Seasonal variations of main grassland types, hay yield, and nutritional value in Shaertao mountain, Xinjiang

The five main grassland types and the grass distribution of the Shaertao mountain in Zhaosu County were studied, and the hay yield and nutrient content were analyzed to reveal the seasonal variation in each grassland type. The aim was to identify the grassland type with the highest overall value and optimal utilization period. Five main grassland types were studied from May to July: Stipa capillata + Achnatherum splendens type (type Ⅰ), Iris ruthenica + Phleum phleoides type (type Ⅱ), Dactylis glomerata + herarum varianum type (type Ⅲ), Alchemilla sibirica + herarum varianum type (type Ⅳ), and Kobresia capillifolia + Carex stenocarpa type (type Ⅴ). The hay yield and nutrient content, including dry matter, crude protein, acid detergent fiber, neutral detergent fiber, ether extract, crude ash, calcium, phosphorus, and gross energy, were analyzed. A fuzzy similar priority ratio method, integrating nine indicators of hay yield and nutrient content, was used to evaluate the overall grassland values. The main conclusions are: 1) The highest overall value of the grassland type Ⅰ was observed in May, while the highest overall value for the other grassland types was observed in July. The lowest overall values for grassland types Ⅰ, Ⅱ, and Ⅲ during the period of observation were observed in November, and in August for the other grassland types (compared with July). 2) Grassland type Ⅲ exhibited the highest overall value during the study period from May to July. From August to November, grassland type Ⅱ exhibited the lowest overall value, followed by grassland type Ⅰ when the observations for October were included. The lowest overall value for grassland type Ⅴ was observed in August. The lowest overall values for grassland types Ⅰ and Ⅲ were observed in September and November. The results of this study provide a framework for the rational utilization of natural grassland resources.