Investigations comprised two stands of Ass. Danthonietum calycinae on Mount. Kopaonik at 1150 and 1200 m. alt. In those stands, weight share of medicinal plants was monitored in the structure of grassland yields: in 1^st one (location Plekovište) under conditions of treatment with different amounts of fertilizers (1. Control, 2. PK, 3. NPK, 4. stable manure) and in 2^nd one (location Ilinac) at applying identical amounts of fertilizers (N₁₄₀P₆₀K₆₀) and at different systems of utilization i.e. by grazing (continuous and rotational) and cutting. The results were compared with a control variant i.e. without fertilizer application. Investigations were carried out during 1989-1991 at the first location and during 1991-1993 at the second one.

The results indicate that the share of medicinal plant species varies, depending on different fertilizer treatments and manner of utilization as well as per year. The application of NPK fertilizers decreased per cent of medicinal plants' share in the structure of grassland yield (3%), but the amount expressed in kg/ha was increased, concerning that total yield was increased (462.0 kg/ha). Quite contrary are findings in PK and manure treatments where relative share was 6% and 5.7%, respectively, and yield amounted to 444.0 and 421.8 kg/ha, respectively. The share of these species was higher in rotational than in continuous grazing and cutting.

Key words: fertilizers, medicinal plant, natural grassland, utilization.

An important resource from which a livestock feedingstuff can be produced is natural grassland. In Serbia 1,620,000 hectares are under grassland accounting for approx. 28% of agricultural land. In Central Serbia the area covered by natural grassland is even larger (1.220.000 ha) and its share amounts to 40% of the total agricultural land. The higher the altitude the greater its share, so in hilly-mountain areas grassland is a dominant type of vegetation.

The extent of natural grassland utilization decreases each year, which is the consequence of reduced livestock production, depopulation of regions where grassland prevails, reduced farm practices, fertilization in particular. All these processes result in increased biodiversity of plant species in plant communities. The application of farm practices, on the other hand, first of all fertilization, changes grassland floristic composition (Mrfat-Vukelić, 1987, 1991) and most frequently reduces the number of species in it.

Under conditions of thus opportune processes, the investigations presented herein were conducted. Their aim was to establish the presence of plants with medicinal properties in different systems of fertilization and natural grassland utilization and to compare the results with those obtained for plots where no treatments were applied i.e. with control.

Ass. Danthonietum calycinae is one of the most widely distributed associations in hilly and hilly-mountain regions. Investigations comprised two stands of the said association, growing on the north side of Mt. Kopaonik, where the share of medicinal plants in the structure of grassland yield was monitored. At the Plekovište location we monitored the effects of fertilization treatments on changes in weight share of medicinal plants. The treatments applied were as follows: Control, P₈₀K₈₀, N₈₀P₈₀K₈₀, and Manure - 30 t/ ha. The investigations were carried out in the 1989-1991 period.

At the second location (Ilinac) throughout the 1991-1993 period the treatments applied were: Rotational grazing, Continuous grazing, Frequent cutting, Non-frequent cutting, and Control.

Sheep were the grazing animals. On experimental plot N₆₀P₆₀K₆₀ was applied in springs, while N₄₀ was applied twice i.e. after the first and second cuts. Mineral fertilizer was not used on control plot.

Braun-Blanquet scale was employed to survey the degree of plant number and cover. Weight share was determined by separating the species in fresh state, by weighing them and by mathematical calculations of their per cent. Per cent of plant share was multiplied by green mass yield to obtain the amount of medicinal plants per 1 hectare. The share of medicinal species was monitored in the first cut, and sampling was done in 5 cutting terms, every 7 days, in 3 replicates. The results show only mean three-year values. Identification of medicinal plants i.e. of those, from floristic composition, having medicinal properties, was done according to the monograph "Medicinal Plants of Serbia" (published by the Division for Natural and Mathematical Sciences of the Serbian Academy of Sciences, Editor: M. Sarić, Belgrade, 1989).

Floristic composition of medicinal plants and the degree of their number and cover in the investigated stands are presented in Tab. 1.

It is noticeable from Tab.1 that ass. Danthonietum calycinae abounds in medicinal plants. Sixteen plant species are present at the Plekovište location and fifteen species at the Ilinac location. Unwillingly or not at all do farm animals graze most plant species of the said association, such as: Filipendula hexapetala, Thymus serpillum, Galium verum, Genista sagittalis, Carlina acaulis and others. However, some plants are harmful to farm animals like Stachys officinalis, Hypericum perforatum, Euphrasia stricta, etc. Of these, some plant species have marked medicinal properties and have been in use in folk medicine since times immemorial. They also play important role as raw materials in pharmaceutical industry.

Weight share of medicinal plants in the structure of grassland yield also varied depending on the system of fertilization and utilization (Tables 2 & 3). In addition, within the same treatments, the share of medicinal plants was non-uniform in all study years due to non-uniform distribution of precipitation.

