Responses of the mangrove ecosystem to Holocene environmental change in the Sundarban Biosphere Reserve, India

Abstract

The Sundarban Mangrove Forest in the Sundarban Biosphere Reserve, located at the mouth of the Ganga–Brahmaputra Delta in India, is the most diverse mangrove ecosystem in the world. Sediment cores were taken from two widely separated islands in that reserve: Chamta (CMT) and Sudhyanyakhali (SDK). Pollen analysis and radiocarbon dating were used to study the Holocene development and dynamics of this unique ecosystem. Modern pollen rain study reveals a strong relation between modern pollen rain and the present vegetation, as well as a high rate of Phoenix palludosa pollen production.The pollen records indicate that man-grove existed at CMT from ~5960 and at SDK from ~1520 cal yr BP. Changes in relative sea level, including the frequency and intensity of inundation as well as fluctuating precipitation, have been the major factors along with geomorphic processes that control the development and dynamics of the mangrove in the area during the Holocene. The mid Holocene mangrove at CMT declined, to be progressively replaced by successive communities, and eventually reached climax stage, while the SDK site is transitional in nature. The mangrove responds rapidly to changes in environmental conditions at both locations. Because of large-scale anthropogenic interventions, it is unlikely that similar rapid responses will occur in the future.

ENSO may have contributed to sea level changes in the Gulf of Thailand during the Late-Holocene

“…The correlation between inorganic carbon input and the percentage of the silt and the inverse correlation between inorganic carbon and clay supports this interpretation. Additionally, the inverse relationship between the inorganic carbon input with the relative abundance of Suaeda , a hypersaline herb (Farooqui and Nautiyal, 2016; Hait and Behling, 2009, 2019), indicates a dry period. Dryer conditions will lower the water level, expanding the saline wetland fringe, thus favoring the relative increase of Suaeda , which is more adapted to hypersaline conditions (Farooqui and Nautiyal, 2016).…”

Coastal vegetation dynamics in response to climatic and relative sea level changes in Mahanadi River delta, NE coast of India

“…temperature, precipitation, salinity), research on both local and regional scales is necessary to determine the potential impact of climate change on mangroves (Spalding et al 2010). Many studies have been conducted to understand the response of mangroves to Holocene climate and sea level changes worldwide (Ellison 1989; Parkinson et al 1994; Behling et al 2001; Li et al 2012; Limaye et al 2014; Farooqui et al 2016; Hait and Behling 2019; Rao et al 2020).…”