Optimal Grazing Management Model On Stipa Krylovii Typical Steppe Ecosystem In Inner Mongolia

To seek for an optimal grazing management model of typical steppe, to discuss the grassland animal husbandry revolution and development, and to improve the farm incomes in this region, the condition of grassland, animal, farm income and climate data were used in this bioeconomic model (feeding balance model and farm systems model) of China to analyse public grazing system on Stipa krylovii typical steppe in Inner Mongolia. Connected the two models analysis with the different stocking rate control experiment data, the optimal grazing management model of Stipa krylovii typical steppe ecosystem was established here. The main research results are as follows:1. Simulations of the feed balance model indicated that there were big energy demand deficit from October to May at animal growth time, which is the reason for decreasing of animal live weight. Changing the lambing time to April, or feeding animal in the shed during winter and early spring will decrease the animal energy deficit.2. Solutions of the farm system model show that net income of mutton sheep, fine wool sheep and cashmere goats were all maximised at a stocking rate of around 2.275sheep/hm~2 and then falls substantially due to the influence of greater feeding costs at higher stocking rates. Net income from fine wool sheep system was slightly higher than the standard enterprise of mutton sheep up to a stocking rate of 3sheep/hm~2. Lambing in April or July will increase farm net return and decrease feeding cost. Greenhouse feeding will improve farm income of 9%, improve the lambing rate of 22% and wool yield of 10%.3. The current practice of high stocking rates (3sheep/hm~2) in Taipusi directly lead to poor grassland and low animal productivity and low farm incomes. Simulations of the bioeconomic model indicate that stocking rates of 1.55–2.275sheep/hm~2 provide the opportunity for grassland sustainable development and farm income improvement at the same time.4. Plant community coverage, height, aboveground biomass, net primary productivity and underground biomass were deceased with the increased stocking rate. Heavy stocking rate (3sheep/hm~2) decreased the dominance of perennial grasses, but increased the dominance of small half shrubs, forbs, annuals and biennials such as Artemisia frigida, Cleistogenes quarrosa, Potentilla acaulis, Convolvulus ammannii and Chenopodium glaucum. The diversity of plant community was highest when the stoking rate was 1.75sheep/hm~2, which is good for the stability and sustainable development of this ecosystem.5. With the stocking rate increased, soil water content, soil silt, soil organic matter, soil total nutrition, soil pH, soil bacteria quantity, azotobacter quantity and actinomycete quantity decreased, but soil bulk density, soil compaction, soil grit, soil fungi quantity increased. Soil respiration rate will decrease with the increased stocking rate and the grassland with 1.75sheep/hm~2 stocking rate has the highest soil respiration rate.6. The live weight of animal decreased with the increased stocking rate. Under highest stocking rate, the barren rate of pregnancy increased and lambing rate decreased. The birth weight and weight gain of lamb were decreased when the stocking rate was increased. There were negative correlations between body weight gain per sheep and grazing intensity, but body weight gain per hectare increased with the grazing intensity increased and then decreased at the highest.7. Changing the traditional grazing management for using greenhouse shed during winter and early spring will increase 3kg/sheep-5kg/sheep of ewe, 1.25kg/sheep-2.26kg/sheep of lamb.8. Combined with the analysis of bioeconomic model and different stocking rate results show that, the current optimal stocking rate of the typical steppe of Taipusi Banner is 1.75-2.275sheep/hm~2. The performance of decreasing stocking rate, changing the lambing time and penning animal in greenhouse during winter and early spring is the optimal grazing management model which can improve grassland productivity and farm income in Stipa krylovii typical steppe in Inner Mongolia.