Browsing Research Articles (Geography, Geoinformatics and Meteorology) by UP Author "Mathieu, Renaud"

Browsing Research Articles (Geography, Geoinformatics and Meteorology) by UP Author "Mathieu, Renaud"

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  • Aboveground biomass density models for NASA’s global ecosystem dynamics investigation (GEDI) lidar mission 
    Duncanson, Laura; Kellner, James R.; Armston, John; Dubayah, Ralph; Minor, David M.; Hancock, Steven; Healey, Sean P.; Patterson, Paul L.; Saarela, Svetlana; Marselis, Suzanne; Silva, Carlos E.; Bruening, Jamis; Goetz, Scott J.; Tang, Hao; Hofton, Michelle; Blair, Bryan; Luthcke, Scott; Fatoyinbo, Lola; Abernethy, Katharine; Alonso, Alfonso; Andersen, Hans-Erik; Aplin, Paul; Baker, Timothy R.; Barbier, Nicolas; Bastin, Jean Francois; Biber, Peter; Boeckx, Pascal; Bogaert, Jan; Boschetti, Luigi; Boucher, Peter Brehm; Boyd, Doreen S.; Burslem, David F.R.P.; Calvo-Rodriguez, Sofia; Chave, Jerome; Chazdon, Robin L.; Clark, David B.; Clark, Deborah A.; Cohen, Warren B.; Coomes, David A.; Corona, Piermaria; Cushman, K.C.; Cutler, Mark E.J.; Dalling, James W.; Dalponte, Michele; Dash, Jonathan; De-Miguel, Sergio; Deng, Songqiu; Ellis, Peter Woods; Erasmus, Barend Frederik Nel; Fekety, Patrick A.; Fernandez-Landa, Alfredo; Ferraz, Antonio; Fischer, Rico; Fisher, Adrian G.; Garcia-Abril, Antonio; Gobakken, Terje; Hacker, Jorg M.; Heurich, Marco; Hill, Ross A.; Hopkinson, Chris; Huang, Huabing; Hubbell, Stephen P.; Hudak, Andrew T.; Huth, Andreas; Imbach, Benedikt; Jeffery, Kathryn J.; Katoh, Masato; Kearsley, Elizabeth; Kenfack, David; Kljun, Natascha; Knapp, Nikolai; Kral, Kamil; Krucek, Martin; Labriere, Nicolas; Lewis, Simon L.; Longo, Marcos; Lucas, Richard M.; Main, Russell; Manzanera, Jose A.; Martínez, Rodolfo Vasquez; Mathieu, Renaud; Memiaghe, Herve; Meyer, Victoria; Mendoza, Abel Monteagudo; Monerris, Alessandra; Montesano, Paul; Morsdorf, Felix; Næsset, Erik; Naidoo, Laven; Nilus, Reuben; O’Brien, Michael; Orwig, David A.; Papathanassiou, Konstantinos; Parker, Geoffrey; Philipson, Christopher; Phillips, Oliver L.; Pisek, Jan; Poulsen, John R.; Pretzsch, Hans; Rudiger, Christoph; Saatchi, Sassan; Sanchez-Azofeifa, Arturo; Sanchez-Lopez, Nuria; Scholes, Robert; Silva, Carlos A.; Simard, Marc; Skidmore, Andrew; Sterenczak, Krzysztof; Tanase, Mihai; Torresan, Chiara; Valbuena, Ruben; Verbeeck, Hans; Vrska, Tomas; Wessels, Konrad; White, Joanne C.; White, Lee J.T.; Zahabu, Eliakimu; Zgraggen, Carlo (Elsevier, 2022-03)
    NASA’s Global Ecosystem Dynamics Investigation (GEDI) is collecting spaceborne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). This ...
  • Analysing surface energy balance closure and partitioning over a semi-arid savanna FLUXNET site in Skukuza, Kruger National Park, South Africa 
    Majozi, Nobuhle P.; Mannaerts, Chris M.; Ramoelo, Abel; Mathieu, Renaud; Nickless, Alecia; Verhoef, Wouter (European Geosciences Union, 2017-07-10)
    Flux towers provide essential terrestrial climate, water, and radiation budget information needed for environmental monitoring and evaluation of climate change impacts on ecosystems and society in general. They are also ...
  • Assessment of the mapping of fractional woody cover in southern African savannas using multi-temporal and polarimetric ALOS PALSAR L-band images 
    Urbazaev, Mikhail; Thiel, Christian; Mathieu, Renaud; Naidoo, Laven; Levick, Shaun R.; Smit, Izak P.J.; Asner, Gregory P.; Schmullius, Christiane (Elsevier, 2015-09)
    Woody vegetation cover affects several ecosystem processes including carbon and water cycling, energy fluxes, and fire regimes. In order to understand the dynamics of savanna ecosystems, information on the spatial ...
