{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,4]],"date-time":"2025-11-04T23:21:16Z","timestamp":1762298476038,"version":"build-2065373602"},"reference-count":46,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2016,8,17]],"date-time":"2016-08-17T00:00:00Z","timestamp":1471392000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>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 within them. Baseline maps of woody resources are important for analyzing change over time. Freely available, and highly repetitive, C-band data has the potential to be a viable alternative to high-resolution commercial SAR imagery (e.g., RADARSAT-2, ALOS2) in generating large-scale woody resources maps. Using airborne LiDAR as calibration, we investigated the relationships between hyper-temporal C-band ASAR data and woody structural parameters, namely total canopy cover (TCC) and total canopy volume (TCV), in a deciduous savanna environment. Results showed that: the temporal filter reduced image variance; the random forest model out-performed the linear model; while the TCV metric consistently showed marginally higher accuracies than the TCC metric. Combinations of between 6 and 10 images could produce results comparable to high resolution commercial (C- &amp; L-band) SAR imagery. The approach showed promise for producing a regional scale, locally calibrated, baseline maps for the management of deciduous savanna resources, and lay a foundation for monitoring using time series of data from newer C-band SAR sensors (e.g., Sentinel1).<\/jats:p>","DOI":"10.3390\/rs8080661","type":"journal-article","created":{"date-parts":[[2016,8,17]],"date-time":"2016-08-17T10:23:21Z","timestamp":1471429401000},"page":"661","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Hyper-Temporal C-Band SAR for Baseline Woody Structural Assessments in Deciduous Savannas"],"prefix":"10.3390","volume":"8","author":[{"given":"Russell","family":"Main","sequence":"first","affiliation":[{"name":"Ecosystems Earth Observation, Natural Resources and the Environment, CSIR, Pretoria 0001, South Africa"},{"name":"Department of Geography, Geomatics and Meteorology, University of Pretoria, Pretoria 0028, South Africa"}]},{"given":"Renaud","family":"Mathieu","sequence":"additional","affiliation":[{"name":"Ecosystems Earth Observation, Natural Resources and the Environment, CSIR, Pretoria 0001, South Africa"},{"name":"Department of Geography, Geomatics and Meteorology, University of Pretoria, Pretoria 0028, South Africa"}]},{"given":"Waldo","family":"Kleynhans","sequence":"additional","affiliation":[{"name":"Remote Sensing Research Unit, Meraka Institute, CSIR, Pretoria 0001, South Africa"},{"name":"Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Pretoria 0001, South Africa"}]},{"given":"Konrad","family":"Wessels","sequence":"additional","affiliation":[{"name":"Department of Geography, Geomatics and Meteorology, University of Pretoria, Pretoria 0028, South Africa"},{"name":"Remote Sensing Research Unit, Meraka Institute, CSIR, Pretoria 0001, South Africa"}]},{"given":"Laven","family":"Naidoo","sequence":"additional","affiliation":[{"name":"Ecosystems Earth Observation, Natural Resources and the Environment, CSIR, Pretoria 0001, South Africa"},{"name":"Department of Geography, Geomatics and Meteorology, University of Pretoria, Pretoria 0028, South Africa"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7893-6421","authenticated-orcid":false,"given":"Gregory","family":"Asner","sequence":"additional","affiliation":[{"name":"Department of Global Ecology, Carnegie Institution for Science, Stanford, CA 94305, USA"}]}],"member":"1968","published-online":{"date-parts":[[2016,8,17]]},"reference":[{"key":"ref_1","first-page":"517","article-title":"Tree-grass interactions in savannas","volume":"28","author":"Scholes","year":"2013","journal-title":"Ecology"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"846","DOI":"10.1038\/nature04070","article-title":"Determinants of woody cover in African savannas","volume":"438","author":"Sankaran","year":"2005","journal-title":"Nature"},{"key":"ref_3","first-page":"467","article-title":"Consumption and direct-use values of savanna bio-resources used by rural households in Mametja, a semiarid area of Limpopo province, South Africa","volume":"99","author":"Twine","year":"2003","journal-title":"S. Afr. J. Sci."},{"key":"ref_4","first-page":"658","article-title":"The importance of non-timber forest products in rural livelihood security and as safety nets: A review of evidence from South Africa","volume":"100","author":"Shackleton","year":"2004","journal-title":"S. Afr. J. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"381","DOI":"10.5194\/bg-11-381-2014","article-title":"A full greenhouse gases budget of Africa: Synthesis, uncertainties, and vulnerabilities","volume":"11","author":"Valentini","year":"2014","journal-title":"Biogeosciences"},{"key":"ref_6","first-page":"1","article-title":"A tale of two villages: Assessing the dynamics of fuelwood supply in communal landscapes in South Africa","volume":"40","author":"Matsika","year":"2012","journal-title":"Environ. Conserv."