shifting agriculture, system of cultivation that preserves soil fertility by plot (field) rotation, as distinct from crop rotation. PLOS ONE promises fair, rigorous peer review, This trend, which was also identified by van Vliet et al. Our review of the more recent literature revealed surprisingly few studies containing regional or global estimates of areas under shifting cultivation. Improvements in mapping the extent of shifting cultivation and trends in its development may be expected in the near future. 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. However, more severe warming, floods, and drought may reduce yields. The history of shifting cultivation is as old as the history of agriculture itself. This figure was elaborated by the first author using ArcGIS 10.4. https://doi.org/10.1371/journal.pone.0184479.g003. Nobody knows how many people today depend on shifting cultivation globally [22]. 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]. 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. The producers and users accuracies were calculated for each occurrence class (< 1%; very low: 19%; low: 1019%; moderate: 2039%; high: 40%.) 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. Methodology, Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned while post-disturbance fallow vegetation is allowed to freely grow while the cultivator moves on to another plot. Areas drenched by irrigation can become waterlogged, creating soil conditions that poison plant roots through anaerobic decomposition. 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. These negative effects can be identified in the form of localized deforestation, soil and nutrient loss, and invasion by weeds and other species. Based on visual inspection of annual global deforestation data [8] from 2000 to 2014 and very high-resolution satellite imagery. Disadvantages of Shifting cultivation: Deforestation Loss of fertility of a specific site Soil erosion Tree burning generates air pollution. 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. Supervision, 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%. 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). Environment; Why poison ivy is an unlikely climate change winner. This is reflected both in the comparison of the two spatial data sets (Fig 6) and in the survey responses. within global land-use models) needs spatially explicit estimates of areas under shifting cultivation at intervals lying between the status shown in the Butler map (1960s to 1970s) and our estimations for 2010 (e.g. The areas referred to as the rural complex may be used as a proxy for the presence of shifting cultivation. 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%. The main outcomes presented in this study are maps showing the estimated presence of shifting cultivation at a one-degree resolution for the present, as well as, for the first time, estimations for 2030, 2060, and 2090. In some specific areas, especially in Central Africa, it is likely to increase over the next decade before it begins to decline. In addition to searching the Web of Science, we also consulted three major book publications that could be assumed to contain relevant information [2426]. At the regional scale, an assessment by Spencer [45] provides a slightly more differentiated picture of the presence of shifting cultivation practices in Asia. Let us know if you have suggestions to improve this article (requires login). While only an approximation, this estimate is clearly smaller than the areas mentioned in the literature which range up to 1,000 million hectares. Due to its low productivity and incompatibility with most cash crops, shifting cultivation may lock farmers into 'land use' poverty traps. Depletion of Nutrients The primitive style of framing like slash and burn decreases the organic matter from the soil. [24]). The recently launched Sentinel-2 instruments with their augmented repeat frequency will generally help to improve remote sensingbased analyses of the humid tropics, which are complicated by frequent and persistent cloud cover. An area of 1,000 Mha was mentioned by Davidson et al. The number of estimates of areas under shifting cultivation at regional and national scales in the literature is also very limited. - Vietnam and Laos: Shifting cultivation is likely to be greatly reduced by 2030 and completely gone by 2060. 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 . 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. Formal analysis, d. It accounts for 26% of the gross domestic product. No, Is the Subject Area "South America" applicable to this article? They write new content and verify and edit content received from contributors. 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 research presented here contributes to the objectives of the Global Land Programme (glp.earth). https://www.britannica.com/topic/shifting-agriculture. Conceptualization, This is called shifting cultivation. Thirty-eight email addresses were no longer functional and 7 authors declined to participate for various reasons. 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. Letting it dry and burning it off. Taking into consideration the stratification criteria, 328 one-degree cells were randomly selected to be validated. Maps created in QGIS 2.16. https://doi.org/10.1371/journal.pone.0184479.g001. Half of the world's habitable land is used for agriculture. 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]. The maps focus on the tropical parts of Central and South America, Africa, South and Southeast Asia, and the Southwest Pacific for two reasons: 1) These areas have the most biomass, causing land use transitions in these areas to have a particularly high impact on global carbon emissions; and 2) shifting cultivation is most widespread in these areas today [17]. 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 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. Cultivation (tillage) is a practice that has been introduced to Australia from Europe by our farming pioneers. By contrast, we expect that shifting cultivation will persist for a longer time in Africa, especially in Central Africa. 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. Shifting cultivation, a resource-based subsistence farming, is no longer relevant because of the large population and its growing demands. 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. 