Climatic oscillations stall vegetation recovery from K/Pg event devastation

Sedimentary rocks filling the Boltysh meteorite crater preserve an expanded record of post K/Pg event vegetation destruction and subsequent floral recolonisation. A post-destruction barren zone is succeeded by a fern spore spike recording the initial recovery vegetation. The Boltysh fern spore spike is divisible into two phases. Phase 1 is characterised by low abundances of fern spores of the Polypodicaeae and Pteridaceae, while the overlying Phase 2 has high fern spore abundances and contains common palm pollen. Comparison of the Boltysh Phase 2 fern spore spike to other palynological records show strong similarities with the immediately post K/Pg boundary record of the Western Interior, North America. Variation in the composition of the Boltysh palynofloras has been used to defined four moisture availability cycles between the K/Pg boundary and Dan-C2. Time constraints consequent on these events indicate that early post K/Pg event vegetation community recovery followed a common seral successional pathway at rates seen in Large Igneous Provinces, although enhanced by high moisture availability. Continued succession to the first true swamp community was at a considerably slower tempo. The post K/Pg event vegetation recovery was therefore retarded by lack of moisture availability, extending the apparent period of recovery. Without this moisture availability oscillation, recovery to the first mature communities could have occurred at similar rates to those seen in Large Igneous Provinces