Hypersalinity and Low Nitrogen Levels Cause Dwarf Growth in Mangrove Avicennia marina (Forssk.) Vierh.

Mangrove productivity in the coastal regions mainly depends on the tidal influx, which supplies essential nutrients. Less tidal exposure and reduced water uptake levels can severely affect mangrove growth. In this context, we identified two distinct mangrove zones of Avicennia marina (Forssk.) Vierh., at a remote geographical zone, southeast coast of India. The first zone comprised profuse growth, and the second inhibited tree growth. A. marina trees grown in the first zone has more tidal flush exposure; thus, tree growth rates in this zone were higher. Whereas zone 2 is not at all exposed to tidal flush but has limited or no water exposure, thus trees grown in this zone displayed dwarfing or inhibited growth. Relatively, trees in zone 2 possess reduced height and length as well as the reduced height of aerial roots. Nutrient analysis of sediment samples revealed that deficiency of total nitrogen (727.93 µM L −1 ) and high concentration of total phosphorus (126.92 µM L −1 ) contents in zone 2 than zone 1 are the root cause of dwarf growth of A. marina . The present study infers that restricted tidal flow, water scarcity, and limited water exposure can prominently inhibit A. marina growth.