Evaluating Ustulina deusta as a proxy for the impact of Neolithic woodland management at the mid-Holocene Elm Decline in Britain

The mid-Holocene decline in elm ( Ulmus ) pollen frequencies is perhaps the most debated and researched pollen-analytical feature of vegetation history in northwest Europe, with various causes or combination of causes proposed to explain it. It has a significant radiocarbon age range in Britain, but its timing in the early stages of Neolithic settlement suggests that subsistence farming activities probably played a role as well as factors such as disease and climate change. With these variables unproven, we have investigated ascospores of the wood-rot fungus Ustulina deusta as an independent proxy indicator of elm tree mortality, as the distinctive spores are often stratified in Elm Decline levels. Inspection of 20 sites in north Britain shows the distinct association of U. deusta with the Elm Decline, although with considerable variation between sites in the amplitude and shape of the U. deusta curve across the Elm Decline levels. U. deusta relies for successful infection on physically damaged trees, and we contend that girdling of elms by early Neolithic farmers to provide clearings for cereal cultivation and cattle grazing provided the conditions for U. deusta infection. Curves for Plantago lanceolata and Sporormiella , other indicators of herbivore presence, mirror the U. deusta curve, supporting this hypothesis. We conclude that the behaviour of the U. deusta curve at the Elm Decline supports early Neolithic animal husbandry and woodland manipulation as a primary cause of the mid-Holocene fall in elm populations.