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1111\/j.1365-2028.2008.01051.x","article-title":"Bush encroachment under three contrasting land-use practices in a mesic South African savanna","volume":"47","author":"Wigley","year":"2009","journal-title":"Afr. J. Ecol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"615","DOI":"10.1111\/j.1365-2486.2007.01512.x","article-title":"Shrub encroachment in North American grasslands: Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs","volume":"14","author":"Knapp","year":"2008","journal-title":"Glob. Chang. Biol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1217","DOI":"10.1080\/01431160110092867","article-title":"Savanna and tropical rainforest biomass estimation and spatialization using JERS-1 data","volume":"23","author":"Santos","year":"2002","journal-title":"Int. J. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2861","DOI":"10.1016\/j.rse.2010.02.022","article-title":"Measuring biomass changes due to woody encroachment and deforestation\/degradation in a forest\u2013savanna boundary region of central Africa using multi-temporal L-band radar backscatter","volume":"115","author":"Mitchard","year":"2011","journal-title":"Remote Sens. Environ."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"412","DOI":"10.1109\/36.134090","article-title":"Dependance of radar backscatter on coniferous forest biomass","volume":"30","author":"Dobson","year":"1992","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1109\/36.134089","article-title":"Relating forest biomass to SAR data","volume":"30","author":"Beaudoin","year":"1992","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"179","DOI":"10.5194\/bg-9-179-2012","article-title":"Mapping tropical forest biomass with radar and spaceborne LiDAR in Lop\u00e9 National Park, Gabon: Overcoming problems of high biomass and persistent cloud","volume":"9","author":"Mitchard","year":"2012","journal-title":"Biogeosciences"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1016\/j.rse.2005.10.019","article-title":"Empirical relationships between AIRSAR backscatter and LiDAR-derived forest biomass, Queensland, Australia","volume":"100","author":"Lucas","year":"2006","journal-title":"Remote Sens. Environ."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1016\/j.rse.2015.06.013","article-title":"Assessment of the mapping of fractional woody cover in southern African savannas using multi-temporal and polarimetric ALOS PALSAR L-band images","volume":"166","author":"Urbazaev","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"609","DOI":"10.3390\/rs8070609","article-title":"Airborne S-band SAR for forest biophysical retrieval in temperate mixed forests of the UK","volume":"8","author":"Ningthoujam","year":"2016","journal-title":"Remote Sens."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2142","DOI":"10.1109\/TGRS.2004.834633","article-title":"Microwave scattering from mixed-species forests, Queensland, Australia","volume":"42","author":"Lucas","year":"2004","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1219","DOI":"10.1109\/TGRS.2005.846878","article-title":"Multitemporal repeat pass SAR interferometry of boreal forests","volume":"43","author":"Askne","year":"2005","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"758","DOI":"10.1109\/36.499781","article-title":"Seasonal dynamics of C-band backscatter of boreal forests with applications to biomass and soil moisture estimation","volume":"34","author":"Pulliainen","year":"1996","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"234","DOI":"10.1016\/j.isprsjprs.2015.04.007","article-title":"Savannah woody structure modelling and mapping using multi-frequency (X-, C- and L-band) Synthetic Aperture Radar data","volume":"105","author":"Naidoo","year":"2015","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.rse.2013.07.011","article-title":"Toward structural assessment of semi-arid African savannahs and woodlands: The potential of multitemporal polarimetric RADARSAT-2 fine beam images","volume":"138","author":"Mathieu","year":"2013","journal-title":"Remote Sens. Environ."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1555","DOI":"10.1080\/01431160903475258","article-title":"Application of multi-temporal ENVISAT ASAR data to agricultural area mapping in the Pearl River Delta","volume":"31","author":"Wang","year":"2010","journal-title":"Int. J. Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"490","DOI":"10.1016\/j.rse.2010.09.018","article-title":"Retrieval of growing stock volume in boreal forest using hyper-temporal series of ENVISAT ASAR ScanSAR backscatter measurements","volume":"115","author":"Santoro","year":"2011","journal-title":"Remote Sens. Environ."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"927","DOI":"10.1109\/36.752211","article-title":"Multitemporal behavior of L- and C-band SAR observations of boreal forests","volume":"37","author":"Pulliainen","year":"1999","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1109\/36.551931","article-title":"C-band repeat-pass interferometric SAR observations of the forest","volume":"35","author":"Askne","year":"1997","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_26","unstructured":"Santoro, M., Schmullius, C., Pathe, C., Schwilk, J., Beer, C., Thurner, M., Fransson, J.E.S., Shvidenko, A., Schepaschenko, D., and McCallum, I. (2013, January 9\u201313). Estimates of forest growing stock volume of the northern hemisphere from ENVISAT ASAR. Proceedings of ESA Living Planet Symposium, Edinburgh, UK."