The Carbon Balance of Semi-Arid Ecosystems: Why Southern Africa Carbon-Climate Dynamics are uniquely different

Abstract:

Previous studies by Poulter et al (2014) and Alhstrom et al (2015) have shown that the semi-arid ecosystems (e.g. Australia) can dramatically alter the regional and global net carbon sink/source status depending on sporadic precipitation. For example, the unprecedented huge carbon sink which occurred in 2011 was mainly due to the growth semi-arid vegetation over Australia; which was driven by increased precipitation.

Thus, we sought to uncover if this was the case with the semi-arid ecosystems in southern Africa. We used 10 models from the “Trends In Net Land-Atmosphere Carbon Exchange – Model Inter comparison Project (TRENDY-MIP)” to evaluate response of southern Africa semi-arid ecosystems to precipitation in the 20^th century. Our study revealed that the sensitivities and net carbon source/sink dynamics in these ecosystems are distinctly different from those elsewhere owing to opposite climate anomalies; i.e. the region receives sporadic precipitation drops, rather than spikes which is the case in other semi-arid regions.

The implications for this study is explored in an ecosystem services context for future trajectories of the region as the ability of the ecosystems to continually provide such services directly depends on the soaring population rise in the region.

Key words: Semi-arid ecosystem, Southern Africa, TRENDY-MIP, Carbon dynamics and climate change.