Holocene records of <i>Kretzschmaria deusta</i> : Ecological implications of a wood parasite in European landscapes

Kretzschmaria deusta is a wood-parasitic ascomycete affecting a range of broadleaf trees in temperate regions, including Europe, causing wood decay. Its ascospores, as an example of Non-Pollen Palynomorphs (NPPs), are preserved in Quaternary sediments, providing a rare record of past host-pathogen associations. This study synthesizes the Holocene palaeoecological record of Kretzschmaria deusta , examining its spatial and temporal distribution, host preferences, and ecological impacts. Early Holocene occurrences are sparse in Europe, whereas Middle and Late-Holocene spores indicate widespread presence, coinciding with the expansion of deciduous forests. Throughout the Holocene, Kretzschmaria deusta acts primarily as an opportunistic pathogen, exploiting trees weakened by natural and anthropogenic factors. Elevated spore abundances may reflect periods of increased tree damage rather than primary forest decline. Host responses vary among taxa. Tilia tolerates repeated infection, whereas Fagus , Abies , and Ulmus are more sensitive, with higher fungal abundances corresponding to possible host decline. Warm temperatures during the Holocene further facilitated fungal growth and infection success. The predominantly local dispersal of spores suggests that this NPP record reflects nearby woodland conditions, although episodic transport by wind or water may cause temporary increases. The Holocene findings of Kretzschmaria deusta enhances our understanding of long-term tree-fungus associations and highlights the potential role of this fungus in forest decline under future warming and intensified anthropogenic pressure.