The effects of cultivation history on forest recovery in fallows in the Eastern Arc Mountain, Tanzania

Using fallows under shifting cultivation systems as a case study, we examined the effects of landuse history (cultivation duration and cropping strategies) on rate and extent of forest recovery. Cultivation duration and five cropping strategies were investigated post facto, indirectly, and with regards to their effect on the structure (basal area, BA and stand complexity, C_HCI) and diversity (Fisher's α) of forests in fallows. Data were generated from vegetation surveys conducted in the Nguru Mountain block of the Eastern Arc Mountains, Tanzania. The surveys were conducted in primary forests, ongoing farms, and fallows that had been out of production for 1-31 years (N = 109, plot size = 0.1 ha). Recovery patterns between lowland (300-800 m) and submontane (800-1600 m) elevations varied substantially. BA and C_HCI recovery levels were consistently higher in submontane fallows. None of the fallows had attained BA and C_HCI levels equivalent to those of primary forests; α in lowland fallows, however, was 124% of primary forest levels. Forest recovery was limited to fallows whose cultivation period was ≤16 years. Recovery was fastest and highest in fallows located within a dense primary/old growth forest matrix. The findings provide a more thorough understanding of how local farming practices affect forest recovery. Improving the recovery outcomes of fallows that are located outside the old growth forest matrix will require (a) more strategic inclusion of remnant trees, (b) drastically shorter cultivation periods, and (c) human intervention through assisted regeneration.     

Personal preferences and intensification of land use: their impact on southern Cameroonian slash-and-burn agroforestry systems

Where long forest-fallows are no longer practiced, productivity declines in the absence of input substitution, as does the ability of subsistence farmers to earn an adequate livelihood from shifting cultivation. Land availability, population density and productivity-related factors such as soil fertility and labour requirements are not the only factors that affect fallow length and land use intensification in shifting cultivation agroforestry systems. Households surveyed indicated that various other decision criteria (e.g., proximity to other fields and the protection of land use rights) are important in land use decisions. Even though one quarter of households reported insufficient land resources to maintain soil fertility, few actually indicated that their choices were constrained by land availability. In fact, many cleared much younger fallows than strictly necessary based on the age of fallows available in their land holdings – even those with fallows of sufficient age to maintain long-term productivity. This paper outlines an approach to quantify information about the household preferences that influence land use decisions, discusses the implications of these decision criteria for land use intensification and uses them to model household decision-making in a way that effectively simulates the spatial and dynamic mosaic of land use characteristic of shifting cultivation. Not only are non-productivity related decision criteria important in land use decisions in general; they also have a significant impact on land use intensification. In fact, the research described here demonstrates that both household-specific preferences and household-specific initial conditions can lead to intensification of land use apart from that arising due to increasing population density.     

Small-scale agroforestry for upland community development: a case study from Chittagong Hill Tracts, Bangladesh

The potentialities of agroforestry are generally investigated through their biophysiological phenomena, cost–benefit analysis, and possible impact upon poverty reduction. There have been inadequate studies on the actual impacts of agroforestry intervention on small landholders and of farmers' attitudes toward these agroforestry programs. Drawing upon the findings of an empirical study, this article explores the effects of small-scale agroforestry on upland community development in the Chittagong Hill Tracts, Bangladesh. More specifically, the study clarifies the merits and demerits of different agroforestry systems as perceived by farmers, their impacts on the rural economy and the environment, farmers' attitudes toward the adoption of agroforestry, and impacts of various government policies. Field data were collected by administering questions to 90 randomly selected smallholders of the Upland Settlement Project (USP), as well as from project staff. The research tools employed were semistructured interviews, group discussions, and uncontrolled observations. The results indicated that the agroforestry interventions have in fact increased farmers' income through employment and the selling of farm products, as well as by improving the ecological conditions of these areas through reduction of soil erosion, increasing tree coverage, and maintaining soil fertility. The adoption of different agroforestry systems was governed mainly by the farmers' interests in following these techniques, their ability to cultivate the land in the prescribed manner, and the market demand for their products. The major obstacles that prevented increased agroforestry improvements included lack of confidence in new land-use systems, inappropriate project design (e.g., top-down innovation approach), and policy issues regarding land tenure. Recommendations are proposed to strengthen social capital in local organizations to enhance the livelihoods of the upland communities.     

