Effect of Flooding Water Level and Plant Density on Growth of Pneumatophore of Avicennia marina.

The height and numbers of pneumatophores of a mangrove, Avicennia marina, were investigated under different levels of plant densities and flooding water level on an experimental stand. Initial plant densities were assigned to four levels, 30, 45, 89, and 260 plants per square meter. After two years and nine months, water levels were changed to keep ground level (control), and 9cm above ground (flooded). The average numbers of pneumatophores per plant under lower plant densities were greater than those under higher densities. Pneumatophores became longer in height and greater in number when the plants were kept under flood. The total numbers and the rate of increment of pneumatophores of the higher density pots under flood well exceeded the numbers of the lower density pots under control. It was concluded that the pneumatophores of A. marina were highly responsive to water level.