高寒草甸优势物种饲用品质对短期放牧的响应

为了解放牧强度对高寒草甸牧草饲用品质的影响,以青藏高原东北边缘高寒草甸为对象,研究了轻度(0.75牦牛单位·hm-2)、中度(1.00牦牛单位·hm-2)和重度(1.25牦牛单位·hm-2)放牧下优势植物珠芽蓼(Polygonum viviparum)和线叶嵩草(Kobresia capillifolia)的全氮、酸性洗涤纤维、中性洗涤纤维含量以及牧草的可吸收营养物质总量和相对饲喂价值等的变化。在放牧末期,中度放牧下牧草的植株高度显著高于其他放牧强度(P0.05)。在整个放牧期,中度放牧下牧草的全氮含量高于其他放牧强度,其中珠芽蓼的全氮含量在放牧末期显著高于重度放牧(P0.05);各放牧强度间植物的酸性和中性洗涤纤维含量在放牧末期无显著差异;中度放牧下牧草的营养价值指数整体呈上升趋势或保持稳定。在青藏高原东北边缘,3年的短期中度放牧利用有利于高寒草甸主要优势物种珠芽蓼和线叶嵩草保持较高而稳定的饲用品质。

Response of forage quality of the dominant species to short-term grazing in the alpine meadow at Qinghai-Tibetan Plateau

This study was aimed to understand the effect of grazing intensity on forage quality of the dominant species, Polygonum viviparum and Kobresia capillifolia, of the alpine meadow in the northeastern edge region of Qinghai-Tibetan Plateau. The changes in forage total nitrogen, acid detergent fiber, neutral detergent fiber, total digestible nutrients and relative feeding value were measured under light (0.75 cattle units·ha-1), moderate (1.00 cattle units·ha-1) and heavy (1.25 cattle units·ha-1) grazing intensities. At the end of grazing, plant height of the two dominant species under moderate grazing intensity was significantly higher than those under other intensities (P0.05). During the whole grazing, forage total nitrogen under moderate grazing was higher than those under other intensities, and it was significantly higher at the end of grazing than that under heavy grazing intensity for P.viviparum (P0.05). There was no significant difference in the contents of acid and neutral detergent fiber among different grazing intensities at the end of grazing. Nutritional value index showed a rising trend or kept stable under moderate grazing. Conclusively, the moderate grazing intensity was helpful to the dominant species, P.viviparum and K.capillifolia, in the alpine meadow at the northeastern edge of Qinghai-Tibetan Plateau to remain higher and stable forage quality.