Abstracts |
Polygonum viviparum is one of the first ectomycorrhizal (EM) plant species
colonising primary successional sites at the Rotmoos glacier forefront (Tyrolean Alps, Austria).
On a site with soil development of about 150 years (2,400 m above sea level), mycobionts of P.
Viviparum were identified by morphotyping and fungal ribosomal deoxyribonucleic acid internal
transcribed spacer sequencing. For studying seasonal dynamics and spatial heterogeneity,
ectomycorrhizae were sampled on five plots during all seasons. P. Viviparum root tips were always
EM. In total, 18 mycobiont taxa of the following genera were identified: Cenococcum (1),
Cortinarius (2), Helvella (1), Inocybe (3), Russula (1), Sebacina (2), Thelephora (2) and
Tomentella (6). All were non-specific EM partners of EM plants. As early as 2 weeks after spring
snow melt, EM were well developed, vital and showed high mycobiont diversity. The relative
abundance of senescent root tips was lowest in spring and increased throughout the year, with a
maximum in winter (frozen soil). Thus, mycobiont growth and physiological activity obviously
start when soil is still under snow cover: We speculate that water availability is one important
initiation factor for mycorrhizal development under snow cover, when temperatures still range
around the freezing point. Irrespectively of the season, most abundant mycobionts at this primary
successional site belonged to the genera Tomentella, Sebacina and Cenococcum, also in frozen
soil. Spatial heterogeneity was high when considering species composition and diversity indices.
Overall mycobionts species richness was restricted at this site, probably because of the limited
availability of fungal partners. We regard the presence/absence of fungal partner and limiting
abiotic impacts of the environment as key factors for the symbiotic status of P. Viviparum.
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