# Annual Dynamics of Mycobiota in Symptomatic Century-Old Trees of Aesculus hippocastanum, Fagus sylvatica, Populus alba, and Quercus robur

## TL;DR

This study explores how fungal communities in aging trees change over time, showing that these communities are influenced by tree species and vary significantly between years.

## Contribution

The study reveals host-dependent and temporally dynamic fungal community changes in aging trees, challenging the notion of static wood mycobiomes.

## Key findings

- Fungal diversity varied significantly among tree species and over time.
- Copper beech showed the strongest decline in fungal richness and increased beta dispersion.
- Saprotrophs and mixed pathotroph–saprotroph guilds dominated, indicating active wood degradation.

## Abstract

This study investigated the composition and temporal dynamics of wood-inhabiting fungal communities in four aging tree species in Lednice Castle Park (Czech Republic), located within the Lednice–Valtice Cultural Landscape, a UNESCO World Heritage Site. Forty wood cores were collected from 20 trees at two time points (2023 and 2024). The hosts included horse chestnut (Aesculus hippocastanum L.), copper beech (Fagus sylvatica ‘Atropunicea’ L.), oak (Quercus robur L.), and poplar (Populus alba L.), each exhibiting visual signs of decline. Fungal assemblages were profiled using ITS2 high-throughput amplicon sequencing. Ascomycota dominated across all hosts (72–89% of reads), while Basidiomycota contributed 8–24%, largely represented by Agaricomycetes in F. sylvatica. Alpha diversity varied significantly among hosts (Shannon: F3,36 = 10.61, p = 0.001 in 2023; F3,36 = 10.00, p = 0.001 in 2024). Temporal shifts were host-dependent: F. sylvatica exhibited the strongest year-to-year decline in richness (Chao1: −83%, p = 0.007) and increased beta dispersion, while A. hippocastanum and P. alba showed significant increases in diversity (+65% and +42%, respectively). Community composition was shaped by host species (PERMANOVA Bray–Curtis: p = 0.001) and shifted over time (Jaccard: p = 0.001), with F. sylvatica showing the highest temporal turnover. Functional guild analysis revealed consistent dominance of saprotrophs (29–41%) and mixed pathotroph–saprotroph guilds (23–36%) across hosts, indicating active degradation processes inside functional xylem. These results indicate that, within the studied system, the wood mycobiome of aging trees is host-dependent and temporally dynamic rather than static or functionally neutral. Short-term temporal turnover observed between sampling years may contribute to shifts in fungal community composition and succession within wood, with potential implications for tree decline processes in managed historical park landscapes.