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

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

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.