Bangladesh is a deltaic country with a 710 km coastline and numerous newly accreted offshore islands in the central and eastern coastal regions. Natural mangrove forest (the Sundarbans) occupies about 100 km of coastl...Bangladesh is a deltaic country with a 710 km coastline and numerous newly accreted offshore islands in the central and eastern coastal regions. Natural mangrove forest (the Sundarbans) occupies about 100 km of coastline in the southwest, which protects the lives and properties of the coastal population of that area. The depletion of the forest stock of the Sundarbans was reported in 1875 due to the large-scale clearings by the woodcutters and uncertainty in natural regeneration. The restoration of the Sundarbans in the name of enrichment plantation and assisted natural regeneration was formally introduced in 1959 with Excoecaria agallocha followed by the introduction of mangrove and mainland (non-mangrove) species in the moderate to high saline zone and raised lands in the freshwater zone, respectively in 1975. Chakaria Sundarbans, the second largest natural mangrove forest on the east coast, was highly degraded with the rapid expansion of aquaculture between 1976 and 1989. Tremendous human interferences significantly altered the site condition, interrupting natural recovery. Coastal afforestation was initiated in 1966 with two pioneer mangrove species (Sonneratia apetala and Avicennia officinalis). Some afforested sites require attention for restoration due to natural and manmade causes. Bangladesh Forest Department adopted restoration activities with the technical support of the Bangladesh Forest Research Institute and other agencies. However, all the restoration activities for the Sundarbans, Chakaria Sundarbans, and coastal afforested sites had some success and failure stories. The success and failure of a mangrove restoration activity depends on planning (active or passive restoration), selection of suitable sites and species, planting materials, local community involvement, monitoring, evaluation and plantation management.展开更多
<em>Xylocarpus mekongensis</em> Pierre is the important tree species of the Sundarbans. The present study was conducted to evaluate the effect of salinity on the survival and growth of <em>X. mekonge...<em>Xylocarpus mekongensis</em> Pierre is the important tree species of the Sundarbans. The present study was conducted to evaluate the effect of salinity on the survival and growth of <em>X. mekongensis</em> seedlings. The distributional patterns of nitrogen, phosphorus, potassium, sodium, and carbon in seedling parts were also examined in relation to salinity. Comparatively higher survival (95%) of seedlings was observed at non-saline to slightly saline conditions (0-5 PSU) and it was decreased to 78% at 35 PSU salinity. The relative growth rate (RGR) was higher at non-saline to slightly saline (0 to 5 PSU) conditions compared to higher salinity. Nutrients, sodium, and carbon concentration are found to vary significantly (p < 0.05) among the parts of seedlings. Comparatively (p < 0.05) highest concentration of nitrogen (20 to 34 mg/g), phosphorus (0.50 to 0.75 mg/g), potassium (9 to 27 mg/g) and sodium (7 to 36 mg/g) were found in leaves, while the highest concentration of carbon (42% to 45%) was detected in the stem. However, nitrogen, potassium, and carbon concentration in different parts of seedlings showed significant (p < 0.05) negative correlations with salinity levels. It can be concluded that <em>X. mekongensis</em> has the capacity to tolerate higher saline condition but they grow well in non-saline to less saline conditions.展开更多
Biomass and carbon stock in a forested areas are now prime important indicators of forest management and climate change mitigation measures. But the accurate estimation of biomass and carbon in trees of forests is now...Biomass and carbon stock in a forested areas are now prime important indicators of forest management and climate change mitigation measures. But the accurate estimation of biomass and carbon in trees of forests is now a challenging issue. In most cases, pantropical and regional biomass models are used frequently to estimate biomass and carbon stock in trees, but these estimation</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> have some uncertainty compared to the species-specific allometric biomass model. </span><i><span style="font-family:Verdana;">Acacia</span></i><span> <i><span style="font-family:Verdana;">nilotica</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">Casuarina</span></i> <i><span style="font-family:Verdana;">equisetifolia</span></i></span><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Melia</span></i><span style="font-family:Verdana;"> <i>azedarach</i> </span><span style="font-family:Verdana;">have been planted in different areas of Bangladesh considering the species-specific site requirements. While </span><i><span style="font-family:Verdana;">Barringtonia</span></i><span style="font-family:Verdana;"> <i>acutangula</i></span><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Pongamia</span></i><span style="font-family:Verdana;"> <i>pinnata</i> </span><span style="font-family:Verdana;">are the