale by improving predictions of secondary forest productivity and related agricultural productivity. A multi-cycle approach to deforestation is critical for regional and national evaluation of forest-based carbon sequestration. Finally, models of the global carbon cycle can be better constrained with more accurate quantification of carbon fluxes from land-use change.     

The farming system and traditional agroforestry systems in the Maya community of San Jose, Belize

Shifting slash-and-burn agriculture is likely one of the main causes of forest degradation in southern Belize. Although many development projects have attempted to reduce the impacts of agriculture on the tropical rainforest, the situation is still a cause for concern. A study of the farming system of the San Jose Maya community was therefore carried out to examine agricultural production in its social, cultural, economic, and political context. Results demonstrate that agricultural production contributes to forest degradation because of the limited availability of agricultural land, the low level of investment in agricultural production, the land tenure system, limited marketing opportunities, and the exclusion of Mayas from the country's political and economic domains. Agroforestry could, however, offer a partial solution to the problem of forest degradation. Three types of traditional agroforestry systems are practised in San Jose: the milpa (a slash-and-burn agriculture system), cacao (Theobroma cacao) cultivation under shade trees, and the homegarden. These traditional agroforestry systems almost entirely meet a family's needs for food and wood, and generate at least 62% of family income. Improving the productivity of these systems could help to reduce pressure on the forest in southern Belize.This revised version was published online in November 2005 with corrections to the Cover Date.     

巴林左旗林业生态系统分析与森林培育措施

巴林左旗现有的森林资源的林分质量不高,但林地生产力的潜力较大,要把提高林地生产力定为巴林左旗发展森林资源的主攻方向之一,把培育发展和保护森林资源做为林业工作的中心任务,坚持以保护森林资源为前提,以培育发展森林资源为中心,走保护与培育发展并重的道路。文章对该旗的林业生态系统进行分析,并针对该旗森林资源培育中的一些问题提出了建设规划建议。     

The Upland Settlement Project of Bangladesh as a Means of Reducing Land Degradation and Improving Rural Livelihoods

Because of illegal logging, increased population pressure and intensified shifting cultivation, forest coverage of the Chittagong Hill Tracts (CHT) has decreased drastically resulting in land degradation. Many development projects have been implemented to combat forest loss and land degradation and also to improve the livelihoods of the hill people. This paper reports an empirical study of the Upland Settlement Project (USP) of Bangladesh which was undertaken to prevent land degradation and enhance the standard of living of the people. Planters were found to have given up shifting cultivation and adopted soil conserving agroforestry practices, and forest coverage has been increased in the project village. Interacting with project staff members, government officials and NGOs assisted planters in diversifying livelihood strategies thereby reducing dependency on project resources. Rich planters, utilizing their own capacity, expanded their income sources successfully. Poor planters still remain wage labourers because they do not have sufficient finance and networks to invest in productive ventures. Planters’ participation in project activities and the information flow between them and project staff were found to be minimal. Suggestions are made for the continuity of project functions, which involve greater participation of planters in rubber management functions, improved information flow, resolution of land tenure and greater equality in distribution of rubber revenue.

Impact of oil palm plantations on the structure of the agroforestry mosaic of La Gamba, southern Costa Rica: potential implications for biodiversity

Human activities often cause changes and homogenization in landscape structure. To investigate the impact of changing cultivation systems on structural and functional aspects of a tropical agroforestry system, we developed satellite based land cover maps of the La Gamba area in southwestern Costa Rica and refined them by mapping fine-scale linear landscape elements. Performing a landscape pattern analysis, we compared eight sections of the study area by landscape metrics. Furthermore we performed a Morphological spatial pattern analysis (MSPA) for hypothetical non-forest, forest generalist and forest specialist species, and compared the current situation to a possible future scenario with double the area covered by oil palm plantations after a virtual conversion of other agricultural patches. The heterogeneous rural sections clearly differed from the homogeneous forests and especially pasture-dominated rural sections included many diverse, small and elongated patches, many linear landscape elements but few big plantations. According to the scenario with double the area covered by oil palm plantations, non-forest species lost large parts of their habitat, while forest species mainly lost corridors. The protection of natural landscape elements that support wildlife movement between forest areas is of major importance, particularly as the globally increasing cultivation of oil palm is significantly altering many tropical land mosaics, including the countryside of La Gamba. We propose the establishment of eight least cost path corridor routes in the study area to make the agricultural area pervious for wildlife.     

Intensive plantation cropping,a source of sustainable food and energy production in the tropical rain forest areas in southeast Asia

About 90% of the annual losses of tropical rain forests are caused by transformation into arable land. Most of the cropping activities on the former forest land are characterised by low input, partly shifting cultivation practices, leading to fast degradation of the lands which are finally abandoned owing to infertility. Success in protecting land from further degradation is determined by the economic viability of the respective system. Therefore, sustainability of agricultural systems depends on their economic sustainability. Intensive plantation cropping on former rain forest land appears to offer such an incentive to prevent the land from further degradation by employing the best technology available.Examples of intensive oil palm cultivation as a sustainable cropping system, in terms of economy and ecology, are given. Oil palm cultivation in a suitable environment outyields most annual crops and reveals a significant potential for efficient conversion of solar energy.With the employment of sound agronomic measures the present production potential can be fully realised and new techniques in the production of tissue cultured planting material provide further improved economic viability and environmentally sound cropping systems. Such an intensification offers excellent prospects for reducing the rate of deforestation in the humid tropics.