Approximately 252 million years ago, Earth experienced the most severe biotic crisis of the Phanerozoic at the Permian–Triassic transition, resulting in profound disruptions to both marine and terrestrial ecosystems. Extensive geological evidence has linked this global crisis to large-scale magmatism, particularly the Siberian Traps Large Igneous Province and associated volcanic activity in the Tethyan realm. However, how volcanic activity at different stages influenced terrestrial ecosystems through successive environmental processes, and whether terrestrial ecosystems at different latitudes responded synchronously, remain poorly understood within high-resolution chronological frameworks.
Recently, an international research team led by Professor Hua Zhang of the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, published a study in Earth and Planetary Science Letters. The researchers investigated the South Taodonggou (STDG) terrestrial section in Northwest China, which represents a mid-latitude setting at the Permian–Triassic transition. Combining a high-resolution chronological framework with multiproxy geochemical, wildfire, and paleontological records, the team reconstructed the environmental and ecological evolution of mid-latitude terrestrial ecosystems during the end-Permian crisis.
The study shows that the end-Permian terrestrial crisis at mid-latitudes was not triggered by a single, instantaneous environmental stress. Instead, it developed through a sequence of successive environmental perturbations, characterized by a transition from intensified surface wildfires to subsurface volcanic pyrolysis, ultimately contributing to terrestrial ecosystem collapse and reorganization.
The study reveals: 1. Volcanism initiated the mid-latitude terrestrial environmental crisis at ~252.165 Ma, while ecosystem responses differed among latitudes
The research team used high-resolution mercury (Hg) records to trace the environmental influence of volcanic activity. The results show that terrestrial environmental deterioration in the Northern Hemisphere mid-latitudes began at approximately 252.165 Ma, accompanied by pronounced Hg enrichment, a negative carbon-isotope excursion, and a decline in terrestrial organic carbon accumulation.
The temporal coincidence of Hg enrichment and carbon-cycle perturbation within the uncertainty of the age model indicates enhanced volcanic input and associated disruption of the global carbon cycle during this interval. These findings provide important chronological evidence linking volcanism with the onset of terrestrial environmental deterioration.
The high-resolution age framework further reveals that the collapse of mid-latitude forest ecosystems preceded the final collapse of tropical rainforest ecosystems by approximately 300 kyr. This asynchronous pattern indicates that terrestrial ecosystems did not collapse simultaneously worldwide. Instead, the end-Permian terrestrial crisis exhibited pronounced spatial and temporal heterogeneity, potentially reflecting differences in wildfire activity, hydroclimate conditions, vegetation composition, and the timing and distribution of volcanic disturbances.
2. Mid-latitude forests experienced severe wildfire disturbance during the early phase of the crisis
During the early phase of environmental deterioration, charcoal abundance and combustion-derived polycyclic aromatic hydrocarbons (PAHs) increased substantially, indicating enhanced landscape-scale wildfire activity. Combined with previously documented palynological and plant-fossil evidence, these records suggest that environmental stress during this interval was closely associated with the decline of mid-latitude gymnosperm-dominated forests.
The intensified wildfire activity likely represented an important disturbance mechanism affecting terrestrial ecosystems during the early stage of the end-Permian crisis. However, wildfire activity did not persist throughout the entire crisis interval.
During the Early Triassic, charcoal abundance declined markedly, indicating a reduction in large-scale combustion of surface vegetation. Meanwhile, a distinct high-temperature combustion-related geochemical signal emerged, suggesting a fundamental shift in the dominant combustion process affecting terrestrial environments.
3. A transition from surface burning to subsurface volcanic pyrolysis
The researchers identified a distinct combustion signal in charcoal-poor Early Triassic sediments. These deposits contain anomalously high concentrations of thermally generated PAHs, accompanied by exceptionally high fluoranthene/pyrene ratios.
Unlike typical signatures produced by surface wildfires, these geochemical characteristics are more consistent with high-temperature thermal alteration of buried organic matter. The results suggest that combustion-related processes shifted from surface biomass burning during the early crisis phase to subsurface pyrolysis of sedimentary organic carbon during the later stage.
The researchers propose that intrusive magmatism associated with large igneous province activity may have provided a prolonged heat source for this process. When magma intruded into organic-rich sedimentary basins, sustained heating could have caused buried peat, coal, and dispersed organic matter to undergo high-temperature pyrolysis, releasing thermally generated compounds and producing geochemical signals distinct from those associated with landscape fires.
