Characteristics of permafrost degradation in Northeast China and its ecological effects: A review

Latitudinal permafrost in Northern Northeast(NNE)China is located in the southern margin of the Eurasian continent,and is very sensitive to climatic and environmental change.Numerical simulations indicate that air temperature in the permafrost regions of Northeast China has been on the rise since the 1950s,and will keep rising in the 21st century,leading to extensive degradation of permafrost.Permafrost degradation in NNE China has its own characteristics,such as northward shifts in the shape of a"W"for the permafrost southern boundary(SLP),discontinuous permafrost degradation into islandlike frozen soil,and gradually disappearing island permafrost.Permafrost degradation leads to deterioration of the ecological environment in cold regions.As a result,the belt of larch forests dominated by Larix gmelinii has shifted northwards and wetland areas with symbiotic relationships with permafrost have decreased significantly.With rapid retreat and thinning of permafrost and vegetation change,the CO2 and CH4 flux increases with mean air temperature from continuous to sporadic permafrost areas as a result of activity of methanogen enhancement,positively feeding back to climate warming.This paper reviews the features of permafrost degradation,the effects of permafrost degradation on wetland and forest ecosystem structure and function,and greenhouse gas emissions on latitudinal permafrost in NNE China.We also put forward critical questions about the aforementioned effects,including:(1)establish long-term permafrost observation systems to evaluate the distribution of permafrost and SLP change,in order to study the feedback of permafrost to climate change;(2)carry out research about the effects of permafrost degradation on the wetland ecosystem and the response of Xing'an larch to global change,and predict ecosystem dynamics in permafrost degradation based on long-term field observation;(3)focus intensively on the dynamics of greenhouse gas flux in permafrost degradation of Northeast China and the feedback of greenhouse gas emissions to climate change;(4)quantitative studies on the permafrost carbon feedback and vegetation carbon feedback due to permafrost change to climate multi-impact and estimate the balance of C in permafrost regions in the future.     

Three-dimensional modelling of soil organic carbon density and carbon sequestration potential estimation in a dryland farming region of China

Soil organic carbon density(SOCD) and soil organic carbon sequestration potential(SOCP) play an important role in carbon cycle and mitigation of greenhouse gas emissions. However, the majority of studies focused on a two-dimensional scale, especially lacking of field measured data. We employed the interpolation method with gradient plane nodal function(GPNF) and Shepard(SPD) across a range of parameters to simulate SOCD with a 40 cm soil layer depth in a dryland farming region(DFR) of China. The SOCP was estimated using a carbon saturation model. Results demonstrated the GPNF method was proved to be more effective in simulating the spatial distribution of SOCD at the vertical magnification multiple and search point values of 3.0×10~6 and 25, respectively. The soil organic carbon storage(SOCS) of 40 cm and 20 cm soil layers were estimated as 22.28×10~(11) kg and 13.12×10~(11) kg simulated by GPNF method in DFR. The SOCP was estimated as 0.95×10~(11) kg considered as a carbon sink at the 20–40 cm soil layer. Furthermore, the SOCP was estimated as –2.49×10~(11) kg considered as a carbon source at the 0–20 cm soil layer. This research has important values for the scientific use of soil resources and the mitigation of greenhouse gas emissions.     

