A global view of shifting cultivation: Recent, current, and future extent

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. 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. 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. The accuracy levels of our classification were high with an overall accuracy above 87%. 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 an expert survey, we make a first attempt at estimating past trends as well as possible future trends in the global distribution of shifting cultivation until the end of the 21st century. With 62% of the investigated one-degree cells in the humid and sub-humid tropics currently showing signs of shifting cultivation—the majority in the Americas (41%) and Africa (37%)—this form of cultivation remains widespread, and it would be wrong to speak of its general global demise in the last decades. We estimate that shifting cultivation landscapes currently cover roughly 280 million hectares worldwide, including both cultivated fields and fallows. While only an approximation, this estimate is clearly smaller than the areas mentioned in the literature which range up to 1,000 million hectares. 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

Mathematical modelling of fibre-enhanced perfusion inside\ud a tissue-engineering bioreactor

We develop a simple mathematical model for forced flow of culture medium through a porous scaffold in a tissue- engineering bioreactor. Porous-walled hollow fibres penetrate the scaffold and act as additional sources of culture medium. The model, based on Darcy’s law, is used to examine the nutrient and shear-stress distributions throughout the scaffold. We consider several configurations of fibres and inlet and outlet pipes. Compared with a numerical solution of the full Navier–Stokes equations within the complex scaffold geometry, the modelling approach is cheap, and does not require knowledge of the detailed microstructure of the particular scaffold being used. The potential of this approach is demonstrated through quantification of the effect the additional flow from the fibres has on the nutrient and shear-stress distribution

Participation of older people in recreation movement anda sense of quality of life

An analysis concerns the level of the sense of quality of life among the people 60+. There has been shown the evaluation of sense of satisfaction with life on a global scale and in selected areas of quality of life among older people not participating in physical recreation at all and four weeks after taking up physical recreation. Test results: The vast majority of respondents after the participation in recreation is happy with their physical shape, contact with friends, relationships with family and peace of mind. Adoption of physical activity impact on the perception of the ability to perform the duties of everyday life and consciousness of energy level and the will to manage their own lives, including leisure activities according to their own tastes. Conclusion of the study: Promotion of various forms of physical activities among the elderly can contribute to improvement of their quality of life

Preliminary estimates of changes in the occurrence of shifting cultivation between today and 2030, 2060 and 2090.

<p>This visualization is based on the estimation of landscapes showing signs of shifting cultivation around 2010 (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184479#pone.0184479.g005" target="_blank">Fig 5</a>) as base year and estimated decreases of shifting cultivation (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184479#pone.0184479.t003" target="_blank">Table 3</a>) based on the expert surveys and observed trend between the Butler map and our 2010. This figure was elaborated by the first author using ArcGIS 10.4.</p

Numbers and percentages of one-degree cells studied that showed signs of shifting cultivation (SC) or not (No SC), as well as percentages of cells showing signs of shifting cultivation in the various occurrence classes, per region.

<p>The area of interest ranges from 30°S and 30°N (6,704 one-degree cells on landmass), while the area investigated includes 2,817 cells. 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 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184479#pone.0184479.g005" target="_blank">Fig 5</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184479#sec002" target="_blank">Method</a> section).</p

Butler (1980) map of areas where land use includes “primitive subsistence agriculture,” which in the humid tropics largely consists of shifting cultivation (reproduction by first author using ArcGIS 10.4 based on Hurtt et al. [2]).

<p>Butler (1980) map of areas where land use includes “primitive subsistence agriculture,” which in the humid tropics largely consists of shifting cultivation (reproduction by first author using ArcGIS 10.4 based on Hurtt et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184479#pone.0184479.ref002" target="_blank">2</a>]).</p

Estimation of landscapes showing signs of shifting cultivation around 2010 between 30°S to 30°N.

<p>Based on visual inspection of annual global deforestation data [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184479#pone.0184479.ref008" target="_blank">8</a>] from 2000 to 2014 and very high-resolution satellite imagery. Areas in which shifting cultivation can be assumed to have never existed or disappeared decades ago have been excluded from the analysis (dark gray). This figure was elaborated by the first author using ArcGIS 10.4.</p

Identification of spatio-temporal pattern based on GFC global annual deforestation data [8] and very high–resolution satellite imagery.

<p>Fig 1A shows a one-degree square of northern Laos. The colored pixels indicate clearings in different years between 2000 and 2014 as recorded in the GFC data set [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184479#pone.0184479.ref008" target="_blank">8</a>]. 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). The imagery used for illustrative purpose in Fig 1 is based on Copernicus Sentinel 2 data from 2016. Maps created in QGIS 2.16.</p