Editing Permian–Triassic extinction event (section)

=== Terrestrial plants ===
The proto-recovery of terrestrial floras took place from a few tens of thousands of years after the end-Permian extinction to around 350,000 years after it, with the exact timeline varying by region.<ref>{{cite journal |last1=Aftabuzzaman |first1=Md. |last2=Kaiho |first2=Kunio |last3=Biswas |first3=Raman Kumar |last4=Liu |first4=Yuqing |last5=Saito |first5=Ryosuke |last6=Tian |first6=Li |last7=Bhat |first7=Ghulam M. |last8=Chen |first8=Zhong-Qiang |date=October 2021 |title=End-Permian terrestrial disturbance followed by the complete plant devastation, and the vegetation proto-recovery in the earliest-Triassic recorded in coastal sea sediments |journal=[[Global and Planetary Change]] |volume=205 |page=103621 |doi=10.1016/j.gloplacha.2021.103621 |bibcode=2021GPC...20503621A |doi-access=free }}</ref> Furthermore, severe extinction pulses continued to occur after the Permian-Triassic boundary, causing additional floral turnovers.<ref>{{Cite journal |last1=Yang |first1=Wan |last2=Wan |first2=Mingli |last3=Crowley |first3=James L. |last4=Wang |first4=Jun |last5=Luo |first5=Xiaorong |last6=Tabor |first6=Neil |last7=Angielczyk |first7=Kenneth D. |last8=Gastaldo |first8=Robert |last9=Geissman |first9=John |last10=Liu |first10=Feng |last11=Roopnarine |first11=Peter |last12=Sidor |first12=Christian A. |date=November 2021 |title=Paleoenvironmental and paleoclimatic evolution and cyclo- and chrono-stratigraphy of upper Permian–Lower Triassic fluvial-lacustrine deposits in Bogda Mountains, NW China — Implications for diachronous plant evolution across the Permian–Triassic boundary |url=https://www.sciencedirect.com/science/article/abs/pii/S0012825221002427 |journal=[[Earth-Science Reviews]] |language=en |volume=222 |pages=103741 |doi=10.1016/j.earscirev.2021.103741 |bibcode=2021ESRv..22203741Y |access-date=13 October 2024 |via=Elsevier Science Direct}}</ref> Gymnosperms recovered within a few thousand years after the Permian-Triassic boundary, but around 500,000 years after it, the Dominant [[gymnosperm]] genera were replaced by [[Lycopodiophyta|lycophytes]]{{snd}}extant lycophytes are recolonizers of disturbed areas{{snd}}during an extinction pulse at the Griesbachian-[[Dienerian]] boundary.<ref name="Hochuli et al 2016">{{cite journal |last1=Hochuli |first1=Peter A. |last2=Sanson-Barrera |first2=Anna |last3=Schneebeli-Hermann |first3=Elke |last4=Bucher |first4=Hugo |title=Severest crisis overlooked—Worst disruption of terrestrial environments postdates the Permian–Triassic mass extinction |journal=[[Scientific Reports]] |date=24 June 2016 |volume=6 |issue=1 |pages=28372 |doi=10.1038/srep28372 |pmid=27340926 |pmc=4920029 |bibcode=2016NatSR...628372H }}</ref> The particular post-extinction dominance of lycophytes, which were well adapted for coastal environments, can be explained in part by global marine transgressions during the Early Triassic.<ref name="VajdaMcLoughlin2007">{{cite journal |last1=Vajda |first1=Vivi |last2=McLoughlin |first2=Stephen |date=April 2007 |title=Extinction and recovery patterns of the vegetation across the Cretaceous–Palaeogene boundary — a tool for unravelling the causes of the end-Permian mass-extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S0034666706001096 |journal=[[Review of Palaeobotany and Palynology]] |volume=144 |issue=1–2 |pages=99–112 |doi=10.1016/j.revpalbo.2005.09.007 |bibcode=2007RPaPa.144...99V |access-date=24 December 2022}}</ref> The worldwide recovery of gymnosperm forests took approximately 4–5&nbsp;million years.<ref>{{cite journal |author1=Looy, C. V. |author2=Brugman, W. A. |author3=Dilcher, D. L. |author4=Visscher, H. |year=1999 |title=The delayed resurgence of equatorial forests after the Permian–Triassic ecologic crisis |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=96 |issue=24 |pages=13857–13862 |bibcode=1999PNAS...9613857L |doi=10.1073/pnas.96.24.13857 |pmc=24155 |pmid=10570163 |doi-access=free}}</ref><ref name="McElwain2007" /> However, this trend of prolonged lycophyte dominance during the Early Triassic was not universal, as evidenced by the much more rapid recovery of gymnosperms in certain regions,<ref name="HochuliHermannVigranBucherWeissert2010" /> and floral recovery likely did not follow a congruent, globally universal trend but instead varied by region according to local environmental conditions.<ref name="FengEtAl2020EarthScience" />

