| Popis: |
Djoudj National Bird Sanctuary, as a UNESCO natural heritage site, is a critical habitat for migratory birds along the East Atlantic Flyway (EAF). The bird habitat has undergone the dramatic variations of the Land Use and Land Cover Change (LUCC) under the influence of climate change and human activities, posing a serious threat to the survival of migratory birds along the EAF. In order to explore the spatio-temporal variations of LUCC in Djoudj National Bird Sanctuary during 1984 to 2023, this study employs multitemporal satellite image data to extract the LUCC of this heritage site and adjacent region, and comprehensively analyze the impact factors induced the variations of LUCC. Our results show that it went through two stages of the significant change in LUCC over the past 40 years. The first stage of significant change is from 1984 to 1990, when the areas of soil land and saline soil land had largely transformed into water bodies, vegetation, and wetlands. The areas of soil and saline soil land were decreased by 28.86% and 8.96%, respectively. Meanwhile, the areas of wetland, water body and vegetation increased to 30.53%, 4.92% and 2.37%, separately. The second stage of significant change in LUCC is from 2000 to 2010, while the area of vegetation (including the invasive plants) increased significantly to 54.02%, and the areas of water bodies, wetlands, and saline soil areas decreased to 6.19%, 10.37%, and 10.05% respectively. At the same time, the area of agricultural land around the heritage site rapidly increased from 13.292 km2 in 2006 to 114.2603 km2 in 2023. These significant variations of LUCC led to a decrease in the number of migratory birds, and the Djoudj National Bird Sanctuary had been listed as List of World Heritage in Danger twice by the World Heritage Committee. The major factors contributing to these significant changes in LUCC are mainly caused by human activities, such as the construction of the Diama Dam and improper use of upstream of the dam, as well as the expansion of agricultural land around the heritage site. Thus, we suggest that the heritage administrative authorities should make relevant measures to scientifically minimize the impact of human activities on ecosystem of the heritage site, and conduct regularly an integrated “space-to-ground” monitoring and assessment of water usage of the dam, controlling of invasive plants, strictly regulating the expansion of agricultural land within the heritage site and adjacent region. |
