Impacts Of Climate Change On Dominant Herbage Growth In Inner Mongolia Grassland

Effects of global climate change on grassland ecosystem have become a hot issue in domestic and foreign scientists. A lot of evidences indicate that the trend of climate warming and drying has brought the noticeable impact to the natural vegetation. Inner Mongolia grassland is one of the important grasslands in China. Where it is sensitive and fragile zone, grassland is degradated and the productivity of grassland is declining. Therefore, to explore the impact of climate change on the grass growth and development of Inner Mongolia grassland will help to improve the understanding of the potential of grassland resources. It plays an important role in the development of the local economy for the rational utilization and exploitation of grassland resources. The paper focused on the herbage growth in Inner Mongolia grasslands. The observation data were used from 81 meteorological station of 50 years, 8 animal husbandry meteorological station of 27 years, and 24 ecological station of 9 years(2004-2012). The impact of climate change on the herbage growth was analyzed by using contrast analysis and mathematical statistics method, and the preliminary conclusions are as follows:1. The climate change tends to increase temperature, and rainfall has not obviously decreased during 50 years in Inner Mongolia area. Climate trend showed that it becomes warmer strongly than its drier-warmer characteristics. The temperature has been increasing fast in time scale since 1990 s. During the herbage growing season, the temperature has been growing within a smaller range, and the rainfall increasing little in spring. The total of rainfall shows a larger decrease during June to August month。2. The climate change influences differently the growth period of the same herbage and growth period in different grassland types. Climate warming caused the herbage in meadow steppe turning green ahead of time, with wilting date postponed, and prolonged growing season. Typical steppe climate warming caused the herbage turning green.3. The growth height of different types of grassland and the same kind of grass response much differently to climate factors. And the Leymus chinensis grassland growth height negative correlation with the average temperature in summer, and growing season. While the positive correlation was showed in Typical Steppe of Leymus chinensis.4. The one of main reason is less rainfall with higher temperatures for herbage output poor. The spatial distribution of drier-warmer led to the distribution pattern of meadow steppe, typical steppe, desert steppe height. The effect of temperature to herbage outputs is positive in meadow steppe and typical steppe during the key period(late June to mid August). The climate yield rate varied between-82.8 kg/hm~2 and 51.9kg/hm~2, and-105.3 and 133.7kg/hm~2 accordingly with temperature increasing 1 ℃. The increase is-13.1～8.1kg/hm~2 and 4.6～20.8 kg/hm~2 accordingly with rainfall increasing 1mm.5. The precipitation is one of dominant factors in limiting the climate potential for forage production in Inner Mongolia. With significant regional differences, the overall distribution of climatic potential for forage production increases gradually from southwest to Northeast. These are respectively 4990～6175 kg/(hm~2·a), 4145～6070 kg/(hm~2·a), 3710～4975 kg/(hm~2·a) for meadow steppe, typical of the grassland and Desert Steppe. Utilization of climate resources of grassland is the low rate of production. These are respectively 20～60%, 30～70%, 60～80% for meadow steppe, typical of the grassland and Desert Steppe. It is showed in regression equation that the climate potential for forage production will increases 25～425 kg/(hm~2·a) with temperature increasing 1 ℃ and 1mm rainfall. At the typical grassland with low rainfall, it will decrease 10 ～55 kg/(hm~2·a). While it will increase 10～20 kg/(hm~2·a), 10～145 kg/(hm~2·a) in the typical grassland and Desert Steppe accordingly with high rainfall.