Nonlocal Carbon-Water Interactions in Australia: Going with the Flow

Abstract:

Identifying the mechanisms underlying carbon-water interactions is integral to understanding the spatiotemporal patterns of biogeochemical cycling. In water-limited regions, the available soil water is the dominant driver of carbon cycling^a. The lateral flow of large volumes of water through rivers, streams and floodplains can support ecosystems thousands of kilometers away from the location of the source precipitation. This mechanism of biogeochemical cycling that is commonly overlooked is also absent from global land surface models. This study focuses on one of the largest unregulated catchments in the world, the Kati Thanda­–Lake Eyre Basin, which covers approximately one sixth of the Australian continent. Using a combination of satellite remote sensing measurements, in-situ streamflow measurements, land surface model simulations, and hydro-morphology data, we investigate the carbon-water dynamics of this semi-arid region over a multi-year timescale. The episodic nature of precipitation in this region drives large flows of water downstream. This supports hot spots of vegetation growth that are more persistent than regions without significant lateral water transport. We further quantify the contribution of the numerous streams, floodplains and non-stream regions to large-scale variability in the Australian carbon cycle. This study highlights the newly discovered and significant role of lateral transport of water in terrestrial carbon cycle studies.

^a Jung, M. et al. doi.org/10.1038/nature20780