articles by Anwarul Islam Chowdhury
European Journal of Forest Research , 2022
Natural regeneration and forest successional development are influenced by gap formation in fores... more Natural regeneration and forest successional development are influenced by gap formation in forest stands. Nonetheless, there are limited studies that provide quantitative information on the influence of gaps on forest regeneration. We evaluated characteristics of inner and outer canopy gaps and their effects on natural regeneration in 40 canopy gaps in Sitapahar forest reserve of Bangladesh. A total of 50 individuals of 27 gapmaker tree species were found, of which 58% were formed by logging and the rest by natural damages. Elliptical shape represented 53% of the gaps followed by circular and rectangular gaps. The mean area of the outer and inner gaps was 50.1 ± 8.6 and 20.0 ± 3.0 m2, respectively. Gap formation types and shapes did not vary significantly between outer and inner gaps, while the mean gap area in older gaps was significantly higher than in new gaps. In comparison with outer gaps, mean densities of seedlings and saplings in the inner gaps were significantly higher, which is probably because of the closeness to seed trees. The diversity index of regenerating species and their height and collar diameter did not vary significantly between the inner and outer gaps. Positive, but weak relationships of gap area with subcanopy tree density and diversity were found. Since gaps were found dominated by few light-demanding tree species such as Brownlowia elata, Lithocarpus acuminata, Lithocarpus polystachya, and Macaranga denticulate, it is suggested that larger gaps need to be replanted with a combination of light-demanding and shade-tolerant native trees.
Journal of Cleaner Production, 2022
Urban trees have capacity to reduce atmospheric particulate matters (PM) concentration through de... more Urban trees have capacity to reduce atmospheric particulate matters (PM) concentration through deposition on leaves. However, we have very limited studies on the contribution of urban trees toward removal of PM in Bangladesh. In this study, conducted in Chattogram City Corporation (CCC), Bangladesh, we aimed to i) quantify the ambient atmospheric PM (PM2.5 and PM0.50), ii) quantify deposition of PM by urban trees, and iii) find out variation of PM with respect to common tree species, height of trees (low: 2.0–3.5 m and mid: 3.5–4.5 m), leaf traits (shape, surface), and seasons. Monthly air PM concentrations were measured from September 2020 to April 2021 in six sites (viz. roadside, residential, industrial, commercial, medical, and park area) in CCC. For measuring PM deposition, we collected 128 sample leaves from eight randomly selected trees of eight tree species in every month from study sites. At roadside, where relative greenspace was lowest, the atmospheric PM concentration was the highest. Conversely, where relative greenspace was higher (e. g. residence and park), the PM concentration was the lowest. In winter season (December–February), both ambient PM concentrations and deposition on leaves were the highest. Psidium guajava had significantly (p < 0.05) higher PM deposition than other tree species at both height levels. Deposition of PM was highest in trees with oblong and ovate-shaped, and rough-surfaced leaves at lower height, and therefore, recommendation is made to plant trees with these attributes in urban areas.
Rhizosphere, 2023
The consequences of converting primary forests to agriculture and pasture on soil carbon (C) and ... more The consequences of converting primary forests to agriculture and pasture on soil carbon (C) and nutrient stocks are important, although they are little known in tropical forests. In the Sitapahar forest of Bangladesh, we evaluated soil C and nutrient concentrations and stocks among intact, fragmented, and shifting cultivation sites. We also investigated whether there are any correlations between nutrient stocks and tree species diversity or soil C stock. We measured and identified the trees in 30 main plots (20 m × 20 m), 10 in each of the three sites. Four subplots (1 m × 1 m each) were used to measure the physical and chemical characteristics of the soil at depths of 0–10, 10–20, and 20–30 cm. Results show that during shifting cultivation as compared to intact sites, soil C stock was 50% lower whereas soil P stock was 26% greater. When compared to the other two sites, the soil N and K stocks under the shifting cultivation site were 57% and 27% greater, respectively. Soil Mg stock in the intact site was up to 155% higher compared to the other two sites. In all sites, soil C stock was positively correlated with N stock, but negatively correlated with the P stock. Tree species diversity was positively correlated with K stock, but negatively correlated with N stock in the shifting cultivation site. Sustainable management of the sites should focus on the understanding of soil-plant interactions and the protection of soil C, nutrients, and species diversity.
Tropical forests play a significant role in sequestrating and storing atmospheric carbon di-oxide... more Tropical forests play a significant role in sequestrating and storing atmospheric carbon di-oxide (CO2) emissions. However, estimation of forest carbon (C) stocks in relation to changes in forest structure and disturbances are less studied. We estimated forest C stocks in live trees, saplings, lianas, deadwood, forest floor, and soil in Sitapahar natural forest reserve of Bangladesh based on field measurements and laboratory assessments. We categorized the 99 temporary sample plots into three canopy densities: closed, moderately closed, and open. According to the results, the forest C stocks were dominated by the soil C pool and forest C stocks in the closed canopy (91 Mg ha−1) differed significantly from that in the open canopy (50 Mg ha−1). Forest C stocks were also affected by basal area (BA) and deadwood C stocks. In the open canopy, the second highest contributor to forest C stock was deadwood, whereas it was above and below-ground live biomass in the closed and moderately closed canopies. In the open canopy, forest disturbances significantly decreased height and BA, and C stocks in live biomass were significantly lower compared to the other two canopy densities. In the open canopy, decreased tree density resulted in the lowest C stock in litterfall and humus, and they were up to 95% lower compared to the other two canopy densities. C stocks in humus were higher than those in litterfall in the closed and moderately closed canopies, which was opposite to that in the open canopy. The soil C stock decreased with soil depth and the highest C stocks across all depths were in the closed canopy, followed by the moderately closed and open canopy. This study also provided a stand-level estimation of C stocks that contribute to determining which tree species sequester more carbon, such as Swintonia floribunda, Lannea coromandelica, Anacardiaceae and Moraceae.
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articles by Anwarul Islam Chowdhury