An experimental test of the role of micro-spatial heterogeneity in the co-existence of congeneric plants

A field experiment is reported in which differential survival of seeds and seedlings in response to fine-scale heterogeneity is tested as a possible mechanism of plant co-existence in species-rich plant communities. Eight hundred seeds each of three pairs of congeneric species were sown into grassland micro-sites with variable amounts of leaf cover and their fate determined by weekly censuses over a three month period. Seeds of Leontodon spp. and Plantago spp. germinated significantly better in micro-sites with low leaf cover but difference between species in the same genus were not apparent. Differential seeding survival of two Centaurea species was observed and a transitory difference in seedling survival between Leontodon species in different micro-sites was also observed.