Vegetative characteristics of Avicennia marina and Rhizophora mucronata mixed populations in Sirik's Khoor-Azini habitat

Sirik’s Khoor Azini forest stand is one of the most unique mangrove forests in Iran. This forest stand is the only mangrove forest in Iran which is made of two species (Avicennia marina and Rhizophora mucronata) in mixed form so in this case this forest is unique.
Crown dimension of trees is of importance and is determined by measuring crown diameter and height. Measuring these parameters, as characteristics of trees, is useful for comparative comparison in different areas, determining the mean diameter and mean height of the crown, calculating canopy cover percentage, determining the level of correlation with other vegetative factors and correlation of these factors with the environmental conditions of the site. Tree canopy diameter was measured by tape measure in the way that two ends of the tape measure in horizontal mode were perpendicular to an imaginary line tangent to two ends of tree canopy. The crown height was measured the same way as tree height. Crown diameter and height were measured as to cm. Sample plots were selected randomly and the only human intervention in the study area was the movement of some watercrafts within the bay, anyhow the studied forest stands were natural and no management was implemented within them. The density of each stand determined based on the number of all trees per each sample plots and since Avicennia marina trees mostly are in form of coppice in their habitat therefore the density in Avicennia stands was calculated based on coppice groups.
Results of vegetative characteristics measurement in the studied site showed that the mean total height of trees is 1.9 m which is 2.3 and 1.4 m for Avicennia and Rhizophora, respectively. Mean height and canopy diameters of all trees was 1.34 and 1.30 respectively. These parameters were 1.8 and 1.9 m for Avicennia marina and 0.8 and 0.6 m for Rhizophora mucronata. Highest Avicennia marina tree was 6.5 m and highest Rhizophora mucronata tree measured as 4.5 m. Mean percentage of canopy cover was 37.3% that fluctuates between minimum of 25.9% and maximum of 58.4%. The investigation of habitat condition showed that 72.1% of mangrove communities have a density of less than 50%.
Results revealed that mean density is 3600 tree per ha. Also the results indicated domination of Rhizophora mucronata based on the number of trees which was a little more than 50% of all trees per surface unit.