Despite the essential role of micronutrients in plant metabolic processes and carbon cycle, the mechanisms by which micronutrients regulate plant community traits remain poorly understood. Here, we used a long-term experiment to explore the potential mechanisms of plant community micronutrients and traits along a precipitation gradient. Our results showed that plants shifted toward lateral growth and asexual reproduction over time. From 1985 to 2022, the plant community Fe content increased by 18.8% in the north but declined by 25.2% in the south of the typical steppe. Furthermore, plant community growth and reproduction were sensitive to both micronutrient contents and uptake efficiencies in the north of the typical steppe. While plant community Mn and Zn contents enhanced growth longitudinally, Zn and Fe uptake efficiencies hindered sexual reproduction. Furthermore, soil moisture and GDP per capita were the key drivers of micronutrient variation in the north and south of the typical steppe, respectively. Precipitation fluctuations primarily regulated community traits across all sites. In the arid site, micronutrient-driven shifts in reproduction stabilized the soil carbon stock by balancing biomass allocation. These findings can help us to better understand the coupling of plant micronutrients, traits, and soil carbon stocks, thereby providing the basis for a scientific grassland conservation strategy under global change scenarios.
Understanding livestock performance in typical steppe ecosystems is essential for optimizing grassland-livestock interactions and minimizing environmental impact. To assess the effects of different stocking rates on the growth performance, energy and nitrogen utilization, methane (CH4) emissions, and grazing behavior of Tan sheep, a 2-year grazing experiment in the typical steppe was conducted. The grazing area was divided into 9 paddocks, each 0.5 ha, with 3 spatial replicates for each stocking rate treatment (4, 8, and 13 sheep per paddock), corresponding to 2.7, 5.3, and 8.7 sheep ha–1. The results showed that the neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents of herbage varied between grazing years (P<0.05), with a positive correlation between stocking rate and crude fiber content in the herbage (P<0.05). Dry matter intake (DMI) decreased with increasing stocking rate (P<0.05), and the average daily gain (ADG) was highest at 2.7 sheep ha–1 (P<0.05). Compared to 2.7 and 8.7 sheep ha–1, the 5.3 sheep ha–1 treatment exhibited the lowest nutrient digestibility for dry matter, nitrogen, and ether extract (P<0.05). Fecal nitrogen was lowest at 8.7 sheep ha–1 (P<0.05), while retained nitrogen as a proportion of nitrogen intake was highest. Digestive energy (DE), metabolic energy (ME), and the ratios of DE to gross energy (GE) and ME to GE were highest at 8.7 sheep ha–1 (P<0.05). In contrast, CH4 emissions, CH4 per DMI, and CH4E as a proportion of GE were highest at 2.7 sheep ha–1 (P<0.05). Stocking rate and grazing year did not significantly affect rumen fermentation parameters, including volatile fatty acids, acetate, propionate, and the acetate/propionate ratio. At 8.7 sheep ha–1, daily grazing time and inter-individual distance increased, while time allocated to grazing, walking, and ruminating/resting decreased as stocking rates increased (P<0.05). This study highlights the importance of adjusting stocking rates based on the nutritional value of forage and grazing year to optimize grazing management.
Globally grassland ecosystems are facing unprecedented threats from continuous degradation and about 49% of grasslands are experiencing varying degrees of degradation. Resolving the imbalance between available forage and livestock demand is a major issue for grassland ecosystems. Transforming natural grasslands, which are on the brink of ecological collapse and have extremely high repair costs, into mowing grasslands can simultaneous address forage deficiency and also reduce the cost of long-distance transportation. Exploring the biomass yield and forage quality of multiple-mowing grasslands on the QTP is essential for calculating its construction scale. For this purpose, we conducted a grass-legumes cultivation experiment on the southeastern edge of the QTP and performed multiple mowing experiments. The results showed that compared to one-time harvesting during the growth period, multiple mowing significantly improved the biomass yield and nutritional quality of the grass, and gradually balanced towards quality as the mowing process progressed. Based on the experimental results, we used the current livestock loss rates in the QTP as a reference and further established different supplementary feeding modes from an energy supply perspective. Finally, we conclude that under the premise of no restriction on feeding, the artificial grassland needs to be increased to 2.22-9.38 times the current area. Under the restriction on feeding, the QTP needs to increase by 1.55-9.38 times, and the corresponding natural grassland area needs to be reduced by 3.96-16.75% and 2.77-16.75% respectively to meet the energy demand-supply. These results provide data support for grassland management planning in the QTP and inform the development of feasible strategies for improving the grass-livestock dynamics in the QTP.