A Study on the Mangrove Forest Structure at the Koolaghan, Tiyab and Kolahi Regions in the Strait of Hormoz (North Part of Persian Gulf)

Determining the structure of mangrove forests on the basis of the vertical and horizontal stand profiles is considered both as a managing feature and as an approach for utilization or protection. The mangrove forests in the study area at Koolaghan, Tiyab and Kolahi region cover 41,258 hectares and form one of the five mangrove protected areas on the Hormozgan Province shoreline. Hormozgan mangroves are covered by an association of pure and uneven-aged grey mangrove trees (Avicennia marina). The study area is distributed over the area with the latitude 26˚52'50''- 27˚10' 54'' and longitude of 56˚23'37''-56˚ 59' 8''. Four linear transacts were used to determine the structure of the mangrove forests in this area. A quadrate sample plot with 100 m2 in each transect has been used as the measuring unit with random–systematic distribution. In each plot, the height and steed diameter of trees as well as the height and diameter of crowns were measured. Furthermore, 1 m2 micro plots were used to measure the quantity of aerial roots, shed leaves and seedlings. In this way, the growth parameters of 345 trees from 39 sampling plots were studied. The results show that the average intensity of this mangrove stand is 1,014.71 trees per hectare, the average tree height is 190.41 cm and the average stem diameter 10.514 cm. The average heights and diameters oftree's crowns were measured at 151.74 cm and 230.74 cm, respectively. In a like manner, the average area of crown was calculated at 6.01 m2. The number of aerial breathing roots was established as 197.50 per cubic meter with an average height of 11.24 cm. The number of leaves shed on the forest floor was 119.34 per cubic meter with an average area equal to 6.95cm2. Statistical studies showed that plots of the Koolaghan region are homogeneous, nevertheless there are significant differences in other sampling plots among the transects of some parameters such as tree height, crown height, crown diameter, crown area and stem diameter, with a 95% certainty. However, we couldnt find any difference in some parameters such as tree density and coverage percentage, so all the areas studied were homogeneous in these parameters.