In Central America, shifting cultivation is still widespread, and both Fig 6 and the survey results indicate an increase in some areas (e.g. 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. It is a sustainable method of farming in the rainforest. [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]. 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. No, Is the Subject Area "Asia" applicable to this article? - Indicate shifting cultivation area changes in the following periods of the past (no change, expansion, decline, disappearance): 19001970; 19702000; 20002015. Writing review & editing. 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. Hence, the occurrence level was estimated and not measured and the classification was based on a coarse assessment of the landscape (also see accuracy assessment below). 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. Visualization, After eliminating papers that were not related to recent shifting cultivation in the tropics (e.g. The analysis presented is primarily qualitative with a supplementary quantitative analysis of the causes of forest . Yes As growing only one kind of plant on the same piece of farmland depletes and exhausts the soil by depriving it of the biodiversity, farmers tend to artificially boost the fertility of their impacted fields by applying chemical fertilizers. Copyright: 2017 Heinimann et al. A plot of land is cleared by cutting the trees and burning them. The global shift towards this model of farming in the last sixty years has come with many costs. Spencers hand-drawn map is largely in agreement with Butlers for most areas, but it shows larger areas under shifting cultivation in Thailand, Myanmar, India, and Sri Lanka. [24]). There's no doubt about it: the best thing we can do to fight climate change is keep forests standing. Writing original draft, 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. Madagascar has seen only slight decreases; especially along its eastern escarpment the area under shifting cultivation has remained stable over the last two decades (e.g. To date, we know little about its worldwide extent, underlying spatial patterns, or global trends in its past and future development. The evil effects of shifting cultivation are devastating and far reaching in degrading the environment and ecology of this region. [51] citing Sanchez et al. (2017) A global view of shifting cultivation: Recent, current, and future extent. Cultivation (tillage) is a practice that has been introduced to Australia from Europe by our farming pioneers. This is reflected both in the comparison of the two spatial data sets (Fig 6) and in the survey responses. In order to assess both past and future land use transitions in areas currently under shifting cultivation, we identified experts with recent knowledge of these areas by searching the Web of Science (All Databases) for papers published between 2005 and 2015 whose title contained shifting cultivation or similar terms. No, Is the Subject Area "Africa" applicable to this article? Improvements in mapping the extent of shifting cultivation and trends in its development may be expected in the near future. Visualization, 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. Writing original draft, These systems are naturally suited for harsh environments and fragile ecosystems of the tropics. b. The remaining cells (3,887) were excluded from the analysis as shifting cultivation can be assumed to have never existed or disappeared decades ago (see Fig 5 and Method section). [10] compiled available published shifting cultivation area estimates for seven countries: Thailand, Laos, Cambodia, Vietnam, Myanmar, Malaysia, and Indonesia. 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). Extreme weather. In our classification the occurrence for shifting cultivation was estimated at a low level, meaning 1019%, which in this case was in line with the validation data set. The ranges are based on the expert survey and observed trends between the Butler map and our 2010 classification (Fig 5). While our estimates are based on non-automated methods and expert information from different parts of the world, we argue that our work nonetheless advances the state of knowledge considerably, especially with regard to earth system modeling scenarios, which have proved sensitive to the inclusion of shifting cultivation and up to now have used shifting cultivation data based on a hand drawn map from the 1980s. Our main objectives in this study are therefore 1) to review published knowledge about current status and past trends in the development of the global extent of shifting cultivation; 2) to assess the recent global distribution of shifting cultivation and, based on these trends and expert statements, 3) to provide a first estimation of the future extent and spatial distribution of shifting cultivation until 2090. Shifting cultivation decreases the activities of useful microorganisms found in the soil. No, Is the Subject Area "Earth systems" applicable to this article? India, Bangladesh), comparison of the maps (Fig 6) and the survey responses point to similar trends. This causes degradation of land, soil erosion, etc. 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. Click through the PLOS taxonomy to find articles in your field. 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%). 