内蒙古地区多时间尺度气候变化及草地叶面积动态响应研究

发布时间：2018-04-22 19:54

本文选题：气候变化 + 草地　；参考：《中国农业大学》2016年博士论文

【摘要】：内蒙古草地是北方重要的自然资源和天然的生态屏障。气候变化背景下,我国北方干旱半干旱区有暖干化的趋势,制约着草地生态系统的可持续发展。明确内蒙古地区近50年来气候资源空间分布和已经发生的变化特征,探索气候变化对草地生长的影响对将来气候变化背景下合理开发和保护内蒙古草地资源、有效发挥其生态屏障功能具有重要的意义。本文利用内蒙古地区历史气候数据分析了近50年来研究区气候要素的时空分布特征,同时利用遥感数据分析了近十几年内蒙古不同草地类型生育期叶面积指数的变化特征,结合气候栅格数据系统的分析了不同草地类型气候要素对草地生长的影响,探索了降水格局及其脉动特征对草地叶面积指数的持续影响,期望能够阐明干旱半干旱区草地生长对气候要素和降水脉动的响应特征和机理,为将来气候变化背景下内蒙古草地可能发生的变化提供科学依据和理论支持。主要结论如下：1、近50年来内蒙古地区在不断的变暖变干。1961-2012年间内蒙古地区呈显著增温趋势,增温速率超过全球平均增温速度的两倍。风速和日照时数均呈现显著下降的趋势,年降水量有轻微下降的趋势,湿润指数减少的趋势明显,表明近50年来研究区在不断的变暖变干。2月份研究区的平均温度增幅最大,最高、最低温度的增幅同样在2月份时达到最大值。2、研究区的参考作物蒸散对风速、温度、日照时数敏感系数为正值,对相对湿度敏感系数为负值,对温度的敏感系数最大,对日照时数的敏感性最低。温度和风速是影响研究区参考作物蒸散变化的重要的因素,由于研究区风速显著下降对参考作物蒸散的负贡献抵消了温度升高对参考作物蒸散增加的影响,使得研究区参考作物蒸散并无显著的增加或者降低的变化趋势。3、气候增暖使研究区草地生育期有提前的趋势。叶面积指数大于0.5时的初始日和终日都存在着前移趋势：温带禾草杂草类草原、温带丛生禾草草原、草甸和草本沼泽草原叶面积指数大于0.5时的初始日减少趋势分别为为1.5d/10a、4.6d/10a、1.8d/10a,终日前移趋势分别为3.8d/10a、 2.6d/10a、2.7d/10a。同时,叶面积指数达到最大值的日期也相应提前。4、草地叶面积指数与温度、降水量、日照时数之间具有极显著的线性关系。温带禾草杂草类草原的年降水量和生长季降水量大于其他两种类型草地,自然水分条件最好,草甸和草本沼泽类草原次之,温带丛生禾草草原最小。当月的降水量对生长季最大叶面积指数的形成有较大的影响,三种草地类型最大叶面积指数与当月降水量相关系数均比与上一月降水量相关系数大。温带丛生禾草草原对上一月的降水量有较明显的响应。5、研究区降水脉动均以小降水事件为主,大降水事件频率较低,且年际间变化幅度很大,但大降水事件对研究区草原年降水量贡献率较大。从长时间序列来看,10mm降水总量年际间变化均要明显大于5mm降水总量的年际变化,表明不同水文年份在大降水事件上的差异是其降水总量和降水格局差异的主要原因。6、温带禾草杂草类草原与草甸和草本沼泽草原最大叶面积指数的形成时前半个月的大降水事件对其影响较大。降水事件能够提高草地叶面积指数增长速率,促进草地的生长,温带丛生禾草草原最大叶面积指数增长率对8日降水量存在明显响应,大降水事件对后8天草地生长的影响较小。
[Abstract]:Inner Mongolia grassland is an important natural resource and natural ecological barrier in the north. Under the background of climate change, the arid and semi-arid areas in northern China have the trend of warming and drying, restricting the sustainable development of the grassland ecosystem. The spatial distribution of climate resources and the characteristics that have been changed in the last 50 years in Inner Mongolia area are clearly defined, and the climate change is explored. The influence of grassland growth is of great significance to the rational exploitation and protection of Inner Mongolia grassland resources in the future climate change and the effective use of its ecological barrier function. This paper analyses the temporal and spatial distribution characteristics of climate factors in the study area in the last 50 years by using historical climate data in Inner Mongolia area, and analyses nearly ten years by using remote sensing data. The change characteristics of the leaf area index of different grassland types in Inner Mongolia and the effects of different grassland types on the growth of grassland were analyzed by the climatic grid data system, and the continuous influence of the precipitation pattern and its pulsating characteristics on the grassland leaf area index was explored. The expectation could clarify the growth of grassland in arid and semi-arid areas. The response characteristics and mechanism of climate factors and precipitation pulsation provide scientific basis and theoretical support for the possible changes in Inner Mongolia grassland under the background of climate change. The main conclusions are as follows: 1, in the last 50 years, the Inner Mongolia region in Inner Mongolia region showed a significant warming trend during the continuous warming and dry.1961-2012 period in the last 50 years, and the temperature increasing rate was more than the whole. The average temperature of the ball increased two times. The wind speed and sunshine time showed a significant decline trend, the annual precipitation decreased slightly, the decreasing trend of the wetness index was obvious, indicating that the