Abstract
As an internationally important wintering region for waterfowls on the East Asian–Australasian Flyway, the national reserve of China’s East Dongting Lake wetland is abundant in animal and plant resources during winter. The hydrological regimes, as well as vegetation dynamics, in the wetland have experienced substantial changes due to global climate change and anthropogenic disturbances, such as the construction of hydroelectric dams. However, few studies have investigated how the wetland vegetation has changed over time, particularly during the wintering season, and how this has directly affected habitat suitability for migratory waterfowl. Thus, it is necessary to monitor the spatio-temporal dynamics of vegetation in the protected wetland and explore the potential factors that alter it. In this study, the data set of time-series Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) from 2000 to 2018 was used to analyze the seasonal dynamics and interannual trends of vegetation over the wintering period from October to January. The results showed that the average NDVI exhibited an overall increasing trend, with the trend rising slowly in recent years. The largest monthly mean NDVI generally occurred in November, which is pertinent to the quantity of wintering waterfowl in the East Dongting Lake wetland. Meanwhile, the mean NDVI in the wintering season is significantly correlated to temperature and water area, with apparent lagging effects. Long-term stability analysis presented a gradually decreasing pattern from the central body of water to the surrounding area. All analyses will help the government to make appropriate management strategies to protect the habitat of wintering waterfowl in the wetland.
Highlights
Wetland is recognized as one of the most important ecosystems on earth and is generally distributed in the transitional zone between land and water, which has irreplaceable ecological value for protecting species and maintaining biodiversity [1]
In order to study the spatial trends of the vegetation dynamics in the East Dongting Lake wetland during a series of wintering seasons, the linear trend analysis method was used to simulate the changes of the normalized difference vegetation index (NDVI) value for each pixel
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Summary
Wetland is recognized as one of the most important ecosystems on earth and is generally distributed in the transitional zone between land and water, which has irreplaceable ecological value for protecting species and maintaining biodiversity [1]. This is regrettable because the wintering season is a critical period for waterfowl, which influences the water conditions, and thereby the spring departure time and subsequent reproductive success [39] To address this gap in the existent knowledge, the remote sensing and GIS techniques were integrated to address the seasonal and interannual dynamics of spatial vegetation in the East Dongting Lake wetland during the wintering season of waterfowl, from 2000 to 2018, and the interactions between climate change, hydrological conditions, and vegetation dynamics were explored. The NDVI value of each wintering season was calculated from the average value of the four months during October, November, December, and January
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