Effects of grazing domestic animals on litter layer and hydrological function of alpine shrubland in Eastern Qilian Mountains

This study aimed to provide a scientific basis for soil and water conservation in alpine shrub grasslands. The hydrological effects of grazing different livestock on the litter layer and soil layer of alpine shrub grassland were studied, including the moisture capacity, water holding rate, and interception amount of the litter layer and soil layer of grazing Gansu wapiti and mixed grazing yak and Tibetan sheep in the alpine shrubland in the Tianzhu alpine region of the eastern Qilian Mountains from July to August 2020. The result showed that the total litter thickness of the mixed grazing yak and Tibetan sheep plot (3.53 cm) was greater than the grazing Gansu wapiti plot (2.83 cm), and the total litter storage is expressed as the mixed yak Tibetan sheep plot (219.45 g·m⁻²) > the grazing Gansu wapiti plot (92.86 g·m⁻²) (P < 0.05); The average water holding capacity and initial water holding rate of litter in the mixed grazing yak and Tibetan sheep plot were higher than those in the grazing Gansu wapiti plot; the average maximum water holding capacity of litter is represented by the mixed grazing yak and Tibetan sheep plot (20.78 t∙ha⁻¹) > the grazing Gansu wapiti plot (10.71 t∙ha⁻¹), the average maximum water holding rate is represented by the mixed grazing yak and Tibetan sheep plot (221.00%) > the grazing Gansu wapiti plot (148.11%), and the average maximum interception is represented by the mixed grazing yak and Tibetan sheep plot (939.21 t∙ha⁻¹) > the grazing Gansu wapiti plot (348.58 t∙ha⁻¹), and the effective interception is shown as the mixed yak Tibetan Sheep plot (627.52 t∙ha⁻¹) > the grazing Gansu wapiti plot (187.90 t∙ha⁻¹) (P < 0.05). The soil moisture content of the shallow layer (0 – 40 cm) in the grazing Gansu wapiti plot between and under the shrubs were significantly higher than in the mixed grazing yak and Tibetan sheep plot, while the deep soil (40 – 100 cm) showed the opposite result; the bulk density of the 0 – 30 cm soil layer between shrub of the mixed grazing yak and Tibetan sheep plot > the grazing Gansu wapiti plot, the opposite of under shrub. The initial soil infiltration rate showed the grazing Gansu wapiti plot (10.98 mm∙min⁻¹) > the mixed grazing yak and Tibetan sheep plot (6.92 mm∙min⁻¹), and the steady infiltration rate also showed the grazing Gansu wapiti plot (7.12 mm∙min⁻¹) > the mixed grazing yak and Tibetan sheep plot (5.90 mm∙min⁻¹). To summarize; the mixed grazing of yak and Tibetan sheep is more conducive to water conservation and soil and water conservation in alpine shrubland.