Contrary to earlier estimates, it is not only young forests that actively sequester carbon dioxide from the atmosphere.
Researchers from the Forest Institute of the Krasnoyarsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences studied the "carbon budget" of the old northern forests of Eurasia and came to the conclusion that their role in carbon dioxide binding had been seriously underestimated earlier. The corresponding article was published in Biology Bulletin.
For a long time, it was believed that only young forests bind atmospheric carbon dioxide most effectively. Plants build their biomass from CO2 and water, so it is logical that during the period of rapid forest growth, it intensively binds carbon dioxide. It was also believed that as the forest ages, it becomes "carbon neutral": all the CO2 that it binds returns back to the atmosphere, since heterotrophic organisms (primarily fungi) decompose wood residues and at the same time release CO2 (the carbon in which from dead old trees) as a product of their vital activity. This picture was indeed confirmed by observations of old forests in southern countries.
The authors of the new work studied in detail the fate of plant residues in different ecosystems - from larch forests on the border of taiga and tundra to spruce forests of the southern taiga. Scientists used the data of long-term observations of different forest areas of the Krasnoyarsk Territory. It turned out that the situation with the carbon dioxide cycle is not at all as unambiguous as previously assumed.
In taiga conditions, heterotrophs do not have time to normally decompose deciduous litter and wood of dead trees. This is hindered by both low temperatures, which impede the rapid reproduction of fungi, and a number of other factors. Plant residues under the weight of the next layers of litter fall too quickly into the permafrost, where they accumulate in large quantities. In typical taiga forests, no less biomass gets into such undecomposed plant residues than is contained in living trees, and in larch forests (on the border with the tundra) the mass of plant residues not processed by heterotrophs can be twice as large as the standing (still living) trees themselves.
The work shows that the role of northern forests in binding carbon dioxide is much higher than it was thought, and it is inappropriate to transfer jungle norms to them in this regard. All this means that taiga acts as an effective brake on global warming and its reduction can upset the balance and accelerate warming. In addition, it is important to take into account the influence of different forests on global warming in the framework of agreements such as the former Kyoto or the current Paris one, in order to take into account the specific contribution of this or that country to the fight against global warming. The assessment of this contribution also determines the restrictions imposed on the state on the regulation of CO2 emissions by its industry.