1981—2000年内蒙古中部地区植被净初级生产量变化研究

基于AVHRR GLOPEM NPP数据集及相应时段的气候数据集,通过对逐个像元信息的提取与分析,研究了1981—2000年内蒙古中部地区植被净初级生产量退化的状况及其与气候变化的相关性。结果显示:1)该区植被净初级生产量的空间分布大致由东向西呈减少的趋势,年际变化比较明显,尤其是在1990—2000年,减少率达10.32gC/m2.a;2)1981—2000年,植被净初级生产量年际变化的区域差异比较明显;3)植被净初级生产量年际变化与气候因子年际变化的相关性存在比较明显的区域差异;4)不同植被类型对气候变化表现出不同的响应特征,该区降水量年际变化对植被的影响要高于气温年际变化对其的影响。本研究有助于了解内蒙古中部地区植被净初级生产量退化的状况以及影响其退化的气候因素,可为退化植被的生态修复提供有意义的参考。     

气候变化对漳州市植被生态影响分析

植被净第一性生产力(NPP)是反映植被生态的重要因子,通过NPP对区域植被生态变化进行研究具有重要的意义.基于气候影响的自然植被的净第一性生产力模型,应用线性倾向值估计等统计方法,分析1981-2016年漳州市气候变化及NPP变化特征.结果表明,漳州市气候呈现气温显著升高、降水增多的暖湿化倾向,全市NPP年平均值随年际变化,并呈微略增加趋势,NPP年际总体波动幅度小,植被生产力较为稳定.漳州市NPP分布具有明显的县域差别,漳州南部县(东山、诏安)为NPP最小值区,而中部县(南靖、平和、云霄县)为最大值区,内陆山区县NPP值总体较沿海县市大.NNP空间分布呈现由东南部向西北部、南部向北部递增的分布态势,但各县市各年代NPP值都保持较为稳定,有利于漳州市良好生态的维持.漳州市降水与其NPP呈显著正相关,降水对NPP有着重要影响作用.     

北部湾沿海流域植被覆盖动态变化及其驱动因素

基于2000—2018年的中分辨率成像光谱仪13Q1数据,利用修正的变化矢量分析、变异系数、Hurst指数等方法分析北部湾沿海流域植被覆盖动态变化趋势及其持续性、预测未来植被覆盖变化情况以及植被覆盖变化的驱动因素.研究表明:北部湾沿海流域植被覆盖度较高,且年际变化幅度较小,多年植被指数均值表现出从陆地到滨海、从流域外边界到河流中心逐渐递减的规律.2000—2018年以来,流域内植被覆盖改善区域(73.6％)大于退化区域(26.3％),河口、滨海区不仅为植被退化明显区域,且为植被变化波动性较强区域.未来流域内植被覆盖变化波动性较强,其中持续改善区域仅占19.6％,持续退化区域占8％,其余的72.4％为波动性变化区域.流域内植被覆盖变化趋势与人为因素和气候因素相关性较高,与地形特征相关性较低.     

气候变化对中国北方季风区生态系统总初级生产量的影响评价

利用中国北方季风区121个地表气象观测站2000-2013年逐日气温和降水资料及MODIS遥感8天平均总初级生产量数据(MOD17A2), 分别建立了14年内8天累积平均、最低、最高气温和降雨量与累积总初级生产量的线性气候相关模型。基于模型所得区间的阈值和参数, 计算区域模式RSM本底时期10年(1996-2005年)及未来 10年(2041-2050年)两种排放情景RCP4.5和RCP8.5下, 森林、草地和农田生态系统总初级生产量累积开始日期、累积时期、累积结束日期及累积速率变化, 分析平均、最高、最低气温和降水量变化对总初级生产量累积的影响, 并综合评价气候变化对生态系统总初级生产量累积的影响。结果表明: 平均气温和最低气温对总初级生产量的模拟精度高于最高气温和降雨量; 总初级生产量累积开始和结束日期对4 类气候因子的变化均较敏感, 而累积时期和累积速率仅对平均气温和最高气温的变化较敏感; 未来气候变化将延长累积时期, 增加累积速率, 并提高总初级生产量。     

