A fossilised forest comprising of fossil trees (known as Calamophyton), and vegetation-induced sedimentary structures has been discovered in the high sandstone cliffs along the Devon and Somerset coast of Southwest England. This dates from 390 million years ago which makes it the oldest known fossil forest on ແຜ່ນດິນໂລກ.
One of the key events in the history of ແຜ່ນດິນໂລກ is afforestation or transition to forested ດາວ following evolution of trees and forests in the Mid–Late Devonian Period, 393–359 million years ago. The tree sized vegetations fundamentally changed the land biosphere in terms of stabilisation of sediments on flood plains, clay mineral production, weathering rates, CO2 drawdown, and the hydrological cycle. These changes had profound impact on the future of ແຜ່ນດິນໂລກ.
ຕົ້ນຟອດຊິວທໍາອິດສະລະທີ່ທໍາອິດເປັນຂອງ Cladoxylopsida ພັດທະນາໃນຕົ້ນ Mid-Devonian. ໄດ້ ຕົ້ນໄມ້ cladoxylopsid (calamophyton) ແມ່ນ ມີເນື້ອໄມ້ໜ້ອຍກວ່າເມື່ອທຽບໃສ່ກັບຕົ້ນ lignophytes archaeopteridalean (archaeopteris) ທີ່ພັດທະນາຕໍ່ມາໃນທ້າຍ Mid-Devonian. ຈາກທ້າຍກາງ-Devonian, ຕົ້ນໄມ້ lignophytes flora ເລີ່ມຕົ້ນຄອບງໍາທີ່ດິນ ( lignophytes ແມ່ນພືດ vascular ທີ່ຜະລິດໄມ້ທີ່ເຂັ້ມແຂງໂດຍຜ່ານ cambium).
ໃນການສຶກສາທີ່ຜ່ານມາ, ນັກຄົ້ນຄວ້າໄດ້ກໍານົດພູມສັນຖານປ່າໄມ້ Mid-Dovinian cladoxylopsid ໃນຕອນຕົ້ນທີ່ບໍ່ໄດ້ຮັບການຍອມຮັບໃນຫີນ Hangman Sandstone ຂອງ Somerset ແລະ Devon ໃນພາກຕາເວັນຕົກສຽງໃຕ້. ປະເທດອັງກິດ. The site contains free-standing fossil trees or fossil forest dating from 390 million years ago which makes it the oldest fossilised forest known on ແຜ່ນດິນໂລກ – about four million years older than the previous record holder fossil forest found in New York State. The study sheds light on the impact of the oldest forests.
ໄດ້ cladoxylopsid trees resembled palm trees but lacked leaves. Instead of solid wood, their trunks were thin and hollow in the centre and their branches were covered in hundreds of twig-like structures that dropped on the forest floor as the tree grew. The trees formed dense forests with very high abundance of plant debris on the floor. There was no growth on the floor as grass had not evolved yet but abundance of droppings by the densely packed trees had a big impact. The debris supported invertebrate life on the floor. The sediments on the floor influenced the flow of the rivers and resilience against floods. This was first time in the history of ແຜ່ນດິນໂລກ that tree-driven changes influenced course of rivers and non-marine landscapes of the ດາວ ປ່ຽນແປງຕະຫຼອດໄປ.
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ກະສານອ້າງອີງ:
- Davies N.S., McMahon W.J., and Berry C.M., 2024. ໂລກ earliest forest: fossilized trees and vegetation-induced sedimentary structures from the Middle Devonian (Eifelian) Hangman Sandstone Formation, Somerset and Devon, SW England. Journal of the Geological Society. 23 February 2024. DOI: https://doi.org/10.1144/jgs2023-204
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