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1982-2013年新疆植被时空变化研究
许玉凤
学位类型博士
导师杨井 ; 陈亚宁
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业自然地理学
关键词遥感数据融合 Ndvi 长时间序列数据集 时空变化 新疆
摘要IPCC(2013)指出全球变暖是毋庸置疑的事实。植被对气候变化十分敏感。因此,研究植被时空变化及其对气候变化的响应,对全球变化背景下生态环境保护具有重要意义。 新疆地理位置特殊,气候变化显著,研究该地区植被变化对气候变化响应具有很强的代表性。本文首先利用逐像元一元线性回归模型来融合AVHRR/GIMMS与MODIS两种遥感数据,获得长时间序列NDVI数据集;然后结合气象数据插值图和土地覆盖类型图,采用相关分析、回归分析及GIS空间分析等方法,研究植被时空变化及其对气候变化的响应。通过分析植被现状及存在问题,和研究新疆植被时空变化规律及影响因子,提出相应的解决措施。 本文从以下几个方面对新疆植被时空变化进行研究: 1、研究区植被时空变化及其原因 近32年来,新疆植被NDVI变化呈显著的上升趋势。塔里木盆地西部和西北部、天山北坡等绿洲农业区,植被NDVI变化呈上升趋势;西北部山区和东南部农业区植被NDVI变化呈下降趋势。 气温上升幅度较大,植被NDVI与气温呈负相关的面积占植被覆盖面积比例48.10%;降水、潜在蒸散发有增加趋势,与降水量呈正相关的面积占71.85%,与潜在蒸散发呈负相关的面积占63.55%。 植被NDVI变化显著增加的原因主要是水分条件的改善、气温升高以及农作物需求量增加、农业的快速发展等原因所致;减少的原因主要与超载放牧、开矿、毁林毁草开荒等人类活动有关。 2、新疆农田、林地和草地植被时空变化研究 研究期间,农田植被呈显著上升趋势,草地上升趋势较小,林地有微弱下降趋势。 气温升高显著,与农田植被NDVI变化呈正相关的面积占农田植被覆盖面积的73.1%,而与林地和草地呈负相关的面积分别占55.0%和50.0%;降水波动性增加,与农、林、草变化呈正相关的面积分别占89.3%、79.2%和69.0%;农田和林地覆盖区潜在蒸散发呈微弱的下降趋势,而草地呈微弱的增加趋势,潜在蒸散发与植被NDVI变化呈负相关的面积分别占75.7%、55.5%和61.5%。 草地受气候变化的影响最大,其次是林地,农田植被受气候变化的影响最小。 水分条件是影响植被变化的重要因素,气温升高有利于农田植被生长,但气温升高过快或升高幅度较大会抑制林地和草地植被的生长。 3、北疆和南疆地区的平原和山地植被时空变化研究 (1)北疆平原地区: 植被NDVI变化呈显著上升趋势,其中农田植被上升趋势较大,林地和草地上升趋势相似。 农田植被NDVI与气温、降水呈正相关面积分别占北疆平原农田覆盖面积的70.0%和94.3%,且相关显著;与潜在蒸散发呈负相关的面积占82.5%,且负相关显著。 林地植被NDVI与气温呈负相关的面积占北疆平原林地覆盖面积的52.9%,且负相关显著;与降水呈正相关的面积占76.8%,且相关显著;与潜在蒸散发呈负相关面积占73.5%,且负相关显著。 草地植被NDVI与气温呈负相关面积占北疆平原草地覆盖面积的51.6%,且相关不显著;与降水量呈正相关的面积占88.5%,且相关显著;与潜在蒸散发呈负相关的面积占77.7%,且负相关显著。 研究结果表明,水分条件是植被NDVI变化的重要因素,气温对农田植被的作用大于林地植被和草地植被。 (2)北疆山地地区: 植被NDVI呈显著下降趋势,林地和草地下降趋势稍大于农田植被。 农田植被NDVI与气温呈负相关的面积占北疆山地农田植被覆盖面积的71.9%,且负相关显著;与降水呈正相关的面积占68.4%,且相关显著;与潜在蒸散发呈负相关面积占57.9%,且负相关不显著。 林地植被NDVI与气温呈负相关的面积占北疆山地林地覆盖面积的74.6%,且负相关显著;与降水呈正相关的面积占62.9%,且不显著;与潜在蒸散发呈负相关的面积逐年59.5%,且负相关不显著。 草地植被NDVI与气温呈负相关的面积占北疆山地草地覆盖面积的72.4%,且负相关显著;与降水呈正相关的面积占71.9%,且不显著;与潜在蒸散发呈负相关的面积占65.4%,且负相关显著。 研究结果表明,水分条件是植被NDVI变化的重要因素,气温升高不利于植被生长。气温升高、研究阶段后期降水的减少、火灾、鼠灾、病虫害以及平原地区的围栏保护导致放牧活动向山地转移等是植被呈下降趋势的重要原因。 (3)南疆平原地区: 植被NDVI变化呈显著增长趋势,其中农田植被上升趋势最大,林地次之,草地最低。 农田植被NDVI与气温、降水量呈正相关的面积分别占南疆平原农田植被覆盖面积的80.5%和86.4%,且相关显著;与潜在蒸散发呈负相关的面积占70.8%,且负相关不显著。 林地植被NDVI与气温、降水量呈正相关的面积分别占南疆平原林地植被覆盖面积的57.1%和73.1%,且相关显著;与潜在蒸散发呈负相关的面积占50.0%,且不显著相关。 草地植被NDVI与气温、降水量呈正相关面积占46.2%和56.3%,且相关显著;与潜在蒸散发呈负相关面积占51.4%,且相关不显著。 研究结果表明,气温、降水的增加有利于植被生长。气温和潜在蒸散发对草地影响程度较大,对农田植被影响最小。农田防护林面积和农业灌溉面积的增大、农业技术的提高对南疆平原地区植被生长有重要的促进作用。 (4)南疆山地地区: 植被NDVI呈上升趋势,农田植被上升趋势最大,林地次之,草地稍低。 农田植被NDVI与气温呈负相关的面积占南疆山地农田植被覆盖面积的60.5%,且正相关不显著;与降水量呈正相关的面积占87.5%,且相关显著;与潜在蒸散发呈负相关面积占52.5%,且相关不显著。 林地植被NDVI与气温呈正相关面积占南疆山地林地植被覆盖面积的73.2%,且相关不显著;与降水量呈正相关面积占97.6%,且相关显著;与潜在蒸散发呈负相关面积占75.6%,且负相关显著。 草地植被NDVI与气温呈负相关的面积占南疆山地草地植被覆盖面积的50.5%,且不显著;与降水量呈正相关的面积占66.7%,且相关显著;与潜在蒸散发呈负相关的面积占58.5%,且负相关显著。 研究结果表明,水分条件对植被生长作用较大。气温的影响程度大于降水,且最低气温的影响程度较大。 综合来看,水分条件是新疆植被生长的重要条件,气温升高有利于农田植被、平原草地、和南疆林地植被的生长,不利于山地植被、北疆林地植被的生长。 总之,水分条件是影响新疆植被生长的重要因素,近十几年气温升高的负效应在呈现,人类活动的影响程度在不断加大。 论文最后指出研究中存在的不足之处及今后需要进一步深入研究的问题。; IPCC (2013) states that “Warming of the climate system is unequivocal”. Vegetation is sensitive to climate change. It is of great significance to study the spatio-temporal variation of vegetation and its response to climate change in order to protect the ecological environment from global change. Xinjiang lies in Northeast of China, and its peculiar climate and geological characteristics make it an worthwhile place to study vegetation change in response to climate change. This thesis firstly used a linear regression model to fusion GIMMS/AVHRR and MODIS remote sensing data to obtain a long time series of NDVI dataset, and then studied the spatio-temporal change of vegetation