It has long been recognized that the advent of vascular plants in the Paleozoic must have changed silicate weathering and fundamentally altered the long-term carbon cycle. Carbon cycle models are frequently employed to quantify the effect of this state change in the Earth system. These models have suggested that plants likely played a key role in modulating atmospheric CO2 in the past, with the largest plant-induced changes to the system in the late Paleozoic. These studies have, for the most part, focused on the effects of plants on weathering via their impacts on the soil environment. Yet, plants also modify the hydrological cycle, which may also have had implications for global weathering. Here, we evaluate the consequences of plant evolutionary innovation that have not been previously incorporated into carbon cycle models by coupling a one-dimensional vapor transport model to a reactive transport model of silicate weathering. Using this cascade of models, we investigate: 1) how evolutionary shifts in plant transpiration may have enhanced silicate weathering through increased downwind transport of water vapor to continental interiors; 2) the importance of deeply-rooted plants and their associated microbial communities in increasing soil CO2 and weathering zone length scales; and, 3) the coupled effect of these two processes on weathering rates. The hydrologic balance for our modeling approach is framed by energy/supply constraints (encapsulated through Budyko relationships) calibrated for minimally vegetated-, vascular plant forested-, and angiosperm-worlds. Using constraints for atmospheric vapor-transport over continents and terrestrial weathering fluxes, we find that the emergence of widespread transpiration and associated inland vapor recycling associated with the advent of deep-rooted vascular plants over the later Devonian increases weathering solute concentrations by a factor of 1.64 to 2.39 for a fixed atmospheric CO2. The later domination of ecosystems by angiosperms in the late Cretaceous and Cenozoic, and the subsequent increase in transpiration fluxes, increased weathering solute concentrations by 7 to 55 percent leading to a cumulative total increase in weathering solute concentrations by a factor of 1.70 to 2.55. Partitioning of the vapor recycling effects and feedbacks on the weathering thermodynamics indicates that 55 percent of the increases in weathering concentrations are due to the thermodynamic effects of soil CO2 with the remaining 45 percent attributable to hydrologic effects. Our estimates of the relative changes in weathering solute concentrations caused by land plant evolution are of a similar magnitude to relative flux scaling relationships implemented in existing carbon cycle models such as GEOCARBSULF (Berner, 2006), COPSE (Bergman and others, 2004), and GEOCLIM (Le Hir and others, 2011). As Phanerozoic plant evolution resulted in a more efficient generation of weathering solutes, a weaker dependence of silicate weathering on physical forcing factors such as temperature, pH of rainwater, tectonics, and prevailing lithology, must have resulted. Consequently, we postulate that terrestrial plant evolution likely contributed to a more stable climate system over the Phanerozoic.

中文翻译：

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模拟陆地植物进化对硅酸盐风化的影响

人们早就认识到，古生代维管植物的出现一定改变了硅酸盐风化并从根本上改变了长期的碳循环。碳循环模型经常被用来量化地球系统中这种状态变化的影响。这些模型表明，过去植物可能在调节大气 CO2 中发挥了关键作用，在晚古生代植物引起的系统变化最大。这些研究大部分都集中在植物对土壤环境的影响对风化的影响上。然而，植物也会改变水文循环，这也可能对全球风化产生影响。这里，我们通过将一维蒸汽传输模型与硅酸盐风化的反应传输模型耦合来评估之前未纳入碳循环模型的植物进化创新的后果。使用这一系列模型，我们研究了：1）植物蒸腾作用的进化变化如何通过增加水蒸气向大陆内部的顺风输送来增强硅酸盐风化；2) 深根植物及其相关微生物群落在增加土壤二氧化碳和风化带长度尺度方面的重要性；3) 这两个过程对风化速率的耦合影响。我们建模方法的水文平衡是由能源/供应约束（通过 Budyko 关系封装）为最小植被、维管植物森林、和被子植物世界。使用大陆上的大气蒸汽传输和陆地风化通量的约束，我们发现广泛的蒸腾作用的出现和相关的内陆蒸汽循环与晚泥盆纪深根维管植物的出现相关，使风化溶质浓度增加了 1.64 倍对于固定的大气 CO2 为 2.39。晚白垩世和新生代被子植物对生态系统的支配，以及随后蒸腾通量的增加，使风化溶质浓度增加了 7% 到 55%，导致风化溶质浓度累计增加了 1.70 到 2.55 倍。蒸汽循环效应和风化热力学反馈的划分表明，风化浓度增加的 55% 是由于土壤 CO2 的热力学效应，其余 45% 可归因于水文效应。我们对陆地植物进化引起的风化溶质浓度的相对变化的估计与现有碳循环模型中实施的相对通量比例关系相似，例如 GEOCARBSULF（伯纳，2006 年）、COPSE（伯格曼等人，2004 年）和GEOCLIM（Le Hir 等人，2011 年）。由于显生宙植物进化导致更有效的风化溶质生成，硅酸盐风化对物理强迫因素（如温度、雨水 pH 值、构造和主要岩性）的依赖性较弱，一定是结果。因此，我们假设陆生植物进化可能有助于显生宙上一个更稳定的气候系统。