Оценка влияния старовозрастных ельников на углеродный баланс таежных лесов Валдая

Abstract

Monitoring the photosynthesis- and respiration-related characteristics of the old-aged forests of the Valday Region is of paramount importance since it is imperative that the role of all factors contributing to their carbon balance should be evaluated. This work presents data on seasonal dynamics of midday carbon-dioxide exchange and photosynthetic productivity of the Norway spruce (Picea abies L.) in May - October 2018-2020. It was established that the main factors determining the CO2 assimilation rate of the spruce are the air temperature and illumination. The average annual photosynthesis intensity level was more than two times higher than the light-dependent respiration level. Significant interseasonal changes in spruce photosynthetic productivity were revealed: the maximum and minimum photosynthetic productivity was detected in June-July and October, respectively. The interannual changes were related to the weather conditions and to the state of the forest stand in the tested area. The total carbon dioxide uptake by spruce needles in 2018, 2019, and 2020 was 3.3, 2.13, and 1.15 ton of CO2∙ha-1∙year-1. The average value of net primary production (0.37 ton of C∙ha-1∙year-1) and the positive carbon dioxide balance of the Norway spruce testify to a considerable influence of old-aged spruce forests on the carbon balance of the forest cenoses of the Valday Region.