Strong and Rapid Postfire Recovery of Vegetation Productivity in Australia

Abstract

Fires disrupt ecosystems, release carbon, and reduce carbon uptake, which increases atmospheric CO2 concentration, warms the atmosphere, and fosters more frequent and intense fires. Quantifying postfire recovery is crucial for understanding the adaptability and resilience of ecosystems to fire disturbances. Observations from satellite-derived active fire (~1-km) and Gross Primary Productivity (GPP) products reveal that Australia experiences extensive fires annually, reducing vegetation productivity. Here we analyze the post-fire GPP recovery trajectories of 1.7 × 106 fire-affected pixels (or 1.5 × 106 km2) in Australia between 2011 and 2019, of which 1.3 × 106 pixels (1.2 × 106 km2) experienced a single fire (single-fire pixels), and 0.4 × 106 pixels (0.3 × 106 km2) experienced two or more fires (multiple-fire pixels). We found that Australia's postfire GPP recovery was strong and rapid. 88% of single-fire pixels recovered to 135% of the prefire level in an average of 2.3 years, whereas 86% of multiple-fire pixels recovered to 115% of the prefire level in an average of 1.2 years. NonForest ecosystems (e.g., grasslands, shrublands, and savannas) exhibited a higher postfire recovery magnitude (138% for single-fire pixels and 115% for multiple-fire pixels) compared to Forest (110% for single-fire pixels and 108% for multiple-fire pixels). This rapid and robust postfire GPP recovery is significantly influenced by postfire precipitation, fire (i.e., fire frequency, intensity) and fire severity (damage, impacts; a metric of resistance of terrestrial ecosystems to fire). Specifically, higher fire severity and higher postfire precipitation have a positive impact on postfire recovery, whereas increased fire frequency has a negative impact. Furthermore, fire dynamics have a smaller role in the long-term interannual continental GPP changes than climate or land-use changes, as strong and rapid GPP recovery offsets the short-term fire-induced GPP losses.