and its response to climate change with meteorological data interpolation and land cover type map, by using correlation analysis, regression analysis and GIS spatial analysis method. This thesis studied the spatio-temporal change of vegetation in Xinjiang to understand the current situation and the existing problems of vegetation cover, and try to find the solution to these problems. The whole study on the spatio-temporal change of vegetation in Xinjiang can be divided into the following several aspects: 1. The spatio-temporal change of vegetation cover and causes in Xinjiang There is significant increasing trend in Xinjiang in the past 32 years. There is an increasing trend of oasis agricultural vegetation in the western and northwestern of Tarim Basin and in the north slope of Tianshan Mountains, while there is a decrease trend of vegetation change in northwest mountains and in the southeast agricultural area. The temperature rises significantly, and the negative correlation between the vegetation NDVI and temperature account for 48.10% area of vegetation cover. Precipitation and potential evaporation have an increasing trend, and the positive correlation between the vegetation NDVI and precipitation accounts for 71.85% area of vegetation cover, and its negative correlation with potential evaporation is 63.55% area of vegetation cover. The significant increase trend of vegetation cover is mainly due to the improvement of water condition, temperature rise, crop demand increase, the quickly improvement of agriculture etc.; while the main reasons for the decreasing trend are overgrazing, mining, deforestation, destroyed grassland and other human activities. 2. Spatio-temporal vegetation change of cropland, forestland and grassland in Xinjiang The increasing trend of cropland is significantly while the increasing trend in grassland is not significant, and there is a slightly decrease trend in forestland during the study period. Temperature rises significantly, and the area of positive correlation between vegetation NDVI change and temperature accounts for 73.1% area in cropland, while the negative correlation in the forestland and grassland accounts for 55.0% and 50.0% area respectively. Precipitation increased volatility, and the area with positive correlation between precipitation and cropland, forestland and grassland account for 89.3%, 79.2%, and 69.0% area respectively. There is a slightly decreasing trend of potential evaporation in cropland and forestland, while there is a slightly increase trend in grassland. The area of negative correlation between potential evaporation and cropland, forestland and grassland account for 75.7%, 55.5% and 61.51% area, respectively. The influence of climate change on the grassland is the largest, followed by forestland, the least influence is on cropland. Water condition is the important factors influencing vegetation changes. The temperature rise is beneficial to cropland vegetation growth, but quick or large temperature rises will restrain the growth of the forestland and grassland. 