Swidden Fields Research Articles

Open-Access Archaeological Predictive Modeling Using Zonal Statistics: A Case Study from Zanzibar, Tanzania

This paper presents a case study using zonal statistical analysis for archaeological predictive modeling with open-access software and free geospatial datasets. The method is applied to the rural landscapes of Zanzibar, Tanzania on the Swahili Coast. This study used QGIS (version 3.28) to perform zonal statistical analyses of environmental datasets weighted by settlement classes digitized from a 1907 historical map, to create predictive models for settlement across the island. These models were compared against the locations of major precolonial archaeological sites on the island and site data from a random stratified archaeological survey in an environmentally diverse region of northern Zanzibar. The results show strong correspondences between larger permanent site locations and areas of high likelihood for site detection in the predictive model. Additionally, there were correspondences between areas of lower likelihood for site detection and smaller, ephemeral sites related to agricultural production in swidden field plots. These results attest to Swahili rural complexity and enable an understanding of the specific environmental affordances that structured settlement and land use over the last millennium, in ways that shaped colonial contact in rural areas and altered the sociopolitical development of Zanzibar and the East African coast. The methods described here may be applicable for researchers and heritage managers in Africa and the Global South, where funding for large-scale field projects, expensive satellite imagery, or software licensing is limited.

Soil fertility in indigenous swidden fields and fallows in northern Amazonia, Brazil

AbstractIn the northern Brazilian Amazon, indigenous peoples who inhabit the savannas of Roraima, plant their crop fields in frequently managed “forest islands” using a rotating “slash‐and‐burn” system. The system advocates long‐term sustainability, but population growth and threats to indigenous lands have led to shorter rotations and greater frequency of use of forest island areas. Our objective was to examine soil texture and fertility (0–20 cm in depth) in indigenous crop fields (roças) and fallow lands (capoeiras, secondary forests), generating recommendations that may help to optimize traditional soil management. Results indicated that roça sites are less acidic than capoeira sites, which was expected as ashes produced by burning are alkalizing, but acidity did not increase again after 8 months of cultivation, and pH was high in all sites (>6). The general increase in nutrients expected in roças compared with capoeiras did not occur. The expected decrease of soil fertility after first months of cultivation did not happen, nor the increase of soil fertility according to fallow length. Overall, soil texture proved to be the main determinant of fertility. The unexpected results suggest that the edaphic processes resulting from the traditional indigenous cultivations, practised for centuries or millennia in this region, likely contributed to the current stabilization of soil acidity and fertility. The stable moderate fertility and stable high pH observed in all sites are advantages for production in slash‐and‐burn systems in this region, and this is especially important for more pressured areas, where agroecological practices could improve soil use and management. Although not determinant for soil fertility recovery at the studied depth (0–20 cm), the fallow period (growth of capoeiras) is still important for recovery of environmental and social functions of forest islands.

Using locally available fertilisers to enhance the yields of swidden farmers in Papua New Guinea

ContextSwidden agriculture (a type of small-scale agriculture) is crucial to the livelihood and food security of millions of people in tropical regions. Social-ecological changes, including population growth and anti-swidden policies, are putting pressure on the existing swidden system to increase agricultural productivity in a sustainable way. Enhancing soil fertility is a promising option for increasing crop yields and extending lifetimes of agricultural fields, thereby reducing the demand to clear new land. However, there is limited information on how swidden farmers can best maintain soil fertility. ObjectiveOur aim was to investigate whether using locally available fertilisers can increase soil quality, crop yields and lifetimes of swidden fields. MethodsWe established experimental gardens on the land of swidden farmers in the Lowlands of Papua New Guinea, where the majority of the population depends on swidden agriculture. Gardens were set up on two types of sites; five were established on new sites that had just been prepared for gardening by cutting and burning vegetation after a fallow period, whereas another five were prepared on garden sites that were just being fallowed. We applied three treatments; i) compost consisting of decaying banana peels, ii) chicken manure, and iii) NPK fertiliser to different plots within each garden; and tracked soil quality and yields of sweet potato over 12 months (three post-intervention cropping periods). We also conducted in-depth interviews with local farmers to understand their perspective on soil management. Results and conclusionsFew farmers typically used compost, chicken manure or NPK fertiliser. Many were keen to try these fertilisers, provided they had more information. The performance of treatments depended on the type of garden with chicken manure increasing tuber yields in fallowed gardens but not new gardens, and banana peel compost also increasing tuber yields in fallowed gardens although not significantly. NPK fertiliser was the best option because it was the only fertiliser that increased yields in both new and fallowed gardens, produced tubers of similar quality and taste to control plots and was financially profitable. Treatments affected yield through increasing available nitrogen and reducing soil moisture. We also found that farmers fallow their gardens despite adequate sweet potato yields, so whether using fertilisers can enhance the lifetime of fields will depend on additional factors such as labour input needed. SignificanceOur work shows how swidden agriculture can potentially be adapted so that it continues to be a sustainable way of farming and living.