In East Greenland, lycophytes replaced gymnosperms as the dominant plants. Later, other groups of gymnosperms again become dominant but again suffered major die-offs. These cyclical flora shifts occurred a few times over the course of the extinction period and afterward. These fluctuations of the dominant flora between woody and [[Herbaceous plant|herbaceous]] taxa indicate chronic environmental stress resulting in a loss of most large woodland plant species. The successions and extinctions of plant communities do not coincide with the shift in {{delta|13|C|link}} values but occurred many years after.<ref name="LooyEtAl2005EndPermianDeadZone" />

In what is now the Barents Sea of the coast of Norway, the post-extinction flora is dominated by pteridophytes and lycopods, which were suited for primary succession and recolonization of devastated areas, although gymnosperms made a rapid recovery, with the lycopod dominated flora not persisting across most of the Early Triassic as postulated in other regions.<ref name="HochuliHermannVigranBucherWeissert2010">{{cite journal |last1=Hochuli |first1=Peter A. |last2=Hermann |first2=Elke |last3=Vigran |first3=Jorunn Os |last4=Bucher |first4=Hugo |last5=Weissert |first5=Helmut |date=December 2010 |title=Rapid demise and recovery of plant ecosystems across the end-Permian extinction event |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818110002286 |journal=[[Global and Planetary Change]] |volume=74 |issue=3–4 |pages=144–155 |doi=10.1016/j.gloplacha.2010.10.004 |bibcode=2010GPC....74..144H |access-date=24 December 2022|url-access=subscription }}</ref>

In Europe and North China, the interval of recovery was dominated by the lycopsid ''Pleuromeia'', an opportunistic pioneer plant that filled ecological vacancies until other plants were able to expand out of refugia and recolonize the land. Conifers became common by the early Anisian, while pteridosperms and cycadophytes only fully recovered by the late Anisian.<ref>{{cite journal |last1=Grauvogel-Stamm |first1=Léa |last2=Ash |first2=Sidney R. |date=September–October 2005 |title=Recovery of the Triassic land flora from the end-Permian life crisis |url=https://www.sciencedirect.com/science/article/pii/S1631068305000813 |journal=[[Comptes Rendus Palevol]] |volume=4 |issue=6–7 |pages=593–608 |doi=10.1016/j.crpv.2005.07.002 |bibcode=2005CRPal...4..593G |access-date=24 December 2022|url-access=subscription }}</ref>