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. 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]. 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]. 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). We attribute it to 2010 for the sake of simplicity. Meanwhile, about 54% people, living in the rural areas, are engaged in practicing it. 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. 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. In soil-based agriculture, soil health is the most important foundation of a healthy farm ecosystem. Such areas are found in parts of Southeast Asia (e.g. In Mexico, however, the trend has been towards decreasing areas under shifting cultivation. Writing original draft, 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. The 270 first authors of these papers were listed and their email addresses were found. 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). It received 1 point in https://doi.org/10.1371/journal.pone.0184479.t001. 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. 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. 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. Institute of Geography, University of Bern, Bern, Switzerland, 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. The effects of shifting cultivation are devastating and far-reaching in degrading the environment and ecology of these regions. The areas newly classified as having shifting cultivation (blue in Fig 6) are more likely to have been missed in the Butler map than to represent actual new areas under shifting cultivation, as many of these regions are well known to still have significant shifting cultivation landscapes. b. Based on the spatio-temporal pattern of the GFC data (different colours denoted different year of clearings) and the patterns of clearing and regrowth in the very high resolution imagery (here Bing), a 1/100-degree cell is being classified as showing shifting cultivation or not. No, Is the Subject Area "Surveys" applicable to this article? Writing original draft, For more information about PLOS Subject Areas, click 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. Methodology, It is a sustainable method of farming in the rainforest. When the soil begins to turn infertile (usually after 3-5 years) the people move on. https://doi.org/10.1371/journal.pone.0184479.s001. Writing original draft, Roles 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. 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. here. [51] citing Sanchez et al. 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. The global shift towards this model of farming in the last sixty years has come with many costs. 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. Extreme weather. Fig 5 presents the results of our own visual approximation of the global extent of shifting cultivation around 2010 at a one-degree resolution, based on Hansen et al.s (2013) GFC data and very highresolution satellite imagery. Thus that abandoned land then gets ample . current practice of shifting cultivation in the region is an extravagant and unscientific form of land use. Moderate warming and more carbon dioxide in the atmosphere may help some plants to grow faster. However, there are a number of other negative effects related to irrigation. For more information about PLOS Subject Areas, click 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, 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). Of the remaining 225 authors, 72 responded and 49 provided usable information (see S1 File). 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 . To date, we know little about its worldwide extent, underlying spatial patterns, or global trends in its past and future development. Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, United States of America, Roles Centre for Development and Environment, University of Bern, Bern, Switzerland, Roles 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%). [52]; the latter source, however, does not provide this information, so the 1,000 Mha claim seems to be unfounded. Shifting cultivation is the major occupation and the main source of income of the marginal farmers ( Jhumias) in Mizoram. We then made an estimate of trends in occurrence of shifting cultivation for these aggregated regions for 2030, 2060 and 2090 also taking into account the historical trends between the Butler map and our 2010 classification. Plants, Animals, and Ecosystems. The imagery used for illustrative purpose in Fig 1 is based on Copernicus Sentinel 2 data from 2016. 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. 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. 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. Writing original draft, 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. This number certainly requires further validation before it can be claimed to be an adequate estimate of the global area under shifting cultivation. If and when the occurrence of shifting cultivation in a grid cell fell below 5% (mean value for very low), shifting cultivation was assumed to disappear in that grid cell. Mosaic landscapes under shifting cultivation, with their dynamic mix of managed and natural land covers, often fall through the cracks in remote sensingbased land cover and land use classifications, as these are unable to adequately capture such landscapes dynamic nature and complex spectral and spatial signatures. Roles Cultivation (the preparation of land for planting crops) on the plot is done for a few years until the fertility of the formerly burned land is reduced. Predicting future trends in the development of any form of land use requires extreme caution [23,69]. Shifting cultivation is a rotational agriculture and forest management system practiced sequentially on the same plot of land. The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more commonly, when the field is overrun by weeds. The search was performed in September 2015 and generated 316 results. Solution Shifting Cultivation: Slash-and-burn cultivation is another name for shifting cultivation. The map shows large areas under such agriculture in Africa, tropical Central and South America, and Southeast Asia. https://doi.org/10.1371/journal.pone.0184479.t003. This paper presents the causes and consequences of shifting cultivation and its potential land use alternatives.
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