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Soils are a crucial link between the atmosphere, biosphere, and geosphere. Any disturbance to the health of soils will severely impact plants as well as a multitude of organisms living in or on soils, such as fungi, bacteria, and insects. Catastrophic soil loss is thought to have played a pivotal role during mass-extinction events as a result of major deforestation, but the exact feedbacks remain elusive. Here, we assess the role of soil loss during the end-Triassic mass-extinction event based on proxy data obtained from four sediment sections recovered from France, Germany, and Denmark. Clay mineral and palynological data indicate a strong increase in erosion during the latest Rhaetian with the influx of kaolinite and abundantly reworked Palaeozoic and Neoproterozoic organic matter. Based on a new timeline, these changes were coeval with intense volcanic activity in the Central Atlantic Magmatic Province (CAMP). In addition to vegetation dieback, repeated forest fires, as well as widespread seismic activity related to CAMP emplacement led to landscape destruction triggering removal of soils. The biological degradation of fern spore walls by fungi and bacteria, a process coupled to organic matter decay in soils, strongly decreased across the T/J boundary. We interpret this counter-intuitive result as evidence for rapid and widespread removal of soils. Taken together, CAMP induced environmental changes led to profound changes in erosion and removal of soils, while soil resilience during the Hettangian appears to have proceeded hand in hand with recovery in Jurassic seas. [ABSTRACT FROM AUTHOR]

The end-Triassic mass extinction event (∼201.4 million years ago) caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the Triassic-Jurassic (T-J) boundary caused by massive release of carbon dioxide and/or methane related to extensive volcanism in the Central Atlantic Magmatic Province (CAMP), resulting in a more humid climate with increased storminess and lightning activity. Lightning strikes are considered the primary source of wildfires, producing charcoal, microscopically recognized as inertinite macerals. The presence of polycyclic aromatic hydrocarbons (PAHs) of pyrolytic origin and allochthonous charcoal in siliciclastic T-J boundary strata has suggested widespread wildfire activity at the time. We have investigated largely autochthonous coal and coaly beds across the T-J boundary in Sweden and Denmark. These beds consist of predominantly organic material from the in situ vegetation in the mires, and as the coaly beds represent a substantial period of time they are excellent environmental archives. We document a remarkable increase in inertinite content in the coal and coaly beds across the T-J boundary. We show estimated burning temperatures derived from inertinite reflectance measurements coupled with palynological data and conclude that pre-boundary late Rhaetian mire wildfires included high-temperature crown fires, whereas latest Rhaetian-Sinemurian mire wildfires were more frequent but dominated by lower temperature surface fires. Our results suggest a major change in the mire ecosystems across the T-J boundary from forested, conifer dominated mires to mires with a predominantly herbaceous and shrubby vegetation. Contrary to the overall regional vegetation for which onset of recovery commenced in the early Hettangian, the sensitive mire ecosystem remained affected during the Hettangian and did not start to recover until around the Hettangian-Sinemurian boundary. Decreasing inertinite content through the Lower Jurassic suggests that fire activity gradually resumed to considerable lower levels.