Pleistocene megafaunal extinction in the grasslands of Junín‐Peru.

Aim: To determine the timing of megafaunal extinction in the high plains of Peru and also to determine if the timing was delayed in grasslands compared with previously published forested settings to dissociate the effects of succession from human or climatic impacts. Location: The Junín Plateau, Peru. Taxon: Flowering plants and Ascomycetes. Methods: The sediments used in this analysis were collected from the edge of Lake Junín, Peru. Eleven ages derived from 14C accelerator mass spectrometry provide a chronology. We provide a paleoecological reconstruction of past climate and vegetation change, fire history and megafaunal herbivore presence from c. 20,000–7000 years ago based on fossil pollen, charcoal and Sporormiella spores. Data were analysed using multivariate analysis and Bayesian change point analysis. Results: Megafaunal populations appear to have been positively impacted by dry climatic oscillations until c. 15,200 years ago. A reduction in Sporormiella abundance between 13,000 and 12,300 years before the present coincides with increased charcoal abundance and is identified as the period of megafaunal population collapse leading to extinction. The timing of the extinction does not differ substantially from that observed in wooded Andean settings. Main Conclusion: The timing of the collapse of megafaunal populations in high grasslands was very similar to that of lower, now‐forested settings. Upticks in fire activity, during what is generally seen to be a wet period, formed the backdrop to extinction and are strongly associated with human activity. [ABSTRACT FROM AUTHOR]