A plant component as an oxygen controller
A plant component, lignin, has been of great importance in atmospheric oxygen control over the last 200 million years.
According to Jennifer Robinson of the University of Pennsylvania, lignin influences the composition of the atmosphere a lot, since it is very difficult to degrade it. Degradation is a process similar to burning that requires oxygen. Formerly, when lignin was very abundant, degradation was very slow in nature. Therefore, oxygen accumulated in the atmosphere.
In order to make this claim, Robinson has analyzed the compositions of coal and its accumulated isotopes over the last 450 million years. According to their estimates 380 million years ago the oxygen level was 15%, but in the Charcoal, 300 million years ago, the oxygen level was 35%. At this time oxygen levels are about 20%.
In the charcoal the trees had more trunks than the wood and in the bark of the trunk is usually lignin. As previously mentioned, lignin hinders plant degradation, so less oxygen was consumed than at other times.
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