本文選題：NPP + CASA模型��； 參考：《重慶師范大學(xué)》2017年碩士論文

【摘要】：本研究采用了重慶市2000-2015年MODIS NDVI、氣溫、降水、太陽輻射、植被類型等月尺度數(shù)據(jù),并根據(jù)CASA模型反演得到了研究時段內(nèi)重慶市各月的植被凈初級生產(chǎn)力(NPP),通過統(tǒng)計分析、線性回歸、相關(guān)性分析等,對重慶市16年間植被NPP的時空變化規(guī)律及其植被NPP與主要?dú)夂蛞蜃娱g的響應(yīng)關(guān)系進(jìn)行了詳細(xì)研究分析。研究得出以下結(jié)論:1)2000-2015年這16年間,重慶市NPP年際變化規(guī)律主要表現(xiàn)為呈波動狀態(tài)緩慢上升趨勢,其植被NPP年均增加速率為0.7022/a。其中峰值出現(xiàn)在2003年、2008年,谷值出現(xiàn)在2001年、2006年、2009年。因此將16年間的植被NPP年際變化分為5個變化階段,包括兩個上升階段,分別為2001-2003年、2006-2008年;其次包括兩個下降階段,分別為2000-2001年、2003-2006年;2008-2015年為變化趨勢較穩(wěn)定階段。峰值出現(xiàn)的年份內(nèi)重慶市均未出現(xiàn)明顯的極端天氣,氣候條件良好,溫度、降雨量及其太陽輻射等氣候因子間分配比較均勻,恰好適宜植被的生長,從而使這些年份內(nèi)的NPP值達(dá)到比較高的水平。而谷值出現(xiàn)的年份主要受到夏季伏旱天氣的影響,從而使植被的光合作用效率降低,NPP值也由此降低,如2001年與2006年。2000-2015年間植被NPP隨季節(jié)變化的規(guī)律為,季節(jié)平均NPP由高到低分別是夏季(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)。同時,冬季與夏季NPP值呈現(xiàn)逐漸上升趨勢,其上升速率為1.01 g C/m2、0.0078 g C/m2,而春、秋季節(jié)均呈現(xiàn)出不同程度的下降趨勢,其下降速率分別為0.216 g C/m2、0.168 g C/m2。夏季NPP達(dá)到最高值,約占全年NPP值的43%。主要在于夏季的光、水、熱同期,達(dá)到植被的最佳生長條件,從而使植被在夏季的生產(chǎn)力達(dá)到最高。春季雨水充沛,且光照條件良好,其植被NPP僅次于夏季。秋冬季節(jié),重慶市地區(qū)多云霧,光照條件較差,其植被NPP值較低,尤其在冬季,NPP值僅為春季的1/3,夏季的1/4。2000-2015年植被NPP的月際變化規(guī)律為各月份NPP值變化呈拋物線變化,植被主要生產(chǎn)力集中在5月到9月,其NPP量約占全年NPP總量的65%。2)不同類型植被的NPP值存在較大的差異,其由高到低分別為闊葉林(804.35g C/m2)針闊混交林(719.07 g C/m2)針葉林(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)。影響植被NPP的原因除了氣候變化導(dǎo)致的NPP值降低或升高以外,不同植被類型由于其自身對環(huán)境的適應(yīng)能力的不同,如不同植被類型的葉面積大小不同,就會影響其吸收太陽有效輻射的效率,從而影響該類型植被NPP值。3)重慶市植被NPP的年際空間分異特征為,渝東北地區(qū)植被NPP總體較高,以城口、巫溪植被NPP為最高,因渝東北地區(qū)以山區(qū)為主,城市開發(fā)面積較小,森林覆蓋密度廣,人為干擾因素相對較少,且年均降水量豐富。其次,渝東南植被NPP值也保持較高水平,僅次于渝東北地區(qū),其中南川、潛江等區(qū)縣植被NPP均較高。而主城及周邊地區(qū)NPP總體偏低,是由于該區(qū)域工業(yè)、農(nóng)業(yè)較為發(fā)達(dá),城市建設(shè)面積較大,人為活動影響較大。在對不同季節(jié)植被NPP的分析過程中發(fā)現(xiàn),重慶市各季節(jié)植被NPP的空間分異規(guī)律與其年均NPP值的空間分異規(guī)律相一致,其主要由于重慶市整體范圍偏小,在其經(jīng)緯度覆蓋范圍內(nèi),氣候的變化對于重慶市內(nèi)部的局地氣候影響甚小。