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1.
Weed suppression is an important reason for fallowing in swidden systems. Recently, in Laos, an increase in weeds and resulting increase in labor input has become a problem; however, causal factors influencing weed growth and weeding labor other than fallow period have yet to be fully examined. Therefore, an experimental research on swidden weeds, combining a forest survey and interviews with local farmers, was conducted in a mountain village in northern Laos where swidden agriculture is practiced as a major means of livelihood. Weed amount, weed composition and time required for weeding were found to be more influenced by fallow vegetation than fallow period. Bushy vegetation in a short fallow field was shown to lead to abundance of herbaceous weeds, resulting in higher labor input. There was a possibility that increases in some bamboo species were a cause of recent weed increases. Based on the results, we suggest that maintaining a minimum fallow period of forest fallowing, with fallow management to suppress bamboo and promote tree growth may be effective in reducing labor input in swidden agriculture. 相似文献
2.
Jon D. Unruh 《Agroforestry Systems》1988,7(2):161-184
The ecological importance of fallowing to swidden (slash and burn) agriculture is well known. Cyclic agroforestry systems which emphasize utilization of the fallow cycle should, where appropriate, consider the ecologic processess of site recovery, so as not to impair the productivity of the subsequent swidden cycle. this artical discusses the ecologic ‘fit’ of a cyclic swidden-fallow management scheme into swidden cultivation and fallow succession. Such a fit suggests a reciprocally reinforcing situation between this agroforestry design and processes involved in site recovery. Observed among some indigenous and colonist inhabitants of the Peruvian Amazon, this system produces fallow crops and products, while enhancing site nutrient recovery. The economic benefits of this scheme have recently been reported (Denevan and Padoch, n.d.) while the ecologic attributes involved in promoting site recovery have not; primarily these include:
- Less destruction of the nutrient cycling root-mat in the swidden cycle, and its quicker re-formation in the fallow cycle.
- Discouraging the establishment of exotic, pantropical weeds and grasses such as imperata, while encouraging the colonization of local, early successional species.
- Encouraging the earlier establishment of woody plants in abandoned swiddens.
- A natural litterfall higher in nutrients than in unmanaged fallows.
- Additions of ‘slash’ litterfall higher in nutrient content than natural litterfall in the proximity of valuable managed plants.
- The increased capacity of the managed stand to scavenge limiting nutrients such as N and P from, and leach unneeded quantities of non-limiting nutrients such as K, Ca and Mg to, thoughfall.
- Increasing the alkalinity of throughfall, possibly resulting in less soil cation leaching in managed fallows.
- Staggering seed production, germination and maturation times of the rapid nutrient sycling softwood trees.
- Increasing the spontaneously occuring abundance of valuable fallow plants with management of successive fallow cycles, thereby possibly reducing the labor requirement, and increasing the value of this agroforestry scheme over time.
3.
在撒哈拉以南的非洲地区,黄独脚金寄生杂草（Strigahermonthica）侵扰是限制小农产自给性农业生产的主要因素之一。土壤肥力低加之总体环境退化是寄生杂草侵扰产生的重要原因。引入改良的耕作制度来解决寄生杂草侵扰和土壤肥力下降的问题势在必行。本文对肯尼亚西部双峰高原地区内,用豆科植物--印度田菁改良的休耕地对玉米产量和农田寄生杂草侵扰的作用进行了研究。实验处理分阶段进行,处理包括田菁改良6和18个月的休耕地、未经耕作自然植物再生6和18个月的休耕地、连续种植玉米未施肥的耕地和连续种植玉米同时施加氮和磷肥的耕地。结果表明,与未施肥玉米地相比,田菁改良休耕地明显（p〈0.5）增加玉米产量.除草管理降低了第一季度（428000±63000株·hm-2）、第二季度（51000±1500株·hm-2）玉米地寄生杂草植株种群。实验周期内,除草管理降低玉米地土壤中寄生杂草种子种群数。短期田菁改良休耕地对玉米产量的促进作用明显好于未施肥的玉米地,但是短期杂草休耕地对玉米产量无显著影响。种植玉米和除草控制寄生杂草效果要好于休耕。 相似文献
4.