空间溢出视角下经济集聚对水污染物排放的影响——基于中国 339 个地级及以上城市数据的实证分析（英文）

Whether economic agglomeration can promote improvement in environmental quality is of great importance not only to China's pollution prevention and control plans but also to its future sustainable development. Based on the COD(Chemical Oxygen Demand) and NH3-N(Ammonia Nitrogen) emissions Database of 339 Cities at the city level in China, this study explores the impact of economic agglomeration on water pollutant emissions, including the differences in magnitude of the impact in relation to city size using an econometric model. The study also examines the spillover effect of economic agglomeration, by conducting univariate and bivariate spatial autocorrelation analysis. The results show that economic agglomeration can effectively reduce water pollutant emissions, and a 1% increase in economic agglomeration could lead to a decrease in COD emissions by 0.117% and NH_3-N emissions by 0.102%. Compared with large and megacities, economic agglomeration has a more prominent effect on the emission reduction of water pollution in small-and medium-sized cities. From the perspective of spatial spillover, the interaction between economic agglomeration and water pollutant emissions shows four basic patterns: high agglomeration–high emissions, high agglomeration–low emissions, low agglomeration–high emissions, and low agglomeration–low emissions. The results suggest that the high agglomeration–high emissions regions are mainly distributed in the Beijing–Tianjin–Hebei region, Shandong Peninsula, and the Harbin-Changchun urban agglomeration; thus, local governments should consider the spatial spillover effect of economic agglomeration in formulating appropriate water pollutant mitigation policies.     

中国城市能源消费碳排放的区域差异、空间溢出效应及影响因素分析（英文）

Data show that carbon emissions are increasing due to human energy consumption associated with economic development. As a result, a great deal of attention has been focused on efforts to reduce this growth in carbon emissions as well as to formulate policies to address and mitigate climate change. Although the majority of previous studies have explored the driving forces underlying Chinese carbon emissions, few have been carried out at the city-level because of the limited availability of relevant energy consumption statistics. Here, we utilize spatial autocorrelation, Markov-chain transitional matrices, a dynamic panel model, and system generalized distance estimation(Sys-GMM) to empirically evaluate the key determinants of carbon emissions at the city-level based on Chinese remote sensing data collected between 1992 and 2013. We also use these data to discuss observed spatial spillover effects taking into account spatiotemporal lag and a range of different geographical and economic weighting matrices. The results of this study suggest that regional discrepancies in city-level carbon emissions have decreased over time, which are consistent with a marked spatial spillover effect, and a ‘club' agglomeration of high-emissions. The evolution of these patterns also shows obvious path dependence, while the results of panel data analysis reveal the presence of a significant U-shaped relationship between carbon emissions and per capita GDP. Data also show that per capita carbon emissions have increased in concert with economic growth in most cities, and that a high-proportion of secondary industry and extensive investment growth have also exerted significant positive effects on city-level carbon emissions across China. In contrast, rapid population agglomeration, improvements in technology, increasing trade openness, and the accessibility and density of roads have all played a role in inhibiting carbon emissions. Thus, in order to reduce emissions, the Chinese government should legislate to inhibit the effects of factors that promote the release of carbon while at the same time acting to encourage those that mitigate this process. On the basis of the analysis presented in this study, we argue that optimizing industrial structures, streamlining extensive investment, increasing the level of technology, and improving road accessibility are all effective approaches to increase energy savings and reduce carbon emissions across China.     

中国碳排放对国际贸易影响的经验分析(英文)

International trade is an important impact factor to the carbon emissions of a country.As the rapid development of Chinese foreign trade since its entry into the WTO in 2002,the effects of international trade on carbon emissions of China are more and more significant.Using the recent available input-output tables of China and energy consumption data,this study estimated the effects of Chinese foreign trade on carbon emissions and the changes of the effects by analyzing the emissions embodied in trade between 2002 and 2007.The re-sults showed a more and more significant exporting behavior of embodied carbon emissions in Chinese international trade.From 2002 to 2007,the proportion of net exported emissions and domestic exported emissions in domestic emissions increased from 18.32% to 29.79% and from 23.97% to 34.76%,respectively.In addition,about 22.10% and 32.29% of the total imported emissions were generated in processing trade in 2002 and 2007,respectively,which were imported and later exported emissions.Although,most of the sectors showed a growth trend in imported and exported emissions,sectors of electrical machinery and communication electronic equipment,chemical industry,and textile were still the biggest emission exporters,the net exported emissions of which were also the largest.For China and other developing countries,technology improvement may be the most favorable and acceptable ways to re-duce carbon emissions at present stage.In the future negotiations on emissions reduction,it would be more fair and reasonable to include the carbon emissions embodied in international trade when accounting the total emissions of an economy.     

