Will dragonblood survive the next period of climate change? Current and future potential distribution of Dracaena cinnabari (Socotra, Yemen)

The potential impact of climate change on Dracaena cinnabari, a spectacular relict of the Mio-Pliocene Laurasian subtropical forest in Socotra (Yemen), was analysed. Current distribution, abundance and vertical structure of D. cinnabari populations were assessed with 74 plots in nine remnant areas. A deterministic regression tree analysis model was used to examine environmental variables related to the current species distribution. Using this model, a current potential map and a predicted potential map for the ∼2080 climatic scenario were generated. D. cinnabari has an altitudinal range from 323 to 1483 m a.s.l., with a mean annual temperature of 19.8–28.6 °C and an annual precipitation of 207–569 mm. The current distribution and abundance of D. cinnabari is correlated to three factors: moisture index (i.e. the ratio between the annual precipitation and potential evapotranspiration), mean annual temperature and slope. According to this model, D. cinnabari occupies only 5% of its current potential habitat. This potential habitat is expected to be reduced with 45% by 2080 because of a predicted increased aridity. Only two out of the nine remnant areas should be considered as potential refugia. The boundaries of the strictly protected Skund Nature Sanctuary, where no (road) infrastructure is allowed, should be extended to include both areas. The construction of new roads leading towards these areas, thereby increasing permanent settlements and grazing pressure, should also be discouraged.