PALAEOCON · Conservation palaeobiology of terrestrial and marine carbon sinks

Conservation palaeobiology of terrestrial and marine carbon sinks

The ecosystems that are able to accumulate and store carbon are of great importance in the context of current and future scenarios of Global Change. Peatlands and seagrass meadows are carbon sink ecosystems. Unfortunately, they are threatened by perturbations originated by both humans and climate, so the environmental and economic consequences of their loss are incalculable. Therefore, the conservation of natural carbon sinks has been proposed as a key objective in order to buffer carbon dioxide emissions, as recognised in the Paris Agreement in 2015. The processes and dynamics of these important ecosystems involve time scales from decades to millennia. However, owing to environmental monitoring covers a few decades at best, millennial-long environmental records capturing long-term dynamics can only be obtained using a palaeoecological approach. The overall aim of PALAEOCON is to use the palaeoecological record to obtain a millennial-long environmental monitoring of terrestrial and marine carbon sinks in order to understand the resilience of peatlands and seagrass meadows. The environmental archives selected are located in Spain, a country that would be severely affected by global change according to IPCC climate scenarios. We propose a multi-proxy approach combining biological and non-biological indicators on peatland cores and Posidonia oceanica mat cores. Using the information stored in these environmental archives we plan the detection of baselines and tipping points that could inform conservation. During the 10 months that the action has lasted, we have obtained several insights. - Colorimetric and Fourier-transformed infrared spectroscopic analyses of peatland cores allowed us to find that for the peatlands analysed chromo-stratigraphical changes are an indirect proxy for organic matter content, so it can be used as a first approximation when planning further analyses. In addition, the spectroscopic results highlighted the importance of considering the molecular composition of the organic matter together with the elemental composition if information on mineralisation (i.e., carbon dioxide release) of the organic matter wants to be obtained. - The palynological, charcoal and magnetic susceptibility analyses of P. oceanica mats provided information on human activities in the terrestrial environment that triggered soil erosion and had an impact on the amount of inorganic content entering the coastal area, impacting the organic matter accumulation in the seagrass ecosystem. Finally, the preliminary results of dinoflagellate cyst records from the seagrass cores have supported the study of fossil pigments in order to reconstruct the factors that regulated primary producers’ assemblages in P. oceanica meadows for the last eighteen centuries. Global climate factors explained the detected changes in algal assemblages that could, in turn, impact the seagrass ecosystem functioning.

Data: CORDIS, © European Union