PARENT SESSION
Contributed Oral Session 83: Human Impacts on Coastal Areas
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
Soil physico-chemical factors contribute to dwarfing in the mangrove, Avicennia marina.
Naidoo, Gonasageran *,1, 1 University of KwaZulu-Natal, Durban, KwaZulu-Natal, South africa
ABSTRACT- In this investigation we compared soil physico-chemical conditions, water and ion relations and photosynthetic performance of fringe and dwarf Avicennia marina in Richards Bay, South Africa. We hypothesized that soil physico-chemical factors contributed to dwarfing in Avicennia marina. In the dwarf site, soil salinity, electrical conductivity and soil concentrations of Na+, K +, Ca2+, Mg2+, Zn2+, Mn 2+, and Cu2+ were significantly higher than in the fringe zone. Soil water potential and the concentration of soil P, however, were significantly lower in the dwarf site.In the leaves, Na+ was the predominant ion, and its concentration was higher in dwarf than in fringe mangroves. Leaf concentrations of K +, Ca2+, Mg2+, Mn 2+ and P, however, were significantly lower in the dwarf mangroves. Photosynthetic performance, measured by gas exchange and chlorophyll fluorescence, was significantly reduced in the dwarf plants. The results suggested that high soil salinities, low soil water potential and P limitation contributed to dwarfing in A.marina.
Key words: A.marina, hypersalinity, dwarfing, mangrove