Climatic oscillations stall vegetation recovery from K/Pg event devastation

Sedimentary rocks filling the Boltysh meteorite crater preserve an expanded record of post Cretaceous-Palaeogene (K/Pg) event vegetation destruction and subsequent floral recolonization. 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 characterized by low abundances of fern spores, whereas the overlying Phase 2 has high fern spore abundances and contains common palm pollen. Comparison of the Boltysh Phase 2 fern spore spike with other palynological records shows strong similarities to 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 define four moisture availability cycles between the K/Pg boundary and the Dan-C2 negative carbon isotope excursion, a period of some 300 kyr. 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.