  • Biomass increases go under cover : woody vegetation dynamics in South African rangelands 
    Mograbi, P.J. (Penelope); Erasmus, Barend Frederik Nel; Witkowski, E.F.T. (Ed); Asner, G.P. (Gregory); Wessels, K.J. (Konrad); Mathieu, Renaud; Knapp, D.E. (David); Martin, R.E. (Roberta); Main, Russell; Boldgiv, Bazartseren (Public Library of Science, 2015-05-13)
    Woody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate ...
  • The effect of surface fire in Savannah systems in the Kruger National Park (KNP), South Africa, on the backscatter of C-band sentinel-1 images 
    Mathieu, Renaud; Main, Russell; Roy, David P.; Naidoo, Laven N.; Yang, Hannah (MDPI, 2019-06-27)
    Savannahs are mixed woody-grass communities where low-intensity surface fires are common, a ecting mostly the grass layer and rarely damaging trees. We investigated the e ect of surface fires in a savannah system in the ...
  • Estimating above ground biomass as an indicator of carbon storage in vegetated wetlands of the grassland biome of South Africa 
    Naidoo, Laven; Van Deventer, Heidi; Ramoelo, Abel; Mathieu, Renaud; Nondlazi, Basanda; Gangat, Ridhwannah (Elsevier, 2019-06)
    Wetlands store higher carbon content relative to other terrestrial ecosystems, despite the small extent they occupy. The increase in temperature and changes in rainfall pattern may negatively affect their extent and ...
  • Estimating fractional cover of plant functional types in African savannah from harmonic analysis of MODIS time-series data 
    Ibrahim, Sa’ad; Balzter, Heiko; Tansey, Kevin; Tsutsumida, Narumasa; Mathieu, Renaud (Taylor & Francis Group, 2018-01-28)
    Assessments of tree/grass fractional cover in savannahs using remote sensing are challenging due to the heterogeneous mixture of the two plant functional types. Time-series decomposition models can be used to characterize ...
  • Forest biomass retrieval approaches from earth observation in different biomes 
    Rodriguez-Veiga, Pedro; Quegan, Shaun; Carreiras, Joao; Persson, Henrik J.; Fransson, Johan E.S.; Hoscilo, Agata; Ziolkowski, Dariusz; Sterenczak, Krzysztof; Lohberger, Sandra; Stangel, Matthias; Berninger, Anna; Siegert, Florian; Avitabile, Valerio; Herold, Martin; Mermoz, Stéphane; Bouvet, Alexandre; Le Toan, Thuy; Carvalhais, Nuno; Santoro, Maurizio; Cartus, Oliver; Rauste, Yrjö; Mathieu, Renaud; Asner, Gregory P.; Thiel, Christian; Pathe, Carsten; Schmullius, Chris; Seifert, Frank Martin; Tansey, Kevin; Balzter, Heiko (Elsevier, 2019-05)
    The amount and spatial distribution of forest aboveground biomass (AGB) were estimated using a range of regionally developed methods using Earth Observation data for Poland, Sweden and regions in Indonesia (Kalimantan), ...
  • Fuelwood extraction intensity drives compensatory regrowth in African savanna communal lands 
    Mograbi, Penelope J.; Witkowski, Ed T.F.; Erasmus, Barend Frederik Nel; Asner, Gregory P.; Fisher, Jolene T.; Mathieu, Renaud; Wessels, K.J. (Konrad) (Wiley, 2019-01)
    Woody biomass remains the primary energy source for domestic use in the developing world, raising concerns about woodland sustainability. Yet woodland regenerative capacity and the adaptive response of harvesters to localised ...
  • Humans and elephants as treefall drivers in African savannas 
    Mograbi, Penelope J.; Asner, Gregory P.; Witkowski, Ed T.F.; Erasmus, Barend Frederik Nel; Wessels, K.J. (Konrad); Mathieu, Renaud; Vaughn, Nicholas R. (Wiley, 2017-11)
    Humans have played a major role in altering savanna structure and function, and growing land-use pressure will only increase their influence on woody cover. Yet humans are often overlooked as ecological components. Both ...
  • Hyper-temporal C-band SAR for baseline woody structural assessments in deciduous savannas 
    Main, Russell; Mathieu, Renaud; Kleynhans, Waldo; Wessels, K.J. (Konrad); Naidoo, Laven; Asner, Gregory P. (MDPI Publishing, 2016-08-17)
    Savanna ecosystems and their woody vegetation provide valuable resources and ecosystem services. Locally calibrated and cost effective estimates of these resources are required in order to satisfy commitments to monitor ...
