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Browsing by Author "Main, Russell S"

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Aboveground biomass density models for NASA’s Global Ecosystem Dynamics Investigation (GEDI) lidar mission

Author: Duncanson, L ; Kellner, JR ; Armston, J ; Dubayah, R ; Minora, DM ; Hancock, S ; Healey, SP ; Patterson, PL ; Main, Russell S ; Naidoo, Laven Date: Mar 2022 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 paper presents the development ... Read more
Comparison between sensors with different spectral resolutions, relative to the sumbandila satellite, for assessing site quality differences, in eucalyptus grandis plantations

Author: Main, Russell S ; Cho, Moses A ; Van Aardt, J ; Majeke, B Date: Oct 2008 The majority of earth observation studies have for years made use of data from multispectral spaceborne sensors. More recently though, both airborne and spaceborne narrowband hyperspectral sensors have come to the fore and are able to provide ... Read more
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

Author: Mathieu, Renaud ; Main, Russell S ; Roy, DP ; Naidoo, Laven ; Yang, H Date: Jun 2019 Savannahs are mixed woody-grass communities where low-intensity surface fires are common, affecting mostly the grass layer and rarely damaging trees. We investigated the effect of surface fires in a savannah system in the Kruger National Park, ... Read more
Estimating South African maize biomass using integrated high-resolution UAV and sentinel 1 and 2 datasets

Author: Naidoo, Laven ; Main, Russell S ; Cho, Moses A ; Madonsela, Sabelo ; Majozi, Nobuhle, P Date: Jul 2021 Sentinel-1 and Sentinel-2 have provided consistent hyper-temporal information (5–7 days or earlier) at high spatial resolutions (10m) on biophysical composition, structural and physiological conditions of crops in a variety of environments. ... Read more
Evaluating variations of physiology-based hyperspectral features along a soil water gradient in Eucalyptus grandis plantation

Author: Cho, Moses A ; van Aardt, J ; Main, Russell S ; Majeke, B Date: Apr 2010 Remote sensing is viewed as a cost-effective alternative to intensive field surveys in assessing site factors that affect growth of Eucalyptus grandis over broad areas. The objective of this study was to assess the utility of hyperspectral ... Read more
Exploring the utility of Sentinel-2 for estimating maize chlorophyll content and leaf area index across different growth stages

Author: Madonsela, Sabelo ; Cho, Moses A ; Naidoo, Laven ; Main, Russell S ; Majozi, Nobuhle P Date: Dec 2021 This study investigated the utility of Sentinel-2 spectral data for estimating leaf area index (LAI), leaf and canopy chlorophyll content of maize at different growth stages. Vegetation indices based on the visible-near infrared and red-edge ... Read more
Hyper-temporal c-band SAR for baseline woody structural assessments in deciduous savannas

Author: Main, Russell S ; Mathieu, Renaud SA ; Kleynhans, W ; Wessels, Konrad J ; Naidoo, Laven ; Asner, GP Date: Aug 2016 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 and manage change ... Read more
Impact of communal land use and conservation on woody vegetation structure in the Lowveld savannas of South Africa

Author: Wessels, Konrad J ; Mathieu, Renaud SA ; Erasmus, BFN ; Asner, GP ; Smit, IPJ ; Van Aardt, JAN ; Main, Russell S ; Fisher, J ; Marais, W ; Kennedy-Bowdoin, T ; Knapp, DE ; Emerson, R ; Jacobson, J Date: Jan 2011 Millions of people rely on savannas for ecosystem services, such as the provision of grazing and fuel wood, so it is important to determine the extent to which utilization affects woody vegetation resources. Using airborne LiDAR from the ... Read more
Impact of communal land use and conservation on woody vegetation structure in the Lowveld savannas of South Africa – Lidar results

Author: Wessels, Konrad J ; Mathieu, Renaud SA ; Erasmus, BFN ; Asner, GP ; Smit, IPJ ; Van Aardt, JAN ; Main, Russell S ; Fisher, J Date: Apr 2011 People in the rural, communal areas of South Africa rely on live fuel wood for more than 90% of their energy requirements. Using airborne lidar from the Carnegie Airborne Observatory (CAO) the authors compared tree canopy cover and height ... Read more
Indirect estimation of structural parameters in South African forests using MISR-HR and LiDAR remote sensing data

Author: Mahlangu, Precious N ; Mathieu, Renaud SA ; Wessels, Konrad J ; Naidoo, Laven ; Verstraete, M ; Asner, G ; Main, Russell S Date: Sep 2018 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 observing the land surface ... Read more
Integrating remote sensing and ancillary data for regional ecosystem assessment: eucalyptus grandis agro-system in kwazulu-Natal, South Africa

