Restoring Mediterranean holm oak forests: ecosystem functioning and climate mitigation in the LIFE RECLOAK project

Mediterranean forest ecosystems are currently facing severe challenges due to the combined pressures of biotic and abiotic stressors. In particular, Holm oak (Quercus ilex L.) forests are experiencing a widespread decline driven by the effects of climate change-induced drought and the aggression of the soil pathogen Phytophthora cinnamomi. This decline threatens not only forest biodiversity but also the stability of essential ecosystem services. In response to this problem, the LIFE RECLOAK project aims to restore and improve the conservation status of these threatened habitats. The project adopts an approach involving the genetic selection of drought-tolerant and pathogen-resistant genotypes, their micropropagation, and subsequent planting in pilot sites across Italy, Spain, and Malta. Within this framework, Work Package 7 (WP7) is dedicated to the "Evaluation of ecosystem functioning and climate mitigation effects," validating the success of the reforestation efforts. Therefore, the primary objective of WP7 is to quantify the restoration of ecosystem processes and the enhancement of climate change mitigation potential provided by the selected resistant genotypes compared to traditional forest stock.

The activities of WP7 integrate field monitoring and modelling tasks. Firstly, the project will assess vegetation growth and biodiversity. In the pilot sites, key morphological parameters of Q. ilex (such as Basal Diameter (BD), Plant Height (PH), and Leaf Area Index (LAI)) will be measured annually to track biomass accumulation. Concurrently, biodiversity indexes (BI) will be calculated to monitor the recovery of understory vegetation. To evaluate the restoration of below-ground processes, soil quality will be assessed through measurements of soil respiration, Soil Organic Carbon (SOC), erosion rates, and Water Holding Capacity (WHC). Recognizing the slow growth rate of holm oaks, these monitoring activities are planned to continue for ten years after the project's conclusion, ensuring a long-term perspective on ecosystem recovery. Data collected from vegetation and soil monitoring will be used for the assessment of carbon sequestration, calculating the CO₂ absorbed by both the woody biomass and the soil compartment. WP7 will also develop a monitoring tool using the Biome-BGC Musso ecohydrological model. By integrating site-specific pedoclimatic data with the physiological traits of the resistant genotypes, this model will be calibrated to simulate carbon and water pathways (e.g., Water Use Efficiency) over the plantation's lifespan. This approach quantifies the added value of the resistant genotypes, demonstrating their superior resilience under changing environmental and management conditions.

Finally, under the coordination of the Democritus University of Thrace, WP7 will integrate these findings to analyze broader Ecosystem Services (ES), including provisioning, regulating, and supporting functions. Ultimately, by validating biological indicators and establishing a robust carbon monitoring protocol, WP7 will demonstrate the effectiveness of using improved genotypes, offering a replicable model for restoring Mediterranean areas affected by forest dieback.