Soil life plays an important role in climate change forecasts. They store the majority of Earth’s terrestrial carbon, and so play a crucial role in the direction and magnitude of future climate changes. If more carbon is released than taken up by soils, then climate change will be accelerated and temperatures will rise further, creating a positive feedback. The main way in which soils release carbon to the atmosphere is through soil respiration, which is the sum of respiration rates for all of the organisms that live in the soil (plant roots, microbes and animals). Yet, because soils are extremely complex systems, quantifying the contribution of different organisms to soil respiration rates is hard to perform experimentally.
In a recently published study in Nature Ecology & Evolution, SSP fellow Alice Johnston set about doing this. The authors found that soils in the northern regions of Europe, America and Asia contain more microbes and smaller animals than those in southern regions and the tropics, and these are more sensitive to warmer temperatures. These organisms are therefore likely to release carbon dioxide at a faster rate than those in warmer parts of the world. What is particularly worrying is that these high latitude soils store a huge amount of carbon and so an increase in soil respiration here could dramatically accelerate future climate change. However, to accurately predict future climate changes we need to better understand how soil communities will change in the future.
Figure: More accurate soil respiration predictions when soil communities and their different metabolic rates are included (a) or excluded (b), compared to the linear regression approach often used in climate models (c).