坡向对青藏高原高寒草地植被分布格局和牧草品质特征的影响

Effects of Slope Aspect on Vegetation Distribution Pattern and Forage Quality Characteristics of Alpine Grassland in the Qinghai-Tibet Plateau

为探究不同坡向草地植被构成和牧草品质特征,本研究对青藏高原东北缘不同坡向高寒草甸植被构成和牧草营养特征进行分析。结果表明:阴坡(Shady aspect,SHA)植物物种数和盖度显著高于阳坡(Sunny aspect,SUA)和山脊(Ridge,RI);SHA草地植物群落物种丰富度指数和多样性指数显著高于SUA和RI;禾本科、莎草科和可食杂类草地上生物量在SHA显著高于SUA和RI,不可食牧草地上生物量在RI显著高于SHA和SUA;植物中粗灰分(Crude ash,ASH)、粗脂肪(Ether extract,EE)、粗蛋白(Crude protein,CP)、钙含量(Calcium,Ca)、干物质消化率(Dry matter digestibility,DMD)、代谢能(Metabolic energy,ME)和可食牧草营养品质指数(Nutritional quality index,NQI)在SHA显著高于SUA,粗纤维(Crude fiber,CF)、中性洗涤纤维(Neutral detergent fiber,NDF)和酸性洗涤纤维(Acid detergent fiber,ADF)含量在SUA显著高于RI和SHA。建议在高寒草地的利用中,采用NQI评价草地营养价值,并考虑植物分布和营养品质在不同坡向的变化,实现精细化管理。

To clarify the effects of slope direction on plant community characteristics and forage nutritional quality,the vegetation composition and forage nutritional quality of alpine meadows with different slope directions on the northeast edge of Qinghai-Tibet Plateau were analyzed.The results showed that the number of plant species and vegetation coverage on the shady aspect was significantly higher than those on the sunny aspect and ridge.The species richness index and diversity index of plant communities on the shady aspect were significantly higher than those on the sunny aspect and ridges.The aboveground biomass of inedible herbage was significantly different among different slopes and showed the trend of RI>SHA>SUA.Among the edible forage groups,except leguminous grasses,Gramineae,Cyperaceae,and edible miscellaneous grasses showed significant differences in different slope directions,showing the trend of SHA>SUA>RI.The crude ash,crude fat,crude protein,dry matter digestibility,metabolic energy,and nutritional quality index of plants in the shady aspect were significantly higher than those in ridges and sunny aspect.The contents of crude fiber,neutral detergent fiber,and acid detergent fiber in the sunny aspect were significantly higher than those in ridges and shady aspect.Therefore,in the process of alpine meadow utilization,it is suggested to adopt a comprehensive index of forage nutrient quality to evaluate the grassland nutrient value quickly,and comprehensively consider the changes of plant community characteristics and nutrient quality in different slope directions,to realize fine management according to local conditions.