Close up of right side of figure 3. A satellite image covered in red, green, and yellow highlights

Assessing Human-Driven Forest Land Conversion in Bangladesh: Insights from Tropical Moist Deciduous Forests

Kazi Nazrul Islam

Abstract 

Bangladesh, a densely populated South Asian country, has approximately 12% forest cover and hosts a variety of tropical forest ecosystems, including tropical evergreen forests, tropical moist deciduous forests, tidal mangrove forests, and coastal plantations. Among these, the tropical moist deciduous forest—locally known as the Sal Forest—is geographically located in the central plains near the capital city, Dhaka, and is dominated by Shorea robusta Gaertn. f. (locally known as Sal). This forest ecosystem has long faced significant anthropogenic pressures, leading to degradation from illegal logging, overgrazing, fuelwood collection, and poaching, as well as forest conversion due to illegal encroachment, agricultural expansion, urbanization, and plantations. This study analyzed land conversion in the Sal Forest ecosystem from 1995 to 2025, focusing on the transition of forest areas to non-forestry land uses. Landsat 5 and Landsat 9 satellite imagery were used to detect spatiotemporal changes in land use across the Sal Forest landscape. Supervised classification techniques were applied using Maximum Likelihood (ML) and Minimum Distance Error (MDE) algorithms, and accuracy was evaluated using a confusion matrix. The results showed a substantial decline in natural Sal Forest cover, primarily replaced by agriculture, agroforestry, urban development, and settlements over the three-decade period. Accuracy assessment indicated that the ML algorithm performed better with Landsat 9 imagery, while MDE yielded higher accuracy for Landsat 5. The findings offer critical insights for policymakers to guide conservation planning and restoration strategies, emphasizing the spatial patterns of forest degradation and land use transformation in this vulnerable ecosystem.

Map of tropical moist deciduous forests in Bangladesh, including madhupur national park, bhawal national park, tangali Division, and dhaka division

Figure 1: Distribution of Sal Forests in Bangladesh

Landsat 9 2025 on left, much greener than landsat 5 1995 on right, much browner

Figure 2: Downloaded images of the study site.

Side by side comparison of sal forest landscape 1995 on left and 2025 right, with an increase in Urban and agricultural settlements, especially in the southeastern section.

Figure 3: Land use map of Sal Forest landscape in 1995, 2025

bar graph of land use changes in Sal Forest comparing 1995 and 2025, showing the overall increase in agriculture and agroforestry, urban and settlement, and a slight decrease in sal and a large decrease in plantations.

Figure 4: Temporal changes in different land uses in Sal Forest landscapes during 1995 to 2025

Table providing an overview of all Landsat missions along with their key features

Table 1: A brief history of Landsat mission (adapted from LANDSAT, 2025).

Table that provides a summary of recent studies that have utilized Landsat data specifically for forest management applications.

Table 2: Landsat product assisted recent scientific studies in the field of forest management.

Table of area of each land use in 1995 and 2025

Table 3: Transition matrix.

Table of overall accuracy and kappa coefficient for data from 1995 and 2025

Table 4: Accuracy assessment and Kappa statistics.