Contributions of Quaternary botany to modern ecology and biogeography

Quaternary (last 2.6 million years) botany involves studying plant megafossils (e.g. tree stumps), macrofossils (e.g. seeds, leaves), and microfossils (e.g. pollen, spores) preserved in peat bogs and lake sediments. Although megafossils and macrofossils have been studied since the late eighteenth century, Quaternary botany today is largely dominated by pollen analysis. Quaternary pollen analysis is just over 100 years old. It started primarily as a geological tool for correlation, relative dating, and climate reconstruction. In 1950 a major advance occurred with the publication by Knut Faegri and Johs Iversen of their Text-book of Modern Pollen Analysis which provided the foundations for pollen analysis as a botanical and ecological tool for studying past dynamics of biota and biotic systems. The development of radiocarbon dating in the 1950s freed pollen analysis from being a tool for relative dating. As a result of these developments, pollen analysis became a valuable implement in long-term ecology and biogeography. Selected contributions that Quaternary botany has made to ecology and biogeography since 1950 are reviewed. They fall into four general parts: (1) ecological aspects of interglacial and glacial stages such as location and nature of glacial-stage tree refugia and long-term soil development in glaciated and unglaciated areas; (2) biotic responses to Quaternary environmental change (spreading, extinction, persistence, adaptation); (3) ecological topics such as potential niches, the nature of vegetation, and tree and forest dynamics; and (4) its application to ecological topics such as human impact in tropical systems, conservation in a changing world, island palaeoecology, plant-animal interactions, and biodiversity patterns in time. The future of Quaternary botany is briefly discussed and 10 suggestions are presented to help strengthen it and its links with ecology and biogeography. Quaternary botany has much to contribute to ecology and biogeography when used in conjunction with new approaches such as ancient-DNA, molecular biomarkers, and multi-proxy palaeoecology.