Our aim is to evaluate the changes in arbuscular mycorrhiza characteristics of winter wheat in a three-year experiment. Study results show that fertilizers produce strong variations in arbuscular mycorrhiza extension, with colonization frequency values within 76–98%. The intensity of colonization is only 12% when phosphorus (P) exceeds nitrogen (N) in autumn, but reaches 38% when the N:P ratio is equal. Root colonization shows no consistency from one experimental year to another, with the largest fluctuations recorded in colonization intensity (22–65%) and arbuscules abundance (0–5%). Arbuscules are maintained below 1% by fertilizer with more P than N. Colonization forecasting models indicate P as a factor for the reduction of symbiosis. Each kg of applied P can reduce the colonization frequency by 0.28% and intensity by 0.37%. The maximum of the colonization degree is 61% due to the synergy of equal N and P doses in autumn and ammonium nitrate applied in spring. The application of multiple moderate doses acts as a stimulant for the development of a large root-fungal interface.

Ecosystems with high natural value (HNV) have generally been maintained by agricultural practices and are increasingly important for the ecosystem services that they provide and for their socio-economic impact in the ever-changing context. Biodiversity conservation is one of the main objectives of the European Green Deal, which aims to address biodiversity loss, including the potential extinction of one million species. The aim of this research was to trace the effects of organic and mineral fertilizers on the floristic composition, but also on the number of species, of the grasslands with high biodiversity (HNV) from the Transylvanian Plain, Romania. The experiments were established in 2018 on the nemoral area and analyzed the effect of a gradient of five organic and mineral treatments. Fertilization with 10 t ha⁻¹ manure or N₅₀ P₂₅K₂₅ ensures an increase in yield and has a small influence on diversity, and it could be a potential strategy for the maintenance and sustainable use of HNV grasslands. Each fertilization treatment determined species with indicator value that are very useful in the identification and management of HNV grasslands. The dry matter biomass increases proportionally as the amounts of fertilizer applied increase and the number of species decreases.

Reynoutria japonica Houtt (RJ) is an extremely invasive plant species, found nowadays in a wide range of habitats, including those polluted with heavy metals (HM). The aim of this study was to investigate HM dynamics in RJ–soil interactions in five habitats historically polluted with HM located in Baia Mare city, Romania. The concentrations of major metal elements (Cd, Cu, Pb, Zn) in plant tissues (roots, stems, leaves) and soil samples collected from the study sites were analyzed via portable ED-XRF spectroscopy (converted), and the translocation factor (TF) and bioconcentration factor (BCF) were calculated. The mean values of HM in soil samples collected from the study sites exceeded the threshold limit values established by Romanian legislation. Generally, the highest concentration of Cd was recorded in the above-ground part of the plant (stem and leaves), while for Cu, Pb and Zn, the highest values (with few exceptions) were recorded in the root. The metal transfer was highly effective from soil to RJ, such that all four of the HM studied exceeded the normal range of metals in a plant. Analysis of metal concentrations in plant tissues showed an efficient movement of Cd and Zn to the above-ground parts of the plant, a tendency particularly pronounced in the case of Cd (TF and BCF > 1), while Pb was the least bioaccumulated HM. It may be concluded that RJ is able to tolerate high concentrations of HM, being a good phytoextractor for Cd and Zn.

Exploring grassland microbiomes is a challenge in the current context of linking soil microorganism activity with the balance of these ecosystems. Microbiologists are constantly attempting to develop faster and lower-cost methods, and propose new and best-fitted indicators that will provide a more complex data analysis. A different concept was proposed for assessing functional microbiomes by splitting the functional ecological niche into complementary segments. The comparison with the upper and lower limits of the ecological niche provides a clearer image of community alterations due to long-term applied treatments. The method allows the extraction of the most sensitive and stable functional guilds, with the extraction of the most critical dominant–codominant functional groups in every segment of the functional niche. The resulting microbial functional–sociological model is ready to use on community-level physiological profile databases and also can be applied backward for vegetation analysis.

Long-term fertilization targets mycorrhizal fungi adapted to symbiotic exchange of nutrients, thus restricting their colonization potential and re-orienting the colonization strategies. The MycoPatt tool has a high applicability in quantifying the symbiotic process with the identification of mycorrhizal indices and projection of mycorrhizal patterns. Organic treatments increase the symbiotic process, visible in values of colonization frequency and intensity, with about 6% more than the native status of colonization. At the opposite pole, organic-mineral treatments decrease the colonization parameters by up to half of the organic treatment. All of the colonization parameters show significant correlations, except for the arbuscules/vesicle ratio (0.03). All the applied treatments, except for the organic one, record multiple root segments with a colonization degree lower than 10%. The application of treatments changes the strategy of native colonization from a transfer (40%) and storage (37%) to a predominant storage (50%) for organic treatment, and are mainly proliferative between 38–50% in mixed and mineral treatments. The high amount of mineral components increases also the presence of resistance conditions strategies. The use of mycorrhizal pattern maps, with the inclusion of colonization strategies, presents an important direction in understanding the evolution of mutual relations, and to explore in-depth the efficiency of the whole symbiotic process.

Festuca rubra is one of the dominant species in mountain high natural values grasslands. Most herbaceous plants are involved in a symbiotic partnership with arbuscular mycorrhizas for maintaining their abundance and cover. This research was conducted to explore the changes in mycorrhizal colonization patterns and structure development due to the long-term application of treatments. A large database of microscopic images was deeply analyzed with the MycoPatt tool, for the extraction of clear mycorrhizal maps that present particular colonization strategies. The overall colonization frequency and intensity varied largely between treatments, with a maximum in organic conditions. The presence of both arbuscules and vesicles in the same root area indicate a continuous alternance of fungal strategy, from storage to enhanced transfer of nutrients. A low-mineral organic treatment permits a clear separation of colonization strategy in different parts of roots. The nutrient availability due to mineral treatment induced a restriction in mycorrhizal development, which was maintained colonization by a resistance conditions strategy. The use of mycorrhizal maps permits a deep scanning of colonized roots, identifying the real positioning of fungal structures, along with their developmental potential and the assessment of the colonization strategy.