Condition and changes in types of natural pasture swards in the Sakar mountain under the influence of climatic and geographic factors

V. Vateva, K Stoеva, D. Pavlov
Abstract. The research focuses on the vegetative development, the state and changes of the types of natural pasture compositions from the Sakar mountains region, by tracking the influence of the climatographic factors. The favorable combination of climatic indicators and the good water ensure the normal vegetative development of the natural pasture compositions and grassland, and in the different kinds of pastures their height varies from 40 to 71 cm. The unfavorable manifestation of the climatographic conditions negatively affects the vegetative development of the pasture compositions. It changes the composition and ways of usage, and the height reduces by 15 to 32 cm. The most significant changes are observed in pasture-type Andropogon ischaemum, in which the height decreases by 32 cm, and the composition of the pasture grassland considerably degrades. Weaker affected by the changes in the climatic parameters are the pastures type Cynodon dactylon – Lolium perenne and Festuca myuros – Bromus sp., due to the larger percentage of drought-resistant species, which constitute them. Water supply in the months April, May and June exercises stronger influence on the grass height than the rainfall amount during the entire vegetation period.