基于CASA模型的皖江城市带植被净初级生产力时空变化特征研究

运用GIS和RS技术,利用植被、气候和辐射等地面空间数据,基于CASA模型估算2001-2010年之间皖江城市带植被净初级生产力(NPP),并分析其时空变化特征.结果表明:10年之间皖江城市带植被净初级生产力呈减少趋势,其中NPPMAX年均减少速度5.3gC/m2·a,NPPMEAN年均减少率0.513%;10年NPPMAX均值为805.09gC/m2·a,NPPMEAN均值为463.26gC/m2·a;净初级生产力年累计量变化幅度较大,约在30.052-43.483TgC/a之间;年际变化十分明显,最大值出现在2008年,为43.483TgC,最小值在2006年,为30.052TgC,年均减少率0.51%.植被净初级生产力空间格局表现出较大的不均匀性,整体分布状况是以长江为界,长江以南植被净初级生产力较大,但有逐渐变小趋势;长江以北植被净初级生产力较小,却表现出逐渐增加的趋势.     

区域尺度植被降水利用效率的时空变化特征——以洮河流域为例

采用CASA模型估算洮河流域植被净初级生产力和降水利用效率,利用Sen斜率和相关性分析方法量化分析洮河流域2001-2010年植被降水利用效率的时空变化特征及气候关联.结果表明:2001-2010年洮河流域平均降水利用效率为0.73 g/(m~2·mm),青藏高原东北缘高于黄土高原西南缘;不同植被类型的降水利用效率差别较大,阔叶林最高,裸地最低;降水利用效率越高年际波动越明显.统计期间,流域降水利用效率整体表现出增长趋势,发生显著变化的区域主要分布于青藏片区中东部和黄土片区中北部;空间分析表明,洮河流域大部分区域的降水利用效率与降水量呈现较高的负相关性,两区相比,青藏片区更加显著.     

江阴市植被净初级生产力及碳汇价值分析

利用遥感影像、逐日气象观测记录等相关数据,应用基于过程的生物地球化学模型(BEPS),对江阴市市域范围内的土地利用状况及年净初级生产力进行了研究,并对植被系统C02吸收功能的价值进行了估算.结果表明:1991-2002年,江阴市陆地生态系统的总平均NPP由818 g/(m2·a)下降为699 g/(m2·a),其生态系统服务的碳汇价值也下降了0.88亿元.期间江阴市建设用地面积扩张及由此导致的林地、农田面积萎缩,成为江阴市陆地生态系统年净初级生产力下降的主要原因,森林植被质量变化对区域NPP下降的影响较小,而气候变化产生的影响不明显.     

青藏高原2000-2015年草地质量的时空变化研究

基于植被净初级生产力（net primary productivity,NPP）和归一化植被指数（normalized difference vegetation index,NDVI）合成了综合草地等级指数（grassland degree index,GDI）,计算了青藏高原2000-2015年草地质量变化的程度和速率,综合分析了草地退化的影响机制.研究表明：2000-2015年,青藏高原Ⅰ级（优质）草地区和Ⅳ级（劣质）草地区的面积比例基本保持不变;Ⅰ级草地区中约28.11%变为Ⅱ级;Ⅱ级草地区转化为Ⅰ级和Ⅲ级的比例分别为18.19%和21.53%;Ⅲ级草地区约有28.54%转变为Ⅳ级.由此可见,2000-2015年间,青藏高原草地经历了退化-恢复-退化的过程：高原北部大部分地区草地质量变化不明显,且呈现好转的趋势;南部和东部地区普遍出现草地退化现象,其中局部地区退化情况较为严重.     

