Dyke demolition led to a sharp decline in waterbird diversity due to
reduction in habitat quality: A case study of Dongting Lake, China
Abstract
Waterbird responses to habitat changes are of great concern in ecology.
Dongting Lake is the second-largest freshwater lake in China, and its
vast wetland area provides an important wintering habitat for migratory
waterbirds of the East Asian–Australasian Flyway. However, lake
reclamation and illegal human-made dykes have degraded the Dongting Lake
wetland area at different degrees in the recent decades, seriously
threatening the ecology of this area. In 2017, to restore the natural
properties of Dongting Lake, the Chinese government completely
demolished 459 dykes and preserved 14 dykes for various purposes
(biodiversity conservation and flood control). However, the direct
impact of dyke demolition on wintering waterbirds has not been
comprehensively assessed. In this study, based on annual
(2013/14–2020/21) waterbird census data, we compared the differences in
species composition of waterbirds in the dyke-demolished and
dyke-preserved areas. The results indicated that waterbird diversity, in
terms of species number, abundance, the proportion of abundance, number
of rare waterbirds species, and exclusive species, was higher in the
dyke preserved areas than in the previously demolished areas. Species
turnover and reordering further identified dynamic differences in the
spatial and temporal distributions of waterbirds. Therefore, we used
long-term habitat data to explore whether habitat changes were
responsible for the changes in waterbirds; the results showed
significantly decreased water and mudflat areas, but a significantly
increased vegetation area in the dyke-demolished areas. The water area
was significantly positively correlated with waterbirds in this habitat.
Compared to the dyke-demolished areas, the stable and suitable habitat
area in the dyke-preserved areas might be closely related to the higher
waterbird diversity. Our study revealed habitat changes in the context
of large-scale dyke demolition in Dongting Lake and demonstrated the
dynamic response of waterbirds to habitat changes.