Study on Vegetation Changes of Natural Ranges in KhoyBilehvar Semi-Steppic Area of West Azarbaijan Province

Abstract

The study of the exclosure effects on the vegetation changes under<br />grazing and non-grazing conditions in the rangeland areas has particular<br />importance in the rangeland improvement and revivification projects. The<br />research was accomplished in semi-steppe KhoyBilehvar area, from 1999 to<br />2005. Vegetation cover was annually measured within fixed plots during transact.<br />The results showed that during nine years of research, on KhoyBilehvar<br />exclosure, the total canopy cover has increased inside the exclosure, and the<br />highest increase was observed in the perennial grasses (more than 3.5) and<br />perennial Forbs (more than 2.5). Outside the exclosure, the total vegetation cover<br />was almost constant and changes were less in vegetation cover types. Within the<br />exclosure, some desirable species appeared consisting almost 19% of vegetation<br />composition. Medium species proportion in the plant composition increased to<br />more than two times and undesirable species decreased by half. Whereas, outside<br />the exclosure, scarce desirable species and medium species of vegetation ratio<br />has increased a little. The vegetation average of annual species during the study<br />within exclosure is more than outside and the vegetation average of forbs inside<br />and outside the exclosure is more than annual grasses. Nine year research in<br />Bilehvar exclosure showed that the correlation between precipitation changes and<br />vegetation cover was significant in the most species.