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Reservoirs are a rapidly increasing water body providing water supply, irrigation, and many other benefits for human societies globally. However, due to changes in hydrological conditions, building reservoirs tends to bring adverse effects such as eutrophication and phytoplankton blooms, reducing the ecosystem service values. This study focuses on using the empirical dynamic modeling (EDM), an emerging approach for nonlinear analysis, to investigate the nonlinear causal relationship of water level fluctuation (WLF) on phytoplankton biomass and then develop a quantitative model guiding effective phytoplankton blooms controlling based on water level regulations in reservoirs. Specifically, with 9-year continued daily observed data in the Three Gorges Reservoir, we examined the causal effects of different WLF parameters on the dynamics of phytoplankton blooms for the first time. We found that the water level change in the past 24 h (ΔWL) has the strongest causal effect on the daily dynamics of phytoplankton biomass among all WLF parameters (ΔWL, |ΔWL|, and the water level), with a time lag of 2 days. Moreover, EDM revealed a nonlinear relationship between ΔWL and daily dynamics of phytoplankton biomass and achieved a successful prediction for the chlorophyll a concentration 2-day ahead. Further scenario analyses found that both the rise and fall of water level will significantly reduce the chlorophyll a concentration when phytoplankton blooms occur. Nevertheless, on the whole, the rising water level has a more substantial effect on phytoplankton blooms than falling the water level. This result reveals that regulating ΔWL is a simple and effective approach in controlling phytoplankton blooms in reservoirs. Our study reported the nonlinear causal effect of ΔWL on the dynamics of chlorophyll a and provided a quantitative approach guiding effective phytoplankton blooms controlling based on the water level regulation, which might have a broad application in algal blooms controlling in reservoirs and similar waterbodies.

In this study, spatio-temporal characteristics of particulate matter (PMx; x = 2.5 and 10) mass concentrations and aerosol optical properties were analyzed over the water source area of the South–North Water Diversion Central Line. For this purpose, PM2.5 and PM10 mass concentrations were collected at the Taocha(TC) station from October 2018 to September 2019, and aerosol optical depth (AOD) was obtained from the Cloud-Aerosol LiDAR and Infrared Pathfinder Satellite Observation (CALIPSO) satellite from 2007 to 2019. The monthly, seasonal, and daily statistical analyses and related comparisons were conducted in the present study. The results showed that the PM10 concentrations meet China’s ambient air secondary quality standard (100 μg/m3 annual mean), whereas PM2.5 did not meet China’s ambient air secondary quality standard (35 μg/m3 annual mean) at the TC station, no obvious seasonal and diurnal variations are observed, and these particulates are caused by local emissions and outside sources. A significant positive correlation of PM2.5 and PM10 was observed with relative humidity and temperature, whereas no relationship was found with wind direction. The results also showed low (~0.1) AOD in spring, autumn, and winter, whereas slightly higher AOD (~0.3) was observed in summer. This may be caused by straw burning from long-distance transportation. This study may provide new data support for comprehensive ecological measures such as strengthening the ecological environment and water quality protection in the Middle Route Project of the South–North Water Diversion.

Under the global warming, the significant changes in atmospheric water cycle lead to drying in arid region, which is strengthening the effect of aerosol on Fog-Haze generation and accelerating the emergence of infectious diseases. However, the production process of the Fog-Haze is lack of quantitative description based on atmospheric water cycle. In this paper, we modeled the process of Fog-Haze generation, evolution and disappearance fundamentally and theoretically. The budget functions for water vapor and aerosol were coupled by the physical and chemical interaction between water vapor and aerosol. The obtained results may provide new insights on the control of Fog-Haze and the related infectious diseases induced by Fog-Haze.

China has been undergoing rapid economic growth since its reform and opening-up at the expense of resource depletion and environmental pollution. We estimated the monetary costs of resource depletion and environmental pollution in China over the past 14 recent years by establishing integrated mathematical models with System for Integrated Environmental and Economic Accounting (SEEA) framework. Results showed four points. Firstly, the total temporal costs of natural resource depletion and environmental pollution witnessed an inverted ‘U’ shape pattern with the turning point in 2012. The relationship between cost of mineral resource depletion, as well as water pollution cost, and per capita GDP were found to follow the Inverted-U shape environmental Kuznets curve (EKC). Secondly, the average annual share of natural resources of the total costs was more than 80%, indicating that the rapid economic growth of China is highly dependent on resource depletion. Thirdly, Although China still has the highest worldwide in its total energy consumption and CO2 emission, China's struggles with adjustment of industrial & energy consumption structure, and pollution controls have resulted in a general temporal decline of the share of resource and environmental costs to China's GDP. The green GDP of China is growing at an average rate of 14.76%. Finally, although in the process of manufactured goods for the whole world, China has reduced environmental pollution and left it at home as much as possible. Driving forces behind the progress in green GDP of China were analyzed by using Differences-in-Differences method and Spearman rank correlation analysis.

