Increasing temperatures can pose an opportunity to recover endemic and endangered oriental sweetgum tree (Liquidambar orientalis Mill.) from extinction

Abstract

Evidence suggests that past climatic oscillations caused many species to drastically change their distribution range and had significant impacts on their survival capabilities. There is significant evidence suggesting that today’s changing climate threatens many species to face a rapid extinction period in the coming decades and centuries. Understanding the changing range patterns provides significant input on biodiversity and conservation biology studies. However, warming climatic conditions may also present an opportunity for some species to expand their habitats—particularly those adapted to warmer environments. In this study, we asked how near-future climate change will affect the distribution range of the oriental sweetgum tree (Liquidambar orientalis Miller, 1867) which is a deciduous tertiary relict endemic species that forms the riparian forest ecosystems across southwestern Türkiye and Rhodes Island (Greece). Oriental sweetgum is on the verge of extinction due to past climate changes and current anthropogenic pressures such as deforestation and improper farming practices as well as insufficient conservation policies and efforts in place. As a result, sweetgum trees only survive in fragmented forest patches. To understand the species’ possible response to globally rising temperatures, we explored the ecological and climatic factors that drive the distribution changes using a species distribution modeling approach. We predicted species’ past (Mid-Holocene, approximately 6000 years ago), current, and future (2070) distribution ranges using maximum-entropy (MaxEnt) niche models built with WorldClim Version 1.4 climatic data. We found that regular water and warmer temperatures are particularly crucial for this species. The models showed a past (Mid-Holocene) expansion in suitable habitats in response to warmer conditions followed by a contraction as temperatures cooled down to the current climate. Most importantly, our future predictions showed that the species can possibly expand its distribution range to newly suitable habitats exhibiting a similar past response to the increasing temperatures. In this scenario, however, we suggest that it is extremely important to take necessary restoration and conservation steps for fragmented sweetgum forests to ensure species survival in the next centuries. We also believe that further research must be conducted to better understand species’ ecological requirements and to provide crucial knowledge for future conversation approaches.