Sovu Mulualem Tigabu Patrice Savadogo Per Christer Odén Lamphoune Xayvongsa 《Forest Ecology and Management》2009
Species composition, structure and diversity of secondary forests recovered on abandoned swidden cultivation fields in the lowland of Laos were studied in relation to distance from the natural forest, fallow age and crop-fallow rotation cycle. All woody species with stem diameter ≥1 cm were identified, counted and their diameter at breast height (1.3 m, dbh) measured on 290 plots in 162 swidden fallows. Distance from the forest edge related non-linearly and explained 46%, 54%, 63% and 52% of the variation in species richness, stem density, basal area and Simpson's index, respectively. The basal area of secondary forests increased significantly (p < 0.0001) while stem density tended to decrease (0.05 < p < 0.1) with increasing fallow age, whereas species richness and diversity measures remained insensitive. Species richness, stem density, basal area and Shannon-Wiener index were reduced by 28%, 35%, 72% and 23%, respectively while the number of bamboo clumps increased significantly by 45% as the crop-fallow rotation cycle increased from one to three. The occurrence of bamboo had a negative effect on most of the vegetation characteristics analyzed. From forest production and biodiversity conservation viewpoints, it is recommended that the natural regeneration in fallows with a history of previous severe land use intensity should be supplemented with enrichment planting irrespective of its distance from the natural forest. Although the management objectives for secondary forests on swidden fallows are not clearly set, promoting the development of bamboo forests in fallows would be one management option, given its importance in rural livelihood. 相似文献
5.
The Kenyah Dayak people began to migrate from the isolated area to the Mahakam basin in the early 1950's. As the Kenyah people migrate downstream, infiltration of monetary economy into the village increases, which leads to changes of life style, social structure such as work organization and mutual aid system in daily life, and so on. In the course of a series of such changes, sustainable swidden agriculture system is also changed to a less sustainable one. The Benuaq Dayak people, however, practice sustainable swidden (paddy) — rattan forestry system while they can earn much income. The Buginese way of land utilization, swidden (paddy) — pepper production system, is the least sustainable though the pepper production is the most profitable in the region. The land utilization by the transmigrated Javanese is not so sustainable at present, but there is a possibility of its getting more sustainable because of acquisition of the land ownership. 相似文献
6.
Striga hermonthica is a major constraint to smallholder subsistence agriculture production in the sub-Saharan African region. Low soil fertility
and overall environmental degradation has contributed to the build-up of the parasitic weed infestation. Improved cropping
systems have to be introduced to address the interrelated problems of S. hermonthica and soil fertility decline. Thus, the effects of improved fallow with leguminous shrub Sesbania sesban on maize yields and levels of S. hermonthica infestation on farm land in the bimodal highlands of western Kenya were investigated. The experimental treatments were arranged
in a phased entry, and randomized complete block scheme were six months Sesbania fallow, 18 months Sesbania fallow, six months natural fallow consisting of regrowth of natural vegetation without cultivation, 18 months natural fallow,
continuous maize cropping without fertilizer application, and continuous maize cropping with P and N fertilization. Results
show that Sesbania fallows significantly (p<0.05) increase maize yield relative to continuous unfertilized maize. S. hermonthica plant populations decrease in continuous maize between the first season (mean = 428 000 ± 63 000 ha−1) and second season (mean=51 000 ± 15 000 ha−1), presumably in response to good weed management. S. hermonthica seed populations in the soil decrease throughout the duration of the experiment in the continuous maize treatments. Short-duration
Sesbania fallows can provide modest yield improvements relative to continuous unfertilized maize, but short-duration weedy fallows
are ineffective. Continuous maize cultivation with good weed control may provide more effective S. hermonthica control than fallowing. 相似文献
7.
Prasit Wangpakapattanawong Nuttira Kavinchan Chawapich Vaidhayakarn Dietrich Schmidt-Vogt Stephen Elliott 《Forest Ecology and Management》2010
Rotational swidden cultivation systems, with fallow periods long enough for the regeneration of secondary forests are capable of maintaining forest cover and plant diversity in a dynamic balance in swidden cultivation landscapes. Regeneration of secondary forests through several successional stages and by a combination of coppicing and seedling development is still poorly understood, especially the influence of different swiddening practices and the role of animals as seed dispersers. Swidden cultivators possess a vast knowledge of plants growing in swidden fallows and of fallow dynamics as well. Forest restoration in Thailand has been carried out mainly on the basis of experimental research on the potential of indigenous tree species to promote natural forest regeneration and biodiversity recovery; the so-called framework species. Another viable source of knowledge for forest restoration can be the study of the semi-natural revegetation processes in fallows and the indigenous knowledge of swiddeners of these processes. The research presented here was carried out to attain a better understanding of forest regeneration on fallow swiddens under different swiddening regimes and how it may be applied to practical forest restoration, We investigated the vegetation characteristics of from various stages of secondary succession in fallow swiddens of the Karen and Lawa ethnic groups in the Mae Chaem watershed, Chiang Mai province, northern Thailand. Indigenous knowledge on the use of species and traditional ecological processes in swiddening was recorded by questioning key informants. The data were analyzed and discussed with respect to their application in forest restoration and participatory forest management. 相似文献
8.
