• Energy Research

Forestation is important for sequestering atmospheric carbon, and it is a cost-effective and nature-based solution (NBS) for mitigating global climate change. Here, under the assumption of forestation in the potential plantable lands, we used the forest carbon sequestration (FCS) model and field survey involving 3365 forest plots to assess the carbon sequestration rate (CSR) of Chinese existing and new forestation forests from 2010 to 2060 under three forestation and three climate scenarios. Without considering the influence of extreme events and human disturbance, the estimated average CSR in Chinese forests was 0.358 ± 0.016 Pg C a-1, with partitioning to biomass (0.211 ± 0.016 Pg C a-1) and soil (0.147 ± 0.005 Pg C a-1), respectively. The existing forests account for approximately 93.5% of the CSR, which will peak near 2035, and decreasing trend was present overall after 2035. After 2035, effective tending management is required to maintain the high CSR level, such as selective cutting, thinning, and approximate disturbance. However, new forestation from 2015 in the potential plantable lands would play a minimal role in additional CSR increases. In China, the CSR is generally higher in the Northeast, Southwest, and Central-South, and lower in the Northwest. Considering the potential losses through deforestation and logging, it is realistically estimated that CSR in Chinese forests would remain in the range of 0.161-0.358 Pg C a-1 from 2010 to 2060. Overall, forests have the potential to offset 14.1% of the national anthropogenic carbon emissions in China over the period of 2010-2060, significantly contributing to the carbon neutrality target of 2060 with the implementation of effective management strategies for existing forests and expansion of forestation.

The boreal forests, identified as a critical “tipping element” of the Earth's climate system, play a critical role in the global carbon budget. Recent findings have suggested that terrestrial carbon sinks in northern high-latitude regions are weakening, but there has been little observational evidence to support the idea of a reduction of carbon sinks in northern terrestrial ecosystems. Here, we estimated changes in the biomass carbon sink of natural stands throughout Canada's boreal forests using data from long-term forest permanent sampling plots. We found that in recent decades, the rate of biomass change decreased significantly in western Canada (Alberta, Saskatchewan, and Manitoba), but there was no significant trend for eastern Canada (Ontario and Quebec). Our results revealed that recent climate change, and especially drought-induced water stress, is the dominant cause of the observed reduction in the biomass carbon sink, suggesting that western Canada's boreal forests may become net carbon sources if the climate change–induced droughts continue to intensify.

Forests play an important role in acting as a carbon sink of terrestrial ecosystem. Although global forests have huge carbon carrying capacity (CCC) and carbon sequestration potential (CSP), there were few quantification reports on Chinese forests. We collected and compiled a forest biomass dataset of China, a total of 5841 sites, based on forest inventory and literature search results. From the dataset we extracted 338 sites with forests aged over 80 years, a threshold for defining mature forest, to establish the mature forest biomass dataset. After analyzing the spatial pattern of the carbon density of Chinese mature forests and its controlling factors, we used carbon density of mature forests as the reference level, and conservatively estimated the CCC of the forests in China by interpolation methods of Regression Kriging, Inverse Distance Weighted and Partial Thin Plate Smoothing Spline. Combining with the sixth National Forest Resources Inventory, we also estimated the forest CSP. The results revealed positive relationships between carbon density of mature forests and temperature, precipitation and stand age, and the horizontal and elevational patterns of carbon density of mature forests can be well predicted by temperature and precipitation. The total CCC and CSP of the existing forests are 19.87 and 13.86 Pg C, respectively. Subtropical forests would have more CCC and CSP than other biomes. Consequently, relying on forests to uptake carbon by decreasing disturbance on forests would be an alternative approach for mitigating greenhouse gas concentration effects besides afforestation and reforestation.

Abstract Bacteria are one of the most abundant and diverse groups of micro‐organisms and mediate many critical terrestrial ecosystem processes. Despite the crucial ecological role of bacteria, our understanding of their large‐scale biogeography patterns across forests, and the processes that determine these patterns lags significantly behind that of macroorganisms. Here, we evaluated the geographic distributions of bacterial diversity and their driving factors across nine latitudinal forests along a 3,700‐km north–south transect in eastern China, using high‐throughput 16S rRNA gene sequencing. Four of 32 phyla detected were dominant: Acidobacteria, Actinobacteria, Alphaproteobacteria and Chloroflexi (relative abundance > 5%). Significant increases in bacterial richness and phylogenetic diversity were observed for temperate forests compared with subtropical or tropical forests. The soil organic matter (SOM) mineralisation rate (SOMmin, an index of SOM availability) explained the largest significant variations in bacterial richness. Variation partition analysis revealed that the bacterial community structure was closely correlated with environmental variables and geographic distance, which together explained 80.5% of community variation. Among all environmental factors, climatic features (MAT and MAP) were the best predictors of the bacterial community structure, whereas soil pH and SOMmin emerged as the most important edaphic drivers of the bacterial community structure. Plant functional traits (community weighted means of litter N content) and diversity resulted in weak but significant correlations with the bacterial community structure. Our findings provide new evidence of bacterial biogeography patterns from tropical to cold temperate forests. Additionally, the results indicated a close linkage among soil bacterial diversity, climate and SOM decomposition, which is critical for predicting continental‐scale responses under future climate change scenarios and promoting sustainable forest ecosystem services. A plain language summary is available for this article.

