DYNAMICS OF ABRUPT CHANGE IN TROPICAL AFRICAN FORESTS (Invited Presentation)

Tropical forests provide essential resources, including food, fuel, and medicine, to millions of people in Africa as well as having links to ecosystem services that include fisheries and freshwater. Changes in climate and land use have already resulted in decreased forest extent. Abrupt changes in ecosystems have the potential to occur on human timescales. Although paleoecological data is well suited to answering questions about the timing and pace of vegetation change, detecting spatial patterns requires a network of sites that is often inaccessible. Until recently, data availability in Africa was too limited to evaluate tipping points in Afrotropical forests that would strain adaptive capacity in this region.

However, recent advances in paleoenvironmental data acquisition through scientific drilling and other coring methods along with increases in legacy data standardization following FAIR data principles has made it possible to pose scientific questions about past ecosystem change that were previously not possible. In order to this, the African Pollen Database (APD) has recently been relaunched as a constituent database within the Neotoma Paleoecology Database. We use recently standardized APD data along with newly developed open-access tools to retrieve and manipulate pollen data from Neotoma (neotoma2) and to identify abrupt change events (actR) since the Last Glacial Maximum (21ka).

We observe clusters of rapid vegetation change at the continental-scale during the last deglaciation as well as within the last 4000 years. During the last deglaciation, tropical ecosystem responses to changes in rainfall showed a complex spatial structure resembling the north-south hinge-point in tropical rainfall across Africa. In contrast, forest decrease followed by rapid transition to savanna occurred throughout Africa during the late Holocene, despite modest and heterogenous changes in climate. This spatial and temporal pattern suggests a response to changes in rainfall coupled with human expansion and technological development over that period. This work suggests that tropical forests as a phytogeographic region have changed rapidly in the past, thus identifying tipping points is important for managing and mitigating changes to resources in developing countries over the coming decades.