Xylem hydraulic adjustment to global climatic changes was reported from temperate, boreal, and Mediterranean tree species. Yet, the long-term hydraulic adjustment in tropical tree species has not ...been studied so far. Here we developed the first standard chronologies of three hydraulic trait variables for three South Asian moist forest tree species to analyze their long-term hydraulic responses to changing climate. Based on wood anatomical measurements, we calculated Hagen-Poiseuille hydraulically weighted vessel diameter (D
), potential specific hydraulic conductivity (K
), and vulnerability index (V
) and developed standard chronologies of these variables for
, and
which are different in their xylem structure, wood density, shade tolerance, growth rates, and habitat preferences. Bootstrap correlation analysis revealed that vapor pressure deficit (VPD) strongly positively influenced the xylem water transport capacity in
, whereas
was affected by both temperature and precipitation. The hydraulic conductivity of
was mainly affected by temperature. Different adjustment strategies were observed among the species, probably due to the differences in life history strategies and xylem properties. No positive relationship of conductivity and radial growth was found, but a trade-off between hydraulic safety and efficiency was observed in all studied species.
We performed a global analysis with data from 149 countries to test whether temperature can explain the spatial variability of the spread rate and mortality of COVID-19 at the global scale. We ...performed partial correlation analysis and linear mixed effect modelling to evaluate the association of the spread rate and motility of COVID-19 with maximum, minimum, average temperatures and diurnal temperature variation (difference between daytime maximum and night-time minimum temperature) and other environmental and socio-economic parameters. After controlling the effect of the duration since the first positive case, partial correlation analysis revealed that temperature was not related with the spatial variability of the spread rate of COVID-19 at the global scale. Mortality was negatively related with temperature in the countries with high-income economies. In contrast, diurnal temperature variation was significantly and positively correlated with mortality in the low- and middle-income countries. Taking the country heterogeneity into account, mixed effect modelling revealed that inclusion of temperature as a fixed factor in the model significantly improved model skill predicting mortality in the low- and middle-income countries. Our analysis suggests that warm climate may reduce the mortality rate in high-income economies, but in low- and middle-income countries, high diurnal temperature variation may increase the mortality risk.
Efficient water transport through xylem determines tree performance particularly when trees are under water stress. Yet, the hydraulic behaviour of the tropical moist forest of Bangladesh has not ...been adequately understood. The aim of this study was to evaluate the hydraulic conductivity and hydraulic vulnerability of tree species from a nature reserve of Bangladesh (The Rema-Kalenga Wildlife Sanctuary, RKWS) and to assess their relationship with tree size, wood anatomical and leaf stomatal traits. Increment cores and leaf samples were collected from a total of 325 individual trees representing 56 species distributed in 55 randomly selected sampling plots. Following a standard protocol, xylem anatomical parameters such as vessel radial diameter (RD), vessel tangential diameter (TD), and vessel density (VD) were measured. Stomatal density (SD) and stomatal guard cell length (SGCL) were measured using the light microscope from the abaxial surfaces of leaves. Potential hydraulic conductivity (Kp) and vulnerability index (Vx) were determined from the vessel measurements. Demographic variables were measured directly in the field. Results showed that both Kp and Vx varied among the species. We found a significant differences in Kp (F=11.695, P < 0.001) and Vx (F=3.6045, P < 0.05) among the trees of different phenological groups- deciduous, evergreen, and brevi-deciduous. The independent sample t-test showed a significantly higher Vx in light demanding species than in shade tolerant species (t = 3.85, p < 0.001). However, there was no significant difference in (Kp) between species group with different shade tolerance which is consistent with the results derived from nested ANOVA testing the relative importance of each functional group. Kp was positively related with SD, crown surface area (CSA), tree height, and DBH and negatively related with wood density (WD). However, we interpret the Kp-WD relationship with caution since a few species with low density had more influence on this relationship. Our study demonstrates that plant functional type is an important factor in regulating hydraulic efficiency and safety in moist tropical forests.
•Hydraulic traits, xylem vessel traits, and stomatal traits were measured in a moist tropical forest.•Significant differences in hydraulic traits were observed among different functional groups.•Stomatal density, wood density, tree size and leaf traits influenced hydraulic function in moist tropical forest.•Coordination of hydraulic functions with various factors varied with leaf phenology and species light requirements.
