Figueira, J.E.C., Santos, F.A.M. & Brito, R.F. 1998. Fire, competition and semelparity in Paepalanthus polyanthus (Eriocaulaceae) from Brazil. Proceedings of the VII International Congress of Ecology, Florence, Itália, p.136. Abstract: Semelparous plants with great longevity are uncommon in nature. This was described at least for 20 plant families, but apparently never for Eriocaulaceae. Paepalanthus polyanthus is a caulescent rosette plant that occurs in high elevation fields of the Serra do Cipó (SE Brazil). The estimated age of plants 1m in height, is 30 years. Its inflorescences are composed and born from the apical meristem. Most of the individuals die before reproducing. Nevertheless fires induce mass flowering. In spite of this unpredictability, fires can make the environment more favorable to seedling establishment, eliminating the dense grass cover and liberating nutrients to the soil. Thus, fires could have favored the evolution of semelparity linked to great longevity. Individuals should survive for long periods of time until the occurrence of a fire. At this time, a single and concentrated reproduction effort would be advantageous. P. polyanthus occurs in well defined soil patches, suggesting specific requirements to seed germination and survival and seedling development. On the other hand, this well defined distribution should be a consequence of the limited dispersion of seeds, which lack special structures for long distance dispersion, generating high local densities and restricting its spatial distribution. Semelparity in P. polyanthus can be a strategy to reduce competition for water, nutrients and space. After the death and decomposition of the parental plant, nutrients would return slowly to the soil, to reduce competition for water, nutrients and space. After the death and decomposition of the parent plant, nutrients would return slowly to the soil, becoming available for the development of their seedlings. This would be advantageous specially in poor and dry soils where this plant occurs. |