【作者】 王磊；

【导师】 刘世荣；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2010， 博士

【摘要】 气候变化对全球陆地生态系统相关过程产生了重要影响,已经成为陆地生态系统中碳循环研究的重要内容。集成生物圈模型(IBIS,Integrated Biosphere Simulator)将地表与水文过程、陆地生物地球化学循环,以及植被动态等整合到一个一体化的模型中,可以更加深入地分析全球碳循环过程受到生物物理学、生物地球化学和植被动态等时间尺度截然不同的自然过程的影响,得到较广泛的应用。本文通过以中国东部南北样带为对象,以大尺度陆面生态系统模型IBIS为工具,研究植被净初级生产力(NPP)的分布及动态变化规律,探讨东部南北样带植被碳源/汇格局,分析影响植被NPP变化的主要气候驱动因子,阐明气候因素对植被NPP分布格局形成机制的影响,并预测四种未来气候变化条件下的植被NPP分布规律。主要有以下研究结论:(1)东部南北样带植被NPP时空变化特征1957～2006年样带植被NPP年平均值分布总体上呈现随纬度升高而降低的趋势;各气候区中,植被NPP年平均值最高的是中亚热带(761.7 gC/m2/Yr),最低的是南温带(193.6 gC/m2/Yr);不同植被类型中,热带落叶林(773.2 gC/m2/Yr)NPP年平均值最高,热带稀树草原(157.3gC/m2/Yr)最低。1957～2006年样带植被NPP总量年际变化总体呈显著增加趋势,50年间NPP总量的变化范围为1.41 Gt C/Yr至1.72Gt C/Yr,50年间NPP总量多年平均值为1.54Gt C/Yr,约占全国NPP总量的80%;季节变化尺度上,NPP增长最快的夏季和春季,分别平均增长0.0014Gt C/Yr和0.0012Gt C/Yr,占全年NPP增长的46.67%和40.00%,秋季、冬季NPP增长较慢,共占全年增长比例的13.33%;植被NPP月际变化呈现正态单峰曲线分布,最大值出现在6月份,达到0.24 Gt C/Yr,其次是7月份和5月份,最低是12月份。1957～2006年东部南北样带植被年平均NPP值增加区域占整个样带的83.56%,减少区域只占16.44%,而且NPP增加达到显著性水平的占29.19%;植被NPP绝对增加量最大的类型是温带常绿针叶林、密灌丛和热带落叶林区,植被NPP相对增加最大的是北方常绿林、温带常绿针叶林和苔原区。各种植被类型在不同温度梯度上的植被NPP呈现不同的变化趋势。热带常绿林年平均NPP相对增加速率最大的是多年平均温度处于5℃～10℃的区域,热带落叶林年平均NPP相对增加速率最大的是多年平均温度处于5℃～10℃的区域,温带常绿针叶林年平均NPP相对增加速率最大的是多年平均温度处于10℃～15℃的区域,温带落叶林年平均NPP相对增加速率最大的是多年平均温度处于0℃～5℃的区域,北方常绿林年平均NPP相对增加速率最大的是多年平均温度处于-10℃～0℃的区域,混交林年平均NPP相对增加速率最大的是多年平均温度处于0℃～5℃的区域,热带稀树草原年平均NPP相对增加速率最大的是多年平均温度处于0℃～5℃的区域,草地年平均NPP相对增加速率最大的是多年平均温度处于15℃～20℃的区域,密灌丛年平均NPP相对增加速率最大的是多年平均温度处于5℃～10℃的区域,苔原年平均NPP相对增加速率最大的是多年平均温度处于-10℃～0℃的区域。(2)东部南北样带植被NPP变化与气候变化关系1957～2006年中国东部南北样带年平均气温、四季平均气温总体上均呈上升趋势,北部地区上升趋势高于南部。50年来,样带最北部和中南部地区降水增多,尤其以中南部降水增加的幅度最大(0～51.39mm/10a),样带中部地区降水呈明显降低的趋势(-30～0mm/10a)。气候变化对植被NPP年平均值空间分布格局影响上,占整个样带28.14%的区域为温度型,即NPP的时间变异只与年均温度呈显著性相关关系;5.54%的区域为降水型,即NPP时间变异只与年降水量呈显著性相关关系;2.07%的区域为温度、降水型,即与年均温呈显著相关关系,又与年降水量呈显著相关关系;64.25%的区域为复杂型,它与年均温度、年降水量均无显著相关关系,NPP的影响制约因素较多。东部南北样带植被NPP的时间变化趋势主要受温度控制。一年四季温度变化对植被NPP时间变化趋势影响较大,其中春季、夏季平均温度与植被NPP时间变化趋势都呈显著相关关系,而秋季、冬季未达到显著关系。一年四季平均降水量对植被NPP时间变化趋势的影响较小,都未达到显著相关关系。(3)不同气候变化情景下植被NPP格局变化的预测到本世纪末,四种未来气候变化情景中,CGCM3_SresA2气候情景时NSTEC植被年NPP平均值最大,达到1.64Gt C,其次是CGCM3_SresB1气候情景,为1.62 Gt C,最低的是HadCM3_HC3GG气候情景,为1.55 Gt C。四种未来气候变化情景下,东部南北样带植被NPP都呈现显著的增加趋势,但CGCM3_SresA2情景时,表现出最高的增加量,达到0.0006Gt C/Yr,增长最慢的是HadCM3_HC3GG情景,为0.0001Gt C/Yr。更多还原