Atmospheric Methane in Ice Cores

<正> The reconstruction of air trapped in ice cores provides us the most di-rect information about atmospheric CH_4 variations in the past history.Ice corerecords from the“Three Poles(Antarctica,Greenland and Tibetan Plateau)”re-veal the detailed fluctuations of atmospheric CH_4 concentration with time and areallowed to quantify the CH_4 differences among latitudes.These data are indis-pensably in the farther study of the relationship between greenhouse gases andclimatic change,and of the past changes in terrestrial CH_4 emissions.Ice coresreconstruction indicates that atmospheric CH_4 concentration has increased quicklysince industrialization,and the present day's level of atmospheric CH_4(1800 pp-by)is unprecedented during the past Glacial-Interglacial climate cycles.     

Carbon emissions trends with optimal balanced economic growth of China and the USA and some abatement options for China

It is believed that the global CO2 emissions have to begin dropping in the near fu- ture to limit the temperature increase within 2 degrees by 2100. So it is of great concern to environmentalists and national decision-makers to know how the global or national CO2 emissions would trend. This paper presented an approach to project the future CO2 emissions from the perspective of optimal economic growth, and applied this model to the cases of China and the United States, whose CO2 emissions together contributed to more than 40% of the global emissions. The projection results under the balanced and optimal economic growth path reveal that the CO2 emissions will peak in 2029 for China and 2024 for the USA owing to their empirically implied pace of energy efficiency improvement. Moreover, some abatement options are analyzed for China, which indicate that 1） putting up the energy price will de- crease the emissions at a high cost; 2） enhancing the decline rate of energy intensity can significantly mitigate the emissions with a modest cost; and 3） the energy substitution policy of replacing carbon intensive energies with clean ones has considerable potential to alleviate emissions without compromising the economic development.     

中国城镇化水平、经济增长和二氧化碳排放的面板协整和因果分析（英文）

Elucidating the complex mechanism between urbanization,economic growth,carbon dioxide emissions is fundamental necessary to inform effective strategies on energy saving and emission reduction in China. Based on a balanced panel data of 31 provinces in China over the period 1997–2010,this study empirically examines the relationships among urbanization,economic growth and carbon dioxide(CO2) emissions at the national and regional levels using panel cointegration and vector error correction model and Granger causality tests. Results showed that urbanization,economic growth and CO2 emissions are integrated of order one. Urbanization contributes to economic growth,both of which increase CO2 emissions in China and its eastern,central and western regions. The impact of urbanization on CO2 emissions in the western region was larger than that in the eastern and central regions. But economic growth had a larger impact on CO2 emissions in the eastern region than that in the central and western regions. Panel causality analysis revealed a bidirectional long-run causal relationship among urbanization,economic growth and CO2 emissions,indicating that in the long run,urbanization does have a causal effect on economic growth in China,both of which have causal effect on CO2 emissions. At the regional level,we also found a bidirectional long-run causality between land urbanization and economic growth in eastern and central China. These results demonstrated that it might be difficult for China to pursue carbon emissions reduction policy and to control urban expansion without impeding economic growth in the long run. In the short-run,we observed a unidirectional causation running from land urbanization to CO2 emissions and from economic growth to CO2 emissions in the eastern and central regions. Further investigations revealed an inverted N-shaped relationship between CO2 emissions and economic growth in China,not supporting the environmental Kuznets curve(EKC) hypothesis. Our empirical findings have an important reference value for policy-makers in formulating effective energy saving and emission reduction strategies for China.     

