3.1.1 Climate of Dhaka There is a hot, wet and humid tropical climate in Dhaka city as well as Dhaka North City Corporation. The city has a monsoonal season, with and annual average temperature of 260C and monthly mean varying between 190C in January and 290C in May (Weatherbase, 2008). The daily average maximum temperature in Dhaka city is 250C in January with the average of minimum 100C, while in the June the average maximum temperature is 320C with a minimum of 250C. The wettest month in Dhaka is July with an average rainfall of 367.9 mm while the driest month is December with 809 mm precipitation. The climate data were collected from secondary sources.
3.1.2 Geographical location and other factors of study area The study was carried out in the Dhaka North City Corporation (DNCC) and it has located between 23º44-23º54 'N latitude and 90º20-90º28 'E longitudes respectively (Wikipedia, 2011). Dhaka North City Corporation (DNCC) is one of the two municipal corporations in Dhaka created when the former Dhaka City Corporation was divided. Dhaka North City Corporation is a populated area. It has covered 82.638 square kilometer area and consists of 36 number of wards covering the thanas Dhaka North City Corporation consists of 36 wards covering the thanas of Mirpur, Mohammadpur, Sher-E-Bangla Nagar, Pallabi, Adabor, Kafrul, Dhaka Cantonment, Tejgaon, Gulshan, Rampura, Banani, Khilkhet, Vatara, Turag, Badda, Uttara, Uttarkhan, Dakkshinkhan & some others. It has 28 parks, 15 playgrounds, 3 gardens graveyards 06 etc. It has also consists of 1337.913 km roads and 223.049 km footpath which also help to make a urban forest structure through street tree species (Ibrahim, 2014).
3.1.3 Soil According to the geological origin of soils; Dhaka city is under the category of Modhupur soil tract (AEZ 28) which consists mainly of silt and clay (FAO & UNDP, 1998). Soil of the experimental site mainly belongs to the medium high land and its texture contains silty loam, olive-gray with common fine to medium distinct dark yellowish brown mottles with a pH 5.6 (UNDP & FAO, 1998).
3.2.1 Selection of Sampling Area Reconnaissance survey was made to the study area in order to get general information about the vegetation, and accessibility to the parks and other green spaces and a list of all tree species was prepared for further data collection. For conducting the survey the whole DNCC was divided into three categories according to its vegetation characteristics named: 1. Parks 2. Gardens and 3. Roadsides.
3.3.2 Plant Species Sampling A total of 40 sample plots (Chandrima Uddan, Botanical Garden, Rokeya Sarani, Mirpur-2 Road and Zoo Road) were taken from the three categories of habitats. All trees in each quadrate were recorded and the number of each tree species was quantified. The common species were identified directly in the field. A list of species was made with scientific name and family found in the sampling area. The species will be categorized into 3 categories. They are: 1) Tree layer: the tree species which are more than 1.5 meter in height. 2) Shrub layer: Tree species which are less than/equal to 1.5 meter in height. 3) Herb Layer: species which are less than/equal to 1 meter in height.
3.3.4 Data analysis After finishing the collection of field data, all the data was organized and analyzed by using MS Excel, and SPSS software. The density (stem/ha), frequency (%), relative frequency (%), basal area (m²/ha), relative dominance and Importance Value Index (IVI) were calculated following the formulas of Moore and Chapman (1986), Shukla and Chandel (1980) and Dallmeier et al. (1992) for quantitative structure and composition for each trees and shrubs species.