Mosaic Landscape Pattern Explains Vegetation Resistance to High Fire Frequency in Corsica over the Last Six Millennia

Abstract

1. Significant pine mortality has been observed in mountainous areas with a Mediterranean climate over recent decades, impacting ecosystem function and economic management of these forests. Despite this, few studies have examined how forest management can interact with disturbances to influence pine mortality. 2. We used process-based models to quantify the spatial distribution of a typical vegetation assemblage of Corsican pine forests, and evaluate how different landscape patterns and fire regimes (i.e. burned area and fire intensity) affect plant communities. For all 18 scenarios examined, fire return interval was fixed at 100 ± 70 years that corresponded to the mean ± standard deviation reconstructed for the last 6000 years in this ecosystem. 3. Results indicate that the most species diverse Corsican pine ecosystems over the past 6000 years of history are best explained by a high fire frequency of small fires that cover a large area in total in a climate comparable with today. An increase in mean annual temperature of 1 or 2 °C is sufficient to decrease the diversity of the ecosystem. In addition, a mosaic landscape pattern is correlated with high plant species diversity, and is associated with medium to low fire intensity, and small burned areas (3 to 5% of the landscape). 4. Synthesis and applications: The diversity of the Corsican pine forest as recorded in the past 6000 years is likely explained by frequent fires of medium to low intensity. Thus, we encourage pine forest management in Corsica (and in the Mediterranean mountain belt) to use frequent disturbances, such as clear felling, to promote a mosaic landscape that facilitates species diversity and presence of Corsican black pine.