Predicting the Potential Distribution of Jujube (Ziziphus jujuba Mill.) in Iran

Species distribution models (SDMs) are predictive models for species’ geographic distributions which are in association with environmental factors and presence of species. SDMs are important for a variety of applications in systematics, ecology, and conservation. The genus Ziziphus Mill. (Rhamnaceae) comprises six species in Iran including Z. spina-christi, Z. nummularia, Z. jujuba, Z. mauritiana, Z. lotus, and Z. oxyphylla. Out of which, Z. jujuba is a common species of the genus.

In this study, 43 occurrences of Ziziphus jujuba were recorded and used in the maximum entropy distribution modeling approach (MaxEnt) with five environmental variables. Three important variables: bio6 (Min Temperature of Coldest Month, 24.3%), bio8        (Mean Temperature of Wettest Quarter, 23%), bio9 (Mean Temperature of Driest Quarter, 20.5%) include 67.8% of all percentage contribution in the final model.

Slope, five temperate and two precipitation variables influenced our final model. The most suitable habitats are located in eastern Iran which completely corresponds to South Khorasan province and central Iran. Additionally, the species is distributed in northern Iran as well but our model doesn’t show northern Iran as the most suitable habitat for Z. jujuba which probably related to the species has been cultivated in that place.

Temperature is one of the most important factors in the distribution of Z. jujuba and it is compatible with that Jujube trees raise in arid and semiarid zones. However, the predictable habitats are distributed in central and eastern Iran which partly corresponds to South Khorasan province.