Search Results (13)

Due to the increasing impact of human activities on the environment, habitat loss, fragmentation, and degradation pose significant threats to bird diversity worldwide. Baiyangdian, the largest freshwater lake wetland in North China, is an important habitat for birds. The degradation of water quality caused by decaying reed rhizomes has prompted governmental initiatives for ecological restoration in Baiyangdian. However, it has also led to the significant destruction of reed habitats within the wetlands consequently. Bird species that rely on these reed habitats, especially the reed parrotbill, face a significant threat, necessitating the establishment of species reserves to mitigate the loss of bird diversity. Our research aims to identify the potential suitable habitats for the reed parrotbill in Baiyangdian and establish priority conservation areas. Using the environmental factors determined with Google Earth Engine (GEE), ultimately we designated the following areas as priority conservation zones: the Fuhe Wetland (FHW), the reed area south of Beihezhuang (BHV), both sides of the Baiyangdian Bridge (BYDB), the western shoreline of Shaochedian (SCD), Yannandi Park (YNDP), east of Guangdianzhangzhuang Village (GDZZV), east of Dongtianzhuang (DTV), north of Xilizhuang (XLV), south of Caiputai Village (CPTV), north of Gaolou Village (GLV), and the Xiaoyihe Wetland (XYW). Our findings provide a scientific reference for ecological restoration projects in the Baiyangdian region and offer supporting data for the conservation management of the reed parrotbill. Full article

With the drastic reduction in wetland areas, it is essential to conduct an annual monitoring of the biomass or carbon content of wetland ecosystems to support international initiatives and agreements focused on sustainable development, climate change, and carbon equity. Forests in wetland ecosystems play a crucial role in carbon sequestration; however, the monitoring of small, fragmented forest components in wetlands remains insufficient, leading to an underestimation of their ecological and carbon sequestration functions. This study utilizes a model-assisted (MA) estimator, a monitoring procedure that is asymptotically design-unbiased and incorporates remote sensing, to assess the status and trends in the above-ground biomass (AGB) of forest components in wetlands, while also proposing a method of optimizing the sample size to enable continuous monitoring. Based on the population of the forest component of Baiyangdian wetland, major findings indicate that: (1) neglecting the forest component of Baiyangdian wetland will lead to an underestimation of the total aboveground biomass by 224.34 t/ha and 243.64 t/ha in the years 2022 and 2023, respectively; (2) in either year-specific monitoring or interannual change monitoring, the MA estimator is more cost-effective than the expansion estimator, a comparable procedure that relies solely on field observations; (3) the method used to optimize sample size can effectively tackle the cost-related concerns of subsequent continuous monitoring. Overall, the neglect of forest components is inevitably bound to give rise to an underestimation of wetlands, and use of an MA estimator and optimizing the sample size could effectively address the cost issue in continuous monitoring. This holds significant importance when developing management strategies to prevent the further degradation of wetland ecological functions and carbon sink capabilities. Full article

Alert and flight initiation distances are important elements of bird behavioral responses and indicators of their adaptation to external disturbances; therefore, they provide an important basis for bird conservation. With continual rapid advancements in drone technology, the use of drones in bird field surveys is becoming increasingly important. However, the disturbance impact of drones on birds remains controversial and needs further assessment. This study measured the distances at which coots (Fulica atra) tolerated drones in the Baiyangdian wetland, Northern China, over 42 days from August to November 2023 and at the end of July 2024. The results show the maximum alert distance (AD) and maximum flight initiation distance (FID) of the coot to be 44 m and 35 m, respectively. The coots showed no signs of disturbance when the drones flew at an altitude of 50 m. The AD of the coot showed a significant relationship with whether it saw the drones in advance, environmental conditions, and the drone’s behavior before it approached, whereas the FID was only significantly affected by whether the coot saw the drones in advance. The sight of drones in advance considerably increased the AD and FID. Full article

