High nature value (HNV) grassland systems are increasingly important for the ecosystem services they provide and for their socio-economic impact in the current constant-changing context. The aim of our paper is to evaluate the long-term effect of organic fertilizers on HNV systems in the Apuseni Mountains, Romania. As an objective we want to identify the optimal intensity of conservation management and its recognition based on indicator value plant species. The experiments were established in 2001 on the boreal floor and analyze the effect of a gradient of four organic treatments with manure. Fertilization with 10 t ha−1 manure ensures an increase in yield and has a small influence on diversity, and could be a real possibility for the maintenance and sustainable use of HNV. Each fertilization treatment determined species with indicator value that are very useful in the identification and management of HNV. The indicator species are useful in forecasting the fluctuations and successions in grasslands, determined by the modification of the dominance-codominance ratio and the real coverage of each species.

The harmonization of methodologies for the assessment of radicular endophytic colonization is a current necessity, especially for the arbuscular mycorrhizas. The functionality of mycorrhizal symbionts for plants can be described only by indicators obtained based on microscopic analysis. That is the reason for which a unifying methodology will lead to the achievement of highly correlated indicators comparable from one research to another. Our proposed methodology can further digitize the microscopic observations of colonization. The MycoPatt system is developed as a methodological framework for obtaining objective and comparable microscopic observations. The horizontal, vertical and transversal indicators are highly adaptable and allow the tracking of mycorrhizal colonization in root length. All structures developed by symbionts can be traced and the obtained metadata can be compared without any transformation. Mycorrhizal maps have a high degree of applicability in evaluating soil inoculum efficiency. In the future, the application of this method will lead to digital maps with a high degree of accuracy. MycoPatt allows the mathematical expression of colonization patterns, being a complex model that converts biological data into statistically comparable indicators. This will further allow obtaining inferences with applicative importance and similarity spectra for the colonizing fungi and host plants.

Grassland ecosystems occupy significant areas worldwide and represent a reservoir for biodiversity. These areas are characterized by oligotrophic conditions that stimulate mycorrhizal symbiotic partnerships to meet nutritional requirements. In this study, we selected Festuca rubra for its dominance in the studied mountain grassland, based on the fact that grasses more easily accept a symbiotic partner. Quantification of the entire symbiosis process, both the degree of colonization and the presence of a fungal structure, was performed using the root mycorrhizal pattern method. Analysis of data normality indicated colonization frequency as the best parameter for assessing the entire mycorrhizal mechanism, with five equal levels, each of 20%. Most of the root samples showed an intensity of colonization between 0 and 20% and a maximum of arbuscules of about 5%. The colonization degree had an average value of 35%, which indicated a medium permissiveness of roots for mycorrhizal partners. Based on frequency regression models, the intensity of colonization presented high fluctuations at 50% frequency, while the arbuscule development potential was set to a maximum of 5% in mycorrhized areas. Arbuscules were limited due to the unbalanced and unequal root development and their colonizing hyphal networks. The general regression model indicated that only 20% of intra-radicular hyphae have the potential to form arbuscules. The colonization patterns of dominant species in mountain grasslands represent a necessary step for improved understanding of the symbiont strategies that sustain the stability and persistence of these species.

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.

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.

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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.

The present paper aims to follow the behaviour of a forage mixture with red clover in the fourth experimental year. We followed the behaviour of a complex mixture consisting of Trifolium pratense (15%), Lolium perenne (20%), Festulolium (25%), Festuca arundinacea (25%) and Phleum pratense (15%) under the influence of mineral fertilization in the climatic conditions specific Plateau of Transylvania, Romania. Experience was installed in the spring of 2012 in experimental fields located inside the Agricultural Research and Development Station Turda. The mixture was sown on 2 densities namely 12.5 cm and 25 cm distances between rows and they were fertilized in early March with complex NPK and ammonium nitrate (33.3%) in four different doses: V1 -control variant, unfertilized, V2-N50P60K80, V3-N75P60K80 and V4 -N100P60K80. An interesting evolution of the forage mixture was observed in the fourth experimental year. Fertilization with N75P60K80 seemed to have a favourable influence on forage mixture productivity.