基于LMDI分解和STIRPAT模型的哈萨克斯坦能源碳排放影响因素的定量分析（英文）

Quantitative analysis of the impact factors in energy-related CO_2 emissions serves as an important guide for reducing carbon emissions and building an environmentally-friendly society. This paper aims to use LMDI method and a modified STIRPAT model to research the conventional energy-related CO_2 emissions in Kazakhstan after the collapse of the Soviet Union. The results show that the trajectory of CO_2 emissions displayed U-shaped curve from 1992 to 2013. Based on the extended Kaya identity and additive LMDI method, we decomposed total CO_2 emissions into four influencing factors. Of those, the economic active effect is the most influential factor driving CO_2 emissions, which produced 110.86 Mt CO_2 emissions, with a contribution rate of 43.92%. The second driving factor is the population effect, which led to 11.87 Mt CO_2 emissions with a contribution rate of 4.7%. On the contrary, the energy intensity effect is the most inhibiting factor, which caused –110.90 Mt CO_2 emissions with a contribution rate of –43.94%, followed by the energy carbon structure effect resulting in –18.76 Mt CO_2 emissions with a contribution rate of –7.43%. In order to provide an in-depth examination of the change response between energy-related CO_2 emissions and each impact factor, we construct a modified STIRPAT model based on ridge regression estimation. The results indicate that for every 1% increase in population size, economic activity, energy intensity and energy carbon structure, there is a subsequent increase in CO_2 emissions of 3.13%, 0.41%, 0.30% and 0.63%, respectively.     

作物气候风险研究:以河南省棉花为例

1 Introduction In the past 100 years the global temperature rose sharply due to the increase of greenhouse gas emissions into the atmosphere. The mean ground temperature rose by 0.5–0.6°C in the 20th century and 0.3–0.4°C in the last 20 years of the c…     

Impacts of land use and climate change on regional net primary productivity

Combined with recent historical climate data and two periods of land use data sets from remote sensing data, we test the net primary productivity (NPP) data sets in North China modelled by the satellite data-driven Global Production Efficiency Model (GLO-PEM) for detecting the widespread spatial and temporal characteristics of the impacts of climate and land use change on the regional NPP. Our results show that over the past 20 years, the mean annual temperature in the study region has remarkably increased by more than 0.064 oC, but over the same period, there has been a 1.49 mm decrease in annual precipitation and decrease in NPP by an annual rate of 6.9 TgC. The NPP changes in the study region were greatly affected by the average temperature and precipitation by ten-day periods as well as the seasonal temperature and precipitation in the study region. The correlation between seasonal NPP and seasonal precipitation and temperature is highly consistent with land cover spatially, and the correlation coefficient changes with the changes of vegetation types. The analysis reveals that the related areas in land use change only take up 5.45% of the whole studied region, so the climate changes dominate the impacts on the NPP in the whole study region (90% of the total). However, land use plays an absolute dominative role in areas with land cover changes, accounting for 97% of the total. From 1981 to 2000, the NPP in the whole study region remarkably reduced due to obvious precipitation decrease and temperature rise. Between two periods of land use (about 10 years), the changes in climate are predicted to promote a decrease in NPP by 78 (±0.6) TgC, and integrated impacts of climate changes and land use to promote a decrease in NPP by 87(±0.8) TgC.     

土地利用和气候变化对区域净初级生产力的影响

应用以遥感观测数据驱动的GLO-PEM模式模拟估计的中国北方20年的NPP数据同其20年气候数据结合,同时利用通过遥感宏观调查所得的两期土地利用数据,分析20年气候和土地利用变化对区域净初级生产力 (Net Primary Productivity,NPP) 的影响的时空特征。分析结果表明,20年来研究区域年均温度显著增加 (年均增温0.064 ^oC),年降水量明显减少 (年降水减少率为1.49 mm/年),NPP以减少趋势为主 (年减少率6.9 TgC)。研究区域NPP的变化受旬 (月) 均温和旬 (月) 降水量和季节温度和季节降水的变化影响显著。季节NPP同季节降水和温度的相关性在空间上同植被覆盖表现出高度的一致性,其相关系数大小随着不同植被覆盖类型变化而变化。通过分析可见,就整个研究区来说,发生土地利用变化的区域仅占整个研究区域的5.45%, 气候对整个研究区域NPP的影响占主导地位 (占了总影响量的90%);土地利用发生区域土地利用的作用占了绝对地位,土地利用的影响占了约97%。整个研究区域近20年来因为降水明显减少,温度显著升高,导致NPP明显下降,在两期土地利用间隔时间段内 (约10年) 因气候影响NPP减少了78 (±0.6) TgC。因为土地利用的变化导致NPP减少9 (±0.2) TgC。气候和土地利用共同作用是研究区域的NPP减少87 (±0.8) TgC。     

