Relationship between Elemental Concentrations and Top-Dying Disease in Mangrove Forest Trees in the Sundarbans in Bangladesh
Issue:
Volume 2, Issue 4, July 2014
Pages:
41-53
Received:
1 June 2014
Accepted:
13 June 2014
Published:
30 June 2014
Abstract: The present work has explored some of the possible environmental factors involved, focussing particularly on the relationship between the amount of top-dying in different places and the concentrations of a number of chemical elements present in the soil, in order to test the hypothesis that chemical pollution might be responsible. Nine plots were selected for sampling of soil, and from these plots 63 soil samples were assessed, mainly by ICPMS, to investigate certain parameters of the soil, such as Sn, Exchangeable K, Pb, Zn, Sc, and elemental concentrations of 32 other elements. Most of the elements studied had no significant correlation with the top dying of Heritiera fomes. Survey was done to categorize different areas in terms of their intensity of top-dying within the study area in Sundarbans (the largest single tract of mangrove forest in the world). The vegetation structure was assessed in terms of tree height, bole diameter, species present, and regeneration status; and the intensity of top-dying within the plots was recorded on a rank scale basis such as trees which are not affected by top dying disease(rank-0),commonly affected by top dying disease(rank-1), moderately affected by top-dying disease (rank-2) and severely affected by top dying disease(rank-3) based on relevant maps, documents, literature, consultations with forest professionals, and surrounding peoples. This was later expressed as a semi-quantitative or rank scale of 0 to 3 respectively, so that a median rank value could be calculated and used as an index of top-dying intensity in that plot. After that, the total number of seedlings (individuals of the tree species <1 m tall), and saplings (young trees >1 m tall with a diameter of trunk of < 10 cm), were counted within the plots. However, Sn, Exchangeable K, namely Pb, Zn, Sc, were also close to significance. Sn concentration is negatively associated with top dying. Exchangeable K was positively associated with the tree diameter whether the top dying was severe or mild. However, the present results have showed that Sn, Exchangeable K, Pb , Sr and Zn and could be directly linked with top-dying of Heritiera fomes (Sundri) in Sundarbans, probably particularly by weakening the vigour of the trees and allowing other factors such as pathological agents to attack the plants.
Abstract: The present work has explored some of the possible environmental factors involved, focussing particularly on the relationship between the amount of top-dying in different places and the concentrations of a number of chemical elements present in the soil, in order to test the hypothesis that chemical pollution might be responsible. Nine plots were s...
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