In a book called Shifting cultivation policies: Balancing environmental and social sustainability (2017), an outline of the role of government and local institutions in regulating shifting . No, Is the Subject Area "Surveys" applicable to this article? The red box marks the extent of Fig 2D and Fig 2E. 5. Formal analysis, It does so by following natural cycles, recycling nutrients and water, while omitting excessive use of agricultural chemicals. Formal analysis, Using recent regional and national automated classification of shifting cultivation as reference (e.g. Writing original draft, Most plants and animals live in areas with very specific climate conditions, such as temperature and rainfall patterns, that enable them to thrive. 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. 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. 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. 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]. 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. Plants, Animals, and Ecosystems. The number of estimates of areas under shifting cultivation at regional and national scales in the literature is also very limited. More widespread signs of shifting cultivation were found mostly in small pockets, with the exception of larger areas in Central Africa (e.g. - The primary disadvantage of shifting cultivation is cutting down of forest, which further leads to deforestation. An online questionnaire was designed and sent to these 270 authors in September 2015 using survey monkey. Formal analysis, There is a need to transform shifting cultivation to sustainable intensification. For this reason, the known widespread decrease in the occurrence of shifting cultivation in Southeast Asia (e.g. No, Is the Subject Area "Agriculture" applicable to this article? No, Is the Subject Area "Deforestation" applicable to this article? Data curation, It is a sustainable method of farming in the rainforest. As for Africa, we found only one recent national study, on the Democratic Republic of the Congo [36]. To stress the interactions between society and the environment, the driving forces (D), pressures (P), states (S), impacts (I), and response (R) (DPSIR) framework approach . Writing original draft, of Energy, grant number DE-SC0012972, and the Global Land Project Grant from the University of Copenhagen. 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. 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. The earlier 15-20 years cycle of shifting cultivation on a particular land has reduced to 2-3 years now. 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. The stratified validation sample design was chosen considering the distribution of the validation samples per occurrence class and the spatial distribution per continents. https://www.britannica.com/topic/shifting-agriculture. 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. Writing original draft, 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. 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 ranges are based on the expert survey and observed trends between the Butler map and our 2010 classification (Fig 5). 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. 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. Yes 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. This is reflected both in the comparison of the two spatial data sets (Fig 6) and in the survey responses. - Vietnam and Laos: Shifting cultivation is likely to be greatly reduced by 2030 and completely gone by 2060. After eliminating papers that were not related to recent shifting cultivation in the tropics (e.g. d. It accounts for 26% of the gross domestic product. - 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. Conceptualization, (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. Eutrophication is considered to be a serious environmental concern since it often results in the . 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. This became particularly evident when Hurtt et al. For India, Goswami et al. No, Is the Subject Area "Asia" applicable to this article? 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 . Moreover, it is not possible to know in detail how the respondents arrived at their assessment of past and future extents of shifting cultivation. 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. 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. Our review of the more recent literature revealed surprisingly few studies containing regional or global estimates of areas under shifting cultivation. The earlier 15-20 years cycle of shifting cultivation on a particular land has reduced to two or three years now. [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. The effects of shifting cultivation are devastating and far-reaching in degrading the environment and ecology of these regions. - Central Africa: Shifting cultivation is estimated to persist well into the 2060s or longer due to the vast reserve of remote forested areas. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Degradation is the gradual decline of forested areas that does not result in complete deforestation. Extreme heat, heavy downpours, and flooding will affect infrastructure, health, agriculture, forestry, transportation, air and water quality, and more. Mosaic landscapes under shifting cultivation, with their dynamic mix of managed and natural land covers, often fall through the cracks in remote sensing-based land cover and land use classifications, as these are unable to adequately capture such landscapes' dynamic nature and complex spectral and spatial signatures. [24]). While keeping in mind the inherent limitations of these predictions, we can identify a number of more specific patterns. Mexico and Brazil) likely to see a fairly rapid decrease and disappearance. Roles Yes 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. Shifting cultivation has often been blamed as the main cause of deforestation and forest degradation [911,14,15], but evidence is growing that when shifting cultivation is discontinued, it is often replaced by intensified land uses with higher environmental impacts [16,17]. https://doi.org/10.1371/journal.pone.0184479.t002. The map shows large areas under such agriculture in Africa, tropical Central and South America, and Southeast Asia. Venezuela [67]), and Madagascar [68]. 