Reaction of Growth Season Against Climatic Drought and Wet Year

Central area of Baluchestan with an area of about 42510 km2 has a warm and arid climatic conditions. vertical radiation، degree of radiation absorption، high temperature، low precipitation and consequently poor vegetation cover are the main characteristics of this region. While sudden precipitations under the effect of Gang-Pakistan low pressures، can have a positive effect on the growth and development of vegetation cover in the area، which has caused opposite، different and oscillating climatic behaviors in the region. The existence of such special conditions justifies the study and review the behaviors'' relation (oscillations and anomalies)، precipitation and temperature with potential changes of vegetation cover by using Qgs climatic equation. With respect to the obtained Qgs values for the climatic period (1987-1997) (the wet period of the region) which is lower than the climatic period of 1998-2003 (the dry period of the region)، therefore، the tension resulting from drought in the areas with a higher Qgs value، is more and on the contrary، in the areas with lower Qgs، the grass lands of the area has had a better condition. on this basis، during the under study statistical years، the grass land sites located at Piranshahr area in comparing with the sites located at Nikshahr town ship area has faced with a lower shortage of water. consequently، the irregular behaviors of precipitation during the recent years has caused more damages to Iranshahr''s green grass lands. Also due to the low height difference between the two regions، the height factor could not protect Iranshahr''s grass land against the serious damages of water shortage in comparing with the grasslands of Nikshahr with a lower height.