This mechanism is consistent with previously proposed volcanic combustion and pyrolysis models from regions such as the Tunguska Basin of Siberia and South China. However, the continuous, high-resolution, and age-constrained record from the STDG section provides new constraints on the temporal succession between wildfire activity and subsurface thermal alteration.
The findings indicate that as volcanic activity and its thermal effects evolved, terrestrial combustion processes may have transitioned from early surface biomass burning to later subsurface volcanic pyrolysis. Therefore, the environmental impacts of volcanism may have extended beyond volcanic eruptions and atmospheric emissions, involving a prolonged pathway of: magma intrusion → heating of sedimentary organic matter → subsurface pyrolysis → release of thermally generated compounds. This process may have provided a sustained source of environmental stress during the recovery interval.
4. Sequential environmental stress prolonged the terrestrial crisis and ecosystem reorganization
By integrating combustion, weathering, and paleontological records, the researchers reconstructed a sequence of environmental and ecological changes extending from the initial wildfire phase into the Early Triassic.
The transition from intensified surface wildfires to subsurface pyrolysis was accompanied by changes in weathering regimes and major reorganizations of terrestrial biota. Plant communities underwent substantial turnover, while terrestrial vertebrate communities experienced major restructuring, including the decline of Permian dicynodonts and the subsequent appearance and expansion of the stress-tolerant herbivore Lystrosaurus.
Together, these observations suggest that the terrestrial crisis was not simply a short-lived episode of widespread fire. Instead, it developed through a sequence of interacting processes: volcanic forcing → carbon-cycle perturbation → wildfire intensification → vegetation loss and environmental degradation → subsurface volcanic pyrolysis → prolonged ecosystem reorganization.
The researchers suggest that continued intrusive heating may have contributed to the delayed recovery of terrestrial ecosystems. Thus, even after large-scale surface wildfires diminished, terrestrial environments may have remained exposed to persistent thermal and geochemical disturbances associated with intrusive magmatism, potentially prolonging ecological stress and delaying recovery.
Overall, this study reveals a stage-dependent structure of the end-Permian terrestrial crisis. Different phases of volcanic activity generated distinct environmental pressures, which interacted with ecosystem vulnerability and feedbacks to drive terrestrial ecosystem collapse and reorganization.
The high-resolution record from Northwest China provides new geological evidence that deep Earth volcanic processes can influence terrestrial ecosystems through both surface and subsurface pathways. It also demonstrates that terrestrial ecosystem collapse during global environmental crises may occur asynchronously across latitudes, reflecting complex interactions among volcanism, climate change, wildfire dynamics, and ecosystem resilience.
The findings emphasize that understanding the environmental consequences of large igneous provinces requires consideration of both eruptive and intrusive magmatism, as well as their potentially different effects on terrestrial ecosystems. They also demonstrate that terrestrial mass extinction may unfold as a prolonged and spatially heterogeneous process, in which successive environmental stressors interact with the intrinsic vulnerability of different biomes.
This study provides new geological evidence for understanding how large igneous province activity can drive terrestrial ecosystem crises through successive surface and subsurface processes, and how terrestrial ecosystems at different latitudes may respond differently to global environmental change.
Professor Hua Zhang led the study. PhD student Shenglin Jiao and Assistant Researcher Yaofeng Cai of the Nanjing Institute of Geology and Palaeontology are co-first authors. Other members of the research team include Professor Wan Yang of Missouri University of Science and Technology, Professor Mingli Wan of the Nanjing Institute of Geology and Palaeontology, and Professor Shuzhong Shen, an Academician of the Chinese Academy of Sciences at Nanjing University.
The study was supported by projects funded by the National Natural Science Foundation of China, the National Key Research and Development Program of China, the Jiangsu Innovation Support Plan for International Science and Technology Cooperation Program, and the U.S. National Science Foundation.
Reference: Jiao, S.L.#, Cai, Y.F.#, Yang, W., Wan, M.L., Shen, S.Z., Zhang, H.*, 2026. Succession of environmental stressors from wildfires to volcanic pyrolysis drove mid-latitude terrestrial ecosystem collapse during the end-Permian crisis. Earth Planet. Sci. Lett. 695, 120319. https://doi.org/10.1016/j.epsl.2026.120319.
Fig.1 High-resolution, age-calibrated proxy records of environmental change and terrestrial ecosystem collapse across the Permian–Triassic transition.
Fig.2 Comparative synthesis of the end-Permian terrestrial crisis across paleolatitudes.
Fig.3 Paleoecological reconstructions of terrestrial ecosystems from the Lopingian to Early Triassic based on fossil records, wildfires, climatic conditions, and sedimentological evidence from the STDG section.
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