Abstract
Despite important recent advances in modeling current and future global fire activity in relation to biophysical predictors there remain important uncertainties about finer‐scale spatial heterogeneity of fire and especially about human influences which are typically assessed at coarse‐spatial resolutions. The purpose of the current study is to quantify the influence of biophysical and anthropogenic variables on the spatial distribution of wildfire activity between 1984 and 2010 over an extensive southern Patagonian‐Andean region from ca. 43° to 53° S extending from coastal rainforests to xeric woodland and steppe.We used satellite imagery to map all detectable fires >5 ha from 1984 to 2010 in four study areas (each of 13,100 to 36,635 km2) and field checked 65 of these burns for accuracy of burned vegetation class and fire perimeters. Then, we used the MaxEnt modeling technique to assess the relationships of wildfire distributions to biophysical and human environmental variables in each of the four regions. The 232 fires >5 ha mapped in the four study areas accounted for an area of 1,314 km2indicating that at least 1.8% of the total area burned between 1984 and 2010. In general, areas with intermediate productivity levels (e.g., shrublands) have higher fire probability compared with areas of low and high productivity levels, such as steppe and wet forests, respectively. There is a marked contrast in the flammability of broad vegetation classes in determining fire activity at a regional scale, as well as a strong spatial relationship of wildfires to anthropogenic variables. The juxtaposition of fire‐resistant tall forests with fire‐prone shrublands and woodlands creates the potential for positive feedbacks from human‐set fires to gradually increase the flammability of extensive landscapes through repeated burning. Distance to roads and settlements were also strong predictors, suggesting that fire in all regions is ignition‐limited. However, these anthropogenic predictors influenced probability of fire differently among study regions depending on their main land‐use practices and their past and present socioeconomic contexts.
Highlights
There is growing recognition of the importance of changes in global fire activity as a consequence of climate change as well as an agent of land cover change with potential positive feedbacks of additional greenhouse gases into the atmosphere (Bowman et al 2009)
For an area of ca. 100,000 km2 in southwestern South America we develop a spatially explicit fine-scale resolution record of wildfires from 1984 to 2010 with Landsat satellite imagery (30-m spatial resolution) to examine spatial relationships of fire activity to biophysical and human explanatory variables
We evaluated the biophysical and human ‘‘environmental space’’ of wildfire in this Patagonian region to determine which predictor variables best explains the spatial distribution of wildfire activity during the study period
Summary
There is growing recognition of the importance of changes in global fire activity as a consequence of climate change as well as an agent of land cover change with potential positive feedbacks of additional greenhouse gases into the atmosphere (Bowman et al 2009). Global scale analyses do not effectively incorporate anthropogenic factors that may affect ignition frequency, fire suppression and other land use effects on fire activity (Moritz et al 2012). An improved understanding integrating both biophysical and human drivers of fire activity requires analyses over large areas of biophysical and socioeconomic heterogeneity but at a finescale spatial resolution (;1 km2) and over multidecadal time periods. To date such studies exist only for parts of North America (e.g., Parisien et al 2012) where spatially explicit records of fire activity over the past several decades are available from government-sponsored databases. For an area of ca. 100,000 km in southwestern South America we develop a spatially explicit fine-scale resolution record of wildfires from 1984 to 2010 with Landsat satellite imagery (30-m spatial resolution) to examine spatial relationships of fire activity to biophysical and human explanatory variables
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