Climate change impact on the population dynamics of exotic pathogens: The case of the worldwide pathogen Phytophthora cinnamomi

Worldwide, Mediterranean-climate type forests are seriously threatened by climate change and Phytophthora cinnamomi, an extremely aggressive soilborne pathogen listed among the 100 worst invasive alien species. This study examines for first time effects of annual seasonal changes in temperature rainfall under different climatic scenarios on P. cinnamomi dynamics a Mediterranean forest naturally infested. We followed seasonally during four years (2016–2020) abundance soil taking advantage infrastructure that simulates 30% reduction using rainout shelters increase open top chambers. Seasonal was strongly linked to spring precipitation: large inoculum density this season suffered strong decrease dry summer maintained until next spring, despite fall rains. Thus, may be considered best indicator potential infection natural ecosystems. The two treatments had significant abundance, but only some combinations seasons years. Rainfall exclusion negative effect mostly wet years, causing as comparison with control treatment. Meanwhile, warming varied from slightly winter positive early summer, increases 31% Overall, we provide novel experimental evidence suggesting drier might limit activity water-limited forests, at least partly counteracted warming. These results also imply represents increasing threat conservation ecosystems where water is not limiting factor.