9.
《Journal of Sustainable Forestry》2013,32(4):19-32
Abstract East African forests have been largely converted to agriculture. The remaining forests hold many endangered species but are threatened by the heavy local demand for fuelwood. Here we evaluate fallow land in western Uganda as an alternate fuel source to diverse forests. We quantify the regeneration process on fallows, calculate tree bio-mass increases, and measure grass and woody herb biomass over 44 months. The biomass values we measured were typical or slightly below the average from 11 studies elsewhere in the tropics. Variation in biomass between our neighboring study sites exceeded that between sites on different continents, indicating the sensitivity of vegetation regeneration to local land use. Tree regeneration was extremely slow (0.46 g/m2/year); however, the woody herbs and grasses on a 4 year old fallow of ～0.5 ha can provide much of a family's domestic fuel. Fallow land is generally abundant in western Uganda and can partially alleviate pressure on forests for domestic fuels. Fallows cannot however provide the trees demanded by charcoal, brick, and gin manufacturers. In the future, conserving forests while meeting fuelwood demands will require improving local land tenure security, enhancing the productivity of cultivated and abandoned land, promoting more efficient stoves, stills and kilns, and curtailing illicit, inefficient charcoal manufacture. 相似文献
10.
Emergy Evaluation of Lacandon Maya Indigenous Swidden Agroforestry in Chiapas, Mexico 总被引：3，自引：0，他引：3
The Lacandon Maya of Chiapas, Mexico practice a system of swidden agroforestry that mimics the surrounding ecosystem and its
successional stages. Their fields rotate through grass (milpa), and shrub (acahual) and forest fallow stages that regenerate
soil, nutrients, and seed banks. Each successional stage, including the fallow stages, produces over 25 types of crops, raw
materials, and medicines. Lacandon traditionally do not use fertilizers, pesticides or herbicides. An emergy evaluation of
Lacandon agroforestry was conducted to quantify resource use, productivity, environmental impact, and overall sustainability.
Six systems were analyzed. The Emergy Yield Ratios of the systems ranged from 4.5 to 50.7, which indicated a high level of
output per purchased investments. The agroforestry systems had minimal environmental impacts as shown by Environmental Loading
Ratios between 0.03 and 0.38. The Emergy Sustainability Index (ESI) of the systems ranged from 12 to 1740, indicating a high
level of sustainability. The high ESI values were partially due to a large fraction of renewable resources that varied from
0.72 to 0.97. ESI was dependent upon land area devoted to the system for each family, where greater land area resulted in
higher values of ESI. Labor invested did not exhibit a direct effect on sustainability. 相似文献
11.
《Journal of Sustainable Forestry》2013,32(1-2):93-113
Abstract The use of fire in the La Amistad Biosphere Reserve, Panama, is a complex issue, especially given its biophysical, cultural, and socioeconomic context. A geographic gradient exists, depicting the threat from fire to the reserve. Areas around Volcan Baru have a high potential fire threat due to the biophysical aspects of the area and land-use activities. Fire use has a long cultural history in Panama. It continues to be frequently employed to clear land for swidden agriculture, cattle ranching on the Atlantic side of the Talamancan mountain range, and agricultural development on the Pacific side. Land tenure insecurity and perverse policies also incite its utilization for claiming land. Set fires often escape their boundaries and burn property, structures, crops, and fire-sensitive ecosystems. If left unchecked, anthropogenic fires pose a significant threat to both the ecological and socioeconomic well being of the Biosphere Reserve. Recommendations for the reserve's fire management plan focus on policy augmentation, educational outreach, monitoring, prevention, and fire research. 相似文献
12.