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 earlier 15-20 years cycle of shifting cultivation on a particular land has reduced to two or three years now. It is a serious environmental concern since it can result in the loss of biodiversity, damage to natural habitats, disturbances in the water cycle, and soil erosion. Methodology, For Southeast Asia, Schmidt-Vogt et al. Outlines the natural features of Mizoram climate, flora, fauna. On the basis of archaeological evidences and radio-carbon dating, the origin of shifting cultivation could be traced back to about 8000 BC in the Neolithic period which witnessed the remarkable and revolutionary change in man's mode of production of food as from hunter and gatherer he became food producer. It is a form of farming practice that entails clearing a land parcel by felling and burning trees. From droughts and wildfires to pests and pathogens, climate change is wreaking havoc on the world's forests. and the overall accuracy and the Cohens kappa coefficient were calculated. It coincided with the end of the last ice age and the beginning of the. If the survey provided information about when (i.e. Why poison ivy is an unlikely climate change winner. One land-clearing system of shifting agriculture is the slash-and-burn method, which leaves only stumps and large trees in the field after the standing vegetation has been cut down and burned, its ashes enriching the soil. Discover a faster, simpler path to publishing in a high-quality journal. The spatio-temporal pattern of the annual deforestation data from 2000 to 2014 at a resolution of 30 meters provides the basis for our approximation. Visual interpretation has well-known limitations in terms of subjectivity and potentially limited reproducibility [29], but there are two main reasons why a visual approach has been chosen: Firstly, while a number of approaches has recently been developed to detect shifting cultivation based on automated approaches at the regional and national level using remote sensing data (e.g. northern Zambia and in the Democratic Republic of the Congo), parts of southeastern Africa (e.g. To get a first estimation of the occurrence of shifting cultivation, we classified each cell under investigation into one of five shifting-cultivation occurrence classes: none, very low, low, moderate, or high. Habitable land is land that is ice- and desert-free. However, more severe warming, floods, and drought may reduce yields. Also when considering the different levels of occurrence of shifting cultivation estimated based on the overall impression of the landscape per one-degree cell, the accuracies were high (see confusion matrix in Table 2), with an overall classification accuracy of 87.8%. Eutrophication is the process in which a water body becomes overly enriched with nutrients, leading to plentiful growth of simple plant life. Solution Shifting Cultivation: Slash-and-burn cultivation is another name for shifting cultivation. 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. However, we found that its occurrence in most one-degree cells, where it existed, was fairly limited, with roughly 85% of these cells showing occurrence levels below 20% (currently cultivated fields and all stages of fallows). Please refer to the appropriate style manual or other sources if you have any questions. However, it is important to underline that this assessment is based on very few survey responses (Fig 3) due to the small number of existing studies on shifting cultivation in Africa. Data curation, Roles Areas drenched by irrigation can become waterlogged, creating soil conditions that poison plant roots through anaerobic decomposition. Taking into consideration the stratification criteria, 328 one-degree cells were randomly selected to be validated. 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. Yes [68]). Writing review & editing, Affiliations 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. Road Building The Transamazon Highway has allowed increased access to the Amazon Rainforest. 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). The accuracy levels of our classification were high with an overall accuracy above 87%. Data Availability: All relevant data are within the paper and its Supporting Information files. Omissions? Depletion of Nutrients The primitive style of framing like slash and burn decreases the organic matter from the soil. The difference appears plausible if we consider that Spencers estimate is based on a hand-drawn map and that Asia has seen considerable decreases in shifting cultivation since that map was created (see section on recent trends below). 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). 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]. d. It accounts for 26% of the gross domestic product. Climate change is a leading cause of deforestation. Logging Writing original draft, 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. Conceptualization, The search was performed in September 2015 and generated 316 results. There is a need to transform shifting cultivation to sustainable intensification. The comparably low user and producer accuracies of the class moderate occurrence (2039% coverage of shifting cultivation landscapes of the entire one-degree cell) is not surprising as it could have been expected that this intermediate class would be the most difficult one to estimate. Based on visual inspection of annual global deforestation data [8] from 2000 to 2014 and very high-resolution satellite imagery. Environment; What you can do right now to advocate for the planet. current practice of shifting cultivation in the region is an extravagant and unscientific form of land use. Shining