Areas in which shifting cultivation can be assumed to have never existed or disappeared decades ago have been excluded from the analysis (dark gray). Intensive agriculture has dominated the global food production . The climate of most European countries is wet Disadvantages of Shifting cultivation: Deforestation Loss of fertility of a specific site Soil erosion Tree burning generates air pollution. It received 1 point in More widespread signs of shifting cultivation were found mostly in small pockets, with the exception of larger areas in Central Africa (e.g. - Myanmar: Shifting cultivation is estimated to mostly disappear sometime between 2060 and 2090 if conflicts between union government and ethnic armed groups are resolved. Its authors detected changes in what they call the rural complex for the period from 2000 to 2010. No, Is the Subject Area "Agriculture" applicable to this article? The five classes corresponded to the following rough ranges of area shares of shifting cultivation landscapes (currently cultivated fields plus all stages of fallows) within an entire one-degree cell: none: < 1%; very low: 19%; low: 1019%; moderate: 2039%; high: 40%. Using the mean values of the ranges specified for the different occurrence classes for all cells in all classes results in a total area of 280 Mha. This has led to a paucity of global information on certain land use systems, including shifting cultivation at the global level. However, there are a number of other negative effects related to irrigation. Extreme precipitation events can disturb plant growth, particularly in recently burned forests, and make plants more vulnerable to flooding and soils to erosion. The selection process ensured that all are experts in the field, but there may be disciplinary or personal differences in the way that especially the future of shifting cultivation was assessed. The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more commonly, when the field is overrun by weeds. However, adequate prediction of land usebased emissions requires an improved understanding of megatrends in land use systems change [2,5]. This became particularly evident when Hurtt et al. Conceptualization, Shifting cultivation systems are commonly associated with rural poverty and forest degradation. (Fig 2DA) and (Fig 2E): The white line grid marks the 1/100 degree cells used as basic unit for the validation data. For each grid cell, the occurrence of shifting cultivation declined linearly by the mid-point of the estimated losses in 2030, 2060 and 2090 (see Section 3.4). Investigation, Large forest or vegetation areas are cleared and burned down for mining operations. However, the areas indicated for each country vary greatly depending on the source. After being used to grow a variety of crops for a year or two, the area is allowed to lie fallow for a period of rejuvenation, while the farmer moves on to a . To assess published scientific material on the current extent of shifting cultivation, we searched the Web of Science (All Databases) using the following search string: [Title]: "shifting cultivation" or swidden* or "slash and burn" or "slash-and-burn" or "shifting agriculture" AND [Year published]: 20052016. In fact, they should be understood as best guesses about general patterns rather than temporally and spatially accurate predictions, as land use transitions often happen suddenly, causing abrupt changes over large areas [23]. 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. The validation of the estimation of landscapes showing signs of shifting cultivation revealed that 95.1% of the one-degree cells showing signs of shifting cultivation in the validation data correspond to the results in our classification. For example, the large areas of tree plantations established in Vietnam and southern China in the 1980s and 1990s can also leave a mosaic signature at a certain point in time and might therefore be incorrectly interpreted as shifting cultivation (Fig 1). Any change in the climate of an area can affect the plants and animals living there, as well as the makeup of the entire ecosystem. Cultivation (tillage) is a practice that has been introduced to Australia from Europe by our farming pioneers. 2.2). In such environments it may be preferable to cultivate a field for a short period and then abandon it before the soil is completely exhausted of nutrients. Spencer [45] indicates an approximate area under shifting cultivation (currently cultivated fields plus all stages of fallows) of around 110 million hectares (Mha) for Asia. asked to explain two reasons why shifting cultivation is expected to decline in the future. It coincided with the end of the last ice age and the beginning of the. Flooding, changing seasons and other weather changes impact the growing seasons of specific crops and could cause more and more damage to outdoor crops, driving some food production indoors and spiking prices at the same time. It ensures the forest will recover. At the regional scale, the only number to which we can compare our result is the 110 Mha for Asia estimated by Spencer [45], which is considerably larger than our estimate for this region of approximately 70 Mha. The areas referred to as the rural complex may be used as a proxy for the presence of shifting cultivation. Besides the need to determine the effects of shifting cultivation on land usebased greenhouse gas emission scenarios, there are other important reasons for gaining a better understanding