摘要
分析退耕还林以来黄土高原气候的时间变化特征和空间分布特征,研究黄土高原局域气候变化的时空差异性及其与植被恢复的相关性,旨在探讨区域气候是否会对植被覆盖变化做出响应。使用GIS和统计学方法,基于黄土高原区1981年以来的气象数据和2000—2013年的MODIS/NDVI数据,使用趋势分析和Kriging插值,分析气候要素的时空变化特征,结合线性相关性,分析植被恢复和区域气候变化的关系。研究结果表明:1)近30年来黄土高原的气候变化总体趋势是气温上升,而其他气候要素无显著变化;退耕还林以后表现为降水增加、气温不再升高、风速降低、湿度减小。2)2000年以来,黄土高原最高气温变化率、最小相对湿度变化率空间特征表现为条带状,且与夏季NDVI变化率具有相似的空间分布特征。3)植被NDVI与1—4月份的最低气温正相关性显著,与7月份的最高气温负相关性显著,与5—9月份风速负相关性显著,与5月和7月的相对湿度正相关性显著。4)南温带植被NDVI与年均最大风速的负相关性显著,中温带植被NDVI与年均最小相对湿度的正相关性显著,还与春、秋季平均最小相对湿度的正相关性显著。总之,黄土高原的气候变化受到全球气候变化的影响,但是植被覆盖变化也是局地气候变化的1个因素,在温度、风速和湿度方面表现比较明显。
[Background]Vegetation coverage on the Loess Plateau has increased evidently attributing to the project of returning farmland to forest/grassland. Studies by climate modeling suggested that local climate would be impacted by land cover change. Further research is needed to make sure that weather evidence could be found in observed climate records and to explore the effect of vegetation restoration on regional climate. [Methods] The meteorological data from the Loess Plateau since 1981 and MODIS/NDVI data from 2000 to 2013 were analyzed by GIS and statistical methods. Mann-Kendall trend test and linear regression were used to analyze the time trend of climatic elements,and Kriging interpolation was used to analyze spatial variation of climate on the Loess Plateau with data from 130 meteorological stations; a linear regression was used to analyze increasing rate of NDVI. And Pearson linear correlation coefficient was used to indicate the correlation between climatic elements and NDVI. [Results] 1) Inthe past 30 years,air temperature increased significantly while no trends were found for other climate elements. Since the projects of returning farmland to forest,the precipitation increased while the wind speed and the relative humidity decreased significantly and air temperature did not keep the increasing trend. 2) Changing rates of the annual average maximum temperature and minimum relative humidity since 2000 showed a similar stripped distribution pattern as NDVI on the Loess Plateau. 3) NDVI had a positive correlation with minimum temperature from January to April and relative humidity in May and July but had a negative correlation with maximum temperature in July and with the wind speed from May to September. 4) In spatial distribution, although regional average relative humidity deceased significantly,approximately 30% of the region's minimum relative humidity showed an increasing trend.NDVI had a significant negative correlation with annual average maximum wind speed in the southern temperate zone and had a positive correlation with annual average minimum relative humidity in the midtemperate zone. [Conclusions]Climate on the Loess Plateau is influenced by the global climate change but vegetation restoration since the implement of returning farmland to forest/grassland had strong correlation with local climate,especially on the aspect of air temperature,wind speed and relative humidity.
引文
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