The combined impacts of rapid urbanization and climate change pose significant threats to global biodiversity. To counter these threats, the establishment of appropriate habitats is becoming pivotal for species preservation. Due to positive ecological interventions, Baer’s Pochard (Aythya baeri), a critically endangered avian species per the International Union for Conservation of Nature (IUCN) classification, has made a remarkable resurgence in the wetlands of Baiyangdian (BYD). BYD, located in Xiong’an New Area, central North China, is the largest wetland and an ideal habitat for rare bird species. Our study focuses on identifying ideal habitats within BYD to further its conservation. To this end, unmanned aerial vehicles (UAV) integrated with GPS functionalities were utilized to collect occurrence data for the species. Furthermore, the Google Earth Engine (GEE) provided access to high-resolution, real-time satellite imagery. Our model exhibited substantial reliability, reflected by area under the curve (AUC) values of 0.917 and 0.934 for breeding and migration periods, respectively. During the breeding phase, the prime habitat for Baer’s Pochard spans 162 km², predominantly encompassing regions like Xiaobaiyangdian (XBYD), Zhaozadian (ZZD), Damaidian (DMD), and Shaochedian (SCD). Factors such as Distance to towns and Landcover predominantly influence breeding habitat selection. In the migration phase, ideal regions covered an expanse of 124 km², highlighting areas like northern and eastern SCD, the northwestern side of Datian Village (DTV) and Beitian Village (BTV) Fuhe Wetland (FHW), and Xiaoyihe Wetland (XYHW). The predominant determinants for migration habitat are Distance to towns and Wetness. These insights offer a fundamental foundation for the conservation and management strategies of Baer’s Pochard in BYD, presenting a roadmap for future conservation endeavors. Full article

Lakes are hot spots of carbon cycles in inland aquatic systems. As a vital factor, meteorology, including air temperature, precipitation, wind speed and evapotranspiration, is profoundly affecting or even regulating the wetland-air CO₂ exchanges. Compared with some other similar lakes in China, the largest shallow grass-type Baiyangdian Lake (BYDL) acts as a vital CO₂ sink on the North China Plain. The purpose of this study is to reveal the effects of meteorology on the process of CO₂ flux variation. Based on the method of the eddy covariance, the daily average wetland-air CO₂ flux at the BYDL over the monitoring period from April 2019 to November 2020, reached −0.63 μmol m⁻² s⁻¹, and the annual average reached −0.71 μmol m⁻² s⁻¹ from 12 April 2019 to 12 April 2020. The CO₂ sink fluxes varied with the seasons and reached the maximum in summer. Temperature and evapotranspiration are two major driving factors, whose higher values can positively improve the wetland CO₂ sinks. Precipitation generally coincides with the CO₂ sinks, but the relatively larger summertime precipitation (0.39 m in 2020, compared with that of 0.17 m in 2019) inhibits the CO₂ uptakes on longer timescales. A moderate wind speed in the range of 1.6~3.3 m s⁻¹, promoted the CO₂ sinks for the shallow grass-type lake. Compared with previous studies at the same or similar wetlands, consistent CO₂ sink fluxes are found. Further in this study, the variation trends of CO₂ sinks with the changing meteorological factors are revealed for the first time in this type of wetland. Once meteorology is determined under both the anthropogenic and climatic impacts, the evaluation and prediction of the lacustrine carbon cycling could be more precise. Generally, this study will serve as an important data point into the global understanding of lake carbon fluxes. Full article

Macrophytes are the main primary producers in lake ecosystems and are the main transmitters of material and energy flows in lake ecosystems, directly influencing the structure and function of lake ecosystems. The balanced harvesting of aquatic plants is a cost-effective scientific management approach to maintain ecosystem health. The article defines “balanced harvesting” as an aquatic plant harvesting technique to optimize the structure of aquatic plant communities, maintain the normal function of the ecosystem material cycle and energy flow, and enhance the stability and resilience of the system. The ecological significance of balanced harvesting in regulating the evaporation coefficient of the subsurface, reducing the accumulation and release of endogenous nutrient loads in lakes, delaying the evolutionary process of marshification, inhibiting biological filling, increasing biodiversity and system stability, and improving the environment of water bodies under the natural laws of adapted aquatic plants is reviewed. The way, time, and method of the balanced harvesting of aquatic plants in Baiyangdian, a grass-type lake in the north, were analyzed in order to provide an important reference for wetland ecological restoration and protection, maintaining the health of the aquatic ecosystem, and making the lake environment sustainable. Full article

