The potential for an old-growth forest to store carbon in the topsoil:A case study at Sasso Fratino,Italy

There is considerable interest devoted to oldgrowth forests and their capacity to store carbon(C)in biomass and soil.Inventories of C stocks in old-growth forests are carried out worldwide,although there is a lack of information on their actual potential for C sequestration.To further understand this,soil organic carbon(SOC)was measured in one of Italy's best-preserved old-growth forests,the Sasso Fratino Integral Nature Reserve.This reserve is on the World Heritage List along with other ancient beech forests of Europe,and it is virtually untouched due to the steepness of the terrain,even before legal constraints were imposed.Although the sandstone-derived soils are often shallow,they are rich in organic matter.However,no quantification had been carried out.By systematically sampling the topsoil across the forest,we accurately determined the average amount of SOC(62.0±16.9 Mg ha^(–1))and nitrogen(4.0±1.2 Mg ha^(–1))in the top 20 cm.Using the CENTURY model,future dynamics of SOC stocks were predicted to 2050 according to two climate scenarios,A1F1 and B2,the first of high concern and the second more optimistic.The model projected an increase of 0.2 and 0.3 Mg ha^(–1)a^(–1)by 2030 under the A1F1 and B2 scenarios,respectively,suggesting that the topsoil in old-growth forests does not reach equilibrium but continues accumulating SOC.However,from 2030 to 2050,a decline in SOC accumulation is predicted,indicating SOC net loss at high altitudes under the worst-case scenario.This study confirms that soils in oldgrowth forests play a significant role in carbon sequestration.It also suggests that climate change may affect the potential of these forests to store SOC not only in the long term but also in the coming years.

Great Changes Unseen for a Century in American Politics and the 2020 US Presidential Election

American politics is currently undergoing great changes unseen in a century,which has been predominately manifested in the following hree aspects:first,the rampant COVID-19 pandemic has caused the US tosuffer its worst economic recession since the Great Depression in 1929;second,social division and political polarization are besetting the US as evidenced in its wide partisan divide between the supporters of its two major parties on a range of critical issues;and third,the US is caught in anational identity crisis,while China's rise is believed to intensify such a crisis.These three factors are bound to exert great impacts on the 2020 presidential election of the United States:the COVID-19 pandemic will have certain influence on voter turnout and the approval rating of the two parties;in the context of the aforementioned serious social divide and highly polarized political landscape,the basic constituencies of the two parties are likely to show an extraordinary degree of party loyalty,which could result in the possibility that a few voters in a handful of key states will determine the results of the election;and as China's peaceful rise ismistaken as a serious threat to the national identity of the US.China will be one of the key topics in the coming US presidential election,hence further worsening the relations between China and the United States.

The COVID-19 Pandemic and Changes Unseen in a Century

The COVID-19 pandemic can be compared to a world war that makes the existing international order unsustainable.The pandemic is interacting with global changes unseen in a century and exerting major impacts on international politics,world economy,major-country relations,the geostrategic landscape,global governance,and development models.In the next three to five years,the international landscape will be a chaotic situation,highlighting not poles but competing states and transformation,thus making it more difficult for major countries to cooperate while medium-sized and small states have to huddle for warmth and seek a way out within their respective regions.Although further observation is required during the ongoing pandemic and worldwide economic recession,some major trends in the world have emerged.A restart to China's international relations is called for.

New Trends in International Energy Security in the Context of Profound Changes Unseen in a Century

Major changes such as the pandemic, games among great powers, and the Ukraine crisis alongside scientific and technological progress, economic transformation, social change, and cultural development have led to new features and trends in the international energy field. Historic fluctuations in international energy prices and adjustments in energy relations have taken place in the past two years. The energy system has fallen into disorder and discomfort;volatility in the energy market has triggered a strong domino effect, and major countries have taken unprecedented measures to address it. These changes have pushed international energy politics to a new development track. In a certain period of time in the future, the political and security aspects of energy will once again come to the fore. The long-term nature and complexity of the energy transition have become more obvious. In international energy politics, turbulence and uncertainty will be the new normal. A new binary opposition may emerge in the international energy landscape as well, with constant changes taking place in the connotation and extension of energy security. Academic and strategic circles should think deeply about how to dialectically discuss the relation between energy transition and the major changes of a scale unseen in a century, energy transition and energy security, and geopolitics and energy politics, among others, and consider the integration of development and security and the realization of common energy security as important principles for operating and developing energy strategies and promoting global energy governance.

Spatial patterns and driving forces of land use change in China during the early 21st century

Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science （LCS） in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21 st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the ＂Grain for Green＂ policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of ＂Western Development＂, ＂Revitalization of Northeast＂, coupled with rapidly economic development during this period.