蒙古高原中部气候变化及影响因素比较研究

利用蒙古国中部6个气象站1940~2004年和中国内蒙古自治区中部6个气象站1951~2004年的温度和降水资料,对两地的气候变化及其影响因素作了对比研究。结果表明:20世纪90年代与60年代相比,中国内蒙古6站平均升温1.35℃,蒙古国6站上升1.13℃,2000~2004年与60年代相比:中国内蒙古6站上升1.89℃,蒙古国则为1.37℃,中国内蒙古6站的升温速率高于蒙古国6站。对温度变化趋势作突变性检验,结果表明:温度发生突变时间是纬度较高地区早于纬度较低的地区,大城市早于中小城镇,城市化对温度变化影响比较明显。相对于温度变化,降水变化没有显著性的突变,但有周期变化,中国内蒙古降水变化有2.8年周期,蒙古国有4年、8年的周期,这可能因为中国内蒙古降水水汽主要来源于太平洋,而蒙古国降水的水汽主要来源于北冰洋。     

亚热带山地丘陵区植被NPP时空变化及其与气候因子的关系————以湖南省为例

以湖南省为研究区,采用250 m×250 m空间分辨率的MODIS-NDVI数据,结合相应时间段的气象数据,使用改进的CASA模型,模拟并分析该区域2000-2013年间的植被NPP的时空变化特征,并借助统计分析方法对不同土地覆盖类型中植被NPP的变化趋势及其显著性,NPP与气候因子的相关性进行量化分析.结果表明:① 该区域的净初级生产量年际变化特征明显,年净初级生产量分布在41.62~125.40 Tg C/yr之间,平均值为86.34 Tg C/yr,总体来看,14年间湖南省植被净初级生产量呈波动减少趋势,年际减少趋势为2.70 Tg C/yr;② NPP空间分布差异较大,基本特点是西高东低,南高北低,从西南向东北呈逐渐递减趋势,其中,各植被分区的NPP有明显差异;③ 2000-2013年,湖南省植被NPP呈极显著增加(slope >0,p < 0.01),显著增加(slope > 0,0.01 ≤ p < 0.05),无明显变化(p ≥ 0.05),极显著减少(slope < 0,p < 0.01)和显著减少(slope < 0,0.01 ≤ p < 0.05)的区域分别占总面积的比例为5.40%,2.02%,61.64%,16.79%和14.15%.植被NPP变化趋势总体上显示为减少的趋势,而不同土地覆盖类型的植被NPP变化趋势及显著性存在较大差异,其中草地的NPP变化趋势最为显著,接着依次是森林,其他土地,建设用地和农田;④ 分析不同土地覆盖类型的植被NPP对气候因子的响应,发现NPP与降水量之间的相关关系强于其与温度的相关关系.     

中国东南部植被NPP的时空格局变化及其与气候的关系研究

基于2001~2010年MOD17A3年均NPP数据和气象站点气温、降水资料,利用GIS空间分析技术和数理统计方法研究中国东南部植被NPP的时空格局、动态变化及与气候要素的关系。结果表明,中国东南部植被年均NPP总体上呈现从南到北、由东至西逐渐减少的分布,不同植被类型的NPP存在明显差异,以常绿阔叶林最高,落叶针叶林最低。2001~2010年间,植被NPP整体上略有减少。空间上植被NPP在南部地区明显减少,而在北部地区明显增加。植被NPP与降水和气温的相关性均表现出明显的地域差异。     

Modeling net primary productivity of the terrestrial ecosystem in China from 1961 to 2005简