of change in shifting cultivation systems. Writing original draft, archeological studies or historical studies of shifting cultivation in Europe), duplicates, and papers whose authors had deceased in the meantime, 282 papers remained. [1] indicate 110 Mha for this region, but unlike FAO they did not include Mexico in their estimation. This is only the case if, in addition to a pattern of small-scale clearings in the GFC data, a spatio-temporal pattern of different stages of fallow and regrowth is visible in the very highresolution imagery from Bing and Google. Funding: This research was supported by the Institute of Geography and the Centre for Development and Environment (CDE), University of Bern, Switzerland, as well as the Swiss Programme for Research on Global Issues for Development (r4d) supported by the Swiss National Science Foundation (SNSF) and the Swiss Agency for Development and Cooperation (SDC), grant number 400440 152167, the U.S. Dept. There's no doubt about it: the best thing we can do to fight climate change is keep forests standing. After the soil loses its fertility, the land is abandoned and the cultivator moves to a new plot. The principle of cultivation is to turn the soil into a fine tilth to provide the ideal environment for seeds to germinate. Institute of Geography, University of Bern, Bern, Switzerland, This causes degradation of land, soil erosion, etc. For Central and South America, the survey shows a mixed picture, with some areas being quite stable or even likely to experience expansion in the near future, and other areas (e.g. The earlier 15-20 years cycle of shifting cultivation on a particular land has reduced to two or three years now. Climate change will bring more frequent and severe extreme weather events, including extreme precipitation, wind disturbance, heat waves, and drought. [55], citing the Wasteland Atlas [56], estimated the extent of shifting cultivation in the mid-2000s at 5.6 Mha (only area under cultivation), whereas the GLC2000-based estimate is 7.6 Mha [1]. Supervision, The classic studies on shifting cultivation in Africa [4648] do not provide any area data for the continent, and for Central and South America we were unable to find any regional-scale past area estimation. The stratified validation sample design was chosen considering the distribution of the validation samples per occurrence class and the spatial distribution per continents. Laos, Vietnam) over the past 15 to 25 years is not reflected in this comparison. [1], possibly owing to the scale (1-km resolution) of the GLC2000 data sets. - West Africa (Sierra Leone, Liberia, Guinea, Cte dIvoire, Ghana): Shifting cultivation is anticipated to diminish rapidly by 2030 and to largely disappear by 2060 if peace is upheld and there is no major return of Ebola; but if conflicts resurface, shifting cultivation may persist well into the second half of this century. Citation: Heinimann A, Mertz O, Frolking S, Egelund Christensen A, Hurni K, Sedano F, et al. No, Is the Subject Area "Africa" applicable to this article? We estimate the current global extent of shifting cultivation and compare it to other current global mapping endeavors as well as results of literature searches. [24], who in turn had cited Dixon et al. Shining cultivation fields are generally used not more than two years at a lime, after which . The land takes many years to replenish just at the cost of providing yield for 2 to 3 years. (Fig 2B): Location of the one-degree cell of Fig 2C - 2E. The uptick in mosquito-borne diseases, for example, or the rapid spread of roya, an insidious plant disease that threatens our supply of coffee are all indirect consequences of deforestation and global warming. We limited the search to the period from 2005 to 2016 partly because we were interested in the most recent data on the extent of shifting cultivation as a basis for generating a map showing the contemporary situation (around the year 2010); the other reason was that we expected many recent reports on areas under shifting cultivation to rely on previously published data, which would enable targeted backtracking through the literature all the way to the original sources. Meanwhile, the area under shifting cultivation has decreased by 71.22% from 1997 and forest cover has decreased by 4.41% during the period. https://doi.org/10.1371/journal.pone.0184479.t001. This paper presents the causes and consequences of shifting cultivation and its potential land use alternatives. It is important to note that these are indeed very rough possible scenarios and should be seen as expected trends rather than fixed percentages of decline. If the survey provided information about when (i.e. - Shifting cultivation also destroys the habitat of wild animals at large. [17] showed that these regions have experienced marked decreases in shifting cultivation. For example, data for Laos indicate between 2 and over 6 Mha, while more recent figures based on remote sensing (multi-temporal Landsat) for northern Laoswhere the largest share of shifting cultivation in the country is foundare 3.1 Mha [33] and 2.6 Mha [34]. In Asia, we expect that continued rapid economic development and the related changes in agricultural practices and, more importantly, in the economic structure (from the primary to the secondary and tertiary sectors) may cause shifting cultivation to disappear faster than in Africa or the Americas. There is a need to transform shifting cultivation to sustainable