气候变化对三峡库区（重庆段）植被净初级生产力影响研究

发布时间：2018-06-28 12:26

本文选题：NPP + CASA模型　；参考：《重庆师范大学》2017年硕士论文

【摘要】：本研究采用了重庆市2000-2015年MODIS NDVI、气温、降水、太阳辐射、植被类型等月尺度数据,并根据CASA模型反演得到了研究时段内重庆市各月的植被净初级生产力(NPP),通过统计分析、线性回归、相关性分析等,对重庆市16年间植被NPP的时空变化规律及其植被NPP与主要气候因子间的响应关系进行了详细研究分析。研究得出以下结论:1)2000-2015年这16年间,重庆市NPP年际变化规律主要表现为呈波动状态缓慢上升趋势,其植被NPP年均增加速率为0.7022/a。其中峰值出现在2003年、2008年,谷值出现在2001年、2006年、2009年。因此将16年间的植被NPP年际变化分为5个变化阶段,包括两个上升阶段,分别为2001-2003年、2006-2008年;其次包括两个下降阶段,分别为2000-2001年、2003-2006年;2008-2015年为变化趋势较稳定阶段。峰值出现的年份内重庆市均未出现明显的极端天气,气候条件良好,温度、降雨量及其太阳辐射等气候因子间分配比较均匀,恰好适宜植被的生长,从而使这些年份内的NPP值达到比较高的水平。而谷值出现的年份主要受到夏季伏旱天气的影响,从而使植被的光合作用效率降低,NPP值也由此降低,如2001年与2006年。2000-2015年间植被NPP随季节变化的规律为,季节平均NPP由高到低分别是夏季(228.09 g C/m2)春季(133.72 g C/m2)秋季(117.33 g C/m2)冬季(51.94 g C/m2)。同时,冬季与夏季NPP值呈现逐渐上升趋势,其上升速率为1.01 g C/m2、0.0078 g C/m2,而春、秋季节均呈现出不同程度的下降趋势,其下降速率分别为0.216 g C/m2、0.168 g C/m2。夏季NPP达到最高值,约占全年NPP值的43%。主要在于夏季的光、水、热同期,达到植被的最佳生长条件,从而使植被在夏季的生产力达到最高。春季雨水充沛,且光照条件良好,其植被NPP仅次于夏季。秋冬季节,重庆市地区多云雾,光照条件较差,其植被NPP值较低,尤其在冬季,NPP值仅为春季的1/3,夏季的1/4。2000-2015年植被NPP的月际变化规律为各月份NPP值变化呈抛物线变化,植被主要生产力集中在5月到9月,其NPP量约占全年NPP总量的65%。2)不同类型植被的NPP值存在较大的差异,其由高到低分别为阔叶林(804.35g C/m2)针阔混交林(719.07 g C/m2)针叶林(650.26 g C/m2)灌木(544.37 g C/m2)草地(362.44 g C/m2)耕地(342.58 g C/m2)。影响植被NPP的原因除了气候变化导致的NPP值降低或升高以外,不同植被类型由于其自身对环境的适应能力的不同,如不同植被类型的叶面积大小不同,就会影响其吸收太阳有效辐射的效率,从而影响该类型植被NPP值。3)重庆市植被NPP的年际空间分异特征为,渝东北地区植被NPP总体较高,以城口、巫溪植被NPP为最高,因渝东北地区以山区为主,城市开发面积较小,森林覆盖密度广,人为干扰因素相对较少,且年均降水量丰富。其次,渝东南植被NPP值也保持较高水平,仅次于渝东北地区,其中南川、潜江等区县植被NPP均较高。而主城及周边地区NPP总体偏低,是由于该区域工业、农业较为发达,城市建设面积较大,人为活动影响较大。在对不同季节植被NPP的分析过程中发现,重庆市各季节植被NPP的空间分异规律与其年均NPP值的空间分异规律相一致,其主要由于重庆市整体范围偏小,在其经纬度覆盖范围内,气候的变化对于重庆市内部的局地气候影响甚小。4)植被NPP与各气候因子(气温、降水、太阳辐射)的年际相关关系为,在2000-2015年16年间,重庆市年平均温度、年总降雨量及年太阳总辐射量均呈现出波动变化状态,其中,年均气温和年降水量呈现上升趋势,而年太阳总辐射量呈下降趋势,但其总体波动范围均较小。年均气温保持在17-18℃范围左右,年降水量维持在1100-1200mm范围左右,年太阳总辐射值则保持在4000MJ/m2上下波动。各气候因子的极值主要出现在2001年及2006年这种典型的极端天气出现的年份里。重庆市植被NPP与气温、降水量、太阳辐射的相关性从大到小分别为:相关性(NPP-年降水量)相关性(NPP-年太阳总辐射)相关性(NPP-年均气温)。从年际变化规律上看,重庆市NPP与降水量、太阳辐射量之间呈正相关关系,而NPP与气温呈现负相关关系。NPP与年均气温、年降水量、年太阳总辐射的相关系数分别为0.2、0.5、0.05,因此降雨量对于植被NPP的影响较大,说明在植被生长过程中,水分充足尤为重要,而温度的高低对于植被生长的影响则相对较小。5)从季节尺度分析植被NPP与各气候要素间的相关关系,春季,重庆市植被NPP与气温、降水量呈正相关关系,而与太阳辐射值呈现负相关关系,春季气温开始回暖,促进植被的生长,而随着降雨量的增多,雨热同期,从而使植被NPP快速升高;夏季,在16年间,平均温度在25℃以上,个别年份达到30℃,夏天雨水充沛,其降雨量在243.66mm-655.13mm范围内,太阳辐射量平均为1467.51 MJ/m2。植被NPP与气温、太阳辐射值呈负相关关系,NPP与温度间的相关性较小,夏季气温对植被的生长状态影响甚小,但太阳辐射值与NPP的相关性较大,而与降水量呈较显著的正相关关系,此时植被NPP与降雨量、太阳辐射、气温之间的相关性依次减小;秋季,重庆市降雨量在193.99mm-408.25mm之间,其平均气温为18.37℃,温度变化幅度较小,平均太阳辐射量为811.99 MJ/m2。重庆市秋季日照时数减少,而气温和太阳辐射是植被生长所必不可少的气候条件,从而影响植被NPP,因此植被NPP与温度、太阳辐射呈正相关关系,秋季由于雨水偏多,当水分过量时也会影响植被的生长状态,因此,在秋季植被NPP与降水量呈负相关关系;冬季,重庆市平均气温为8.09℃,其波动范围较小,冬季气温相对较高。重庆市冬季受云雾影响,日照时数非常少,其冬季平均太阳辐射量为619.75MJ/m2,其降雨量在37.97mm-86.84mm之间,其植被NPP与气温、太阳辐射呈现正相关关系,与降水量呈负相关关系。6)将本研究采用CASA模型所估算的NPP值与MOD17A3的NPP数据产品进行简单的相关性分析得出,结果表明本研究结果与其NPP产品相关性较高,因此从侧面证明了本研究结果具有较高的可靠性。
[Abstract]:This study adopted monthly MODIS NDVI of 2000-2015 years in Chongqing, temperature, precipitation, solar radiation, vegetation type and other monthly scale data. According to the CASA model, the net primary productivity (NPP) of vegetation in each month of Chongqing in the period of study was retrieved. By statistical analysis, linear regression and correlation analysis, the spatio-temporal change of vegetation NPP in the city of Chongqing was changed in the last 16 years. The response relationship between NPP and the main climatic factors was studied in detail. The following conclusions were obtained: 1) in the 16 years of 2000-2015 years, the annual variation of NPP in Chongqing city showed a slow rising trend, and the annual increase rate of the vegetation NPP was 0.7022/a. in 2003 and 2008. The valley value appeared in 2001, 2006, 2009. Therefore, the interannual variation of vegetation NPP in 16 years was divided into 5 stages, including two ascending stages, 2001-2003 years and 2006-2008 years, followed by two descending stages, 2000-2001 years, 2003-2006 years respectively. The 2008-2015 year was in the stable stage. Peak years appeared in the year. There is no obvious extreme weather in Chongqing. The climate conditions are good, the temperature, rainfall