Investigating Biome-wide Shifts in Mediterranean Pine Forests Using Earth Observation Data

Mediterranean thermophilous pines, which are the key, dominant, and characteristic species of this habitat, form some of the most drought-resilient woodlands in Europe. Although these species are well-adapted to long, dry periods, the increasing intensity and frequency of droughts in recent years have exceeded the resilience of these ecosystems in certain areas. This has resulted in declining forest health, degradation, and increased tree mortality. Furthermore, because these ecosystems lie at the climatic limits of tree lifeforms, the loss of tree cover in Mediterranean pine forests can trigger a significant shift in ecosystem structure—from woodlands to shrublands, grasslands, or even bare ground. Such transitions can accelerate desertification and cause cascading impacts on biodiversity throughout the entire ecosystem.

In this study, the aim is to demonstrate the added value and additional insights that can be obtained from Earth Observation-derived climate information, which extends beyond widely used bioclimatic variables. While these traditional bioclimatic variables have proven helpful for the species distribution modelling community, it is increasingly recognised that many of them serve as proxies rather than direct representations of the fundamental drivers of species distributions. By establishing more direct connections with novel ECVs—for example, the permafrost ECV—we aim to create stronger and more generalisable links between dominant tree species in key ecosystems and Earth Observation-derived climate data. This approach is expected to be relevant not only for the two ecosystems highlighted in this case study, but also for all recognized biomes dominated by tree species.