Habitat selection of wintering cranes (Gruidae) in typical lake wetland in the lower reaches of the Yangtze River, China

Habitat quality assessment of wintering migratory birds in Poyang Lake National Nature Reserve based on InVEST model

Poyang Lake National Nature Reserve (PLNNR) is an important resting place for wintering migratory birds on the East Asian-Australasian Flyway (EAAF). In recent years, due to human activities and climate change, the area of wetlands has shown a downward trend, and the number and habitat of wintering migratory birds have been threatened. It is urgent to evaluate the habitat quality of wintering migratory birds in PLNNR. Therefore, the InVEST model and landscape index were used to evaluate the habitat quality of wintering migratory birds, and the grey correlation theory was used to reveal the response of typical wintering migratory bird population to habitat quality. The results showed that the habitat quality of the PLNNR was still at a high level, but showed a downward trend, with the average index of habitat quality decreasing from 0.872 to 0.817. The area of the highest quality habitat decreased by 3394.92 hm², the area of the lowest, low, and medium quality habitats increased by 3112.11 hm², and the area of the high quality habitat remained stable. The lowest, low, and medium quality habitat expanded from the middle to the south of the PLNNR mainly because of the expansion of construction land and cultivated land. The area with deterioration in habitat quality was 10,477.53 hm², mainly concentrated in the center and south of the PLNNR. The area with restoration in habitat quality was 6148.26 hm², mainly concentrated in the Bang Lake and Dacha Lake. The area with no change in habitat quality remained stable. The fragmentation degree and shape complexity of highest and high quality habitats increased, dominance degree and connectivity decreased, and the landscape pattern of habitat quality showed a downward trend. Typical wintering migratory birds have a strong correlation with highest, high, and low habitat quality, and there is a downward trend with the deterioration of habitat quality. Finally, this paper puts forward constructive suggestions on the degradation of habitat quality caused by land-use change.

Initial recovery of fish faunas following the implementation of pen-culture and fishing bans in floodplain lakes along the Yangtze River

Given the decline of natural fish abundance and diversity, a ban on pen-culture and fishing has been imposed on floodplain lakes along the Yangtze River. In order to examine the recovery efficiency of fish faunas, we compared the changes in multidimensional (α and β) diversity in the Shengjin Lake between pen-culture stage (PS) and recovery stage (RS). Our results demonstrated significant variations in fish community composition, with distinct populational restoration in wild species of high trophic level and river-lake migratory species. The higher abundance of wild and migratory species in RS implied the enhanced dispersal and exchange process of fish individuals with the elimination of net pens. Despite significant variations of community composition, the α and β diversity indices exhibited non-significant change between PS and RS. However, our study still revealed the recovery of natural seasonal community dynamics, since there were significant variations of both α and β diversity between high-water (HW) and low-water (LW) seasons in RS. The significant higher α diversity (S, d, H') in HW indicated flooding induced fish supplements in floodplain lakes, due to the well-developed breeding sites, nurseries and refuges provided by floodplain lakes. Meanwhile, the significant lower β_SOR and β_SIM in HW implied the homogenized communities during flooding seasons, which can be ascribed to better hydrological connectivity of various habitats and more even distribution of fish faunas triggered by flood pulses. The reappearance of natural seasonal variations in multidimensional (α and β) diversity indicate the initial recovery of fish faunas. There is a pressing need for prolonged surveillance to explore the recovery mechanism of fish assemblage. Meanwhile, our results also highlight the importance of conserving the lacustrine connectivity and seasonal flooding for the recovery of fishery resources in the floodplain lakes.

Combining Tracking and Remote Sensing to Identify Critical Year-Round Site, Habitat Use and Migratory Connectivity of a Threatened Waterbird Species

We tracked 39 western flyway white-naped cranes (Antigone vipio) throughout multiple annual cycles from June 2017 to July 2020, using GSM-GPS loggers providing positions every 10-min to describe migration routes and key staging areas used between their Mongolian breeding and wintering areas in China’s Yangtze River Basin. The results demonstrated that white-naped cranes migrated an average of 2556 km (±187.9 SD) in autumn and 2673 km (±342.3) in spring. We identified 86 critical stopover sites that supported individuals for more than 14 days, within a 100–800 km wide migratory corridor. This study also confirmed that Luan River catchment is the most important staging region, where white-naped cranes spent 18% of the annual cycle (in both spring and autumn) each year. Throughout the annual cycle, 69% of the tracking locations were from outside of the currently protected areas, while none of the critical staging areas enjoyed any form of site protection. We see further future potential to combine avian tracking data and remote-sensing information throughout the annual range of the white-naped crane to restore it and other such species to a more favourable conservation status.

