A limited overlap of interactions between the bacterial community of water and sediment in wetland ecosystem of the Yellow River floodplain

Introduction

Aquatic ecosystems in floodplains provide homes for a variety of active bacterial populations. However, the coexistence pattern of bacterial communities of water and sediment in these ecosystems is unclear.

Methods

In the present study, Illumina Mi-Seq sequencing were to assess bacteria's co-occurrence patterns in the water and sediment of different time dynamics and plant communities of the Yellow River floodplain ecosystem.

Results and discussion

The results showed that compared to water, the α-diversity of the bacterial community was way greater in sediment. The bacterial community structure significantly differed between water and sediment, and there was a limited overlap of interactions between the bacterial community of water and sediment. In addition, bacteria in water and sediment coexisting show different temporal shifts and community assembly patterns. The water was selected for specific groups of microorganisms that assemble over time in a non-reproducible and non-random way, whereas the sediment environment was relatively stable, and the bacterial communities were gathered randomly. The depth and plant cover significantly influenced the structure of a bacterial community in the sediment. The bacterial community in sediment formed a more robust network than those in water to cope with external changes. These findings improved our comprehension of the ecological trends of water and sediment bacterium colonies coexisting enhanced the biological barrier function, and the capacity of floodplain ecosystems to provide services and offered support for doing so.

Transformation Path of Ecological Product Value and Efficiency Evaluation: The Case of the Qilihai Wetland in Tianjin

In order to protect wetland resources, China has developed wetland conservation policies and has made significant conservation investments, but there is still a lack of pathways for the conversion to economic value, making it difficult to meet the demand for continuous investment. We have explored a sustainable ecological conservation mechanism using the Seven Mile Sea as a case study, so that ecological conservation costs can be transformed into economic development behaviors and ecological benefits and socio-economic development can be integrated. This paper assesses the ecological product value of the Qilihai Wetland based on the ecosystem service function value assessment method, which designs the realization path of ecological product value and predicts the value transformation efficiency. The results show the following: (1) The total value of ecological products in the study area is CNY 569.06 million (USD 78.36 million), and the main sources of value are plant products in the supply service and water purification functions in the regulation service, accounting for 54.05% and 26.10% of the total, respectively. (2) The predicted value realization of ecological products, ideally, is CNY 689.65 million (USD 94.96 million), with a value realization rate of 111.60%. Considering the management policy restrictions in different areas of the Qilihai Wetland, the actual value realization volume is CNY 391.94 million (USD 53.97 million), with a value realization rate of 63.42%. (3) Owing to the restriction of the development policy of supply services and cultural services, the value realization path mainly contains two types: one is to drive the development of supply services and cultural services in the surrounding areas, along with product premiums, to realize value transformation. This path is mainly aimed at the supply of local characteristic products and the development of tourism. The second is to realize the value of regulating services through ecological compensation and ecological equity trading. This path is mainly for the adjustment and support services in the core area and buffer area. According to the pre-accounting results, the contribution rates of the two paths are 62.25% and 37.75%, respectively. The second path should be further effectively developed to improve the contribution rate. This study helps assess the ecological value and important ecological elements of the Qilihai Wetland to ensure effective protection and development of important ecological resources and to achieve the sustainable development of wetland resources. It provides a reference for exploring feasible paths to realize the value of ecological goods.

Spatial and Temporal Variability and Driving Factors of Carbon Dioxide and Nitrous Oxide Fluxes in Alpine Wetland Ecosystems

Plants regulate greenhouse gas (GHG) fluxes in wetland ecosystems, but the mechanisms of plant removal and plant species that contribute to GHG emissions remain unclear. In this study, the fluxes of carbon dioxide (CO2) and nitrous oxide (N2O) were measured using the static chamber method from an island forest dominated by two different species, namely Betula platyphylla (BP) and Larix gmelinii (LG), in a marsh wetland in the Great Xing’an Mountains. Four sub-plots were established in this study: (1) bare soil after removing vegetation under BP (SBP); (2) bare soil after removing vegetation under LG (SLG); (3) soil with vegetation under BP (VSBP); and (4) soil with vegetation under LG (VSLG). Additionally, the contributions of the dark respiration from plant aerial parts under BP (VBP) and LG (VLG) to GHG fluxes were calculated. We found that the substantial spatial variability of CO2 fluxes ranged from −25.32 ± 15.45 to 187.20 ± 74.76 mg m−2 h−1 during the study period. The CO2 fluxes decreased in the order of SBP > VSLG > VSBP > SLG > VLG > VBP, indicating that vegetation species had a great impact on CO2 emissions. Particularly, the absence of vegetation promoted CO2 emission in both BP and LG. Additionally, CO2 fluxes showed dramatically seasonal variations, with high CO2 fluxes in late spring (May) and summer (June, July, and August), but low fluxes in late summer (August) and early autumn (September). Soil temperatures at 0−20 cm depth were better predictors of CO2 fluxes than deeper soil temperatures. N2O fluxes were varied in different treatments with the highest N2O fluxes in SLG and the lowest N2O fluxes in VBP. Meanwhile, no significant correlation was found between N2O fluxes and air or soil temperatures. Temporally, negative N2O fluxes were observed from June to October, indicating that soil N2O fluxes were reduced and emitted as N2, which was the terminal step of the microbial denitrification process. Most of the study sites were CO2 sources during the warm season and CO2 sinks in the cold season. Thus, soil temperature plays an important role in CO2 fluxes. We also found that the CO2 flux was positively related to pH in a 10 cm soil layer and positively related to moisture content (MC) in a 50 cm soil layer in VSBP and VSLG. However, the CO2 flux was negatively related to pH in a 30 cm soil layer in SBP and SLG. Our findings highlight the effects of vegetation removal on GHG fluxes, and aid in the scientific management of wetland plants.

