explain the effects of shifting cultivation on the environment

Climate Change. For more information about PLOS Subject Areas, click There's no doubt about it: the best thing we can do to fight climate change is keep forests standing. No, Is the Subject Area "Africa" applicable to this article? 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. For large parts of Southeast Asia, the survey results point towards that the current swift decrease in shifting cultivation continues, and that a large share of the area under shifting cultivation will have disappeared by 2030, and the remaining pockets are likely to be almost entirely gone by 2060.Moreover, the survey results indicate trends for some specific Asian countries: Humid tropical Africa is probably the region for which developments are most difficult to predict due to limited data. Intensive agriculture has dominated the global food production . Mexico and Brazil) likely to see a fairly rapid decrease and disappearance. Writing review & editing, Affiliation https://doi.org/10.1371/journal.pone.0184479.g006. Areas drenched by irrigation can become waterlogged, creating soil conditions that poison plant roots through anaerobic decomposition. This paper presents the causes and consequences of shifting cultivation and its potential land use alternatives. The effects of shifting cultivation are devastating and far-reaching in degrading the environment and ecology of these regions. 2], while long cycles comprise fallow periods of more than 15 years (Villa et al., 2020; Villa et al., 2017 . The Neolithic Revolutionalso referred to as the Agricultural Revolutionis thought to have begun about 12,000 years ago. Nonetheless, it is more evidence-based than the 1,000 Mha of unclear origin that are repeatedly cited in the literature (e.g. Most plants and animals live in areas with very specific climate conditions, such as temperature and rainfall patterns, that enable them to thrive. Yes The history of shifting cultivation is as old as the history of agriculture itself. 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. 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]. However, the occurrence of shifting cultivation within most of the individual one-degree cells is very low, meaning that it is a minor component of the overall landscape. Formal analysis, Writing original draft, [68]). Concludes by addressing the need to protect and conserve the natural forests and wild life. Solution Shifting Cultivation: Slash-and-burn cultivation is another name for shifting cultivation. 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 increase of shifting cultivation in Myanmar shown in Fig 6 is due to a marked underestimation in the Butler map, which can possibly be explained by the limited availability of information about Myanmar after the military government came to power in 1962. Plants, Animals, and Ecosystems. 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. Half of the world's habitable land is used for agriculture. While keeping in mind the inherent limitations of these predictions, we can identify a number of more specific patterns. 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. Maps created in QGIS 2.16. https://doi.org/10.1371/journal.pone.0184479.g002. 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. There was a bias towards responses from researchers who worked in Southeast Asia (see Fig 3); but this is also the world region where most research on shifting cultivation has been done, whereas Africa has the fewest studies and is clearly under-represented in light of the considerable occurrence of shifting cultivation there [17,44]. 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 agriculture has frequently been attacked in principle because it degrades the fertility of forestlands of tropical regions. We estimate that shifting cultivation landscapes currently cover roughly 280 million hectares worldwide, including both cultivated fields and fallows. Using recent regional and national automated classification of shifting cultivation as reference (e.g. 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 figure was elaborated by the first author using ArcGIS 10.4. https://doi.org/10.1371/journal.pone.0184479.g003. However, more severe warming, floods, and drought may reduce yields. https://www.britannica.com/topic/shifting-agriculture. Degradation is the gradual decline of forested areas that does not result in complete deforestation. Writing original draft, Roles Describes the cultivation systems employed and the problems generated erosion, burning, harm to indigenous plants and animals. Mining An increased demand for minerals is also driving the mining industry to destroy forests. For large parts of insular Southeast Asia and South Asia (e.g. The map shows that shifting cultivation is still present across large areas of the humid tropics. 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). 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. 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. Writing review & editing, Affiliation Copyright: 2017 Heinimann et al. The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more commonly, when the field is overrun by weeds. 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]. 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. However, sustainable agriculture, which uses methods that protect the environment, public . Methodology, This approach, however, suffers from the shortcoming that land cover data are of very limited use in estimating land use practices, which is acknowledged by Silva et al. In Mexico, however, the trend has been towards decreasing areas under shifting cultivation. This trend, which was also identified by van Vliet et al. The study by Silva et al. The earlier 15-20 years cycle of shifting cultivation on a particular land has reduced to 2-3 years now. Panama, Guatemala) well into the 2000s. [2] included shifting cultivation in a global harmonization of land use states and transitions from past to future: they found only one (hand-drawn) global map of shifting cultivation, in a book on economic geography dating from 1980 [13]. Our editors will review what youve submitted and determine whether to revise the article. Both conditions apply to considerable parts of Central Africa. The area of interest ranges from 30S and 30N (6,704 one-degree cells on landmass), while the area investigated includes 2,817 cells. The red box marks the extent of Fig 2D and Fig 2E. 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. 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. The research presented here contributes to the objectives of the Global Land Programme (glp.earth). 