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University of the Witwatersrand (1998)

Fuel load estimation in Savanna ecosystems in Mozambique

Mangue PD

Titre : Fuel load estimation in Savanna ecosystems in Mozambique

Auteur : Mangue PD

Université de soutenance : University of the Witwatersrand

Grade : Master of Science (MS) 1998

Empirical models for five fuel load categories, namely standing live and dead grass and forbs, tree and grass litter on the ground, twigs (<1 cm diameter), large-diameter dead woody (twigs > 1 cm diameter) and shrubs were developed using multiple regression analysis. Thirty-five data sites out of fifty from Mozambique (10), Zambia (10), Zimbabwe (10) and, South Africa (20) were used for construction of the models and the remaining data were used for validation. The models developed, although empirical, do suggest which aspects of the underlying biology are important in controlling fuel loads. Standing grass fuels, litter and twigs fuels are all predicable, with coefficients of determination of between 15 and 48%, from annual rainfall and tree basal area. The data in Mozambique were collected in two different edaphic-climatic regions ; one in moist/dystrophic savanna in August/1996 at Sussundenga and other in dry/eutrophic savanna in September/1996 at Mabalane. Standing live and dead grass and forbs, tree and grass leaf litter on the ground and twigs (1 < cm diameter) at 10 m intervals were sampled using one 100 m transect. Measurements were made also for large-diameter dead woody fuel, tree and shrub basal area, canopy cover and shrub volume. The data from other southern African sites were collected in 1994, 1995 and 1996, during the dry season using the same method. Litter and twigs constituted a large component of fuel load in Mabalane, representing 52 and 37% respectively, whilst in Sussundenga, grass, litter and twigs were evenly distributed. The total above ground fuel load in moist/dystrophic savanna (Sussundenga) was greater (690 g/m2) than that from arid/eutrop’hic savanna (470 g/m2). The models were extrapolated to the entire surface area of Mozambique. The calculated total aboveground fuel load estimated for Mozambique was 397.2 million tons. If all this fuel burned once every three years, the output of trace gases would be 40 Tg/yr of C02, 59 Gg/yr of CH4,1.6 Tg/yr of CO, 76 Gg/yr of NOx and 3.7 Gg/yr of N20.

Présentation (NRF)

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