مقايسه تركيب پوشش گياهي مراتع تحت قرق، چراي آهو و گوسفند در پارك ملي گلستان و مناطق همجوار

Comparison of vegetation composition under exclosure, gazelle and sheep grazing in Golestan National Park and vicinities

To compare vegetation composition of rangelands under exclosure, gazelle grazing (Mirzabylou plain), moderate sheep grazing (Ghorkhoud Protected Area), and heavy sheep grazing (Spakhou village grazing unit), random plots of l-m2 were radiated from water points/ village along systematic transects were established and production based on life form of and canopy cover of different species were recorded. The results showed that in Mirzabylou plain with 440 kg/ha dry matters, production of shrubs and forbs increased as distance from water increased and gazelles usually preferred browsing shrubs. In Ghorkhoud protected area with 320 kg/ha dry matters, as moving from uplands to low lands near main road, forbs decreased and shrubs increased and there was not overgrazed as it was protected legally. The forbs did not completely destroyed and grasses had uniform distributions. In vicinity of Spakhou village, the range production is about 188 kg/ha dry matters and forbs and grasses overgrazed quite to the ground surface but shrubs are abundant. This range can carry 225 sheep and goat, but just now, the numbers of livestock are 5380 AU. The carrying capacity of Ghorkhoud rangeland is 457 AU which is equivalent to the permit issued by Range and Forest Organization. The number of gazelles is 184 which is quite below the carrying capacity of Mirzabylou range unit and could be increased to 650 gazelles. It can be concluded that wild ungulates like gazelles have little impact on vegetation, but high numbers of domestic livestock overgrazed the rangelands.