Introduction to the special issue: Pollen diversity, vegetation history and range shift in the (sub)tropics through the Cenozoic

Abstract

Fossil pollen records are valuable for reconstructing past floristic composition, vegetation and biogeographic history. In recent decades, a deeper understanding of plant diversity throughout the Cenozoic has been achieved, significantly due to improved taxonomic resolution of palynological data, particularly in the (sub)tropics, where pollen diversity is notably high. Particularly, the development of pollen databases and innovative techniques in systematic palynology has shed further light on our understanding of pollen diversity, vegetation history and range shift in the past, as well as the factors driving these changes. This special issue compiles the latest studies on 1) systematic palynology, highlighting updated methodologies such as high-resolution microscopy, machine learning, and chemotaxonomy, 2) long-term vegetation history and 3) spatio-temporal range shift mainly focusing on the (sub)tropics, encompassing change rate of dynamic vegetation in global or regional scales, human impacts, range shift of ecologically-important tree taxa through the Cenozoic based on fossil pollen records and/or molecular data.

This special issue features fourteen papers that explore pollen diversity, vegetation history and range shift in the (sub)tropics throughout the Cenozoic, categorized into five areas: (1) Pollen diversity: ranging from traditional morphological studies to chemical analyses of sporopollenin and applications of machine learning; (2) Outreach and education initiatives involving 3D printing of pollen grains; (3) Applications of fossil pollen records: including their significance for reconstructing palaeoclimate, palaeobiogeography and palynostratigraphy; (4) Challenges in pollen counting within Quaternary pollen analysis; and (5) Vegetation history and plant range shift. Future palynological studies should further focus on chemonotaxonomy, sedimentary ancient DNA (sedaDNA), and the application of machine leaning to both modern and fossil pollen analyses.