Challenge-based citizen science Citizen science and trees Issue: how to model spread (and impact) of tree disease Why?: for better modelling of spread = risk-based monitoring & management interventions Link to Defra report Professional and/or citizen science Problem: we don’t precisely know where our trees are Link to Fera report Tree ID algorithms We know precisely where trees are – but not which species We know roughly where species are Link to CS report Earth observation Modelling improvements A solution? Proposed: A citizen science hunt for trees – targeted to improve tree id algorithms Crowd-source ground truthing? Challenge-based citizen science Large-scale We know precisely where species are in a few locations We know precisely where woods are – and their composition michael.pocock@ceh.ac.uk | @mjopocock