Browsing Research articles (Dept of Environmental Science) by Author "Moleele, N."
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Moleele, N.; Ringrose, S.; Arnberg, W.; Lunden, B.; Vanderpost, C. (Taylor and Francis http://www.clas.ufl.edu/lueci/southworth/RS-class-advanced/Discussion-readings/Moleele%20et%20al%202001%20Assessment%20of%20veg%20indexes%20i.pdf, NaN, 2001)[more][less]
Abstract: Considerable signi® cance is placed on the mapping and monitoring of degraded areas in semi-arid regions of the world, including Botswana. Degraded areas include those suVering from bush encroachment, believed to result from heavy cattle grazing over a number of years. However, certain bush encroachment species have been found to be relatively nutrient-rich.The present work considers the extent to which a series of quanti® ed layers throughmainly bush encroachment canopies can be identi® ed using conventional and newly derived vegetation indexes and transforms based on Thematic Mapper (TM) imagery. Field work involved the strati® cation of green biomass into ® rstly the herbaceous cover layer; secondly the 0.3± 1.5m browse layer; then the 1.5± 2.5m browse layer; and ® nally the >2.5m browse layer. Biomass measurements from these layers were statistically associated with conventional vegetation indexes and transforms such as the NormalizedDiVerenceVegetation Index (NDVI), brightness and greenness values, and relatively newly derived darkening indexes involving the mid-infrared bands. When green biomass and transformed pixel data were averaged per classi® ed vegetation unit, weak negative correlations emerged between grass biomass and the transformed pixel data and no signi® cant correlations developed with the woody biomass (browse) layers. However, when point data were used in the analyses, results showed that most indexes and the brightness transform were signi® cantly correlated with the lower browse layer. Only the darkening indexes and brightness function were sensitive to the browse layers individually and the browse plus grass layers. This work shows the limitations of conventional indexes such as the NDVI in terms of browse and herbaceous layer assessment. New indexes for forage assessment based on relationships between the mid-infrared bands, such as those found in the new MODIS TERRA platform, are urgently required for semi-arid areas. URI: http://hdl.handle.net/10311/410 Files in this item: 1
Moleele_IJRS_2001.pdf (903.7Kb) -
Shaikh, M.; Moleele, N.; Ekosse, G.I.E.; Totolo, O.; Atlhopheng, J. (JASEM http://www.ajol.info/index.php/jasem/article/view/43693/27216, June NaN, 2006)[more][less]
Abstract: Since 1988 Botswana has been experiencing an unprecedented increase in vehicular traffic which is suspected to be having contamination effects on soils along heavily used roads in the country. This study aimed at understanding the contamination trends of heavy metals on soils due to vehicular emissions. The soil physicochemistry (bulk density, particle size distribution, pH, electrical conductivity and cation exchange capacity), mineralogy (using x-ray diffraction techniques) and heavy metals (Cd, Pb, Cu and Zn) concentrations were determined for soil samples obtained along the roadside at 2m, 4m, 6m and 100 m of the Gaborone – Tlokweng Emigration/Immigration Boarder Post Road, which is one of the busiest in the country. Bulk density of soil samples were from 1.19 to 1.4; and sand, loamy sand and sandy loam textural classes constituted the soil samples. The soil pH was from 5.09 to 8.57; the EC ranged from 6.27 μS cm-1to 20.3 27 μS cm-1 and the CEC values were from 10.2 meq100g-1 to 27.2 meq100g-1. Clay minerals were identified in the samples as well as feldspar and quartz. The concentration levels for Pb were from 0 mgkg-1 to 71 mgkg-1; Zn were from 5.23 mgkg-1 to 51.26 mgkg-1 ; Cu were from 0.3 mgkg-1 to 18.1 mgkg-1 and Cd 0 mgkg-1 to 2.4 mgkg-1 . The interplay of soil physico-chemistry and mineralogy on heavy metals concentrations is discussed. Although levels of heavy metals concentrations fell below normal ranges, the values obtained were generally higher than those from some developed and developing countries. URI: http://hdl.handle.net/10311/361 Files in this item: 1
Shaikh_JASEM_2006.pdf (1.018Mb)
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