Net primary productivity （NPP） is the structure and function of the ecosystem. NPP can most important index that represents the be simulated by dynamic global vegetation models （DGVM）, which are designed to represent vegetation dynamics relative to environ- mental change. This study simulated the NPP of China＇s ecosystems based on the DGVM Integrated Biosphere Simulator （IBIS） with data on climate, soil, and topography. The appli- cability of IBIS in the NPP simulation of China＇s terrestrial ecosystems was verified first. Comparison with other relevant studies indicates that the range and mean value of simula- tions are generally within the limits of observations; the overall pattern and total annual NPP are close to the simulations conducted with other models. The simulations are also close to the NPP estimations based on remote sensing. Validation proved that IBIS can be utilized in the large-scale simulation of NPP in China＇s natural ecosystem. We then simulated NPP with climate change data from 1961 to 2005, when warming was particularly striking. The following are the results of the simulation. （1） Total NPP varied from 3.61 GtC/yr to 4.24 GtC/yr in the past 45 years and exhibited minimal significant linear increase or decrease. （2） Regional differences in the increase or decrease in NPP were large but exhibited an insignificant overall linear trend. NPP declined in most parts of eastern and central China, especially in the Loess Plateau. （3） Similar to the fluctuation law of annual NPP, seasonal NPP also displayed an insignificant increase or decrease; the trend line was within the general level. （4） The re- gional differences in seasonal NPP changes were large. NPP declined in spring, summer, and autumn in the Loess Plateau but increased in most parts of the Tibetan Plateau.     

过去300年大兴安岭北部气候变化特征（英文）

The Greater Khingan Mountains(Daxinganling) are China's important ecological protective screen and also the region most sensitive to climate changes. To gain an in-depth understanding and reveal the climate change characteristic in this high-latitude, cold and data-insufficient region is of great importance to maintaining ecological safety and corresponding to global climate changes. In this article, the annual average temperature, precipitation and sunshine duration series were firstly constructed using tree-ring data and the meteorological observation data. Then, using the climate tendency rate method, moving-t-testing method, Yamamoto method and wavelet analysis method, we have investigated the climate changes in the region during the past 307 years. Results indicate that, since 1707, the annual average temperature increased significantly, the precipitation increased slightly and the sunshine duration decreased, with the tendency rates of 0.06℃/10 a, 0.79 mm/10 a and –5.15 h/10 a, respectively(P≤0.01). Since the 21 st century, the period with the greatest increase of the annual average temperature(also with the greatest increase of precipitation) corresponds to the period with greatest decrease of sunshine duration. Three sudden changes of the annual average temperature and sunshine duration occurred in this period while two sudden changes of precipitation occurred. The strong sudden-change years of precipitation and sunshine duration are basically consistent with the sudden-change years of annual average temperature, suggesting that in the mid-1860 s, the climatic sudden change or transition really existed in this region. In the time domain, the climatic series of this region exhibit obvious local variation characteristics. The annual average temperature and sunshine duration exhibit the periodic variations of 25 years while the precipitation exhibits a periodic variation of 20 years. Based on these periodic characteristics, one can infer that in the period from 2013 to 2030, the temperature will be at a high-temperature stage, the precipitation will be at an abundant-precipitation stage and the sunshine duration will be at an less-sunshine stage. In terms of spatial distribution, the leading distribution type of the annual average temperature in this region shows integrity, i.e., it is easily higher or lower in the whole region; and the second distribution type is more(or less) in the southwest parts and less(or more) in the northeast parts. Precipitation and sunshine duration exhibit complex spatial distribution and include fourspatial distribution types. The present study can provide scientific basis for the security investigation of homeland, ecological and water resources as well as economic development programming in China's northern borders.     