Political violence, migration, lack of citizenship, and agrobiodiversity loss in the borderlands of Thailand and Laos

In the 1970s and 1980s, the borderlands between southern Laos, northeastern Thailand and northern Cambodia were a hotbed of militarized conflict and insurgent activity. Various armed groups, on the political left and right, operated in what was later referred to as the Emerald Triangle. This article considers how ethnic Kuy (Souay) Indigenous peoples from the Lao side of the border in Mounlapoumok District, Champasak Province, southern Laos, fled to neighboring parts of Ubon Ratchathani Province, northeastern Thailand as political refugees after Pathet Lao communists took over Laos in 1975. Many later became stateless insurgents fighting for Lao anti-communist groups opposed to the Lao People’s Democratic Republic. In particular, the article considers the influence of political armed conflict on migration and citizenship status, and subsequently on agrobiodiversity loss, particularly of native varieties of upland rice cultivated in swidden fields. This includes considering the structural violence associated with Thai government policies and practices related to forest conservation and preventing swidden cultivation. Agrobiodiversity loss was not centrally influenced by political violence, but it significantly influenced the conditions that affected agrobiodiversity, emphasizing the potential usefulness of studying political violence and agrobiodiversity loss through considering indirect influences.

Access mapping highlights risks from land reform in upland Myanmar

ABSTRACT Secure land access is vital for Myanmar’s upland households, who rely on crops and forests to meet their subsistence needs. But recent land reforms threaten to undermine customary tenure and land-use practices in Myanmar. This paper combines income accounting methods with access theory to assess how new legislation may affect four Chin communities in the country’s north-west. Our assessment of 94 households’ land-access mechanisms and economic benefits from different types of land reveals existing land-access inequalities among Chin households and demonstrates communities’ continued dependence on environmental resources, especially those from swidden fields, home gardens and forests. A majority of households would lose all of their land-derived income, if they were denied access to communities’ customarily governed land, e.g., under the Vacant, Fallow and Virgin Land Management Law. Policy stakeholders should therefore intervene, to alleviate land-access inequalities among Chin households and to direct Myanmar’s land-system dynamics onto more just development trajectories.

Before it disappeared: ethnobotanical study of fleagrass (Adenosma buchneroides), a traditional aromatic plant used by the Akha people

BackgroundFleagrass, Adenosma buchneroides, is an aromatic perennial herb that occupies an important position in the life of the Akha people. They regard it as a tribal symbol and a gift of love. Fleagrass also has many medicinal uses, and there is considerable potential for its development as an insect repellent. Traditionally, Akha people plant it in swidden fields, but there are few swidden fields in China now. Therefore, the first question this study aims to answer is as follows: how is fleagrass planted and utilized now? At present, fleagrass is only reported to be used by Akha people in Mengla. We also try to understand the following questions: Is fleagrass used in nearby area? If so, how is fleagrass used in nearby area? Furthermore, why is fleagrass used in that way?MethodsFrom August 2016 to July 2018, field surveys were conducted six times. The ethnobotanical and ethnopharmacological uses of A. buchneroides in 13 Akha villages were investigated by means of semi-structured interviews. We assessed the responses of a total of 64 interviewees (32 men and 32 women; mean age, 58.6) from the Xishuangbanna Dai Autonomous Prefecture, southwest China, and from Phongsaly Province, Laos. To explain the bases for the ethnobotanical uses of fleagrass, we used Google Scholar, Web of Science, and China National Knowledge Infrastructure to review the bioactivities of the chemical constituents of A. buchneroides.ResultsWith the vanishing of swidden agriculture and the development of modern products, fleagrass cultivation is disappearing in China. However, most Akha people in Xishuangbanna still remember and yearn for its traditional uses, and Akha people in a nearby area (northern Laos) continue to plant and utilize it. We documented ten uses of A. buchneroides within five discrete categories. The whole plant of fleagrass has a distinct strong aroma, of which Akha villagers are particularly fond. Akha villagers mostly use this aromatic property as a decoration, perfume, and insect repellent. A. buchneroides is also used as a condiment and for medicinal and ritual purposes, including its use as a cure for insect bites, headaches, influenza, and diarrhoea, and as a part of pray ritual for a bumper harvest. From our literature review, we identified many major chemical compounds contained in the essential oil of A. buchneroides, including thymol, carvacrol, 3-carene, and p-cymene, which have insecticidal or insect-repellent, antimicrobial, and anti-inflammatory properties.ConclusionFleagrass is an aromatic plant that is widely used by Aka people. Its chemical composition also has a variety of biological activities. With the vanishing of swidden agriculture and the development of modern products, fleagrass utilization in China is disappearing and its cultural importance is reduced. However, its economic and medicinal value is assignable.

