Mycorrhizal macrofungi play an important role in plant physiologicalcondition and help protecting their hosts from biotic and abiotic stress and pathogens.At the research area in Istria, western Croatia, pathogenic fungus Sphaeropsissapinea (Fr.) Dyko et Sutton has caused substantial damage in Austrian pine (Pinusnigra J. F. Arnold) plantations through the last 25 years. During the previous researchactivities on predisposition to S. sapinea infections, site and stress conditions weredetermined as key factors. Back then, existing differences in fungal communities atdisturbed and healthy Austrian pine plantations were observed. We hypothesized thatAustrian pine plantations with higher ratio of ECM species and their sporocarps(minimum 40% of ECM species) are less susceptible to S. sapinea infection.Furthermore, they have lower crown transparency percentage and higher levels ofpotassium (K) in one- and two years old needles. Also, we tested species richness anddiversity indices as an Austrian pine health status indicators. This is the first researchon linkage between ECM species and S. sapinea infection rate on Austrian pineneedles.Fungal samples were collected on three different permanent research plotsof 400 m2 each, for three consecutive years (2011-2013) from week 36 to week 50,every fortnight. Additional six plots were added in 2013. All samples were recordedwith digital camera. Each fungal species and all its sporocarps on the plot representedone sample. They were collected in a wax paper bags, assigned and processed inlaboratory on the same day. Sporocarps were counted and dried for 48 hours at 35-40C. Afterwards, they were packed in plastic bags and deposited to Croatian NationalFungarium (CNF) for further identification. For all plots we analyzed soil samplesand recorded soil profiles. For all plots, plant communities were recorded in 2014, inApril and June.Symptomatic branches and needles were taken from one tree per plot toanalyze S. sapinea presence and number of pycnidia. Each tree was represented withfive branches and 20 needles (100 needles per plot). Crown transparency wasassessed for all trees on plots according to ICP Forest methodology. Needles fornutrients analyzes were collected from five trees scattered across the plantation. Oneyear old and two year old needles were collected and processed separately. Nitrogen(N), potassium (K) and sulfur (S) were analyzed.All collected data were analyzed with Statistica 10 software and PAST 3.06software. Kruskal-Wallis ANOVA, linear regression and correlation analyzes werecarried out. Shannon index (H), Simpson index (D) and Evenness (E) wereIXcalculated to compare biodiversity on research plots.Soil analyses defined three different soil types: Tera Rossa (plots MaliGolji and Trošti), Calcocambisol (plots Trstenik, Lovranska Draga, Ripenda andKurbino brdo) and Eutric Cambisol on flysch (plots Previž, Lesišćina and Paz).During the three year survey on three plots, 2814 sporocarps (2288 ECM)and 88 species (47 ECM) were recorded, belonging to 37 genera. The maximumspecies richness was found at plot Trstenik (44 species), while the highest sporocarprichness was recorded at plot Previž. Results from data obtained on nine plots only in2013 showed different species richness distribution. Plot Trošti was the most rich infungi species (35), and was followed by plots Trstenik (34) and Lesišćina (33). Atplots Lovranska Draga and Paz only 15 species were recorded. The highest numberof sporocarps was recorded on plot Previž (1422), then Ripenda (407) and Trošti(361). The lowest sporocarp number was recorded at plot Lovranska Draga (58), thenPaz (123) and Mali Golji (161). In total, at 2013, 3377 sporocarps were recorded,belonging to 124 fungal species and 48 genera.Sphaeropsis sapinea pycnidia were not found at plots Previž and Lesišćina,while they were abundant at plots Trošti, Kurbino brdo and Mali Golji. On analyzedneedles, together with S. sapinea, we found present Truncatella hartigii (Tubeuf)Steyaert. Plots with highest share of ECM species (Previž, Lesišććina and Paz) werefree of pycnidia or we found only few per needle. An opposite situation occurred onplots with low share of ECM species and sporocarps (<30%), where S. sapinea wasabundantly present together with higher crown transparency. Shares of ECM speciesand sporocarps were strongly related to an average number of S. sapinea pycnidia ona single needle and to crown transparency. Linear regression trends were statisticallysignificant at p<0,05. Between studied variables, strong and statistically significantcorrelations were present. Potassium level in one- and two- year old nedlees wasuneaqual among differently infcected plots. Nitrogen and sulfur content was loweston healthy plots at flysch bedrock and highest at severly infected plots. N:K ratio waslowest at most healthy most infected plots as well. Nitrogen content showedstatistically significant and relatively strong correlation with number of picnidya onnedlees and percentage of crown transparency. Potassium content showed a relativelyweek correlation towards studied variables.Several ECM species with assumed mycobioindication value were recordedat plots Previž and Lesišćina only, e. g. Tricholoma caligatum (Viv.) Ricken, Suillusmediterraneensis Jacquet. & J. Blum) Redeuilh, Hydnum albidum Peck, Hydnellumferrugineum (Fr.) P. Karst., Phellodon niger (Fr.) P. Karst. and Cantharelluslutescens (Pers.). In this study, seven fungal species (Boletopsis grisea, Galerinabadipes, G. vittiformis, Lyophyllum aemiliae, Ramaria decurrens, Tricholoma focale,T. stans), were recorded for the first time in Croatia. Shannon and Simpson indicesand Evennes showed no correlation towards variables representing plantation healthstatus nor did species richness.According to obtained results, plots Previž, Lesišćina and Paz werecharacterized as not disturbed (affected), plots Trstenik, Ripenda and LovranskaDraga were characterized as moderately disturbed, while plots Trošti, Kurbino brdoand Mali Golji were characterized as severely disturbed. We confirmed ourhypothesis that ECM species and sporocarp ratio are reliable indicators of Austrianpine plantations health status. This was further confirmed by numerous indicatorfungal species recorded only at healthy plots. Diversity indices and species richnessare not reliable indicators of Austrian pine plantations health status.XThis research continues on previous research at the same Austrian pineplots on predisposition to S. sapinea infections, where site and stress conditions weredetermined as key factors. Our results confirm the assumption that stands with higherS. sapinea infection rate have impoverished mycorrhizal community and revealpotential indicator species of more resistant and healthy habitats. Since this researchbrings out results that cannot be compared with other studies, we must interpretobtained results with precaution. To gain more reliable and precise results, furtherresearch based on higher number of plots, longer survey period and more detailedanalysis of habitat factors is needed.