Effectiveness of the protected area for the plant species diversity conservation under the changing climate

Protected areas (PAs) play a crucial role in safeguarding biodiversity, but their effectiveness under climate change remains uncertain. Studies suggest that PAs are often biasedly distributed, potentially limiting their ability to protect important wildlife. This study assesses whether Japan’s PAs can serve as refugia for native temperate plant species under future climate scenarios. Approximately 20.5% of Japan’s total land area is designated as PAs, categorized into three ranks based on the strictness of legal protection. The study considered 2,260 native temperate plant species and used climate data from the WorldClim database, incorporating 12 general circulation models (GCMs) and four shared socioeconomic pathways (SSPs). Species distribution models were developed using MaxEnt to predict changes in species richness, habitat availability and extinction likelihood for native temperate plants under two migration scenarios: full migration, where species can freely shift ranges, and no migration, where species remain within current habitats. The results showed significant variability in species richness across GCMs within the same SSP scenario. As global CO 2 concentrations increase, species richness is projected to decline, with greater losses in the no migration scenario compared to full migration. Despite these losses, even under the extreme SSP585 scenario and no migration, most native temperate plant species are expected to retain over 50% of their potential habitats within PAs, resulting in a low risk of species extinction from all PAs. These findings suggest that Japan’s native temperate plant species may retain their potential habitats within PAs even under the most extreme climate scenarios.