Seed-bank composition and density of Phumdis (floating islands) in the Keibul Lamjao national park, northeast India

摘要

Keibul Lamjao National Park (KLNP), the only floating national park in the world situated along the south eastern corner of Loktak Lake (the Ramsar Site of International Importance) has been declining over the past two decades due to loss of natural ecosystem. The characteristic feature of the park is the presence of floating organic mass covered with vegetation, soil and organic matter in different stages of decay, locally known as "phumdis". About 135 aquatic and semi-aquatic plant species, including 22 economically important species, grow inside the park (Trisal et al 2002). Acute anthropogenic pressure has been a great concern about the reduction of phumdis and most importantly, the introduction of exotic invasive species. Regeneration of plantspecies of phumdis like other wetland plant communities occurs either by sexual reproduction through seeds or by asexual reproduction through clonal propagation (DeBerry era/ 2000). A plant may employ the former (e. g. annuals), the latter (e. g. submerged aquatics), or both (e. g. herbaceous perennials) as a principal reproductive strategy (Fenner 1985). Although, majority of the plant species associated with phumdis regenerates vegetatively, but information on buried seed bank dynamics and its contribution to the formation of phumdis is still lacking. Therefore, a preliminary study was conducted to investigate the seed bank composition and density of phumdis for future restoration program.