Swidden pollen spectra are unique, having no modern analogues

Abstract

O_LISlash-and-burn cultivation (SABC), a widespread premodern agricultural practice, shaped vegetation across the temperate zone of Eurasia for millennia, yet the SABC-associated plant communities and their modern analogues remain poorly understood. C_LIO_LIWe compared 74 fossil pollen spectra from radiocarbon-dated swidden horizons with 223 modern surface soil spectra using non-metric multidimensional scaling and cluster analysis. C_LIO_LIThe results show that slash-and-burn cultivation creates a unique palynological assemblage in soil, distinguishable from forests, meadows, fallows, and ruderal habitats. This signature was most pronounced in sites from broad-leaved coniferous forest, where cryptogam diversity was highest. C_LIO_LIHere, we report that pollen spectra from buried swidden soils across the Eastern European forest zone consistently form a distinct and cohesive cluster, lacking modern analogues. These spectra are characterized by high proportions of Betula, Tilia, Epilobium angustifolium, cereal pollen, and a diverse assemblage of spores (Marchantia, Lycopodium, Pteridium), reflecting a mosaic of post-cultivation successional stages. C_LIO_LIInsect activity, particularly pollen-storing burrows of ground-nesting bees, may enhance the swidden signal through selective accumulation of fireweed entomophilous pollen. C_LIO_LIOur results provide SABC reference pollen spectra for temperate mixed and deciduous forest zones and can be used as a tool for reconstructing the extinct suite of plant communities associated with swidden cultivation. C_LI