3. The spatio-temporal change of vegetation cover and causes in plains and mountains in northern Xinjiang and southern Xinjiang (1) In the plains of northern Xinjiang: The vegetation NDVI is in a significantly increasing trend. The increasing trend of cropland is larger than that of forestland and grassland, and the trends of forestland and grassland are similar. In cropland: Positive correlations between the temperature, precipitation and vegetation NDVI account for 70.0% and 94.3% area respectively with a significant relationship, while negative correlation between vegetation NDVI and potential evaporation account for 82.5% area with a significant negative relationship. In forestland: The negative correlation between vegetation NDVI and temperature account for 52.9% area with a significant negative relationship. The positive correlation between vegetation NDVI and precipitation account for 76.8% area with a significant relationship. The negative correlation between vegetation NDVI and potential evaporation account for 73.5% area with a significant negative relationship. In grassland: The negative correlation between vegetation NDVI and temperature account for 51.6% area without significant relationship. The positive correlation between vegetation NDVI and precipitation accounts for 88.5% area with a significant relationship. The negative correlation between vegetation NDVI and potential evaporation accounts for 77.7% area with a significant negative relationship. The results show that water condition is the important factor on the changes of vegetation NDVI, and the effect of temperature in cropland is greater than that in forestland and grassland. (2) In the mountains of northern Xinjiang: The vegetation NDVI is in a significant decrease trend, and the trends in forestland and grassland are slightly greater than that in the cropland. In cropland: The negative correlation between vegetation NDVI and temperature accounts for 71.9% area with a significant negative relationship. The positive correlation between vegetation NDVI and precipitation accounts for 68.4% area with a significant relationship, and the negative correlation between vegetation NDVI and potential evaporation accounts for 57.9% area with no significant negative correlation. In forestland: The negative correlation between vegetation NDVI and temperature accounts for 74.6% area with a significant negative correlation, the positive correlation between vegetation NDVI and precipitation accounts for 62.9% area with no significant relationship, and the negative correlation between vegetation NDVI and potential evaporation accounts for 59.5% area with no significant negative relationship. In grassland: The negative correlation between vegetation NDVI and temperature accounts for 72.4% area with a significant negative relationship, the positive correlation between vegetation NDVI and precipitation accounts for 71.9% area with no significant, and the negative correlation between vegetation NDVI and potential evaporation accounts for 65.4% area with a significant negative relationship. The results show that water condition is the important factor on the changes of vegetation NDVI, while temperature rise has a negative impact on vegetation growth. The causes for the decrease trend of vegetation change are: the temperature rise, the precipitation decline in the late research phase, fire hazard, the diseases and insect pests of plant, mice disaster, and the fence protection measures of grassland in plains made the grazing shift to mountains. (3) In the plains of southern Xinjiang: The vegetation NDVI change shows a significant increasing trend. It is the largest in cropland, then in forestland, and the smallest in grassland. In cropland: The positive correlation between vegetation NDVI and temperature, precipitation account for 80.5% and 86.4% area respectively with a significant relationship, while the negative correlation between vegetation and potential evaporation accounts for 70.8% area