Recent Anthropogenic Plant Extinctions Differ in Biodiversity Hotspots and Coldspots

• Published in: Current biology 2019-09, Vol.29 (17), p.2912-2918.e2
• Main Authors: Le Roux, Johannes J., Hui, Cang, Castillo, Maria L., Iriondo, José M., Keet, Jan-Hendrik, Khapugin, Anatoliy A., Médail, Frédéric, Rejmánek, Marcel, Theron, Genevieve, Yannelli, Florencia A., Hirsch, Heidi
• Format: Article
• Language: English
• Subjects: anthropocene; biodiversity hotspot; coldspot; Environmental Sciences; extinction debt; extinction drivers; extinction rate; global plant extinctions; plant life-form; taxonomic uniqueness
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2019.07.063

During the Anthropocene, humans are changing the Earth system in ways that will be detectable for millennia to come [1]. Biologically, these changes include habitat destruction, biotic homogenization, increased species invasions, and accelerated extinctions [2]. Contemporary extinction rates far surpass background rates [3], but they seem remarkably low in plants [4, 5]. However, biodiversity is not evenly distributed, and as a result, extinction rates may vary among regions. Some authors have contentiously argued that novel anthropic habitats and human-induced plant speciation can actually increase regional biodiversity [6, 7]. Here, we report on one of the most comprehensive datasets to date, including regional and global plant extinctions in both biodiversity hotspots (mostly from Mediterranean-type climate regions) and coldspots (mostly from Eurasian countries). Our data come from regions covering 15.3% of the Earth’s surface and span over 300 years. With this dataset, we explore the trends, causes, and temporal dynamics of recent plant extinctions. We found more, and faster accrual of, absolute numbers of extinction events in biodiversity hotspots compared to coldspots. Extinction rates were also substantially higher than historical background rates, but recent declines are evident. We found higher levels of taxonomic uniqueness being lost in biodiversity coldspots compared to hotspots. Causes of plant extinctions also showed distinct temporal patterns, with agriculture, invasions, and urbanization being significant drivers in hotspots, while hydrological disturbance was an important driver in coldspots. Overall, plant extinctions over the last three centuries appear to be low, with a recent (post-1990) and steady extinction rate of 1.26 extinctions/year. •Global plant extinction rates are low but notably higher than background rates•Plant extinctions are higher in biodiversity hotspots than in coldspots•Certain plant life forms are more prone to extinction than others•The causes of recent plant extinctions vary over time Le Roux et al. show that contemporary plant extinction rates, while low, far exceed historical background rates. They find extinctions to be higher, and accruing faster, in biodiversity hotspots than in coldspots and that the latter loses more unique taxonomic diversity to extinction. They also find the drivers of extinctions to vary over time.