Discussion on the ecological theory and technological approaches of ecosystem quality improvement and stability enhancement.

Improving ecosystem quality and stability is one of the urgent tasks of national ecological environment construction. However, the ecological theory of ecosystem quality and stability has not been well clarified. Based on the summary of influencing factors and interaction between ecosystem quality and stability, we discussed the ecolo-gical theory on the evolution of ecosystem quality and stability from the perspectives of self-organization of biological agglomeration and structure nesting, correlation of ecological elements and coupling of ecological processes, ecosystem integrity and function emergence, ecological service spillover and efficiency tradeoff, synergy and interactions between resource supply capacity and environmental suitability, as well as interactions between spontaneous change and human activities.

Eddy covariance-based differences in net ecosystem productivity values and spatial patterns between naturally regenerating forests and planted forests in China.

Net ecosystem productivity (NEP), the difference between gross primary productivity (GPP) and ecosystem respiration (ER), is the basis of forest carbon sinks. Revealing NEP differences between naturally regenerating forests (NF) and planted forests (PF) can benefit for making carbon neutrality strategies. Based on 35 eddy covariance measurements in China, we analyzed NEP differences in values and spatial patterns between NF and PF.

Mapping Chinese annual gross primary productivity with eddy covariance measurements and machine learning.

Annual gross primary productivity (AGPP) is the basis for grain production and terrestrial carbon sequestration. Mapping regional AGPP from site measurements provides methodological support for analysing AGPP spatiotemporal variations thereby ensures regional food security and mitigates climate change. Based on 641 site-year eddy covariance measuring AGPP from China, we built an AGPP mapping scheme based on its formation and selected the optimal mapping way, which was conducted through analysing the predicting performances of divergent mapping tools, variable combinations, and mapping approaches in predicting observed AGPP variations.

[Ecological economics foundation research on ecological values, ecological asset management, and value realization: Scientific concepts, basic theories, and realization paths].

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.

[Discussion on the ecological theory and assessment methods of ecosystem quality and its evolution].

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.

[Theories of ecosystem vulnerability, adaptability and catastrophe based on the mechanisms of ecological succession.].

With the increases in the breadth and depth of the impacts of climate change, the theories of ecosystem vulnerability, adaptability and catastrophe have gradually been widely applied in the field of ecology to explore and evaluate the sensitivity, vulnerability and adaptation of various ecosystems to climatic change. Based on such research, we can seek better ways to cope with the far-reaching impact of climatic change on ecosystems, and serve the sustainable management of national ecosystems and the construction of ecological security. Although a lot of achievements have been made to distinguish the sensitive regions responding to climatic change and potential tipping points in certain ecosystems, there are still multiple understandings and interpretations of these concepts in the academic community.

[Research advances in critical transition and its ecological mechanisms of terrestrial ecosystems.].

With the exacerbating disturbances of climate changes and human activities to terrestrial ecosystems, more and more studies realize that ecosystems are at the risk of shifts without warning in structural and functional states and recovery from perturbations require more time. Developing an early warning model to identify critical transition and understanding its ecological mechanism of typical ecosystems have become hotspot in ecological researches. At present, based on theoretical and experimental researches across multiple spatiotemporal scales, a variety of theoretical frameworks and indicators of early warning signals (EWSs) were proposed to signal terrestrial ecosystem critical transition.

[Evaluation theory and method of regional resources and environmental carrying capacity.].

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.

[Discussion on the scientific concepts of regional resources and environmental carrying capacity and its ecological basis.].

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.

Effects of ecosystem types on the spatial variations in annual gross primary productivity over terrestrial ecosystems of China.

Annual gross primary productivity (AGPP) serves as the basis for forming biomass and carbon sinks. Analysing the effects of ecosystem types on AGPP spatial variations would be beneficial for clarifying the spatial variability in AGPP, which would serve ecological management practices such as ensuring regional food security. Based on published eddy covariance measurements in China, we collected AGPP data from 128 ecosystems and analysed the effects of ecosystem types on the spatial variations in AGPP to reveal the AGPP spatial variability and its influencing factors over terrestrial ecosystems of China.

[A process-based model and simulation system of dynamic change and spatial variation in large-scale terrestrial ecosystems].