Recognizing indigenous knowledge of the Karangwangi Rural Landscape in South Cianjur, Indonesia for sustainable land management

Amelia F, Iskandar J, Partasasmita R, Malone N. 2018. Recognizing indigenous knowledge of the Karangwangi Rural Landscape in South Cianjur, Indonesia for sustainable land management. Biodiversitas 19: 1722-1729. Karangwangi is a rural community on the south coast of West Java, Indonesia. The people of Karangwangi possess traditional ecological knowledge (TEK) of local landscapes through cultural inheritance and personal experiences of interacting with their environment. The people of Karangwani Village recognize various natural-cultural landscape types, including leuweung (forest); swidden field (huma); wet rice fields (sawah); home garden (pekarangan); garden (kebun); mixed-garden (kebun campuran); river (sungai); and sea (laut). These various landscapes have continuously changed over time due to people’s socio-economic and cultural activities. The aim of this study was to develop an ethnoecological approach to elucidate historical changes to the Karangwangi landscapes. Toward this aim, we conducted mixed-method, qualitative and quantitative research. In addition to recognizing the various types of cultural and natural landscapes, the local people of Karangwangi are able to describe the history of landscape changes between 1950 to 2017. As identified by informants, these changes have been caused by various factors, including increases in population density, implementation of government policies and village development.

Site selection and soil fertility management by the Outer Baduy People (Banten, Indonesia) in maintaining swidden cultivation productivity

Iskandar J, Iskandar BS, Partasasmita R. 2018. Site selection and soil fertility management by the Outer Baduy People (Banten, Indonesia) in maintaining swidden cultivation productivity. Biodiversitas 19: 1334-1346. The Outer Baduy people heavily depend on swidden cultivation for subsistence. They grow rice in the uplands every year based on their calendar. The cropping calendar and calendar of social events are often closely interlinked. There is also traditional wisdom for conservation of land and forest such as the zonation for land use system. The Outer Baduy swidden land productivity is mainly determined by the time period of forest fallow relative to that of the crops. The long-term success of the Outer Baduy swidden cultivation depends on how well the fallow period restores or maintain soil fertility. The aim of this research was to study the local knowledge of Outer Baduy of soil categories and soil fertility and the management of soil fertility in their traditional practice of swidden cultivation. The method used in this study was the qualitative one, applying observation and in-depth interviews to collect the primary data. In addition, soil analysis was conducted by the Laboratory of Soil, Faculty of Agriculture, Padjadjaran University, Sumedang, Indonesia. The results of this study showed that the soils are classified by the Outer Baduy based on color, water content, stoniness or rock parent material, and humus content. To maintain soil fertility in the swidden cultivation, the Outer Baduy people have developed some strategies, such as determining appropriate fallow time period, applying zero tillage, and planting legume crops in both the swidden fields and the fallow land. Traditionally, because the Outer Baduy are forbidden to use inorganic fertilizers, the length of fallow period and kind of vegetation succession have an important role in maintaining soil fertility.