and the solar radiation are evenly distributed, which is suitable for the growth of the vegetation, so that the NPP value in these years can reach a higher level. The year of the valley value is mainly influenced by the summer drought weather, thus the vegetation is vegetation. The efficiency of photosynthesis decreased and the NPP value decreased, for example, the seasonal variation of vegetation NPP in 2001 and.2000-2015 2006, the seasonal average NPP from high to low was in summer (228.09 g C/m2) spring (133.72 g C/m2) in autumn (117.33 g C/m2) winter (51.94 g C/m2), meanwhile, the winter and summer values showed a gradual upward trend. The rise rate was 1.01 g C/m2,0.0078 g C/m2, while spring and Autumn Festival showed a decreasing trend in varying degrees. The decline rate was 0.216 g C/m2,0.168 g C/m2. in summer NPP reached the highest value, and the 43%. of the NPP value of the year was mainly in the summer light, water and heat, reaching the best growth conditions of the vegetation, thus making the vegetation in summer. The productivity reached the highest. The spring rainwater was abundant and the light conditions were good, and the vegetation NPP was second only to the summer. In autumn and winter, the Chongqing area was cloudy and cloudy, the light conditions were poor and the NPP value of the vegetation was low. Especially in winter, the NPP value was only 1/3 in spring, and the monthly variation of NPP in the 1/4.2000-2015 year of 1/4.2000-2015 in summer was a parabolic change of the NPP value in each month. Line change, the main productivity of vegetation was concentrated from May to September, and its NPP amount was about 65%.2 of the total NPP of the year. The NPP values of different types of vegetation were greatly different, from high to low to broad leaved forest (804.35g C/m2) coniferous forest (719.07 g C/m2) coniferous forest (650.26 g C /m2) shrub (544.37 g) grassland (342.58) C/m2). In addition to the decrease or increase of the NPP value caused by climate change, the factors that affect the vegetation NPP have different vegetation types because of their own adaptability to the environment, such as the different leaf area of different vegetation types, which will affect the efficiency of absorbing solar effective radiation, thus affecting the vegetation NPP value.3 of the type of vegetation in Chongqing City, N The interannual spatial differentiation characteristic of PP is that the vegetation NPP in Northeast Chongqing is generally higher, and the Wuxi vegetation NPP is the highest in Chengkou, because of the mountainous area in the northeast of Chongqing, the urban development area is small, the forest cover density is wide, the human interference factor is relatively few, and the annual average precipitation is rich. Secondly, the NPP value of the East and the east of Chongqing is also kept high level, only a high level, only the second time. In the northeast of Chongqing, the vegetation NPP in Nanchuan, Qianjiang and other counties is high, but the overall NPP in the main city and the surrounding area is low. It is due to the industry in the region, the agriculture is more developed, the urban construction area is larger and the human activities are greatly influenced. In the analysis of the vegetation NPP in different seasons, the spatial differentiation rules of the vegetation NPP in each season of the city of Chongqing are found. The law is consistent with the spatial differentiation law of the annual NPP value, which is mainly due to the small overall scope of the Chongqing city. Within its latitude and longitude coverage, the climate change has a small impact on the local climate in Chongqing. The interannual correlation between the vegetation NPP and the climate factors (temperature, precipitation, solar radiation) is heavy in the 2000-2015 year and 16 years. The annual average temperature of the city, annual total rainfall and annual solar total radiation showed a fluctuation state, of which the annual average temperature and annual precipitation showed an upward trend, but the annual