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"288","DOI":"10.1016\/S0034-4257(01)00280-2","article-title":"Estimating forest structure in wetlands using multitemporal SAR","volume":"79","author":"Townsend","year":"2002","journal-title":"Remote Sens. Environ."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1117\/1.JRS.6.063588","article-title":"Aboveground biomass estimation of tropical forest from Envisat advanced synthetic aperture radar data using modeling approach","volume":"6","author":"Kumar","year":"2012","journal-title":"J. Appl. Remote Sens."},{"key":"ref_29","unstructured":"Mucina, L., and Rutherford, M.C. (2006). The Vegetation of South Africa, Lesotho and Swaziland, South African National Biodiversity Institute."},{"key":"ref_30","unstructured":"Du Toit, J., Biggs, H., and Rogers, K.H. (2003). The Kruger Experience: Ecology and Management of Savanna Heterogeneity, London Island Press."},{"key":"ref_31","unstructured":"GAMMA (2008). GAMMA: Geocoding and Image Registration Documentation: User\u2019s Guide, GAMMA."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2373","DOI":"10.1109\/36.964973","article-title":"Filtering of multichannel SAR images","volume":"39","author":"Quegan","year":"2001","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_33","first-page":"1559","article-title":"A comprehensive evaluation of filters for radar speckle suppression","volume":"3","author":"Sheng","year":"1996","journal-title":"Int. Geosci. Remote Sens. Symp."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"244","DOI":"10.2747\/1548-1603.41.3.244","article-title":"Speckle noise reduction in SAR imagery using a local adaptive median filter","volume":"41","author":"Qiu","year":"2004","journal-title":"GISci. Remote Sens."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1117\/1.2794018","article-title":"Carnegie Airborne Observatory: In-flight fusion of hyperspectral imaging and waveform light detection and ranging for three-dimensional studies of ecosystems","volume":"1","author":"Asner","year":"2007","journal-title":"J. Appl. Remote Sens."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1016\/j.foreco.2010.09.012","article-title":"Impact of communal land use and conservation on woody vegetation structure in the Lowveld savannas of South Africa","volume":"261","author":"Wessels","year":"2011","journal-title":"For. Ecol. Manag."},{"key":"ref_37","unstructured":"Henderson, F.M., and Lewis, A.J. (1996). Principles & Applications of Imaging Radar. Manual of Remote Sensing, John Wiley and Sons."},{"key":"ref_38","unstructured":"SAWS (2015). South African Weather Service Rainfall Data 2006 to 2010, South African Weather Service."},{"key":"ref_39","unstructured":"SANParks (2015). South African National Parks Rainfall Data 2006 to 2010, South African National Parks."},{"key":"ref_40","unstructured":"R Development Core Team (2016). R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing."},{"key":"ref_41","unstructured":"du Toit, J.T., Biggs, H.C., and Rogers, K.H. (2003). The Kruger Experience: Ecology and Management of Savanna Heterogeneity, Island Press."},{"key":"ref_42","unstructured":"Breiman, L., Friedman, J., Stone, C.J., and Olshen, R.A. (1984). Classification and Regression Trees, Taylor & Francis."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Naidoo, L., Mathieu, R., Main, R., Kleynhans, W., Wessels, K., Asner, G.P., and Leblon, B. (2014). The assessment of data mining algorithms for modelling Savannah Woody cover using multi-frequency (X-, C- and L-band) synthetic aperture radar (SAR) datasets. IEEE Geosci. Remote Sens. Symp.","DOI":"10.1109\/IGARSS.2014.6946608"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1088\/1748-9326\/8\/1\/014007","article-title":"Unsustainable fuelwood extraction from South African savannas","volume":"8","author":"Wessels","year":"2013","journal-title":"Environ. Res. Lett."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"627","DOI":"10.1109\/36.135825","article-title":"Radar modeling of a boreal forest","volume":"29","author":"Chauhan","year":"1991","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_46","unstructured":"Bucini, G., Hanan, N.P., Boone, R.B., Smit, I.P.J., Saatchi, S.S., Lefsky, M.A., and Asner, G.P. (2010). Ecosystem Function in Savannas, CRC Press."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/8\/8\/661\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:28:34Z","timestamp":1760210914000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/8\/8\/661"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,8,17]]},"references-count":46,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2016,8]]}},"alternative-id":["rs8080661"],"URL":"https:\/\/doi.org\/10.3390\/rs8080661","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2016,8,17]]}}}