Aims Recent studies revealed convergent temperature sensitivity of ecosystem respiration (Re) within aquatic ecosystems and between terrestrial and aquatic ecosystems. We do not know yet whether various terrestrial ecosystems have consistent or divergent temperature sensitivity. Here, we synthesized 163 eddy covariance flux sites across the world and examined the global variation of the apparent activation energy (Ea), which characterizes the apparent temperature sensitivity of and its interannual variability (IAV) as well as their controlling factors. Methods We used carbon fluxes and meteorological data across FLUXNET sites to calculate mean annual temperature, temperature range, precipitation, global radiation, potential radiation, gross primary productivity and Re by averaging the daily values over the years in each site. Furthermore, we analyzed the sites with >8 years data to examine the IAV of Ea and calculated the standard deviation of Ea across years at each site to characterize IAV. Important Findings The results showed a widely global variation of Ea, with significantly lower values in the tropical and subtropical areas than in temperate and boreal areas, and significantly higher values in grasslands and wetlands than that in deciduous broadleaf forests and evergreen forests. Globally, spatial variations of Ea were explained by changes in temperature and an index of water availability with differing contribution of each explaining variable among climate zones and biomes. IAV and the corresponding coefficient of variation of Ea decreased with increasing latitude, but increased with radiation and corresponding mean annual temperature. The revealed patterns in the spatial and temporal variations of Ea and its controlling factors indicate divergent temperature sensitivity of R-e, which could help to improve our predictive understanding of R-e in response to climate change.

The U.S.-China EcoPartnership for Environmental Sustainability (USCEES), one of 30 EcoPartnerships, was established within the U.S.-China Strategic Economic Dialogue framework in May 2011 by a joint agreement between the U.S. Department of State and China's National Development and Reform Commission. The USCEES has the goal of fostering bi-national research innovation, communication, and entrepreneurship to address the interconnected challenges of environmental, social, and economic sustainability. Research and education programs within the USCEES are focused on understanding current and past degradation of natural resources, investigating the drivers, impacts, and mitigation of global climate change, and assessing options for sustainable use of natural resources. Although both the U.S. and China have embraced a future based on science, technology, and innovation, our bi-national framework acknowledges that these two nations have vastly different cultural, political, and demographic legacies that could pose distinct challenges to uniform solutions or mandated collaborative networks. The peer-to-peer connections that drive the research component of the USCEES program are promoted and initiated from the ground up; they are based on the voluntary participation of scientists and engineers who are fascinated by the intellectual challenge of solving complex problems of inherent interest to them. Herein, we present highlights of USCEES activities that describe our efforts to discover, incubate, and nurture U.S.-China research collaborations to meet our collective goals. We discuss our pilot programs that are designed to highlight university facilities, resources, and technologies for tech transfer and licensing with an environmental solutions-oriented direction. Additionally, programs to promote cross-EcoPartnership collaborations are discussed.