珠江三角洲植被对区域碳氧平衡的作用

珠江三角洲植被的净生产量为3 855×107t a,碳净固定量为1.822×107t,氧气释放总量为4.860×107t a。而该区域的碳释放总量高达3.600×107t a,是该区植被固碳能力的2.0倍,其中66.05%的碳来源于燃料燃烧。该区的耗氧总量达1.635×108t,是该区植被氧气释放量的3.4倍。这表明珠江三角洲是华南地区的重要碳源。研究结果表明,珠江三角洲植被的生物量和净生产量较低,如能加强植被的保护,提高植被的生物量和净生产量,则区域植被对碳氧平衡的作用会大大提高。     

2000-2015年黄淮地区城市扩展的地表辐射调节作用研究

土地利用变化能够改变地表反照率从而可以影响区域乃至全球的气候变化.为分析和验证地表反照率变化导致的年际辐射强迫作用,本研究选取了2000-2015年中国城镇化发展迅速,同时区域差异明显的黄淮地区7个省市作为研究区域,利用遥感及土地利用数据分析该区域地表反照率变化的时空特征,以及城市扩展导致的气候效应.结果表明:(1)7省市城区土地面积均明显增加,从2000年的12 447 km2增长到2015年的19 987 km2,扩展面积为原有的1.61倍;(2)7省市的老城区与扩展城区平均地表反照率的时空差异程度,呈波动下降趋势.且太阳辐射总体亦呈下降态势,但空间分布差异较小,年际变化差异较大;(3)2000-2015年的对比结果显示,黄淮7省市城区平均辐射强迫为正值,增加达0.398 6W· m-2,整体表现为增温效应,但安徽省、江苏省却表现出降温效应.本研究从辐射平衡角度探讨城市扩展对温度的影响,并进一步揭示出2000年以来城市建设在城区绿化和植被管护方面带来的辐射强迫作用和气候效应.     

Fire as the dominant driver of central Canadian boreal forest carbon balance

Changes in climate, atmospheric carbon dioxide concentration and fire regimes have been occurring for decades in the global boreal forest, with future climate change likely to increase fire frequency--the primary disturbance agent in most boreal forests. Previous attempts to assess quantitatively the effect of changing environmental conditions on the net boreal forest carbon balance have not taken into account the competition between different vegetation types on a large scale. Here we use a process model with three competing vascular and non-vascular vegetation types to examine the effects of climate, carbon dioxide concentrations and fire disturbance on net biome production, net primary production and vegetation dominance in 100 Mha of Canadian boreal forest. We find that the carbon balance of this region was driven by changes in fire disturbance from 1948 to 2005. Climate changes affected the variability, but not the mean, of the landscape carbon balance, with precipitation exerting a more significant effect than temperature. We show that more frequent and larger fires in the late twentieth century resulted in deciduous trees and mosses increasing production at the expense of coniferous trees. Our model did not however exhibit the increases in total forest net primary production that have been inferred from satellite data. We find that poor soil drainage decreased the variability of the landscape carbon balance, which suggests that increased climate and hydrological changes have the potential to affect disproportionately the carbon dynamics of these areas. Overall, we conclude that direct ecophysiological changes resulting from global climate change have not yet been felt in this large boreal region. Variations in the landscape carbon balance and vegetation dominance have so far been driven largely by increases in fire frequency.     

Europe-wide reduction in primary productivity caused by the heat and drought in 2003