Non-native plant invasion can accelerate global climate change by increasing wetland methane and terrestrial nitrous oxide emissions

Approximately 17% of the land worldwide is considered highly vulnerable to non-native plant invasion, which can dramatically alter nutrient cycles and influence greenhouse gas (GHG) emissions in terrestrial and wetland ecosystems. However, a systematic investigation of the impact of non-native plant invasion on GHG dynamics at a global scale has not yet been conducted, making it impossible to predict the exact biological feedback of non-native plant invasion to global climate change. Here, we compiled 273 paired observational cases from 94 peer-reviewed articles to evaluate the effects of plant invasion on GHG emissions and to identify the associated key drivers. Non-native plant invasion significantly increased methane (CH₄ ) emissions from 129 kg CH₄ ha^-1  year^-1 in natural wetlands to 217 kg CH₄ ha^-1  year^-1 in invaded wetlands. Plant invasion showed a significant tendency to increase CH₄ uptakes from 2.95 to 3.64 kg CH₄ ha^-1  year^-1 in terrestrial ecosystems. Invasive plant species also significantly increased nitrous oxide (N₂ O) emissions in grasslands from an average of 0.76 kg N₂ O ha^-1  year^-1 in native sites to 1.35 kg N₂ O ha^-1  year^-1 but did not affect N₂ O emissions in forests or wetlands. Soil organic carbon, mean annual air temperature (MAT), and nitrogenous deposition (N_DEP) were the key factors responsible for the changes in wetland CH₄ emissions due to plant invasion. The responses of terrestrial CH₄ uptake rates to plant invasion were mainly driven by MAT, soil NH₄ ⁺ , and soil moisture. Soil NO₃ ^- , mean annual precipitation, and N_DEP affected terrestrial N₂ O emissions in response to plant invasion. Our meta-analysis not only sheds light on the stimulatory effects of plant invasion on GHG emissions from wetland and terrestrial ecosystems but also improves our current understanding of the mechanisms underlying the responses of GHG emissions to plant invasion.

Wetland ecosystem service function and its value accounting:A case study of Fuzhou City, China

Wetland plays an important role in ecological protection and social development. Scientific and rational evaluation of the values of wetland ecosystem service is the basis of protection and sustainable utilization of wetland resources. How to scientifically and effectively assess the wetland ecosystem gross ecosystem product (GEP) and make it into the national GDP accounting system are the focus of the scientific community and government departments. In this study, the accounting framework of wetland ecosystem GEP was constructed. Based on multi-source data and from the aspects of function and value, the accounting of wetland GEP in Fuzhou City was carried out. The results showed that the GEP of wetland ecosystem in Fuzhou City was 239.23 billion yuan in 2015. Such value mainly came from the ecological regulation service value (157.869 billion yuan), which accounted for 66.0% of the total and was about 2.2 and 15.6 times of the product supply service value and cultural service value. Among the ecological regulation services of wetlands, hydrodynamic regulation service and climate regulation service were the highest. Together, they accounted for 82.9% of the ecological regulation service value. The ecological regulation value per unit area of wetland in Fuzhou City was 1347.8 thousand yuan·hm^-2, which was higher than the mean level of the whole country. In the districts and counties of Fuzhou City, the value of wetland ecosystem in Minqing County was the largest, about 88.83 billion yuan, accounting for 40.1% of the total value of product supply and ecological regulation. In terms of types, coastal wetlands in Fuzhou City had the largest function of ecological regulation services, which was about 2.5 times of that of river wetlands and constructed wetlands. The accounting of GEP of wetland ecosystem in Fuzhou City is an important practice for the conviction of "lucid waters and lush mountains are invaluable assets", which would provide technical support for guiding local government to scientifically manage wetland ecosystem.

