|Use of extensive set stocking of sheep for restoring original botanical diversity of the grassland in a mountain protected region
Research Institute of Animal Production
Prague 10 - Uhříněves, Czech Republic
The work was supported by the Grant Agency of the Czech Republic (Grant No. 507/94/1306 and No. 521/97/0499).
The Krkonoše National Park is a mountain region containing grasslands of a specific botanical composition. After the Second World War, the meadow management changed; interruption of agricultural activities changed the botanical composition. Experiments with employment of the set stocking for regeneration of the original biodiversity have been conducted recently. The system of extensive continual grazing of ewes with lambs seems to be advantageous for the grassland management in the mountains.
The aim of experimental observations was to examine the weight gains of sheep, grazing activity, influence of the meteorological factors and selective grazing behaviour during the season (preferencial grazing of different botanical species).
Experimental grazing was carried out at 1250 m above sea level using crossbreds of East Friesian and Stavropol Merino (from 1994 to 1996) and Kavkaz Merino (in 1997). Experimental grazing was performed on the electric-fenced pasture. The dominant plant species were: Polygonum bistorta, Deschampsia Cespitosa and other Poaceae sp. From mid-June to mid-September, 20 to 22 ewes with lambs were grazed at the stocking rate of four to five ewes per hectar. The behaviour of five to six marked ewes was recorded every ten minutes during daylight, for a total of 13 two-day observation periods. During these periods, the following values were recorded every hour: air temperature, solar radiation, relative air humidity and air velocity. Preferencial grazing of different botanical species was assessed every two weeks by examining the recent bite marks. The live weight of ewes and lambs was recorded at the beginning and at the end of an experimental period.
Average weight gains of lambs fluctuated from 166 to 192 g per head per day. The live weight of ewes increased during the experimental period by 2.9 to 7.5 kg per head on average. Ewes spent 502 minutes per day grazing; the grazing activity during daylight was divided into four to six periods. Ewes changed their grazing and resting patterns in response to the climatic variations. The meteorological factors were manifested mostly during extreme fluctuations. Grazing was reduced or ceased in response to intensive solar radiation, heavy rain, or wind speeds exceeding approx. 10 m . s -1 (depending on the terrain configuration). The optimum limits of the air temperature were between 5 and 20oC.
Individual plant species were grazed in this succession:
1. Poaceae sp. (Alopecurus pretensis, Agrostis sp., Holcus mollis and Al.);
2. Polygonum bistorta (dominant species);
3. Less palatable species (Deschampsia cespitosa, Rumex alpinus, Hypericum maculatum and moreover Calamagrostis villosa);
4. Returning to the newly grown Poaceae sp. and Polygonum bistorta.
A taste preference was recorded for Adenostyles alliariae, Ranunculus platanifolius, Silene vulgaris and the toxic Veratrum lobelianum, as well !
The experiments proved that it is possible to use an extensive set stocking of ewes with lambs to improve botanical diversity of the grasslands, even in the rough conditions present in Krkonoše National Park, 1250 m above sea level.