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. 相似文献
13.
《Journal of Sustainable Forestry》2013,32(1-2):63-73
Abstract The relationship between forests and agriculture is age old for subsistence living in the Central Himalayan region. The demand for commercial wood is also met from the same forests. The pressure on forests is high, and the consequences are land degradation and downstream impacts. Forest resources should be made accessible at village level for use by villagers, and forestry should be practiced at village level and integrated with agriculture. However, there are several constraints that forestry may be a solution, due to greater productive and protective values of trees in the Central Himalayan region. 相似文献
14.
Jamie N. Cotta Karen A. Kainer Lúcia H.O. Wadt Christina L. Staudhammer 《Forest Ecology and Management》2008,256(1-2):28-35
Brazil nut (Bertholletia excelsa), has emerged as the cornerstone of the extractive economy in much of the Amazon, but the debate continues as to whether or not current harvest levels have a detrimental effect on Brazil nut seedling recruitment. While regeneration studies to date have been conducted solely within mature forest, our study provides further insight into current Brazil nut regeneration dynamics, with a unique first look at regeneration in swidden fallows within two multiple-use areas in Acre, Brazil. Recruitment of individuals ≤10 cm diameter at breast height (dbh) was evaluated within three 9 ha mature forest plots and six fallows of 0.5–1.0 ha each. Higher mean densities of B. excelsa seedlings (individuals <1.5 m in height) were observed in fallow than in mature forest (12.7 and 5.3 individuals ha−1, respectively). A generalized linear mixed model analysis revealed that in addition to forest type, proximity to seed sources also explained seedling densities. Height and diameter growth of young B. excelsa individuals was positively related to light availability. Photosynthetic photon flux density levels were over three times higher in fallows versus mature forest during peak sunlight hours. Results suggest that fallow environments may provide favorable conditions for B. excelsa regeneration. Not only can anthropogenic disturbance in the form of shifting cultivation play a positive role in B. excelsa regeneration, its historic presence on the landscape could explain current Brazil nut densities and distributions. Finally, swidden fallows could potentially be managed for enhanced Brazil nut densities, which may provide an opportunity for greater income for extractive families while contributing to the sustainability of Brazil nut extraction and forest conservation in the long term. 相似文献
15.
Charles Staver 《Agroforestry Systems》1989,8(2):173-196
In the Palcazu Valley alluvial Inceptisols are relay-cropped with maize-cassavaplantain in rotation with 2–5 years of tree
fallow. These lands, of limited extent, yet important for Yanesha Indian subsistence production, are being cropped even more
intensively as population increases and land is converted to other uses. The relay-planting of the tree-thicket combination
Inga edulis with Desmodium ovalifolium into the on-farm crop sequence was evaluated as a means to accelerate fallow recovery and thereby shorten fallow rotations.
Three experiments with Inga/Desmodium planted with cassava-plantain and one with rice under different weeding regimes after a Desmodium fallow were conducted. Inga and Desmodium were not chopped back or pruned during these experiments. Desmodium/Inga suppressed herbaceous weeds from one year after planting. Desmodium/Inga accumulated more woody biomass than natural fallows. Cassava yields were unaffected by the presence of Desmodium/Inga, while plantain yields were greater under Desmodium/Inga compared to natural weeds. Desmodium/Inga, while promising for shortening fallow rotations, demonstrated potential difficulties: increased labor for establishment,
tendency of Desmodium to weediness in later crop cycles, and suppression of the natural regeneration of trees and shrubs. 相似文献
16.
Personal preferences and intensification of land use: their impact on southern Cameroonian slash-and-burn agroforestry systems 总被引：1，自引：0，他引：1
Douglas R. Brown 《Agroforestry Systems》2006,68(1):53-67
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. 相似文献
17.
滇西边缘山区传统农业的变化及其动因分析 总被引：1，自引：0，他引：1
面对20世纪80年代初我国农村实行土地联产承包责任制以来,云南山区传统农业发生极大变化的态势。通过实地调查及分析,揭示了滇西边缘山区自该年代以来传统农业发生变化的实况,综合分析了6个外部动因和两个内部动因对当地传统农业变化所起的作用,并简析其变化对该地区物种多样性的影响。结果表明:在宏观农地类型上,20世纪80年代初轮歇地的几近消失为最显著变化,主要动因为国家政策和人口、劳动力、生计手段。在微观农地田野类型上,园地和混农林有较快变化,主要动因为市场价格,政府导向,改良品种的引进和推广。此外,引起该地区农地变化的内外动因还有自然土壤条件的退化,发展需求和传统农业知识。 相似文献
18.
