Millennial-scale climatic variability and fire regimes and their impacts on vegetation in Gran Canaria since since 28 cal ka BP

Abstract

The influence of climate change and fire regimes on vegetation in the Canary Islands at the millennial scale remains largely unknown. This study presents the longest continuous palaeoecological record from the archipelago, spanning the last 28,000 years from Vega de Arucas in Gran Canaria. Using a multiproxy approach, we analysed charcoal particles for fire frequency reconstruction, fossil pollen and non-pollen palynomorphs (NPPs) for vegetation change, sedimentology for changes in material deposited, branched glycerol dialkyl glycerol tetraethers (brGDGTs) for air temperature, and pollen climate modelling for temperature, precipitation, and relative humidity estimates. We document different changes in vegetation and fire regimes linked to regional and global climatic transitions. Before the Last Glacial Maximum (LGM), pollen and charcoal data indicate local presence of a laurel forest taxa (e.g., Morella faya) at low elevations (c. 200–300 m above sea level), subjected to infrequent fires, suggesting wetter conditions and cooler temperatures. During the LGM, the laurel forest was replaced by a dry pine forest, indicative of lower than previous temperatures and reduced water availability. This transition from laurel to pine forest coincides with an increase in fire frequency. During the last deglaciation (Bølling-Allerød and Younger Dryas), a rapid shift occurred from pine forest to thermophilous woodland (e.g., Juniperus sp., Phoenix canariensis), reflecting warmer conditions with continued climate oscillations and more frequent fire activity. Although pollen preservation was poor during the Holocene and hampers current understanding of vegetation changes throughout this period, charcoal records indicate frequent fires. While previous views have proposed that islands may have been buffered from climatic changes due to the regulating influence of the ocean, our study confirms a scenario of direct influence of global and regional climatic variations in local vegetation distribution and fire regimes. This has important implications for understanding vegetation resilience and landscape management in the face of future climatic changes.