Prioritizing conservation areas based on contributions to rarity and beta diversity in Mediterranean forest ecosystems in Türkiye

Abstract

The depletion of forest biodiversity arising from insufficient conservation of resources due to wood extraction, overgrazing, fire, and land use presents a significant challenge in the Mediterranean region. It becomes crucial to identify priority conservation areas for safeguarding biodiversity. We used plant species data taken from 800 plots in the Kuyucak mountain district, a typical Mediterranean forest ecosystem in Türkiye and maps of seven potential environmental predictors: elevation, aspect, slope, head index, topographical position index, landform characteristics, and bedrock geology. To assign priority areas for the conservation, local contribution to beta diversity (LCBD) and relative contribution to total rarity (RIRR) were examined with community metrics and environmental predictors, respectively. Correlation results showed that LCBD was positively related to rare species richness but negatively related to common species richness. RIRR was significantly associated with all the community metrics. According to the results of Random Forest regression models, elevation was the most important variable of LCBD, followed by slope, heat index, and pebblestone. For RIRR, the most contributed variables were elevation, heat index, limestone, and slope, respectively. The LCBD and RIRR Random Forest regression models were extrapolated along the Kuyucak mountain district, resulting in the creation of potential distribution maps for both LCBD and RIRR. Subsequently, from these maps, two distinct conservation value maps have been developed for the Kuyucak mountain district based on four conservation priority classes (Priority Class 1, Priority Class 2, Priority Class 3, and Priority Class 4): one employing a conservation cost approach and the other applying an ecology-centered approach. The results suggest that areas with elevated values of both LCBD and RIRR values are primarily situated below 1100 m on steep valley slopes, characterized by the presence of karstic limestone and intricate terrain. Compared to other areas, prioritizing the protection of such areas can provide greater benefits in contributing to ecological uniqueness. Keywords: Community rarity, Species contributions to beta diversity, Conservation priority, Ecological uniqueness, Indicator species analysis, Machine learning