Tree growth in the tropics is strongly influenced by climate. However, reported tree growth responses to climate are largely inconsistent, varying with geographic location, forest type, and tree ...species. It is thus important to study the growth responses of tropical trees in sites and species that are under-represented so far. Bangladesh, a country influenced by the Asian monsoon climate, is understudied in terms of tree growth response to climate. In the present study, we developed a 121-year-long regional ring-width index chronology of Chukrasia tabularis A. Juss. sampled in two moist forest sites in Bangladesh to investigate tree growth responses to climate in monsoon South Asia. Standard dendrochronological methods were used to produce the ring-width chronologies. The climate sensitivity of C. tabularis was assessed through bootstrap correlation analysis and the stationarity and consistency of climate–growth relationships was evaluated using moving correlation functions and comparing the regression slopes of two sub-periods (1950–1985 and 1986–2015). Tree growth was negatively correlated with the mean, minimum, and maximum temperatures, particularly during the early growing season (March). Likewise, precipitation negatively influenced tree growth in the later growing season (October). Besides, radial growth of Chukrasia sharply ceased in years following strong and moderate El Niño events. In parallel with a significant positive trend in local temperatures, tree growth sensitivity to early growing season (March–April) mean temperatures and July minimum temperatures increased in recent decades. Tree growth sensitivity to October precipitation and April vapor pressure deficit also increased. Overall, climate–growth relationships were stronger during the period 1986–2015 than during 1950–1985. Changes in climate sensitivity might be linked to a warming trend that induced an increase in the dry season length during recent decades. With a further predicted temperature increase at our study sites, our results suggest that radial growth of C. tabularis will further decline in response to climate warming.
Background and Aim: Slaughterhouses act as a significant public health hotspot in developing countries like Bangladesh. The study aimed to investigate small ruminants at slaughterhouses for ...pathological study and molecular detection of important zoonotic diseases.
Materials and Methods: A total of 75 goats and 14 sheep were investigated from June 2019 to January 2020 at different slaughterhouses in Mymensingh division, Bangladesh. The targeted diseases were tuberculosis (TB), listeriosis, Q fever, brucellosis, anthrax, toxoplasmosis, hydatidosis, and linguatulosis. The tentative diagnosis was made based on gross and histopathological lesions. Polymerase chain reaction (PCR) was performed to confirm the causal agents of zoonotic diseases using disease-specific primers.
Results: Grossly, caseous nodule formation in the visceral organs; enlarged and calcifications of mesenteric lymph nodes (MLNs); hydatid cyst formation in the liver were the predominant lesions observed. Histopathologically, granuloma, caseous necrosis, and calcifications admixed with acid-fast bacteria in the MLNs, liver, spleen, and kidney were seen as suggestive of infectivity due to TB. Septic lymphadenitis mixed with rod-shaped bacteria, doughnut granuloma, fibroplasia accompanied by eosinophils and lymphocytic infiltration in MLNs, and portal granuloma were observed in listeriosis, Q fever, linguatulosis, and toxoplasmosis suspected cases, respectively. The PCR amplified Mycobacterium tuberculosis complex (372 bp), Mycobacterium bovis (600 bp), Listeria monocytogenes (517 bp), Toxoplasma gondii (512 bp), and Coxiella burnetii (687 bp) species-specific amplicons. In addition, linguatulosis and hydatidosis were identified in six and three goats, respectively. Brucellosis and anthrax were not detected in any cases. The slaughterhouse samples were also found to harbor the coexistence of different zoonotic pathogens.
Conclusion: Deadly infectious zoonotic diseases in goats and sheep at slaughterhouses may cause widespread public health risks. As a result, more intensive monitoring and epidemiological surveys are required to successfully prevent and control zoonotic diseases.
Critical Review of Lead Pollution in Bangladesh Majumder, Ahmad Kamruzzaman; Al Nayeem, Abdullah; Islam, Mahmuda ...
Journal of health & pollution,
09/2021, Letnik:
11, Številka:
31
Journal Article
Recenzirano
Odprti dostop
Lead (Pb) poses a severe threat to human health and the environment. Worldwide Pb production and consumption have significantly increased along with unplanned industrialization and urbanization, lead ...smelting, and lead-acid battery processing. The improper management of Pb-containing elements is responsible for Pb pollution. Lead's persistence in nature and bioaccumulation in the food chain can lead to adverse health impacts.
The present study aims to describe Pb contaminated sites in Bangladesh and Pb concentration in the atmosphere, water, sediments, soil, vegetables, fish, and other foods in Bangladesh.
The present study searched a total of 128 peer-reviewed articles based on a predefined set of criteria (keywords, peer-reviewed journals, and indexing in Scopus, Science Direct, Web of Science, Springer, PubMed, Directory of Open Access Journals (DOAJ), and Bangladesh Journals Online (BanglaJOL) and exclusion criteria (predatory journal and absence of full text in English) and finally selected 63 articles (58 research articles and five (5) reports). The relevant findings on Pb exposure, sources, routes, diet, and impacts in Bangladesh were combined and presented.
The reviewed studies identified 175 Pb contaminated sites through soil sample assessment in Bangladesh. The study determined Pb concentrations in air (0.09-376.58 μg/m
, mean 21.31 μg/m
), river water (0.0009-18.7 mg/l, mean 1.07 mg/l), river sediments (4.9-69.75 mg/kg, mean 32.08 mg/kg), fish (0.018-30.8 mg/kg, mean 5.01 mg/kg), soil (7.3-445 mg/kg, mean 90.34 mg/kg), vegetables (0.2-22.09 mg/kg, mean 4.33 mg/kg) and diet items (0.001-413.9 mg/kg, mean 43.22 mg/kg) of which 38.8%, 27.8%, 54.5%, 68.8%, 9.7% and 100% of samples, respectively, exceeded related World Health Organization (WHO), Food and Agriculture Organization (FAO), United States Environmental Protection Agency (USEPA) and Bangladesh Standard Testing Institution (BSTI) guidelines. The present study found that industrial soils are severely polluted with Pb (7.3-445 mg/kg) in Bangladesh. A high Pb concentration has been found in fish muscle and foods, including leafy and non-leafy vegetables collected from different places in Bangladesh.