En tant que l'un des plus grands émetteurs de gaz à effet de serre au monde, la Chine s'est fixé l'objectif ambitieux d'atteindre le pic de carbone et la neutralité carbone. Par conséquent, il est crucial de quantifier l'ampleur et la tendance des sources et des puits de dioxyde de carbone atmosphérique (CO2), et de suivre les progrès de la Chine vers ces objectifs. À l'aide d'ensembles de données et de modèles de pointe, cette étude a estimé de manière exhaustive les émissions anthropiques de CO2 provenant de l'énergie, des processus industriels et de l'utilisation des produits, ainsi que des déchets, des sources naturelles et des puits de CO2 pour toute la Chine au cours de la période 1980-2021. Pour reconnaître les différences entre les différentes méthodes d'estimation des émissions de gaz à effet de serre, les estimations sont comparées aux inventaires nationaux de gaz à effet de serre (INGES) de la Chine pour 1994, 2005, 2010, 2012 et 2014. Les émissions anthropiques de CO2 en Chine ont été multipliées par 7,39 entre 1980 et 2021, passant à 12,77 Gt CO2 a-1. Tout en bénéficiant de projets écologiques (par exemple, le Three Norths Shelter Forest System Project), le puits de carbone terrestre en Chine a atteint 1,65 Gt de CO2 a-1 en moyenne entre 2010 et 2021, soit près de 15,81 fois celui du puits de carbone des années 1980. En moyenne, les écosystèmes terrestres de la Chine ont compensé 14,69 % ± 2,49 % des émissions anthropiques de CO2 jusqu'en 2010-2021. Deux régions administratives de niveau provincial de la Chine, Xizang et Qinghai, ont atteint la neutralité carbone selon nos estimations, mais près de la moitié des régions administratives de la Chine ont des compensations de puits de carbone terrestres de moins de 10% des émissions anthropiques de CO2. Cette étude a indiqué un niveau élevé de cohérence entre les NGHGI et divers ensembles de données utilisés pour estimer les émissions de CO2 d'origine fossile, mais a révélé des différences notables pour les puits de carbone terrestres. Les estimations futures des puits de carbone terrestres des NGHGI doivent être vérifiées de toute urgence avec des modèles basés sur les processus qui intègrent les processus complets du cycle du carbone. Como uno de los mayores emisores de gases de efecto invernadero del mundo, China se ha fijado el ambicioso objetivo de alcanzar el pico de carbono y la neutralidad de carbono. Por lo tanto, es crucial cuantificar la magnitud y la tendencia de las fuentes y sumideros de dióxido de carbono atmosférico (CO2), y monitorear el progreso de China hacia estos objetivos. Utilizando conjuntos de datos y modelos de vanguardia, este estudio estimó exhaustivamente las emisiones antropogénicas de CO2 de la energía, los procesos industriales y el uso de productos, y los desechos junto con las fuentes naturales y los sumideros de CO2 para toda China durante 1980-2021. Para reconocer las diferencias entre los diversos métodos de estimación de las emisiones de efecto invernadero, las estimaciones se comparan con los Inventarios Nacionales de Gases de Efecto Invernadero (GEI) de China para 1994, 2005, 2010, 2012 y 2014. Las emisiones antropogénicas de CO2 en China han aumentado 7,39 veces desde 1980 a 12,77 Gt CO2 a-1 en 2021. Si bien se beneficia de proyectos ecológicos (por ejemplo, Three Norths Shelter Forest System Project), el sumidero de carbono terrestre en China ha alcanzado un promedio de 1.65 Gt CO2 a-1 entre 2010 y 2021, que es casi 15.81 veces mayor que el sumidero de carbono en la década de 1980. En promedio, los ecosistemas terrestres de China compensaron el 14,69% ± 2,49% de las emisiones antropogénicas de CO2 entre 2010 y 2021. Según nuestras estimaciones, dos regiones administrativas a nivel provincial de China, Xizang y Qinghai, han logrado la neutralidad de carbono, pero casi la mitad de las regiones administrativas de China tienen compensaciones de sumideros de carbono terrestres de menos del 10% de las emisiones antropogénicas de CO2. Este estudio indicó un alto nivel de consistencia entre los INGH y varios conjuntos de datos utilizados para estimar las emisiones fósiles de CO2, pero encontró diferencias notables para los sumideros de carbono terrestres. Las estimaciones futuras de los sumideros de carbono terrestre de los GEI deben verificarse urgentemente con modelos basados en procesos que integren los procesos integrales del ciclo del carbono. باعتبارها واحدة من أكبر الدول المسببة لانبعاثات غازات الدفيئة في العالم، وضعت الصين لنفسها هدفًا طموحًا يتمثل في تحقيق ذروة الكربون وحياد الكربون. لذلك، من الأهمية بمكان تحديد حجم واتجاه مصادر ومصارف ثاني أكسيد الكربون في الغلاف