Charting trends in the evolution of the La Alhambra forest (Granada, Spain) through analysis of pollen-emission dynamics over time

Abstract

Changing climate conditions are having an appreciable impact both on the adaptive response of the species growing in urban and peri-urban forests (UPF) and on their evolutionary dynamics. This study sought to chart the evolution and pollen dynamics of major species growing in the La Alhambra peri-urban forest (Granada, Spain) over the last 22 years, to examine correlations with weather-related parameters and to estimate potential trends in the event of future climate change. Findings showed that overall pollen levels have gradually increased over the study period, reflecting both plant species diversification and the ability of Mediterranean species—particularly Pinus and Quercus—to adapt to short-term water stress situations. Nevertheless, the climate conditions expected over the coming years in the Mediterranean region, with considerable increase in winter temperatures and a drop in precipitation by up to 24 % for summer rainfall, there is likely to be a reduction in the intensity of pollen emissions, at least from species with strict environmental requirements. The results confirm that pollen emission is a valuable biological indicator for estimating the adaptive response of various species and the resilience of the forest mass to climate-change events.