Effects of Deforestation The major effect of deforestation on the environment is global warming and climatic change. Climate change will also worsen a range of risks to the Great Lakes. 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. No, Is the Subject Area "Deforestation" applicable to this article? At the same time, shifting cultivation was one of the most sensitive variables in their model runs (along with wood harvesting). More widespread signs of shifting cultivation were found mostly in small pockets, with the exception of larger areas in Central Africa (e.g. This is called shifting cultivation. Of the remaining 225 authors, 72 responded and 49 provided usable information (see S1 File). Writing review & editing, Affiliation [24], who in turn had cited Dixon et al. [1]. 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. Describes the cultivation systems employed and the problems generated erosion, burning, harm to indigenous plants and animals. [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]. Human expansion throughout the world caused that agriculture is a dominant form of land management globally. 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. https://doi.org/10.1371/journal.pone.0184479.g004. 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. [17], contrasts with developments in other parts of Africa, where decreases and the disappearance of areas under shifting cultivation have dominated over the last two decades. In fact, they should be understood as best guesses about general patterns rather than temporally and spatially accurate predictions, as land use transitions often happen suddenly, causing abrupt changes over large areas [23]. 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. 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. Let us know if you have suggestions to improve this article (requires login). Methodology, 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. 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. However, more severe warming, floods, and drought may reduce yields. Improvements in mapping the extent of shifting cultivation and trends in its development may be expected in the near future. 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. Why poison ivy is an unlikely climate change winner. Fig 2 illustrates this process for one sample cell. While keeping in mind the inherent limitations of these predictions, we can identify a number of more specific patterns. While every effort has been made to follow citation style rules, there may be some discrepancies. The classic studies on shifting cultivation in Africa [4648] do not provide any area data for the continent, and for Central and South America we were unable to find any regional-scale past area estimation. The map shows that shifting cultivation is still present across large areas of the humid tropics. 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. By contrast, we expect that shifting cultivation will persist for a longer time in Africa, especially in Central Africa. Laos, Vietnam) over the past 15 to 25 years is not reflected in this comparison. Writing review & editing, Affiliation Overall, a decrease after 2030 and disappearance after 2060 is expected. 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. Based on our expert survey and historical trends we estimate a possible strong decrease in shifting cultivation over the next decades, raising issues of livelihood security and resilience among people currently depending on shifting cultivation. https://doi.org/10.1371/journal.pone.0184479.t001. 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. Thus that abandoned land then gets ample . Competing interests: The authors have declared that no competing interests exist. 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. Yes Eutrophication is the process in which a water body becomes overly enriched with nutrients, leading to plentiful growth of simple plant life. 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]. 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 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. 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. 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. 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 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. Writing original draft, There's no doubt about it: the best thing we can do to fight climate change is keep forests standing. Methodology, https://doi.org/10.1371/journal.pone.0184479.t003. 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. Applying these largely survey-based estimates (Table 3) to our map of the extent of shifting cultivation in 2010 (Fig 5), we were able to visually display our rough predictions of developments in the extents of shifting cultivation by 2030, 2060, and 2090 (Fig 7). Our predictions of future extents of shifting cultivation are, of course, speculative. in parts of Southeast Asia). This has led to a paucity of global information on certain land use systems, including shifting cultivation at the global level. The climate of most European countries is wet The uptick in mosquito-borne diseases, for example, or the rapid spread of roya, an insidious plant disease that threatens our supply of coffee are all indirect consequences of deforestation and global warming. Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen K, Denmark, Roles Extreme precipitation events can disturb plant growth, particularly in recently burned forests, and make plants more vulnerable to flooding and soils to erosion. 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. The Neolithic Revolutionalso referred to as the Agricultural Revolutionis thought to have begun about 12,000 years ago. However, future climate projections and carbon budget estimates on carbon land sinks and land use emissions based on earth system models depend on such predictions as input, so any attempt to provide an evidence base for them is certainly a worthwhile improvement compared to relying on historical trends or static futures. As for Africa, we found only one recent national study, on the Democratic Republic of the Congo [36]. Formal analysis, It ensures the forest will recover. All answers were anonymous and cannot be traced back to the individual expert. 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. 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. 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 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. An online questionnaire was designed and sent to these 270 authors in September 2015 using survey monkey. 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. Table of Content Why are Forests Important? Habitable land is land that is ice- and desert-free. 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. The accuracy levels of our classification were high with an overall accuracy above 87%. 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. 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. 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%). (Fig 2B): Location of the one-degree cell of Fig 2C - 2E. 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 ashes are then mixed with the soil. The analysis presented is primarily qualitative with a supplementary quantitative analysis of the causes of forest . c. Agriculture is the main stay of India's economy. 