Diameter increments for six mangrove tree species in the sundarbans forest of Bangladesh
1992
Latif, M.A. | Rahman, M.F. | Das, S. | Siddiqi, N.A.
The analyses of the data collected on six occasions in between 1977 and 1990 from the permanent sample plots in the Sundarbans of Bangladesh are presented in the present paper. The diameter at breast height (dbh) increment of the two important species - Sundri (Heritiera fomes Buch. Ham.), and Gewa (Excoecaria agallocha Linn.) were estimated separately for all the site qualities/height classes and salinity zones. The mean dbh increments per year ranged from 0.062 cm to 0.151 cm for sundri and 0.049 cm to 0.189 cm for gewa. There were only a small number of trees for Passur (Xylocarpus mekongensis Pierre), Keora (Sonneratia apetala Buch - Ham), Baen (Avicennia officinalis Linn.) and Kankra (Bruguiera spp.). Therefore, the mean annual dbh increments were estimated for all the site qualities and salinity zones together. The mean dbh increments for passur, keora, baen and kankra were 0.206 cm, 0.192 cm, 0.219 cm and 0.178 cm respectively. The increment rate was higher at higher site qualities and lower salinity zones. But it does not depend on the forest composition. Top dying sundri trees showed lower dbh increment rate. The rate of ingrowth for sundri was 15 trees per hectare per year, while the natural death and removals were 27 trees per hectare per year. The corresponding data for gewa were 22 and 8.1 respectively. The observation suggests that proportion of gewa is increasing and sundri is decreasing. Keora is being eliminated naturally without natural regeneration in the plots.
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