role of functional groups of dung beetles on secondary seed dispersal by removing sheep dung case study: shahrekord rangelands)

the present study was conducted to assess the effect of dung beetles on sheep dung removal and seed dispersal in semi steppe rangelands of shahrekord province with poor condition located in iran. therefore, the large (1 cm2) and small size (1 mm2) meshes were used and filled by sheep dung in six treatments. to evaluate the role of the insects in seeds translocation, three sizes of plastic beads used as seed mimic. the results illustrated that the maximum function of the insect was observed in the possible treatment of the presence of dwellers, absent of large tuneller and large roller beetles and present of small tuneller and small roller beetles. the least dung removal was calculated in the control treatment and possible treatment of dwellers, large and small tunneler and also absent of large rollers and presence of small rollers respectively. seed removal decreased in the order of small size (29) > medium size (5) > large size (2). in general, dung beetles play an important role in dung removal and secondary seed dispersal, but their function relates depended on habitat condition. in a degraded ecosystem, this insect will disappear. considering the various factors affecting the function of these insects, further studies would be needed for investigating deeply different seasons and dung of different livestock feeding on the rangelands.