Effects of Herbivory on Plant and Soil Characteristics;Allometric Relationships Change among DifferentGrazing Sites

In this study we developed and compared allometric relationships at thebranch and at the whole plant levels of artemisia sieberi in three grazing ratetreatments in miandasht protected area, iran. three 100 m2 plots in nograzed,mildly-grazed and over-grazed sites were selected. in each plot foursoil samples and five a. sieberi were randomly selected for laboratoryanalyses. for the soil samples, bulk density, soil water content, soil organicmatter, ph, n and p were measured. for the plant samples, density (m-2), bd,ca and aboveground biomass were determined. coarse and fine rootsbiomasses were measured in different soil depths in six soil sample columnstaken per plot. vegetation coverage was significantly lower for the overgrazedsite than the two other sites but the density of a. sieberi was highestfor the mildly-grazed site. correlations among plant characteristics weresignificant for all three sites. all of the relationships were significant amongthe three sites. coarse and fine roots biomasses were highest and lowest forthe mildly- and over-grazed sites, respectively. aboveground biomass washighest for the mildly-grazed and then for the no-grazed and over-grazedsites, respectively. vertical distribution pattern of fine root biomass was notsignificantly different between the no-grazed and mildly-grazed sites (p >0.05) but it was significantly different for the over-grazed site. this studyalso revealed that a light grazing in some cases may increase vegetationbiomass.