We have used remotely sensed fire information for the whole globe and aggregated this information by the WWF ecoregions, to produce an ecologically-based global fire map (figure below ). Using this map we have tested the intermediate fire-productivity model [2,3], i.e. that ﬁre activity changes along the productivity/aridity gradient following a humped relationship. The results suggest that fires occur in all biomes and in nearly all world ecoregions. Fire activity peaked in tropical grasslands and savannas, and signiﬁcantly decreased towards the extremes of the productivity gradient. Both the sensitivity of ﬁre to high temperatures and the above-ground biomass increased monotonically with productivity. In other words, ﬁre activity in low-productivity ecosystems is not driven by warm periods and is limited by low biomass; in contrast, in high-productivity ecosystems ﬁre is more sensitive to high temperatures, and in these ecosystems, the available biomass for ﬁres is high. The results support the intermediate ﬁre–productivity model on a global scale and suggest that climatic warming may affect ﬁre activity differently depending on the productivity of the region. Fire regimes in productive regions are more vulnerable to warming (drought-driven ﬁre regime changes), while in low-productivity regions ﬁre activity is more vulnerable to fuel changes (fuel-driven ﬁre regime changes ).
Figure: An ecologically-based global fire map, from Pausas & Ribeiro (2013) . The shape file is available under request [email here].
 Pausas J.G. & Bradstock R.A. 2007. Fire persistence traits of plants along a productivity and disturbance gradient in Mediterranean shrublands of SE Australia. Global Ecol. & Biogeogr. 330-340. [pdf | doi]