Rising atmospheric CO2 levels globally affect the photosynthesis of peat moss – Interested in that?

Peer-reviewed publications

Peer-reviewed publications


Jürgen Schleucher

Scientists at Umeå University, Sweden and the Swedish University of Agricultural Sciences have developed ways to decipher the effect of CO2 increases over the past 100 years on the metabolic flows of species Important vegetation in peat, mossy lands. Analyzes of cellulose in peat cores collected by collaborative scientists working on five continents indicate that the increase in CO2 during moss photosynthesis is strongly dependent on groundwater levels, which can can change the species composition of peat moss communities.

As human CO2 emissions continue to occur, it becomes increasingly important to capture CO2 to mitigate the associated climate change. Peatlands are the largest global store of soil carbon, but the impact of climate change on peatlands is unknown. Over the course of the 20th century, global atmospheric CO2 concentrations have increased by almost 50% and further increases are inevitable according to the Intergovernmental Panel on Climate Change, IPCC, with dire consequences. for humanity. So far, CO2 uptake by the terrestrial biosphere has reduced CO2 increases and prevented further severe effects.

Although peatlands cover only 3% of the global land surface, they store a third of all global soil carbon. Therefore, CO2 absorption by peat moss is important, but little is known about how their physiology is affected as CO2 levels rise. To find out if peatlands will continue to store carbon and mitigate future climate change, scientists studied the response of peat moss to an increase in atmospheric CO2. .

For the study, collaborating researchers from five continents collected peat cores from ten locations worldwide. In a new study using nuclear magnetic resonance imaging, the distribution of stable hydrogen isotopes in the cellulose of modern peat moss and many centuries later has been compared. This allowed us to reconstruct the changes in photosynthetic efficiency over the 20th century, by estimating the impact of photorespiration, a side effect of photosynthesis.

“The photorespiration process is very important for the carbon balance of plants because it reduces the efficiency of photosynthesis by up to 35 per cent at a time,” said Jürgen Schleucher, Professor in the Department of Biochemistry and Medical Biophysics. Umeå University, Sweden.

The analysis shows that the increase in CO2 over the past 100 years has reduced optical dispersion, which presumably has fueled carbon storage in the peatlands to date and alleviated climate change. . However, increasing atmospheric CO2 only reduced photomolecular phenomena in peatlands when water levels were moderate, but not when conditions were too wet or too dry. Unlike higher plants, mosses cannot transport water, so the groundwater table controls their humidity, which affects their photosynthetic efficiency. Therefore, models based on physiological responses of higher plants cannot be applied.

The impact of groundwater-dependent CO2 can have major consequences for peatland species composition, as only mosses that grow at intermediate distances from the water table will benefit. from higher atmospheric CO2 concentrations. Furthermore, changes in the water balance of peatlands can strongly affect their future carbon balance because conditions that are too wet or too dry reduce the ability of peat moss to remove carbon. mud.

Although peatlands have so far mitigated climate change caused by CO2, these changes have had devastating effects. If human CO2 emissions are not drastically reduced, atmospheric CO2 concentrations will continue to rise by hundreds of ppm by 2100, and average global temperatures will rise several degrees above pre-industrial levels. C. It is not clear how peatlands will be affected by this.

“To get a clearer picture of the importance of photochemistry for peat moss and peat carbon accumulation, the next step is to transfer our data to modified photosynthesis models. to estimate global peatland carbon. Future CO2 concentrations, rising temperatures, changes in precipitation and groundwater levels will need to be considered to predict the fate of peatlands under changing climates, says Jürgen Schleucher.


Scientific reports


10.1038 / s41598-021-02953-1


Global CO2 fertilization of Sphagnum peat moss through inhibition of light scattering in the 20th century


December 31, 2021


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