Evaluation of palm swamps palaeocology related to past climatic and human practices variability: The study case of the Orinoco Delta

Abstract

PROJECT AIMS: The paucity of palaeoecological data is acute in the Neotropics, where the low number of good quality records (with reliable dating and continuous sedimentation) prevents the development of a regional understanding of the vegetation and climate dynamics. Within the Neotropics, low wetlands are particularly poorly known due to the scarcity of potential archives. We present here an ongoing project designed to improve the understanding of wetland forests' responses to changes in climatic and human variability by studying their long-term dynamics. The project will focus on specific scales for maximising the accuracy of the outputs: I) the geographic area (northern South American wetlands), and ii) the time period (last 6 kyr). The region has been chosen because of the occurrence of globally important big wetland areas dominated by the palm Mauritania flexuosa and the perceived threats to the fluvial-linked systems. Within this broad area, two specific locations have been chosen that represent the northern limit of M. flexuosa current distribution. Time frame has been selected to allow: i) the comparison between intervals with and without human activity, and ii) covering the establishment of Mauritania which will allow a better understanding of the current trends (communities in expansion or reduction). The knowledge of past interactions between wetlands, seasonality changes and human practices will provide new insights into how this poorly understood community could face future projections of climatic and land use changes. In addition, emphasis will be placed on studying what influenced the composition of modern plant communities, to analyse their sensitivity to external drivers and to identify the occurrence of irreversible tipping points or thresholds in the recent past. The research will be addressed by using a combination of indicators (proxies) of past environmental change in sedimentary sequences, including: vegetation (pollen), erosion/run-off/sedimentation (palaeomagnetism, XRD), and human impacts (non-pollen palynomorphs, charcoal particles). Funding project reference: 2014 BP-B-00094.