See also slash-and-burn agriculture. The analysis presented is primarily qualitative with a supplementary quantitative analysis of the causes of forest . Omissions? [3037]) would be insufficient, as they only cover very few of our one-degree cells and are not representative globally. Second, we combined the results of this comparison with those of our expert survey. Writing original draft, Let us know if you have suggestions to improve this article (requires login). Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, United States of America, Roles 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. The earlier 15-20 years cycle of shifting cultivation on a particular land has reduced to two or three years now. The map shows that shifting cultivation is still present across large areas of the humid tropics. Writing review & editing, Affiliation 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. https://www.britannica.com/topic/shifting-agriculture. Extreme weather. However, there are a number of other negative effects related to irrigation. 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. In addition to searching the Web of Science, we also consulted three major book publications that could be assumed to contain relevant information [2426]. For India, Goswami et al. Forest and trees play an important role in balancing the environment. Areas drenched by irrigation can become waterlogged, creating soil conditions that poison plant roots through anaerobic decomposition. Of the remaining 225 authors, 72 responded and 49 provided usable information (see S1 File). 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. [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, Is the Subject Area "South America" applicable to this article? While an area approximation of actual shifting cultivation landscapes based on our analysis is difficult due to the estimated and not measured shared of shifting cultivation of each one-degree cell we believe that, given the high accuracy of this estimation (see Table 2), a conservative estimate can nonetheless be derived by visually inspecting the cells and allocating reasonable shares of shifting cultivation landscape (currently cultivated fields plus all stages of fallows) to them as described in the methods section. These approaches, however, are still in the making and will require substantial resources. here. (2017) A global view of shifting cultivation: Recent, current, and future extent. 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 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]. 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]. 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. Extreme weather events like wildfires (which are responsible for an estimated 10% of degradation annually), droughts, and storm surges destroy millions of hectares of forest every year and their intensity is only increasing with global warming. Intensive agriculture has dominated the global food production . Intensive agriculture sometimes called factory farming lies at the heart of this emergency.. Cultivation of the earth after clearing is usually accomplished by hoe or digging stick and not by plow. For this reason, the known widespread decrease in the occurrence of shifting cultivation in Southeast Asia (e.g. Fig 1A shows a one-degree square of northern Laos. Meanwhile, the area under shifting cultivation has decreased by 71.22% from 1997 and forest cover has decreased by 4.41% during the period. The negative effects of abusing shifting cultivation are devastating and far-reaching in degrading the environment and ecology of the affected region. Overall, a decrease after 2030 and disappearance after 2060 is expected. 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. It coincided with the end of the last ice age and the beginning of the. Researchers are currently developing automated approaches that are capable of processing decades of Landsat data and detecting the spatio-temporal patterns of shifting cultivation. - 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. (Fig 2A): the global distribution of the stratified sample of the 328 one-degree cells used in the validation data set. Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen K, Denmark, Roles - India and Bangladesh: Shifting cultivation is estimated to disappear by 2030. [1], possibly owing to the scale (1-km resolution) of the GLC2000 data sets. Thus that abandoned land then gets ample . Nearly two-thirds of its population depends directly on agriculture for its livelihood. These systems are naturally suited for harsh environments and fragile ecosystems of the tropics. in parts of Southeast Asia). 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. 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 . About half of tropical deforestation is commonly explained by the expansion of traditional agriculture (shifting cultivation). 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. 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. Generally, the two approximations of areas under shifting cultivation are in fairly good agreement, especially when considering that the large differences in the arid areas of northern Africa, southern Angola, and Zambia and the high-mountain areas of eastern Bolivia are largely explained by the fact that Butler included other, non-shifting forms of extensive smallholder agriculture and that shifting cultivation in these areas based on the climatic condition never could have been widespread. 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. Plants, Animals, and Ecosystems. 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]. Shifting cultivation tends to persist when population density is low and when options for agricultural development or alternative livelihoods are limited [22,70,71]. 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. There's no doubt about it: the best thing we can do to fight climate change is keep forests standing. For Central and South America, the survey shows a mixed picture, with some areas being quite stable or even likely to experience expansion in the near future, and other areas (e.g. Writing original draft, 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. https://doi.org/10.1371/journal.pone.0184479, Editor: Benjamin Poulter, Montana State University Bozeman, UNITED STATES, Received: September 2, 2016; Accepted: August 24, 2017; Published: September 8, 2017. 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]. 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. Most plants and animals live in areas with very specific climate conditions, such as temperature and rainfall patterns, that enable them to thrive. However, the expert survey confirms that shifting cultivation has fully disappeared between the 1970s and the 2000s in various areas of mainland Southeast Asia, such as southern Thailand, Peninsular Malaysia, and China. 