Seed banks in an inundation gradient of two grasslands in the 10^th Region (Chile) and their relationship with the plant cover

Abstract

The vegetation and the seed banks of two adjacent grassland communities, a dry one (Hyperico‐Agrostietum) and a humid one (Juncetum proceri), of the 10th Region of Chile were compared. The vegetal cover was estimated in percentage, whereas the density of the seed banks was estimated using two different methods: tray germination in a greenhouse and direct count. In contradiction to the above ground plant cover, the floristic compositions of the seed banks of both grasslands cannot be differentiated by correspondence analysis. Nevertheless all the seed bank samples resemble much more the vegetation of the humid Juncetum proceri grassland, because of the preferential flow of diaspores from the humid grassland towards the dry one. A greater seed density was detected in the humid Juncetum proceri grassland, perhaps due to its greater production of diaspores and due to the fact that high soil humidity retain the seeds longer viable. The germination method displayed a greater efficiency in the detection of seeds, that due to the high amount of small seeds (mainly of Juncus spp.). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)