Lead-contaminated foods can enter the human body through dietary intake and consequently lead to long-term adverse health effects. This study may help policymakers to formulate national policies with effective mitigation plans to combat the adverse health impacts of Pb in Bangladesh.
The authors declare no competing financial interests.
Due to the diversified lifestyle and fancy ecology associated with Chitra deer (
), deer farming has become popular in Bangladesh. Diseases may be the common constrain of successful deer farming. ...This study aims to investigate the pathological, bacteriological, and nucleic acid based technologies to identify specific causes of morbidity and mortality of captive deer.
Two deer farms and a park deer (designated as farm A, B, and C) entailing 87, 54, and 20 deer, respectively, showed illness and death constitute the study materials. A total of 42 deer died during this investigation. Following death, routine post-mortem examination, histopathology, impression smear staining, isolation, and identification of bacteria were carried out. Polymerase chain reaction (PCR) and reverse transcription PCR were carried out to safeguard the etiology.
Clinically, farm A and B showed the acute phase of illness and park deer showed chronic illness. Case fatality rates were 90%, 92%, and 100% in farms A, B, and C deer, respectively.
and
were identified from the visceral organs of farm A deer. Farm B deer was infected with
type A. Park deer was infected with
and hydatid cyst.
The infectivity in farm A deer was due to stress as induced by punishing weather. The infectivity in farm B deer was due to feeding a higher volume of protein in the diet. The park C deer may optate infection from companion man and animals living around. The diseases of captive deer identified mainly were zoonotic. It needs extensive veterinary services and specialized technologies to identify these diseases, monitor the infectivity and eliminate the public health important diseases at early onset.
•Drought resilience of two tropical tree species was studied.•Species-specific and temporal variability in drought tolerance were observed.•LMEM revealed that growth rates before and after the ...drought events had a dominant role in drought responses.
The frequency and intensity of drought events have increased during the recent decades, particularly in the tropics. Yet, the growth and physiological responses of many tropical tree species to drought are still inadequately understood. We studied the drought resilience of two functionally different canopy tree species (Chukrasia tabularis and Toona ciliata) from a moist tropical forest in Bangladesh during two extreme drought events (1984 and 1999). We quantified four resilience components (resistance, recovery, resilience and relative resilience) of both species to infer drought tolerance of selected trees. Tree radial growth dropped by 44–56% in the drought years, varying with species and drought events. Two species showed no differences in their drought resistance during any of the drought events. However, C. tabularis showed higher recovery and resilience than T. ciliata after the 1999 drought event. T. ciliata showed higher resilience after the 1984 drought event. Linear mixed effect model (LMEM) revealed that growth rates in the two years before and after the drought events had a dominant role in drought responses over tree age, height, diameter, basal area increment and crown exposure, although crown exposure had significant influence on the resistance and the resilience of light demanding T. ciliata. We conclude that diffuse porous and intermediate shade tolerant C. tabularis is more drought tolerant than the ring-porous and light demanding T. ciliata. Since both study species are widely used as plantation species throughout the tropics, our results have important implications for forest managers to take decision on species suitability for plantation programs and to adopt forest management to future climate change conditions.
Global climate change has been reported to affect tree growth around the world and such impacts are predicted to be intensified under future climate change particularly in the tropics. It is ...therefore important to study the climate-growth relationships of tropical trees to understand how they have responded to the past climate variability and to predict how they will respond to future climatic changes. We investigated tree radial growth responses to regional climatic changes in Bangladeshi moist tropical forests. We selected three species based on their distinct growth-ring boundaries and their wide distribution around the tropics. First, we simulated growth responses to climate for the past 66 years (1950–2015) based on the climate-growth relationships. Next, we projected tree-growth until the end of current century (2016–2100) under different climate change scenarios (Representative Concentration Pathways, RCP). All the three species produced statistically robust ring-width index chronologies covering the current and the past century. Climate-growth analysis revealed that temperature (monthly, annual and seasonal) significantly negatively affected tree radial growth in all three species. Precipitation prior to the current growing season negatively and current year post monsoon precipitation positively influenced radial growth. Tree radial growth was also influenced by Niño 3.4 region Sea Surface Temperature (SST) anomalies mainly through the modulation of local climate. We projected tree radial growth to be declined in all three species by 20% under high concentration scenario (RCP 8.5) followed by 11.3% and 9% under medium (RCP 6.0) and low-medium concentration scenarios (RCP 4.5). If these species show similar growth responses to climatic changes in other native ranges across the tropics, this could have severe consequences for the carbon balance of tropical forests.
•Ring-width index chronologies of three South Asian moist forest tree species have been developed.•Climate, particularly temperatures strongly influenced tree growth in all three species.•Tree growth was projected to decline in all species towards the end of current century.
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