城市化过程广州土地覆盖变化对净初级生产力格局的影响

发布时间：2018-05-29 00:21

本文选题：广州 + 净初级生产力　；参考：《中山大学》2016年博士论文

【摘要】：随着经济、人口的发展,城市化在中国乃至全世界迅速蔓延,城市化过程中所伴生的环境问题从城市、区域乃至全球尺度都影响着地球表层的自然现象和生态过程,并导致土地利用/土地覆盖(Land use and land cover,LULC)发生重大变化,从而直接影响植被净初级生产力(Net primary productivity,NPP)。研究城市扩张、土地覆盖变化及其对NPP的影响,可以更好地了解城市生态系统结构和功能的变化对社会自然环境变化的反馈作用。本研究以华南地区最大的城市—广州作为研究地,首先分析了1979-2013年广州城市化过程的特征及LULC变化,并基于CASA(Carnegie Ames Stanford Approach)模型估算了广州市2001-2013年逐月NPP,分析了2001-2013年广州市NPP年际、季节的时空格局变化,进一步探讨了13年来城市化过程中土地覆盖变化和气候变化对NPP的影响。主要研究结果如下:(1)城市大面积扩张,导致土地覆盖显著变化。1979-2013年,广州建成区面积共增加了1512.24 km2,年均增长率为11.3%,城市扩张经历了四个不同阶段:低速发展(1979-1990)、快速发展(1990-2001)、高速发展(2001-2009)及稳定发展(2009-2013)。城市扩张导致土地格局发生重大变化,耕地被严重破坏,35年间减少了1746.06 km2,约有769.46 km2的耕地转化为建设用地;林地和农田森林过渡带面积大幅度减少;城市景观趋于破碎化。(2)2001-2013年,在时间尺度上,广州及其5片区NPP呈现减少趋势。13年中,整个研究区NPP年变化趋势为-8.57 NPP g C/m2,共减少0.38 Tg C。5片区中,中心片区NPP年均值最低(292.06 g C/m2),东北片区最高(1067.31g C/m2),中心、南部和北部片区NPP在研究期内呈现极显著减少趋势(p0.01)。NPP在空间分布上存在明显差异,且年际变化明显。在不同方向样带中,中-北样带NPP均值最高为431.76 g C/m2,中-南样带最低为337.53 g C/m2,样方NPP值从东、南和北向中心均呈现显著减少趋势。除2005-2009时段,其他时段内大部分区域NPP均呈减少状态。在像元尺度上,中心、北部和南部片区NPP距平变异程度较大,根据NPP像元斜率变化,北部片区NPP减少趋势最为明显,平均值达到-14.98%,其次为南部片区(-8.44%);NPP减少显著和极显著的区域约有28.3%集中在北部片区,NPP增加显著和极显著区域则集中在以林地为主的东北片区。(3)研究期内不同季节和不同植被的NPP均存在显著差异。NPP最高值出现在夏季(454.39 g C/m2),最低值出现在冬季(54.08 g C/m2)。13年中NPP在夏季减少最明显,年变化趋势为-4.18 g C/m2,冬季最不明显为-0.99 g C/m2;在像元尺度上,四个季节的NPP均呈现减少趋势,且减少不显著(p0.05)的面积比例最高。在不同植被类型中,常绿阔叶林的NPP均值最高(1327.22 g C/m2),灌丛的最低(483.08 g C/m2),且不同土地覆盖类型的NPP值在东北片区最高,在中心片区最低。(4)城市化过程对NPP产生显著影响。利用距城市中心点不同距离的缓冲区法进行分析,5 km范围内的NPP均值最低(179.41 g C/m2),70 km范围内的最高(1225.87 g C/m2),且随着距城市中心距离的增大,不同距离缓冲区内NPP均值呈现极显著增大(p0.001)趋势。人类活动范围和强度与NPP呈现显著负相关;10-40 km缓冲区范围内人类活动强度在13年内增加了0.1802,导致NPP减少最明显;不同土地覆盖类型的NPP均值和在5 km范围内最低,在40 km的范围内最高,但在10-40 km缓冲区内减少最明显。(5)土地覆盖变化导致NPP发生重大变化。在土地相互转换过程中,不同土地类型的转出和转入对NPP变化产生显著影响,除2005-2009时段外,其他时段内的土地转换均导致NPP总量减少。通过对2001耕地和2013建筑用地基准范围、NPP减少显著和极显著范围内的土地覆盖和NPP变化的分析,发现城市的大范围扩张及耕地的大幅度缩减是导致三个范围内NPP均值显著减少的主要原因。土地利用和土地覆盖变化导致的NPP损失(NPPlulc)在空间上存在明显差异。研究期间,中心片区NPPlulc均值最高达到1353.05 g C/m2,其次为南部片区为1248.21 g C/m2,东北片区最低为521.83 g C/m2。在空间变化上,不同方向样带由于城市开发及土地覆盖变化强度不同,导致NPPlulc差异明显,且样方NPPlulc在中心向东、南、北的不同方向上均呈极显著减少趋势(p0.01)。(6)气候变化显著影响NPP变化。不同年份、不同季节、不同月份和不同覆盖类型的NPP与温度、太阳辐射均呈正相关,与降水呈负相关。综合三个气候因子对NPP的影响,研究区内大部分区域NPP的变化主要由温度和太阳辐射控制,而降水往往成为NPP积累的限制因子。地形因素极大影响林地NPP的变化,海拔对林地NPP的影响远大于坡度和坡向对林地NPP的影响。(7)气候和土地覆盖变化对NPP的影响量和影响率均存在明显差异。研究期内,在时间尺度上,由于气候和土地覆盖变化导致NPP分别减少了0.2892 T g C和0.4239 T g C。林地尤其是常绿阔叶林对气候变化敏感,而受人类活动影响较大的土地类型,如耕地、农田森林过渡带和城市绿地(草地、灌草和木本草地)等,其NPP总量变化主要受土地覆盖变化的影响。在空间尺度上,东北片区NPP多受气候变化影响,北部、东部和南部片区NPP多受土地覆盖变化影响,中心片区中部区域NPP则多受两者交叉影响。
[Abstract]:With the development of economy and population, urbanization is spreading rapidly in China and the whole world. The associated environmental problems in the process of urbanization affect the natural phenomena and ecological processes of the earth's surface from cities, regions and even global scales, and lead to significant changes in land use / land cover (Land use and land cover, LULC). Net primary productivity (NPP). The study of urban expansion, land cover change and its impact on NPP can better understand the feedback effect of urban ecosystem structure and function changes on social and natural environment changes. This study takes the largest city in Southern China as the research site, first of all. The characteristics and LULC changes of the urbanization process in Guangzhou in the past 