Climate Variability and Mangrove Cover Dynamics at Species Level in the Sundarbans, Bangladesh

Abstract

Abstract:Mangrove ecosystems are complex in nature. For monitoring the impact of climate variability in this ecosystem, a multidisciplinary approach is a prerequisite. Changes in temperature and rainfall pattern have been suggested as an influential factor responsible for the change in mangrove species composition and spatial distribution. The main aim of this study was to assess the relationship between temperature, rainfall pattern and dynamics of mangrove species in the Sundarbans, Bangladesh, over a 38 year time period from 1977 to 2015. To assess the relationship, a three stage analytical process was employed. Primarily, the trend of temperature and rainfall over the study period were identified using a linear trend model; then, the supervised maximum likelihood classifier technique was employed to classify images recorded by Landsat series and post-classification comparison techniques were used to detect changes at species level. The rate of change of different mangrove species was also estimated in the second stage. Finally, the relationship between temperature, rainfall and the dynamics of mangroves at species level was determined using a simple linear regression model. The results show a significant statistical relationship between temperature, rainfall and the dynamics of mangrove species. The trends of change for Heritiera fomes and Sonneratia apelatala show a strong relationship with temperature and rainfall, while Ceriops decandra shows a weak relationship. In contrast, Excoecaria agallocha and Xylocarpus mekongensis do not show any significant relationship with temperature and rainfall. On the basis of our results, it can be concluded that temperature and rainfall are important climatic factors influencing the dynamics of three major mangrove species viz. H. fomes, S. apelatala and C. decandra in the Sundarbans.

Geospatial modelling of the inundation levels in the Sundarbans mangrove forests due to the impact of sea level rise and identification of affected species and regions

“…Mangroves are considered one of the important constituents as well as the most vulnerable species in the tropical and subtropical inter-tidal ecosystems of the world (Eslami-Andargoli et al 2009). Climate change components, such as changes in rainfall patterns, temperature, concentrations of atmospheric CO 2 , sea-level, high water events, intensity of cyclones and storms, and patterns of ocean circulation are likely to affect mangrove forests (Gilman et al 2008;Ghosh et al 2017). Among them, SLR is considered one of the most important factors affecting the mangroves in terms of their distribution in the long run (Eslami-Andargoli et al 2009;Ghosh et al 2017).…”

“…Maximum likelihood classifier (MLC) algorithm that is widely used in remote sensing applications to classify traditional satellite remote sensing data (Green et al 1998;Gao 1999) was adopted in this study to identify the mangrove population by species. Prior to fieldwork, the first author's extensive field experience, and information from published literature (Chaffey et al 1985;Treygo and Dean 1989;Emch and Peterson 2006;Giri et al 2007;Ghosh et al 2016Ghosh et al , 2017 were used to select five major mangrove species out of 19 known species of Bangladesh Sundarbans (Sarker et al 2016) for this classification. The main aim of this research was to model the impact of SLR on the spatial distribution of major mangrove species in the Sundarbans, Bangladesh.…”

“…Investigation has shown that climatic variables of temperature and rainfall influence the composition and distribution of major mangrove species viz. Heritiera fomes, Sonneratia apelatala and Ceriops decandra in the Sundarbans (Ghosh et al 2017). The global SLR is projected to be approximately 1 m higher or above by the year 2100 (Church et al 2013;Payo et al 2016), but future impacts on composition and distribution of mangrove species remains largely unknown.…”

Drivers of mangrove ecosystem service change in the Sundarbans of Bangladesh

“…() also found that over the period 1977–2015, average maximum and minimum temperature have been increasing in the Sundarbans, while annual total rainfall has been decreasing which has considerable impacts on mangrove canopy coverage. Increasing temperature trends could affect mangroves by changing phenological patterns and species composition (Gilman et al ., ; Ghosh et al ., ). Ghosh et al .…”

“…Ghosh et al . () found that the dominant mangrove tree species Sundri ( H. fomes ) has decreased considerably with the increase of average maximum temperature. Fish physiology, growth and reproduction are directly influenced by temperature (Chowdhury et al ., ) and the breeding performance of many commercial mangrove fisheries species such as finfish (especially Mugil spp.…”