Can goats disperse seeds of herbaceous pasture plants in Mediterranean grasslands?

Abstract

In the Mediterranean region, endozoochorous seed dispersal is a potential alternative for the recovery of degraded or abandoned grasslands and shrublands. The objectives of this study were to quantify the number of seeds that pass through the goat gut and to determine whether this process affects seed germination in six common herbaceous species of the Mediterranean area (Ornithopus compressus L., Biserrula pelecinus L., Medicago polymorpha L., Melilotus officinalis L. Pall, Festuca ovina L. and Dactylis glomerata L). We also examined whether the inclusion of the seeds in dung affected seed germination and seedling establishment and growth. The highest seed recovery rate was obtained 24–72h after ingestion. The amount of retrieved seeds varied among species and was generally low, with significant differences among some leguminous and grass species. With the exception of M. officinalis, the quantity of retrieved legume seeds (1.5–6.8%) was greater than that of the grass seeds (0.9–1.1%). A significant relationship was found between recovery of the seeds and their hardness and volume. In all species, the recovered seeds presented significantly lower germinability than seeds that had not been consumed. In general, all recovered legume seeds showed higher average germination rate values (18–50%) compared to recovered grass seeds (0–14%). Seedling emergence was lower in intact than in crumbled dung pellets and, in most cases, the values of both of these were lower than that of unconsumed (control) seeds. No seedling emergence was recorded for seeds of B. pelecinus and O. compressus contained in intact or crumbled faeces at all sampling times. While the percentages of recovery and subsequent emergence found in this study are low in absolute terms, we can conclude that a significant number of seeds may become established from the dung and could be a potential alternative for the recovery of degraded or abandoned grazing areas.