الجوي (CO2)، ومراقبة تقدم الصين نحو هذه الأهداف. باستخدام أحدث مجموعات البيانات والنماذج، قدرت هذه الدراسة بشكل شامل انبعاثات ثاني أكسيد الكربون البشرية المنشأ من الطاقة والعمليات الصناعية واستخدام المنتجات والنفايات جنبًا إلى جنب مع المصادر الطبيعية ومصارف ثاني أكسيد الكربون في جميع أنحاء الصين خلال الفترة 1980-2021. للتعرف على الاختلافات بين الطرق المختلفة لتقدير انبعاثات غازات الدفيئة، تتم مقارنة التقديرات بقوائم الجرد الوطنية لغازات الدفيئة في الصين للأعوام 1994 و 2005 و 2010 و 2012 و 2014. زادت انبعاثات ثاني أكسيد الكربون البشرية المنشأ في الصين بمقدار 7.39 مرة من عام 1980 إلى 12.77 جيجا طن من ثاني أكسيد الكربون في عام 2021. مع الاستفادة من المشاريع البيئية (على سبيل المثال، مشروع نظام غابات المأوى في الشمال)، بلغ بالوعة الكربون في الصين 1.65 جيجا طن من ثاني أكسيد الكربون في المتوسط خلال الفترة 2010-2021، وهو ما يقرب من 15.81 ضعف بالوعة الكربون في الثمانينيات. في المتوسط، عوضت النظم الإيكولوجية الأرضية في الصين 14.69 ٪ ± 2.49 ٪ من انبعاثات ثاني أكسيد الكربون البشرية المنشأ خلال الفترة 2010-2021. حققت منطقتان إداريتان على مستوى المقاطعة في الصين، شيزانغ وتشينغهاي، حيادية الكربون وفقًا لتقديراتنا، ولكن ما يقرب من نصف المناطق الإدارية في الصين لديها تعويضات بالوعة الكربون الأرضية أقل من 10 ٪ من انبعاثات ثاني أكسيد الكربون البشرية المنشأ. أشارت هذه الدراسة إلى وجود مستوى عالٍ من الاتساق بين مؤشرات الغازات الدفيئة الوطنية ومجموعات البيانات المختلفة المستخدمة لتقدير انبعاثات ثاني أكسيد الكربون الأحفوري، ولكنها وجدت اختلافات ملحوظة في بالوعات الكربون الأرضية. هناك حاجة ماسة إلى التحقق من التقديرات المستقبلية لأحواض الكربون الأرضية الخاصة بالمصارف الصحية الوطنية من خلال النماذج القائمة على العمليات التي تدمج عمليات دورة الكربون الشاملة. As one of the world's largest emitters of greenhouse gases, China has set itself the ambitious goal of achieving carbon peaking and carbon neutrality. Therefore, it is crucial to quantify the magnitude and trend of sources and sinks of atmospheric carbon dioxide (CO2), and to monitor China's progress toward these goals. Using state-of-the-art datasets and models, this study comprehensively estimated the anthropogenic CO2 emissions from energy, industrial processes and product use, and waste along with natural sources and sinks of CO2 for all of China during 1980-2021. To recognize the differences among various methods of estimating greenhouse emissions, the estimates are compared with China's National Greenhouse Gas Inventories (NGHGIs) for 1994, 2005, 2010, 2012, and 2014. Anthropogenic CO2 emissions in China have increased by 7.39 times from 1980 to 12.77 Gt CO2 a-1 in 2021. While benefiting from ecological projects (e.g., Three Norths Shelter Forest System Project), the land carbon sink in China has reached 1.65 Gt CO2 a-1 averaged through 2010-2021, which is almost 15.81 times that of the carbon sink in the 1980s. On average, China's terrestrial ecosystems offset 14.69% ± 2.49% of anthropogenic CO2 emissions through 2010-2021. Two provincial-level administrative regions of China, Xizang and Qinghai, have achieved carbon neutrality according to our estimates, but nearly half of the administrative regions of China have terrestrial carbon sink offsets of less than 10% of anthropogenic CO2 emissions. This study indicated a high level of consistency between NGHGIs and various datasets used for estimating fossil CO2 emissions, but found notable differences for land carbon sinks. Future estimates of the terrestrial carbon sinks of NGHGIs urgently need to be verified with process-based models which integrate the comprehensive carbon cycle processes.

AbstractThere is growing evidence that land‐use management practices such as livestock grazing can strongly impact the local diversity, functioning, and stability of grassland communities. However, whether these impacts depend on environmental condition and propagate to larger spatial scales remains unclear. Using an 8‐year grassland exclosure experiment conducted at nine sites in the Tibetan Plateau covering a large precipitation gradient, we found that herbivore exclusion increased the temporal stability of alpine grassland biomass production at both the local and larger (site) spatial scales. Higher local community stability was attributed to greater stability of dominant species, whereas higher stability at the larger scale was linked to higher spatial asynchrony of productivity among local communities. Additionally, sites with higher mean annual precipitation had lower dominant species stability and lower grassland stability at both the spatial scales considered. Our study provides novel evidence that livestock grazing can impair grassland stability across spatial scales and climatic gradients.