total solar radiation decreased, but the overall fluctuation range was smaller. The annual average temperature remained around 17-18 degrees C, and the annual precipitation remained at the range of 1100-1200mm. The total solar radiation value fluctuates up and down in 4000MJ/m2. The extreme value of each climate factor is mainly in the year of the typical extreme weather in 2001 and 2006. The correlation between the vegetation NPP of Chongqing and the temperature, precipitation, and solar radiation is the correlation (NPP- year precipitation) correlation (NPP- solar sun). The correlation of total radiation (total radiation) (NPP- annual temperature). From the interannual variation, there is a positive correlation between NPP and the amount of precipitation and solar radiation in Chongqing. The correlation between NPP and temperature has a negative correlation between.NPP and annual average temperature, annual precipitation, and the correlation coefficient of annual solar total radiation is 0.2,0.5,0.05, so the effect of rainfall on vegetation NPP is more than that. It shows that water adequacy is particularly important in the process of vegetation growth, and the influence of temperature on vegetation growth is relatively small.5). The correlation between vegetation NPP and climate factors is analyzed from seasonal scale. In spring, the vegetation NPP in Chongqing is positively related to the temperature and precipitation, but has a negative correlation with the solar radiation value. The seasonal temperature began to warm up and promote the growth of vegetation. With the increase of rainfall and the same period of rain and heat, the vegetation NPP increased rapidly. In summer, the average temperature was above 25 degrees centigrade in 16 years, the annual rainfall reached 30, the summer rainfall was abundant, the rainfall was within the range of 243.66mm-655.13mm, and the average solar radiation was 1467.51 MJ/m2. vegetation NPP and the average solar radiation. The temperature has a negative correlation with the solar radiation, and the correlation between NPP and temperature is small. In summer, the temperature has little influence on the growth of vegetation, but the correlation between the solar radiation value and the NPP is larger, and the correlation is more significant with the precipitation. At this time, the correlation between the vegetation NPP and the rainfall, the solar radiation and the temperature is decreasing in turn; autumn, The rainfall in Chongqing is between 193.99mm-408.25mm, the average temperature is 18.37, the temperature change is small, the average solar radiation is 811.99 MJ/m2. and the sunshine hours are reduced in the autumn of Chongqing. The temperature and the solar radiation are the necessary climatic conditions for vegetation growth, thus affecting the vegetation NPP, so the vegetation NPP and the temperature, solar radiation There is a positive correlation. In autumn, because of more rainfall and excessive water, the vegetation will also affect the growth state of vegetation. Therefore, in autumn, the vegetation NPP has a negative correlation with precipitation; in winter, the average temperature in Chongqing is 8.09, its fluctuation range is relatively small, and the winter temperature is relatively high. In winter in Chongqing, the number of sunshine hours is very little, its winter is very few, its winter is very small. Ji Pingjun's solar radiation is 619.75MJ/m2, its rainfall is between 37.97mm-86.84mm, its vegetation NPP is positively correlated with the temperature, solar radiation, and the precipitation is negatively correlated with.6). A simple correlation analysis between the NPP value estimated by CASA model and the NPP data of MOD17A3 is carried out in this study. The results show that this study is the result of this study. Results the correlation with NPP products is relatively high, so the results of this study show that the results are highly reliable.
【学位授予单位】：重庆师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948.112

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