The morphological characteristics and germination of grassland forb species after simulated digestion by sheep in the Tianshan Mountains, China

Viable seeds from dry-fruited forbs growing in the Tianshan Mountains of China are often found in livestock dung. However, the effect of ingestion on their morphological characteristics and germination remains unclear. This research assessed the germination of 15 forbs after simulated ingestion (insertion through a rumen fistula) by Kazakh sheep. Seed accessory structures (such as wings, trichomes and mucilage) were digested. Seed length, width and thickness were negatively correlated with digestion time, and 100-seed mass was negatively (but not significantly) correlated with digestion time. The means of seed morphological traits (except for the seed shape index) and germination generally decreased. Germination was negatively correlated with digestion time. Germination of Rumex acetosa, Leontice incerta and Lonicera hispida initially increased and then decreased with increased digestion time, while germination of the other 12 seeds all significantly decreased with increased digestion time. Germination of Plantago depressa, Alyssum desertorum, Lachnoloma lehmannii, Tulipa gesneriana, Tauscheria lasiocarpa and Calligonum rubicundum decreased to zero after 24h digestion, whereas the other nine seeds still had some level of vigour. Seeds of several forbs survived rumen digestion, indicating the potential for endozoochorous seed dispersal, a dispersal mechanism known to enhance survival in dynamic and harsh desert habitats.