Analysis On Typical Grassland Types And Their Productivity Changes In Altay Mountain, Xinjiang

Altay region is located in the middle of the south of the Altay Mountains, which is in the northern end of the Xinjiang Uygur Autonomous Region. It is one of the national key pasturing areas, which is rich in grassland resources and types with large areas and concentrated distribution. Under the control of desert climate, Altay region is dominated by the desertification of grassland, and this grassland type becomes the base zone of Altay region. With the change in altitude of mountains, the distribution of grassland types shows the regularity of vertical zonality obviously. Altay region has grassland desert class, desert grassland class, mountain grassland class, mountain meadow grassland class, mountain meadow class, alpine grassland class, alpine meadow grassland class, and some intrazonal swamp class, lowland meadow grassland class. Grassland productivity is the basis of ecosystem productivity. It is an important index of grassland property and the main foundation to judge the ecosystem productivity. Therefore, it is of significance to grasp its dynamic changes.11 observation sample plots are set up on the grazing grasslands and typical grassland types are investigated in the paper, including 3 plain deserts, 3 mountain grasslands, 3 mountain meadows and 2 lowland meadows. The results show that: the grass coverage of plain deserts grassland was 30-52%, in which the highest yield of grasss is in July, next in June, and the yield of grasss in August is a little lower than in September. The grass coverage of lowland meadows grasslands is above 90%, in which the yield of grasss every month is high. The grass coverage of mountain grasslands is about 60%, in which the highest yield of grasss is in June, next in July. The grass coverage of mountain meadows grasslands is above 90%, in which the yield of grasss was high in June and July and decreasd in August and September for livestocks eating.Productivity changes of various types of grassland and its influence factors are analyzed in May-September from 2005 to 2009.The results show that: the growth of pasture reached the maximum in August 2006 and showed a decreasing trend in the corresponding months after 2007 both in grassland desert class and lowland meadow grassland class. The tendency of mountain meadow grassland class, mountain meadow class, mountain grassland class is consistent, which reached the maximum in August 2008 and decreased in the corresponding months after 2008. Besides, the grass yield in alpine grassland class was higher in August 2007, but it has little change in the corresponding months of the remaining years. Through analyzing, we find that: from the perspective of a single factor, the growing period of pasture has positive correlation with both temperature and precipitation. From the view on combination of temperature and precipitation, the higher average temperature, the more precipitation will have. Therefore, the growth of pasture will be faster.After the research, we find that the growth of seasonal pasture and various types of grasslands in Altay region presents a declining trend year by year in the case of over-grazing. Continuous drought in recent years has exacerbated the decline trend of grassland productivity. So, we should institute appropriate pasturing utilization to seasonal pasture and various types of grasslands as soon as possible. Besides, we also should implement the principle of limiting livestock according to the grass, harmonize grassland and livestock, in order to create a good basic condition for grassland's self-regeneration, to promote the improvement of grassland ecosystems and its productivity and to maintain the pasture plants (ecological) and livestock production (economic) double -objective optimization.