Application of the Global Bioclimatic Classification to Iran: implications for understanding the modern vegetation and biogeography

Abstract

This study aims at proposing a new bioclimatic zonation for Iran based on the recently developed Global Bioclimatic Classification System (GBC) and tries to re-appraise this classification system by checking the degree of correspondence between its bioclimatic zones and the distribution of major phytogeographical regions, biomes, and a selection of plant and insect taxa of Iran. After application of the GBC to Iranian meteorological data, three macrobioclimates, ten bioclimates, and three bioclimatic variants were distinguished. The Mediterranean macrobioclimate is the dominant macrobioclimate and correlates with the Irano-Turanian biogeographical region, the Tropical macrobioclimate in southern Iran correlates with the Saharo-Sindian region and finally a small Temperate macrobioclimatic zone in northern Iran correlates with the Euro-Siberian region. Mediterranean macrobioclimate of Iran displays a wide range of bioclimates including Mediterranean pluviseasonal-oceanic, Mediterranean xeric-oceanic, Mediterranean pluviseasonal-continental, Mediterranean xeric-continental, Mediterranean desertic-oceanic, and Mediterranean desertic-continental. Tropical macrobioclimate also shows a range of bioclimates including Tropical xeric, Tropical desertic, and Tropical hyperdesertic. Finally, Temperate macrobioclimate has only one bioclimate i. e. Temperate oceanic. In conclusion, bioclimatic zones identified using the GBC system correlate well with the main phytogeographical regions of Iran at macrobioclimatic level and with major biomes at bioclimatic level. An advantage of the GBC over other bioclimatic classification systems is the inclusion of both seasonal and annual variations in those climatic parameters which are significant for the growth and development of plant populations and communities. GBC distinguishes several types of Mediterranean climate regimes for Iran and helps to differentiate between two different desert climate types i. e. Mediterranean and Tropical deserts in arid parts of the country. Because the climate in the Irano-Turanian region clearly differs from the Mediterranean region in its degree of continentality and seasonality, we propose the term ‘ xero-estival-continental’ or ‘Irano-Turanian’ instead of ‘Mediterranean’ bioclimate when describing the climate of continental Middle East and Central Asia.