Ecoclimatic Sensitivity in the Tropics to Last Glacial-Interglacial Climate Change via Data Mobilization in the Neotoma Paleoecology Database

Global networks of fossil pollen records retrieved from lakes and mires are the best data source for understanding past vegetation responses to climate change. Pollen data of the Neotoma Paleoecology Database, a community-curated paleoecology resource, historically were weighted towards temperate and high-latitude ecosystems in North America and Europe. However, recent data mobilization campaigns across the tropics now enable macro-scale analysis of tropical ecosystem dynamics since the Last Glacial Maximum (LGM). Better quantification of the ecoclimate sensitivity in the tropics is particularly critical, because of their high biodiversity, high carbon storage in rainforests, and positive feedbacks in carbon and water cycling.

Using Neotoma API services, we downloaded all pollen records from 23 thousand years BP (ka) to present between 25˚N and 25˚S. We selected data and temporal quality criteria, harmonized taxa lists using the new RFossilpol package (Flantua et al., in review) and recalibrated all age-depth models using the bchron R package. We obtained reconstructions of global surface air temperature (SAT) data at 1.9°×2.5° resolution from Tierney et al (2020) and bilinearly interpolated all SAT temperatures to site locations. We estimated ecoclimate sensitivity by calculating community turnover from the LGM to present, then regressing turnover against LGM-to-present temperature anomalies. We analyzed the spatiotemporal patterns in ecoclimate sensitivity through mixed effects models with elevation and temperature predictor variables.

The initial data retrieval from Neotoma yielded over 300 tropical records. We recalibrated age-depth models for 270 records and identified 73 records with at least one sample in the periods 5-2ka and 23-15ka. Initial results suggest a high community sensitivity of tropical ecosystems, particularly in montane regions. Variations among tropical regions in apparent climate sensitivity can be attributed to site factors such as elevational position and continentality. These results suggest that 21st-century climate scenarios with global temperature changes on the order of 4˚C will have substantial effects upon tropical plant distributions and community composition.