More attention has been paid to the monitoring, assessment, prediction, early warning and sustainable management of regional ecological environment and the changes of ecosystem state in recent years. It is an important scientific and technological task to develop quantitative methods and numerical simulation techniques for ecosystem modelling, and to construct the continental scale numerical simulator with the characteristics of multi-process coupling, multi-technology integration, and multi-objective application for stimulating research on ecosystem and global change and its resources, environment and disaster effects, based on the in-depth understanding of the components, processes, functions, patterns, and their interaction mechanism of terrestrial ecosystem. Here, we reviewed the current status and future direction of terrestrial ecosystem models, and discussed the conceptual framework of developing the simulation system of dynamic change and spatial variation in large-scale terrestrial ecosystems and its resource and environment effect, as well as basic issues on the function orientation and structure design of the simulation system, which would provide reference for constructing Chinese terrestrial ecosystem numerical simulator.

[Multi-disciplinary knowledge integration and its technical approaches in the integrated ecology of macroecosystem science].

The development of contemporary macroecosystem sciences requires to comprehensively understand the process mechanism and model mechanism of large-scale macroecosystem structure and function, spatial variation, and dynamic evolution, to realize quantitative simulation, scientific assessment, prediction and early warning of ecosystem change and its impacts on human well-being, and to serve the utilization, protection, regulation, and management of ecosystems. Therefore, a new research field of large-scale integrated ecology of macroecosystem science (IEMES) is emerging. Based on the systematic analysis of the basic theories, approaches and key technologies of integrated ecology of macroecosystem science, the following basic understandings have been formed: 1) IEMES takes macroecosystem at regional, continental, and global scales as the research object, and adopts the methods and technologies of multidisciplinary knowledge integration.

Manipulative experiments networks on response and adaptation of terrestrial ecosystems to environmental changes: Building the research methods and technology system.

The feedback relationship between organisms or ecosystems and environment has been a key issue in ecological research. Manipulative experiments with changing biological or environmental factors and large-scale field experiment networks were regarded as effective approaches to understand and accurately quantify the process and mechanisms underlying ecosystem response and adaptation to environmental changes. In recent years, a few networks have been developed, including large-scale networks of field physics simulation experiment (.

[A coordinated three-dimensional network for observing large-scale terrestrial ecosystem status changes and the consequences on resources and environment].

Co-driven by environmental change and human activity, global ecosystem has been experiencing rapid changes, with cascading effects on resources and environment. The changes of ecosystem status and its spatiotemporal evolution drivers, and the related resource and environmental effects have been recognized as the long standing topics of large-scale terrestrial ecosystem science. The coordinated observation networks distributed across different continents and the globe provide the valuable tools for observing and evaluating ecosystem state change, for revealing and elaborating mechanisms underlying ecosystem response, for cognizing and understanding ecosystem evolution, and for predicting and early-warning of ecosystem change.

[Discussion on the multi-disciplinary dimensional basic problems and methodology systems of macroecosystem science research.].

The urgent requirement of human society to solve major resource and environmental pro-blems at the regional and global scales promotes the rises of macroecosystem science (MES) and the multidisciplinary fusions of natural science and humanities. Furthermore, it facilitates the innovation of macroecosystem scientific theory, as well as the development of continental and global scale knowledge fusion methodology and key technology. With the aim to serve the construction and deve-lopment of continental and global scale knowledge fusion methodological system for the changes of ecosystem status and resource environmental effect studies, we systematically elaborated the multi-disciplinary dimensional basic scientific problems, logic relationships and frontiers in the macroecosystem science, discussed the ideology and content of constructing the continental and global scale research methodological system, proposed to develop the networked observation-networked experiment-numerical simulation-knowledge fusion four-in-one infrastructures.

[Technical approach and strategic plan for large-scale ecological and environmental gover-nance and national ecological security pattern construction.].

Terrestrial ecosystems are the core components of the biosphere, supporting human life, production and social and economic activities. With the development of human civilization and the progress of science and technology, the continued expanding resources utilization in terms of scale and intensity has caused environmental problems, including global climate change, biodiversity loss, environmental pollution, resource depletion and ecosystem degradation, which threaten the sustainable development of our society. The public expects ecological research providing scientific theories and systematic solutions for the utilization and protection of ecosystems at the continental and global scale, and the maintenance of sustainable development of human society as well.

Thinking on large-scale terrestrial ecosystem management and its theoretical fundament and practice.

Ecosystem management at large scales is one of the core solutions to solve current global challenges of environmental and resources problem, mitigate climate change, govern ecosystems and environments regionally and achieve sustainable development. It is also a hotspot in the research and practice of conservation of global natural resources and ecosystems. Based on recalling and synthesizing of several large international actions on ecosystem management in the past two decades, this article rethought the concept of ecosystem management and its application from the perspective of discipline development of ecosystem management, theoretical fundaments and practices.

