Examining the relationship between land surface temperature and landscape features using spectral indices with Google Earth Engine.

Land surface temperature (LST) is strongly influenced by landscape features as they change the thermal characteristics of the surface greatly. Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Normalized Difference Built-up Index (NDBI), and Normalized Difference Bareness Index (NDBAI) correspond to vegetation cover, water bodies, impervious build-ups, and bare lands, respectively. These indices were utilized to demonstrate the relationship between multiple landscape features and LST using the spectral indices derived from images of Landsat 5 Thematic Mapper (TM), and Landsat 8 Operational Land Imager (OLI) of Sylhet Sadar Upazila (2000-2018). Google Earth Engine (GEE) cloud computing platform was used to filter, process, and analyze trends with logistic regression. LST and other spectral indices were calculated. Changes in LST (2000-2018) range from -6 °C to +4 °C in the study area. Because of higher vegetation cover and reserve forest, the north-eastern part of the study region had the greatest variations in LST. The spectral indices corresponding to landscape features have a considerable explanatory capacity for describing LST scenarios. The correlation of these indices with LST ranges from -0.52 (NDBI) to +0.57 (NDVI).

Phytosociology and biodiversity of roadside herbs in a salinity-affected coastal area of Bangladesh.

Soil salinity in the coastal areas of Bangladesh has been rising. The responses of forest communities to the rise of salinity are somehow documented. However, the adjustments of non-forest plant communities against salinity are still limited in the literature. This study explains the phytosociology and the herbaceous plant biodiversity along with the soil salinity gradients in Shyamnagar, Bangladesh. Twenty-five roadside quadrants were systematically selected and studied for herbaceous plant diversity and soil properties. Soil Electrical conductivity (EC) and moisture show a generally rising trend from the north to the south. Moreover, the quadrants closer to the river or aquaculture with low elevation represent the salinity hot spots. About 1116 herbaceous plants belonging to 11 species were recorded. Croton bonplandianum baill is the dominant species and showed higher adaption capacity against soil EC values. Four out of 25 quadrants with higher EC, moisture and lower elevation recorded no plants. The herbaceous plant biodiversity reveals a strong spatial pattern and tendency to shrink with the rise of soil salinity while progressing towards the southeast direction. The area shows aggregated population, contagious distribution of plant species, and accommodates four dominant clusters. Roadside herbs not only hold medicinal value but also offer important cooking fuel choices to the fuel-scarce coastal communities. The outcome of this study provides important insights into herbaceous plant diversity and its relationships with soil salinity. Overall, the study outcomes improve our understanding of the impact of environmental stressors on the distribution of herbaceous plants in the coastal area.