Weathering, Plants, and the Long-Term Carbon Cycle

对显生宙地球化学碳循环及其对大气CO2影响的建模（Berner, 1990;1991）揭示了更多地了解陆地植物如何影响化学风化的重要性。这包括植物对硅酸盐吸收二氧化碳速率的影响，以及有或没有植物的风化对二氧化碳变化的反馈反应。该项目将通过对夏威夷岛的实地研究来调查植物在风化中的作用。夏威夷为研究风化提供了一个独特的机会，因为这里有：(1)可以追溯到4000多年前的玄武岩；(2)在恒定的基岩岩性和恒定的小气候的小区域内，有各种各样的植物，从地衣和藻类到发育良好的雨林；(3)可以接触到目前正在同一地区研究植物生态学的生物学家的专业知识。我们计划测量风化皮和流上土壤的厚度、矿物学和化学成分，以比较在存在和不存在特定生物群的情况下风化的相对速率。这项工作的结果，结合未来计划研究的结果，即在不同二氧化碳水平下生长的特定植物对风化率的影响，将被用于我们的碳循环模型，以对维管植物在地质时期的兴起如何导致大气中二氧化碳的变化进行一些限制

Modeling of the geochemical carbon cycle and its effect on atmospheric CO2 over Phanerozoic time (Berner, 1990;1991) has revealed the importance of knowing more about how land plants affect chemical weathering. This includes the effect of plants on the rate of uptake of CO2 by silicate and the feedback response of weathering, with and without plants, to changes in CO2. This project will investigate the role of plants in weathering by a field study on the island of Hawaii. Hawaii offers a unique opportunity to study weathering because here there are: (1) dated basalts ranging back to more that 4000 years (2) a wide range of plant life, from lichens and algae to well developed rainforest, within small regions of constant bedrock lithology and constant microclimate and (3) access to the expertise of biologists who are presently studying plant ecology in the same area. We plan to measure the thickness and mineralogical and chemical composition of weathering rinds and soils on flows with an eye to comparing relative rates of weathering in the presence and absence of specific biota. Results of this work, when combined with results from planned future studies of the effects of specific plants grown at varying CO2 levels on weathering rate, will be employed on our carbon cycle model to place some limits on how atmospheric CO2 might have changed as a result of the rise of vascular plants over geologic time