- Title:
-
Alpine Soil as a Methane Sink: Controlling factors and fire effects
- Date:
- September 2009
- Organisations
- AFAC 2009 Conference
- Authors:
- Department of Forest and Ecosystem Science, The University of Melbourne, Creswick, VIC, Australia
- Bushfire CRC, Melbourne, VIC, Australia
-
Location:
-
Australia,
Australia
Overview
Fire drastically and rapidly changes forest ecosystems by removing vegetation, exposing soil and depositing ash. The visible effect of fire is well known but much less is understood about the effects on atmospheric greenhouse gases. Methane (CH4) is an important greenhouse gas, trapping more heat than CO2 on a unit mass basis. Aerobic soils, such as those found in forests are important sinks of CH4 consuming 15-45 Tg yr-1 of atmospheric CH4 globally (3-10% of emissions). Methanotrophic bacteria responsible for this sink are greatly affected by soil disturbances such as fire . Sites in the Bogong High Plains, Victoria are currently being studied for the effect of abiotic properties of soil on CH4 consumption in alpine forest ecosystems. Sites are located in either Snow gum (Eucalyptus pauciflora) woodlands or Alpine ash (E. delegatensis) forests and encompass a range of fire histories. Soils from all sites have been shown to be sinks of CH4 , with consumption rates ranging from 28 to 105 (mean 59) µg CH4 m-2 h-1 in Alpine ash sites and 25 to 133 (mean 73) µg CH4 m-2 h-1 in Snowgum sites. Field consumption rates of CH4 were not obviously related to measured soil properties, including elevated ammonium concentration after fire which is thought to inhibit CH4 concentration. Laboratory studies have been used to disentangle the effects of fire on methane consumption and determine the soil properties that play an important role in controlling consumption rates. The effects of individual key abiotic properties such as CH4 diffusion, soil moisture, temperature, bulk density, inorganic nitrogen and pH have been investigated. This presentation will focus on soil properties most sensitive to fire with the aim of predicting how fire will change our alpine soil methane sink.