intensification. Using the data and approach described above, each one-degree cell was examined visually at various zoom levels (roughly 1:100000 but, if necessary, occasionally at larger scales) to determine whether it showed the very specific spatio-temporal signature of shifting cultivation (see Fig 1). Copyright: 2017 Heinimann et al. While only an approximation, this estimate is clearly smaller than the areas mentioned in the literature which range up to 1,000 million hectares. in the Amazon and parts of the Democratic Republic of the Congo), or a residual form of cultivation in landscapes that have mostly been transformed to other land uses (such as permanent agriculture or tree crops, e.g. Yes The map shows that shifting cultivation is still present across large areas of the humid tropics. Since there have been many controversies about the impact of jhum cultivation the study was done to analyse the current situation of the practice of shifting cultivation as perceived by the local people of Mokokchung village. We believe that this represents a significant improvement on the shifting cultivation predictions that have been used so far in global land use models to estimate future greenhouse gas emissions, and we hope that our estimates can be a valuable input for future comparisons between models and international synthesis studies such as the upcoming Coupled Model Intercomparison Project Phase 6 (CMIP6) experiments [27] and the next Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). We have nonetheless ventured to display our estimates in predictive maps because they are based on a spatially explicit analysis in 2010. Writing review & editing, Affiliation After eliminating papers that were not related to recent shifting cultivation in the tropics (e.g. One major effect of shifting cultivation is that it destroys valuable plants and animals in the area by going into new environment to clear the bushes and destroyed ecosystem for the sake of farming 3. When the soil begins to turn infertile (usually after 3-5 years) the people move on. We used a search string similar to the one used for the literature review: [Title]: "Shifting cultivation" or swidden or "slash-and-burn" or "slash and burn" or "shifting agriculture" AND [Year published]: 20052015. Click through the PLOS taxonomy to find articles in your field. Improvements in mapping the extent of shifting cultivation and trends in its development may be expected in the near future. The ashes are then mixed with the soil. This figure was elaborated by the first author using ArcGIS 10.4. https://doi.org/10.1371/journal.pone.0184479.g003. Globally, sixty-two per cent of the investigated one-degree cells showed signs of shifting cultivation, with surprisingly similar shares across the 3 regions, ranging between 59 and 65% (Table 1) In absolute terms, the majority of cells with shifting cultivation are located in the Americas and Africa (almost 78%). Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, United States of America, Roles Fig 1A shows a one-degree square of northern Laos. Please refer to the appropriate style manual or other sources if you have any questions. Based on existing data and knowledge, we have made a first attempt at estimating possible future trends in the distribution of shifting cultivation until 2090. [10] compiled available published shifting cultivation area estimates for seven countries: Thailand, Laos, Cambodia, Vietnam, Myanmar, Malaysia, and Indonesia. By zooming into areas where these clearings indicate possible shifting cultivation, we were able to determine visually whether they were accompanied by the pattern of fallows characteristic of shifting cultivation (Fig 1E) or not (Fig 1D). (Fig 2C): One-degree cell with a mesh of 1/100 degree cells as a basic unit for the validation data set, green cells having a shifting cultivation occurrence class of >1% in our global classification. Applying these largely survey-based estimates (Table 3) to our map of the extent of shifting cultivation in 2010 (Fig 5), we were able to visually display our rough predictions of developments in the extents of shifting cultivation by 2030, 2060, and 2090 (Fig 7). and the overall accuracy and the Cohens kappa coefficient were calculated. An online questionnaire was designed and sent to these 270 authors in September 2015 using survey monkey. It does so by following natural cycles, recycling nutrients and water, while omitting excessive use of agricultural chemicals. Formal analysis, Moreover, it is not possible to know in detail how the respondents arrived at their assessment of past and future extents of shifting cultivation. Most plants and animals live in areas with very specific climate conditions, such as temperature and rainfall patterns, that enable them to thrive. We compared this result to Butlers (1980) binary (presence or absence) map of shifting cultivation, gridded into one-degree cells. Of the remaining 225 authors, 72 responded and 49 provided usable information (see S1 File). Trends in humid tropical Africa vary widely. Competing interests: The authors have declared that no competing interests exist. https://doi.org/10.1371/journal.pone.0184479.s001. Panama, Guatemala) well into the 2000s. After analyzing the spatially differentiated changes between the status in the 1960s to 1970s as shown in the Butler map and our data for 2010 (Fig 6), we combined them with data from our expert survey about changes in areas under shifting