Drought and Spatiotemporal Variability of Forest Fires Across Mexico

Abstract

Understanding the spatiotemporal links between drought and forest fire occurrence is crucial for improving decision-making in fire management under current and future climatic conditions. We quantified forest fire activity in Mexico using georeferenced fire records for the period of 2005-2015 and examined its spatial and temporal relationships with a multiscalar drought index, the Standardized Precipitation-Evapotranspiration Index (SPEI). A total of 47 975 fire counts were recorded in the 11-year long study period, with the peak in fire frequency occurring in 2011. We identified four fire clusters, i.e., regions where there is a high density of fire records in Mexico using the Getis-Ord G spatial statistic. Then, we examined fire frequency data in the clustered regions and assessed how fire activity related to the SPEI for the entire study period and also for the year 2011. Associations between the SPEI and fire frequency varied across Mexico and fire-SPEI relationships also varied across the months of major fire occurrence and related SPEI temporal scales. In particular, in the two fire clusters located in northern Mexico (Chihuahua, northern Baja California), drier conditions over the previous 5 months triggered fire occurrence. In contrast, we did not observe a significant relationship between drought severity and fire frequency in the central Mexico cluster, which exhibited the highest fire frequency. We also found moderate fire-drought associations in the cluster situated in the tropical southern Chiapas where agriculture activities are the main causes of forest fire occurrence. These results are useful for improving our understanding of the spatiotemporal patterns of fire occurrence as related to drought severity in megadiverse countries hosting many forest types as Mexico.

Dendrochronological reconstruction of fire history in coniferous forests in the Monarch Butterfly Biosphere Reserve, Mexico

“…In this region, 78% of rainfall occurs from July to October, which means that, during the rest of the year, fuels could reach the conditions that allow fire spread (McKenzie 2004). Previous research has found no relationship between severity of droughts and fire frequency in central Mexico (Pompa-García et al 2017), which is consistent with our findings. It confirms that fires in the MBBR occur when rainfall is just below the annual average, and their incidence is not strongly related to severe drought and ENSO fluctuations.…”

“…Although the biogeographic aspect can be a determining factor in fire regimes in tropical coniferous forests, it has also been suggested that fire regimes in these ecosystems are mostly associated with human activity, given the long history of management that these forests have experienced (Myers and Rodríguez-Trejo 2009;Pompa-García et al 2017). The MBBR is not an exception, since it has been an important timber supply area for central Mexico since the twentieth century, especially for forestry and mining industries (Ibarra-García 2011), including fir forests, currently protected for the monarch butterfly migration.…”

Developing Models to Predict the Number of Fire Hotspots from an Accumulated Fuel Dryness Index by Vegetation Type and Region in Mexico

“…Given the well-documented variations in fire regimes seasonality in the country (e.g., [62][63][64][65]), five geographical regions were established: Northwest (NW), Northeast (NE), North-Centre (NC), Centre (C), and South (S) ( Figure 1). The definition of regions was based on the North American Level 3 Ecoregions Map (EPA, https://www.epa.gov/ecoresearch/ecoregions-north-america), together with previous analysis of the temporal trends and spatial patterns of clustering in fire hotspots in the country [54,60,61]. Vegetation types were reclassified into the following categories: temperate forest (FOR), dry tropical forest (DTROPF), seasonally dry tropical forest (SDTROPF), seasonally wet tropical forest (SWTROPF), wet tropical forest (WTROPF), wetlands (WET), desert shrubby vegetation (DSHR), natural pastureland (NPAS), and agricultural croplands (AGR) ( Figure 1).…”

“…Some studies have evaluated the role of weather variables such as precipitation or temperature on fire occurrence risk (e.g., [51][52][53]), mainly at regional or local scales. The work of Pompa-Garcia et al [54] explored the association between fire records and the Standardized Precipitation-Evapotranspiration Index (SPEI) drought index, finding that the relationships of drought and fire vary by regions in the country. The FPI system [28] was tested by Sepulveda et al [55,56] in the region of Baja California, but its performance has not been tested nationally for fire occurrence prediction.…”

Variability and Factors of Influence of Extreme Wet and Dry Events in Northern Mexico

“…According to [4], Mexico has historically been affected by a number of extreme events of both types as well as by fires associated with extreme dry events; most notably in the states of Chihuahua, Coahuila, Durango, Chiapas, Mexico City, Tabasco, Baja California Sur, Baja California, Sonora and Sinaloa [5][6][7]. In the northern states of Mexico (Chihuahua, Baja California, Durango, Baja California Sur, Sinaloa and Sonora), summer precipitation (June-September) represents around 60% of total annual precipitation; however, in recent decades, significant meteorological irregularities have been recorded in various different climatic classifications [8][9][10] which predict that Mexico will become dryer as a consequence of global warming and that this drying may already be underway [11].…”