Progress in China's climate change study in the 20th century

Studies on the 20th century climate change in China have revealed that under the background of global warming over the past century, climate in China has also experienced significant change with mean annual temperature increased by about 0.5 oC. More reliable results for the latter part of the 20th century indicate that the largest warming occurred in Northwest China, North China and Northeast China, and the warming in winter is most significant. Although no obvious increase or decrease trends were detected for mean precipitation over China in the past half century, regional differences are very distinct. In the middle and lower reaches of the Yangtze River, precipitation increased, while that in the Yellow River Basin markedly decreased. Studies suggest that climate change in China seems to be related not only with the internal factors such as ENSO, PDO, and the others, but also with the anthropogenic effects such as greenhouse gas emissions, and land use. The future climate change studies in China seem to be important in narrowing understanding the nature of China's climate change and its main causes, since it is significant for projection and for impact assessment of climate change in the future.

Precipitation Changes in Wet and Dry Seasons over the 20th Century Simulated by Two Versions of the FGOALS Model

Seasonal precipitation changes over the globe during the 20th century simulated by two versions of the Flexible Global Ocean-Atmosphere-Land System （FGOALS） model are assessed. The two model versions differ in terms of their AGCM component, but the remaining parts of the system are almost identical. Both models reasonably reproduce the mean-state features of the timings of the wet and dry seasons and related precipitation amounts, with pattern correlation coefficients of 0.65-0.84 with observations. Globally averaged seasonal precipitation changes are analyzed. The results show that wet sea- sons get wetter and the annual range （precipitation difference between wet and dry seasons） increases during the 20th century in the two models, with positive trends covering most parts of the globe, which is consistent with observations. However, both models show a moistening dry season, which is opposite to observations. Analysis of the globally averaged moisture budget in the historical climate simulations of the two models shows little change in the horizontal moisture advection in both the wet and dry seasons. The globally averaged seasonal precipitation changes are mainly dominated by the changes in evaporation and vertical moisture advection. Evaporation and vertical moisture advection combine to make wet seasons wetter and enhance the annual range. In the dry season, the opposite change of evaporation and vertical moisture advection leads to an insignificant change in precipitation. Vertical moisture advection is the most important term that determines the changes in precipitation, wherein the thermodynamic component is dominant and the dynamic component tends to offset the effect of the thermodynamic component.

Changes of Air–sea Coupling in the North Atlantic over the 20th Century

Changes of air–sea coupling in the North Atlantic Ocean over the 20 th century are investigated using reanalysis data,climate model simulations, and observational data. It is found that the ocean-to-atmosphere feedback over the North Atlantic is significantly intensified in the second half of the 20 th century. This coupled feedback is characterized by the association between the summer North Atlantic Horseshoe（NAH） SST anomalies and the following winter North Atlantic Oscillation（NAO）. The intensification is likely associated with the enhancement of the North Atlantic storm tracks as well as the NAH SST anomalies. Our study also reveals that most IPCC AR4 climate models fail to capture the observed NAO/NAH coupled feedback.

Spatio-temporal Changes and Associated Uncertainties of CENTURYmodelled SOC for Chinese Upland Soils, 1980-2010

Detailed information on the spatio-temporal changes of cropland soil organic carbon(SOC) can significantly contribute to the improvement of soil fertility and mitigate climate change. Nonetheless, information and knowledge on the national scale spatio-temporal changes and the corresponding uncertainties of SOC in Chinese upland soils remain limited. The CENTURY model was used to estimate the SOC storages and their changes in Chinese uplands from 1980 to 2010. With the Monte Carlo method, the uncertainties of CENTURY-modelled SOC dynamics associated with the spatial heterogeneous model inputs were quantified. Results revealed that the SOC storage in Chinese uplands increased from 3.03(1.59 to 4.78) Pg C in 1980 to 3.40(2.39 to 4.62) Pg C in 2010. Increment of SOC storage during this period was 370 Tg C, with an uncertainty interval of –440 to 1110 Tg C. The regional disparities of SOC changes reached a significant level, with considerable SOC accumulation in the Huang-Huai-Hai Plain of China and SOC loss in the northeastern China. The SOC lost from Meadow soils, Black soils and Chernozems was most severe, whilst SOC accumulation in Fluvo-aquic soils, Cinnamon soils and Purplish soils was most significant. In modelling large-scale SOC dynamics, the initial soil properties were major sources of uncertainty. Hence, more detailed information concerning the soil properties must be collected. The SOC stock of Chinese uplands in 2010 was still relatively low, manifesting that recommended agricultural management practices in conjunction with effectively economic and policy incentives to farmers for soil fertility improvement were indispensable for future carbon sequestration in these regions.