Future climate warming is expected to enhance plant growth in temperate ecosystems and to increase carbon sequestration. But although severe regional heatwaves may become more frequent in a changing climate, their impact on terrestrial carbon cycling is unclear. Here we report measurements of ecosystem carbon dioxide fluxes, remotely sensed radiation absorbed by plants, and country-level crop yields taken during the European heatwave in 2003. We use a terrestrial biosphere simulation model to assess continental-scale changes in primary productivity during 2003, and their consequences for the net carbon balance. We estimate a 30 per cent reduction in gross primary productivity over Europe, which resulted in a strong anomalous net source of carbon dioxide (0.5 Pg C yr(-1)) to the atmosphere and reversed the effect of four years of net ecosystem carbon sequestration. Our results suggest that productivity reduction in eastern and western Europe can be explained by rainfall deficit and extreme summer heat, respectively. We also find that ecosystem respiration decreased together with gross primary productivity, rather than accelerating with the temperature rise. Model results, corroborated by historical records of crop yields, suggest that such a reduction in Europe's primary productivity is unprecedented during the last century. An increase in future drought events could turn temperate ecosystems into carbon sources, contributing to positive carbon-climate feedbacks already anticipated in the tropics and at high latitudes.     

阔叶红松林净初级生产力对气候变化响应模拟

为研究气候变化对小兴安岭阔叶红松林的影响,应用生态系统过程模型PnET-Ⅱ,分别模拟现行气候和未来气候下阔叶红松林净初级生产力(NPP)的变化.结果显示,近43年来阔叶红松林NPP无明显变化趋势.在两种未来气候模拟方案下,阔叶红松林NPP变化趋势都是先增加后减少,但不同的气候模拟方案下,变化幅度略有差异.该成果可为气候变化下阔叶红松林的合理经营提供参考.     

Net production of oxygen in the subtropical ocean

The question of whether the plankton communities in low-nutrient regions of the ocean, comprising 80% of the global ocean surface area, are net producers or consumers of oxygen and fixed carbon is a key uncertainty in the global carbon cycle. Direct measurements in bottle experiments indicate net oxygen consumption in the sunlit zone, whereas geochemical evidence suggests that the upper ocean is a net source of oxygen. One possible resolution to this conflict is that primary production in the gyres is episodic and thus difficult to observe: in this model, oligotrophic regions would be net consumers of oxygen during most of the year, but strong, brief events with high primary production rates might produce enough fixed carbon and dissolved oxygen to yield net production as an average over the annual cycle. Here we examine the balance of oxygen production over three years at sites in the North and South Pacific subtropical gyres using the new technique of oxygen sensors deployed on profiling floats. We find that mixing events during early winter homogenize the upper water column and cause low oxygen concentrations. Oxygen then increases below the mixed layer at a nearly constant rate that is similar to independent measures of net community production. This continuous oxygen increase is consistent with an ecosystem that is a net producer of fixed carbon (net autotrophic) throughout the year, with episodic events not required to sustain positive oxygen production.     

Stability of alpine meadow ecosystem on the Qinghai- Tibetan Plateau

THE QINGHAI-TIBETAN PLATEAU PLAYS AN IMPORTANT ROLE IN THE ATMOSPHERIC CIRCULATION AND REGIONAL MONSOON CLIMATE, WHICH HAS GREAT INFLUENCE ON THE REGIONAL AND GLOBAL CLIMATE. THUS, THE CHANGE OF THE QINGHAI-TIBETAN PLATEAU ECOSYSTEM IS EXPECTED TO AFFECT …     

1982—1999年我国植被净第一性生产力及其时空变化

基于地理信息系统和卫星遥感技术,利用植被、气候和土壤等地面空间数据,应用CASA模型估算了1982—1999（除1994）年间我国植被年净第一性生产量及其时空变化。结果表明：18年间我国植被净第一性生产量呈增加趋势,平均增加速率为0.024PgC·a^-1,其均值为1.8PgC,其中高寒植被、常绿阔叶林和常绿针叶林的增加速度最快;降水是限制我国植被净第一性生产力的主要因子。     

