Vegetational changes in the coral-gravelly barrier spit appearing after the 2004 Indian Ocean Tsunami at Pakarang Cape, southwestern Thailand, related to topographical changes

Abstract

Vegetational change was studied during 2010-2015 in the coral-gravelly barrier spit that appeared in 2007 in association with the 2004 Indian Ocean Tsunami at Pakarang Cape, southwestern Thailand, related to topographical changes. No lichens, liverworts, or ferns were found during the study period, although lithophytic algae were widespread over the coral gravel. Several woody species, along with several creeping herbaceous species, colonized the area soon after appearance of the barrier spit. Coral gravel covering the ground surface prevented the sand movement, facilitating colonization by drifting seeds. In all, 37 species of vascular plants, comprising 21 woody and 16 herbaceous species, were recorded through 2015. Annual monitoring of the plant covered area, location, and height of all the trees taller than 20 cm along with formation process of the barrier split using highresolution GPS revealed that vegetation was affected strongly by topographical changes. In accordance with easterly movement of the barrier spit, vegetation largely disappeared in the western part, although it developed in the eastern part. Casuarina equisetifolia increased and grew significantly faster than other species, producing a thick forest in the stable central part of the barrier spit during the study period.