The complexity of economic development and humanitarian crises means that energy science and technology should be involved in actions that address almost every major challenges of ecosystem health and sustainability. Energy is the engine of the world economy and the key to ecosystems’ functioning, which also has a great impact on global warming. The energy crisis, environmental pollution, overuse of natural resources, water supply shortages, global climate disruption, and deteriorating ecosystems are major challenges to address in order to achieve the United Nations Sustainable Development Goals (SDGs). In light of the frontiers in energy sciences and disruptive innovation in eco-tech, we recognize the need to review and establish working mechanisms that identify and examine issues that are critical to future sustainable development, to offer advice to decision-makers in different social sectors (public and private), to secure a shared future for mankind, and to achieve shared prosperity and common interests through international communications and collaborations.

Establishment of an indices system for evaluating the ecological-economic-social performances of wetland restoration projects (WRPs) is of significant importance for finding the WRPs achieving successful conservation outcomes and guiding financial investments on ecological restorations. In this study, two different indices systems were developed for WRPs I (with wetland park) and WRPs II (without wetland park) respectively. For WRPs I, the ecological performance were measured by 7 indexes: water quality, aquatic vegetation coverage, aquatic botanic biodiversity, plant community integrity, achievement of buffer function, habitat protection and improvement, and intensity of anthropogenic disturbance activities, while habitat protection and improvement and aquatic botanic biodiversity were excluded for measuring the ecological performances of WRPs II. Output value of wetland products, wetland tourism value, and increase of house price in the surrounding area of wetlands were used to measure the economic performance of WRPs I, while only one index of output value of wetland products was used for WRPs II. Integrity of management operating system, public awareness on wetland protection, public satisfaction, scientific education service, and job provision were applied to measure the social performance of WRPs I, while only one index of integrity of management operating system was used for WRPs II. By using weighted linear combination (WLC), the ecological-economic-social performances of WRPs were obtained. This new indices system was applied to 8 WRPs in Taihu Lake Basin, China. The results showed that among the 8 WRPs, 4 of them (Shangxianhe Wetland, Changguangxi Wetland, Lianghong Wetland, Daxigang Estuary Wetland) gained good grade in ecological-economic-social performance, whereas the Shibawan Lakeside Wetland, Daxigang Estuary Wetland, Dapugang Wetland, and Taihu Lake Shore Wetland were regarded as poor or very poor. In summary, only 50% of the WRPs gained good performance after implementation.

The use of ecological indicators in models has been a highly relevant topic in science and practice for several decades. Ecological indicators is a broad and diverse topic: for ecosystem and landscape organisation depiction, ecosystem health assessments, theoretical foundations of ecosystem dynamics, ecosystem service analyses, applications in environmental management, or human-environmental system analysis. The use of models is not less manifold, including not only computer-based simulation models but also conceptual models, data models, landscape models, hierarchy models, gradient models, theoretical and network models as well as economic and societal models. This Special Issue of Ecological Modelling is dedicated to our highly appreciated colleague Prof. Felix Mueller from Kiel, Germany, celebrating his 60th birthday in November 2014. We brought together a diverse and very international group of colleagues which accompanied Felix during the last decades and produced this collection of high quality scientific articles in a Special Issue. The topics of the 21 articles in the Special Issue are related to Felix' life and work, full of ecosystem indication, ecosystem theory, systems analysis, ecological modelling, ecosystem services, holistic indicator sets, and gradients on various spatial, temporal and interpersonal scales.

