DISSERTATION RESEARCH: Drivers of Carbon Uptake in Tropical Forests: Implications for the Future of the Global Carbon Sink

论文研究：热带森林碳吸收的驱动因素：对全球碳汇未来的影响

• 批准号: 1401664
• 负责人: James Kellner
• 金额: $ 2.11万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1401664&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Drivers; Carbon; Uptake

The world's oceans and forests annually absorb half of all carbon dioxide (CO2) emissions from human activities. Recent studies indicate that intact forests in the tropics may account for as much as one-third of the global uptake of carbon emissions by forests. Carbon uptake in these forests is widely attributed to increased plant growth as a result of rising atmospheric CO2 concentrations. CO2 is the raw material from which plants build leaves, roots, and wood, and experiments in greenhouses and intact forests demonstrate that plant growth often increases under higher CO2 levels, an effect known as CO2 fertilization. Although climate models project that forests will continue to absorb carbon over this century, the magnitude of this carbon uptake and the degree to which it changes over time will depend on the availability of other resources required by plants. Forests on higher fertility soils with sufficient water and sunlight are likely to experience larger and longer-lasting increases in growth than forests on lower fertility soils which lack sufficient levels of these resources. The objective of this research is to estimate the degree to which resource availability constrains forest growth in the tropics at the scale of entire regions, such as the Amazon Basin. Using newly developed computer algorithms that produce three-dimensional (3D) models from two-dimensional images, it is possible to derive 3D models of tropical forests from high-resolution satellite imagery. Carbon uptake by tropical forests can be estimated by calculating the difference in forest models between two time periods. This work will analyze variation in carbon uptake with factors, such as rainfall, temperature, elevation, and soil age, in order to estimate the degree to which resource availability limits forest growth throughout the tropics. Quantitative information about the severity of resource limitation is necessary to constrain estimates of how much carbon forests are likely to absorb over this century, which is essential to improving climate projections. Furthermore, this work has direct implications for the optimal design of emissions reduction policy. The economic cost of achieving a given atmospheric CO2 concentration depends on how much carbon forests can be expected to absorb. The more resource limitation constrains carbon uptake in forests, the steeper emissions reductions must be to achieve a given atmospheric CO2 concentration.

全世界的海洋和森林每年吸收人类活动排放的二氧化碳的一半。最近的研究表明，热带地区完整的森林可能占全球森林吸收的碳排放量的三分之一。这些森林的碳吸收被广泛归因于大气CO2浓度上升导致的植物生长增加。CO2是植物生长叶子、根和木材的原材料，温室和完整森林中的实验表明，植物生长通常在较高的CO2水平下增加，这种效应称为CO2施肥。虽然气候模型预测，森林将在本世纪继续吸收碳，但这种碳吸收的规模及其随时间变化的程度将取决于植物所需其他资源的可用性。土壤肥力较高、水和阳光充足的森林，其生长速度可能比土壤肥力较低、缺乏足够水和阳光的森林更快、更持久。这项研究的目的是估计资源的可用性在多大程度上限制森林生长在热带地区的整个区域的规模，如亚马逊盆地。利用新开发的从二维图像生成三维模型的计算机算法，有可能从高分辨率卫星图像生成热带森林的三维模型。热带森林的碳吸收可以通过计算两个时期之间森林模型的差异来估计。这项工作将分析碳吸收与降雨、温度、海拔和土壤年龄等因素的变化，以估计资源可用性限制整个热带地区森林生长的程度。关于资源限制严重程度的定量信息是必要的，以限制对本世纪森林可能吸收多少碳的估计，这对改善气候预测至关重要。此外，这项工作有直接的影响，优化设计的减排政策。达到一定的大气CO2浓度的经济成本取决于森林预计能吸收多少碳。资源限制对森林碳吸收的限制越大，就必须更大幅度地减少排放，以达到一定的大气CO2浓度。