Erratum: Ecosystem quality-based management and the development of a new eco-friendly economy.

[This corrects the article DOI: 10.1016/j.xinn.2023.100491.].

The carbon budget of China: 1980-2021.

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.

Ecosystem carbon use efficiency in ecologically vulnerable areas in China: Variation and influencing factors.

Ecologically vulnerable areas (EVAs) are regions with ecosystems that are fragile and vulnerable to degradation under external disturbances, e.g., environmental changes and human activities. A comprehensive understanding of the climate change characteristics of EVAs in China is of great guiding significance for ecological protection and economic development. The ecosystem carbon use efficiency (CUEe) can be defined as the ratio of the net ecosystem productivity (NEP) to gross primary productivity (GPP), one of the most important ecological indicators of ecosystems, representing the capacity for carbon transfer from the atmosphere to a potential ecosystem carbon sink. Understanding the variation in the CUEe and its controlling factors is paramount for regional carbon budget evaluation. Although many CUEe studies have been performed, the spatial variation characteristics and influencing factors of the CUEe are still unclear, especially in EVAs in China. In this study, we synthesized 55 field measurements (3 forestland sites, 37 grassland sites, 6 cropland sites, 9 wetland sites) of the CUEe to examine its variation and influencing factors in EVAs in China. The results showed that the CUEe in EVAs in China ranged from -0.39 to 0.67 with a mean value of 0.20. There were no significant differences in the CUEe among different vegetation types, but there were significant differences in CUEe among the different EVAs (agro-pastoral ecotones < Tibetan Plateau < arid and semiarid areas < Loess Plateau). The CUEe first decreased and then increased with increasing mean annual temperature (MAT), soil pH and soil organic carbon (SOC) and decreased with increasing mean annual precipitation (MAP). The most important factors affecting the CUEe were biotic factors (NEP, GPP, and leaf area index (LAI)). Biotic factors directly affected the CUEe, while climate (MAT and MAP) and soil factors (soil pH and SOC) exerted indirect effects. The results illustrated the comprehensive effect of environmental factors and ecosystem attributes on CUEe variation, which is of great value for the evaluation of regional ecosystem functions.

[Ecological economics foundation research on ecological values, ecological asset management, and value realization: Scientific concepts, basic theories, and realization paths]. / è‡ªç„¶ç”Ÿæ€ä»·å€¼ã€ç”Ÿæ€èµ„äº§ç®¡ç†åŠä»·å€¼å®žçŽ°çš„ç”Ÿæ€ç»æµŽå­¦åŸºç¡€ç ”ç©¶­­ç§‘学概念、基础理论及实现途径.

Ecosystems provide various environmental conditions and natural resources for life, production, and human livelihoods. Ecosystem management based on natural laws is the basic way for human society to recognize the value of nature and ecosystems, protect and utilize the natural environment and resources, create and accumulate ecological assets, and sustainably develop. Taking that as one of the core concepts, regional ecological economics or economic ecology is becoming a frontier in scientific research to evaluate the Anthropocene earth system and sustainable development. From the perspective of macro-ecosystem science, based on the multi-functionality and multi-values of ecosystems, this study expounded the concepts of natural ecological value, ecological assets, ecological products, and some related phrases, analyzed the processes and principles of formation and change of ecological assets, production and consumption of ecological products, ecological investment, and profit and loss of ecological assets based on integrated ecology, sociology, and economics, proposed paths of regional ecological asset management and ecological value realization. It would provide theoretical and methodological references for the evaluation of regional ecosystem value and ecological assets, and the development of ecological industries and ecological value realization systems.

[Discussion on the ecological theory and assessment methods of ecosystem quality and its evolution]. / ç”Ÿæ€ç³»ç»Ÿè´¨é‡åŠå ¶çŠ¶æ€æ¼”å˜çš„ç”Ÿæ€å­¦ç†è®ºå’Œè¯„ä¼°æ–¹æ³•ä¹‹æŽ¢ç´¢.

Ecological civilization construction and ecological environment governance are basic tasks of state gover-nance in China. China has clearly put forward the goal of improving ecosystem quality and stability. However, there are no consensus on the scientific concept of ecosystem quality and the assessment methods of ecosystem quality evolution, which has puzzled the academic community. Based on the summarization of the scientific concept of ecosystem quality and its evolution, we discussed the concept of ecosystem quality and its ecological theory basis by referencing the concept of production quality, quality management and quality assessment of material production. The scientific connotation of ecosystem quality and its evolution was discussed from the perspectives of ecosystem natural attribute-social attribute-economic attribute and the relationships between them, the cascade relations of ecosystem component-structure-process-function-service-efficacy, the feedback of factor-system-environment, and the logic relation of state ecosystem fluctuation-quantity variation-quality alternation. We proposed perspectives and approaches of multi-objective assessment of ecosystem quality alternation from the aspects of natural resource environment system, typical ecosystem, regional macro-ecosystem, and ecological engineering efficacy.