1979-2013 years are analyzed. Based on the CASA (Carnegie Ames Stanford Approach) model, the month by month NPP of Guangzhou city is estimated. The temporal and spatial pattern changes of Guangzhou city NPP year and season are analyzed. The change of land cover and climate change in the course of urbanization in the past 13 years is further discussed. The main research results are as follows: (1) the large area expansion of the city led to a significant change in land cover for.1979-2013 years, the area of Guangzhou built-up area increased by 1512.24 km2, the average annual growth rate was 11.3%, and the urban expansion experienced four different stages: low speed development (1979-1990), rapid development (1990-2001), high-speed development (2001-2009) and stability. Development (2009-2013). Urban expansion resulted in significant changes in the land pattern, severely damaged cultivated land, reduced by 1746.06 km2 in 35 years, about 769.46 km2 of cultivated land converted into constructive land; the area of forest and farmland forest transition zone decreased greatly; the urban landscape tended to break down. (2) 2001-2013 years, Guangzhou and 5 tablets on the time scale. The decrease trend of area NPP is.13 year, and the change trend of NPP year in the whole study area is -8.57 NPP g C/m2, which reduces the 0.38 Tg C.5 region, the mean value of the central region is the lowest (292.06 g C/m2), the northeast region is the highest, and the center, the South and the northern region show a very significant decreasing trend in the study period. There are obvious differences, and the interannual variation is obvious. In the different direction samples, the NPP mean of middle to North sample belt is 431.76 g C/m2, the Middle South sample is 337.53 g C/m2, and the NPP value of the sample square shows a significant decreasing trend from the East, the South and the north to the center. Except for the 2005-2009 period, the NPP in most regions is reduced. In the central, central, northern and southern regions, the NPP anomaly has a greater degree of variation. According to the variation of the slope of NPP pixel, the trend of NPP reduction in the northern region is the most obvious, the average value reaches -14.98%, the next is the southern region (-8.44%), and the significant and extremely significant regions of the NPP decrease about 28.3% in the northern region. NPP increases significantly and the extremely significant regions are concentrated in the region. (3) there was a significant difference in NPP between different seasons and different vegetation in the study period. The highest value of.NPP appeared in summer (454.39 g C/m2). The lowest value appeared in winter (54.08 g C/m2) and NPP decreased most obviously in summer, and the annual variation trend was -4.18 g C/m2. The NPP of the four seasons showed a decreasing trend, and the area ratio of P0.05 was the highest. In the different vegetation types, the average NPP of evergreen broad-leaved forest was the highest (1327.22 g C/m2), the lowest (483.08 g C/m2), and the NPP value of different land cover types was the highest in the northeast area and the lowest in the central area. (4) the urbanization process to NPP The NPP mean in the range of 5 km is the lowest (179.41 g C/m2) and the highest (1225.87 g C/m2) within the range of 70 km, and with the increase of distance from