Ecosystem vulnerability of China under B2 climate scenario in the 21st century

This paper applies climate change scenarios in China based on the SRES assumptions with the help of RCMs projections by PRECIS （providing regional climates for impacts studies） system introduced to China from.the Hadley Centre for Climate Prediction and Research at a high-resolution （50 kmx50 km） over China. This research focuses on B2 scenario of SRES. A biogeochemical model ＂Atmosphere Vegetation Integrated Model （AVIM2）＂ was applied to simulating ecosystem status in the 21st century. Then vulnerability of ecosystems was assessed based on a set of index of mainly net primary production （NPP） of vegetation. Results show that climate change would affect ecosystem of China severely and there would be a worse trend with the lapse of time. The regions where having vulnerable ecological background would have heavier impacts while some regions with better ecological background would also receive serious impacts. Extreme climate even would bring about worse impact on the ecosystems. Open shrub and desert steppe would be the two most affected types. When the extreme events happen, vulnerable ecosystem would extend to part of defoliate broad-leaved forest, woody grassland and evergreen conifer forest. Climate change would not always be negative. It could be of some benefit to cold region during the near-term. However, in view of mid-term to long-term negative impact on ecosystem vulnerability would be enormously.     

Bacterial growth and primary production along a north-south transect of the Atlantic Ocean

The oceanic carbon cycle is mainly determined by the combined activities of bacteria and phytoplankton, but the interdependence of climate, the carbon cycle and the microbes is not well understood. To elucidate this interdependence, we performed high-frequency sampling of sea water along a north-south transect of the Atlantic Ocean. Here we report that the interaction of bacteria and phytoplankton is closely related to the meridional profile of water temperature, a variable directly dependent on climate. Water temperature was positively correlated with the ratio of bacterial production to primary production, and, more strongly, with the ratio of bacterial carbon demand to primary production. In warm latitudes (25 degrees N to 30 degrees S), we observed alternating patches of predominantly heterotrophic and autotrophic community metabolism. The calculated regression lines (for data north and south of the Equator) between temperature and the ratio of bacterial production to primary production give a maximum value for this ratio of 40% in the oligotrophic equatorial regions. Taking into account a bacterial growth efficiency of 30%, the resulting area of net heterotrophy (where the bacterial carbon demand for growth plus respiration exceeds phytoplankton carbon fixation) expands from 8 degrees N (27 degrees C) to 20 degrees S (23 degrees C). This suggests an output of CO2 from parts of the ocean to the atmosphere.     

Global patterns in human consumption of net primary production

The human population and its consumption profoundly affect the Earth's ecosystems. A particularly compelling measure of humanity's cumulative impact is the fraction of the planet's net primary production that we appropriate for our own use. Net primary production--the net amount of solar energy converted to plant organic matter through photosynthesis--can be measured in units of elemental carbon and represents the primary food energy source for the world's ecosystems. Human appropriation of net primary production, apart from leaving less for other species to use, alters the composition of the atmosphere, levels of biodiversity, energy flows within food webs and the provision of important ecosystem services. Here we present a global map showing the amount of net primary production required by humans and compare it to the total amount generated on the landscape. We then derive a spatial balance sheet of net primary production 'supply' and 'demand' for the world. We show that human appropriation of net primary production varies spatially from almost zero to many times the local primary production. These analyses reveal the uneven footprint of human consumption and related environmental impacts, indicate the degree to which human populations depend on net primary production 'imports' and suggest policy options for slowing future growth of human appropriation of net primary production.     

陆地生态系统生产力模型研究进展

目的 通过净初级生产力(NPP)模型研究回顾,为全球陆地碳循环和全球变化等研究提供方法参考.方法 把生产力模型大致归为3类,分别阐述其研究进展.结果 气候相关模型通过对气候因子与植物干物质生产的相关性分析来估算植被的净初级生产力;生物地球化学循环模型以气候、土壤条件和植被类型为输入变量,主要模拟破、水和营养物质的循环;基于遥感资料的模型基于植被指数与冠层吸收的光合有效辐射部分之间的关系得到吸收光合有效辐射,进而建立大尺度的卫星观测与生物生产力的关系.结论 无论应用哪种生产力模型,都受到较多条件的限制,因此,目前应用模型计算净初级生产力仍存在一些不足之处.