Precipitation dominates fire occurrence in Greece (1900–2010): its dual role in fuel build-up and dryness

Abstract

Abstract. Historical fire records and meteorological observations spanning over one century were assembled in a database to collect long-term fire and weather data in Greece. Positive/negative events of fire occurrence on an annual basis were considered as the years where the annual values of the examined parameters were above (positive values) or below (negative values) the 95 % confidence limits around the trend line of the corresponding parameter. To analyse the association of positive/negative events of fire occurrence with meteorological extremes, we proceeded with a cross-tabulation analysis based on a Monte Carlo randomization.Positive/negative values of total annual precipitation were randomly associated with the corresponding values of burned areas, and significant associations were observed for seasonal precipitation totals (spring and fire season). Fire season precipitation is the dominant factor coinciding with negative values of area burned, while years with high spring precipitation coincide with years with large areas burned. These results demonstrate the dual role of precipitation in controlling a fire's extent through fuel build-up and dryness. Additionally, there is a clear outperformance of precipitation-related variables compared with temperature-related weather revealing that, at least in Greece, total area burned at the national scale is controlled by precipitation totals rather than air temperature.This analysis improves our understanding of the underlying mechanisms of fire regimes and provides valuable information concerning the development of models relating fire activity to weather parameters, which are essential when facing a changing climate that may be associated with shifts in various aspects of the typical fire regimes of ecosystems. Our results may allow fire managers to more easily incorporate the effect of extreme weather conditions into longterm planning strategies. They contribute to the exploration of fire-climate relationships and may become more important if climate change scenarios are used to predict the occurrence of future extreme weather taking into consideration that climate change is discussed on the basis of changes of extremes rather than changes in means.

The sensitivity of US wildfire occurrence to pre-season soil moisture conditions across ecosystems

“…As soil moisture in this study is used as a proxy for vegetation moisture and general climate conditions, a wet pre-season in certain vegetation types is correlated with more primary production creating increased fuel availability when fire season arrives. This is further corroborated by observations made by Xystrakis et al (2014), which saw high spring precipitation succeeded by high burned area values. The case that would lead to the most fires in these land cover types is likely that of a very wet pre-season, followed by a very dry fire season.…”

“…The first step in algorithm development was to disaggregate the fire data by wildfire size class (table 1). Annual January through April (2003-2014) soil moisture from the GRACE-derived CLSM-DA data were averaged into single two-dimensional maps (latitude × longitude) for each year that depict a fire season's antecedent moisture conditions (Xystrakis et al 2014). Annual total fire occurrence and cumulative burned area maps, aggregated from the rasterized FPA FOD data, were produced for each wildfire class, covering the period ranging May through April of the following year.…”

Interactions between Climate, Land Use and Vegetation Fire Occurrences in El Salvador

“…Additional extensions of this work could also expand the examination of social and economic factors that determine fire occurrence and develop a fire risk model to be used by regional authorities. Xystrakis et al [49] examines the intertwinement of socioeconomic factors and burn patterns. Their work highlights the relationship between fire processes and decision making related to land use and socioeconomics.…”

Temporal variations and change in forest fire danger in Europe for 1960–2012

“…Socioeconomic variables like unemployment and touristic pressure could be directly linked to area burned (Koutsias et al, 2010; Ganteaume and Jappiot, 2013) or major social processes, as, for example, rural migration and urbanization followed by land abandonment could indirectly favour fuel conditions that could lead to large fire events as long as the fire is initiated (Koutsias et al, 2012). Similarly, humid-cool weather conditions could control fire initiation and spread even in the most fire prone ecosystems, indicating the dual role of weather in controlling fire size (Xystrakis et al, 2014). It can be argued that fire weather triggers or inhibits the landscape, topographic and socioeconomic variables in emerging as dominant factors of fire spread (Bradstock, 2010;Moreira et al, 2011).…”