パーリア族の焼畑耕地とその造成技術 : インド半島北部の焼畑農耕民の農業技術に関する調査報告その 1

パーリア族の焼畑耕地とその造成技術 : インド半島北部の焼畑農耕民の農業技術に関する調査報告その 1

A correlation between the increased temperatures and the productivity of ladang in Kutai Barat Regency, the province of east Kalimantan, Indonesia

The studies on the impact of global warming, particularly in the field of food production, could provide more accurate analysis to support a policy of food security. This research was conducted to find out the trends and the impact of the increase in the air temperature on the production of ladang (swidden field) in the Kutai Barat Regency. The results of the research carried out in some of the traditional rice fields indicate a technology that has barely changed, and organic based cultivation. During the period 1990?2015, air temperature increased leading to daily average of 21.2?C?25.2?C or an average increased by 0.16?C/year. In the same period, the productivity of ladang increased by 1.872?3.195 kg ha-1 or an average increased by 261 kg/hectare/year. Linear regression analysis results at the 5% level of significance showed the existence of the real correlation (r=0.7) between the average air temperature change and the productivity of the paddy fields.

A Nutrient Balance Analysis of the Sustainability of a Composite Swiddening Agroecosystem in Vietnam's Northern Mountain Region

This paper reports some results of the first three years of an on-going research project on nutrient balances in a composite swidden agroecosystem. In a composite swiddening system, households simultaneously cultivate both swidden fields on hill slopes and paddy fields in the valleys. The study is being carried out in Ban Tat, a small settlement of Da Bac Tay ethnic minority people in Hoa Binh Province in Vietnam’s Northern Mountain Region. Nutrient inputs and outputs for a swidden field on a hill slope and a wet rice field in the valley below it were recorded and nutrient balances for each subsystem calculated. The swidden had large negative balances for N, P, and K in all years of the experiment whereas in the paddy field only K was in serious deficit. Nutrients lost from the swidden field constituted a major source of inputs into the paddy field. This suggests that the sustainability of wet rice agriculture in the valleys is heavily dependent on interactions with the hill slopes. At the level of the composite swidden system as a whole, nutrient inputs and outputs were not in balance. Outputs of N exceeded inputs by 159 kg/ha and outputs of K exceeded inputs by 867 kg/ha. Only P showed a positive balance with inputs exceeding outputs by 220 kg/ha. Comparison of the nutrient balances for the swidden and the wet rice field revealed that the negative imbalance of nutrient inputs to outputs was much greater in the swidden field than in the paddy field. Thus, if the farmers at Ban Tat relied exclusively on swiddens to meet their food requirements, their agricultural system would be much less sustainable than it is now. This confirms the main hypothesis of this research that it is the fact that most households simultaneously cultivate both wet rice fields and swiddens that explains the relatively high sustainability of the land use system in Ban Tat.

Underground biomass accumulation of two economically important non-timber forest products is influenced by ecological settings and swiddeners’ management in the Bago Mountains, Myanmar

Diverse tree species, understory bamboos, shrubs, and herbs in mixed deciduous forests (MDFs) provide not only timber, but also non-timber forest products (NTFPs) in terms of fuel, food, and medicinal plants. Sustainability and the economic value of commercially extracted NTFPs have been studied mainly for the aboveground vegetative components of plants. However, such important knowledge of the underground parts of the plants is limited because of difficulties observing them and lesser consideration of the lower value of NTFPs, compared with timber, in forest management. Here we established allometric models to predict the root and corm biomasses of two plants, Rauvolfia serpentina and Amorphophallus bulbifer, in relation to their aboveground, vegetative parts. Estimated underground biomasses of the two species were compared among three habitat types: a swidden field, a fallow forest after cultivation, and a ridge forest that was not subjected to swidden agriculture. The length of the longest leaf of each individual plant explained the accumulation of the underground biomass of R. serpentina (R2=0.64, P<0.001) in a positive, linear relationship, and stem diameter at ground level did the same for A. bulbifer (R2=0.92, P<0.001). The largest biomass accumulation of R. serpentina was found in swidden fields because of its light demanding nature, which was supported by a significant, negative correlation between canopy cover and leaf length (Pearson’s correlation=−0.612, P<0.05). Because A. bulbifer was cut during weeding time, we could not measure its biomass accumulation in swidden fields; however, its occurrence in swidden fields was confirmed by farmers and field observations. No difference in the biomass accumulation of A. bulbifer was observed between the fallow and ridge forests. The promising growth of both species in the same year that a fire occurred during swidden cultivation suggests that the underground regeneration source provides advantages related to the harvesting of NTFPs and allows them to co-exist with slashing and burning in a swidden system, as well as surface fires in an MDF. Establishment of the two species in fallow vegetation was possibly facilitated by ecological and anthropogenic factors such as the reproductive bulbils of A. bulbifer and the broken root fragments of R. serpentina left after the harvest, as well as the dormancy period of these species during the dry season. This study revealed the cultivation potential of NTFPs that are suitable for community and agroforest plantations using a swidden system in an MDF that experiences fires.

