Fires are among the most damaging disturbances to forests in the Mediterranean area. The study analyses the occurrence and characteristics of forest fires in Eastern Spain (1993–2015) to identify key variables related to burnt forest land, differentiating fires according to their burnt area. Data are retrieved from digital cartography, the Spanish Forest Map and data concerning fires. Based on previous research, the variables included are altitude, slope, aspect, fuel, species, population and road density. The fires are classified in small (5–50 ha), medium (50–500 ha) and large (> 500 ha). Four models are considered to explain the proportion of burnt area based on weighted generalized linear models: a general model and one per size class. The results highlight the different relations of similar variables with fires according to the size. When a single model is considered to explain all area burnt, the relationships are mainly driven by large fires. The larger area is burnt on forests with pine, bushes and small trees, whereas smaller fires tend to occur on lower altitude, low slope, high population and road densities. There are large differences in the variables according to the fire sizes, especially for the presence of pine (negative in the medium fires model but positive for the large fires model) and Pasture (which only explains the small fires). The models can be applied to analyse occurrence by fire size in Mediterranean areas, and the results can help elaborate fire prevention strategies and land-planning schemes.

中文翻译：

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影响西班牙东部地中海森林火灾发生的变量的大小依赖性

火灾是对地中海地区森林破坏最大的干扰之一。该研究分析了西班牙东部（1993-2015 年）森林火灾的发生和特征，以确定与燃烧林地相关的关键变量，根据燃烧面积区分火灾。数据是从数字制图、西班牙森林地图和有关火灾的数据中检索到的。根据之前的研究，包括的变量包括海拔高度、坡度、坡向、燃料、物种、人口和道路密度。火灾分为小型（5-50 公顷）、中型（50-500 公顷）和大型（> 500 公顷）。考虑了四种模型来解释基于加权广义线性模型的烧毁面积比例：通用模型和每个尺寸等级一个。结果突出显示了类似变量与火灾大小的不同关系。当考虑使用单一模型来解释所有燃烧区域时，这些关系主要是由大火驱动的。较大面积的火灾发生在有松树、灌木和小乔木的森林，而较小的火灾往往发生在低海拔、低坡度、高人口和道路密度的地方。根据火的大小，变量存在很大差异，特别是松树（中火模型为负，大火模型为正）和牧场（仅解释小火）的存在。该模型可用于分析地中海地区火灾规模的发生情况，其结果有助于制定防火策略和土地规划方案。灌木和小树，而较小的火灾往往发生在低海拔、低坡度、高人口和道路密度。根据火的大小，变量存在很大差异，特别是松树（中火模型为负，大火模型为正）和牧场（仅解释小火）的存在。该模型可用于分析地中海地区火灾规模的发生情况，其结果有助于制定防火策略和土地规划方案。灌木和小树，而较小的火灾往往发生在低海拔、低坡度、高人口和道路密度。根据火的大小，变量存在很大差异，特别是松树（中火模型为负，大火模型为正）和牧场（仅解释小火）的存在。该模型可用于分析地中海地区火灾规模的发生情况，其结果有助于制定防火策略和土地规划方案。特别是对于松树（在中火模型中为负，但在大火模型中为正）和牧场（仅解释小火）的存在。该模型可用于分析地中海地区火灾规模的发生情况，其结果有助于制定防火策略和土地规划方案。特别是对于松树（在中火模型中为负，但在大火模型中为正）和牧场（仅解释小火）的存在。该模型可用于分析地中海地区火灾规模的发生情况，其结果有助于制定防火策略和土地规划方案。