Chlorophyll-a is an important parameter that characterizes the eutrophication of water bodies. The advantage of ZY1-02D hyperspectral satellite subdivision in the visible light and near-infrared bands is that it highlights the unique characteristics of water bodies in the spectral dimension, and it helps to assess the Class II water bodies of inland lakes and reservoirs, making it an important tool for refined remote sensing detection of the environment. In this study, the Baiyangdian Nature Reserve in northern China, which contains a typical inland lake and wetland, was chosen as the study area. Using ZY1-02D hyperspectral synchronization transit images and in situ measured chlorophyll-a concentration as the data source, remote sensing of the chlorophyll-a concentration of inland lakes was conducted. By analyzing the correlation between the spectral reflectance of the ZY1-02D hyperspectral image and the chlorophyll-a concentration and using algorithms such as the single band, band ratio, and three bands to compare and filter characteristic wavelengths, a quantitative hyperspectral model of the chlorophyll-a concentration was established to determine the chlorophyll-a concentration of Baiyangdian Lake. The dynamic monitoring of the water body and the assessment of the nutritional status of the water body were determined. The results revealed that the estimation of the chlorophyll-a concentration of Baiyangdian Lake based on the hyperspectral Fluorescence Line Height (FLH) model was ideal, with an R² value of 0.78. The FLH model not only comprehensively considers the effects of suspended solids, yellow substances, and backscattering of the water body on the estimation of the chlorophyll-a concentration, but also considers the influence of the elastic scattering efficiency of the chlorophyll. Based on the ZY1-02D hyperspectral data, a spatial distribution map of the chlorophyll-a concentration of Baiyangdian Lake was created to provide new ideas and technical support for monitoring inland water environments. Full article

The spatiotemporal features of land use changes and the evolution process of landscape pattern from 1980 to 2017 were investigated using historical satellite images from a Landsat Thematic Mapper (TM) for 1980, 1990, 2000, 2005, 2010 and 2017 in the wetlands of Lake Baiyangdian in the North China Plain (NCP). Landscape pattern indices were used to quantify landscape changes in wetlands, and a redundancy analysis (RDA) was conducted to analyze the driving forces and quantitatively explain the effects of human activities and natural changes on wetland fragmentation. The results showed that the total wetland area was 234.4 km² in 1980 but it decreased by 8.1% at an average decrease rate of 0.5 km² per year. The dominant transition between land use types was from natural wetlands to artificial wetlands, and wetland conversion to dry land and residential land. The RDA results suggested that agricultural activities and total population were the main driving factors affecting wetland landscape. Additionally, climate change provided a potentially favorable environment for agricultural development, due to the increased temperatures and decreased wind speeds. Additionally, governmental policy changes and dam construction also played the roles in land use changes. Full article

River system network (RSN) connectivity is important to maintain the environmental and ecological functions of wetlands. Quantitative evaluation of connectivity can provide crucial support for efforts to improve wetland connectivity and to restore and protect wetland ecosystems. Most existing evaluation methods uniformly generalise RSN to form an undifferentiated RSN of edges and nodes that is taken as a whole to evaluate the connectivity. However, actual RSNs comprise rivers, canals, ditches, lakes, and ponds, which differ substantially in their structures, morphologies, and attributes. The mix of RSN elements therefore defines grades that give RSNs distinctive characteristics. Moreover, RSNs with different grades perform different ranges of environmental and ecological functions. The existing evaluation methods, which have some limitations, do not account for these characteristics. To account for these differences, we examined the grade characteristics and their impact on environmental and ecological functions. We established a grading system of RSN elements and a grading method of RSN, and constructed the structural connectivity evaluation indicator system for RSNs at different grades. On this basis, we propose a method for grading evaluation of RSN connectivity. We used China’s Baiyangdian Wetland to demonstrate the use of the system and validate the results. The proposed method provided an objective and accurate evaluation of RSN connectivity and clarified the differences in connectivity among RSNs with different grades, thereby providing improved guidance for the development and maintenance of the environmental and ecological functions of RSNs. Full article

Wetland landscape patterns are the result of various ecological and hydrological processes. Based on the land use landscape types from 1980 to 2017, a transfer matrix, landscape pattern analysis index, and principal component analysis were used to analyze the landscape pattern evolution in the Xiong’an New Area of China, which has a large area with a lake and river wetlands. The results showed that the wetland area has changed greatly since 2000 and the beach land has decreased greatly, while the area of the lake and river wetlands has increased slightly. Beach land was the dominant landscape type of the wetland. The dominant degree of the wetland landscape showed a slightly decreasing trend, and the patches tended to be scattered. The shape complexity of the ponds was the lowest, while that of rivers was the highest. The fragmentation degree of the wetland patches increased, the proportion of landscape types tended to be equalized, and the landscape heterogeneity increased. The leading factors of the wetland landscape change can be summarized as socioeconomic, meteorological, and hydrological processes, with a cumulative contribution rate of 85.3%, among which socioeconomic development was the most important factor. The results have important guiding significance for the ecological restoration and management of wetlands in the Xiong’an New Area and other wetland ecosystems with rivers and lakes. Full article