dominant tree species of the freshwater swamp forest of Bangladesh. This study was aimed to develop species-specific allometric biomass models for estimating stem and above ground biomass (TAGB) of these species using the non-destructive method and to compare the efficiency of the derived biomass models with the frequently used regional and pantropical biomass models. Four Ln-based models with diameter at breast height (DBH) and total height (H) were tested to derive the best fit allometric model. Among the tested models, Ln (biomass) = a + b Ln (D) + c Ln (H) was the best-fit model for </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">nilotica</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">M</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">azedarach</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">B</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">acutangula</span></i> </span><span style="font-family:Verdana;">and</span><span> <i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">pinnata</span></i> </span><span style="font-family:Verdana;">and Ln (biomass) = a + b Ln (D</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">H) was best-fit for </span><i><span style="font-family:Verdana;">C</span></i><span><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">equisetifolia</span></i><span style="font-family:Verdana;">. </span></span><span style="font-family:Verdana;">Finally</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the derived best-fit species-specific TAGB models have shown superiority over the other frequently used pantropical and regional biomass models in relation to model efficiency and model prediction error.展开更多
Aegiceras corniculatum grows as single-stemmed evergreen shrub or small tree in the Sundarbans mangrove forest of Bangladesh. The objectives of this study were to derive the allometric models for estimating above-grou...Aegiceras corniculatum grows as single-stemmed evergreen shrub or small tree in the Sundarbans mangrove forest of Bangladesh. The objectives of this study were to derive the allometric models for estimating above-ground biomass, nutrients (N, P and K) and carbon stock in A. corniclatum. A total of 8 linear models (y = aX + b, , y = aLogX + b, Logy = aX + b, Logy = aLogX + b, y = alnX + b, Lny = aX + b and Lny = alnX + b) with 64 regression equations were tested to derive the allometric model for biomass of each plant part;and nutrients and carbon stock in total aboveground biomass. The best fit allometric models were selected by considering the values of R<sup>2</sup>, CV, R<sub>mse</sub>, MS<sub>error</sub>, S<sub>a</sub>, S<sub>b</sub>, F value, AICc and Furnival Index. The selected allometric models were Logbiomass = 0.76LogDBH<sup>2</sup> - 1.39;Biomass = 0.07DBH<sup>2</sup> - 0.49;Logbiomass = 1.04LogDBH<sup>2</sup> - 1.80;Logbiomass = 1.04LogDBH<sup>2</sup> - 0.99;= 0.48DBH - 0.13 for leaves, branches, bark, stem without bark and total above-ground biomass respectively. The selected allometric models for Nitrogen, Phosphorous, Potassium and Carbon stock in total above-ground biomass were = 0.67DBH + 0.11;= 0.94DBH + 0.08;= 1.06DBH - 0.18;= 0.33DBH - 0.09 respectively.展开更多
The Sundarbans is the world’s most extensive natural mangrove forest and home to various natural resources. The population in the vicinity has increased, causing more dependency on the resources of the Sundarbans. Th...The Sundarbans is the world’s most extensive natural mangrove forest and home to various natural resources. The population in the vicinity has increased, causing more dependency on the resources of the Sundarbans. The increasing industrialization, urbanization, aquaculture, intensive agricultural practices, seaports, tourism facilities, and so on in the peripheral areas of the Sundarbans have made significant changes in the surrounding and upstream land uses of the Sundarbans. This situation may have detrimental influences on the ecosystem components of the Sundarbans. Therefore, it is highly demanded to prepare a piece of baseline information or database of different sources of pollution and their present status in the various components of the Sundarbans. This effort helps to identify issues and concerns, determine the key elements of the ecosystem to monitor the level or overall quality of the Sundarbans ecosystem. The present study systematically collects the potential sources of pollution, types, and current levels in the ecosystem components of the Sundarbans using academic databases, libraries, and online resources. Discharge of industrial waste into water, soil and air, heavy metal pollution, use of agrochemicals, oil (refined and crude) pollution, plastic materials from urban areas, and tourism are the major issues and concerns related to the sustainability of the Sundarbans ecosystem. The air quality of the Sundarbans is in good condition with 0 - 50 AQI of Bangladesh. While BOD, COD, TDS, TSS varied from 2.0 to 3.8 mg/L, 21.6 to 416 mg/L, 146.9 to 24,100 mg/L and 54 to 155 mg/L, respectively. Soil EC, organic carbon, total nitrogen, and total phosphorus ranged from 3.01 - 5.82 mS/cm, 1.41% - 2.69%, 0.51 - 1.05 mg/g, and 0.32 - 0.51 mg/g respectively. The air, water and soil quality parameters varied with the sites and seasons and not much at the state of contamination. Indeed, we must pay much attention to the Sundarbans’ air, water and soil quality with the massive and progressive change of the nearby land use pattern.展开更多
