Variability of morphometric traits of <i>Hypogymnia physodes</i> (L.) Nyl. growing on <i>Betula pendula</i> with different positions on the trunk and in the relief

The article examines the variability of quantitative morphological traits of the epiphytic lichenHypogymnia physodes. The studywas conductedin the Republic of Mari El in a mixed-herb birch forest located at the base and middle of a slope, with a 6-meter elevation difference between habitats. In each habitat,H.physodesthalli at ontogenetic states v₁-g₃v were collected from silver birch (Betula pendula) trees at two heights: 0–0,5m and 0,5–2,0m. Six morphometric traits were studied. A three-factor ANOVA (habitat, height on the trunk, ontogenetic state)was usedto compare the traits. All morphometric traits differed across ontogenetic states. The varying positions of trees along the slope influenced only the thallus diameter ofH.physodes, with the largest sizes observed at the wetter and less illuminated base of the slope. The least variable trait was the number of thallus lobes. Thallus diameter, the number and diameter of lip-shaped soralia, and the diameter of helmet-shaped soralia were greater at a height of 0–0,5m. Several morphometric traits respond to microclimatic changes in the slope and tree trunk across specific ontogenetic states.