the city center, the mean NPP mean in different distance buffers shows a very significant increase (p0.001) trend. Human activity range. And intensity and NPP showed significant negative correlation; 10-40 km buffer zone within the range of human activity increased by 0.1802 in 13 years, leading to the most obvious decrease in NPP; the NPP mean of different land cover types and the lowest in the 5 km range, the highest in the 40 km range, but the most obvious decrease in the 10-40 km buffer zone. (5) land cover change led to NPP hair In the process of land conversion, the transfer and transfer of different land types have a significant impact on the change of NPP. In addition to the 2005-2009 period, the land conversion in other periods leads to the decrease of the total amount of NPP. Through the baseline range of 2001 cultivated land and 2013 building land use, NPP reduces land cover and NPP in a significant and extremely significant range. The main reason for the significant decrease in the NPP mean of the three ranges was the large scale expansion of the city and the large reduction of the cultivated land. The NPP loss (NPPlulc) caused by land use and land cover change was significantly different in space. During the study, the mean NPPlulc in the central area was up to 1353.05 g C/m2, followed by the study. The southern section is 1248.21 g C/m2, and the lowest 521.83 g C/m2. in the northeast region is in space change. The difference of different direction samples, due to the different intensity of urban development and land cover change, leads to the obvious difference in NPPlulc, and the sample NPPlulc in the center to the East, the South and the north is significantly reduced (P0.01). (6) the climate change has a significant influence. NPP changes. The NPP of different seasons, different seasons, different months and different types of coverage are positively correlated with the temperature and solar radiation, and it has a negative correlation with precipitation. The influence of three climatic factors on NPP, the change of NPP in most areas of the study area is mainly controlled by temperature and solar radiation, and precipitation often becomes a limiting factor for the accumulation of NPP. The terrain factors greatly affect the change of NPP in woodland, and the influence of altitude on the NPP of woodland is much greater than that of slope and slope to the NPP of woodland. (7) there is a significant difference between the influence and influence of climate and land cover change on NPP. In the time scale, the climate and land cover change resulted in the decrease of NPP by 0.2892 T g C, respectively. And 0.4239 T g C. woodlands, especially evergreen broad-leaved forests, are sensitive to climate change, and the land types, such as cultivated land, farmland forest transition zone and urban green space (grassland, grass and woody grassland), are mainly affected by land cover changes, such as cultivated land, farmland and forest, and in the spatial scale, the NPP of northeast region is mostly affected by climate change. In the northern, Eastern and southern parts of the area, NPP is more affected by land cover change. NPP in the central area of the central area is mostly influenced by the two.
【学位授予单位】：中山大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q948

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