Abstract
A field study was conducted to characterise the floristic diversity, biomass productivity and edaphic attributes of the mangrove forests of Puduvyppu (Kerala). We enumerated all trees and shrubs above 10 cm GBH in 50 quadrats (10 m x 10 m), laid out along an east-west transect. Floristic diversity was generally low with only five tree species (Simpson’ Diversity index, D = 0.14). Despite minor variations in floristic composition along the transect, Avicennia officinalis, an early coloniser, dominated the entire area. It also recorded the highest importance value index, density and basal area. Owing to the juvenile nature of the stand, mean biomass productivity was relatively low (47 t ha-1). Two profile pits were dug, one each in the Avicennia and grassland zones, to characterise the edaphic attributes of the site. Horizon-wise variations in physic-chemical properties (pH, EC, total N, available P, K and exchangeable Na) were quite pronounced. In general, the surface horizons recorded higher values. Mineral element concentration was also higher in the Avicennia zone. Both profiles, however, were characterised by a silty clay texture and blocky structure, indicating profound sediment deposition and inundation. Active fluvial dynamics of rivers draining into the adjoin Vemabanadu lake and/or the dredging operations going on in the adjacent cochin bar mouth are perhaps responsible for sediment deposition. Sand pockets, particularly in the lower layers of the grassland profile also provides supporting evidence in this respect.
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