Dynamics of radial increment and carbon sequestration of pine forests (Pinus sylvestris L.) affected by recreational stress and climate change in the forest steppe, Voronezh region, Russia

The aim was to assess the influence of climatic factors and recreation on the dynamics of radial increment and carbon sequestration in the stem wood of Scots pine in the environment of the forest-steppe region of Voronezh, Russia. The research was carried out in the Usmansky Bor, Voronezh region. Sample plots were established in 105-145-year-old pine stands at different stages of recreational degression to study the anthropogenic impact on pine forests. Cores were taken from 120 trees in the sample plots and analysed. We analysed the cyclical dynamics of radial increment, relationships with climatic factors, assessed the strength of the influence of climatic parameters on increment and calculated annual carbon sequestration. A significant decrease in radial increment of tree stands in late degression stages and a violation of increment cyclicity was observed. A strong positive relationship between atmospheric precipitation and incremental indices was found in spring-summer months (r = 0,50, p < 0,05). Trees that survived recent drought and were not affected by wildfire in 2010 showed a significant and prolonged depression in stem growth, which had not completed even after five years of adverse environmental factors. When anthropogenic recreational pressure is combined with the effects of adverse climatic factors, the degradation of pine stands increases significantly. This combination of factors leads to even more significant changes in forest productivity. At the same time, the carbon sequestration capacity of the trees decreases significantly as the stage of degradation progresses. The main limiting factor for pine in the forest-steppe zone is precipitation but the total influence of climatic factors was more significant than the individual effects of each of them.