Azadirachta indica A. Juss, Dalbergia, sissoo Roxb., and Melia azedarach L. are little studied species in nutrient return capabilities from leaf litter decomposition to maintenance of the soil fertility despite their ...Azadirachta indica A. Juss, Dalbergia, sissoo Roxb., and Melia azedarach L. are little studied species in nutrient return capabilities from leaf litter decomposition to maintenance of the soil fertility despite their importance in agroforestry practices of Bangladesh. A leaf litter decomposition experiment was conducted using a litterbag teeh7 nique to assess the nutrient reaun efficiency of these species. The de- composition rate of leaf litter was highest for M. azedarach and lowest for D. sissoo. Rainfall and temperature of study sites showed a significant （p〈0.05） positive relationship with the rate of leaf litter decomposition. The highest decay constant was observed for M. azedarach （6.67）. Nitrogen and Phosphorus concentration in leaf litter showed a decreased trend sharply at the end of the first month, whereas rapid decrease of Potassium concentration was reported within 10 days. Conversely, higher concentration of nutrient was observed at the later stages of decomposition. All three species showed a similar pattern of nutrient release （K 〉 N 〉 P） during the decomposition process of leaf litter. Among the studied species, D. sissoo was best in terms of N and P return and A. indica was best in terms of K return.展开更多
Tree biomass plays a key role in sustainable management by providing different aspects of ecosystem. Estimation of above ground biomass by non-destructive means requires the dex;elopment of allometric equations. Most ...Tree biomass plays a key role in sustainable management by providing different aspects of ecosystem. Estimation of above ground biomass by non-destructive means requires the dex;elopment of allometric equations. Most researchers used DBH （diameter at breast height） and TH （total height） to develop allometric equation for a tree. Very few spe- cies-specific allometric equations are currently available for shrubs to estimate of biomass from measured plant attributes. Therefore, we used some of readily measurable variables to develop allometric equations such as girth at collar-height （GcH） and height of girth measuring point （GMH） with total height （TH） for A. rotundifolia, a mangrove species of Sundarbans of Bangladesh, as it is too dwarf to take DBH and too ir- regular in base to take Girth at a fixed height. Linear, non-linear and logarithmic regression techniques were tried to determine the best re- gression model to estimate the above-ground biomass of stem, branch and leaf. A total of 186 regression equations were generated from the combination of independent variables. Best fit regression equations were determined by examining co-efficient of determination （R：）, co-efficient of variation （Cv）, mean-square of the error （Ms^r）, residual mean error （Rmax）, and F-value. Multiple linear regression models showed more efficient over other types of regression equation. The performance of regression equations was increased by inclusion of GMn as an independ- ent variable along with total height and GCH.展开更多
Allometric biomass models are efficient tools to estimate biomass of trees and forest stands in a non-destructive way. Development of species-specific allometric biomass models requires extensive fieldwork and time. O...Allometric biomass models are efficient tools to estimate biomass of trees and forest stands in a non-destructive way. Development of species-specific allometric biomass models requires extensive fieldwork and time. Our study aimed to generate species-specific allometric biomass models for the most common fuelwood and timber species of Bangladesh. We also wanted to evaluate the performances of our models relative to the performances of regional and commonly used pan-tropical biomass models. We used semi-destructive method that incorporates tree-level volume, species-specific biomass expansion factor (BEF), and wood density. We considered four base models, 1) Ln (biomass) = a + bLn (D);2) Ln (biomass) = a + bLn (H);3) Ln (Biomass) = a + bLn (D^2H);4) Ln (Biomass) = a + bLn (D) + cLn (H) to develop species-specific best-fitted models for Total Above-Ground Biomass (TAGB) and stem biomass. The best-fitted model for each species was selected by the lowest value of Akaike Information Criterion (AIC), Residual Standard Error (RSE) and Root Mean Square Error (RMSE). The derived best-fitted models were then evaluated with respect to regional and pan-tropical models using a separate set of observed data. This evaluation was conducted by computing ME (Model Efficiency) and MPE (Model Prediction Error). The best-fitted allometric biomass models have shown higher model efficiency (0.85 to 0.99 at scale 1) and the lowest model prediction error (-8.94% to 5.27%) compared to the regional and pan-tropical models. All the examined regional and pan-tropical biomass models showed different magnitude of ME and MPE. Some models showed higher level (>0.90 at scale 1) of ME compared to the best-fitted specific species biomass model.展开更多