During the survival phase in the terrestrial extinction's immediate aftermath, from the latest Changhsingian to the Griesbachian, South China was dominated by opportunistic lycophytes.<ref name="EndPermianMiddleTriassicPlantSpeciesRichness">{{cite journal |last1=Xu |first1=Zhen |last2=Hilton |first2=Jason |last3=Yu |first3=Jianxin |last4=Wignall |first4=Paul Barry |last5=Yin |first5=Hongfu |last6=Xue |first6=Qing |last7=Ran |first7=Weiju |last8=Li |first8=Hui |last9=Shen |first9=Jun |last10=Meng |first10=Fansong |date=September 2022 |title=End Permian to Middle Triassic plant species richness and abundance patterns in South China: Coevolution of plants and the environment through the Permian–Triassic transition |url=https://www.sciencedirect.com/science/article/abs/pii/S0012825222002203 |journal=[[Earth-Science Reviews]] |volume=232 |page=104136 |doi=10.1016/j.earscirev.2022.104136 |bibcode=2022ESRv..23204136X |s2cid=251031028 |archive-url=https://web.archive.org/web/20230114081510/https://www.sciencedirect.com/science/article/abs/pii/S0012825222002203 |archive-date=14 January 2023 |access-date=26 June 2023 |url-status=bot: unknown }}</ref> Low-lying herbaceous vegetation dominated by the isoetalean ''[[Tomiostrobus]]'' was ubiquitous following the collapse of the gigantopterid-dominated forests of before. In contrast to the highly biodiverse gigantopterid rainforests, the post-extinction landscape of South China was near-barren and had vastly lower diversity.<ref name="FengEtAl2020EarthScience">{{Cite journal |last1=Feng |first1=Zhuo |last2=Wei |first2=Hai-Bo |last3=Guo |first3=Yun |last4=He |first4=Xiao-Yuan |last5=Sui |first5=Qun |last6=Zhou |first6=Yu |last7=Liu |first7=Hang-Yu |last8=Gou |first8=Xu-Dong |last9=Lv |first9=Yong |date=May 2020 |title=From rainforest to herbland: New insights into land plant responses to the end-Permian mass extinction |journal=[[Earth-Science Reviews]] |language=en |volume=204 |pages=103153 |doi=10.1016/j.earscirev.2020.103153|bibcode=2020ESRv..20403153F |s2cid=216433847 |doi-access=free }}</ref> Plant survivors of the PTME in South China experienced extremely high rates of mutagenesis induced by heavy metal poisoning.<ref name="MetalStress" /> From the late Griesbachian to the Smithian, conifers and ferns began to rediversify. After the Smithian, the opportunistic lycophyte flora declined, as the newly radiating conifer and fern species permanently replaced them as the dominant components of South China's flora.<ref name="EndPermianMiddleTriassicPlantSpeciesRichness" />

On the Tibetan plateau, China, the early Dienerian ''Endosporites papillatus''–''Pinuspollenites thoracatus'' assemblages closely resemble late Changhsingian Tibetan floras, suggesting that the widespread, dominant latest Permian flora repopulated easily after the PTME. However, in the late Dienerian, a major shift towards assemblages dominated by cavate trilete spores took place, heralding widespread deforestation and a rapid change to hotter, more humid conditions. Quillworts and spike mosses dominated Tibetan flora for about a million years after this shift.<ref>{{cite journal |last1=Liu |first1=Feng |last2=Peng |first2=Huiping |last3=Bomfleur |first3=Benjamin |last4=Kerp |first4=Hans |last5=Zhu |first5=Huaicheng |last6=Shen |first6=Shuzhong |date=October 2020 |title=Palynology and vegetation dynamics across the Permian–Triassic boundary in southern Tibet |journal=[[Earth-Science Reviews]] |volume=209 |page=103278 |doi=10.1016/j.earscirev.2020.103278 |bibcode=2020ESRv..20903278L |s2cid=225585090 |doi-access=free }}</ref>

In Pakistan, then the northern margin of Gondwana, the flora was rich in lycopods associated with conifers and pteridosperms. Floral turnovers continued to occur due to repeated perturbations arising from recurrent volcanic activity until terrestrial ecosystems stabilized around 2.1 Myr after the PTME.<ref>{{cite journal |last1=Hermann |first1=Elke |last2=Hochuli |first2=Peter A. |last3=Bucher |first3=Hugo |last4=Brühwiler |first4=Thomas |last5=Hautmann |first5=Michael |last6=Ware |first6=David |last7=Roohi |first7=Ghazala |date=September 2011 |title=Terrestrial ecosystems on North Gondwana following the end-Permian mass extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S1342937X1100030X |journal=[[Gondwana Research]] |volume=20 |issue=2–3 |pages=630–637 |doi=10.1016/j.gr.2011.01.008 |bibcode=2011GondR..20..630H |access-date=31 May 2023|url-access=subscription }}</ref>

