Application of fluorescence analysis for evaluation of heat stability of Scotch pine needles after ground fires

Abstract

This paper discusses the possibility of using fluorescent methods to assess the thermal effects on Scots pine needles’ assimilation apparatus. Two types of experimental studies were carried out. The assessment of the primary heat resistance of the needles from the forest stand previously unaffected by fire lies at the heart of the first one. To assess the effect of temperature stress on the pine needles’ photosynthetic apparatus functioning, the experiments on modeling a convective flow, simulating the ground fire effect were carried out. The second year needles from the 1st class trees of the green moss-and-motley group of forest types located in the forest-steppe zone of Southern Siberia were studied. According to Fv / Fm fast fluorescence parameter (the maximum photochemical quantum yield of photosystem II), it was demonstrated that after the heat stress, the assimilation apparatus of pine needles can be restored at different rates. This rate depends on the duration and intensity of heating. The second experiment was based upon the task of determining the ability to restore the assimilation apparatus of pine needles after the repeated influence of sub-lethal temperatures on plants in the recovery period after a ground fire of the previous year. Based on the analysis of the parameters of fast and delayed fluorescence, it was possible to detect differences in thermal resistance and the rates of pine needles’ photosynthetic activity reestablishment, which indicates modification of physiological processes in plants under the influence of the thermal stress factor, forming a positive acclimation effect. Thus, fluorescent methods can be used to diagnose the thermal resistance of needles. In particular, the indicator of delayed fluorescence as a criterion for assessing the resistance of the assimilation apparatus in response to the repeated action of stress factors during the recovery from fire. Fv / Fm ratio can be used to assess the response of the needles’ assimilation apparatus to stress during the first days after fire.

Keywords

• Scotch pine Pinus sylvestris L.
• heat stability
• forest fires
• fluorescence
• heat stress
• Southern Siberia