全球气候变化背景下基于土地利用的人类活动对城市热环境变化归因分析——以京津冀城市群为例

近年来全球气候变化已经影响到人类生活的所有地区,气候系统变化的规模和现状是数千年来前所未有的。与此同时,中国城镇化进程显著加快,尤其以城市建设用地扩张主导的土地城镇化最为突出,导致城市热环境脆弱性加剧。已有研究探索了特定类型土地利用变化对于城市热环境的影响,但忽视了全球气候变化背景下自然气候和人类活动共同作用城市热环境变化的双重过程。因此,本研究提出一种基于土地利用类型的城市热环境变化贡献度算法,旨在厘清自然气候（表征为土地利用平均温度变化）和人类活动（表征为土地利用类型转变）对于区域热环境变化的单独贡献。本研究使用中分辨率成像光谱仪（Moderate-Resolution Imaging Spectroradiometer,MODIS）地表温度及发射率数据,定量计算2005—2020年四季和昼夜京津冀城市群各城市土地利用类型平均温度和面积变化对于城市热环境变化的分别贡献。该算法计算各城市四季和昼夜地表温度变化与MODIS LST产品误差在1 K以内。2005—2020年各城市地表平均温度大多数呈增长态势,其中冬季白天增温幅度最高。耕地、城市建设用地和农村居民点对城市热环境变化的贡献度较其他土地利用类型突出。京津冀城市群中各城市人类活动对城市热环境变化的单位贡献强度远高于自然气候（4.03~648.07倍）,而人类活动的贡献总量（-0.25~0.92 K）低于自然气候（-2.40~6.50 K）。研究结果对于京津冀城市群空间协同发展和适应及减缓气候变化等具有重要的科学意义和实践价值。     

三江平原气温降水变化分析——以建三江垦区为例

气温及降水与人类生产生活密切联系,其变化必然会对生态系统和社会经济等产生重大影响。利用三江平原建三江垦区15个农场气象站1965～2002年气温和降水资料,运用气候趋势系数和一元回归分析法进行气候变化分析。结果表明:近40年来本区气温呈显著上升趋势,平均气温以0.50℃/10a幅度升高,不同季节平均气温均呈上升趋势,且冬季增幅最大,达0.82℃/10a。气温升高存在显著的区域差异,最大的增温中心位于南部边缘,气温倾向率大于0.60℃/10a。降水趋势性变化不显著,但仍呈弱减少趋势,年降水量倾向率为-1.90mm/10a,四季降水量以秋季减少最为显著。在此基础上进行气候突变分析,结果表明气温突变出现在1987年,降水突变出现在1980年和1997年,但降水突变不明显。研究三江平原建三江垦区的气候变化对于保障区域粮食安全具有重要的指导意义。     

1961–2005年中国陆地生态系统净初级生产力模拟（英文）

Net primary productivity(NPP) is the most important index that represents the structure and function of the ecosystem.NPP can be simulated by dynamic global vegetation models(DGVM),which are designed to represent vegetation dynamics relative to environmental change.This study simulated the NPP of China's ecosystems based on the DGVM Integrated Biosphere Simulator(IBIS) with data on climate,soil,and topography.The applicability of IBIS in the NPP simulation of China's terrestrial ecosystems was verified first.Comparison with other relevant studies indicates that the range and mean value of simulations are generally within the limits of observations;the overall pattern and total annual NPP are close to the simulations conducted with other models.The simulations are also close to the NPP estimations based on remote sensing.Validation proved that IBIS can be utilized in the large-scale simulation of NPP in China's natural ecosystem.We then simulated NPP with climate change data from 1961 to 2005,when warming was particularly striking.The following are the results of the simulation.(1) Total NPP varied from 3.61 GtC/yr to 4.24 GtC/yr in the past 45 years and exhibited minimal significant linear increase or decrease.(2) Regional differences in the increase or decrease in NPP were large but exhibited an insignificant overall linear trend.NPP declined in most parts of eastern and central China,especially in the Loess Plateau.(3) Similar to the fluctuation law of annual NPP,seasonal NPP also displayed an insignificant increase or decrease;the trend line was within the general level.(4) The regional differences in seasonal NPP changes were large.NPP declined in spring,summer,and autumn in the Loess Plateau but increased in most parts of the Tibetan Plateau.