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. Climate change will also worsen a range of risks to the Great Lakes. Copyright: 2017 Heinimann et al. 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 . Each of the 328 sample one-degree cells was subdivided in cells of 1/100 degree by 1/100 degree, resulting in 10,000 verification cells per one-degree cell. 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. They write new content and verify and edit content received from contributors. In eastern and southern Africa, shifting cultivation is still present, but not very common, with particularly low occurrences in Kenya and Tanzania. 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. Road Building The Transamazon Highway has allowed increased access to the Amazon Rainforest. of Energy, grant number DE-SC0012972, and the Global Land Project Grant from the University of Copenhagen. In a second cluster of countriesLaos, Cambodia and Myanmarshifting cultivation areas have decreased drastically since 2000. Table of Content Why are Forests Important? This figure was elaborated by the first author using ArcGIS 10.4. https://doi.org/10.1371/journal.pone.0184479.g007. 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. The effects on seasons of a changing climate are already being seen across the country and vary region to region: temperatures have risen across seasons, growing seasons have become longer, precipitation patterns have changed, and extreme precipitation events have increased in frequency and severity. It does so by following natural cycles, recycling nutrients and water, while omitting excessive use of agricultural chemicals. Two steps enabled us to gain insights into larger recent (last 40 to 50 years) trends in the development of the global area under shifting cultivation. Effects of Deforestation The major effect of deforestation on the environment is global warming and climatic change. It is a sustainable method of farming in the rainforest. Due to its low productivity and incompatibility with most cash crops, shifting cultivation may lock farmers into 'land use' poverty traps. The Neolithic Revolutionalso referred to as the Agricultural Revolutionis thought to have begun about 12,000 years ago. Accordingly, they emphasized that the need for global data on annual global gridded land-use transitions from past-to-future presents a large and underdetermined problem [2]. Shifting cultivation causes a high national waste as it converts the green land into a barren land. 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. [24], who in turn had cited Dixon et al. 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 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). e. When the soil begins to turn infertile (usually after 3-5 years) the people move on. [3037]) such approaches cannot yet be up-scaled to global level due to data availability as well as computational limitations. Shifting cultivation, a resource-based subsistence farming, is no longer relevant because of the large population and its growing demands. Consequently, if further research (e.g. Yes Cultivation was also a traditional form of weed control. The number of estimates of areas under shifting cultivation at regional and national scales in the literature is also very limited. Comparison of these figures with the GLC2000-based area estimate for Laos of almost 11 Mha [1] underlines the problem of using the GLC2000 to estimate areas under shifting cultivation. The map shows large areas under such agriculture in Africa, tropical Central and South America, and Southeast Asia. This will be useful in improving the characterization of land surface and land use dynamics for earth system models and large-scale carbon and greenhouse gas accounting. Shifting cultivation, which is still prevalent in the uplands of eastern Bangladesh, contributes significantly to forest loss and is the main cause of land degradation. In this specific case 1088 or 10.88% of the 1/100 degree cells within the one-degree sample cell were detected as having shifting cultivation in the validation data sets. shifting agriculture, system of cultivation that preserves soil fertility by plot (field) rotation, as distinct from crop rotation. Shifting cultivation systems are commonly associated with rural poverty and forest degradation. The ranges are based on the expert survey and observed trends between the Butler map and our 2010 classification (Fig 5). 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. One of the most obvious consequences is the depletion of aquifers, river systems, and downstream ground water. 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). 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. b. For more information about PLOS Subject Areas, click No, Is the Subject Area "Agriculture" applicable to this article? Shifting cultivation is a rotational agriculture and forest management system practiced sequentially on the same plot of land. We would like to emphasize that the maps in Fig 7 are indeed very coarse estimates of the future global or continental extent of shifting cultivationand not an exact representation of where precisely it might be found in the near or far future. First, an area of fallow forest is cleared for cultivation. [1] indicate 110 Mha for this region, but unlike FAO they did not include Mexico in their estimation. It received 1 point in 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. https://doi.org/10.1371/journal.pone.0184479.g004. c. Agriculture is the main stay of India's economy. Moderate warming and more carbon dioxide in the atmosphere may help some plants to grow faster. Forests occupy nearly a third of Earth's land surface, providing humans and countless other species with a wide range of benefits and services from ecological functions such as water and air . According to Olofsson et al. We have nonetheless ventured to display our estimates in predictive maps because they are based on a spatially explicit analysis in 2010. The 270 first authors of these papers were listed and their email addresses were found. Institute of Geography, University of Bern, Bern, Switzerland, The research presented here contributes to the objectives of the Global Land Programme (glp.earth). Venezuela [67]), and Madagascar [68]. Methodology, Half of the world's habitable land is used for agriculture. After eliminating papers that were not related to recent shifting cultivation in the tropics (e.g. The system is destabilized by long cultivation and short fallow periods.