Cropland agroforest is an important production system in the southwest region of Bangladesh. This study focused on the floristic composition and management of existing cropland agroforests. A total of 313 cropland agr...Cropland agroforest is an important production system in the southwest region of Bangladesh. This study focused on the floristic composition and management of existing cropland agroforests. A total of 313 cropland agroforests were surveyed and 83%respondents practiced pure agroforestry while the remaining 17% practiced agroforestry with fisheries. A total of 18 forest trees and 2 shrubs were recorded from 11 families and 59 species of agricultural crops were from 28 families. A higher proportion （79%） of cropland agroforests were occupied small land areas （0.12-0.80 ha）. About 63% of respondents planted trees for fruit production and 47%for timber production, and 35%of respondents engaged in commercial production （35%）. Swietenia macrophylla was the most prevalent species （relative prevalence 20.83） followed by Man-gifera indica （relative prevalence 15.57） and Cocos nucifera （relative prevalence 7.08）. Shorter spacing was used for timber and fuel wood species and wider spacing for fruit trees. A wide range of rotation periods, from 5 to 25 years, was observed for both cases. The use of chemical fertilizer was highest followed by cow dung and compost in cropland agroforests. Overall management practices of cropland agroforest in southwest Bangladesh were determined by the end product and local demand.展开更多
Bangladesh (Indo-Bangladesh to independent Bangladesh) has more than 250 years of history in forest inventory. The Boundary demarcation of the Sundarbans forest in 1764 was the first record of forest inventory. A tota...Bangladesh (Indo-Bangladesh to independent Bangladesh) has more than 250 years of history in forest inventory. The Boundary demarcation of the Sundarbans forest in 1764 was the first record of forest inventory. A total of 30 inventories have been recorded that were started to form the boundary demarcation to complex biodiversity, biomass, and carbon stock assessment. These inventories used simple cartographic to complex satellite image processing techniques, software base data/information collection methods, and sophisticated statistical procedures in data analysis. Eventually, the history of the forest inventory of Bangladesh is about 100 years older than the history of forest management. This study aimed to classify the inventories into distinct time frames based on outputs and align them with the motive of rulers, existing forest policy, and contemporary global and national issues. The historical records forest inventory has been divided into four distinct periods, e.g., Mid eighteenth to the late nineteenth century: 1764-1876;Early twenty century: 1905-1924;Mid-twenty to late twenty century: 1958-2000;and Early twenty-first century: 2001-present). The objectives/outputs of each inventory were highly linked with the motive of rulers, policy statements, available technologies, and recent issues from national and global perspectives.展开更多
文摘Bangladesh is a deltaic country with a 710 km coastline and numerous newly accreted offshore islands in the central and eastern coastal regions. Natural mangrove forest (the Sundarbans) occupies about 100 km of coastline in the southwest, which protects the lives and properties of the coastal population of that area. The depletion of the forest stock of the Sundarbans was reported in 1875 due to the large-scale clearings by the woodcutters and uncertainty in natural regeneration. The restoration of the Sundarbans in the name of enrichment plantation and assisted natural regeneration was formally introduced in 1959 with Excoecaria agallocha followed by the introduction of mangrove and mainland (non-mangrove) species in the moderate to high saline zone and raised lands in the freshwater zone, respectively in 1975. Chakaria Sundarbans, the second largest natural mangrove forest on the east coast, was highly degraded with the rapid expansion of aquaculture between 1976 and 1989. Tremendous human interferences significantly altered the site condition, interrupting natural recovery. Coastal afforestation was initiated in 1966 with two pioneer mangrove species (Sonneratia apetala and Avicennia officinalis). Some afforested sites require attention for restoration due to natural and manmade causes. Bangladesh Forest Department adopted restoration activities with the technical support of the Bangladesh Forest Research Institute and other agencies. However, all the restoration activities for the Sundarbans, Chakaria Sundarbans, and coastal afforested sites had some success and failure stories. The success and failure of a mangrove restoration activity depends on planning (active or passive restoration), selection of suitable sites and species, planting materials, local community involvement, monitoring, evaluation and plantation management.
