Carbon Dioxide and Water Cycling in Tropical Forests

9315697斯滕贝格将在两个热带雨林（季节性森林和非季节性森林）的不同高度，在白天和晚上测定水蒸气和环境二氧化碳的同位素组成和浓度。 这些气体的同位素值将与潜在来源进行比较：土壤呼吸和大气中的二氧化碳;土壤蒸发，蒸腾和大气中的水蒸气。 这些测量将回答以下关于亚马逊雨林中二氧化碳和水循环的问题：亚马逊森林中的热带树木需要多少土壤剖面提供水分？ 土壤蒸发、蒸腾和大气湿度对森林环境湿度的贡献是什么？ 通过光合作用重新固定的呼吸的二氧化碳量是多少？ 在光合作用过程中，环境中二氧化碳的氧同位素组成如何受到与叶水平衡的影响？ 这些问题的答案将推进我们对世界上最大的连续森林-亚马逊-中二氧化碳和水循环动态的了解。

9315697 Sternberg Isotopic composition and concentration of water vapor and ambient carbon dioxide will be determined at various heights in two tropical rain forests, (a seasonal and an aseasonal forest), during the day and night. Isotopic values of these gases will be compared with that of potential sources: soil respiration, and atmospheric for carbon dioxide; and soil evaporation, transpiration, and atmospheric for water vapor. These measurements will answer the following questions about carbon dioxide and water cycling in the Amazonian rain forest: What levels of the soil profile provide water for tropical trees in the Amazonian forest? What is the contribution of soil evaporation, transpiration, and atmospheric moisture to the ambient humidity in the forest? What is the amount of respired carbon dioxide refixed by photosynthesis? How is the oxygen isotopic composition of ambient carbon dioxide influenced by equilibration with leaf water during photosynthesis? The answers to these questions will advance our knowledge on the dynamics of carbon dioxide and water cycling in the largest stand of continuous forest in the world; the Amazon.