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. The map is binary (presence-absence), with no information on occurrence frequency or land-use intensity. These systems are naturally suited for harsh environments and fragile ecosystems of the tropics. Methodology, Visualization, in the Amazon and parts of the Democratic Republic of the Congo), or a residual form of cultivation in landscapes that have mostly been transformed to other land uses (such as permanent agriculture or tree crops, e.g. - Madagascar: Shifting cultivation is expected to remain widespread, especially along the eastern escarpment, until well beyond 2030. [52]; the latter source, however, does not provide this information, so the 1,000 Mha claim seems to be unfounded. b. 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]. First, an area of fallow forest is cleared for cultivation. This visualization is based on the estimation of landscapes showing signs of shifting cultivation around 2010 (Fig 5) as base year and estimated decreases of shifting cultivation (Table 3) based on the expert surveys and observed trend between the Butler map and our 2010. Institute of Geography, University of Bern, Bern, Switzerland, 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. Formal analysis, The climate of most European countries is wet Table of Content Why are Forests Important? Citation: Heinimann A, Mertz O, Frolking S, Egelund Christensen A, Hurni K, Sedano F, et al. Click through the PLOS taxonomy to find articles in your field. The system is destabilized by long cultivation and short fallow periods. [1] indicate 110 Mha for this region, but unlike FAO they did not include Mexico in their estimation. Depletion of Nutrients The primitive style of framing like slash and burn decreases the organic matter from the soil. [51] citing Sanchez et al. No, Is the Subject Area "Earth systems" applicable to this article? (2017) A global view of shifting cultivation: Recent, current, and future extent. 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. Methodology, Eutrophication is considered to be a serious environmental concern since it often results in the . (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. The accuracy levels of our classification were high with an overall accuracy above 87%. 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]. At the regional scale, an assessment by Spencer [45] provides a slightly more differentiated picture of the presence of shifting cultivation practices in Asia. shifting agriculture, system of cultivation that preserves soil fertility by plot (field) rotation, as distinct from crop rotation. 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. Analysis of Landsat data back to Landsat4 (launched in 1982) could provide more than 30 years of pan-tropical records, covering a time of significant change in the distribution of shifting cultivation across the humid tropics and perhaps also in the length of fallow periods. 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. 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. Since there have been many controversies about the impact of jhum cultivation the study was done to analyse the current situation of the practice of shifting cultivation as perceived by the local people of Mokokchung village. Taking into consideration the stratification criteria, 328 one-degree cells were randomly selected to be validated. But information about such landscapes is urgently needed to improve the . of Energy, grant number DE-SC0012972, and the Global Land Project Grant from the University of Copenhagen. 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. On this basis, we can provide a preliminary overview of regional and national trends in the development of the extent of shifting cultivation over the past 40 to 50 years. 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). Nobody knows how many people today depend on shifting cultivation globally [22]. 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. 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. 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. 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]. 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. 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. 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. The number of estimates of areas under shifting cultivation at regional and national scales in the literature is also very limited. Overall, a decrease after 2030 and disappearance after 2060 is expected. 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. Why poison ivy is an unlikely climate change winner. 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. Shifting cultivation remains widespread, despite decreases in its extent over the last four to five decades. This causes degradation of land, soil erosion, etc. The ranges are based on the expert survey and observed trends between the Butler map and our 2010 classification (Fig 5). The global food system is in crisis. Solution: a. India is an agricultural country. Climate change has caused increased heat, drought, and insect outbreaks. Habitable land is land that is ice- and desert-free. (Fig 2A): the global distribution of the stratified sample of the 328 one-degree cells used in the validation data set. Predicting future trends in the development of any form of land use requires extreme caution [23,69]. Meanwhile, about 54% people, living in the rural areas, are engaged in practicing it. In some specific areas, especially in Central Africa, it is likely to increase over the next decade before it begins to decline. Data curation, (Fig 2B): Location of the one-degree cell of Fig 2C - 2E. 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. Fig 1B to Fig 1E show examples of different zoom levels used to decide whether the pattern in the GFC data is indeed related to shifting cultivation Fig 1E (showing pattern of clearing for the current year of cultivation and different stages of fallow) or not Fig 1D (larger scale clearings with young rubber). Writing review & editing. 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. For Southeast Asia, Schmidt-Vogt et al. Given the unavailability of automated approaches to detect shifting cultivation at a global level and deliver data in a timely manner for ongoing earth system modeling, we have used a visual interpretation approach to detect shifting cultivation. By contrast, we expect that shifting cultivation will persist for a longer time in Africa, especially in Central Africa. The impacts of traditional agriculture on Environment are discussed below: 1. 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 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. 5 Ways Climate Change Impacts Forests. 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. Shifting cultivation systems are commonly associated with rural poverty and forest degradation. Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, United States of America, 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. The imagery used for illustrative purpose in Fig 1 is based on Copernicus Sentinel 2 data from 2016. Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen K, Denmark, Roles 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.

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