How Managers Can Manage Change and Stability to Deliver Better Service to Customers in the 21st Century

In an ever-changing world at present, many enterprises and organizations are put under the great pressure of tremendous opportunities and challenges arising from globalization, technological innovation, intense competition and also a highly competitive market."The whole business environment becomes more competitive, dynamic, and complex in 21st century."(Olsen, West and Ching Yick Tse 2008) Hussey (2005) also has the view that the organization' external and internal environment has changed ever more turbulently in past few decades.[1] The frequency of changes has become faster and the period of stability has tended to be much shorter. Therefore change management skills become more and more important for managers.(Hussey, 2005) Dawson also has the same point of view. He says "the large-scale change really occurs and the changes were rarely so rapid and unpredictable"(Dawson, 1994). This situation may continue in to the next century (Hussey, 2005) which means that managers need to deeply understand how to manage both external and internal changes.[2] Hussey also mentions some important factors that may influence external environment changes including competition globally;customers service expectation increase, fast development of technology,[3] and changes in government regulations (Hussey, 2005).

基于CENTURY模型的乌审召滩地草场ANPP及对气候变化的响应

利用CENTURY模型对乌审召滩地草场1963─2010年地上净初级生产力(ANPP)动态进行了模拟研究,并将ANPP的模拟值与26个气象因子进行了相关性分析,以探讨气象因子对草地生产力的影响,为草地合理管理和持续利用提供理论支持。结果表明,CENRUTY模型能够比较准确地模拟这类草原的季节动态和年际变化。在过去的48年间,乌审召滩地草场生长季温度呈升高趋势,降水呈减少趋势,ANPP呈下降趋势,且ANPP下降幅度较降水量明显,其中每10年ANPP下降8.10 g·m^(-2)、降水量下降4.60 mm。利用气象观测资料模拟获得的年ANPP随气温和降水的变化而呈现出明显的变化规律,生长季内地上生物量对降水和温度的季节性分布也非常敏感。模型订正与验证结果显示,观测值与模拟值的相关系数变化范围为0.41~0.62,误差平方根值(RMSE)变化范围为57.29~87.17 g·m^(-2),平均绝对百分比误差(MAPD)变化范围为33.76%~63.39%。相关分析表明,不同时段降水量对ANPP均有明显影响,其中生长季、冬季和春季降水量对ANPP影响非常显著。极端高温对ANPP的负面影响非常显著,低温、蒸发、日照时数、风速以及年最大积雪深度等其他气象因子对ANPP的影响不显著。研究区ANPP呈下降趋势是降水量减少和极端高温事件频发共同作用的必然结果。

On Latin American Protests in 2019

A large-scale wave of mass protests broke out in fifteen Latin American countries during 2019.Some protests led to the resignation of the president and the collapse of the government.Others caused social unrest and bloody conflicts.Some protests led to a national"curfew",and the government was forced to cancel major international conferences.For a time,over ten countries were engaged in turbulent and chaotic activities.Accordingly,the 2019 Latin American protests were also dubbed"Latin America’s Turmoil"by the international media.The scale,scope and impact of the protests have been rarely seen over the last forty years.They constituted part of the global chaos of 2019.The cause was not only the anxious response of the Latin American countries facing global changes not seen for a century,but also a concentrated outbreak of political,economic and social contradictions that has been accumulating in certain Latin American countries over a long period of time.Facing unprecedented global change over a century,the Latin American countries will be able to usher in the"Latin American Spring"only if they carry out profound reform with great courage,and achieve significant progress in their political systems,economic structures,and social security systems.

从Travel到Tourism——论19世纪英国旅游概念的变易

19世纪初期“tourism”见诸英语,后又取代“travel”的主流地位,标志着英国古典旅行观向现代旅游观的转变。“tourism”概念由于适应了工业文明时代旅游大众化、市场化、产业化的需要,因而从市井俚语上升为20世纪西方旅游理论的主流概念。厘清它与汉语中“旅游”概念之间深刻的文化差异,是中国旅游学界应对西方旅游理论的一大关键。