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. This left us with 2,817 one-degree cells, which we then further investigated. Panama, Guatemala) well into the 2000s. 70% of global freshwater withdrawals are used for agriculture 2. This is the case for Peninsular Malaysia [28], parts of Sumatra [60], Yunnan Province in southern China [61]and the southern part of the Brazilian Amazon [62], for example. 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%). Areas drenched by irrigation can become waterlogged, creating soil conditions that poison plant roots through anaerobic decomposition. 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. At present, net area sown in Mizoram State is only 5.5%, of which, 16.9% area is devoted to shifting cultivation. The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more commonly, when the field is overrun by weeds. and the overall accuracy and the Cohens kappa coefficient were calculated. The colored pixels indicate clearings in different years between 2000 and 2014 as recorded in the GFC data set [8]. 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. Road Building The Transamazon Highway has allowed increased access to the Amazon Rainforest. 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. It is a sustainable method of farming in the rainforest. - Madagascar: Shifting cultivation is expected to remain widespread, especially along the eastern escarpment, until well beyond 2030. 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. 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]. 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. 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. PLOS ONE promises fair, rigorous peer review, This trend, which was also identified by van Vliet et al. 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 . Depletion of Nutrients The primitive style of framing like slash and burn decreases the organic matter from the soil. - Vietnam and Laos: Shifting cultivation is likely to be greatly reduced by 2030 and completely gone by 2060. 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. Disadvantages of Shifting cultivation: Deforestation Loss of fertility of a specific site Soil erosion Tree burning generates air pollution. The principle of cultivation is to turn the soil into a fine tilth to provide the ideal environment for seeds to germinate. 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]. 1. Formal analysis, Moderate warming and more carbon dioxide in the atmosphere may help some plants to grow faster. According to Olofsson et al. When the soil begins to turn infertile (usually after 3-5 years) the people move on. No source is reported for the map, but most likely it builds on a number of regional studies that was carried out between the 1940s and the 1970s, as well as general knowledge of where shifting cultivation and other extensive smallholder farming systems were found. [1], possibly owing to the scale (1-km resolution) of the GLC2000 data sets. 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. In Mexico, however, the trend has been towards decreasing areas under shifting cultivation. 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. Peninsular Malaysia, central and southern Thailand) [28]. 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. For large parts of insular Southeast Asia and South Asia (e.g. Other Causes of Deforestation Forest Fires Fires are a natural part of the lifecycle of many forests, clearing the way for younger, smaller growth. Venezuela [67]), and Madagascar [68]. Concludes by addressing the need to protect and conserve the natural forests and wild life. Forest and trees play an important role in balancing the environment. 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. 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. No, Is the Subject Area "Africa" applicable to this article? Writing original draft, It does so by following natural cycles, recycling nutrients and water, while omitting excessive use of agricultural chemicals. Formal analysis, 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. 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. Soil is the foundation of most types of agriculture. - Shifting cultivation also destroys the habitat of wild animals at large. 2030, 2060, 2090) shifting cultivation was expected to disappear completely from a specific country (n = 21), all one-degree cells having their centroid within that country where classified as having zero occurrence of shifting cultivation after that time, regardless of the above-described gradual decrease. Roles Visualization, In Central America, shifting cultivation is still widespread, and both Fig 6 and the survey results indicate an increase in some areas (e.g. 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. 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. No, Is the Subject Area "Surveys" applicable to this article? - 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. Our point of departure is a global map of the distribution of primitive subsistence agriculture produced by Butler in 1980 [13], a visual inspection of the distribution of shifting cultivation based on the 20002014 Global Forest Change (GFC) data set [8] and very highresolution satellite imagery, as well as an expert survey. Institute of Geography, University of Bern, Bern, Switzerland, [1] indicate 110 Mha for this region, but unlike FAO they did not include Mexico in their estimation. It coincided with the end of the last ice age and the beginning of the. Based on visual inspection of annual global deforestation data [8] from 2000 to 2014 and very high-resolution satellite imagery. Writing original draft, The validation of shifting cultivation mapping is generally challenging due to the lack of reference data [41,42]. Furthermore we wish to express our gratitude to the two reviewers as well as the editor for the very useful comments and inputs. Taking into consideration the stratification criteria, 328 one-degree cells were randomly selected to be validated. Validation, The earlier 15-20 years cycle of shifting cultivation on a particular land has reduced to two or three years now. The ranges are based on the expert survey and observed trends between the Butler map and our 2010 classification (Fig 5). Yucatan Peninsula [66], northern South America (e.g. 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. 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]. 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. Discover a faster, simpler path to publishing in a high-quality journal. 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). At the regional scale, an assessment by Spencer [45] provides a slightly more differentiated picture of the presence of shifting cultivation practices in Asia. 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. Solution Shifting Cultivation: Slash-and-burn cultivation is another name for shifting cultivation. Yes here. For India, Goswami et al. However, there are a number of other negative effects related to irrigation. 5 Ways Climate Change Impacts Forests. 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).
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