The origin of collapse features appearing in a migrating parabolic dune along the southern coast of Lake Michigan

•We present a model explaining the formation of temporarily stable voids in migrating dune systems.•Saprotrophic wood decay fungi biomineralize a cement at contact between organic material and sand.•The voids are found in a migrating dune where the modern trees were buried for less than 100years.•The dune decomposition chimneys provide a modern analog for tree casts observed in lithified dunes.