True slime mould assemblages respond acutely to microhabitat structure, which may constitute potential indicators of forest dynamics; however, large-scale syntheses integrating habitat scale and substrate specificity remain exceedingly scarce. By collating 3085 occurrence records into eight ecologically coherent habitats and ten substrate guilds, we quantified richness, entropy, turnover and indicator strength via rarefaction, Chao1/ACE, Shannon–Simpson indices, $\beta$-diversity partitioning, NMDS, PERMANOVA and ${\mathit{IndVal}}_g$ analysis. Broadleaved deciduous forests accounted for 37.9% of observations and hosted the most taxa, while lignicolous samples in both deciduous and bog–mire contexts dominated species counts; open grasslands were compositionally depauperate. Species replacement, not nestedness, structured assemblages (${\beta }_{\mathrm{SIM}}/{\beta }_{\mathrm{SOR}}\approx 0.82$), and habitat plus substrate explained two-thirds of variance. Indicator analysis isolated six habitat-diagnostic genera (notably Cribraria, Hemitrichia and Licea) and, at species resolution, highlighted Diderma niveum, Fuligo septica and Ceratiomyxa fruticulosa as high-fidelity bioindicators of montane grassland, bog–mire and broadleaved forest conditions, respectively. Taken together, our findings lay the groundwork for employing true slime moulds to identify habitat types and assess their ecological condition, while underscoring the conservation value of dead wood retention and structural heterogeneity. The benchmarked indicator set we provide enables rapid assessments and establishes a temporal baseline for tracking climate- and management-driven change in Central European Eumycetozoa diversity.

European armillarioid fungi (Armillaria and Desarmillaria) are white-rot fungi with soilborne pathogenic potential on woody hosts and clear relevance to forest pathology. This structured narrative review synthesizes the reported chemical composition of European armillarioid taxa across wild basidiocarps, infected host material, and laboratory-derived matrices, with emphasis on metabolites and biochemical traits that can be interpreted in a forestry context. The available evidence is taxonomically and methodologically uneven and is dominated by A. mellea and A. ostoyae, whereas infected host material remains less well characterized than culture-derived and basidiocarp-derived material. Protoilludene-derived aryl esters provide the clearest compound-resolved evidence for antifungal and phytotoxic activity across controlled assay systems, but these data derive from distinct experimental formats that are not directly comparable as a single potency scale, while lipid profiling offers the strongest support for chemistry-based diagnosis from infected material. Overall, current evidence supports forestry interpretation, diagnostic profiling, and selective screening of culture-derived metabolites, but practical application remains constrained by matrix dependence, taxonomic gaps, and the limited transferability of in vitro findings to forest conditions.

The Knyszyn Forest is one of the major lowland forest complexes of north-eastern Poland, yet its myxobiota remains insufficiently documented. We surveyed Eumycetozoa in three forest nature reserves—Krzemianka, Jałówka, and Las Cieliczański—to assess local species richness, substrate occurrence, and new distributional records. Field surveys were combined with moist-chamber cultures, and species were identified from mature sporocarps using macro- and microscopic morphology. The inventory yielded 761 occurrence records representing 80 identified taxa. Moist-chamber cultures produced more records and species than field collection, while field surveys detected taxa fruiting naturally during the study period; together, both methods produced a more complete inventory than either method alone. Three species, Paradiacheopsis solitaria, Macbrideola rutilipedata, and Licea operculata, were recorded for the first time in Poland; these national novelties were included among the 14 taxa recorded for the first time in north-eastern Poland. Most records came from dead wood and bark, although other dead organic substrates also contributed to the recorded substrate spectrum. The resulting dataset provides a regional baseline for future biodiversity surveys in the Knyszyn Forest.