利用土地生产模型模拟尼泊尔的森林破坏(英文) 总被引：1，自引：0，他引：1
本文利用土地生产模型基于人口增长率、国民生产总值增长率和农业生产率的增长率来 预测尼泊尔国家,Chitwan地区,Jutpani村的森林破坏的面积与趋势。在研究中如果上述各项 增长率保持目前水平不变，通过土地生产模型的模拟，研究区域的所有林业用地将以每年24 %的速率在2038年全部变为农业用地；假设自给作物生产率每年按1%增长，经济作物按2%增 长，则每年林业用地转换为农业用地的速率降低为17%，但到2038年可能只留有124公顷的森 林。因此农业生产率是影响森林破坏的主要因素，加强农业管理极为重要。 相似文献
19.
Nur Muhammed Md. Farhad Hossain Masum Md. Mohitul Hossain Sheeladitya Chakma Gerhard Oesten 《林业研究》2013,24(3):591-597
Homestead forests contribute substantially to the rural economy of Bangladesh. Rural people depend on trees and plants for their energy usage, housing, food and other forms of subsistence livelihood. In order to identify the potential role of forests on homestead dwellers, an empirical field investigation was conducted in the four Upazilas of Mymensingh district of Bangladesh. It was found that land holdings of the respondents within the four sites are the highest in Mymensingh. The study made an important observation that among all homestead vegetation between 5–6 years old, tree species are generally preferred over plants. This is perhaps due to the efforts of the social forestry extension service to demonstrate that planting trees is an important long-term investment. In all four Upazilas, there was a significant correlation between household annual income and homestead forestry, agriculture and fisheries practice, suggesting that higher income families tend to have larger holdings of homesteads, farms and pond areas. Three Upazilas displayed a strong positive relationship (nearly 45%) between homestead forest areas and annual family income; however, the Fulbaria Upazila showed a very poor relationship (0.2%) in this regard. The results of this study suggest that homestead forests play a positive role in the rural economy, in addition to helping mitigate the increasing problem of deforestation in Bangladesh. 相似文献
20.
Erika Styger Erick C. M. Fernandes Harivelo M. Rakotondramasy Eric Rajaobelinirina 《Agroforestry Systems》2009,77(2):107-122
Soil fertility restoration depends on natural fallows in the slash-and-burn system of eastern Madagascar. In the Beforona-Vohidrazana
study zone, none of the fallow species are able to withstand the slashing, burning and cropping frequencies of 3–5 years.
Eventually soils are abandoned for agriculture. Along the degradation sequence, this study quantifies fallow biomass, nutrient
stocks and soil nutrient availability of four dominant fallow species Trema orientalis, Psiadia altissima, Rubus moluccanus, and Imperata cylindrica. At 3 years, the shrubs Psiadia and Rubus were more productive (11–14.4 t/ha aboveground biomass or AGB) than the tree species Trema (8.5 t/ha). Only after 5 years did tree productivity (24.7 t/ha) exceed that of shrubs (17–20 t/ha). Imperata’s biomass stagnated at 5.5 t/ha after 3 years. A sharp decline in fallow productivity was observed with advancing fallow
cycles after deforestation. While Psiadia produced highest AGB in the second fallow cycle (C2) being 100%, C1 achieved 89% of that, C3 74%, and C4 only 29%. With the
ability to propagate vegetatively and to accumulate important amounts of nutrients in roots, Rubus and Imperata, both exotic and invasive species, showed improved adaptation mechanisms towards frequent disturbances compared to the two
indigenous species Trema and Psiadia. Available soil nutrients P, K, Mg were highest under forest and declined rapidly with increasing fallow cycles. Ca and pH
rose momentarily in the first fallow cycle before declining with advanced soil use. Al concentrations increased steadily with
time. As lengthened fallow periods are not practical, there is a need to intensify upland systems based on improved nutrient
cycling, targeted inputs, fire-less land management, and land use diversification. Allowing regrading tree and bush fallows
to accumulate biomass (above- and belowground carbon) will significantly improve Madagascar's greenhouse gas mitigation contribution. 相似文献