Author: Cho, Moses A ; Van Aardt, J ; Main, Russell S ; Majeke, B ; Mathieu, Renaud SA ; Norris-Rogers, M ; Du Plessis, M ; Ramoelo, Abel Date: Jul 2009 The study demonstrates that the integration of remote sensing and in situ data could be important in providing more accurate estimates of E. grandis state in KwaZulu Natal, South Africa compared to remote sensing models. Such modelling effort ... Read more
An investigation into robust spectral indices for leaf chlorophyll estimation

Author: Main, Russell S ; Cho, Moses A ; Mathieu, Renaud SA ; O'Kennedy, Maretha M ; Ramoelo, Abel ; Koch, S Date: Nov 2011 Quantifying photosynthetic activity at the regional scale can provide important information to resource managers, planners and global ecosystem modelling efforts. With increasing availability of both hyperspectral and narrow band multispectral ... Read more
Machine learning modelling of crop structure within the Maize Triangle of South Africa

Author: Naidoo, Laven ; Main, Russell S ; Cho, Moses A ; Madonsela, Sabelo ; Majozi, Nobuhle, P Date: Jan 2022 Maize has been identified as a strategic commodity for the reduction of poverty and enhancement of food security in the African continent. Climate variability and difficult economic conditions are pressuring farmers to produce higher (maize) ... Read more
Mapping and monitoring fractional woody vegetation cover in the arid savannas of Namibia using LiDAR training data, machine learning and ALOS PALSAR data

Author: Wessels, Konrad J ; Mathieu, Renaud ; Knox, N ; Main, Russell S ; Naidoo, Laven ; Steenkamp, Karen C Date: Nov 2019 Namibia is a very arid country, but experienced significant bush encroachment which has decreased ivestock productivity. Therefore, it is essential to monitor bush encroachment and widespread debushing activities. The aim of study was to ... Read more
Mapping big tree presence in open savanna, using tree shadow and high resolution multispectral imagery

Author: Main, Russell S ; Cho, Moses A ; Mathieu, Renaud SA ; Asner, G Date: Oct 2012 Large scattered trees play an important role in the functioning of savanna landscapes. They act as focal points for various organism activities, which influence the distribution of nutrients and water within the landscape, which in turn ... Read more
A radar and LiDAR-based earth observation system for monitoring savanna woody structure in southern Africa

Author: Mathieu, Renaud ; Wessels, Konrad ; Main, Russell S ; Naidoo, Laven ; Van der Bergh, Frans ; Erasmus, Barend Date: Apr 2018 In southern Africa, landscapes are dominated by savannas, i.e., mixed tree-grass communities. These savannas are threatened by land clearing and degradation, as well as the densification of woody plants, a process known as bush encroachment. ... Read more
Savannah woody structure modelling and mapping using multifrequency (X-, C- and L-band) synthetic aperture radar data

Author: Naidoo, Laven ; Mathieu, Renaud SA ; Main, Russell S ; Kleynhans, W ; Wessels, Konrad J ; Asner, G ; Leblon, B Date: Jul 2015 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 in South Africa (80% ... Read more
Spectral variability within species and its effects on savanna tree species discrimination

Author: Cho, Moses A ; Debba, Pravesh ; Mathieu, Renaud SA ; Van Aardt, J ; Asner, G ; Naidoo, Laven ; Main, Russell S Date: Jul 2009 Differences in within-species phenology and structure driven by factors including topography, edaphic properties, and climatic variables present important challenges for species differentiation with remote sensing in the Kruger National Park, ... Read more
Toward structural assessment of semi-arid African savannahs and woodlands: The potential of multitemporal polarimetric RADARSAT-2 fine beam images

Author: Mathieu, Renaud SA ; Naidoo, Laven ; Cho, Moses A ; Leblon, B ; Main, Russell S ; Wessels, Konrad J ; Asner, GP ; Buckley, J ; Van Aardt, J ; Erasmus, BFN ; Smit, IPJ Date: Nov 2013 Woody vegetation structure affects wildlife habitat selection and species diversity for a wide range of taxa, and at a variety of scales. Indicators of woody structure can indicate the spatio-temporal variability of biodiversity, species ... Read more
Tree cover, tree height and bare soil cover differences along a land use degradation gradient in semi-arid savannas, South Africa

Author: Mathieu, Renaud SA ; Wessels, Konrad J ; Asner, G ; Knapp, D ; van Aardt, J ; Main, Russell S ; Cho, Moses A ; Erasmus, B ; Smit, I Date: Jul 2009 High resolution airborne hyperspectral and discrete return LiDAR data were used to assess bare soil and tree cover differences along a land use transect consisting of state-owned, privately-owned conservation areas, and communal areas in South ... Read more

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