PLOS ONE promises fair, rigorous peer review, But soil health is negatively impacted by industrial agriculture practices like monocropping, synthetic fertilizers, pesticides and more. Formal analysis, More widespread signs of shifting cultivation were found mostly in small pockets, with the exception of larger areas in Central Africa (e.g. 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. The map shows that shifting cultivation is still present across large areas of the humid tropics. After eliminating papers that were not related to recent shifting cultivation in the tropics (e.g. In eastern and southern Africa, shifting cultivation is still present, but not very common, with particularly low occurrences in Kenya and Tanzania. It is a form of farming practice that entails clearing a land parcel by felling and burning trees. Fig 1 illustrates the procedure we used for this visual inspection. 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. 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. 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. Extreme heat, heavy downpours, and flooding will affect infrastructure, health, agriculture, forestry, transportation, air and water quality, and more. 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. Road Building The Transamazon Highway has allowed increased access to the Amazon Rainforest. here. 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. 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. Depletion of Nutrients The primitive style of framing like slash and burn decreases the organic matter from the soil. The climate of most European countries is wet Climate change is a leading cause of deforestation. Shifting cultivation decreases the activities of useful microorganisms found in the soil. The areas referred to as the rural complex may be used as a proxy for the presence of shifting cultivation. Click through the PLOS taxonomy to find articles in your field. 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). The evil effects of shifting cultivation are devastating and far reaching in degrading the environment and ecology of this region. 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 stratified validation sample design was chosen considering the distribution of the validation samples per occurrence class and the spatial distribution per continents. Writing original draft, We compared this result to Butlers (1980) binary (presence or absence) map of shifting cultivation, gridded into one-degree cells. b. 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. 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. We are very grateful to Laura Ebneter, Manuel Abebe, Lukas Wuersch and Boris Fuhrer for their support in interpreting the satellite imagery and to Marlne Tibeault for the language editing. Yes In Central America, shifting cultivation is still widespread, and both Fig 6 and the survey results indicate an increase in some areas (e.g. Mining An increased demand for minerals is also driving the mining industry to destroy forests. 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. Such areas are found in parts of Southeast Asia (e.g. No, Is the Subject Area "Surveys" applicable to this article? Yes Secondly, the detection and monitoring of complex shifting cultivation mosaics using automated remote sensing approaches remains challenging [33,38,39] and the mentioned small spatio-temporal signature of vegetation clearings and regrowth is very specific to shifting cultivation and visual interpretation is therefore suitable [40]. This trend, which was also identified by van Vliet et al. 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. Methodology, https://doi.org/10.1371/journal.pone.0184479.s001. 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. Climate change will bring more frequent and severe extreme weather events, including extreme precipitation, wind disturbance, heat waves, and drought. [1]. Predicting future trends in the development of any form of land use requires extreme caution [23,69]. Yes The ashes are then mixed with the soil. Degradation is the gradual decline of forested areas that does not result in complete deforestation. But information about such landscapes is urgently needed to improve the . Methodology, [68]). Writing original draft, For more information about PLOS Subject Areas, click 70% of global freshwater withdrawals are used for agriculture 2. This has led to a paucity of global information on certain land use systems, including shifting cultivation at the global level. 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. 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. 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. 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. 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. All answers were anonymous and cannot be traced back to the individual expert. 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 negative effects of abusing shifting cultivation are devastating and far-reaching in degrading the environment and ecology of the affected region. 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. 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. 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%. See also slash-and-burn agriculture. Meanwhile, the area under shifting cultivation has decreased by 71.22% from 1997 and forest cover has decreased by 4.41% during the period. - Papua New Guinea: Shifting cultivation may persist well into the second half of this century, perhaps even until 2090. The earlier 15-20 years cycle of shifting cultivation on a particular land has reduced to 2-3 years now. This figure was elaborated by the first author using ArcGIS 10.4. https://doi.org/10.1371/journal.pone.0184479.g007. [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]. In some specific areas, especially in Central Africa, it is likely to increase over the next decade before it begins to decline. 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. Researchers are currently developing automated approaches that are capable of processing decades of Landsat data and detecting the spatio-temporal patterns of shifting cultivation. While only an approximation, this estimate is clearly smaller than the areas mentioned in the literature which range up to 1,000 million hectares. However, sustainable agriculture, which uses methods that protect the environment, public . 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. 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. 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. Meanwhile, about 54% people, living in the rural areas, are engaged in practicing it. 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 analysis presented is primarily qualitative with a supplementary quantitative analysis of the causes of forest . 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. 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. Yes Shifting cultivation is a rotational agriculture and forest management system practiced sequentially on the same plot of land. While keeping in mind the inherent limitations of these predictions, we can identify a number of more specific patterns. Methodology, 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. Writing review & editing, Affiliation [1] indicate 110 Mha for this region, but unlike FAO they did not include Mexico in their estimation. However, this future may also provide better opportunities for production and income generation if development efforts are sensitive to the needs of shifting cultivators [73,74]. Thus that abandoned land then gets ample . [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. 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]. 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. 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. [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. Other Causes of Deforestation Forest Fires Fires are a natural part of the lifecycle of many forests, clearing the way for younger, smaller growth. 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. 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. If the survey provided information about when (i.e. 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. It coincided with the end of the last ice age and the beginning of the. https://doi.org/10.1371/journal.pone.0184479.g004. - Vietnam and Laos: Shifting cultivation is likely to be greatly reduced by 2030 and completely gone by 2060. 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. 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. Moreover, it is not possible to know in detail how the respondents arrived at their assessment of past and future extents of shifting cultivation. Conceptualization, 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]. The accuracy levels of our classification were high with an overall accuracy above 87%. https://doi.org/10.1371/journal.pone.0184479.t001. Nearly two-thirds of its population depends directly on agriculture for its livelihood. This is reflected both in the comparison of the two spatial data sets (Fig 6) and in the survey responses. Department of Geographical Sciences, University of Maryland, College Park, United States of America, Roles Peninsular Malaysia, central and southern Thailand) [28]. Conceptualization, 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. 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. Citation: Heinimann A, Mertz O, Frolking S, Egelund Christensen A, Hurni K, Sedano F, et al.
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