Relationships between Human Population Density and Burned Area at Continental and Global Scales

Abstract

We explore the large spatial variation in the relationship between population density and burned area, using continental-scale Geographically Weighted Regression (GWR) based on 13 years of satellite-derived burned area maps from the global fire emissions database (GFED) and the human population density from the gridded population of the world (GPW 2005). Significant relationships are observed over 51.5% of the global land area, and the area affected varies from continent to continent: population density has a significant impact on fire over most of Asia and Africa but is important in explaining fire over < 22% of Europe and Australia. Increasing population density is associated with both increased and decreased in fire. The nature of the relationship depends on land-use: increasing population density is associated with increased burned are in rangelands but with decreased burned area in croplands. Overall, the relationship between population density and burned area is non-monotonic: burned area initially increases with population density and then decreases when population density exceeds a threshold. These thresholds vary regionally. Our study contributes to improved understanding of how human activities relate to burned area, and should contribute to a better estimate of atmospheric emissions from biomass burning.

Causal relationships versus emergent patterns in the global controls of fire frequency

“…A number of analytical studies of both regional and global data sets have shown a unimodal relationship between burnt area and human population density, when log-transformed to emphasise the form of the relationship at very low population densities (Archibald et al, 2009;Aldersley et al, 2011;Bistinas et al, 2013). We also predict this unimodal response, even though the underlying fitted relationship is monotonically decreasing.…”

“…Possible mechanisms include the removal of wood for heating and cooking, roads and clearings creating barriers to fire spread, and fragmentation through urbanisation. It is likely that the mechanisms are different at different levels of population density and in different regions (Bistinas et al, 2013;Knorr et al, 2014).…”

Reconstructions of biomass burning from sediment-charcoal records to improve data–model comparisons

“…However, the spatial patterns underlying these trends, and the extent to which finer-scale variations match paleofire evidence are unknown. Moreover, the finding that precipitation is more important than temperature in driving trends in fire activity globally contradicts analyses of paleodata (Daniau et al, 2012;Marlon et al, 2012;Power et al, 2012;Marlon et al, 2013), as well as satellite remote-sensing data (Bistinas et al, 2013), raising key questions about how temperature, precipitation, and their interactions affect variations in global biomass burning. Another fire modeling study (Brücher et al, 2014) compared model output to paleofire data from the GCD at regional scales from the mid-Holocene until the pre-industrial era in the 18th century.…”

Global combustion: the connection between fossil fuel and biomass burning emissions (1997–2010)

“…As demonstrated here, the inverse relationship between fossil fuel and biomass burning is an important phenomenon and should be captured in models of the anthropogenic drivers of global fire. Previous global fire modelling efforts have included human population density, cropland and pasture lands, GDP, road density and compilations of variables captured by the human footprint [15,[17][18][19]25]. This study suggests that incorporation of fossil fuel emissions into global fire models may improve prediction by better representing the shift from open landscape burning to more industrialized forms of combustion.…”