Photosynthetic apparatus state and oxidative stress level in needles of Abies sibirica L. at different stages of tree dieback infested with the four-eyed fir bark beetle (Polygraphus proximus Blandford) in forest stands of the Perm Krai
M.A. Shelyakin, E.V. Garmash, E.V. Silina, K.V. Yadrikhinsky, E.E. Rotermel, L.A. Ivanchina
Section: Population ecology
The invasive stem pest, four-eyed fir bark beetle Polygraphus proximus, drives the Abies sibirica L. massive dieback in the Russian taiga zone. Early detection of infestation hotspots requires the development of rapid remote sensing methods and novel vegetation indices sensitive to changes in the physiological and biochemical parameters of needles. Research was completed across 15 sites in coniferous-broadleaf forests in the Perm Krai. The following categories of fir tree sanitary condition (CSC) were identified: healthy (I), weakened (II), severely weakened (III), dying (IV); and
among dead trees: recent deadwood (V) and old deadwood (VI). We assessed the photosynthetic apparatus state in the needles by photosynthetic pigment content and chlorophyll fluorescence parameters. Oxidative stress level was evaluated by measuring H2O2 and lipid peroxidation products concentration in the needles. In the needles of the I–III CSC trees, with increasing desiccation rate, chlorophyll fluorescence parameters reflecting the efficiency of light energy using
(Fv/Fm, ΦPSII, ETR) tended to decrease while photosynthetic pigment content and ratios were stable. Concurrently, the non-photochemical quenching coefficient (NPQ) and pro-oxidant content slightly increased, indicating a mobilization of protective mechanisms. Significant damage of the photosynthetic apparatus, characterized by chlorophyll degradation, weakened photosynthetic activity, and increased oxidative reactions, was recorded in the dying trees’ (CSC IV)
needles. In the needles of dead trees (V–VI), pigment content dropped sharply, photosynthesis ceased, and pro-oxidant level declined markedly, indicating the cessation of vital processes. Prospects for using parameters of the photosynthetic apparatus and the pro-oxidant status of fir needles are outlined for creating remote monitoring models based on the spectral reflectance of tree crowns.
ISSN 1995-4301
Select viewing options