cultivation between 1970 to 2000 and 2000 to 2010 as well as with information from the literature. With these caveats in mind, we aggregated responses to the national scale and to three supranational regions: the tropical parts of 1) Central and South America, 2) Africa, and 3) Asia. Writing review & editing, Affiliation For this reason, we have estimated future changes in shifting cultivation by combining observed trends between the Butler map and our own map with experts survey responses regarding future changes in shifting cultivation in different parts of the world. Agricultural methane doesn't only come from animals, though. The authors estimated that these areas made up 13.1% of the countrys total land area in 2010; assuming the Democratic Republic of the Congo has a land area of 2.27 million km2 [59], this would amount to nearly 30 Mha, compared to 16 Mha based on the global GLC2000 data set in Silva et al. For large parts of insular Southeast Asia and South Asia (e.g. Livestock may be at risk, both directly from heat stress and indirectly from reduced quality of their food supply. - Papua New Guinea: Shifting cultivation may persist well into the second half of this century, perhaps even until 2090. Corrections? It is a system of rotating cultivation on a plot of land for 2-3 years and leaves it fallow for another 10-15 years. As the data we used (GFC as well as Bing and Google imagery) cover the period from 2000 to 2014 and 2015, respectively, our assessment of the current extent of shifting cultivation does not relate to any specific year. Discover a faster, simpler path to publishing in a high-quality journal. The result shows that 68% of population practice shifting cultivation where out of it 69% of the locals depend on other activities other than agriculture but a high percent of people still. The search was performed in January 2016 and generated 324 articles, which we then screened for data on numbers or estimates of global or national areas influenced by shifting cultivation. The analysis presented is primarily qualitative with a supplementary quantitative analysis of the causes of forest . To approximate the current extent of shifting cultivation landscapes globally we used the results of a time-series analysis of mainly Landsat images characterizing forest extent and change [8], hereafter referred to as Global Forest Change (GFC) data set. But developing predictions is essential to estimating future land usebased greenhouse gas emissions, and we consider that our approach will help to improve existing projections, which essentially assume the area under shifting cultivation to remain constant in the future [2]. In shifting cultivation method of agriculture an area of land is cleared off its vegetation and cultivated for a period of time and then abandoned. Writing original draft, Nobody knows how many people today depend on shifting cultivation globally [22]. For Southeast Asia, Schmidt-Vogt et al. This is called shifting cultivation. The aforementioned map produced by Butler [13] (Fig 4) is a hand-drawn representation of areas where both shifting and non-shifting primitive subsistence agriculture exists, as Butler put it. Population growth, economic development and urban migration have stimulated unprecedented demand for animal protein and with the global population approaching 10 billion, this hunger is expected to increase by up to 70 per cent by 2050 . [3037]) such approaches cannot yet be up-scaled to global level due to data availability as well as computational limitations. Benefits of sustainable agriculture for the environment and our wellbeing. Writing original draft, Roles The downed vegetation, or "slash", is then left to dry, usually right before the rainiest part of the year.Then, the biomass is burned, resulting in a nutrient-rich . Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest or woodland to create a field called a swidden.The method begins by cutting down the trees and woody plants in an area. The map shows large areas under such agriculture in Africa, tropical Central and South America, and Southeast Asia. For large parts of Southeast Asia, the survey results point towards that the current swift decrease in shifting cultivation continues, and that a large share of the area under shifting cultivation will have disappeared by 2030, and the remaining pockets are likely to be almost entirely gone by 2060.Moreover, the survey results indicate trends for some specific Asian countries: Humid tropical Africa is probably the region for which developments are most difficult to predict due to limited data. https://doi.org/10.1371/journal.pone.0184479.t002. These approaches, however, are still in the making and will require substantial resources. Conceptualization, The red box marks the extent of Fig 2D and Fig 2E. Shifting agriculture has frequently been attacked in principle because it degrades the fertility of forestlands of tropical regions. Visualization, No, Is the Subject Area "Asia" applicable to this article? Climate change has caused increased heat, drought, and insect outbreaks. Climate change will also worsen a range of risks to the Great Lakes. The very low occurrence of shifting cultivation within a majority of cells, particularly in the Americas, points towards shifting cultivation being either a form of cultivation practiced in landscapes where only a minor share of the land is used for agriculture (e.g.

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