While the literature offers good representations of the major natural land covers and human land uses [68], mosaic landscapes with a dynamic mix of managed and natural land covers often fall through the cracks in global land cover and land use classifications, as these are unable to adequately capture such landscapes dynamic nature and complex spectral signatures [912]. No, Is the Subject Area "Deforestation" applicable to this article? 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 . 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. [24], who in turn had cited Dixon et al. However, the occurrence of shifting cultivation within most of the individual one-degree cells is very low, meaning that it is a minor component of the overall landscape. In some specific areas, especially in Central Africa, it is likely to increase over the next decade before it begins to decline. Sample: 2A Score: 7 This response earned full credit and demonstrates a comprehensive understanding of subsistence agriculture and the sustainability of shifting cultivation in the past and for the future. This technique serves to clear the field and enrich the soil with nutrients from the ash. d. It accounts for 26% of the gross domestic product. This left us with 2,817 one-degree cells, which we then further investigated. Mozambique), northern mainland Southeast Asia (northern Laos and Myanmar), Borneo, and, to a lesser degree, Central America, Colombia, and Peru. [51] citing Sanchez et al. 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. [2] included shifting cultivation in a global harmonization of land use states and transitions from past to future: they found only one (hand-drawn) global map of shifting cultivation, in a book on economic geography dating from 1980 [13]. On the other hand, large areas with shifting cultivation in Central Africa, for example in the Democratic Republic of the Congo [36], are strongly under-represented in Silva et al. 1,063 likes, 4 comments - Simran IAS Academy (@simranias) on Instagram: "#Learnbymaps is here to explain you about #Slash and #Burn Cultivation Slash and burn #agricultu." Simran IAS Academy on Instagram: "#Learnbymaps is here to explain you about #Slash and #Burn Cultivation Slash and burn #agriculture is also called the shifting cultivation. [52]; the latter source, however, does not provide this information, so the 1,000 Mha claim seems to be unfounded. Validation, More widespread signs of shifting cultivation were found mostly in small pockets, with the exception of larger areas in Central Africa (e.g. We are very grateful to Laura Ebneter, Manuel Abebe, Lukas Wuersch and Boris Fuhrer for their support in interpreting the satellite imagery and to Marlne Tibeault for the language editing. Of the remaining 225 authors, 72 responded and 49 provided usable information (see S1 File). Unlike intensive agriculture, sustainable farming has a great potential for benefiting the environment and preserving natural resources. [10] compiled available published shifting cultivation area estimates for seven countries: Thailand, Laos, Cambodia, Vietnam, Myanmar, Malaysia, and Indonesia. As for Africa, we found only one recent national study, on the Democratic Republic of the Congo [36]. South America shows mixed trends: Areas under shifting cultivation have clearly decreased in the southern Brazilian Amazon, whereas survey responses indicate that they are expanding in other parts of the Brazilian Amazon and in Peru. 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. Fig 1 illustrates the procedure we used for this visual inspection. Human influence on the land is accelerating because of rapid population growth and increasing food requirements. The length of time that a field is cultivated is usually shorter than the period over which the land is allowed to regenerate by lying fallow. For more information about PLOS Subject Areas, click No source is reported for the map, but most likely it builds on a number of regional studies that was carried out between the 1940s and the 1970s, as well as general knowledge of where shifting cultivation and other extensive smallholder farming systems were found. Updates? With 62% of the investigated one-degree cells in the humid and sub-humid tropics currently showing signs of shifting cultivationthe majority in the Americas (41%) and Africa (37%)this form of cultivation remains widespread, and it would be wrong to speak of its general global demise in the last decades. Peninsular Malaysia, central and southern Thailand) [28]. 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). Such areas are found in parts of Southeast Asia (e.g. IWGIA - IWGIA - International Work Group for Indigenous Affairs In addition, we used available very highresolution satellite imagery from Bing and Google (most images dating from the period between 2008 and 2015; visited between September and April 2015) in an ArcGIS Desktop 10.4 and QGIS environment to examine visually whether a given area for which the GFC data indicated a spatio-temporal pattern of small-scale clearings consistent with shifting cultivation, was indeed likely to be under shifting cultivation. See also slash-and-burn agriculture. While shifting cultivations signature on the landscape may be captured as a mixture or mosaic of agriculture and forest land cover classes, this alone does not suffice to indicate with certainty the presence of shifting cultivation. However, more severe warming, floods, and drought may reduce yields. The data sources are not entirely clear, but the assessment seems to be based on a number of studies carried out between the end of the 19th century and the late 1950s, along with expert judgement. The impacts of traditional agriculture on Environment are discussed below: 1. Shifting cultivation systems are ecologically viable as long as there is enough land for long (10-20 years) restorative fallow, and expectations of crop yield and the attendant standards of living are not too high. Extreme heat, heavy downpours, and flooding will affect infrastructure, health, agriculture, forestry, transportation, air and water quality, and more. Writing original draft, 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). Environment; Why poison ivy is an unlikely climate change winner. The research presented here contributes to the objectives of the Global Land Programme (glp.earth). Shifting Cultivation Shifting Cultivation Agricultural Geography Agricultural Hearths Agricultural Production Regions Agricultural Revolutions Agriculture and Climate Agriculture and Pollution Agrochemicals Community Supported Agriculture Extensive Farming Feeding the World Food Desert Food Insecurity Food Movements Green Revolution Moreover, even if GFC deforestation data processing using the Google Earth engine might enable this automation in the future, the visual approach will still be highly valuable for validating the robustness of automated approaches. Regarding South and Southeast Asia, a meta-analysis by van Vliet et al. 