4)植被NPP與各氣候因子(氣溫、降水、太陽輻射)的年際相關(guān)關(guān)系為,在2000-2015年16年間,重慶市年平均溫度、年總降雨量及年太陽總輻射量均呈現(xiàn)出波動變化狀態(tài),其中,年均氣溫和年降水量呈現(xiàn)上升趨勢,而年太陽總輻射量呈下降趨勢,但其總體波動范圍均較小。年均氣溫保持在17-18℃范圍左右,年降水量維持在1100-1200mm范圍左右,年太陽總輻射值則保持在4000MJ/m2上下波動。各氣候因子的極值主要出現(xiàn)在2001年及2006年這種典型的極端天氣出現(xiàn)的年份里。重慶市植被NPP與氣溫、降水量、太陽輻射的相關(guān)性從大到小分別為:相關(guān)性(NPP-年降水量)相關(guān)性(NPP-年太陽總輻射)相關(guān)性(NPP-年均氣溫)。從年際變化規(guī)律上看,重慶市NPP與降水量、太陽輻射量之間呈正相關(guān)關(guān)系,而NPP與氣溫呈現(xiàn)負(fù)相關(guān)關(guān)系。NPP與年均氣溫、年降水量、年太陽總輻射的相關(guān)系數(shù)分別為0.2、0.5、0.05,因此降雨量對于植被NPP的影響較大,說明在植被生長過程中,水分充足尤為重要,而溫度的高低對于植被生長的影響則相對較小。5)從季節(jié)尺度分析植被NPP與各氣候要素間的相關(guān)關(guān)系,春季,重慶市植被NPP與氣溫、降水量呈正相關(guān)關(guān)系,而與太陽輻射值呈現(xiàn)負(fù)相關(guān)關(guān)系,春季氣溫開始回暖,促進(jìn)植被的生長,而隨著降雨量的增多,雨熱同期,從而使植被NPP快速升高;夏季,在16年間,平均溫度在25℃以上,個別年份達(dá)到30℃,夏天雨水充沛,其降雨量在243.66mm-655.13mm范圍內(nèi),太陽輻射量平均為1467.51 MJ/m2。植被NPP與氣溫、太陽輻射值呈負(fù)相關(guān)關(guān)系,NPP與溫度間的相關(guān)性較小,夏季氣溫對植被的生長狀態(tài)影響甚小,但太陽輻射值與NPP的相關(guān)性較大,而與降水量呈較顯著的正相關(guān)關(guān)系,此時植被NPP與降雨量、太陽輻射、氣溫之間的相關(guān)性依次減小;秋季,重慶市降雨量在193.99mm-408.25mm之間,其平均氣溫為18.37℃,溫度變化幅度較小,平均太陽輻射量為811.99 MJ/m2。重慶市秋季日照時數(shù)減少,而氣溫和太陽輻射是植被生長所必不可少的氣候條件,從而影響植被NPP,因此植被NPP與溫度、太陽輻射呈正相關(guān)關(guān)系,秋季由于雨水偏多,當(dāng)水分過量時也會影響植被的生長狀態(tài),因此,在秋季植被NPP與降水量呈負(fù)相關(guān)關(guān)系;冬季,重慶市平均氣溫為8.09℃,其波動范圍較小,冬季氣溫相對較高。重慶市冬季受云霧影響,日照時數(shù)非常少,其冬季平均太陽輻射量為619.75MJ/m2,其降雨量在37.97mm-86.84mm之間,其植被NPP與氣溫、太陽輻射呈現(xiàn)正相關(guān)關(guān)系,與降水量呈負(fù)相關(guān)關(guān)系。6)將本研究采用CASA模型所估算的NPP值與MOD17A3的NPP數(shù)據(jù)產(chǎn)品進(jìn)行簡單的相關(guān)性分析得出,結(jié)果表明本研究結(jié)果與其NPP產(chǎn)品相關(guān)性較高,因此從側(cè)面證明了本研究結(jié)果具有較高的可靠性。
[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.
【學(xué)位授予單位】：重慶師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：Q948.112

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