cultivation fields are generally used not more than two years at a lime, after which . Other Causes of Deforestation Forest Fires Fires are a natural part of the lifecycle of many forests, clearing the way for younger, smaller growth. Writing review & editing, Affiliation https://www.britannica.com/topic/shifting-agriculture. For India, Goswami et al. archeological studies or historical studies of shifting cultivation in Europe), duplicates, and papers whose authors had deceased in the meantime, 282 papers remained. A review focusing on Southeast Asia found little aggregate information about the areas under shifting cultivation there [10], and we were unable to find information about shifting cultivation areas in Africa and Latin America. Shifting cultivation remains widespread, despite decreases in its extent over the last four to five decades. (Fig 2A): the global distribution of the stratified sample of the 328 one-degree cells used in the validation data set. Mexico and Brazil) likely to see a fairly rapid decrease and disappearance. This indicates that, despite the subjectivity involved on estimating the landscape level of occurrence of shifting cultivation in our classification, the method led to reproducible and accurate results. - Indicate how you expect the shifting cultivation occurrences to change in the future for the following periods (no change, expansion, decline, disappearance): 20152030; 20302060; 20602090. Furthermore, it should be noted that the large difference between the two spatial data sets (Fig 6) in arid and semiarid parts of Africa (Sahelian and Sudanian zones of northern Africa as well as parts of southern Africa) is partly due to the fact that Butler included other, non-shifting smallholder farming systems in his map. In large parts of humid West Africa, shifting cultivation is still widespreadwith the exception of Nigeria, where it has all but disappeared and remains present only in small pockets. This figure was elaborated by the first author using ArcGIS 10.4. https://doi.org/10.1371/journal.pone.0184479.g007. It received 1 point in At the same time, shifting cultivation was one of the most sensitive variables in their model runs (along with wood harvesting). In eastern and southern Africa, shifting cultivation is still present, but not very common, with particularly low occurrences in Kenya and Tanzania. Validation, We attribute it to 2010 for the sake of simplicity. https://doi.org/10.1371/journal.pone.0184479.t002. 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. An area of 1,000 Mha was mentioned by Davidson et al. Both conditions apply to considerable parts of Central Africa. Climate change will bring more frequent and severe extreme weather events, including extreme precipitation, wind disturbance, heat waves, and drought. [24], who in turn had cited Dixon et al. 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. Data curation, 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. The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more commonly, when the field is overrun by weeds. https://doi.org/10.1371/journal.pone.0184479.t003. 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]. 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%. Centre for Development and Environment, University of Bern, Bern, Switzerland, Roles Intensive agriculture has dominated the global food production . No, Is the Subject Area "Deforestation" applicable to this article? - India and Bangladesh: Shifting cultivation is estimated to disappear by 2030. 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. Let us know if you have suggestions to improve this article (requires login). But information about such landscapes is urgently needed to improve the . Initially, we considered all 6,704 one-degree cells covering the land area between 30S and 30N, where shifting cultivation is likely to occur [17]. The effects of shifting cultivation are devastating and far-reaching in degrading the environment and ecology of these regions. Shifting agriculture has frequently been attacked in principle because it degrades the fertility of forestlands of tropical regions. Consequently, if further research (e.g. Formal analysis, 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. Formal analysis, The history of shifting cultivation is as old as the history of agriculture itself. The Data behind Deforestation Causes of Deforestation [1], possibly owing to the scale (1-km resolution) of the GLC2000 data sets. At the regional scale, an assessment by Spencer [45] provides a slightly more differentiated picture of the presence of shifting cultivation practices in Asia. Nobody knows how many people today depend on shifting cultivation globally [22]. This raises issues of livelihood security and resilience among people currently depend on shifting cultivation, who may face reduced provision of ecosystem services and limited access to land due to the expansion of permanent agriculture, tree plantations, urban areas, and forest protection or restoration [18,19,44,72]. Australia, the Gulf States, arid areas in Africa) or where it disappeared several decades ago (e.g. Validation, This trend, which was also identified by van Vliet et al. As global level ground data collection is not feasible and no global data on shifting cultivation for the considered time span of 2000 to 2014 is available, we generated a validation dataset, which contains a detailed delineation of the areas under shifting cultivation for a stratified sample of one-degree cells. 