Rapid (10-yr) recovery of terrestrial productivity in a simulation study of the terminal Cretaceous impact event

Investigations of short-term (up to 10(3) yr) environmental change across t he Cretaceous-Tertiary boundary provide evidence for reduced temperatures, consistent with the injection of debris and sulphate. aerosols into the upp er atmosphere by a large impact event. Concomitant with this was a postulat ed massive addition Of CO2 to the atmospheric carbon reservoir by impact va porisation of the Chicxulub carbonate platform. Taken together, a high CO2 but low irradiance environment would have created unusual conditions for th e operation of the terrestrial biosphere. Here, we have evaluated this envi ronmental influence on terrestrial ecosystems using a process-based dynamic global vegetation model forced with post-impact global climates, derived b y modification of the GENESIS atmospheric climate model simulation for the latest Cretaceous. Our results suggest that terrestrial primary prod-activi ty initially collapsed and then recovered to pre-impact levels within a dec ade. Global terrestrial carbon storage in vegetation biomass exhibited a si milar collapse but complete recovery took place on a 60-80 yr timescale. Th e recovery of both terrestrial net primary productivity and vegetation biom ass was largely mediated by the high CO2 concentration stimulating ecosyste m photosynthetic productivity in the warm low latitudes. An apparently rapi d recovery of terrestrial ecosystem function stands in marked contrast to t he situation for the marine realm, where the organic carbon flux to the dee p ocean was suppressed for up to 3 million years. (C) 2001 Elsevier Science B.V. All rights reserved.