The influence of snow on net ecosystem exchange over an alpine meadow in the Australian Alps

Abstract. Accurate modelling of climate change is underpinned by a robust understanding of the sources and sinks of carbon to the atmosphere. Currently, net ecosystem exchange over the distinct alpine meadow ecosystems of the Australian Alps has not been quantified, with limited understanding of the influence of environmental drivers such as snow, despite their sensitivity to climate change. We established an eddy covariance tower on an alpine meadow situated in the headwaters of the Pipers Creek catchment in the Australian Alps, collecting continuous half-hourly CO₂ fluxes from the 10^th June 2016 to the 19^th November 2019. The meadow functioned as a net carbon sink under snow-free conditions, transitioning to a net carbon source under snow-cover. This distinction was predominantly driven by the attenuation of photosynthetically active radiation and insulation of soil temperatures facilitated by the snowpack, preferentially inhibiting gross primary productivity. The site is found to be a stronger net carbon sink compared with other alpine meadow systems, globally, primarily due to a comparatively shorter snow-cover period. With the spatial and temporal extent of snowpacks in the Australian Alps anticipated to decrease under future climate scenarios, the sink strength of these alpine meadows is expected to increase.