In southwestern Gondwana, the post-extinction flora was dominated by bennettitaleans and cycads, with members of [[Peltaspermales]], [[Ginkgoales]], and Umkomasiales being less common constituents of this flora. Around the Induan-Olenekian boundary, as paleocommunities recovered, a new ''Dicroidium'' flora was established, in which Umkomasiales continued to be prominent and in which Equisetales and Cycadales were subordinate forms. The ''Dicroidium'' flora further diversified in the Anisian to its peak, wherein Umkomasiales and Ginkgoales constituted most of the tree canopy and Peltaspermales, Petriellales, Cycadales, Umkomasiales, Gnetales, [[Equisetales]], and Dipteridaceae dominated the undergrowth.<ref name="JosefinaBodnar">{{cite journal |last1=Bodnar |first1=Josefina |last2=Coturel |first2=Eliana P. |last3=Falco |first3=Juan Ignacio |last4=Beltrána |first4=Marisol |date=4 March 2021 |title=An updated scenario for the end-Permian crisis and the recovery of Triassic land flora in Argentina |url=https://www.tandfonline.com/doi/abs/10.1080/08912963.2021.1884245 |journal=[[Historical Biology]] |volume=33 |issue=12 |pages=3654–3672 |doi=10.1080/08912963.2021.1884245 |bibcode=2021HBio...33.3654B |s2cid=233810158 |access-date=24 December 2022|url-access=subscription }}</ref>

==== Coal gap{{anchor|Coal Gap}} ====
No [[coal]] deposits are known from the Early Triassic, and those in the Middle Triassic are thin and low-grade. This "coal gap" has been explained in many ways. It has been suggested that new, more aggressive fungi, insects, and vertebrates evolved and killed vast numbers of trees. These [[decomposer]]s themselves suffered heavy losses of species during the extinction and are not considered a likely cause of the coal gap. It could simply be that all coal-forming plants were rendered extinct by the P–Tr extinction and that it took 10&nbsp;million years for a new suite of plants to adapt to the moist, acid conditions of [[peat]] [[bogs]].<ref name="Retallack1996" /> [[Abiotic]] factors (factors not caused by [[organism]]s), such as decreased rainfall or increased input of [[Clastic rock|clastic sediments]], may also be to blame.<ref name="McElwain2007" />

On the other hand, the lack of coal may simply reflect the scarcity of all known [[sediment]]s from the Early Triassic. Coal-producing [[ecosystem]]s, rather than disappearing, may have moved to areas where we have no sedimentary record for the Early Triassic.<ref name="McElwain2007" /> For example, in eastern Australia a cold climate had been the norm for a long period, with a peat [[Bog|mire]] ecosystem adapted to these conditions.<ref>{{cite journal |last1=Retallack |first1=Gregory J. |date=1 January 1999 |title=Postapocalyptic greenhouse paleoclimate revealed by earliest Triassic paleosols in the Sydney Basin, Australia |url=https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/111/1/52/183439/Postapocalyptic-greenhouse-paleoclimate-revealed |journal=[[Geological Society of America Bulletin]] |volume=111 |issue=1 |pages=52–70 |doi=10.1130/0016-7606(1999)111<0052:PGPRBE>2.3.CO;2 |access-date=31 May 2023|url-access=subscription }}</ref> Approximately 95% of these peat-producing plants went ''locally'' extinct at the P–Tr boundary;<ref>{{cite journal |last=Michaelsen |first=P. |year=2002 |title=Mass extinction of peat-forming plants and the effect on fluvial styles across the Permian–Triassic boundary, northern Bowen Basin, Australia |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=179 |issue=3–4 |pages=173–188 |bibcode=2002PPP...179..173M |doi=10.1016/S0031-0182(01)00413-8}}</ref> coal deposits in Australia and Antarctica disappear significantly ''before'' the P–Tr boundary.<ref name="McElwain2007" />