Fungi as potential factors limiting natural regeneration of pedunculate oak (Quercus robur) in mixed‐species forest stands in Poland

Abstract

Dieback of young Quercus robur seedlings can limit natural regeneration in mixed‐species forest stands in Poland. The aim of this study was to examine the role of fungi in the dieback of oak seedlings in central Europe. Fungi were isolated from the stems and roots of Q. robur, from both healthy seedlings and seedlings with symptoms, that were sampled from four stands in Poland. In total, 111 distinct taxa were identified. Ascomycota was dominant, representing 95.6% of the isolates. Among the taxa identified, Alternaria alternata, Colletotrichum fioriniae, Colletotrichum godetiae, Coniella quercicola, Diaporthe eres, Gnomoniopsis paraclavulata, Ilyonectria rufa, Mucor genevensis, Penicillium glandicola, Tubakia dryina, and Umbelopsis changbaiensis were most frequently isolated, and were consistently found in stems and roots of both healthy and diseased plants. The community compositions of fungi in healthy and diseased stems were similar, although Fusarium species, especially Fusarium sp. 1 (FTSC 5) and F. sporotrichioides, were found mainly in seedlings with symptoms. The pathogenicity of the most consistently isolated species from stems and roots of diseased seedlings was tested on Q. robur seedlings. F. sporotrichioides caused the largest lesions on inoculated seedlings. Six weeks after inoculation, D. eres, C. fioriniae, G. paraclavulata, T. dryina, and F. sporotrichioides killed 0%–18.8% of seedlings, while I. rufa and Ilyonectria pseudodestructans did not cause any lesions or other symptoms. This study is the first comprehensive report suggesting that massive fungal attack can lead to oak seedling dieback in mixed‐species forest stands in central Europe.

Deterioration in the Quality of Recalcitrant Quercus robur Seeds during Six Months of Storage at Subzero Temperatures: Ineffective Activation of Prosurvival Mechanisms and Evidence of Freezing Stress from an Untargeted Metabolomic Study

“…Climate change scenarios, particularly more severe droughts, will contribute to the greater future mortality of pedunculate oak trees [1]. Successful natural regeneration in oak forests depends on site fertility, soil moisture, overstory density, light availability, root competition from the parent trees, fungal diseases and, predominantly, seed production [2,3]. The interannual cycles of seed production in pedunculate oak range from 3 to Metabolites 2022, 12, 756 2 of 21 8 years [4] and are further disturbed by temperature differentials between consecutive years [5].…”

The culturable leaf mycobiome of Viscum album subsp. austriacum

“…paeoniae on mistletoe. As with oak seedlings (Jankowiak et al, 2022), F . paeoniae was isolated from healthy leaves of V .…”

“…and Populus sp. in China (Wang et al, 2022) as well as Quercus robur L. (Jankowiak et al, 2022), Fagus sylvatica L. (Stępniewska et al, 2021) and Populus tremula L. (Jankowiak, unpublished data) in Poland. Therefore, we suspect that F .…”

“…Pathogenicity tests are needed to determine the impact of F. paeoniae on mistletoe. As with oak seedlings (Jankowiak et al, 2022), F. paeoniae was isolated from healthy leaves of V. album subsp. austriacum, suggesting that this fungus may be endophytic on many forest plants.…”

Phytophthora species cause sudden and severe decline of naturally regenerated European beech (Fagus sylvatica) seedlings

“…For example, Jankowiak, Bilański, et al (2016) demonstrated that naturally regenerating silver fir seedlings can be infected by Gyoerffyella species, leading to seedling decline. In addition, fungal infection has been linked to the negative health of pendunculate oak seedling in mixed‐species forest stands in Poland (Jankowiak et al, 2022).…”