Seed dispersal dynamics in northern Iran: a comparative analysis of native large mammals and domestic sheep.

backgroundSeed dispersal through endozoochory plays a fundamental role in maintaining plant population dynamics, genetic connectivity, and habitat resilience, particularly in mountainous biodiversity hotspots. Large herbivores and omnivores can facilitate this process by transporting viable seeds across fragmented landscapes. However, the functional differences in dispersal capacity between native and domestic herbivores remain poorly understood. This study compares the seed dispersal effectiveness of three native large mammals Caspian red deer (Cervus elaphus maral), wild goat (Capra aegagrus), and brown bear (Ursus arctos syriacus) with domestic sheep, within the Central Alborz Protected Area (CAPA), northern Iran.

resultsFrom 226 scat samples collected across elevations of 2300–3850 m, 264 seedlings belonging to 40 plant species germinated. Brown bears showed the highest dispersal effectiveness (IEd = 46.6), dispersing seeds of 14 species from 100 plant bases across 30 samples. Red deer followed (IEd = 23.1; 117 plant bases; 18 species; 91 samples), with wild goats (IEd = 3.3) and domestic sheep (IEd = 2.5) ranking lower. Plant species overlap among animal groups was minimal, with the highest similarity between brown bear and domestic sheep (IM = 0.089), and no overlap between red deer and wild goat.

conclusionNative large mammals are key contributors to the dispersal of diverse native and endemic plant species in CAPA. In contrast, domestic sheep exhibit low dispersal effectiveness and tend to propagate non-native or invasive flora. These findings underscore the ecological importance of preserving native large mammal populations and implementing rewilding and grazing management strategies to safeguard plant diversity and ecosystem function in alpine environments under increasing anthropogenic pressure.