In the present study, the experimental plots were laid out in Randomized Complete Block Design (RCBD) method; three size classes were considered to count regeneration in the laid temporary sample plots. In each of the six locations, three quadrants were laid out and thus a total of 18 Temporary Sample Plots (TSP) were established to assess the vegetation and regeneration composition of the major mangrove species with a view to evaluating the stand density in the forest. Each TSP plot covered an area of 2.5m x 4m = 10m2.
Study Sites are Kalabogi – in the compartment no. 32 , Bojboja- compartment no. 37, Baniakhali- compartment no. 35, Kashiabad- compartment no. 36, Chunkuri- compartment no. 47, Supati- compartment no. 4, of the Sundarbans. All the seedling, saplings and trees were enumerated and recorded from the three sub plots according to size classes of seedlings.
Observation of Symptoms of Heart Rot Disease of Passur
In each location, a total of 100 Passur trees were randomly selected for observing symptoms of heart rot disease. The symptoms of heart rot disease have been observed and recorded from time to time in the Sundarbans following Randomized Complete Block Design (RCBD). Disease affected and healthy trees were also recorded. In addition, the data on diameter at breast height (dbh, 1.3m) were recorded by Dia Tape in all the study sites from the selected trees.
Categorization of Heart Rot infested Passur Trees
In this study, the experimental plots were laid out in Randomized Complete Block Design (RCBD) in the six locations. In each location, one quadrate was laid out to observe the incidence of heart rot of Passur trees along with healthy (Unaffected) trees. The data of percent heart rot of Passur in four dbh classes from Kalabogi, Bojboja, Baniakhali, Kashiabad, Chunkuri and Supati are also provided for much easier comprehension. The study was conducted during October 2007 t0 December,2012.
Canopy Class Description of Passur in the Study Site were noted G1 canopy tree class, G2 canopy tree class, G3 canopy tree class, and G4 canopy tree class
Data was tabulated, G1 was considered as healthy tree and G2, G3 and G4 were considered as heart rot affected trees. Diameter at breast height (dbh, 1.3m.) of the trees was also recorded. Four dbh classes were considered to measure the observation following Karim (1995). The dbh classes were CI (<20cm), C2 (21-30cm), C3 (31-40cm) and C4 (>40cm). Collection of Fungal Fruit Bodies from Heart Rot disease affected Passur Trees were tested and identified in the laboratory systematically. Identification of Fungal Disease in the Pathological Laboratory were done in the laboratory systematically. Disease Symptoms were observed in the field conditions.