Invited Seminar at CES on 6 December 2023 at 3:00 pm titled "Mangrove forest dynamics in response to climatic and sea level changes along the Indian coastline" by Dr Jyoti Srivastava from Scientist-D, Quaternary Paleoclimate Division, Birbal Sahni Instit
Mangrove forests inhabit the intertidal areas along the tropical and subtropical coastal regions and monitor the exchange of matter at the edges of terrestrial, marine and atmospheric ecosystem. This specialized ecosystem offers several ecosystem services, like alleviating coastal erosion by wind and waves, ensuring fishery resources and food security for coastal population, and protecting the coastal biodiversity. It plays a key role in carbon exchange cycle and is an important blue carbon sink that can aid in the mitigation of climate change. However, mangroves are highly vulnerable to climate change and fluctuations in relative sea level. The mangroves are harmed by low intensity precipitation due to less freshwater discharge, fluvial silt, and nutrient input into the mangrove habitats. High frequency winter cooling episodes can also hinder mangrove development due to variations in monsoon intensity. Hypersaline environments with high evaporation rates brought on by extreme warming episodes also cause mangrove forest degradation. Moreover, anthropogenic pressures, such as overexploitation of resources, environmental pollution, and landuse/landcover changes, have greatly impacted the mangrove ecosystem. Currently, the world is seeing rapid sea level rise, frequent extreme climatic events, and an ever-rising population. Hence, the reconstruction of past mangrove responses through climate indicators recorded in sediments provides a baseline data for species distribution models in predicting the fate of mangrove ecosystem under the influence of rapid environmental changes.
Fossil pollen plays a vital role as a direct proxy for estimating vegetation cover in the past and an indirect proxy for understanding past climate. Palynological assemblages from estuarine formations are constantly influenced by both marine and terrestrial factors such as coastal erosion, accretion by rivers or sea, tidal waves, high salinity, water-logged soils and other edaphic factors due to their location along coasts. This, along with the distance from shoreline, duration and frequency of tidal inundation govern the distribution of mangrove species and their succession. Hence, studies attempting to identify the modern pollen dispersion and deposition processes, test correlations between pollen, vegetation, and climate using models, and compare these models with fossil pollen databases for reconstructing the key plant species distribution at a continental spatial scale are much needed for climate modelling studies.