基于CENTURY模型的甘肃草地固碳潜力对气候因子和二氧化碳浓度升高的响应

气候变化对草地碳循环的影响日益严峻,研究运用本地参数化后的CENTURY模型和1989—2018年甘肃省77个站点的气象观测数据,选用生产指标净生态系统生产力(NEP)和生态指标土壤有机碳(SOC)为主要研究对象,检验模型适用性、利用统计分析方法和ArcGIS软件分析30年气候数据时空分布格局和气候变化对草地碳循环的影响机制。同时根据IPCC第五次评估报告对气候变化的预测设计了3种气候情境,预估未来气候变化条件下,NEP和SOC的时空变化特征,并与实际情景进行对比分析。结果表明,过去30年年际NEP和SOC整体呈现波动下降的趋势,NEP以每年14.23 gC·m^(-2)·a^(-1)的速度减小,1989—2018年的NEP均大于零,表现为碳汇;SOC以每年55.41 gC·m^(-2)的速度减小,正在逐年流失。温度、降水是影响NEP和SOC的主要因素,NEP与温度显著正相关,与降水有较弱的正相关,SOC与温度显著负相关,与降水有较弱的负相关。在未来气候情景中,气温升高和降水波动增大是导致NEP和SOC变化的主要原因,且CO_(2)浓度加倍时,单独的气温升高会导致NEP显著增加,SOC显著降低;单独的降水波动增大对NEP和SOC的影响不大。在甘肃北方干旱地区,降水成为主要限制因子。

Centennial Evolution of the CPC’s National Security Thought

Born at a time of domestic turmoil and foreign aggression,the Communist Party of China(CPC)has an ingrained understanding of and has always attached great importance to national security.Undergoing different stages of national development from"standing up"to"growing rich"and to"becoming strong,"the CPC has been constantly adjusting its visions and strategies on national security in light of changes in the international situation.Such visions and strategies will surely continue to be enriched and improved in the great endeavors of building socialism with Chinese characteristics.With the proposal of the"ten upholds,"the theoretical system of national security with Chinese characteristics for the new era has taken shape,which will be underpinned by a holistic approach to national security.Thus,a historic leap in the century-old construction of the CPC’s national security theory system has been achieved.This paper aims to explore the ideological context of the formation and development of a holistic approach to national security from the centennial evolution of the CPC’s national security thought,comprehend the theoretical guiding role of the CPC’s national security thought from China’s historic achievements over the past century,and grasp the historic significance and values of upholding and developing a holistic approach to national security from the new historic juncture in China’s development and its historical responsibilities in the context of great changes unseen in a century.

The Sino-U.S. Frictions and Global Security under the Backdrop of Changes Unseen in a Century

Since the first half of 2019,the Sino-U.S.trade frictions have become more and more intense since the United States has announced higher and higher tariffs,having attracted a lot of attention and resources given by academia,diplomacy and business circles at home and abroad.

International Taxation and the BRITACOM:A Study from the Perspective of“Profound Changes Unseen in a Century”

The world is undergoing"profound changes unseen in a century",which is crucial for current development of international taxation.The trends of"world multi-polarization,economic globalization,IT application and cultural diversity"are surging forward.New driving forces are replacing the old ones.Balance among different countries is also changing rapidly.A global governance system is thus reshaping.Based on all these changes,this paper analyzes their impacts on international taxation,and particularly the Belt and Road Initiative Tax Administration Cooperation Mechanism(BRITACOM).

The Profound Changes Unseen in a Century: The Perspective of Overlapping Effect of Technological Revolution Cycle and Political & Economic Thought Cycle

The waves of technological revolution can lead to great differences in the economic and social structures of countries and have a destructive impact. The choice of political and economic thoughts can amplify or inhibit such differentiation and impact. Over the past 100 years, humankind has undergone three technological revolutions, and the mainstream political and economic thoughts have experienced a cycle from classical liberalism to various types of anti-liberalism and finally to neoliberalism. In the two liberal periods, the overlap of liberalism and a technological revolution caused sharp contradictions between the rich and the poor, leading to profound economic adjustment and great political and social turmoil worldwide. In the non-liberal period, however, the overlapping effects were relatively mild. Currently, the world is facing similar trends and risks as during 1914-1940. Whether humankind will repeat the same mistakes merits attention and vigilance. This study argues that it is necessary to oppose unilateralism, uphold multilateralism, and advance globalization and free trade under the concept of collaborative development and shared prosperity, as well as explore comprehensive and sustainable development. These are of great significance for human society to prevent risks, obtain advantages and avoid disadvantages, and maintain world peace and development.

百年变局之变、历史启示及中国的战略选择

当今世界处于百年未有之大变局,“东升西降”的历史大势与国际体系加速转型相互叠加演进,而中国也正处于实现第二个百年奋斗目标、实现中华民族伟大复兴的关键时期。客观冷静地厘清世界百年变局的内涵要义,是准确把握当前国际形势风云变幻的逻辑起点。中国未来发展,需要顺应时代特征、国际格局、大国关系、全球治理、世界矛盾的新变化进行战略运筹谋划。对比中国和其他国家百年发展走过的道路与取得的经验,有助于更加坚定中国式现代化发展的基本遵循和道路方向,进一步增强在新的动荡变革期把握战略机遇、驾驭战略风险的能力。