Dynamics of photosynthetic pigments in the main forest-forming trees of the carbon polygon "Ural-carbon"

Abstract

Increasing of the greenhouse gases in the atmosphere and global warming have led to the creation of a network of carbon polygons in Russia, which are entrusted with the mission of assessing, accounting, and finding technological solutions in order to reduce the amount of these gases in the atmosphere. The Ural-Carbon polygon was created in the fall of 2021, and currently includes two sites, where the main forest-forming species grow. The first is characterized by fir-spruce and spruce-fir forests, the second - by light coniferous forest of the southern taiga type. To assess the potential contribution of the Middle Urals forests to CO2 fixation, the dynamics of photosynthetic pigments in the needles of the first-year shoots was evaluated in three conifer species. The content of photosynthetic pigments was determined from June to October 2022 spectrophotometrically in ethanol extracts. It was shown that in Pinus sylvestris, the formation of the first year needles began later than in Abies sibirica and Picea abies. Despite the later formation, the content of chlorophylls and carotenoids in the needles grew exponentially and reached almost the same values for all three species in August. In all species, the maximal content of photosynthetic pigments was found at the beginning of autumn, therefore, it can be assumed that at that time the potential ability of conifers to fix CO2 is maximal, but in reality photosynthesis can be limited by weather conditions. Comparing the data received in 2022 with the results obtained earlier, it can be assumed that, under conditions of increasing temperature and CO2 concentration in the atmosphere P. sylvestris will more effectively fix carbon dioxide than A. sibirica and P. abies. It was shown that in the first year needles there was an advanced accumulation of carotenoids in comparison with chlorophylls with age, which can protect the photosynthetic apparatus from photooxidation in winter.