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 . [10] compiled available published shifting cultivation area estimates for seven countries: Thailand, Laos, Cambodia, Vietnam, Myanmar, Malaysia, and Indonesia. The impacts of traditional agriculture on Environment are discussed below: 1. Our preliminary estimated for the future indicate that the area under shifting cultivation is expected to shrink considerably over the next decades. 5 Ways Climate Change Impacts Forests. Climate change will also worsen a range of risks to the Great Lakes. Both conditions apply to considerable parts of Central Africa. 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 history of shifting cultivation is as old as the history of agriculture itself. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. Bing and Google Earth) were used. To date, we know little about its worldwide extent, underlying spatial patterns, or global trends in its past and future development. Maps created in QGIS 2.16. https://doi.org/10.1371/journal.pone.0184479.g001. Formal analysis, (2017) A global view of shifting cultivation: Recent, current, and future extent. Is the Subject Area "Land use" applicable to this article? One of the most obvious consequences is the depletion of aquifers, river systems, and downstream ground water. The area calculation was done within a Mollweide projection. Such areas are found in parts of Southeast Asia (e.g. Copyright: 2017 Heinimann et al. Mozambique), northern mainland Southeast Asia (northern Laos and Myanmar), Borneo, and, to a lesser degree, Central America, Colombia, and Peru. Yes 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. Validation, 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). Road Building The Transamazon Highway has allowed increased access to the Amazon Rainforest. 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. 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. Disadvantages of Shifting cultivation: Deforestation Loss of fertility of a specific site Soil erosion Tree burning generates air pollution. About half of tropical deforestation is commonly explained by the expansion of traditional agriculture (shifting cultivation). Nearly two-thirds of its population depends directly on agriculture for its livelihood. 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. Climate change will bring more frequent and severe extreme weather events, including extreme precipitation, wind disturbance, heat waves, and drought. 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. The present study is a first step towards a future in which we will know more about the global distribution of shifting cultivation; we hope it opens the door to quantifying shifting cultivations importance for local as well as the global socio-ecological systems. This has led to a paucity of global information on certain land use systems, including shifting cultivation at the global level. - 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. 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). Despite the limited number of survey responses on Central and South America, it appears that here, unlike in Southeast Asia, areas under shifting cultivation have not seen a strong decline over the last 20 years. Conceptualization, 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. Investigation, The excessive growth (or bloom) of algae and plankton in a water body are indicators of this process. Extreme precipitation events can disturb plant growth, particularly in recently burned forests, and make plants more vulnerable to flooding and soils to erosion. For Southeast Asia, Schmidt-Vogt 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. - Borneo and Sulawesi: Shifting cultivation is expected to disappear sometime between 2030 and 2060. The global shift towards this model of farming in the last sixty years has come with many costs. 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. Yes Writing review & editing, Affiliation Logging Farmers will have to shift what they grow and how they grow it to keep up with an expanding population. Letting it dry and burning it off. Methodology, Writing review & editing, Roles In the absence of further data to validate past estimations of the extent of shifting cultivation, the Butler map may be considered a reasonable representation of the global distribution of shifting cultivation from 1960 into the 1970s. Fig 1 illustrates the procedure we used for this visual inspection. b. Click through the PLOS taxonomy to find articles in your field. Writing review & editing, Affiliation Improvements in mapping the extent of shifting cultivation and trends in its development may be expected in the near future. After the soil loses its fertility, the land is abandoned and the cultivator moves to a new plot. 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. 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. 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. Extreme weather. Writing original draft, Each of these samples was visually examined in detail at scale of 1:20,000 or lower for the presence or absence of the above mentioned shifting cultivation specific spatio-temporal signs of clearing and regrowth on the landscape. This is called shifting cultivation. The difference between the Butler mapwhich is presumably based on studies dating from the 1960s and 1970s [13]and our own current investigation around 2010 is displayed in Fig 6. Eutrophication is the process in which a water body becomes overly enriched with nutrients, leading to plentiful growth of simple plant life. However, more severe warming, floods, and drought may reduce yields. [52]; the latter source, however, does not provide this information, so the 1,000 Mha claim seems to be unfounded. Outlines the natural features of Mizoram climate, flora, fauna. The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more commonly, when the field is overrun by weeds. broad scope, and wide readership a perfect fit for your research every time. (Source of imagery in 2D and 2E: Pansharpened Landsat 8 image, acquisition date January 5 2014, available from the U.S. Geological Survey.). 