文摘<em>Xylocarpus mekongensis</em> Pierre is the important tree species of the Sundarbans. The present study was conducted to evaluate the effect of salinity on the survival and growth of <em>X. mekongensis</em> seedlings. The distributional patterns of nitrogen, phosphorus, potassium, sodium, and carbon in seedling parts were also examined in relation to salinity. Comparatively higher survival (95%) of seedlings was observed at non-saline to slightly saline conditions (0-5 PSU) and it was decreased to 78% at 35 PSU salinity. The relative growth rate (RGR) was higher at non-saline to slightly saline (0 to 5 PSU) conditions compared to higher salinity. Nutrients, sodium, and carbon concentration are found to vary significantly (p < 0.05) among the parts of seedlings. Comparatively (p < 0.05) highest concentration of nitrogen (20 to 34 mg/g), phosphorus (0.50 to 0.75 mg/g), potassium (9 to 27 mg/g) and sodium (7 to 36 mg/g) were found in leaves, while the highest concentration of carbon (42% to 45%) was detected in the stem. However, nitrogen, potassium, and carbon concentration in different parts of seedlings showed significant (p < 0.05) negative correlations with salinity levels. It can be concluded that <em>X. mekongensis</em> has the capacity to tolerate higher saline condition but they grow well in non-saline to less saline conditions.
文摘Biomass and carbon stock in a forested areas are now prime important indicators of forest management and climate change mitigation measures. But the accurate estimation of biomass and carbon in trees of forests is now a challenging issue. In most cases, pantropical and regional biomass models are used frequently to estimate biomass and carbon stock in trees, but these estimation</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> have some uncertainty compared to the species-specific allometric biomass model. </span><i><span style="font-family:Verdana;">Acacia</span></i><span> <i><span style="font-family:Verdana;">nilotica</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">Casuarina</span></i> <i><span style="font-family:Verdana;">equisetifolia</span></i></span><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Melia</span></i><span style="font-family:Verdana;"> <i>azedarach</i> </span><span style="font-family:Verdana;">have been planted in different areas of Bangladesh considering the species-specific site requirements. While </span><i><span style="font-family:Verdana;">Barringtonia</span></i><span style="font-family:Verdana;"> <i>acutangula</i></span><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Pongamia</span></i><span style="font-family:Verdana;"> <i>pinnata</i> </span><span style="font-family:Verdana;">are the dominant tree species of the freshwater swamp forest of Bangladesh. This study was aimed to develop species-specific allometric biomass models for estimating stem and above ground biomass (TAGB) of these species using the non-destructive method and to compare the efficiency of the derived biomass models with the frequently used regional and pantropical biomass models. Four Ln-based models with diameter at breast height (DBH) and total height (H) were tested to derive the best fit allometric model. Among the tested models, Ln (biomass) = a + b Ln (D) + c Ln (H) was the best-fit model for </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">nilotica</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">M</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">azedarach</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">B</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">acutangula</span></i> </span><span style="font-family:Verdana;">and</span><span> <i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">pinnata</span></i> </span><span style="font-family:Verdana;">and Ln (biomass) = a + b Ln (D</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">H) was best-fit for </span><i><span style="font-family:Verdana;">C</span></i><span><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">equisetifolia</span></i><span style="font-family:Verdana;">. </span></span><span style="font-family:Verdana;">Finally</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the derived best-fit species-specific TAGB models have shown superiority over the other frequently used pantropical and regional biomass models in relation to model efficiency and model prediction error.
文摘Aegiceras corniculatum grows as single-stemmed evergreen shrub or small tree in the Sundarbans mangrove forest of Bangladesh. The objectives of this study were to derive the allometric models for estimating above-ground biomass, nutrients (N, P and K) and carbon stock in A. corniclatum. A total of 8 linear models (y = aX + b, , y = aLogX + b, Logy = aX + b, Logy = aLogX + b, y = alnX + b, Lny = aX + b and Lny = alnX + b) with 64 regression equations were tested to derive the allometric model for biomass of each plant part;and nutrients and carbon stock in total aboveground biomass. The best fit allometric models were selected by considering the values of R<sup>2</sup>, CV, R<sub>mse</sub>, MS<sub>error</sub>, S<sub>a</sub>, S<sub>b</sub>, F value, AICc and Furnival Index. The selected allometric models were Logbiomass = 0.76LogDBH<sup>2</sup> - 1.39;Biomass = 0.07DBH<sup>2</sup> - 0.49;Logbiomass = 1.04LogDBH<sup>2</sup> - 1.80;Logbiomass = 1.04LogDBH<sup>2</sup> - 0.99;= 0.48DBH - 0.13 for leaves, branches, bark, stem without bark and total above-ground biomass respectively. The selected allometric models for Nitrogen, Phosphorous, Potassium and Carbon stock in total above-ground biomass were = 0.67DBH + 0.11;= 0.94DBH + 0.08;= 1.06DBH - 0.18;= 0.33DBH - 0.09 respectively.