Habitat Quality and Social Behavioral Association Network in a Wintering Waterbirds Community

Migratory waterbirds concentrated in freshwater ecosystems in mosaic environments rely on quality habitats for overwintering. At West Dongting Lake National Nature Reserve (WDLNNR), China, land-use change and hydrology alternation are compounding factors that have affected important wintering areas for migratory waterbirds. Presently, changes in the hydrology and landscape have reshaped natural wintering habitats and their availability, though the impact of hydrological management on habitat selection of wintering waterbirds is largely unknown. In this study, we classified differentially managed habitats and calculated their area using the normalized difference vegetation index (NDVI) to evaluate suitable habitat availability over the study period (2016–2017 and 2017–2018 wintering periods). We then used social behavioral association network (SBAN) model to compare habitat quality through species-species social interactions and species-habitat associations in lakes with different hydrological management. The results indicated that social interactions between and within species structured wintering waterbirds communities, which could be dominated by one or more species, while dominant species control the activities of other co-existing species. Analysis of variance (ANOVA) tests indicated significant differences in SBAN metrics between lakes (p = 0.0237) and habitat (p < 0.0001) levels. Specifically, lakes with managed hydrology were preferred by more species. The managed lakes had better habitat quality in terms of significantly higher habitat areas (p < 0.0001) and lower habitat transitions (p = 0.0113). Collectively, our findings suggest that proper hydrological management can provide continuous availability of quality habitats, especially mudflats and shallow waters, for a stable SBAN to ensure a wintering waterbirds community with more sympatric species in a dynamic environment.

Study of habitat quality assessment using geospatial techniques in Keoladeo National Park, India

Wetlands are one of the most productive ecosystems on the Earth. They are generally considered a transitional state between terrestrial-aquatic habitats and provide numerous vital ecosystem services to mankind. Wetlands are under a tremendous pressure due to growing human interference, urbanization, conventional agriculture, industrial expansions, and overexploitation of ecological services. The Keoladeo National Park (KNP) is a manmade wetland, world heritage site and a designated Ramsar site in India, widely known for its avian biodiversity. Due to insufficient amount of water supply and widespread invasion of Prosopis juliflora, notable spatio-temporal changes are observed in the land cover affecting habitat quality of the park. The present study is designed to highlight the importance of very high-resolution satellite data for characterization of the wetland ecosystem. It assesses the spatio-temporal dynamics of land use/land cover (LULC) and habitat quality, a model built in the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) tool, is utilized to analyze the effect of land cover changes and increase in P. juliflora on habitat quality in the park. The study concludes that drastic changes in LULC and rampant spread of P. juliflora have deteriorated the quality of habitat for bird species. Furthermore, it highlights importance of geospatial tools in mapping, monitoring, and managing wetland ecosystems.

Research on the influence of land use change to habitat of cranes in Shengjin Lake wetland

Shengjin Lake wetland reserve is an important habitat for the winter cranes of our country, and the change of land use structure in the area have had a vital influence on the winter cranes and their habitat. The TM remote sensing images of 1986-2015 years were selected in this paper, and the land use change model and gray relational analysis model were used to analyze the effect of land use degree on the habitat of the winter crane and correlation degree between cranes and land use of Shengjin lake wetland. The land use transformation method was employed to analyze the transfer of the habitat of cranes and the relationship between the size of the cranes habitat and the number of populations. The results showed that the degree of land use change fluctuated greatly in different periods, and comprehensive index of land use degree between 220 and 260, also the land use was based on woodland, grassland, and water and their effect on the habitat was limited; the marsh land had the highest retention rate among the cranes habitat being 34.44%. While the reed flat had the lowest rate, only 15.36%, and the reed breach land was mainly transferred to marsh and dry land, 23.22% and 18.16%, respectively. The mud was mainly transferred to water and farmland, respectively, for 31.79% and 27.75%; except the period from 2011 to 2015, the change of habitat area was basically consistent with the change of the number of cranes.