Diseases and Pests Harming Ecosystem Services in Urban Green Spaces of the Mediterranean Region

In recent decades there has been an upsurge of disease and insect attacks in trees of the Mediterranean region. At the same time, new pathogens and pests are being reported from urban and peri-urban forests at a rate never observed before. These biotic disease agents pose a serious threat to urban green spaces and to the ecosystem services they provide. The disease phenomenon is related to an increase in drought events, which are more pronounced in the Mediterranean area than elsewhere, being this an hotspot area for climate change. A number of thermophilic or thermotolerant fungi, such as some members of the Botryosphaeriaceae and Xylariaceae, as well as insect pests such as Rhynchophorus ferrugineus and Matsucoccus feytaudi, are causing extensive disease and mortality to trees in urban green areas. Such an increase in disease and insect outbreaks is in part also due to the exceptionally mild winters of recent years, which are enabling an everincreasing number of infectious propagules and insects to survive through the winter. Clearly, these biotic disease agents are also undermining essential ecosystem services provided by urban greenery, such as carbon sequestration, urban microclimate mitigation, dust and noise abatement, or opportunities for tourism and recreation. Current climate trends suggest that in choosing tree species for planting in urban and peri-urban areas, more attention should be paid in future not only to the tolerance of these trees to abiotic stresses, but also to their resistance to pathogens and pests.