Constraining the role of early land plants in Palaeozoic weathering and global cooling.
Constraining the role of early land plants in Palaeozoic weathering and global cooling.
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DOI：
10.1098/rspb.2015.1115
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发表时间：
2015-08-22
期刊：
影响因子：
--
通讯作者：
Beerling DJ
中科院分区：
文献类型：
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作者：
Quirk J;Leake JR;Johnson DA;Taylor LL;Saccone L;Beerling DJ
超过 400 Ma 的早期陆地植物对陆地环境的殖民如何影响岩石风化、碳和磷的生物地球化学循环以及古生代的气候尚不清楚。在这里，我们通过实验证明，地草（早期陆地植物的现存谱系）与丛枝菌根（AM）真菌（如 410 Ma 早期陆地植物化石中的真菌）的矿物风化作用相比，与无植物对照相比，玄武岩颗粒中的钙风化作用增强了三到七倍。与无植物对照相比，菌根地钱的磷酸盐风化作用放大了 9-13 倍，而缺乏真菌共生体的地钱则放大了 5 至 7 倍。页硅酸盐矿物的侵蚀和挖沟随着 AM 真菌网络大小和大气 CO2 浓度的增加而增加。地草假根和菌丝体（0.1 m）或树根和菌丝体（0.75 m）深度的颗粒尺度风化速率的整合表明，具有浅锚固系统的早期陆地植物在增强总风化通量方面的效果可能比后来进化的树木至少低10倍。这项工作挑战了早期陆地植物显着增强了钙和磷的总风化和从陆地到海洋的通量的观点，这些通量被认为是奥陶纪短暂的剧烈大气二氧化碳封存和冰川作用的触发因素。
How the colonization of terrestrial environments by early land plants over 400 Ma influenced rock weathering, the biogeochemical cycling of carbon and phosphorus, and climate in the Palaeozoic is uncertain. Here we show experimentally that mineral weathering by liverworts—an extant lineage of early land plants—partnering arbuscular mycorrhizal (AM) fungi, like those in 410 Ma-old early land plant fossils, amplified calcium weathering from basalt grains threefold to sevenfold, relative to plant-free controls. Phosphate weathering by mycorrhizal liverworts was amplified 9–13-fold over plant-free controls, compared with fivefold to sevenfold amplification by liverworts lacking fungal symbionts. Etching and trenching of phyllosilicate minerals increased with AM fungal network size and atmospheric CO2 concentration. Integration of grain-scale weathering rates over the depths of liverwort rhizoids and mycelia (0.1 m), or tree roots and mycelia (0.75 m), indicate early land plants with shallow anchorage systems were probably at least 10-fold less effective at enhancing the total weathering flux than later-evolving trees. This work challenges the suggestion that early land plants significantly enhanced total weathering and land-to-ocean fluxes of calcium and phosphorus, which have been proposed as a trigger for transient dramatic atmospheric CO2 sequestration and glaciations in the Ordovician.