Soil Chemical Analysis

Combined effects of climate change and sea-level rise project dramatic habitat loss of the globally endangered Bengal tiger in the Bangladesh Sundarbans

Biomass and aboveground net primary production (ANPP) in a monospecific pioneer stand of a mangrove Kandelia obovata (S., L.) Yong were quantified. The estimated biomasses in leaves, branches, stems, roots, aboveground and total were 5.61 (3.68%), 28.8 (18.9%), 46.1 (30.2%), 71.8 (47.2%), 80.5 (52.8%) and 152 Mg ha−1 (100%), respectively. Stem phytomass increment per tree was estimated using allometric relationships and stem analysis. Stem volume without bark of harvested trees showed a strong allometric relationship with D0.12H (D0.1, diameter at a height of one-tenth of tree height H) (R2 = 0.924). Annual stem volume increment per tree showed a strong allometric relationship with D0.12H (R2 = 0.860). Litterfall rate ranges from 3.87 to 56.1 kg ha−1 day−1 for leaves and 0.177 to 46.2 kg ha−1 day−1 for branches. Seasonal changes of litterfall rate were observed, which showed a peak during wet season (August–September). Total annual litterfall was estimated as 10.6 Mg ha−1 year−1, in which 68.2% was contributed by the leaves. The ANPP in the K. obovata stand was 29.9–32.1 Mg ha−1 year−1, which is ca. 2.8–3.0 times of annual litterfall. The growth efficiency (aboveground biomass increment/LAI) was 5.35–5.98 Mg ha−1 year−1. The low leaf longevity (9.3 months) and high growth efficiency of K. obovata makes it a highly productive mangrove species.

Biomass and aboveground net primary production in a subtropical mangrove stand of Kandelia obovata (S., L.) Yong at Manko Wetland, Okinawa, Japan

[1] Cholera remains a major public health threat in many developing countries around the world. The striking seasonality and annual recurrence of this infectious disease in endemic areas remain of considerable interest to scientists and public health workers. Despite major advances in the ecological and microbiological understanding of Vibrio cholerae, the causative agent of the disease, the role of underlying large-scale hydroclimatic processes in propagating the disease for different seasons and spatial locations is not well understood. Here we show that the cholera outbreaks in the Bengal Delta region are propagated from the coastal to the inland areas and from spring to fall by two distinctly different transmission cycles, premonsoon and postmonsoon, influenced by coastal and terrestrial hydroclimatic processes, respectively. A coupled analysis of the regional hydroclimate and cholera incidence reveals a strong association of the space-time variability of incidence peaks with seasonal processes and extreme climatic events. We explain how the asymmetric seasonal hydroclimatology affects regional cholera dynamics by providing a coastal growth environment for bacteria in spring, while propagating the disease to fall by monsoon flooding. Our findings may serve as the basis for “climate-informed” early warnings and for prompting effective means for intervention and preempting epidemic cholera outbreaks in vulnerable regions.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2010WR009914%4010.1002/%28ISSN%291944-7973.SBRS1

Hydroclimatic influences on seasonal and spatial cholera transmission cycles: Implications for public health intervention in the Bengal Delta

This book answers key questions about environment, people and their shared future in deltas It develops a systematic and holistic approach for policy-orientated analysis for the future of these regions It does so by focusing on ecosystem services in the world’s largest, most populous and most iconic delta region, that of the Ganges-Brahmaputra delta in Bangladesh The book covers the conceptual basis, research approaches and challenges, while also providing a methodology for integration across multiple disciplines, offering a potential prototype for assessments of deltas worldwide Ecosystem Services for Well-Being in Deltas analyses changing ecosystem services in deltas; the health and well-being of people reliant on them; the continued central role of agriculture and fishing; and the implications of aquaculture in such environmentsThe analysis is brought together in an integrated and accessible way to examine the future of the Ganges Brahmaputra delta based on a near decade of research by a team of the world’s leading scientists on deltas and their human and environmental dimensions This book is essential reading for students and academics within the fields of Environmental Geography, Sustainable Development and Environmental Policy focused on solving the world’s most critical challenges of balancing humans with their environments

/pdf/ecosystem-services-for-well-being-in-deltas-integrated-5c6rx6mcsq.pdf

Ecosystem Services for Well-Being in Deltas : Integrated Assessment for Policy Analysis

The world largest mangrove forest, Sundarbans is situated at the western coastal zone of Bangladesh that covers about 40% of the total forest and gives good feedback to the national economy. But for last few years, salinity increasing drastically in this particular region due to sea water intrusion, reduction of fresh water flow and human activities like shrimp farming. In this study both field survey (primary data) and historical (secondary) data were used to assess the present status of salinity rise in Sundarbans area as well as the effect of salinityrise on species destruction like Sundari (Heritiera fomes) which is the climax species of Sundarbans. It was observed that sea level is rising in the Sundarbans coast at the rate of 4 mm/year that is much higher than global trend of 2 mm/year and results more areas to inundate by tidal water. Besides, the water diversion and withdrawal of fresh water in the upstream significantly hampering salt balance system in Sundarbans that leads to permanent and high level of salinity. The soil salinity rise increases with the increase of depth of soil and high level of salinity in the root zone of the plants results a high concentration of sodium salts within the plants body that causes to the reduction of the forest production, restricting the growth of the species like Sundari (Heritiera fomes) and even causes to die.

http://www.indiaenvironmentportal.org.in/files/Present%20status.pdf

Present Status of Salinity Rise in Sundarbans Area and its Effect on Sundari (Heritiera fomes) Species

Model projections predict tropical forests will experience longer periods of drought and more intense precipitation cycles under a changing climate. Such transitions have implications for structure-function relationships within microbial communities. We examine how throughfall exclusion might reshape prokaryotic and fungal communities across four lowland forests in Panama with a wide variation in mean annual precipitation and soil fertility. Four sites were established across a 1000 mm span in Mean Annual Precipitation (MAP: 2335–3421 mm). We expected microbial communities at sites with lower MAP to be less sensitive to throughfall exclusion than sites with higher MAP and fungal communities to be more resistant to disturbance than prokaryotes. At each location, partial throughfall exclusion structures were established over 10 × 10 m plots to reduce direct precipitation input. After short-term (∼3–9 months) throughfall exclusion, prokaryotic communities showed no change in composition. However, prolonged (12–18 months) throughfall exclusion resulted in divergent prokaryotic community responses, reflecting MAP and soil fertility. We observed the emergence of a “drought microbiome” within infertile sites, whereby the community structure of the experimental throughfall exclusion plots at the lower MAP sites diverged from their respective control sites and converged towards overlapping assemblages. Furthermore, under throughfall exclusion, taxa increasing in relative abundance at the wettest site reflected that endemic to control plots at the lowest MAP site, suggesting a shift toward communities with life-history traits selected for under a lower MAP. By contrast, fungal community composition across sites was resilient to throughfall exclusion; however, biomass diverged in response to throughfall exclusion, increasing at two sites while decreasing in the other two. Broadly, our results suggest that microbial communities' sensitivity to frequent drying and rewetting periods in tropical forest soils will depend on climate history and soil fertility, with infertile sites likely to respond readily to changes in precipitation. 

A. K. M. Khurram

Papers

Present Status of Salinity Rise in Sundarbans Area and its Effect on Sundari (Heritiera fomes) Species

Divergent responses of soil microorganisms to throughfall exclusion across tropical forest soils driven by soil fertility and climate history