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]. It does so by following natural cycles, recycling nutrients and water, while omitting excessive use of agricultural chemicals. Climate change will also worsen a range of risks to the Great Lakes. The accuracy levels of our classification were high with an overall accuracy above 87%. [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]. No, PLOS is a nonprofit 501(c)(3) corporation, #C2354500, based in San Francisco, California, US, Corrections, Expressions of Concern, and Retractions, https://doi.org/10.1371/journal.pone.0184479, ftp://ftp.fao.org/docrep/fao/003/y1860e/y1860e00.pdf, https://www.cia.gov/library/publications/the-world-factbook/geos/cg.html. 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). 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. The principle of cultivation is to turn the soil into a fine tilth to provide the ideal environment for seeds to germinate. It is a form of farming practice that entails clearing a land parcel by felling and burning trees. First, an area of fallow forest is cleared for cultivation. Recent international efforts to compare and synthesize different earth system models have come with a strong focus on quantifying the past, current, and future contributions of land use to climate change [14]. The excessive growth (or bloom) of algae and plankton in a water body are indicators of this process. of Energy, grant number DE-SC0012972, and the Global Land Project Grant from the University of Copenhagen. Second, we combined the results of this comparison with those of our expert survey. Cultivation of the earth after clearing is usually accomplished by hoe or digging stick and not by plow. Lastly, it is also problematic that shifting cultivation has been subject to recycling of statements about its importance that have no basis in thorough empirical research. Predicting future trends in the development of any form of land use requires extreme caution [23,69]. 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. Writing original draft, [24]). No, Is the Subject Area "Earth systems" applicable to this article? Yes These changes are not fully reflected in the above comparison between the Butler map and our own spatial investigation for 2010 because in many areas they have resulted only in a reduced occurrence of shifting cultivation but not yet in its full disappearance. Due to its low productivity and incompatibility with most cash crops, shifting cultivation may lock farmers into 'land use' poverty traps. But information about such landscapes is urgently needed to improve the outcomes of global earth system modelling and large-scale carbon and greenhouse gas accounting. We did not perform any detailed spatial delineation of the actual area under shifting cultivation, as the goal of our study was to provide a global one degreegridded product. [43] when using the same source material for the classification as for the reference or validation data, it is essential to create the reference/validation data with a more accurate process than the classification. Forest and trees play an important role in balancing the environment. This study combines existing global Landsat-based deforestation data covering the years 2000 to 2014 with very high-resolution satellite imagery to visually detect the specific spatio-temporal pattern of shifting cultivation at a one-degree cell resolution worldwide. Methodology, Road Building The Transamazon Highway has allowed increased access to the Amazon Rainforest. - Indicate shifting cultivation area changes in the following periods of the past (no change, expansion, decline, disappearance): 19001970; 19702000; 20002015. This is reflected both in the comparison of the two spatial data sets (Fig 6) and in the survey responses. Although the areas shown on the map also include non-shifting forms of subsistence agriculture, it is reasonable to assume that shifting cultivation predominated in the humid and sub-humid tropics, which are the main focus of the present study. [1] used the Global Land Cover 2000 (GLC2000) data set [53] and the Map of the Ecosystems for Central America [54] to estimate the extent of shifting cultivation at the global scale. Analysis of Landsat data back to Landsat4 (launched in 1982) could provide more than 30 years of pan-tropical records, covering a time of significant change in the distribution of shifting cultivation across the humid tropics and perhaps also in the length of fallow periods. This figure was elaborated by the first author using ArcGIS 10.4. https://doi.org/10.1371/journal.pone.0184479.g007. The red box marks the extent of Fig 2D and Fig 2E. and the overall accuracy and the Cohens kappa coefficient were calculated. Writing original draft, Given the unavailability of automated approaches to detect shifting cultivation at a global level and deliver data in a timely manner for ongoing earth system modeling, we have used a visual interpretation approach to detect shifting cultivation. Fig 1A shows a one-degree square of northern Laos. Solution Shifting Cultivation: Slash-and-burn cultivation is another name for shifting cultivation. [17] showed that these regions have experienced marked decreases in shifting cultivation. This approach, however, suffers from the shortcoming that land cover data are of very limited use in estimating land use practices, which is acknowledged by Silva et al. There is a need to transform shifting cultivation to sustainable intensification. The area approximation of actual