without significant negative relationship. In forestland: The positive correlation between vegetation NDVI and temperature, precipitation account for 57.1% and 73.1% area respectively with a significant relationship, while the negative correlation between vegetation NDVI potential evaporation accounts for 50.0% area without significant relationship. In grassland: The positive correlation between vegetation NDVI and temperature, precipitation account for 46.2% and 56.3% area respectively with a significant relationship, while the negative correlation between vegetation and potential evaporation accounts for 51.4% area without significant relationship. The increase of temperature and precipitation is beneficial to vegetation growth. The effect of temperature and potential evaporation on the grassland is bigger than that on cropland and forestland, and the least is on cropland. The enlargement area of forestland to protect cropland, the agricultural irrigation area increasing, and the improvement of agricultural technology have an important role in promoting vegetation growth. (4) In the mountains of southern Xinjiang: There is an increasing trend of vegetation NDVI. The trend is the largest in cropland, then the forestland, and grassland. In cropland: The negative correlation between vegetation NDVI and temperature accounts for 60.5% area without significant relationship. The positive correlation between vegetation NDVI and precipitation accounts for 87.5% area with a significant relationship. The negative correlation between vegetation NDVI and potential evaporation accounts for 52.5% area without significant relationship. In forestland: The positive correlation between vegetation NDVI and temperature accounts for 73.2% area without significant relationship. The positive correlation between vegetation NDVI and precipitation accounts for 97.6% area with a significant relationship. The negative correlation between vegetation NDVI and potential evaporation accounts for 75.6% area with a significant negative relationship. In grassland: The negative correlation between vegetation NDVI and temperature accounts for 50.5% area without significant relationship. The positive correlation between vegetation NDVI and precipitation accounts for 66.7% area with a significant relationship. The negative correlation between vegetation NDVI and potential evaporation accounts for 58.5% area with a significant negative relationship. Water condition plays an important role on vegetation growth. The influence of temperature on vegetation cover is greater than that on the precipitation, and the influence of the minimum temperature is larger than other factors. In generally, water condition is important to vegetation growth in Xinjiang. The temperature increase is good for the growth of cropland, the grassland in plains and the forestland in southern Xinjiang; while it is suitable to the growth of vegetation in mountains and forestland in northern Xinjiang. To sum up, water condition is the important factor that affects growth of vegetation in Xinjiang; there is an negative effect of temperature rise in recent decade; the influence of human activity is increasing. In the end, this thesis also lists out the limitations of the research, and some questions which should be addressed in the future.
学科领域自然地理学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14629
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
许玉凤. 1982-2013年新疆植被时空变化研究[D]. 北京. 中国科学院大学,2015.
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