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 . Deforestation is also a contributor to climate change and global warming. Thus that abandoned land then gets ample . Data Availability: All relevant data are within the paper and its Supporting Information files. 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. 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). https://doi.org/10.1371/journal.pone.0184479.s001. northern Zambia and in the Democratic Republic of the Congo), parts of southeastern Africa (e.g. Methodology, 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]. 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. The Data behind Deforestation Causes of Deforestation Soil is the foundation of most types of agriculture. Writing original draft, Roles It received 1 point in This figure was elaborated by the first author using ArcGIS 10.4. https://doi.org/10.1371/journal.pone.0184479.g007. Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, United States of America, Roles 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 The most important questions included: The information provided by the respondents related to very different spatial scales, ranging from village to district, provincial, and, in some cases, national scales. (Fig 2A): the global distribution of the stratified sample of the 328 one-degree cells used in the validation data set. Half of the world's habitable land is used for agriculture. The results indicate that shifting cultivation is likely to persist longest in Africa. In Central Africa, shifting cultivation also remains very widespread, with an even higher occurrence than in West Africa; in certain areas it is still expanding, such as in the Democratic Republic of the Congo [36]. According to our tentative predictions, shifting cultivationwhich has been a globally important form of human crop cultivation for millenniamay be gone by the end of this century. A study conducted by the Food and Agriculture Organization (FAO) of the United Nations in 1985 (based on 90 tropical countries reporting forest fallow areas within the FAO/UNEP Tropical Forest Resources Assessment Project 1982 [49]) estimated the worldwide extent of shifting cultivation in the early 1980s at 400 Mha [50], and an assessment made in 2011 with the aim of estimating greenhouse gas emissions arrived at 260 Mha for the 2000s [1]. [1]. The 270 first authors of these papers were listed and their email addresses were found. Australia, the Gulf States, arid areas in Africa) or where it disappeared several decades ago (e.g. Cultivation of the earth after clearing is usually accomplished by hoe or digging stick and not by plow. The negative effects of abusing shifting cultivation are devastating and far-reaching in degrading the environment and ecology of the affected region. An area of 1,000 Mha was mentioned by Davidson et al. Writing review & editing. It upsets the ecological balance as it disturbs many eco-systems of that region due to destruction of natural vegetation. Cultivation was also a traditional form of weed control. Visualization, Competing interests: The authors have declared that no competing interests exist. Our editors will review what youve submitted and determine whether to revise the article. 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. 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. Shifting cultivation (SC) is a traditional land-use system to ensure livelihood in the Amazon (Villa et al., 2020).The traditional SC have small areas (0.1-0.8 ha) and short cycles of agriculture (1-3 years) with high crop diversity followed by fallow periods of 2-7 years [Fig. 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. From droughts and wildfires to pests and pathogens, climate change is wreaking havoc on the world's forests. 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 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. 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. There's no doubt about it: the best thing we can do to fight climate change is keep forests standing. 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. At the same time, shifting cultivation was one of the most sensitive variables in their model runs (along with wood harvesting). Given that biomass regrows very quickly in the humid tropics, the GFC data set treats large shares of a field cleared for shifting cultivation and kept fallow for a relatively short period as deforestation. Panama, Guatemala) well into the 2000s. Yes Effects of Deforestation The major effect of deforestation on the environment is global warming and climatic change. 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. These negative effects can be identified in the form of localized deforestation, soil and nutrient loss, and invasion by weeds and other species. Supervision, The land takes many years to replenish just at the cost of providing yield for 2 to 3 years. Moderate warming and more carbon dioxide in the atmosphere may help some plants to grow faster. 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]. Meanwhile, about 54% people, living in the rural areas, are engaged in practicing it. Human influence on the land is accelerating because of rapid population growth and increasing food requirements. 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. They write new content and verify and edit content received from contributors. The red hatching in (B) indicates the 1/100 degree cells that were classified as having shifting cultivation. 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. Based on visual inspection of annual global deforestation data [8] from 2000 to 2014 and very high-resolution satellite imagery. The major disadvantage of Shifting Cultivation is that many trees in the forest are cut and this increases soil infertility and leads to soil . The imagery used for illustrative purpose in Fig 1 is based on Copernicus Sentinel 2 data from 2016. In soil-based agriculture, soil health is the most important foundation of a healthy farm ecosystem. Maps created in QGIS 2.16. https://doi.org/10.1371/journal.pone.0184479.g002. If the survey provided information about when (i.e. Regarding South and Southeast Asia, a meta-analysis by van Vliet et al. The visualization here shows a summary of some of the main global impacts: Food production accounts for over a quarter (26%) of global greenhouse gas emissions.
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