文摘The Sundarbans is the world’s most extensive natural mangrove forest and home to various natural resources. The population in the vicinity has increased, causing more dependency on the resources of the Sundarbans. The increasing industrialization, urbanization, aquaculture, intensive agricultural practices, seaports, tourism facilities, and so on in the peripheral areas of the Sundarbans have made significant changes in the surrounding and upstream land uses of the Sundarbans. This situation may have detrimental influences on the ecosystem components of the Sundarbans. Therefore, it is highly demanded to prepare a piece of baseline information or database of different sources of pollution and their present status in the various components of the Sundarbans. This effort helps to identify issues and concerns, determine the key elements of the ecosystem to monitor the level or overall quality of the Sundarbans ecosystem. The present study systematically collects the potential sources of pollution, types, and current levels in the ecosystem components of the Sundarbans using academic databases, libraries, and online resources. Discharge of industrial waste into water, soil and air, heavy metal pollution, use of agrochemicals, oil (refined and crude) pollution, plastic materials from urban areas, and tourism are the major issues and concerns related to the sustainability of the Sundarbans ecosystem. The air quality of the Sundarbans is in good condition with 0 - 50 AQI of Bangladesh. While BOD, COD, TDS, TSS varied from 2.0 to 3.8 mg/L, 21.6 to 416 mg/L, 146.9 to 24,100 mg/L and 54 to 155 mg/L, respectively. Soil EC, organic carbon, total nitrogen, and total phosphorus ranged from 3.01 - 5.82 mS/cm, 1.41% - 2.69%, 0.51 - 1.05 mg/g, and 0.32 - 0.51 mg/g respectively. The air, water and soil quality parameters varied with the sites and seasons and not much at the state of contamination. Indeed, we must pay much attention to the Sundarbans’ air, water and soil quality with the massive and progressive change of the nearby land use pattern.
基金supported by Bangladesh Academy of Science and University Grants Commissions of Bangladesh
文摘Azadirachta indica A. Juss, Dalbergia, sissoo Roxb., and Melia azedarach L. are little studied species in nutrient return capabilities from leaf litter decomposition to maintenance of the soil fertility despite their importance in agroforestry practices of Bangladesh. A leaf litter decomposition experiment was conducted using a litterbag teeh7 nique to assess the nutrient reaun efficiency of these species. The de- composition rate of leaf litter was highest for M. azedarach and lowest for D. sissoo. Rainfall and temperature of study sites showed a significant （p〈0.05） positive relationship with the rate of leaf litter decomposition. The highest decay constant was observed for M. azedarach （6.67）. Nitrogen and Phosphorus concentration in leaf litter showed a decreased trend sharply at the end of the first month, whereas rapid decrease of Potassium concentration was reported within 10 days. Conversely, higher concentration of nutrient was observed at the later stages of decomposition. All three species showed a similar pattern of nutrient release （K 〉 N 〉 P） during the decomposition process of leaf litter. Among the studied species, D. sissoo was best in terms of N and P return and A. indica was best in terms of K return.
文摘Tree biomass plays a key role in sustainable management by providing different aspects of ecosystem. Estimation of above ground biomass by non-destructive means requires the dex;elopment of allometric equations. Most researchers used DBH （diameter at breast height） and TH （total height） to develop allometric equation for a tree. Very few spe- cies-specific allometric equations are currently available for shrubs to estimate of biomass from measured plant attributes. Therefore, we used some of readily measurable variables to develop allometric equations such as girth at collar-height （GcH） and height of girth measuring point （GMH） with total height （TH） for A. rotundifolia, a mangrove species of Sundarbans of Bangladesh, as it is too dwarf to take DBH and too ir- regular in base to take Girth at a fixed height. Linear, non-linear and logarithmic regression techniques were tried to determine the best re- gression model to estimate the above-ground biomass of stem, branch and leaf. A total of 186 regression equations were generated from the combination of independent variables. Best fit regression equations were determined by examining co-efficient of determination （R：）, co-efficient of variation （Cv）, mean-square of the error （Ms^r）, residual mean error （Rmax）, and F-value. Multiple linear regression models showed more efficient over other types of regression equation. The performance of regression equations was increased by inclusion of GMn as an independ- ent variable along with total height and GCH.