At the Plekovište location (Tab. 2) the share of medicinal plants ranged from 3.0 - 6.1% i.e. from 269.5 - 462.0 kg/ha. The lowest per cent of plant share occurred when NPK fertilizer was applied. It ranged from 1.8-3.9% (3.0%, on average). This results from suppression of plants that are conditionally considered to be weeds in natural grassland and medicinal plants are most often found among them. Namely, a volume of results reported in previous investigations (Mijatović and Pavešić-Popović 1972, Stošić et al. 1989, Lazarević, 1991) showed that N fertilizer application intensifies the development of species of Poaceae family whose members, for the most part, do not possess medicinal properties. However, the application of NPK fertilizers produced the highest amount of medicinal plants per hectare (462.0 kg/ha), which is evidenced by the highest amount of plant mass obtained in this treatment.

The highest share of medicinal plants was in plots treated with manure and PK fertilizers, primarily due to increased share of the species Genista sagittalis and Primula elatior. Although the relative share of medicinal plants in these treatments was twice as much than that in NPK treatments, the amount of plant mass per hectare was lower (444.0 kg/ha in PK treatment and 421.8 kg/ha in manure treatments).

Slightly higher share of medicinal plants was found at the Ilinac location (Tab. 3). It was highest in the plots without mineral fertilizer treatments and ranged from 18.0-64.3% (30.2%, on average). The dominant species are Anthyllis vulneraria, Genista sagittalis, Centaurea jacea and Thymus serpillum (Tab. 3). Anthyllis vulneraria (kidney-vetch), being an annual plant, appears periodically in grassland. In 1991 it almost did not appear (<1%) but in 1992 its share in the structure of grassland yield amounted to 60.2%. Due to increased contents of tannin, saponin and flavonoids, this plant possesses dermatological, diuretic and depurative effects. Its flower (Anthyllis flos) and an aboveground part at flowering stage are used (Anthyllis herba). In addition to its medicinal properties, this is a good quality plant that can be consumed by farm animals. Although control produced the lowest green mass yield (6.6 t/ha), due to a high share of medicinal plants (39.7%), it produced the highest plant mass yield (2620.2 kg/ha) of the said species, Anthyllis vulneraria accounting for 1993.2 kg/ha.

In other treatments the share of medicinal plants was lower and ranged from 7.1% (937.2 kg/ha) in continuous grazing to 15.3% (1866.6 kg/ha) in rotational grazing. In all treatments with mineral fertilizer application, the share of the species Anthyllis vulneraria was negligible (0.1-0.5%). The species Centaurea jacea had a considerably higher share, especially in rotational grazing (7.0% or 854.0 kg/ha), and in non-frequent (traditional) cutting (6.9% or 876.3 kg/ha). The share of other species was most frequently < 1%.

On the basis of the obtained results, we can conclude that:

Ass. Danthonietum calycinae abounds in medicinal plants. Floristic composition of the community includes 15-21 species possessing medicinal properties. Among the more prevailing species are Anthyllis vulneraria, Genista sagittalis, Centaurea jacea and Thymus serpillum, Achilea millefolium and Primula elatior.

The most widely distributed species in control plot is Anthyllis vulneraria. Being an annual plant, it appears periodically, so that one year it does not appear at all and the next year its share reaches more than 60%.

The application of NPK fertilizers decreased per cent of medicinal plants' share in the structure of grassland yield (3%), but the amount expressed in kg/ha was increased, concerning that total yield was increased (462.0 kg/ha). Quite contrary are findings in PK and manure treatments where relative share was 6% and 5.7%, respectively, and yield amounted to 444.0 and 421.8 kg/ha, respectively.

The interaction of NPK fertilizer with grassland utilization systems suppressed the species Anthyllis vulneraria, so that total share of all medicinal plants in all systems was lower than in control. The highest share of medicinal plants was found in rotational grazing (15.3% or 1866.6 kg/ha) and the lowest one in continuous grazing (7.1% or 937.2 kg/ha).

1. Lazarević D. (1991): Povećanje prinosa prirodnih travnjaka Kopaonika u uslovima intenzivne nege i iskorišćavanja. Magistarski rad. Polj. Fak. Zemun.

2. Mijatović M. and Pavešić-Popović J. (1972): Promena florističkog sastava prirodne livade tipa Agrostidetum vulgare uticajem mineralnih djubriva. agrohemija. 5-6. 225-238.

3. Mrfat-Vukelić S. (1987): Uticaj primene različitih doza mineralnih djubriva na promenu livadske vegetacije. Magistarski rad. Novi Sad.

4. Mrfat-Vukelić S. (1991): Uticaj mineralnih djubriva na sinekološke, ekofiziološke, i singenetske karakteristike livadskih zajednica Sjeničko- pešterske visoravni. Dok. disertacija. Novi Sad.

5. Stošić M., Mrfat-Vukelić S. and Kojić M. (1989): The influence of environmental and fertilizers on the yield and floristic composition of grasslands in Serbia. XVI International Grass. Congress. Vol.II. 1449-1453. Nice.