Browsing by Author "De Klerk, H. M."
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- ItemFree satellite data key to conservation(American Association for the Advancement of Science, 2018-07) Buchanan, G. M.; Beresford, A. E.; Hebblewhite, M.; Escobedo, F. J.; De Klerk, H. M.; Donald, P. F.; Escribano, P.; Koh, L. P.; Martínez-Lopez, J.; Pettorelli, N.; Skidmore, A. K.; Szantoi, Z.; Tabor, K.; Wegmann, M.; Wich, S.INTRODUCTION: Biodiversity is in crisis, with extinction rates orders of magnitude higher than background levels (1). Underfunded conservationists need to target their limited resources effectively. Over the past decade, satellite remote sensing has revolutionized our ability to monitor biodiversity globally, and is now used routinely, especially by nongovernmental organizations, to detect changes, set priorities, and target conservation action.
- ItemProbabilistic description of vegetation ecotones using remote sensing(Elsevier, 2018-07) De Klerk, H. M.; Burgess, N. D.; Visser, V.Ecotone transitions between vegetation types are of interest for understanding regional diversity, ecological processes and biogeographical patterns. Ecotones are seldom represented on vector, line-based vegetation maps, which imply an instantaneous change from one vegetation type to another. We use supervised, probabilistic classification of remotely sensed (RS) imagery to investigate the location, width and character of ecotones between acid Sandstone and alkaline Limestone fynbos on the Agulhas plain at the southern tip of Africa, known for rapid speciation of plants and exceptional plant biodiversity at the global scale. The resultant probability map, together with the probability graphs developed for a few transects across the transition, are able to map and describe (1) sharp, narrow ecotones (under five meters); (2) moderate ecotones that have a distinct band of transition (over a few hundred meters); and (3) complex ecotones that include slow transitions, interdigitated boundaries and outliers. The latter class of transitions include portions where vegetation types change sharply over a few meters, but due to the interdigitated boundaries they are mapped over hundreds of meters to a kilometre at a landscape scale. In this study area, our findings suggest that the character of the Agulhas limestone-acid ecotone is probably more complex than often noted. Moderate transitions and broad mosaics are difficult to indicate in a vector vegetation map, whereas RS probabilistic classifications can output images indicating core areas, important for key species and biodiversity pattern, and transitional zones, important for ecosystem processes and perhaps plant evolution, which distinction is important for conservation planning.
- ItemRemote sensing training in African conservation(Wiley, 2017-01) De Klerk, H. M.; Buchanan, GraemeThe potential of remote sensing (RS) to assist with conservation planning, implementation and monitoring is well described, and particularly relevant in African areas that are inaccessible due to terrain, finances or politics. We provide an African perspective on remote sensing (RS) training for conservation and ecology over the last decade through investigating (1) recent use of RS in African conservation literature, (2) use of RS in African conservation agencies, (3) RS training by African institutions and (4) RS capacity development by ad hoc events. Africa does not produce most of the research using RS in conservation and ecological studies conducted on Africa, with authors with correspondence addresses in the USA predominating (33% of a bibliometric analysis), although South Africa-based authors constituted 20% (with an increase between 2000 and 2015), Kenya 6% and Tanzania and Ethiopia 4% each. Ideally research should be conducted close to the point of use to ensure relevance and data residence in the country concerned. This is a point for attention, possibly through international funding to increase the capacity of African academic institutions to conduct research using RS to answer conservation questions. Part of this will need to include attention on data and software costs, internet speeds and human capacity. Data costs have been alleviated by free Landsat and MODIS data, and the Copernicus programs, but there is need for higher resolution imagery to be freely available for certain conservation projects. Open Source software may well offer a long-term solution to software costs. This would require that teaching is realigned to employer requirements, which are shifting in many countries and agencies from proprietary software to Open Source due to licensing costs. Low internet connectivity in many areas of Africa might limit the uptake of new data processing options that require connectivity, although over time these tools may become available to more users. However, human capacity is developing. Of the 72 academic institutions surveyed, a number of conservation programs supplied either tailored RS teaching or used ‘service modules’ to provide RS skills to young graduating conservation professionals, showing a recognition of the importance of RS in conservation in Africa. This study highlights the success of capacity development in Africa, and the increasing use of remote sensing for conservation in Africa.