Scots Pine Generative Sphere as an Indicator of the Climate-Determined Change in Vital States of the Populations

Abstract

The problems of transition of Scots pine (Pinus sylvestris L.) from the stable state to an unstable equilibrium and the change of equilibrium population to non-equilibrium as a result of the global warming are discussed. The purpose of the research is to study the state of the southern and central forest-steppe Scots pine populations’ generative sphere on the basis of its seed fullness, assess their vital state in 2020 compared to 2016 – the year of the pine forests’ destabilisation, as well as compared to the state of the steppe populations in the abundant year of 2017. The objects of the study were the central and southern forest-steppe pine populations growing in the ecologically favourable territory of the Voronezh and Belgorod regions. In 2015, their transition from equilibrium to a slightly nonequilibrium systems was recorded. The level of seed fullness in the Stupino and Belgorod populations decreased by 25.6 and 24.6%, respectively, the number of seeds by 37.7 and 22.4%, and the mortality rate of ovules increased by 3.9 and 4.0 times. Comparison of the seed productivity indicators in 2013, 2016 and 2020 showed that at present both plantations can be considered equilibrium systems. The central population has returned to the regional norm (stable equilibrium), the southern one is in a state of unstable equilibrium. The analysis of variance revealed a significant (57.8%) influence of the HTC factor on the generative sphere of the Belgorod population on the basis of full grain. In the last decade, the number of optimal years in the CCR has decreased from 7–8/10 years to 5. It takes 3 optimal years to return pine forests to equilibrium. High rates of the global warming can lead to an imbalance and re-destabilization. A further reduction in the number of optimal years makes it almost impossible for pine forests to return to the regional norm.