Search Results - "Wessels, K J"

Can human-induced land degradation be distinguished from the effects of rainfall variability? A case study in South Africa by Wessels, K.J., Prince, S.D., Malherbe, J., Small, J., Frost, P.E., VanZyl, D.

“…Advanced Very High Resolution Radiometer (AVHRR), Normalized Difference Vegetation Index data (NDVI, 1 km 2, 1985–2003) and modeled net primary production…”
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Assessing the effects of human-induced land degradation in the former homelands of northern South Africa with a 1 km AVHRR NDVI time-series by Wessels, K.J, Prince, S.D, Frost, P.E, van Zyl, D

“…There is a pressing need for an objective, repeatable, systematic and spatially explicit measure of land degradation. In northeastern South Africa (SA), there…”
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Mapping land degradation by comparison of vegetation production to spatially derived estimates of potential production by Wessels, K.J., Prince, S.D., Reshef, I.

“…There is an urgent need for quantitative methods by which actual, as opposed to potential degradation can be mapped using spatially consistent criteria for…”
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Unsustainable fuelwood extraction from South African savannas by Wessels, K J, Colgan, M S, Erasmus, B F N, Asner, G P, Twine, W C, Mathieu, R, van Aardt, J A N, Fisher, J T, Smit, I P J

“…Wood and charcoal supply the majority of sub-Saharan Africa's rural energy needs. The long-term supply of fuelwood is in jeopardy given high consumption rates…”
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Detecting Land Cover Change Using an Extended Kalman Filter on MODIS NDVI Time-Series Data by Kleynhans, W, Olivier, J C, Wessels, K J, Salmon, B P, van den Bergh, F, Steenkamp, K

“…A method for detecting land cover change using NDVI time-series data derived from 500-m MODIS satellite data is proposed. The algorithm acts as a per-pixel…”
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Meta-Optimization of the Extended Kalman Filter's Parameters Through the Use of the Bias Variance Equilibrium Point Criterion by Salmon, B. P., Kleynhans, W., van den Bergh, F., Olivier, J. C., Marais, W. J., Grobler, T. L., Wessels, K. J.

“…The extraction of information on land cover classes using unsupervised methods has always been of relevance to the remote sensing community. In this paper, a…”
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Human-modified landscapes: patterns of fine-scale woody vegetation structure in communal savannah rangelands by FISHER, J. T., WITKOWSKI, E.T.F., ERASMUS, B.F.N., VAN AARDT, J., ASNER, G. P., WESSELS, K. J., MATHIEU, R.

“…Despite electrification, over 90% of rural households in certain areas of South Africa continue to depend on fuelwood, and this affects woody vegetation…”
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Mapping regional land cover with MODIS data for biological conservation: Examples from the Greater Yellowstone Ecosystem, USA and Pará State, Brazil by Wessels, K.J, De Fries, R.S, Dempewolf, J, Anderson, L.O, Hansen, A.J, Powell, S.L, Moran, E.F

“…The paper investigated the application of MODIS data for mapping regional land cover at moderate resolutions (250 and 500 m), for regional conservation…”
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Limits to detectability of land degradation by trend analysis of vegetation index data by Wessels, K.J., van den Bergh, F., Scholes, R.J.

“…This paper demonstrates a simulation approach for testing the sensitivity of linear and non-parametric trend analysis methods applied to remotely sensed…”
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The use of land facets as biodiversity surrogates during reserve selection at a local scale by Wessels, K.J., Freitag, S., van Jaarsveld, A.S.

“…Where species distribution data are inadequate reserve selection procedures have to rely on surrogate measures of biodiversity. The informativeness of land…”
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Applying Model Parameters as a Driving Force to a Deterministic Nonlinear System to Detect Land Cover Change by Salmon, B. P., Holloway, D. S., Kleynhans, W., Olivier, J. C., Wessels, K. J.

“…In this paper, we propose a new method for extracting features from time-series satellite data to detect land cover change. We propose to make use of the…”
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Relationship between herbaceous biomass and 1-km2 Advanced Very High Resolution Radiometer (AVHRR) NDVI in Kruger National Park, South Africa by Wessels, K. J., Prince, S. D., Zambatis, N., MacFadyen, S., Frost, P. E., Van Zyl, D.

“…The relationship between multi-year (1989-2003), herbaceous biomass and 1-km 2 Advanced Very High Resolution Radiometer (AVHRR) Normalized Difference…”
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A multicriteria approach to reserve selection: addressing long-term biodiversity maintenance by Reyers, B, Fairbanks, DHK, Wessels, K J, Van Jaarsveld, AS

“…Existing complementarity-based reserve selection techniquesconcerned with maximal biodiversity representation within minimum landarea do not necessarily ensure…”
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Impact of communal land use and conservation on woody vegetation structure in the Lowveld savannas of South Africa by Wessels, K.J., Mathieu, R., Erasmus, B.F.N., Asner, G.P., Smit, I.P.J., van Aardt, J.A.N., Main, R., Fisher, J., Marais, W., Kennedy-Bowdoin, T., Knapp, D.E., Emerson, R., Jacobson, J.

“…▶ Airborne LiDAR was used to characterize woody vegetation height distributions. ▶ Communal rangelands and fields were compared to adjacent conservation areas…”
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An evaluation of the gradsect biological survey method by Wessels, K. J., Jaarsveld, A. S. Van, Grimbeek, J. D., Linde, M. J. Van Der

“…Biological surveys are necessary to gather species distribution data for the identification of priority conservation areas. The rationale of the gradsect…”
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An assessment of biodiversity surrogacy options in the Limpopo Province of South Africa by Reyers, B., Wessels, K.J., van Jaarsveld, A.S.

“…Because of the inadequacy of existing biodiversity distribution data, surrogate measures for regional biodiversity have long been used in conservation area…”
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Vulnerability of South African animal taxa to climate change by Erasmus, Barend F. N., Van Jaarsveld, Albert S., Chown, Steven L., Kshatriya, Mrigesh, Wessels, Konrad J.

“…The responsiveness of South African fauna to climate change events is poorly documented and not routinely incorporated into regional conservation planning. We…”
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Management approaches of conservation areas: Differences in woody vegetation structure in a private and a national reserve by Fisher, J.T., Erasmus, B.F.N., Witkowski, E.T.F., van Aardt, J., Asner, G.P., Wessels, K.J., Mathieu, R.

“…Management approaches taken in protected areas will affect their ability and effectiveness to conserve biodiversity. MalaMala (a concession within Sabi Sand…”
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Incorporating land cover information into regional biodiversity assessments in South Africa by Wessels, K J, Reyers, B, Van Jaarsveld, AS

“…Anthropogenic natural habitat transformation presents the single most important threat to global biodiversity. Land cover data, based on Landsat Thematic…”
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Identification of potential conflict areas between land transformation and biodiversity conservation in north-eastern South Africa by Wessels, Konrad J, Reyers, Belinda, van Jaarsveld, Albert S, Rutherford, Mike C

“…Transformation of natural vegetation to other land-uses, such as crop cultivation and urban development, presents the most important threat to biodiversity…”
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