Discussion on the theoretical basis and technical system of large-scale terrestrial ecosystem science research.

Large-scale terrestrial ecosystem science research becomes an important research field with the promotion of meeting the scientific demand of biodiversity conservation, global climate change mitigation, regional eco-environment governance, and social sustainable development. It is developing rapidly under the guidance of China's ecological civilization construction strategy. Here, we systematically discussed the missions, theoretical foundation and methodology of large-scale terrestrial ecosystem science research and proposed a new theoretical foundation, conceptual system and logical framework for macroecosystem science research on the basis of macrosystem ecology theory.

[Discussion on the scientific concept of ecology and its evolution and the contemporary ecologi-cal discipline system].

Ecology is not only a branch of biology, but also an important part of environmental science and earth system science. The results of ecological studies can be directly applied in biodiversity conservation of plant, animal and microbe, biological resource utilization and biological industry management, and other fields. The concept of ecosystem extends classic ecology or basic ecology research to a new stage of ecosystem ecology or ecosystem science, which has laid a theoretical foundation for the scientific research of ecological environment at the global and continental scales, and has promoted the integration of biology, geography, and environmental science, and cross disciplinary of the natural sciences, humanities, and social economic sciences.

[Regulation effects of temperate broadleaved Korean pine forest on temperature and humidity in Changbai Mountain, China.].

Forests can improve climate and regulate micro-environment. The study of forest micro-climate is of great significance to reveal forest ecosystem function and evaluate the benefits of forest ecological environment. With broadleaved Korean pine forest in Changbai Mountain as test material, the diurnal and seasonal variations of the mean, maximum and minimum temperature, relative humidity and surface soil temperature were analyzed based on the meteorological data of flux tower in the forest and nearby meteorological station in the open land from 2003 to 2014.

[Comparative Study of SWAT and DNDC Applied to N Leach and Export from Subtropical Watershed].

In this study, N export from Xiangxi River Basin in subtropical watershed was measured by long-term monitoring, N loss in the basin was simulated by DNDC and SWAT models in order to provide a scientific basis for the establishment of nitrogen circulation model in subtropical watershed. The results showed that N loss with runoff was well simulated by DNDC and SWAT. The key parameters of DNDC were precipitation, slope and amount of N fertilization, while the key parameters of SWAT were GW_DELAY, CANMX, ALPHA_BF and ESCO.

[Nitrogen Release from Sediment Under Dry and Rainy Season Alternation and Its Contribution to N Export from Xiangxi Watershed in Jiangxi Province].

In this study, N export from Xiangxi River Basin in Qianyanzhou station was measured by long-term monitoring, and simulation study on N. release law from the sediment in watershed was carried out based on orthogonal experiment, and at last the contributions of N release from sediment to N transport from watershed under dry and rainy season alternation were estimated. The results showed that the maximum of TN release rate was 36 mg x (m2 x d)(-1) in stable status, which decreased with increasing time; the impact of the three controlling factors on the N release followed the order of temperature > disturbance > pH, and the effect of temperature and pH on N release from the sediment was significant when disturbance was considered as the error term; TN release rate increased with increase of temperature, and acidic and alkaline conditions could also promote N release from sediment, wherein the effect of acidic conditions on N release was stronger; the changes of TN and available N content in sediment were 414.

Exogenous N addition enhances the responses of gross primary productivity to individual precipitation events in a temperate grassland.

Predicted future shifts in the magnitude and frequency (larger but fewer) of precipitation events and enhanced nitrogen (N) deposition may interact to affect grassland productivity, but the effects of N enrichment on the productivity response to individual precipitation events remain unclear. In this study, we quantified the effects of N addition on the response patterns of gross primary productivity (GPP) to individual precipitation events of different sizes (Psize) in a temperate grassland in China. The results showed that N enrichment significantly increased the time-integrated amount of GPP in response to an individual precipitation event (GPPtotal), and the N-induced stimulation of GPP increased with increasing Psize.

[Chemical Characteristics of Atmospheric Wet Deposition in Winter and Its Forestry Canopy Interception Mechanism in Red Soil Hilly Area].

In order to disclose the interception mechanism of forestry canopy to atmospheric wet deposition, the concentrations of nutrients (C, N, P, S) and trace elements (K, Ca, Na, Mg, Al, Fe, Mn, Zn) in wet deposition and through fall in winter were monitored in Subtropical Qiananzhou basin. The results showed that the wet deposition in this area was mainly acid deposition, the pH of which ranged from 3.49 to 7.