Abstract:
This research was conducted with the objective of estimating Above Ground Biomass (AGB)
using Geographical Information Systems (GIS) and Remote Sensing (RS) technology and analysing
the impact of its variation, based on the core research problem of the increase in associated
Land Surface Temperature (LST) due to the decrease in AGB in Kirala Kale Sanctuary in the
Matara District, Sri Lanka. Landsat data were used as secondary data, while primary data were
collected through field measurements (DBH), location mapping and interviews. The Kirala
Kale Sanctuary is a wetland ecosystem covering an area of 337.32 hectares. Using satellite data
and ArcGIS 10.8 software, Normalised Difference Vegetation Index (NDVI) was calculated for
the years 1996, 2006, 2016 and 2024, and then AGB was estimated using an allometric equation.
The AGB data derived from satellite imagery were validated through field measurements,
revealing a significant positive correlation. According to the study results, the average value of
AGB in 1996 was 19.17 Ton/ha, and it had decreased to 18.25 Ton/ha in 2006. It was emphasised
that AGB has decreased by as much as 13.9 Ton/ha in 2016 and AGB has decreased to
13.634 Ton/ha in 2024. AGB has decreased by 9.5% during the period 1996 - 2024, and the
increase in LST can be identified as the strongest impact. The temperature in the study area,
which was 25.07°C in 1996, has increased to 30.14°C in 2024. Correlation analysis between
AGB and LST revealed a negative correlation. In the main affected area, Matara city, an increase
in maximum temperature from 31.16°C in 1996 to 32.96°C in 2024 can be detected. As
a final conclusion, the effect of AGB reduction on the increase in LST is emphasised.
