Afforestation after land abandonment as a nature-based solution in Mediterranean mid-mountain areas: Implications and research gaps

Management policies after abandonment in Mediterranean mid-mountains have encouraged the establishment of afforestations being considered as an NBS. Related to the implication on soil afforestation can (i) accelerate the recovery of some soil proper-ties but it is necessary for long time periods, (ii) change above-and belowground litter quality and quantity producing a constant SOC accumulation, (iii) improve aggregate stability, and (iv) in-crease the presence of macro-aggregates and the water holding capacity of the soil. Likewise, afforestation threatens water re-sources: (i) reduces the number of floods; (ii) decreases annual water yield; (iii) delays peak flows but increases the duration of floods; (iv) increases interception of rainfall, and (iv) typically re-duces the erosion risk and the volume of sediment, but not during the first years due to high geomorphic activity. However, there is still considerable scientific uncertainty and research on the im-pacts of afforestation in soil and water conservation is still needed.

Automated summary

Management policies in Mediterranean mid-mountains after abandonment have promoted afforestation as a nature-based solution (NBS). Afforestation can accelerate soil property recovery over long periods, change litter quality and quantity, improve aggregate stability, and increase water holding capacity. However, afforestation also threatens water resources by reducing floods, decreasing annual water yield, delaying peak flows, increasing rainfall interception, and reducing erosion risk and sediment volume in the long term. Scientific uncertainty still remains, and more research on the impacts of afforestation on soil and water conservation is needed.