ESTABLISHMENT OF PASTURE SPECIES ON CATTLE DUNG - THE ROLE OF ENDOZOOCHOROUS SEEDS

The process of colonization of cattle dung patches and its relation to endozoochorous dispersal is analysed in a Mediterranean pasture. Dung pats dropped in spring and winter were marked, and the vegetation dev eloping on them during the first two years of colonization was followe d. The influence of endozoochorous seeds on dung colonization is asses sed through the study of: (1) the vegetation on spring and winter dung pats and the seed contents of both, which is abundant in the former a nd negligible in the latter; and (2) the vegetation on spring dung pat s compared with that of the surrounding pasture. The origin of plants growing on dung (either seeds in the manure or in the soil seed bank) was traced by studying dung colonization under controlled conditions i n pots with manure put on seed-free sand, and on pasture turf. The res ults indicate that endozoochorous seeds germinate in manure; they are the main source of recovery in gaps generated by dung pats. The micro- succession involved is independent of the type of pasture. A small-sca le spatial pattern results in which gaps of old dung are dominated by endozoochorous species. Thus, dung patches enhance the similarity betw een grazed communities, and the variation within communities.