Plastic landscapes, plastic identities: Akha identity on the threshold of definition

In his study of communities in upland Southeast Asia, James Scott cites the practice of shifting cultivation as being reflective of state evasion. The Akha tribe of Northern Thailand destabilises this correlation, and demands a more nuanced notion in which identity is actively negotiated between state intervention and traditional landscape plasticity. While historically employed as a method of state evasion, shifting agriculture has become enmeshed in Akha ritual performance as a signifier of identity. While Scott claims that shifting agriculture implies a divorce from state interaction, the Akha employ subversive agriculture techniques and adopt state policies according to highly localised conceptions. According to Forsyth and Michaud, hill people capitalise upon their capabilities within a shifting political and economic context—with the Akha adopting a system of composite swiddening and invisibly subverting state land use policies. Under a system Janet Sturgeon conceptualised as ‘landscape plasticity’, forests can become swidden fields and then revert back to forests as the Akha assert their agency to sustain mutable landscapes that incorporate both present and future use. Thus, the Akha negotiate boundaries of topography and modernity to subvert state intervention and adopt a plasticity of landscape and identity.

FIRE MANAGEMENT IN VEREDAS (PALM SWAMPS): NEW PERSPECTIVES ON TRADITIONAL FARMING SYSTEMS IN JALAPÃO, BRAZIL

Abstract The veredas (palm swamps) of the cerrado biome are legally protected as Áreas de Preservação Permanente (Permanent Preservation Areas), and the use of fire in these wetlands is prohibited. We carried out a preliminary assessment of environmental impacts of the local use of agricultural fire in veredas through a collaborative research project in Jalapão (Tocantins, Brazil). We found that "roças de esgoto" (drained peat swamp swidden fields) form the basis of the agricultural system of this region. These fields ensure production throughout the year, provide more income than "roças de toco" (rainfed swidden fields), and may function as a repository of agrobiodiversity on a regional scale. This study suggests that the use of fire in veredas associated with roças de esgoto does not lead to significant deforestation, that is, to the disappearance of the forest physiognomy, but instead helps maintain tree cover during the fallow period, possibly accelerating natural succession.

The Effect of Fallow Period Length on the Abundance and Diversity of Usable Plant Assemblages in Shifting Cultivation System (Swidden Agriculture) in Northern Laos

ABSTRACT Shifting cultivation, or swiddening, involves alternating cycles of cropping and fallow periods. Rather than being abandoned, the fallow swidden fields provide a source of important plant products for remote, forest-dwelling human communities. In northern Laos, the traditional length of fallow periods used to range between five and 11 years, depending on the availability of land and quality of the soil. Fallow periods are currently being shortened because of population pressures and government policies. To determine the potential impacts of shorter fallow periods, 128 swidden fallows of various ages (up to 20 years), located at altitudes between 400 and 800 m a.s.l. in northern Laos were sampled for usable plants. The impact of fallow length on plant abundance and species diversity was analysed. The number of usable plant species was found to increase with the fallow age until it was 11–12 years old, and then decline, while the abundance of usable plants increased beyond that period. We conclude ...

Capitalizing on Compensation: Hydropower Resettlement and the Commodification and Decommodification of Nature–Society Relations in Southern Laos

Compensation programs for hydropower dam resettlement have far-reaching effects, including restructuring nature–society relations in support of capital accumulation. Although critical scholarship has shown the structural limitations of compensation programs for reducing poverty after resettlement, here we draw on the specific case of the Xepian-Xenamnoy hydroelectric dam project in the Xekong River Basin in southern Laos to explore the transformation of nature–society relations among the Heuny people. We argue that the compensation processes of valuation, abstraction, and privatization of property relations have contributed to the variegated commodification of land and other natural resources used by the Heuny. In contrast to arguments that capitalist expansion leads to ever increasing commodification, however, we demonstrate that compensation variously decommodifies other natural resources, such as certain nontimber forest products and wild fisheries, keeping other things, such as swidden fields and forest land, noncommodified. Moreover, these processes of variegated commodification are spatially variable, largely dependent on Heuny conceptions of space, thus affecting the commodification of land and other natural resources. Ultimately, by linking compensation to processes of (de)-commodification in its various forms, we suggest new ways in which capitalist social relations are being transformed and expanded through hydropower-induced resettlement. Furthermore, we call into question the ability of material compensation to restore previous livelihood and environmental conditions, as changes brought on by the compensation process itself have much deeper and profound implications when it comes to nature–society relations.

