Abstract: In this study, we investigated the influence of pre-fire tree mortality on fire behavior. Although other studies have focused on the environmental factors affecting wildfire, the influence of pre-fire tree mortality has not been explored in detail. We used high-spatial-resolution (1.6 m) airborne multispectral orthoimages to detect and map pre-fire dead trees in a portion of the San Bernardino Mountains, where the ‘Old Fire’ burned in 2003, and assessed whether spatial patterns of fire intensity and burn severity coincide with patterns of tree mortality. Dead trees were mapped through a hybrid deep learning classification and manual editing approach and facilitated with Google Earth Pro historical images. Apparent thermal infrared (TIR) brightness temperature captured during the Old Fire was derived from maximum digital number values from FireMapper airborne thermal infrared imagery (7 m) as a measure of fire intensity. Burn severity was analyzed using normalized burn ratio maps derived from pre- and post-fire Landsat 5 satellite imagery (30 m). Pre-fire dead trees were prevalent with 192 dead trees and 108 live trees per ha, with most dead trees clustered near the northwestern part of the study area east of Lake Arrowhead. The degree of spatial correspondence among dead tree density, fire intensity, and burn severity was analyzed using graphical and statistical analyses. The results revealed a significant but weak spatial association of dead trees with fire intensity (R2 = 0.31) and burn severity (R2 = 0.14). The findings revealed that areas impacted by pre-fire tree mortality were subject to higher fire intensity, followed by severe burn effects, though other biophysical factors also influenced these fire behavior variables. These results contradict a previous study that found no effect of tree mortality on the behavior of the Old Fire.

Keywords: remote sensing; thermal infrared; FireMapper; Sentinel-2; tree mortality; fire intensity; burn severity; southern California; San Bernardino Mountains; Old Fire

Abstract: Green spaces are a significant aspect of a healthy urban environment. Dhaka is losing its greener share for decades. However, a quantitative estimation is needed to evaluate the pattern of changes in green space for proper urban management. This study analyzed green spaces of Dhaka city between 1989 and 2020 (30 years) using GIS and Remote Sensing. 30-meter resolution Landsat satellite images were used for the analysis. Supervised classification was performed to calculate the total change in vegetation and differentiation in healthy and non-healthy green spaces were done using NDVI analysis. Results showed that the total decrease in vegetation of the study area was 56% from 1989 to 2020. However, in 1989 the healthy green space was 17% which decreased to only 2% in 2020. Thus, a severe healthy green space loss was detected (−88.24%). The share of urban land was found to be 82% of the total study area in 2020, which was only 59% in 1989. In conclusion, this study confirms the diminishing state of healthy green space in Dhaka city which is not suitable for a healthy urban environment. It is crucial to properly manage and restore Dhaka city's green spaces and give more consideration to ensure healthy urban area in the future policy making.

Abstract: Urban sprawl is a global phenomenon that has resulted in a substantial impact on ecosystem services. This study assessed how land use changes have affected the ecosystem services in Dhaka and Gazipur districts, two important economic centers of Bangladesh. This study analyzed changes in land use categories and their effects on ecosystem services during a thirty-year period, from 1990 to 2020, using LandSat data and published coefficient values. Additionally, a sensitivity analysis was undertaken to evaluate the ramifications of altering these coefficients on the resultant estimated values. The study revealed that in both Dhaka and Gazipur districts, the expansion of settlement areas and the reduction in tree vegetation cover have led to a significant decline in the overall value of ecosystem services. Over a 30-year timeframe, Gazipur experienced a more substantial loss in tree vegetation cover compared to Dhaka, whereas Dhaka witnessed a greater increase in settlement areas than Gazipur. Remarkably, during the most recent decade (2010–2020), the Gazipur district encountered heightened urban expansion and a more significant reduction in tree vegetation compared to Dhaka. The loss of the entire ecosystem service value was significant, amounting to USD 206.24 million for Dhaka and USD 381.27 million for Gazipur. This loss was primarily attributed to the decline in agricultural land, water bodies, rivers, and a reduction in tree vegetation. The study recommends that a more responsible land-use plan be created to protect tree vegetation, sustainable agriculture, and water bodies, which have the highest ecosystem service value in the study area. Overall, this study highlights the need for sustainable land-use techniques and offers insightful information about how urbanization affects ecosystem services in the investigated areas. 

• PhD - University of Arkansas

Thesis Title - Influence of Anthropogenic Activities and Changes on Niche Shift Across Global Terrestrial Protected Areas

Supervisor - Dr. Brad Peter. Assistant Professor, Department of Geosciences. University of Arkansas.

• MSc - San Diego State University

Thesis Title - Influences of Tree Mortality on Fire Intensity and Burn Severity for a Southern California Forest Using Airborne and Satellite Imagery. 2024 

Supervisor – Dr. Douglas Stow.  Emeritus Distinguished Professor of Geography. San Diego State University.

Co-Supervisor - Dr. Daniel Sousa.  Associate Professor of Geography. San Diego State University

• MSc - Bangladesh University of Professionals) 

Thesis Title - Identification and Characterization of Microplastics in the Sundarbans Mangrove Forest of Bangladesh. 2022

Supervisor – Dr. Md. Mostafizur Rahman. Associate Professor. Jahangirnagar University.

•  (BSc - Bangladesh University of Professionals) 

Thesis Title- Analysis of Urban Green Space Using GIS and Remote Sensing in Dhaka Metropolitan City. 2020

Supervisor – Dr. Md. Mostafizur Rahman, Associate Professor. Jahangirnagar University.