shifting cultivation landscapes was performed based on the average occurrence rates in the one-degree cells for each of the five classes above (>1% class: 0%; 19%: 5%; 1019%: 15%; 2039%: 30%; 40%:70%). Nevertheless, shifting agriculture is an adaptation to tropical soil conditions in regions where long-term, continued cultivation of the same field, without advanced techniques of soil conservation and the use of fertilizers, would be extremely detrimental to the fertility of the land. Eutrophication is considered to be a serious environmental concern since it often results in the . The areas referred to as the rural complex may be used as a proxy for the presence of shifting cultivation. To generate a spatially explicit prediction of the temporal dynamics (decline) of shifting cultivation through to the 2090s, we combined the survey results with several simple assumptions. [3037]) such approaches cannot yet be up-scaled to global level due to data availability as well as computational limitations. Yes Laos, Vietnam) over the past 15 to 25 years is not reflected in this comparison. Concludes by addressing the need to protect and conserve the natural forests and wild life. 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). Regarding Central and South America, the only available source [57] used the secondary forest class as defined in FAOs Forest Resource Assessment 1990 [58] as a proxy and stated the area under shifting cultivation to be 165 Mha. Writing review & editing, Affiliation We initiated occurrence at a one-degree resolution in 2010 (base year) at the mean of the above-stated ranges for each occurrence category in the assessment of current landscape with signs of shifting cultivation based on the GFC data (c.f. There's no doubt about it: the best thing we can do to fight climate change is keep forests standing. No, Is the Subject Area "Asia" applicable to this article? in parts of Southeast Asia). 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 producers and users accuracies were calculated for each occurrence class (< 1%; very low: 19%; low: 1019%; moderate: 2039%; high: 40%.) The Neolithic Revolutionalso referred to as the Agricultural Revolutionis thought to have begun about 12,000 years ago. 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. decadal), the areas newly classified as having shifting cultivation (blue in Fig 6) should be added to the original Butler map, thereby producing an updated estimated extent of shifting cultivation for this earlier period. First, we compared the Butler [13] map (Fig 4) with our own spatial estimate (Fig 5) of areas that were under shifting cultivation around 2010. No, Is the Subject Area "Agriculture" applicable to this article? No, Is the Subject Area "Africa" applicable to this article? Visualization, In soil-based agriculture, soil health is the most important foundation of a healthy farm ecosystem. As for the entire global level assessment of all the 2,817 one degree cells considered, the GEFC and available very high resolution imagery (i.e. 2030, 2060, 2090) shifting cultivation was expected to disappear completely from a specific country (n = 21), all one-degree cells having their centroid within that country where classified as having zero occurrence of shifting cultivation after that time, regardless of the above-described gradual decrease. Maps created in QGIS 2.16. https://doi.org/10.1371/journal.pone.0184479.g001. However, this future may also provide better opportunities for production and income generation if development efforts are sensitive to the needs of shifting cultivators [73,74]. Centre for Development and Environment, University of Bern, Bern, Switzerland, Roles - Papua New Guinea: Shifting cultivation may persist well into the second half of this century, perhaps even until 2090. When looking at this comparison, it is important to keep in mind that only full disappearance of shifting cultivation within a one-degree cell will show as a change between the two data sets; gradual decreaseswhich normally precede full disappearanceare not captured if the occurrence of shifting cultivation in the respective cells according to our present estimate remains greater than 5%. Australia, the Gulf States, arid areas in Africa) or where it disappeared several decades ago (e.g. India, Bangladesh), comparison of the maps (Fig 6) and the survey responses point to similar trends. northern Zambia and in the Democratic Republic of the Congo), parts of southeastern Africa (e.g. Deforestation is also a contributor to climate change and global warming. Shifting cultivation is the major occupation and the main source of income of the marginal farmers ( Jhumias) in Mizoram. If the survey provided information about when (i.e. To date, we know little about its worldwide extent, underlying spatial patterns, or global trends in its past and future development. Many of the other decreases from Butlers to our map (dark brown in Fig 6) can also most likely be related to the actual disappearance of shifting cultivation in these areas that have seen significant land use transitions over the past 40 to 50 years. Articles with data at subnational scales were only considered if the subnational area studied constituted the main area of shifting cultivation in the given country (and thus a reasonable estimate of the national extent of shifting cultivation). Methodology, The Data behind Deforestation Causes of Deforestation We compared this result to Butlers (1980) binary (presence or absence) map of shifting cultivation, gridded into one-degree cells. - The primary disadvantage of shifting cultivation is cutting down of forest, which further leads to deforestation. This paper presents the causes and consequences of shifting cultivation and its potential land use alternatives. Fig 1B to Fig 1E show examples of different zoom levels used to decide whether the pattern in the GFC data is indeed related to shifting cultivation Fig 1E (showing pattern of clearing for the current year of cultivation and different stages of fallow) or not Fig 1D (larger scale clearings with young rubber). 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 a second cluster of countriesLaos, Cambodia and Myanmarshifting cultivation areas have decreased drastically since 2000.