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The pyrogeography of sub-Saharan Africa: a study of the spatial non-stationarity of fire–environment relationships using GWR

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 incidence. 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 variability 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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Acknowledgments

We would like to thank to Chris Brunsdon who kindly gave his advice on some of the questions related with GWR methodology. Stewart Fotheringham and Martin Charlton research presented in this paper was funded by a Strategic Research Cluster grant (07/SRC/l1168) by Science Foundation Ireland under the National Development Plan. The authors gratefully acknowledge this support.

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Correspondence to Ana C. L. Sá.

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Sá, A.C.L., Pereira, J.M.C., Charlton, M.E. et al. The pyrogeography of sub-Saharan Africa: a study of the spatial non-stationarity of fire–environment relationships using GWR. J Geogr Syst 13, 227–248 (2011). https://doi.org/10.1007/s10109-010-0123-7

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  • DOI: https://doi.org/10.1007/s10109-010-0123-7

Keywords

  • Africa
  • Burned areas
  • GWR
  • OLS
  • Spatial non-stationarity

JEL Classification

  • C12
  • C13
  • C21