Dynamics of fallow successions and introduction of robusta coffee in shifting cultivation areas in the lowlands of Papua New Guinea

The traditional shifting cultivation system in the lowlands of Papua New Guinea consists of mixed food crop gardens in which yams (Dioscorea spp.), bananas, taro (Colocasia esculenta) and sugarcane predominate. The cropping cycle is usually for 18 months, followed by a fallow cycle of up to 30 years. During the cropping cycle, two species of fruit trees, Pometia pinnata and Artocarpus altilis are also planted, the leaves of the former also being used as a mulch and green manure in yam cultivation. Fallow succession follows rather systematic patterns about which farmers have a thorough understanding. Robusta coffee, a cash-crop component, has been added to the system in some areas since the late 1950s. It is usually grown in permanent blocks, but is interplanted with Leucaena as shade. Food crops are planted in the establishment stage, bananas and Xantohosoma being retained even in mature coffee gardens. The system seems to be a potentially promising one. But very little quantitative information is available on the production and performance of the system and practically no systematic research has been undertaken. Since the Papua New Guinea fallow gardeners are willing to accept innovations, it will be appropriate and timely to undertake serious studies so that the system can be improved. A few items that merit immediate research attention are indicated.     

降低路基高度是减少工程造价的一种有效方法

本文针对我国高等级公路建设中路基普遍较高的现象,分析了高路堤的缺陷,并提出了结合路线设计和根据工程地质条件以及采取置换法等措施,尽可能地降低路基高。度减少工程造价,提高公路整体效益。     

工程车辆挡位决策的自适应神经模糊推理系统

提出了一种自适应神经模糊推理系统，并利用在ZL50E装载机传动系统换挡实验中获得的数据进行验证性仿真。仿真结果表明，该档位决策系统可根据操作工况环境实现正确的变速箱挡位决策。它将模糊推理与神经网络有机地结合起来，克服了模糊推理不具备学习功能和神经网络不能表达模糊语言的缺点，使模糊推理与神经网络的应用范围更加广泛，是实现挡位决策的行之有效的方法。     

提高液力变矩器输出功率为目标的换挡规律

提出了一种以提高液力变矩器涡轮输出功率为目标的换挡规律,运用Matlab／Simulink建立了仿真模型．验证换挡规律的正确性。结果表明,该换挡规律可以提高涡轮的输出功率,对改善工程车辆的动力性和节能有实际意义。     

Role of earthworms in nitrogen cycling during the cropping phase of shifting agriculture (Jhum) in north-east India

We investigated the role of earthworms in the N cycle in a shifting agriculture system under a 5- and a 15-year Jhum system fallow period intervening between two croppings on the same site. Earthworms participated in the N cycle through worm cast egestion, mucus production, and dead tissue decomposition. Soil N was initially depleted by volatilization during slash and burn operations, and subsequently during cultivation processes. These losses were more pronounced under the 15-year Jhum system. We also studied the addition of N to the system in crop residues, through weed recycling, or in compost applied as organic manure under both the 5- and the 15-year Jhum systems. The total soil N made available for uptake by the plant through the activity of earthworms in this agro-ecosystem was higher than the total input of N to the soil through the addition of slashed vegetation, inorganic and organic manure, and recycled crop residue and weeds. Therefore, in highly leached soils of the humid tropics, worm activity is particularly, important because of rapid incorporation of litter into the mineral soils and because of local concentrations of nutrients in the surface soil layers.     

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.

Exploring the Socio-Economic Situation of Plantation Villagers: A Case Study in Myanmar Bago Yoma

Since the early 1980s, Myanmar Forest Department has been recruiting shifting cultivators, establishing plantation villages and applying the taungya method in establishing teak plantations. From the beginning, there has been an argument about whether the program is creating ‘forest protective groups’ or ‘forest destructive groups’. A key determinant to that question from the research viewpoint is the socio-economic situation; knowing the present situation of the plantation villagers can help to understand their forest management practices. Interview surveys were carried out in three villages in Bago Yoma, the main region of the special teak plantation program, to examine the current economic benefits to plantation villagers. Questions were designed mainly to explore the incentives for people participation and the socio-economic situations of the plantation villagers. Principal component analysis was used to group landholder types. It was found that local people are willing to participate in the initial establishment of plantations. However, all the incentives relating to plantation projects are temporary, with no long-term consideration for taungya farmers, which jeopardizes the plan to create forest protective groups. It is concluded that the time has come for the Myanmar Forest Department to change its main aim of earning foreign exchange from establishment of teak plantations through the taungya method to redressing deforestation through people participation based on rural socio-economic development.