A shifting cultivation land use system under population pressure in Zambia

The status of chitemene shifting cultivation, in northern Zambia was investigated and reviewed. This paper presents results concerning (a) changes in soil nutrients under chitemene shifting cultivation, (b) the relationship between population density and deforestation and (c) how the chitemene shifting cultivation system has survived under conditions of overpopulation relative to the critical population density.In the chitemene shifting cultivation system crops are grown in a small ash garden made by burning a pile of wood cleared from a larger area. The burning increased soil NH₃–N content by 40–50%, with a further increase of 15% after 262 mm of rainfall. In contrast, the soil in unburnt plots lost up to 30% NH₃–N. The content of other major nutrients, such as, P,K, Ca, Mg, and Na also increased in the top soil immediately after burning. The increase in soil NH₃–N after burning is attributed to the reduction in microbacterial activity. These soil nutrient changes appear essential in the production of finger millet.However, the growing rural population in the chitemene shifting cultivation region of northern Zambia has caused deforestation which has resulted in the reduction of (a) the length of the fallow period from 25 years to 12 years, (b) the per person woodland requirement of m 1.1 ha to 0.53 ha and (c) the frequency of clearing new chitemene gardens from yearly to once in two years. These responses to diminishing wood resources have artificially increased the population carrying capacity from 2.4 to 18.7 persons per km². This has enabled the survival of the chitemene shifting cultivation land use system in northern Zambia.     

Shifting cultivation on the tidal floodplains of Amazônia: impacts on soil nutrient status

Studies of the impact of traditional agroforestry practices on soil nutrient status in the Amazon Basin have largely been limited to upland sites, many of which are oligotrophic. However, rural population density in Amazonia is highest on the floodplains of the major rivers and shifting cultivation has been practiced on the floodplains for millennia. We established a slash-and-burn cultivation plot and an untreated forest plot in tidal floodplain successional forest in the Islands of Abaetetuba, Pará, Brazil, and sampled soils (0–10 cm) during four phases of the agroforest cycle (n = 9 in each plot for each sampling period): (1) prior to clearing, (2) following burning, (3) harvest one (rice at four months), and (4) harvest two (sugar cane at 15 months). During the course of this pilot experiment, background temporal variability in SOC, total N and available mineral nutrient pools (P, K, Ca, Mg) exceeded treatment effects, suggesting that soil nutrient pools in this environment are well-buffered against the effects of shifting cultivation. These results contrast markedly with those reported for Amazonian upland sites where nutrient pulses and declines associated with the agroforest cycle have been demonstrated and may restrict the potential for low-input, continuous cultivation. Physical limitations imposed by flooding and fluvial erosion, rather than nutrient constraints, restrict the potential of agricultural intensification in the tidal floodplains. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of shifting cultivation on biological and biochemical characteristics of soil microorganisms in Khagrachari hill district,Bangladesh

We collected soil samples from two representative sites at Aatmile of Khagarachari hill district in Chittagong Hill Tracts. One of the sites was under shifting cultivation and the other an adjacent 13-year old teak plantation. Both sites were in the same physiographic condition and same aspect with parable soil type, which enabled us to measure the effects of shifting cultivation on soil micro-flora. We studied soil physico-chemical properties and the biochemical and biological properties of soil microbes. Moisture and organic matter content as well as fungi and bacterial populations, both in surface and subsurface soils, were significantly(p ≤0.001) lower in shifting cultivated soils compared to soils not under shifting cultivation, i.e. the teak plantation site. The most abundant bacteria in surface(0-10 cm) and sub-surface(10-20 cm) soils under shifting cultivation were Pseudomonas diminuta and Shigella, respectively, while in corresponding soil layers of teak plantation, predominant microbes were Bacillus firmus(0-10 cm) and Xanthomonas(10-20 cm). The microbial population differences cannot be explained by soil texture differences because of the textural similarity in soils from the two sites but could be related to the significantly lower moisture and organic matter contents in soils under shifting cultivation.     

Building on traditional shifting cultivation for rotational agroforestry: Experiences from Yunnan,China

Under population pressure, the transition from the long-fallow shifting cultivation to short-fallow shifting cultivation with associated land degradation has been claimed to be unavoidable and sedentary cultivation would be advocated as the only future to replace the unsustainable short-fallow shifting cultivation in the mainstream research and development. The recent development of the shifting cultivation system in Yunnan, Southwest China demonstrates how local peoples hybridize elements of the traditional shifting cultivation and the new agriculture and forestry technologies as a new and dynamic rotational agroforestry system for economic development without losing the natural resource base. Comparing experiences in other regions and under some conditions, the rotational agroforestry system may be promoted as a viable option for development of the shifting cultivation system in the mountainous areas where the introduction of sedentary agriculture is much constrained.     

