Sa, Ana and Pereira, Jose and Charlton, Martin and Mota, Bernardo and Barbosa, Paulo and Fotheringham, Stewart
(2011)
The pyrogeography of sub-Saharan Africa: a study
of the spatial non-stationarity of fire–environment
relationships using GWR.
Journal of Geographical Systems, 13 (3).
pp. 227-248.
ISSN 1435-5930
Abstract
This study analyses the relationship between fire incidence and some
environmental factors, exploring the spatial non-stationarity of the phenomenon in
sub-Saharan Africa. Geographically weighted regression (GWR) was used to study
the above relationship. Environment covariates comprise land cover, anthropogenic
and climatic variables. GWR was compared to ordinary least squares, and the
hypothesis that GWR represents no improvement over the global model was tested.
Local regression coefficients were mapped, interpreted and related with fire inci-
dence. GWR revealed local patterns in parameter estimates and also reduced the
spatial autocorrelation of model residuals. All the covariates were non-stationary
and in terms of goodness of fit, the model replicates the data very well (
R
2
=
87%).
Vegetation has the most significant relationship with fire incidence, with climate
variables being more important than anthropogenic variables in explaining vari-
ability of the response. Some coefficient estimates exhibit locally different signs,
which would have gone undetected by a global approach. This study provides an
improved understanding of spatial fire–environment relationships and shows that
GWR is a valuable complement to global spatial analysis methods. When studying
fire regimes, effects of spatial non-stationarity need to be incorporated in
vegetation-fire modules to have better estimates of burned areas and to improve
continental estimates of biomass burning and atmospheric emissions derived from
vegetation fires.
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