Microbial diversity in desert ecosystems

2 ) covers area defined as semi-arid deserts ex- cluding Antarctica. Due to extreme variations in geocl i- matic patterns, the global arid biome consists of highly diversified and heterogeneous ecosystems. The dry climates of the continents occur in five great provinces separated from one another by oceans or by wet equatorial zones. Of these five provinces, North Afr i- can-Eurasia is larger than rest of the four combined. The world's largest desert Sahara and a series of other hot d e- serts and semi-arid areas continue eastward through the Arabian peninsula along the Persian Gulf of Pakistan, and India fall in this province 2 . It also includes cold deserts from states of the former Soviet Union through China to Iran. The tropical desert of Asia extends to India through Rajasthan and Gujarat where it is called the Thar. The Thar lies west of Aravalli Range in Rajasthan and covers an area of about 196,150 km 2 . It is subjected to intense winds and wide variations in temperature ranging from a minimum of 5°C to a maximum of 45°C. It is dotted with numerous water reservoirs including four major inland saline playas.