Late-Quaternary spatiotemporal dynamics of vegetation in Central Mexico

Abstract

Central Mexico exhibits a complex environment with wide topographic, climatic, and biological gradients. Lacustrine basins distributed along the region have been the source for numerous paleoenvironmental reconstructions, representing an exceptional opportunity for studying vegetation turnover dynamics across time and space. A total of 1397 fossil and modern pollen samples were ordinated through a Detrended Correspondence Analysis (DCA) to characterize the regional ecological space. Resulting DCA Axis 1 scores were related to a forest cover gradient. Aiming to generalize the interpretation of the analyzed records and given the clear altitudinal pattern shown by modern samples, paleoenvironmental interpretations were performed grouping fossil records according to their elevation. Euclidean distances among sites scores were used as estimators of ecological distance and summarized from two different approaches to observe turnover dynamics at different spatial scales: i) local turnover through time, and ii) ecological versus geographic distance. The regional late Quaternary vegetation dynamics were found mostly driven by global climatic events, whereas the Holocene was marked by more local factors such as precipitation regime and human occupation patterns. Strong local modulation in turnover dynamics was observed in the region. Additionally, we conclude that a palynological record produces results that are repeatable within 50km, considering a maximum compositional turnover of 50%.