Effect of canopy cover and canopy background variables on spectral profiles of savanna rangeland bush encroachment species based on selected Acacia species (mellifera,tortilis, karroo) and Dichrostachys cinerea at Mokopane,South Africa |
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| Institution: | 1. State Key Laboratory Breeding Base of Marine Genetic Resource, Third Institute of Oceanography, SOA, Xiamen 361005, China;2. Collaborative Innovation Center of Deep Sea Biology, Hangzhou 310058, China;3. Shool of Marine Sciences, Ningbo University, Ningbo 315211, China;1. Cátedra de Diversidad Biológica III, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Avenida Vélez Sarsfield 299, Córdoba, Argentina;2. Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET–Universidad Nacional de Córdoba), Avenida Vélez Sarsfield 1611–X5016GCA, 5000 Córdoba, Argentina;3. Mlyňany Arboretum, Institute of Forest Ecology, Slovak Academy of Sciences, Vieska nad Žitavou 178, 95152 Slepčany, Slovakia;1. School of Life Sciences, University of KwaZulu-Natal, P. Bag X01, Scottsville 3209, South Africa;2. Institute of Ecology, Friedrich-Schiller-Universität, Dornburgstr 159, 07743 Jena, Germany;3. Grootfontein Agricultural Development Institute, Private Bag X529, Middelburg, Eastern Cape, South Africa;5. Geosciences Department and Four Corners Water Center, Fort Lewis College, Durango, CO 81301, USA |
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| Abstract: | The proliferation of woody plant species on savanna rangelands (i.e. bush encroachment) degrades rangeland quality, thereby threatening the biodiversity conservation effort as well as pastoral farming. Hyperspectral remote sensing offers possibilities for discriminating encroaching bush species in support of management of semi-arid savanna rangelands. As a preliminary step towards establishing a spectral library of common encroaching species on savanna rangelands, the effect of canopy leaf cover, background dry soil and grass on the spectral profiles of the common encroaching species Acacia karroo, Acacia mellifera, Acacia tortilis and Dichrostachys cinerea was analysed. A sample of healthy mature plants in prime, full leaf condition was utilised at an encroached rangeland in Mokopane, South Africa. The spectral signatures were collected in-situ, using a field spectrometer pointed above the sample specimen canopies. The canopy and canopy background variables tended to modify the reflectance of the encroaching bush species in the near infrared (800–1300 nm) in which they were spectrally most separable. Canopy background dry grass tended to increase near infrared reflectance, while dry soil tended to reduce the spectral contrast among the species. These effects were reduced by high leaf content. In a thicket canopy structure, the overall reflectance tended towards the spectral profile of the more dominant species. |
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| Keywords: | Bush encroachment Hyperspectral remote sensing Rangeland monitoring Savanna rangelands |
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