A rapid Assessment of Post-fire Changes in Biophysical Variables, Carbon Stocks, and Soil Microbial Processes in the Tallest Angiosperm Forest

乔治·W·科赫，IOS-1010769，火灾后最高被子植物森林中生物物理变量、碳储量和土壤微生物过程变化的快速评估。该项目调查了2009年2月地球上最高的阔叶林--澳大利亚维多利亚的袋鼠溪分水岭--发生的火灾对生态的影响，该分水岭以桉树为主。白蜡树是生长最快的树木之一，其森林因其高固碳潜力而被公认，但桉树森林中普遍存在的火灾引发了对这种碳的持久性的质疑。调查人员自2005年以来一直在研究这片森林，并掌握了有关火灾前状况的大量信息，包括对单株树木质量的高度准确估计。这项后续研究评估了土壤和在火灾中死亡的树木的碳储量的变化，并对死亡树木的树冠进行采样，以测试有关木材解剖和化学特性随高度变化的基本观点。从烧毁和未烧毁的森林中收集的土壤和树木样本，以及火灾前研究的树木尺寸的测量，将被用于估计碳储量的变化。从枯树树冠内不同高度收集的木材样本将在实验室进行分析，以检验关于极高树木导水室尺寸优化设计的理论。分析木材样品的化学成分(碳的两个稳定同位素的相对丰度)将被用来了解长期综合水分胁迫的变化。这项研究将对树木高度和大小生长的制约因素以及火灾在森林碳循环中的作用产生新的理解，随着一些地区的火灾频率和严重程度随着气候变化而增加，这一问题变得越来越重要。这项研究将涉及美国学生(本科生和研究生)、博士后助理和教职员工，他们将与澳大利亚的技术助理和大学研究人员合作。

George W. Koch, IOS- 1010769, A rapid assessment of post-fire changes in biophysical variables, carbon stocks, and soil microbial processes in the tallest angiosperm forest. The project examines ecological impacts of the February 2009 fire in the tallest broad-leaf forest on Earth, the Wallaby Creek watershed in Victoria, Australia dominated by Eucalyptus regnans (?Mountain Ash?). Mountain Ash is among the fastest growing trees, and its forests are recognized for their high carbon sequestration potential, yet the prevalence of fires in eucalypt forests raises questions of the permanence of that carbon. The investigators have studied this forest since 2005 and have extensive information on pre-fire conditions, including highly accurate estimates of the mass of individual trees. This follow-up study assesses changes in carbon stocks of soils and trees killed in the fire and samples the crowns of dead trees to test fundamental ideas about height-related variation in wood anatomical and chemical properties. Samples of soils and trees collected from burned and unburned stands, and measurements of dimensions of trees studied prior to the fire, will be used to estimate changes in carbon stocks. Wood samples collected from different heights within the crowns of dead trees will be analyzed in the laboratory to test theories about the optimal design of the dimensions of the water-conducting cells in extremely tall trees. Analysis of the chemical composition (the relative abundance of two stable isotopes of carbon) of wood samples will be used to understand variation in long-term, integrated water stress. The study will produce new understanding of the constraints on tree height and size growth and of the role of fire in the forest carbon cycle, an issue of increasing importance as fire frequency and severity increases with climate change in some regions. The study will involve U.S. students (undergraduate and graduate), postdoctoral associates, and faculty who will collaborate with Australian technical assistants and university researchers.