Investigating the Possibility of Defining the Boundaries of Vegetative Regions of Iran Based on Variations in Plant Species

In ecology, the gradual changes in any environmental factor (gradient) with the change in species composition and growth forms are illustrated as a boundary. Defining the boundaries of the vegetative regions of Iran is a fundamental issue for ecosystem management specially the management of plant vegetation. In this study, the ecological boundary of the vegetative regions of Iran (i.e., Irano-Turanian steppe/mountainous vegetative region, Irano-Turanian desert vegetative region, and Zagrosi vegetative region) presented in Pabo’s map was identified, analyzed, and reevaluated across the climatic gradient. The present study was carried out in the climatic gradient of Dena-Tabas. This climatic gradient encompasses the three aforementioned vegetative regions. Dispersion indices including half changes, beta diversity, and standard deviation were used to identify the ecological boundary of plant communities. The results indicated that the length of the gradient was 8.06 SD and 15.13 Hc. Considering the changes in the species composition, the boundary of these three vegetative regions presented in Pabo’s map did not match with the ecological boundary identified by Hc index with the beta diversity above 50 percent. It can be argued that by calculating half changes and beta diversity, the boundary between the vegetative regions can be identified or corrected with a higher degree of certainty.