Changes in the Potential Distribution of Atlas Cedar in Morocco in the Twenty-First Century According to the Emission Scenarios of RCP 4,5 and RCP 8,5

Abstract

The increasing temperatures and decreasing rainfall are expected to have negative effects on ecosystem services causing significant shrinkage or shift in forest distributions particularly in the Mediterranean basin. In this study, we aimed to determine the distribution of Atlas cedar (Cedrus atlantica Manetti), modeling the current and potential future distributions in Morocco with Maximum Entropy (MaxEnt) approach. Modeling was performed using all bioclimatic variables that show a significant relationship to the current distribution of Atlas cedar and that were specifically preferred in the literature by several similar studies. Prediction of warmer future scenarios showed that populations in the potential area would decrease by 21% for RCP 4.5 (2050), by 23% for RCP 4.5 (2070), by 35% for RCP 8.5 (2050), and 41% for RCP 8.5 (2070) and that there would be an impact in all ranges including the Cedar Biosphere Reserve in Morocco. Similarly, the Atlas cedar would lose its isolated-marginal populations in its southern and western extents. The results underline the importance of a genetic conservation program for cedar populations in Morocco. Otherwise, gene pools seem to turn extinct due to climate change. Furthermore, this study is intended to provide a starting point for continuous monitoring of Atlas cedars distributions while observing its climatic migration. Species distribution modeling generates valuable information for conservation management strategies for this endemic, rare, and threatened relict tree species. The results can be used to identify high-priority areas for Atlas cedar restoration and conservation against the expected impact of climate change.