[Discussion on the scientific concepts of regional resources and environmental carrying capacity and its ecological basis.] / åŒºåŸŸèµ„æºçŽ¯å¢ƒæ‰¿è½½åŠ›ç§‘å­¦æ¦‚å¿µåŠå ¶ç”Ÿæ€å­¦åŸºç¡€çš„è®¨è®º.

The carrying capacity of resources and environment is an essential concept in ecology, the theoretical and practical research of which has become an important basis for measuring regional sustainable development. However, the scientific connection between the ecological foundation and the carrying capacity of resources and environment is still unclear. Moreover, it remains unknown which ecological theories played a supporting role in the development of the resources and environment carrying capacity, which makes the scientific concept of carrying capacity very vague. Based on the discussion of the scientific concepts and development of the carrying capacity of resources and environmen, we systematically discussed the basic concepts, such as the niche volume that organisms can occupy, the ecological threshold of ecosystems to withstand environmental stress, the potential resource capacity (supply capacity) of sustainable supply such as climate, water and nutrition, and the environmental capacity of buffering and purifying pollutants. Furthermore, from the biophysical point perspective of foundation pressure bearing capacity, spatial capacity carrying capacity and ecological threshold carrying capacity, the scientific concepts of Natural Resources Supply Carrying Capacity (NRSCC), Nature Environment Carrying Capacity (NECC), Carrying Capacity of Biological Population Development (CCBPD), Carrying Capacity of Social and Economic Development (CCSED) and Carrying Capacity of Environmental Stress in Ecosystems (CCESE) were defined. Finally, three basic issues of ecology were discussed in detail, including the theory of population growth and the ecological capacity of the ecosystem, the theory of ecosystem multi-functionality and resource and environmental effects, and the theory of alternative stable states, self-adaptability, and self-organization. Based on exploring the theory and method of regional resource environmental assessment, this study would provide theoretical basis for regional resource environment utilization, protection and social and economic sustainable development.

[Evaluation theory and method of regional resources and environmental carrying capacity.] / 区域资源环境承载力的评价理论及方法讨论.

Our understanding of resources and environmental carrying capacity is deepened with the comprehensive effects of human needs and external stress. When human survival and development mainly depend on the supply of local resources and environmental conditions, the resources and environmental carrying capacity is largely controled by the dominant limiting factors. With sustainable development and environmental protection, the resources and environmental carrying capacity has gradually changed from supply restriction to demand support. There is an expression of capacity, threshold, intensity, and ability to characterize the resources and environmental carrying capacity. The impact of climate change and human activities on the resource and environmental system is increasing, altering resources and environmental carrying capacity. At present, the interrelationship and internal mechanism among resource and environmental carrying capacity, ecosystem vulnerability, and climate change risk are still unclear, which restricts the further development of theory and method. We preliminarily summarized and discussed the basic theory and method system of the research on carrying capacity of regional resources and environment. Furthermore, we advocated to develop the cascade relations of "carrying capacity of biological population development-carrying capacity of environmental stress in ecosystems-natural resources supply carrying capacity-natural environment carrying capacity-carrying capacity of social and economic development". Moreover, the calculation method and conceptual model of multi-dimensional resource and environmental carrying capacity were put forward under each concept framework. This study provided new ideas for the research on the method of resources and environment carrying capacity.

Development of atmospheric acid deposition in China from the 1990s to the 2010s.

Atmospheric acid deposition is a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to become more severe with the country's economic development and increasing consumption of fossil fuels in recent decades. We explored the spatiotemporal variations of acid deposition (wet acid deposition) and its influencing factors by collecting nationwide data on pH and concentrations of sulfate (SO42-) and nitrate (NO3-) in precipitation between 1980 and 2014 in China. Our results showed that average precipitation pH values were 4.59 and 4.70 in the 1990s and 2010s, respectively, suggesting that precipitation acid deposition in China has not seriously worsened. Average SO42- deposition declined from 40.54 to 34.87 kg S ha-1 yr-1 but average NO3- deposition increased from 4.44 to 7.73 kg N ha-1 yr-1. Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of controlling the pollutant emissions; but the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Furthermore, we found significant positive correlations between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a relatively comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and control pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions.

Regional representativeness assessment and improvement of eddy flux observations in China.

Both the amounts of data describing the site-scale carbon flux at a high temporal and spatial resolution collected in China and the number of eddy covariance flux towers have been increasing during the last decade. To correctly upscale these fluxes to the regional and global level, the representativeness of the current network of flux towers must be known. The present study quantifies the representativeness of the flux network for the regional carbon exchange. This analysis combined the total solar radiation, air temperature, vapor pressure and the enhanced vegetation index to indicate the environmental characteristics of each 1-km pixel cell and flux tower. Next, the Euclidean distance from each pixel to the tower was calculated to determine the representativeness of the existing flux towers. To improve the regional representativeness, additional tower locations were pinpointed by identifying and clustering the underrepresented areas. The existing network of flux towers performed well in representing the environmental conditions of the middle and the northeastern portions of China. The well-represented areas covered 60.9% of the total areas. The towers in croplands and grasslands represented the vegetation types well, but the wetlands and barelands were poorly represented. The representativeness of the flux network increased with the addition of nine towers located in forests, grasslands, wetlands and barelands. The representativeness of 27.5% of the land areas improved. In addition, the well-represented areas were enlarged by 15.2%. Substantial gains in representation were achieved by adding new towers on the Tibet Plateau. The representativeness of the northwest and southwest was improved less significantly, suggesting that more towers are required to capture certain ecosystem behaviors.