Causes and consequences of shifting cultivation and its alternative in the hill tracts of eastern Bangladesh

Shifting cultivation, which is still prevalent in the uplands of eastern Bangladesh, contributes significantly to forest loss and is the main cause of land degradation. This paper presents the causes and consequences of shifting cultivation and its potential land use alternatives. The analysis presented is primarily qualitative with a supplementary quantitative analysis of the causes of forest loss by logistic regression. The results of the study show that traditional land practices, exacerbated by poverty and associated with a lack of technical knowledge is the main cause for the continuation of unsustainable shifting cultivation. Population pressure, inadequate land for cultivation, low education levels, policy planning and implementation without local participation are all factors that influence farmers’ decision to continue shifting cultivation. Intensive land management through agroforestry is a promising alternative that can sustainably manage the remaining forest resources. If adopted, such systems potentially provide good economic returns, and may significantly reduce rural poverty.     

Arbuscular mycorrhizal fungi in the rhizosphere of Macaranga denticulata Muell. Arg., and their effect on the host plant

A fallow enriching tree, Macaranga denticulata Muell. Arg., has been shown to increase rice yield in a rotational shifting cultivation system in northern Thailand through increased accumulation of mineral nutrients. As arbuscular mycorrhizal (AM) fungi may play an important role in nutrient accumulation, AM fungi in the rhizosphere of M. denticulata and the effects of the indigenous soil inoculum on the host plant were investigated. The diversity and abundance of AM fungi were documented for the rhizosphere of M. denticulata in the field for two years. Based on morphology, 29 species of AM fungi were found in the rhizosphere of M. denticulata growing in farmers’ fields. Root colonization ranged from 63.5 to 81.5% in the first year and 68.7 to 79.9% in the second year of study. The highest spore density was observed at the end of the wet season. The effects of indigenous soil inoculum, and N and P fertilizers on the host plant were investigated in pots for four months. Inoculation with soil-containing AM fungi strongly increased plant growth and nutrient contents when P was limiting but N was applied. Application of N and P together strongly depressed root colonization and spore density of AM fungi, whereas applying them separately had much less effect. AM fungi may play an important role in nutrient accumulation in M. denticulata-rich fallow and thus in nutrient cycling that is beneficial to the maintenance of upland rice yield and sustainability of the rotational shifting cultivation system. This revised version was published online in June 2006 with corrections to the Cover Date.     

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 ...     

Study on soils under shifting cultivation and other land use categories in Chittagong Hill Tracts, Bangladesh

Soil samples were collected and analyzed from 25 sites of three hilly regions (Rangamati, Banderban and Khagrachari) for an understanding of the impact of denudation and land use on soils in Chittagong Hill Tracts, Bangladesh. There were natural forests, bushy land, slashed sites, slashed and burnt sites, and the sites prepared for shifting cultivation, one year after shifting cultivation and two years after shifting cultivation. The soils were generally yellowish brown to reddish brown, sandy to sandy clay loam, strongly acid, and well to excessively drained on steep slopes with considerable variation among the sites and land use categories. Bulk density was the highest in sites of one year after shifting cultivation (1.52 g·cm-3) and the lowest in forested sites (1.38 g·cm-3). Water holding capacities were, however, statistically similar in all sites. Organic carbon varied from 0.54% (slashed and burnt sites) to 1.55% (forested sites) and total N ranged from 0.05% (shifting cultivation for one year) to 0.13% (forested sites). Available phosphorus (Bray & Kurtz-2 P) was the maximum in forested sites (12.32 mg·kg-1), and it did not differ significantly in other sites. Contents of available Ca, Mg and K were also higher in the bushy lands and forested sites than cleared and shifting cultivated sites.     

Improving shifting cultivation in Southeast Asia by building on indigenous fallow management strategies

Shifting cultivation continues as the economic mainstay of upland communities in many countries in Southeast Asia. However, the conditions that historically underpinned the sustainability of rotations with long fallows have largely vanished. The imperative to evolve more permanent forms of land use has been exacerbated by rapid population growth, gazettement of remnant wildlands into protected areas, and state policies to sedentarize agriculture and discourage the use of fallows and fire. There are many compelling examples where shifting cultivators have successfully managed local resources to solve local problems. Technical approaches to stabilizing and improving productivity of shifting cultivation systems have not been notably successful. Farmer rejection of researcher-driven solutions has led to greater recognition of farmer constraints. This experience underlined the need for participatory, on-farm research approaches to identify solutions. The challenge is to document and evaluate indigenous strategies for intensification of shifting cultivation through a process of research and development. This process involves identification of promising indigenous practices, characterization of the practices, validation of the utility of the practice for other communities, extrapolation to other locations, verification with key farmers, and wide-scale extension.This revised version was published online in November 2005 with corrections to the Cover Date.     