Hydrological connectivity is an important characteristic of wetlands that maintains the stability and functions of an ecosystem. This study investigates the temporal variations of hydrological connectivity and their driving mechanism in Baiyangdian Lake, a large shallow wetland in North China, using a time series of open water surface area data derived from 36 Landsat 8 multispectral images from 2013–2019 and in situ measured water level data. Water area classification was implemented using the Google Earth Engine. Six commonly used indexes for extracting water surface data from satellite images were compared and the best performing index was selected for the water classification. A composite hydrological connectivity index computed from open water area data derived from Landsat 8 images was developed based on several landscape pattern indices and applied to Baiyangdian Lake. The results show that, reflectance in the near-infrared band is the most accurate index for water classification with >98% overall accuracy because of its sensitivity to different land cover types. The slopes of the best-fit linear relationships between the computed hydrological connectivity and observed water level show high variability between years. In most years, hydrological connectivity generally increases when water levels increase, with an average R² of 0.88. The spatial distribution of emergent plants also varies year to year owing to interannual variations of the climate and hydrological regime. This presents a possible explanation for the variations in the annual relationship between hydrological connectivity and water level. For a given water level, the hydrological connectivity is generally higher in spring than summer and autumn. This can be explained by the fact that the drag force exerted by emergent plants, which reduces water flow, is smaller than that for summer and autumn owing to seasonal variations in the phenological characteristics of emergent plants. Our study reveals that both interannual and seasonal variations in the hydrological connectivity of Baiyangdian Lake are related to the growth of emergent plants, which occupy a large portion of the lake area. Proper vegetation management may therefore improve hydrological connectivity in this wetland. Full article

Wetlands store a large amount of carbon (C) and many are vulnerable to potential global warming. It is critical to quantify the temperature sensitivity of soil nitrogen (N) and C mineralization in response to external labile C or N addition in different types of wetland. Through incubation experiments, the effects of temperature and the addition of N or C on soil C and N mineralization were tested using soils from the Sanjiang Plain wetland (SW), Zoigê alpine wetland (ZW), Yellow River estuary wetland (YW), and Baiyangdian Lake (BL). Our findings showed that temperature, available C and wetland type were dominant factors in the regulation of soil C loss, with soil C in SW and ZW being less stable and poorly resistant to increases in temperature. The response of net N mineralization to N addition showed regional differences. A lack of long-term effects of the deposition of N on soil mineralization suggested that there may be a particular N addition threshold level for changed C and N mineralization. It is predicted that an increase in labile C supply due to elevated carbon dioxide (CO₂) and its interactions with wetland types will increase CO₂ efflux more than N deposition in wetland soils. Full article

Wetlands have been degrading and reducing under the influences of human activity and climate change. Landsat long-term observations can help us better track the changing evidences of wetland habitats that would be valuable for guiding the restoration and conservation of wetland. In this study, we demonstrated the results of tracking the changing evidence of wetland habitats using Landsat observations from 1984 to 2017 through the case study of Baiyangdian wetland in China. We extracted the open water and classified the wetland habitats using collected 190 scenes from Landsat observations. As a result, we found that the yearly variations of wetland present phasic changes in three phases: 1988–1998, 1999–2011 and 2013–2017. The landscape of wetland habitats presented during 1989–1999 mostly show us the natural spatial pattern with less human disturbance traces compared to that during 2013–2017. The water environment, moreover, changed for the better after the 2010s, which indicated the encouraging effects of the environmental restoration project implemented from the year 2010. The current landscapes of wetland habitats, however, present lots of linear belts that are blocking the water cycles and ecological channels of aquatic plants and animals in the wetland. The areas in the northwestern wing and around the northeastern edge of the wetland are changing to be drier due to cropping activities and are at risk of wetland loss. These historical changing evidences could be a guideline for planning and designing restoration for the wetland. Full article