Lake Honghu,crossing over Honghu county and Jianli county in Hubei Province,China,is situated in the north of the middle reaches of Yangtze River.Because of unreasonable exploitation of wetland resources and discharge of pollutants,it confronted with series problems such as decrease of the lake area and wetland biodiversity,sharp reduction of rare species and its eutrophication of water body.Study for planktonic algae reflecting water ecological environment change will provide a scientific basis for protection of Lake Honghu.Algae are important composition of aquatic ecosystem;their community structure and function are adaptable to water environment,and vary with changing water environment.The characteristics of community structure can be used as an important index in the assessment of water quality.In order to understand the change of water environment in Lake Honghu,Hubei,China,we measured a set of variables related to water quality,including structure and density of algous community,water level(H),water temperature(tw),transparency(SD),permanganate index(CODMn),total nitrogen(TN),total phosphorus(TP) and chlorophyll a content(Chl-a).The above experiments were conducted monthly between 2009 and 2010 at the five sections in Lake Honghu.The nutrition state was evaluated with eutrophication index for Lake and Reservoir;the influence of some environmental factors on algous cell density was analyzed by correlation analysis and stepwise multiple regression;and some stepwise multiple regression equations were established.Analytical results showed that the water was in light eutrophication in Lake Honghu.Totally,7 phylum and 65 genera of planktonic algae were identified in the lake.The algous cell density ranged from 1.14 million cells per litre water to 32.4 million per litre water.Bacillariophyta was the most abundant phylum of planktonic algae,the following were Chlorophyta and Cyanophyta,in view of algous population distribution.Its algous community are 52.93% for Cyanophyta,25.96% for Bacillariophyta,16.83% for Cyanobacteria,1.98% for Cryptophyta,1.64% for Chrysophyta,0.42% for Euglenophyta,and 0.25% for Pyrrophyta.In light of structure and density of algous community change seasonally,the dominant species are Melosira and Cyclotena within Bacillariophyta in winter and spring,Anabaena of Chlorophyta in summer and autumn.There is a statistically significant positive relationship between algous cell density,water temperature and permanganate index,whereas there is no obvious relationship between algous cell density,water level,total phosphorus,total nitrogen and transparency.The Stepwise regression equation of growth for planktonic algae was that: y=3.7815+0.0794tw+0.5670CODMn-1.3467SD(R2=0.618,F=8.087,P0.02).This indicates that algous cell density could be used to reflect the pollution level caused by water temperature and organic pollutants,and the controlling of nitrogen and phosphorus has not been tone of the key factors.The characteristics of algous cell density are controlled by the different environmental conditions at the five sections,such as Bacillariophyta controlled by water temperature,permanganate index and transparency,Chlorophyta controlled by water level(H),water temperature and permanganate index,and Cyanophyta controlled by permanganate index.Based on the results,there are great significance for the effective measures on slowdown of water eutrophication and inhibit of the algous growth process in Lake Honghu,by controlling nitrogen,phosphorus and organic pollutants inputs of Sihu Main Cannal,reducing cages culture area,and restoring water connectivity of Yangtze River and Lake Honghu.

Understanding how plant species richness influences the diversity of herbivorous and predatory/parasitic arthropods is central to community ecology. We explore the effects of crop species richness on the diversity of pest insects and their natural enemies. Using data from a four-year experiment with five levels of crop species richness, we found that crop species richness significantly affected the pest species richness, but there were no significant effects on richness of the pests' natural enemies. In contrast, the species richness of pest insects significantly affected their natural enemies. These findings suggest a cascade effect where trophic interactions are strong between adjacent trophic levels, while the interactions between connected but nonadjacent trophic levels are weakened by the intermediate trophic level. High crop species richness resulted in a more stable arthropod community compared with communities in monoculture crops. Our results highlight the complicated cross-trophic interactions and the crucial role of crop diversity in the food webs of agro-ecosystems.

Ecosystem service is an emerging hot topic in the field of ecology. Temporal and spatial variations in human-induced land use change and climate variability have resulted in regional differences in dryland ecosystem services. Such information, however, is not enough. It is necessary to better understand such variations of ecosystem services to support policy-making and management in dryland areas. In the research, a case study was conducted in the ecologically vulnerable region of Central Asia. Land use and land cover change, net primary productivity (NPP), actual evapotranspiration (AET) and crop production were selected for evaluation. Substantial conversion of farmland to natural vegetation from 1990 to 2000 had led to a considerable decrease in farmland and crop production in the same period. With the reclamation of abandoned farmland in the recent 10 years, the crop production restored and reached a high and stable level. The NPP of farmland was significantly higher than that of natural vegetation. Despite of the decrease in precipitation, the NPP increased in 2000 with the rise of temperature. The AET was higher in the northern and eastern part than in the central area of Central Asia, and the mean AET of farmland was greatly lower than that of natural vegetation.

Comprehensive understanding on the response of net primary production (NPP) to grazing is still elusive. It is necessary to choose a suitable study area with significant differences in climate, landform, diverse grasslands and grazing intensity (GI), to better understand plant–herbivore interactions and what environmental conditions NPP may increase. This study used Biome-BGC model with inclusion of a grazing process and the effects of the excreta on vegetation to investigate the effects of grazing on the aboveground NPP (ANPP) in Tianshan Mountains-Junggar Basin with four grasslands along a climatic gradient from mountain to plain, i.e., alpine meadow (AM), mid-mountain forest-meadow (MMFM), low-mountain dry grassland (LMDG), and plain desert grassland (PDG). The model simulated ANPP agreed well with the measured values for both non-grazed and grazed experiments at four sites, suggesting that the model successfully captured the effects of grazing on ANPP. The model results based on different GI scenarios indicated that ANPP decreased with increasing GI at AM and MMFM. But at LMDG and PDG, ANPP increased when GI was smaller than optimal GI (GIopt). After GIopt, ANPP decreased with the increasing GI. This implied that appropriate GI stimulated ANPP at LMDG and PDG, with magnitude of 4.1–22% at LMDG and 6.6–15.7% at PDG. By investigating the annual evapotranspiration (ET) and soil volumetric water content under non-grazed and grazed conditions, it was found that grazing reduced ET and hence improved soil water at sites LMDG and PDG, which explained the different response of ANPP to GI in different grasslands. We concluded that the response of ANPP to GI highly depended on the climatic conditions in grassland ecosystems over Central Asia, and moderate grazing can promote ANPP under water stress.

