A Holistic Wetland Ecological Water Replenishment Scheme with Consideration of Seasonal Effect

Spatiotemporal variations and tradeoff-synergy relations of ecosystem services under ecological water replenishment in Baiyangdian Lake, North China

Understanding dynamic variations of ecosystem services (ESs) and their tradeoff-synergy relations under ecological water replenishment (EWR) is conducive to the formulation of effective eco-environmental management strategies. In this study, spatiotemporal variations of three leading ESs, namely habitat quality, carbon storage and water yield services influenced by EWR in Baiyangdian Lake, North China from 1991 to 2019, were investigated using the "Integrated Valuation of Ecosystem Services and Tradeoffs" (InVEST) model, and their tradeoff-synergy relations were quantitatively assessed with correlation analysis methods. Our results showed that habitat quality had continuously declined, whereas it got a steady improvement after the year of 2015. Total carbon storage was relatively stable, and the volume of total water yield and precipitation showed the same variation trend. Overall, EWR promoted the maintenance and improvement of ESs. Tradeoff-synergy relations among ESs varied with time and space. Temporally, there was an obvious synergistic relation between habitat quality and carbon storage services. Spatially, these two ESs were synergistic in the southern, central and eastern parts of the lake, while they had a tradeoff relation in the north; and there were no tradeoff-synergy relations between the water yield service and these two services. This study confirmed the importance of zoning management and comprehensive multi-factor management based on spatial and temporal differences of ESs, and can offer a scientific basis for adaptive eco-environmental management strategies for wetland restoration.

Ecological Service Value Tradeoffs: An Ecological Water Replenishment Model for the Jilin Momoge National Nature Reserve, China

Wetlands as an important ecosystem type have been damaged in recent years and restoration of wetland ecosystem functions through ecological water replenishment is one of the important ways. The present study involved the construction of a novel ecological water replenishment model for Jilin Momoge National Nature Reserve (JMNNR) using the interval two-stage stochastic programming (ITSP) method. Breaking down traditional economic models that often sacrifice environmental benefits, the model aims to replenish the ecological water in JMNNR, allocate the ecological water resources scientifically, restore the wetland function of the reserve, improve the functional area of the reserve, enhance the net carbon sequestration capacity of the reserve, and complete the reconstruction of the ecosystem, while considering the ecological service value (ESV) of the reserve to achieve a joint increase in the ecological and economic benefits. The ITSP model constructed in the present study overcame the limitation that the original project recommendation was a single recommended value, and the results are presented in the form of intervals to improve flexibility in decision making to allow the individuals responsible for under-taking decisions to bring focused adjustments according to the actual decision-making conditions and increase the selectivity of the decision-making scheme. The present report discusses the construction of an ITSP model for the ecological water replenishment of JMNNR in an attempt to effectively improve both economic benefits and ecosystem restoration of the reserve, achieve the reconstruction of the JMNNR ecosystem, and provide a selective decision space for the key decision-makers to formulate and optimize the project operation and the management plan. The use of the ITSP model as a pre-procedural basis for the implementation of the project and the simulation of the effects of the implementation of the project can effectively avoid the decision limitations that exist when carrying out the project directly. The ITSP model constructed in this paper can also be used as a theoretical guide for water replenishment projects in different areas of the world, and the model parameters can be reasonably adjusted to achieve better results when used according to the actual local conditions.

A Novel Workflow for Seasonal Wetland Identification Using Bi-Weekly Multiple Remote Sensing Data

Accurate wetland mapping is essential for their protection and management; however, it is difficult to accurately identify seasonal wetlands because of irregular rainfall and the potential lack of water inundation. In this study, we propose a novel method to generate reliable seasonal wetland maps with a spatial resolution of 20 m using a seasonal-rule-based method in the Zhalong and Momoge National Nature Reserves. This study used Sentinel-1 and Sentinel-2 data, along with a bi-weekly composition method to generate a 15-day image time series. The random forest algorithm was used to classify the images into vegetation, waterbodies, bare land, and wet bare land during each time period. Several rules were incorporated based on the intra-annual changes in the seasonal wetlands and annual wetland maps of the study regions were generated. Validation processes showed that the overall accuracy and kappa coefficient were above 89.8% and 0.87, respectively. The seasonal-rule-based method was able to identify seasonal marshes, flooded wetlands, and artificial wetlands (e.g., paddy fields). Zonal analysis indicated that seasonal wetland types, including flooded wetlands and seasonal marshes, accounted for over 50% of the total wetland area in both Zhalong and Momoge National Nature Reserves; and permanent wetlands, including permanent water and permanent marsh, only accounted for 11% and 12% in the two reserves, respectively. This study proposes a new method to generate reliable annual wetland maps that include seasonal wetlands, providing an accurate dataset for interannual change analyses and wetland protection decision-making.

Review on strategies of close-to-natural wetland restoration and a brief case plan for a typical wetland in northern China

Wetlands play an important role in sustaining ecosystems on the earth, which regulate water resources, adjust local climate and produce food for human beings, etc. However, wetlands are facing huge challenges due to human activities and other natural evolution, such as area shrinkage, function weakening and biodiversity decrease, and so on, therefore, some wetlands need to be urgently restored. In this study, the main technology components of close-to-natural restoration of wetlands were summarized. The ecological water requirement and water resource allocation can be optimized for the water balance between social, economy and ecology, which is a key prerequisite for maintaining wetland ecosystem. The pollution of wetland sediments and soils can be assessed by various indicators to provide the scientific basis for natural restoration of wetland base, and suitable strategies should be taken according to the actual conditions of wetland bases. The hydrological connectivity in wetlands and with related water system can be numerically simulated to make the optimal plan for improvement of hydrological connectivity. The ecological restoration of wetlands with the synergetic function of plants, animals and microorganisms was summarized, to improve the quality of wetland water environment and maintain the ecosystem stability. Based on the wetland close-to-natural restoration strategies, a brief ecological restoration plan for a typical wetland, Zaozhadian Wetland, near Xiong'an New Area in the north China was proposed from water resource guarantee, base pollution management, hydrological connectivity improvement and biological restoration. The close-to-natural restoration shows more effective, sustainable and long-lasting and thus a practical prospect.