MODELING THE EVOLUTIONARY RISE OF ECTOMYCORRHIZA ON SUB-SURFACE WEATHERING ENVIRONMENTS AND THE GEOCHEMICAL CARBON CYCLE
MODELING THE EVOLUTIONARY RISE OF ECTOMYCORRHIZA ON SUB-SURFACE WEATHERING ENVIRONMENTS AND THE GEOCHEMICAL CARBON CYCLE
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DOI：
10.2475/05.2011.01
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发表时间：
2011-05-01
影响因子：
2.9
通讯作者：
Beerling, David J.
中科院分区：
文献类型：
--
作者：
Taylor, Lyla;Banwart, Steve;Beerling, David J.
在过去的二十年里，被子植物在白垩纪和古近纪的传播被认为增强了Ca和Mg的硅酸盐风化通量到海洋，从而降低了大气中的CO2，并最终将其封存在海洋碳酸盐沉积物中。然而，在白垩纪被子植物树木的崛起是一致的外生菌根真菌协会的被子植物和裸子植物的树木，越来越多地取代了树木与祖先的丛枝菌根协会的演变。这代表了植物进化史上发生的最深刻的根功能变化，对风化和土壤地球化学具有深远的影响，因为细根被真菌鞘包裹。外生菌根真菌提供了与土壤的主要营养和吸水界面，以及有机酸和质子在单个矿物颗粒尺度上积极分泌的途径。在这里，我们测试的假设，外生菌根树木的崛起是一个主要的贡献者大气中的CO2在过去的120马通过增强硅酸盐风化下降。我们开发了一个基于过程的土壤化学模型，将植物与祖先丛枝菌根的影响，最近演变的外生菌根对土壤化学通过其对生物质子循环的影响，并将其整合到一个领先的长期碳循环模型（GEOCARBSULF）。我们的机制，基于过程的建模表明，外生菌根树的崛起可以解释以前的经验归因于被子植物的传播CO2下降。因此，我们认为，外生菌根的进化崛起通过增强化学风化和将大气二氧化碳吸收到海洋碳酸盐中，代表了长期碳循环的重要驱动力。
For the past two decades, the spread of angiosperm plants in the Cretaceous and Paleogene has been thought to have enhanced silicate weathering fluxes of Ca and Mg to the oceans, thereby drawing down atmospheric CO2 and ultimately sequestering it in marine carbonate sediments. However, the rise of angiosperm trees in the Cretaceous was coincident with the evolution of ectomycorrhizal fungal associations in angiosperm and gymnosperm trees that have increasingly supplanted trees with the ancestral arbuscular-mycorrhizal associations. This represents the most profound alteration in root functioning to occur in plant evolutionary history, with far-reaching implications for weathering and soil biogeochemistry because the fine roots are enveloped with a fungal sheath. Ectomycorrhizal fungi provide the main nutrient and water-absorbing interface with soil, and the pathway through which organic acids and protons are actively secreted at the scale of individual mineral grains. Here, we test the hypothesis that the rise of ectomycorrhizal trees was a major contributor to the drawdown of atmospheric CO2 over the past 120 Ma through enhanced silicate weathering. We developed a process-based soil chemistry model incorporating the effects of plants with ancestral arbuscular mycorrhizas, and more recently evolved ectomycorrhizas on soil chemistry via its effects on the biological proton cycle, and integrated it into a leading model of the long-term carbon cycle (GEOCARBSULF). Our mechanistic, process-based modeling reveals that the rise of ectomycorrhizal trees can explain the CO2 drawdown previously attributed empirically to the spread of angiosperms. We suggest, therefore, that the evolutionary rise of ectomycorrhizas represents an important driving force of the long-term carbon cycle by enhancing chemical weathering and draw-down of atmospheric CO2 into marine carbonates.