Groundwater nitrogen pollution and assessment of its health risks: a case study of a typical village in rural-urban continuum, China.

Protecting groundwater from nitrogen contamination is an important public-health concern and a major national environmental issue in China. In this study, we monitored water quality in 29 wells from 2009 to 2010 in a village in Shanghai city, whick belong to typical rural-urban continuum in China. The total N and NO(3)-N exhibited seasonal changes, and there were large fluctuations in NH(4)-N in residential areas, but without significant seasonal patterns. NO(2)-N in the water was not stable, but was present at high levels. Total N and NO(3)-N were significantly lower in residential areas than in agricultural areas. The groundwater quality in most wells belonged to Class III and IV in the Chinese water standard, which defines water that is unsuitable for human consumption. Our health risk assessments showed that NO(3)-N posed the greatest carcinogenic risk, with risk values ranging from 19×10(-6) to 80×10(-6), which accounted for more than 90% of the total risk in the study area.

[Effects of CO2 storage flux on carbon budget of forest ecosystem].

Carbon dioxide (CO2) storage flux in the air space below measurement height of eddy covariance is very important to correctly evaluate net ecosystem exchange of CO2 (NEE) between forest ecosystem and atmosphere. This study analyzed the dynamic variation of CO2 storage flux and its effects on the carbon budget of a temperate broad-leaved Korean pine mixed forest at Changbai Mountains, based on the eddy covariance flux data and the vertical profile of CO2 concentration data. The CO2 storage flux in this forest ecosystem had typical diurnal variation, with the maximum variation appeared during the transition from stable atmospheric layer to unstable atmospheric layer. The CO2 storage flux calculated by the change in CO2 concentration throughout a vertical profile was not significantly different from that calculated by the change in CO2 concentration at the measurement height of eddy covariance. The NEE of this forest ecosystem was underestimated by 25% and 19% at night and at daytime, respectively, without calculating the CO2 storage flux at half-hour scale, and was underestimated by 10% and 25% at daily scale and annual scale, respectively. Without calculating the CO2 storage flux in this forest ecosystem, the parameters of Michaelis-Menten equation and Lloyd-Taylor equation were underestimated, and the ecosystem apparent quantum yield (alpha) and the ecosystem respiration rate (Rref) at the reference temperature were mostly affected. The gross primary productivity (GPP) and ecosystem respiration (Re) of this forest ecosystem were underestimated about 20% without calculating the CO2 storage flux at half-hour, daily scale, and annual scale.

[Carbon budget of ecosystem in Changbai Mountain Natural Reserve].

The study used EPPML, a biological geochemistry cycle model that was built, to simulate the carbon budget for ecosystems in Changbai Mountain Natural Reserve. The results indicated that the annual net primary productivity [NPP (carbon)] of the natural reserve was 1.332 x 10(6) t.a-1. The annual NPP of mixed broad-leaved and Korean pine forest and spruce-fir forest were maximal, 0.540 x 10(6) t.a-1 and 0.428 x 10(6) t.a-1 respectively. The area and productivity of the two stands were maximal in Changbai Mountain, therefore, the simulating productivity of the two stands most greatly affect carbon cycle and carbon budget of the natural reserve, and the veracity of the former decides the security of the latter. To sum up, not only did the simulations accord with routines in the relative comparisons between different vegetation belts and climate belts in the whole natural reserve, but also was exact in the absolute comparisons with very disperse data from field survey. Vegetations in the natural reserve had evident carbon sink functions, mainly exhibiting in the increasing of carbon, about 1.058 x 10(6) t.a-1. The annual carbon of mixed broad-leaved and Korean pine forest increased greatest (0.452 x 10(6) t.a-1), secondly spruce-fir forest (0.339 x 10(6) t.a-1). The two stands played crucial roles in the carbon sink for Changbai Mountain, others being Changbai larch forest, broad-leaved forest, meadow, shrub, alpine tundra, subalpine Betula ermanii forest and alpine grass. In 1995, the decomposing carbon of soil organic matter was 0.169 x 10(6) t.a-1 higher than the littering carbon in the natural reserve. There was accumulation of organic matter in the meadow soil and shrub soil. The decomposition and accumulation of soil organic matter was in the nearly balancing condition in the alpine tundra soil and alpine grass soil. The decomposition of organic matter was as one and a half time or double as litterfall in the arbor forest soil.