  • Impact of soil reflectance variation correction on woody cover estimation in Kruger National Park using MODIS data 
    Ibrahim, Sa’ad; Balzter, Heiko; Tansey, Kevin; Mathieu, Renaud; Tsutsumida, Narumasa (MDPI Publishing, 2019-04-12)
    Please read abstract in the article.
  • Indirect estimation of structural parameters in South African forests using MISR-HR and LiDAR remote sensing data 
    Mathieu, Renaud; Wessels, K.J. (Konrad); Naidoo, Laven; Verstraete, Michel; Asner, Gregory; Main, Russell (MDPI Publishing, 2018-09)
    Forest structural data are essential for assessing biophysical processes and changes, and promoting sustainable forest management. For 18+ years, the Multi-Angle Imaging SpectroRadiometer (MISR) instrument has been ...
  • An intercomparison of satellite-based daily evapotranspiration estimates under different eco-climatic regions in South Africa 
    Majozi, Nobuhle P.; Mannaerts, Chris M.; Ramoelo, Abel; Mathieu, Renaud; Mudau, Azwitamisi E.; Verhoef, Wouter (MDPI Publishing, 2017-03-24)
    Knowledge of evapotranspiration (ET) is essential for enhancing our understanding of the hydrological cycle, as well as for managing water resources, particularly in semi-arid regions. Remote sensing offers a comprehensive ...
  • L-band synthetic aperture radar imagery performs better than optical datasets at retrieving woody fractional cover in deciduous, dry savannahs 
    Naidoo, Laven; Mathieu, Renaud; Main, Russell; Wessels, K.J. (Konrad); Asner, Gregory P. (Elsevier, 2016-10)
    Woody canopy cover (CC) is the simplesttwo dimensional metric for assessing the presence ofthe woody component in savannahs, but detailed validated maps are not currently available in southern African savannahs. A number ...
  • Mapping and monitoring fractional woody vegetation cover in the arid savannas of Namibia using LiDAR training data, machine learning, and ALOS PALSAR data 
    Wessels, Konrad; Mathieu, Renaud; Knox, Nichola; Main, Russell; Naidoo, Laven; Steenkamp, Karen (MDPI Publishing, 2019-11-11)
    Namibia is a very arid country, which has experienced significant bush encroachment and associated decreased livestock productivity. Therefore, it is essential to monitor bush encroachment and widespread debushing ...
  • Multi-phenology WorldView-2 imagery improves remote sensing of savannah tree species 
    Madonsela, Sabelo; Cho, Moses Azong; Mathieu, Renaud; Mutanga, Onisimo; Ramoelo, Abel; Kaszta, Zaneta; Van de Kerchove, Ruben; Wolff, Eléonore (Elsevier, 2017-06)
    Biodiversity mapping in African savannah is important for monitoring changes and ensuring sustainable use of ecosystem resources. Biodiversity mapping can benefit from multi-spectral instruments such as WorldView-2 with ...
  • Potential of Sentinel-2 spectral configuration to assess rangeland quality 
    Ramoelo, Abel; Cho, Moses; Mathieu, Renaud; Skidmore, Andrew K. (Society of Photo-optical Instrumentation Engineers (SPIE), 2015-08-07)
    Sentinel-2 is intended to improve vegetation assessment at local to global scales. Today, estimation of leaf nitrogen (N) as an indicator of rangeland quality is possible using hyperspectral systems. However, few studies ...
  • Savannah woody structure modelling and mapping using multi-frequency (X-, C- and L-band) synthetic aperture radar data 
    Naidoo, Laven; Mathieu, Renaud; Main, Russell; Kleynhans, Waldo; Wessels, K.J. (Konrad); Asner, Gregory P.; Leblon, Brigitte (Elsevier, 2015-07)
    Structural parameters of the woody component in African savannahs provide estimates of carbon stocks that are vital to the understanding of fuelwood reserves, which is the primary source of energy for 90% of households ...
  • Seasonal separation of African savanna components using WorldView-2 imagery : a comparison of pixel- and object-based approaches and selected classification algorithms 
    Kaszta, Zaneta; Van De Kerchove, Ruben; Ramoelo, Abel; Cho, Moses Azong; Madonsela, Sabelo; Mathieu, Renaud; Wolff, Eleonore (MDPI Publishing, 2016-09-16)
    Separation of savanna land cover components is challenging due to the high heterogeneity of this landscape and spectral similarity of compositionally different vegetation types. In this study, we tested the usability of ...