average temperature increase of the research area in the last 50 years was the largest, the highest, the lowest temperature increased in February. To the maximum value of.2, the reference crop evapotranspiration in the study area is positive for wind speed, temperature and sunshine hours, the sensitivity coefficient of relative humidity is negative, the sensitivity to temperature is the largest, and the sensitivity to sunshine time is the lowest. Temperature and wind speed are important factors affecting the change of crop evapotranspiration in the study area, because the wind speed in the study area is obvious. The negative contribution of descending to reference crop evapotranspiration offset the effect of temperature increase on the increase of reference crop evapotranspiration, making the study area reference crop evapotranspiration no significant increase or decreasing trend.3. Climate warming makes the grassland growth trend in advance in the study area. The initial day and the end of the leaf area index greater than 0.5 are all stored. The trend is: temperate grass grass grassland, temperate grasses grasslands, meadow and herbaceous swamp grassland leaf area index greater than 0.5 when the initial daily reduction trend is 1.5d/10a, 4.6d/10a, 1.8d/10a, respectively, 3.8d/10a, 2.6d/10a, 2.7d/10a., respectively, the leaf area index to the maximum value of the date is also phase There should be a very significant linear relationship between the grassland leaf area index and the temperature, the precipitation and the sunshine hours. The annual precipitation and the growth season precipitation of the temperate grass weed grassland are greater than those of the other two types of grassland. The natural water conditions are the best, the meadow and herbaceous marsh steppe are the second, and the temperate grasses grasslands are the smallest. In the same month, the grassland was the smallest. The precipitation has a great influence on the formation of the maximum leaf area index of the growing season. The correlation coefficient of the maximum leaf area index of the three grassland types and the monthly precipitation is larger than that of the previous month. The precipitation in the temperate grasses grassland has a significant response to the last month's precipitation, and the precipitation fluctuations in the study area are both small precipitation events. Major precipitation events have a low frequency and a large range of interannual variation, but large precipitation events have a great contribution to the annual precipitation of the grassland in the study area. From a long series of time series, the interannual variation of the total amount of 10mm precipitation is obviously larger than the annual variation of the total amount of 5mm precipitation, indicating that the difference in the precipitation events in different hydrological years is its precipitation. The main reasons for the difference of total and precipitation patterns are.6. The large precipitation events in the first half month of the grassland and meadow and meadow meadow and the grass swamp grassland have great influence on the difference. The precipitation event can increase the growth rate of the grassland leaf area index, promote the growth of grass land, and the largest leaf of the temperate grasses grassland. The area index growth rate has obvious response to the 8 day precipitation, and the impact of heavy precipitation on grassland growth is less after 8 days.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S812

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