文摘Allometric biomass models are efficient tools to estimate biomass of trees and forest stands in a non-destructive way. Development of species-specific allometric biomass models requires extensive fieldwork and time. Our study aimed to generate species-specific allometric biomass models for the most common fuelwood and timber species of Bangladesh. We also wanted to evaluate the performances of our models relative to the performances of regional and commonly used pan-tropical biomass models. We used semi-destructive method that incorporates tree-level volume, species-specific biomass expansion factor (BEF), and wood density. We considered four base models, 1) Ln (biomass) = a + bLn (D);2) Ln (biomass) = a + bLn (H);3) Ln (Biomass) = a + bLn (D^2H);4) Ln (Biomass) = a + bLn (D) + cLn (H) to develop species-specific best-fitted models for Total Above-Ground Biomass (TAGB) and stem biomass. The best-fitted model for each species was selected by the lowest value of Akaike Information Criterion (AIC), Residual Standard Error (RSE) and Root Mean Square Error (RMSE). The derived best-fitted models were then evaluated with respect to regional and pan-tropical models using a separate set of observed data. This evaluation was conducted by computing ME (Model Efficiency) and MPE (Model Prediction Error). The best-fitted allometric biomass models have shown higher model efficiency (0.85 to 0.99 at scale 1) and the lowest model prediction error (-8.94% to 5.27%) compared to the regional and pan-tropical models. All the examined regional and pan-tropical biomass models showed different magnitude of ME and MPE. Some models showed higher level (>0.90 at scale 1) of ME compared to the best-fitted specific species biomass model.
基金supported by Bangladesh Academy of Sciences(BAS)United States Department of Agriculture(USDA)
文摘Cropland agroforest is an important production system in the southwest region of Bangladesh. This study focused on the floristic composition and management of existing cropland agroforests. A total of 313 cropland agroforests were surveyed and 83%respondents practiced pure agroforestry while the remaining 17% practiced agroforestry with fisheries. A total of 18 forest trees and 2 shrubs were recorded from 11 families and 59 species of agricultural crops were from 28 families. A higher proportion （79%） of cropland agroforests were occupied small land areas （0.12-0.80 ha）. About 63% of respondents planted trees for fruit production and 47%for timber production, and 35%of respondents engaged in commercial production （35%）. Swietenia macrophylla was the most prevalent species （relative prevalence 20.83） followed by Man-gifera indica （relative prevalence 15.57） and Cocos nucifera （relative prevalence 7.08）. Shorter spacing was used for timber and fuel wood species and wider spacing for fruit trees. A wide range of rotation periods, from 5 to 25 years, was observed for both cases. The use of chemical fertilizer was highest followed by cow dung and compost in cropland agroforests. Overall management practices of cropland agroforest in southwest Bangladesh were determined by the end product and local demand.
文摘Bangladesh (Indo-Bangladesh to independent Bangladesh) has more than 250 years of history in forest inventory. The Boundary demarcation of the Sundarbans forest in 1764 was the first record of forest inventory. A total of 30 inventories have been recorded that were started to form the boundary demarcation to complex biodiversity, biomass, and carbon stock assessment. These inventories used simple cartographic to complex satellite image processing techniques, software base data/information collection methods, and sophisticated statistical procedures in data analysis. Eventually, the history of the forest inventory of Bangladesh is about 100 years older than the history of forest management. This study aimed to classify the inventories into distinct time frames based on outputs and align them with the motive of rulers, existing forest policy, and contemporary global and national issues. The historical records forest inventory has been divided into four distinct periods, e.g., Mid eighteenth to the late nineteenth century: 1764-1876;Early twenty century: 1905-1924;Mid-twenty to late twenty century: 1958-2000;and Early twenty-first century: 2001-present). The objectives/outputs of each inventory were highly linked with the motive of rulers, policy statements, available technologies, and recent issues from national and global perspectives.