Monitoring the spatio-temporal dynamics of swidden agriculture and fallow vegetation recovery using Landsat imagery in northern Laos

Swidden agriculture is an age-old, widespread but controversial farming practice in Montane Mainland Southeast Asia (MMSEA). In the uplands of northern Laos, swidden agriculture has remained a predominant human-dominated land-use type for centuries. However, swidden system has undergone dramatic transformations since the mid-1990s. Debates on changes in swidden cultivation are linked to globally critical issues, such as land use/cover changes (LUCC), biodiversity loss and environmental degradation. Since the implementation of Reducing Emissions from Deforestation and Forest Degradation (REDD), much attention has been paid nationally and internationally to swidden agriculture in the tropics. However, knowledge of the explicitly spatial characteristics of swidden agriculture and the consequences of these transitions at macroscopic scale is surprisingly scarce. In this study, the intensity of swidden use and fallow forest recovery in northern Laos in 1990, 2002, and 2011 were delineated by means of Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper plus (ETM+) imagery (30 m) using a decision tree classification approach, followed by an analysis of the spatio-temporal changes in swidden agriculture. Next, annual successive TM/ETM+ images during 2000–2010 were used to delineate the dynamics of the burning and cropping phase. Subsequently, the burned pixels identified in 2000 were compared respectively with their counterparts in the following years (2001–2011) to investigate temporal trends, land-use frequency, and the swidden cycle using time-series Landsat-based Normalized Difference Vegetation Index (NDVI) data. Finally, as the swidden cycle changed from 1 to 11 years, the fallow vegetation recovery process was studied. The results showed that: (1) from 1990 to 2011, the area of swidden agriculture increased by 54.98%, from 1.54×105 ha to 2.38×105 ha in northern Laos. The increased swidden cultivation area was mainly distributed in Luang Prabang and southern Bokeo, whereas the decreased parts were mainly found in Phongsali; (2) swidden agriculture increased mainly at elevations of 500–800 m, 300–500 m, and 800–1000 m and on slopes of 10°–20° and 20°–30°. Over 80% of swidden fields were transformed from forests; (3) during 2000–2011, the frequency of swidden use in northern Laos was about two or three times. The interval between two successive utilization of a swidden ranged from one to seven years. Comparison of swidden cycles and the related proportions of swidden farming in 2000, 2003, and 2007 revealed that swidden cycles in most areas were shortened; and (4) there was a significant correlation (0.97) between fallow vegetation recovery and the swidden cycle. The NDVI of regenerated vegetation could approach the average level of forest when the swidden cycle reached 10 years.

Genetic structure and diversity in the Dioscorea cayenensis/D. rotundata complex revealed by morphological and isozyme markers

Of the 600 known yam species, only 10 are utilized as food, and the Dioscorea cayenensis/D. rotundata species complex is among the most cultivated. In Brazil, these species are commercially cultivated in the northeast region and are cultivated in the south and southeast regions as subsistence crops by traditional agriculturists. This study aimed to evaluate the genetic diversity of 21 local varieties of D. cayenensis and 2 D. rotundata accessions using 7 isozymic loci and 24 morphological markers, and to investigate the diversity distribution in different levels of organization, such as swidden fields and communities of Vale do Ribeira. Cluster analyses for both the isozymic and morphological data separated the 2 D. rotundata accessions from the D. cayenensis accessions from Vale do Ribeira. The analysis with morphological characteristics showed the presence of 2 subgroups (Iguape and Cananéia) within group I, which included all of the local varieties from Vale do Ribeira; this result may indicate the influence of the cultural units on the morphological variation. Molecular analysis of variance indicated that most of the isozymic variability was concentrated among swiddens within communities (42.5%) and within communities (40.3%). Most of the morphological variability was also concentrated among swidden fields within communities (44.8%). The correlation between geographic and genetic distances indicated that neither morphological (r = 0.17) nor isozymic diversity (r = -0.15) is structured in space. Thus, the traditional agriculturists of Vale do Ribeira maintain and manage a great diversity of D. cayenensis varieties in their communities.

