Factors involved in recruitment process of an endemic gypsophyte species in Spain: Teucrium libanitis

Abstract

Gypsum soils in arid and semi-arid environments impose an important restriction of vascular plants. Factors controlling the recruitment of gypsophytes species are not completely understood. Recruitment is the combined result of processes involved in soil seed-bank dynamics and seedling establishment patterns. We examined the spatial and temporal patterns in the recruitment of Teucrium libanitis Schreb. (Labiatae), a gypsophyte endemic to the semi-arid south-eastern Iberian Peninsula, from the perspective of soil seed-bank dynamics. Seed production, soil seed bank, aerial seed bank, seed predation and seedling emergence and survival were monitored for one biological cycle. Different microhabitats were considered in the study to determine safe sites for T. libanitis recruitment. The gypsophyte T. libanitis forms a transient aerial seed bank and a persistent soil seed bank in gypsum steppe with a strategy well-adapted to semi-arid environments. The existence of this persistent soil seed bank supports the theory that the recruitment is produced by the occurrence of favourable climatic events. Seeds were redistributed horizontally, accumulating under plant cover, but seedling survival was not dependent on these different microhabitats. Recruitment was not limited by predation or by seed death by aging and pathogen attack.