Fire, Atmospheric pCO2, and Climate as Alternative Primary Controls of C4-Grass Abundance: The Late-Quaternary Perspective

火灾、大气 pCO2 和气候作为 C4 草丰度的替代主要控制因素：晚第四纪视角

• 批准号: 0816610
• 负责人: Feng Sheng Hu
• 金额: $ 42.61万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-15 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0816610&HistoricalAwards=false
• 关键词: Fire; Atmospheric; pCO2; Climate; Alternative

Grass-dominated ecosystems cover about one-third of Earth's land surface, influence global biogeochemical processes (e.g. water, carbon, and nutrient cycling), and serve as major food sources for humans and herbivores. These ecosystems are among the most sensitive to future changes in climate and atmospheric chemistry. This sensitivity can be partially attributed to the differential responses of two major functional groups, C3 and C4 plants. C4 plants gain competitive advantages under certain environmental conditions (e.g. fire, heat, drought, and low pCO2). C3 and C4 plants in turn have distinct influences on major biogeochemical processes; for example, the role of C4 plants in global net primary production is disproportionately large. Despite these well-known differences, it remains controversial what environmental factors directly control the relative abundances of C3 and C4 plants. Paleoecological studies can help decipher the responses of C3 and C4 plants to a wide range of environmental conditions, thereby offering information for anticipating future changes. This project will evaluate the effects of fire, climate, and atmospheric CO2 concentration on the variation of C4-grass abundance over the past 25,000 years in East Africa and Australia. The researchers will analyze sediment cores for a suite of ecological proxy indicators and develop a novel technique to estimate the abundance of C4 plants in geological records. This project provides an excellent context for educating the general public on climate change and grassland ecology. The researchers will organize summer courses targeting middle and high school teachers as well as land managers.

占地为主的生态系统覆盖了地球地面的三分之一，影响了全球生物地球化学过程（例如水，碳和养分循环），并作为人类和草食动物的主要食物来源。 这些生态系统对气候和大气化学的未来变化最敏感。 这种敏感性可以部分归因于两个主要官能团C3和C4植物的差异反应。 在某些环境条件下（例如火灾，热量，干旱和低PCO2），C4植物获得了竞争优势。 C3和C4植物反过来对主要的生物地球化学过程产生了不同的影响。例如，C4植物在全球净初级生产中的作用不成比例。 尽管存在这些众所周知的差异，但仍然有争议的是哪些环境因素直接控制C3和C4植物的相对丰度。 古生态学研究可以帮助破译C3和C4植物对各种环境条件的反应，从而提供预测未来变化的信息。 该项目将评估火灾，气候和大气二氧化碳浓度对过去25，000年在东非和澳大利亚的C4-草丰度变化的影响。 研究人员将分析一系列生态代理指标的沉积物核心，并开发一种新型技术来估计地质记录中C4植物的丰度。该项目为对普通公众的气候变化和草地生态学提供了良好的背景。研究人员将组织针对中学和高中教师以及土地经理的夏季课程。