Seed Dispersal by Domestic Herbivores in Rangeland Ecosystems of the Central Zagros Region

Abstract

To assess seed dispersal by domestic herbivores (sheep and goat) in Central Zagros region, 12 different rangeland sites, located 200 km west of Isfahan city, were studied. For each site, a pooled dung sample of 10 freshly pellet groups from domestic herbivores was collected in four different periods (mid June, July, August and September) during grazing season (in total, 48 pooled dung samples). Dung samples were dried in a dark room by exposing to open air, and then from each a 150 gram sample was kept for two months in the refrigerator at 3ْc as cold treatment. Seed content of dung samples was assessed in a greenhouse germination experiment over a period of 8 months. In total, 2039 seedlings from 50 different plant species (16 families and 48 genera) were germinated from dung samples. Seed content of dung samples was mostly composed of palatable herbaceous species with no dispersal mechanism or adaptation except for the production of many small-sized seeds. The highest and the least number of germinated seeds was observed in July and June samples, respectively. Also, the highest and the least number of seed species was recorded in September and June samples, respectively. However, only a significant difference in seed species composition was observed between dung samples of September and June. Given that most of the plant species recorded in the region’s vegetation were regenerate by seed, seed dispersal via domestic herbivore dungs may have significant role in natural regeneration of the vegetation, if other environmental and management conditions are met. The results of the present research can be especially applied to reclamation of the country’s rangeland ecosystems.

Keywords

• Dung seed content
• Grazing ecosystems
• Seed germination
• Semi-steppe rangelands
• Soil seed bank dynamics
• Vegetation natural regeneration.