Disturbance impacts on carbon exchange and water loss in a managed native Eucalyptus forest

Forests have an important role in the global carbon cycle. Of the total emissions from human activities during the period 2003-2012, about 45% accumulated in the atmosphere, 27% in the ocean and 27% on land (GCP, 2013). Forest carbon sinks are vulnerable to disturbances, both human-induced and natural, that can lead to significant net transfers of carbon from the land to the atmosphere. Disturbances shape forest systems by influencing their composition, structure, and functional processes.

Disturbances in Bago - Maragle State Forest include logging, drought and pathogens/insects. This paper reviews impacts of drought conditions that led to an insect outbreak. Data from the flux tower 'Tumbarumba' confirm that this disturbance turned the forest from being a strong sink of carbon to a source. During a 9 month period, the forest lost carbon to the atmosphere. Ground based field measurements and satellite imagery show that species were affected differently but overall a reduced biomass increment and increased mortality were observed.

We further analyse impacts of (selective) logging on the exchanges of carbon and water. Landsat images provide a unique data source for reconstructing forest disturbance history at a fine spatial resolution. We have analysed Landsat7 ETM+ cloud free imagery to determine the extent and duration of disturbance in Bago - Maragle State Forest both during a drought period and due to logging practices. We use an integrated flux and remote sensing data - modeling approach to quantify the impact of disturbance.