Overload type and optimization of meadow carrying capacity in Maqin County in the Three-River Source Region, China

Abstract

Alpine meadows, comprising the main ecosystem of the Three-River Source Region, play an important role in the economic development of western pastoral areas. To determine whether the grazing level was too intense or the nutrient-carrying capacity of the meadows was overloaded, and to offer solutions in Maqin County, Qinghai Province, China, the meadows carrying capacity was determined by combining grass-yield and nutrients data for different seasons across different meadows. The results showed that the levels of crude protein (CP), ether extract (EE), ash, soluble sugars (SS), gas production, and energy value of forage in the summer–autumn grazing meadows were higher than those of the winter–spring meadows. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) of forage in the summer–autumn grazing meadows were lower than those of the winter–spring meadows. We found that no pastures were overloaded with metabolizable energy (ME) for the whole year but digestible crude protein (DCP) was overloaded in winter–spring. And there were differences in the amount carrying capacity (forage yield) of seasonal grazing meadows for the different herds, the overload types were annual overloading (herd A), overloaded in summer–autumn (herd B), overloaded in winter–spring (herd C), and not overloaded (herd D). Compared with the previous grazing mode, theoretical carrying capacity, DCP carrying capacity, and ME carrying capacity of herd A increased by 20, 19, and 27 sheep units, respectively, after optimization; herd B: 36, 31, and 45 sheep units, respectively; herd C: 28, 23, and 44 sheep units, respectively; and herd D: 43, 40, and 61 sheep units, respectively. In the Three-River Source Region and similar alpine pastoral areas, the grassland-livestock structure should be optimized to improve grassland vegetation status and increase the theoretical carrying capacity.