Abstract:
In the current context of increasing urbanization and a related increase in
greenhouse gas emissions, rooftop gardens are alternatives means in mitigating
climate by its potential Carbon (C) sink. This work was aimed at estimating the
aboveground carbon stock and tree diversity in the areas of DAE projected four
metropolitans viz. Mirpur, Mohammadpur, Gulshan and Tejgaon of Dhaka city. The
data of 63 rooftop gardens were analyzed; a total of 883 trees were sampled and 32
different tree species under 21 families were identified and recorded on the basis of
tree diversity and Carbon stock. It was found that large rooftop gardens had 31
different types of species where mean number of trees per hectare was 586.97,
medium rooftop gardens had 29 different types of species where mean number of
trees per hectare was 616.86 and small rooftop gardens had 16 different types of
tree species where mean number of trees per hectare was 701.45. The Shannon
Wiener index was used to assess the tree diversity per rooftop garden and it ranged
from 1.45 to 3.79 with a mean value of 2.74. The carbon estimations were done
using allometric equations for small sized trees with diameter at breast height
(DBH) as predictor variable for biomass. Size of the tree, diameter at breast height
(DBH) and tree species diversity data were analyzed. As the few samples of the
monitored population was smaller than 1.3 m and destructive measurements was not
possible, root collar diameter (RCD) was recorded and corrected to be used in the
allometric model. Among the rooftop garden categories large area gardens had the
highest carbon stock 3.071 Mg ha
-1
(ranges from 1.65 Mg ha
-1
to 4.66 Mg ha
) and
lowest carbon stock 1.867 Mg ha
-1
was found in small rooftop gardens (ranges from
1.18 Mg ha
-1
to 2.83 Mg ha
-1
). Among the five major dominating species the highest
amount of carbon was stored by Mango (20.37 Mg) followed by Guava (16.84 Mg),
Jujube (13.84 Mg), Sapota (12.34 Mg) and Carambola (11.32 Mg). The results of
the study show that rooftop farming of Dhaka city has a diverse tree species that
could contribute significantly by reducing carbon in the atmosphere.
Description:
A Thesis
Submitted to the Faculty of Agriculture,
Sher-e-Bangla Agricultural University, Dhaka
in partial fulfilment of the requirements
for the degree of
MASTER OF SCIENCE
IN
AGROFORESTRY & ENVIRONMENTAL SCIENCE