Ecological estimation of natural swards from the Central Northern region in Bulgaria

The efficiency and full utilization of natural resources, including natural grass associations, is essential for the development of plant and animal production. In the present study, an assessment was made of the productivity, stability and botanical composition of 8 natural swards in the region of Central Northern Bulgaria with a view to their effective use for the needs of animal husbandry. The variance analysis of the data shows a very high level of probability of the influence of the factor of grassland and the interaction of grassland × environment on the formation of yield. The most productive is sward 6, located in the area of Kateritsa - an average of 1004.21 kg ha-1 , and the excess compared to the average value for other grasslands is 54.8%. In terms of botanical composition, plant populations show significant variation - from 57 to 78% participation for cereal components and from 1 to 17% for legume components. The assessment of ecological stability carried out by the methods of regression, dispersion and non-parametric analysis determines different stability for grasslands, as these methods are based on different concepts of stability. GGE-biplot analysis, which allows for a comprehensive assessment of the studied grass associations in terms of their stability and productivity, identifies grassland 5 with location Lukovit as the closest to the ideal type, combining stability with relatively high productivity. Key words: productivity; stability; natural swards; esti