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. Cultivation was also a traditional form of weed control. See also slash-and-burn agriculture. Methodology, c. Agriculture is the main stay of India's economy. This became particularly evident when Hurtt et al. The results indicate that shifting cultivation is likely to persist longest in Africa. These approaches, however, are still in the making and will require substantial resources. Corrections? In addition to searching the Web of Science, we also consulted three major book publications that could be assumed to contain relevant information [2426]. 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. in parts of Southeast Asia). More widespread signs of shifting cultivation were found mostly in small pockets, with the exception of larger areas in Central Africa (e.g. As for Africa, we found only one recent national study, on the Democratic Republic of the Congo [36]. - Shifting cultivation also destroys the habitat of wild animals at large. While keeping in mind the inherent limitations of these predictions, we can identify a number of more specific patterns. Disadvantages of Shifting cultivation: Deforestation Loss of fertility of a specific site Soil erosion Tree burning generates air pollution. The global food system is in crisis. The number of estimates of areas under shifting cultivation at regional and national scales in the literature is also very limited. Formal analysis, This left us with 2,817 one-degree cells, which we then further investigated. 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. The 270 first authors of these papers were listed and their email addresses were found. Soil is the foundation of most types of agriculture. 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 . Our cautious estimation indicates that the global extent of shifting cultivation, including currently cultivated fields and all stages of fallows, may amount to roughly 280 Mha, with the largest share in Africa, followed by the Americas and Asia. The plot is left alone for longer than it was cultivated, sometimes up to 10 or more years, to allow wild vegetation to grow on the plot of land. However, adequate prediction of land usebased emissions requires an improved understanding of megatrends in land use systems change [2,5]. Investigation, Forest and trees play an important role in balancing the environment. But soil health is negatively impacted by industrial agriculture practices like monocropping, synthetic fertilizers, pesticides and more. To assess the accuracy of our estimated occurrence levels of shifting cultivation on the landscape, this validation data was used to calculate the actual area shares of the 1/100 by 1/100 one-degree cells classified as having shifting cultivation in validation data for all 328 one degree samples cells. The author has visited the entire Mizoram state and observed that shifting cultivation has a severe adverse impact on the environment, forest depletion and landscape degradation. For example, many of the commercial or smallholder oil palm and rubber plantations that cover large areas of Southeast Asia today are on land that was formerly used for shifting cultivation [1821]. 2], while long cycles comprise fallow periods of more than 15 years (Villa et al., 2020; Villa et al., 2017 . In addition, to the extent multi-temporal very high resolution imagery was available on Google Earth, these were used to get an even better impression of the landscape and its land-use dynamics. As our aim was to provide, in a timely manner, a global-scale overview of landscapes showing signs of shifting cultivation for use in global land userelated earth system modeling scenarios [27], we worked at an aggregated level using one-degree cells, which corresponds approximately to the scale of current earth system model analyses. Writing original draft, Roles This article first questions the share of responsibility assigned to traditional agriculture it may well be overestimated because of unclear definitions, uncertain estimates, and potential political biases. The respondents were asked to estimate the current spatial extent of shifting cultivation as well as past and future trends in the development of this extent in their area of interest. An online questionnaire was designed and sent to these 270 authors in September 2015 using survey monkey. Based on this we expect that shifting cultivation is likely to decrease significantly in all regions over the next 20 years, and we estimate that it will tend towards disappearance in all regions by 2090 (Table 3). Competing interests: The authors have declared that no competing interests exist. 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. [3037]) would be insufficient, as they only cover very few of our one-degree cells and are not representative globally. This technique serves to clear the field and enrich the soil with nutrients from the ash. 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. Conceptualization, Surprisingly, our estimate is not too far from the 259 Mha proposed in Silva et al [1], even though their estimate excludes large areas under shifting cultivation and includes areas under other forms of agriculture and natural vegetation. We estimate that shifting cultivation landscapes currently cover roughly 280 million hectares worldwide, including both cultivated fields and fallows. The areas referred to as the rural complex may be used as a proxy for the presence of shifting cultivation. 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.