Is There a Continuing Rationale for Swidden Cultivation in the 21st Century?

Large areas of the tropical forest landscapes are still occupied – partly or fully – by swidden cultivation, but it is also clear that in many areas both the extent and intensity of swidden cultivation are changing. This is not new as it has always been a dynamic system used when it is opportune and changed or even dropped when other more favorable options for land and labor use, income, etc. appear. It seems that these changes now occur faster in some regions and slower or not at all in others (van Vliet et al. 2012). Political and economic pressures are the main drivers that have encouraged or enforced such changes, particularly towards more intensive agricultural practices or to other types of land use (urbanization, large scale plantations, protected areas, extractive concessions, etc.). However, the nature of these changes in swidden cultivation are not well documented, partly because swidden fields and the various successional stages of woody re-growth associated with it are often categorized as ‘unclassified’ or ‘degraded’ land or lumped together with other land cover categories (Padoch et al. 2007; Schmidt-Vogt et al. 2009). Swidden cultivation is a smallholder category that government authorities find difficult to quantify because it forms part of a complex and diversified production system, together with other multiple small scale land use types (Gleave 1996; Padoch et al. 2007) and there is also little political interest in understanding the logic inherent to swidden cultivation and to quantify the number of people dependent on swidden as they are usually not a desired category of farmers to have appearing in official statistics (Mertz et al. 2009a). It is obvious that if such basic information is unavailable, planners and policymakers have no sound basis for decisions on land use and development in the poorest regions of their countries. In 2009, as a response to the lack of information on swidden cultivation, a special issue was published in Human Ecology providing a comprehensive and mainly literature based overview of swidden cultivation in Southeast Asia (Mertz et al. 2009b). Some of the articles highlighted the problem of defining and measuring the spatial and demographical extent of swidden (Mertz et al. 2009a; Messerli et al. 2009; Schmidt-Vogt et al. 2009), others addressed the drivers and impacts of swidden change by analyzing the political economy of swidden and the implications of swidden transformation for rural livelihoods (Cramb et al. 2009; Fox et al. 2009), and a final set of articles addressed the impacts on the environment of swidden cultivation as well as of the systems that are replacing swidden cultivation (Bruun et al. 2009; Rerkasem et al. 2009; Ziegler et al. 2009). That special issue settled a number of questions about swidden cultivation in Southeast Asia, but also raised a number of other concerns. Indeed, despite a relatively large number of case studies from that region, the knowledge of swidden cultivation is still very patchy and many essential elements such as exact areas under swidden management, the number of persons involved, and the livelihood and environmental consequences of swidden transformations remained only partially N. Van Vliet :O. Mertz (*) : T. Birch-Thomsen Department of Geosciences and Natural Resource Management, University of Copenhagen, Oster Voldgade 10, 1350 Copenhagen K, Denmark e-mail: om@geo.ku.dk

Facilitation of forest landscape restoration on abandoned swidden fallows in Laos using mixed-species planting and biochar application

The cessation of swidden cultivation and the increasing trend of abandonment of swidden fallows have created an opportunity for forest landscape restoration. However, ways need to be found to improve the poor soil fertility at these sites with affordable materials and to generate short-term socio-economic benefits for small-scale swidden fallow holders. This study assessed the feasibility of using mixed-planting of eight native species and application of rice husk biochar as soil amendment measure at a site in Laos. The effect of biochar application was compared against addition of inorganic (NPK) fertilizer and the control. The establishment and growth of the planted seedlings was then monitored for four years. The addition of rice husk biochar and NPK fertilizer did not significantly (p = 0.578) improve the survival rate of planted seedlings, which ranged from 72% to 91% (depending on the species) compared to the control. No significant growth responses to the soil amendments were observed for most of the species during the first year after planting compared to the control. The biochar effect was, however, more evident at the fourth year for diameter (p &lt; 0.01) and height (p &lt; 0.01) of sapling for all species; particularly its effect was more vivid on the diameter of slow-growing species. The results indicate that the species tested in the mixed-planting showed marked growth variation while application of rice husk biochar boosted their growth. Thus, planting mixed-species in swidden fallows has potential to provide continuous supplies of wood from different species to diversify the livelihood of swidden field owners, while maintaining ecosystem services.