Atmospheric water vapor transport (WVT) plays an important role in the Earth's climate system, especially in arid and semi-arid regions, but its physical mechanism has escaped wide attention. Here the distribution of WVT over Tarim River Basin and its relationships with local topography and precipitation are analyzed; the variation and trend of WVT and its correlation with westerly circulation index are also calculated; and the possible physical mechanism is discussed. All statistics and analysis are based on daily precipitation data of 25 weather stations in Tarim River Basin of China and NCEP/NCAR monthly mean reanalysis data (2.5° × 2.5°). It is shown that the western and the northwestern-based horizontal WVT is the main path for Tarim River Basin. But, the greatest contribution of the average annual water vapor net input (WVNI) is 3483.57 × 1011 kg a−1 through eastern boundary. According to Bernoulli's equation, the reason is that the U-shaped terrain around Tarim River Basin causes the shift of WVT from west and northwest to north and northeast. Moreover, in lower troposphere, there is a significant positive correlation between the zonal and meridional WVNI due to the U-shaped terrain. Additionally, zonal WVNI in upper and middle troposphere grow up steadily as well as westerly circulation index; but WVNI in lower troposphere, meridional WVNI in middle troposphere and horizontal WVNI in whole troposphere all decrease significantly. This implies that there are other factors that reduce the WVNI, which counteracts the increase of WVNI caused by enhanced west winds. Last but not least, due to the pumping function of plant on local moisture recycling, precipitation in mountains increased rapidly, but decreased smoothly in plains between the late 1970s and the early 21st century. So we can conclude that climate in interior regions links closely to the local moisture recycling, which depends, to a large extend, on local forest-covered situation; and that the trend of the drying and desertification in Tarim River Basin is not likely to slow down because of the block of the U-shaped terrain, decreasing of WVNI in meridian and sparse vegetation. However, we still do not know how the climate of TRB will develop. There are some other factors such as NAO, runoff and the East Asia Monsoon that need to be further explored. It is also very necessary and urgent to study the mutual feedback relationship between water cycle and climate, and we should pay more attention to the influence of ecosystem.

Human dominated landscape is a kind of Social-Economic-Natural Complex Ecosystem dominated by human behavior, sustained by natural life support system, and vitalized by ecological process, which is called ecoscape. Its natural subsystem consists of Chinese traditional five elements: metal (minerals), wood (living organism), water, fire (energy) and soil (nutrients and land). Its economic subsystem includes the components of production, consumption, reduction, transportation and regulation. While its social subsystem includes technology, institution and culture steered by man. In dealing with this eco-complexity, the key issue is how to image the complicated interactions, how to simplify and integrate the diversified relationships, and how to develop a practical instrument for cultivating the sustainability in helping local people to help themselves. Based on ancient Chinese human ecological philosophy, the SENCE approach for eco-sustainability planning and management was explored, which requires holistic rethinking, institutional reform and technological renovation. A combinatory model consists of mechanism model, planning model, and regulation model has been developed through identification of its key factors, feedback and function, simulation of its partial problems, process and alternative policies, and inducing its technological, institutional and cultural innovation towards sustainability.

Ecosystem stays far from thermodynamic equilibrium. Through the interactions among biotic and abiotic components, and encompassing physical environments, ecosystem forms a dissipative struc- ture that allows it to dissipate energy continuously and thereby remains functional over time. Biotic regula- tion of energy and material fluxes in and out of the ecosystem allows it to maintain a homeostatic state which corresponds to a self-organized state emerged in a non-equilibrium thermodynamic system. While the associated self-organizational processes approach to homeostatic state, entropy (a measure of irre- versibility) degrades and dissipation of energy increases. We propose here that at a homeostatic state of ecosystem, biodiversity which includes both phenotypic and functional diversity, attains optimal values. As long as biodiversity remains within its optimal range, the corresponding homeostatic state is maintained. However, while embedded environmental conditions fluctuate along the gradient of accelerating changes, phenotypic diversity and functional diversity contribute inversely to the associated self-organizing proc- esses. Furthermore, an increase or decrease in biodiversity outside of its optimal range makes the eco- system vulnerable to transition into a different state.