Abstract
Forest fire represents one of the most serious abiotic stress factors that influence the function and productivity of ecosystems globally. Siberian pine forests are often exposed to forest fires, but they are not always harmful to them. This paper discusses the possibility of using fluorescent methods to assess the thermal effects on the assimilation apparatus of Scots pine (Pinus sylvestris L.) needles. The assimilation apparatus of pine needles was reestablished after exposure to convective, simulating the effect of ground fire heat flow, though the recovery rate depends on the impact force. The analysis of fast and delayed fluorescence characteristics revealed differences in the thermostability of the Scots pine needles showing certain modification of physiological processes in plants under the influence of stress factors with a positive acclimation effect. The Scots pine needles grown after ground fire are more resistant to the recurrent sublethal temperature, and this effect is maintained during the next growing season. This paper suggests that reforestation planning, particularly burning (low-intensity fire), will result in improved tree physiology that will lead to an increase in Scotch pine survival rate due to repeated heat stresses. Furthermore, the fluorescence method can be used to diagnose the thermic resilience of pine needle and assess high-temperature effects.