Organically Linking Green Development and Ecological Environment Protection in Poyang Lake, China Using a Social-Ecological System (SES) Framework

Wetlands are unique ecosystems formed by the interaction between land and water on Earth. Poyang Lake, which is a part of China’s largest freshwater lake wetland, is well known for its ecological and economic importance. This study uses a social-ecological system (SES) framework that integrates watershed and human activities; we used action scenarios to analyse the influencing factors, solutions, and feedback mechanisms involved in the SES framework. We chose Nanchang, Jiujiang, and Shangrao in the Poyang Lake wetlands of the Jiangxi province as the study areas to provide a problem-oriented analytical strategy for the organic interface between ecological conservation and green development. The key issues indicate that the Poyang Lake region faces multiple problems, such as ecosystem structural changes and environmental pollution, caused by anthropological activities, inefficient implementation of conservation policies, and insufficient funding for pollution prevention and control. Our findings provide a systematic solution for major conservation and development issues in the Poyang Lake region and are adapted to the characteristics of the lake. We also provide a theoretical reference and direction for the implementation of green development and modernisation of ecological governance in the Great Lakes basin in China.

Dynamic Evaluation of Ecological Service Function Value of Qilihai Wetland in Tianjin

This study, using the method of economic quantitative analysis, studied the land use changes of Qilihai Wetland from 2008 to 2017, and the effects of these changes on the ES (ecosystem service) values of the wetland. This article benchmarked the 2030 Agenda for Sustainable Development, based on the systematic analysis and analysis of current ecological service function value evaluation methods. The research results show that the total values of the wetland ecosystem services in 2008, 2011, 2014, and 2017 were 317 million yuan, 299 million yuan, 283 million yuan, and 321 million yuan, respectively. In 2008 and 2011, the ES of the Wetland was mainly based on supply and support services, and in 2014 and 2017, it was mainly based on supply and regulation services. Changes in human utilization, natural conditions, and social economy will all lead to changes in the ES value of the whole Wetland. This research can enable decision makers to intuitively understand its ecological changes and plan the use of land and formulate ecological protection measures in a reasonable and effective manner. Finally, the article puts forward relevant suggestions for sustainable development based on the resource and environmental foundation and characteristics of Qilihai Wetland.

[Research progress on food sources and food web structure of wetlands based on stable isotopes]

The trophic dynamics of wetland organisms is the basis of assessing wetland structure and function. Stable isotopes of carbon and nitrogen have been widely applied to identify trophic relationships in food source, food composition and food web transport in wetland ecosystem studies. This paper provided an overall review about the current methodology of isotope mixing model and trophic level in wetland ecosystems, and discussed the standards of trophic fractionation and baseline. Moreover, we characterized the typical food sources and isotopic compositions of wetland ecosystems, summarized the food sources in different trophic levels of herbivores, omnivores and carnivores based on stable isotopic analyses. We also discussed the limitations of stable isotopes in tra-cing food sources and in constructing food webs. Based on the current results, development trends and upcoming requirements, future studies should focus on sample treatment, conservation and trophic enrichment measurement in the wetland food web, as well as on combing a variety of methodologies including traditional stomach stuffing, molecular markers, and multiple isotopes.

[Construction and analysis of the EWE model of the wetland ecosystem in lake buffering zone of Zhushan Bay, China.]

Lake buffering zones play a special role in spatial arrangement of the lake watershed, and the wetland in buffering zones also is of great significance in basin ecological health and lake water environmental quality. Taking Zhushanhu wetland ecosystem in the area of lake buffering zone of Zhushan Bay, Lake Taihu as the research object, the biotic components were divided into 16 functional groups to construct the Ecopath with Ecosim (EWE) model, and the characteristics and state of the ecosystem and the interrelation between the functional groups were analyzed. The results showed that the range of effective trophic level in Zhushanhu wetland ecosystem was 1-3.72, tro-phic flows were mainly concentrated in the first 4 trophic levels, and most of the food chains started from submerged plants and detritus. The total energy conversion efficiency of the wetland ecosystem was 5.1%, being lower than the "1/10 law", indicating that the current energy conversion efficiency was low. The average transmission efficiency of material throughput in the ecosystem was 4.3%. The sum of all production in the ecosystem was 2496.66 t·km^-2·a^-1, and the total system throughput was 10145.2 t·km^-2·a^-1. The characteristic parameters of ecosystem showed that the current ecosystem was at the immature stage.