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Federal Research Center 
"Krasnoyarsk Science Center of the Siberian
Branch of the Russian Academy of Sciences"

 Федеральный исследовательский центр «Красноярский научный центр Сибирского отделения Российской академии наук»

Federal Research Center 
"Krasnoyarsk Science Center of the Siberian
Branch of the Russian Academy of Sciences"

The accelerated tree growth will not save the planet from global warming

23 May 2019 г.

Ускоренный рост деревьев не спасет планету от глобального потепления
An international team of researchers with the participation of scientists fr om the Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences and Siberian Federal University have found out that the life expectancy of trees is related to their growth rate. This means that an increase in the rate of radial growth of trees caused by global warming will not enhance their ability to store carbon dioxide. The research results are published in the journal Nature Communications.

Over the past hundred years, the average air temperature on our planet has increased by almost a degree Celsius. Scientists believe that the main cause of global warming is an increase in the concentration of greenhouse gases in the atmosphere, in particular, carbon dioxide. Carbon dioxide and other compounds create the greenhouse effect - they transmit sunlight to the Earth and prevent radiation from the heated ground surface from coming back into space.

In order to estimate how climate will change, it is important to understand the fate of carbon dioxide in the atmosphere. One of the important sinks of this greenhouse gas is wood. A large amount of carbon is stored in woody biomass. According to one of the assumptions, an increase in temperature and concentration of carbon dioxide in the atmosphere can lead to the increased growth of boreal forests, and, consequently, to their increased ability to retain carbon. However, until recently, scientists did not know exactly how realistic such a scenario is.

A team of scientists from several European countries evaluated the ability of trees to store more carbon in the case of the increased forest growth. It turned out that, at least, for conifers in forest ecosystems, wh ere the tree growth depends on the air temperature, the rule “the faster a tree grows–the faster it dies” holds. This means that even if the increase in temperature and concentration of carbon dioxide in the atmosphere enhances the growth of forests, trees will not be able to store more carbon and, consequently, to impede global warming.

For the analysis, scientists used the information encoded in tree rings from the highlands of the Altai and Spanish Pyrenees. The researchers had at their disposal data on the width of the growth rings of almost 800 living and a little more than 1000 dead mountain pines and Siberian larches, which grew in these areas virtually untouched by humans over the past two thousand years.

Scientists have found that conifers reach their maximum age, predominantly if they grow slowly at the beginning of life. For example, some fast-growing larch trees in Altai do not live longer than 100–200 years, while trees, which grow slowly at the beginning of life, can live up to 1,000 years.

“If fast-growing trees do not reach a significant age, they do not store large amounts of carbon in their wood for a long time. Under the influence of global warming, the increased growth of mountain forests in the areas under study will only lead to faster carbon turnover rather than to its storage in the biomass of old trees. The latter simply will not exist, ”- said the co-author of the study, Doctor of Biological Sciences, Alexander Kirdyanov, a leading research associate at the Krasnoyarsk Science Center SB RAS and Siberian Federal University, a visiting researcher at the University of Cambridge.

The study does not answer the question of how, with further climate change, all the forests on the planet will behave. After all, the study is concerned with only two high-mountainous areas and several species of coniferous trees. However, based on the obtained results, an important conclusion can be made: the assumptions on the possible self-regulation of the climate by the biosphere, for example, due to enhanced tree growth and absorption of carbon dioxide from the atmosphere, require careful verification.