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 ʻAtropuniceaʼ 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. FUNGuild 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 demonstrate that the wood mycobiome of aging trees is neither static nor functionally neutral, but host-dependent and temporally dynamic. Short-term environmental variation may accelerate fungal succession inside wood, potentially influencing tree decline trajectories in managed historical park landscapes.