Relationship between cover and yield of some range species in steppic region of Yazd province.

Sustainable range management needs the accurate estimation yield and determining of grazing capacity in rangelands. it is easy to obtain yield estimation with indirect methods.for this purpose, the relation between cover and forage yield of range species were studied in steppic rangelands of yazd. measurements of cover and forage yield were carried out with plot area and clipping and weighting methods, respectively. every year,one hundred and twenty quadrate plots were systematically assessed from 2000 until 2004 in mid-may. in addition to mentioned measurement, four sampling was done until early november in 2004. data were analyzed in regression and correlation programs (spss 10.0).results showed that there was significant relation (p<0.01) between cover and forage yield of studied species during 4 years (2001-2004), but 3 species out of 7 studied species had significant relation in 2000-drought year (p<0.05). obtained relations and also fitted models were varied in different years and stages. therefore, the yield estimation is possible by using cover, but in dry years. these characteristics are applied for annual yield estimation of steppic range species by double sampling model with cover.