【Abstract】 Climate change is increasingly affecting land surface processes of terrestrial ecosystem, which has become one of research focuses in terrestrial carbon cycle. IBIS (Integrated Biosphere Simulator) model integrates the surface and hydrological processes, terrestrial biogeochemical cycles, and vegetation dynamics into a whole model. It is widely used for contributing to be more in-depth analysis of the global carbon cycle affected by bio-physics, biogeochemistry and vegetation dynamics.By means of IBIS model, the spatial distributions and dynamic change of vegetation NPP along the North South Transect of East China (NSTEC) were explored in order to identify the temporal and spatial patterns of vegetation carbon source and sink, and to ascertain the driving factors underlying the changes of vegetation NPP. The research results will help to improve the understanding of the mechanism of climatic change impact on vegetation NPP variation, and further to project the likely changes in vegetation NPP under various scenarios of climate changes in the future.The main results were as follows:1) Spatial-temporal variation of vegetation NPP along the North South Transect of East ChinaIn general, the annual mean NPP value tends to decline with latitude during the period from 1957 to 2006. Among the various climate zones, the highest annual mean NPP value (761.7 gC/m2/Yr) was in the middle subtropics, and the lowest (193.6 gC/m2/Yr) was in the South Temperate Zone. Among the various vegetation types, the highest (773.2 gC/m2/Yr) was the tropical deciduous forest had, while the lowest(157.3gC/m2/Yr)was in the savanna.Inter-annual vegetation NPP during the past 50 years showed an increasing trend, with the annual NPP value ranging from 1.41Gt C/Yr to 1.72 Gt C/Yr and the average of 1.54 Gt C/Yr, which accounted for 80% of the whole country. The seasonal patterns of NPP were found to increase rapidly in summer and spring, with about 0.0014Gt C/Yr and 0.0012Gt C/Yr increased, accounting for 46.67% and 40% of its annual increment, while NPP increased slowly in autumn and winter, accounting for 13.33%. Monthly vegetation NPP variation was characterized with a single peak curve of normal distribution (the peak of 0.24Gt C/Yr), which occurred in June, followed by in July and May, and the lowersest in December.The annual mean NPP in an area basis along the NSTEC during the past 50 years indicated that 83.56% of the total area increased while 16.44% declined. The absolute increment of NPP occurred in the temperate evergreen conifer forest, dense shrubland and tropical deciduous forest, while the relative increment of NPP occurred in the boreal evergreen forest, temperate evergreen conifer forest and tundra.NPP patterns varied with vegetation types and temperature gradients. The most relative increment rate of the annual mean NPP of tropical evergreen forest and tropical deciduous forest occurred in the area where the annual average temperature (AAT) was 5~10℃. For the temperate evergreen conifer forest and the temperate deciduous forest, AATs were 10~15℃and 0~5℃, respectively. The AAT for the boreal evergreen forest was -10~0℃, while for mixed forest, AAT was 0~5℃. The AATs of the Savanna and grassland were 0~5℃and 15~20℃A, respectively. For dense shrubland and tundra, their AATs were 5~10℃and -10~0℃, respectively.2) Relationship between vegetation NPP changes and climate changes along the NSTEC. Both Annual and seasonal mean temperature showed an increasing trend during the past 50 years, with notable increment in the Norther areas. Precipitation increased in the northern part and central southern regions, while decreased significantly in the the central area of the NSTEC.Based on the spatial distribution of annual mean NPP affected by climate changes, it indicated that the temperature based NPP impact accounted for 28.14% of the total transect area, suggesting the temporal variation of NPP was significantly affected by AAT. Precipitation based NPP impact accounted for 5.54% of the total transect areas, showing that the temporal variation of NPP was significantly affected by annual precipitation. The combined temperature and precipitation based NPP impacts accounted for 2.07% of the total transect area, indicating the temporal variation of NPP were significantly affected by AAT and annual precipitation as well. The complex components accounted for 64.25%, which was affected by other factors in addition to AAT and annual precipitation. Temporal variation of NPP along the NSTEC was mainly controlled by temperature. The temporal variations of NPP in spring and summer were significantly correlated to its seasonal mean temperature. Annual precipitation had less influence on the temporal variation of NPP.3) Projections of NPP pattern change under climate change scenarios in futureAmong the four scenarios of climate changes in future, the maximum vegetation NPP of the NSTEC occurs under the CGCM3_SresA2, with the value of 1.64Gt C, follows by cenario CGCM3_SresB1 with the value of 1.62Gt C, and the lowest occurs under the HadCM3_HC3GG with the value of 1.55 Gt C.For the four scenarios, vegetation NPP of the NSTEC shows an increasing tendency, with the largest increment value of 0.0006Gt C/Yr under the CGCM3_SresA2 and the lowest incement value of 0.0001Gt C/Yr under the HadCM3_HC3GG.更多还原