雷竹覆盖砻糠吸放机应用初报

在雷竹笋覆盖栽培过程中,覆盖与收集砻糠是非常关键的作业环节,其人工费用占整个生产过程人工费的41.3%。砻糠吸放机的试制成功,为雷竹林覆盖栽培机械化迈出了重要的一步。设备初步应用结果显示:一台机器2人操作,667m²竹林覆盖与收集砻糠2项作业可节省9个人工,且只要3h就完成砻糠覆盖,5h完成收集和堆放作业,大大缩短了作业时间,提高了作业效率。但设备的完善和推广应用也面临着一些问题,为此文章提出了切实可行的建议。     

Brazil nut conservation through shifting cultivation

The regeneration of Brazil nut trees depends on tree-fall gaps in the forest. However, shifting cultivation fallows also create comparable biotic and abiotic opportunities for the dispersion and establishment of this gap-loving species. At the same time, the ability of Brazil nut trees to resprout enables fallow individuals to survive successive slash-and-burn cycles. Recognizing the importance of shifting cultivation for the food security of forest dwellers, we investigated whether the high level of Brazil nut regeneration found in cultivation fallows could be explained by the resprouting capability of Brazil nut trees, the number of cultivation cycles, past agricultural use and distance to the nearest conspecific productive adults. We found that the Brazil nut tree population density increased from 8.86 trees ha⁻¹ to 13.69 trees ha⁻¹ and 27.09 trees ha⁻¹ at sites after one, two and three or more shifting cultivation cycles, respectively. As a consequence of resprouting, after a certain number of shifting cultivation cycles, the fallows become dominated by Brazil nut trees, and the landholders may decide to preserve them and to exclude enriched sites from future agricultural use. Protected for their extractive value, the secondary forests spontaneously enriched with Brazil nut trees are allowed to develop into nut-producing forests that have reduced chances of conversion into crops or pastures, thus reversing the classical process of Amazon forest degradation.     

Forest villages: an agroforestry approach to rehabilitating forest land degraded by shifting cultivation in Thailand

The Forest village scheme was introduced by the Forest Industries Organisation (FIO) of Thailand in 1967 as an attempt to stop further spread of the fast increasing shifting cultivation and deforestation in the country. The underlying princple of the scheme is to relate reforestation with social welfare of the people involved. It is essentially a modification of the traditional taungya method of plantation establishment.The salient aspect of the scheme is to induce the shifting cultivators to settle down in villages where each family is given tenure over a plot of land to construct a house and develop a homegarden around it. The farmers are required to help establish and maintain forest plantations, in which they are permitted to raise agricultural crops during the first three years of its establishment. The farmers are also given free medical and educational facilities, and technical advice on crop and livestock husbandry. They can also earn cash rewards for successful plantation establishment.Although the scheme has not achieved its full target in terms of area covered and number of families settled, it is proving to be a successful method of luring people away from destructive shifting cultivation. The approach is applicable to other countries and regions with similar land-use problems and socio-cultural background.The paper also examines the constraints to the effective working of the scheme, provides some simple suggestions for improving its functioning and identies some of the issues that can easily be tackled by research.     

Agroforestry practices in Nigeria

The problems of too much pressure on land for the production of food and wood for the increasing population have made it mandatory to look into the various ways of maximising the uses of agricultural land in different parts of the world. Under this high demand for land, the system of shifting cultivation which has been practised from time immemorial can no longer support the needs of farmers in Nigeria. As a result of this, the different agroforestry practices have received increased attention. The experiences obtained with shifting cultivation, homestead gardens, taungya, alley-farming and scattered farm tree methods including shelterbelt planting in the country are reviewed in this paper and some research findings on these practices are highlighted.     

Land-use options to encourage forest conservation on a tribal reservation in the Philippines

The Negrito (Ati) tribe of Nagpana, Iloilo, Philippines has traditionally been dependent on shifting cultivation and on hunting and gathering of non-timber forest products for its livelihood. In recent decades the Ati have derived increasing income from wage labor for adjacent landowners and from permanent rice cultivation. The consequent clearing of residual forests has resulted in extensive soil degradation, reduced crop yields, and loss of both commercial and subsistence non-timber forest products.Various agroforestry systems which incorporate permanent tree crops into traditional systems have great potential to reverse these losses. This study analyzes the economic sustainability of four different land-use options for the Ati. The net present value (NPV) of a system which incorporates both sustainable use of the existing forest and plantations of fast-growing tree species on agricultural lands is superior to all other alternatives. Social and environmental benefits from this system further justify implementation. Any recommendations to develop such an option must take into account the constraining factors typical of such upland communities.     

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.     

The relationship between length of fallow and crop yields in shifting cultivation: a rethinking

Rethinking the relationship between length of fallow and crop yields inshifting cultivation?The theory that a correlation between shortened fallow periods and yielddecline in shifting cultivation exists is questioned in this paper. Thisrelationship has been taken for granted, and because it shows that shiftingcultivation will break down under pressure, it has partly been responsible fornegative government views on shifting cultivation. Yield levels in shiftingcultivation are influenced by a wide range of biophysical, socioeconomic, andcultural factors and it is difficult to isolate fallow length as a singledetermining factor. A total of 330 studies were reviewed and fifteen withempirical data were chosen for in-depth analysis. Although most of the empiricalstudies support the theory, the data sets are often ambiguous and importantparameters are insufficiently taken into account. Several studies found norelationship between fallow length and yield, but these also lack information toverify the validity of the data. It is concluded that empirical studiesfocussing on this problem are needed to fully understand this relationship anddevelop feasible scenarios for the numerous attempts at modelling shiftingcultivation development. Moreover, the use of gloomy `breakdown' scenarios asjustification for improving shifting cultivation should be avoided.     

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.     

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。     

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.     

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.