Invasive smooth cordgrass (Spartina alterniflora) has been expanding rapidly through the coastal wetlands of eastern China and these changes negatively affect local birds. In the Dafeng Milu National Nature Reserve (henceforth referred to as DMNNR), rapid degradation of spartina occurs after an increase in milu (Elaphures davidianus; hereafter elk) numbers and ecological hydrological engineering. We evaluated the impact of such degradation on the abundance and species diversity of birds in the DMNNR during 2017–2021. We found that the area covered by S. alterniflora decreased significantly in the study area at a rate of 310 ha per year and by 62% during 2017–2021 (p < 0.01). With this decrease in the S. alterniflora area, the species richness and abundance of birds first increased and then decreased. Songbird density clearly decreased but species richness did not significantly do so. This research demonstrated that during the initial stages of vegetation degradation, there was a positive effect on bird diversity. With the increasing vegetation degradation increases, both songbirds and waterbirds experience negative impacts. The DMNNR is an important stopover site for waterbirds in the East Asian–Australasian Flyway, and additional measures are needed to control vegetation degradation and to restore the native habitats for birds.
After the smooth cordgrass Spartina alterniflora invaded coastal China, native birds started avoiding the green desert, and bird diversity declined. After many years, a few passerine birds began to enter and use smooth cordgrass, but only birds with a nonspecialised habitat. In this study, we found that a native reed‐specific bird, the parrotbill Calamornis heudei, flocked and sang in a smooth cordgrass habitat throughout the overwintering period near Sheyang Port in Yancheng, Jiangsu Province. This observation suggests that native obligate birds may be forced to adapt to exotic smooth cordgrass habitats after long‐term coexistence, which would, obviously, affect the distribution, feeding and reproduction of birds. The concern is that this could be an ecological trap, leading to unknown consequences. More research is required to examine the process occurring along the Chinese coast.
The western population of the red‐crowned crane Grus japonensis in mainland China has been decreasing in the past few decades and wild population enhancement programmes have been launched in this country. First, 14 captive‐bred red‐crowned cranes were released into the core area of Yancheng National Nature Reserve for Rare Birds (YNNR), one of the most important wintering areas of this species, in 2013 (seven individuals) and 2015 (seven individuals) and then 8 more captive‐bred cranes were released into YNNR from February 2022 to February 2023. We used satellite positioning and drone monitoring to study the status of released cranes. The results showed that two individuals (No. BJZ001 and BJZ008) from the first group of released cranes were found breeding in 6 of 7 years in the YNNR from 2017 to 2023. Three individuals (No. WNNR022, WNNR025 and WNNR026) from the second group of released cranes were recorded breeding in YNNR in 2023. All released cranes lived in the YNNR year round and did not migrate with wild cranes. Raccoon dogs, Nyctereutes procyonoides, were first recorded as red‐crowned crane nest predators in the YNNR. Although these released cranes breed successfully in the YNNR, nestlings might face the threat of predators in non‐traditional breeding areas. Further research is needed to determine whether offsprings of released individuals migrate with wild cranes and if breeding in their original wintering grounds is truly beneficial for population growth.
8 December 2024 in Global Ecology and Conservation
Bird diversity has declined as native birds have avoided using the green desert after the smooth cordgrass Spartina alterniflora invaded coastal China. After many years of coexistence, a few passerine birds began to enter and use Smooth Cordgrass to breed, but only birds of nonspecialised habitat. In this study, we first found that a native reed-specific bird, the Parrotbill Calamornis heudei, flocked and sang in a Smooth Cordgrass habitat near Sheyang Port in Yancheng, Jiangsu Province. This phenomenon indicates that native obligate birds may be forced to adapt to exotic Smooth Cordgrass habitats after long-term coexistence; obviously, the distribution, feeding and reproduction of birds would be affected, which may lead to unknown ecological consequences. We suggest that more research attention should be given to this process occurring along the Chinese coast.
There is currently no consistent conclusion about the impacts of global Spartina alterniflora invasion on intertidal macrobenthic communities, and the impact mechanisms are also not clear enough due to the limitations in study sites and duration. Here, after collecting and extracting 2110 data from 96 studies around the world, we utilized hierarchical meta-analysis to quantify the impacts of Spartina alterniflora invasion on intertidal macrobenthic communities, and systematically analyzed and summarized the factors influencing invasion results for the first time. The results showed that the invasion of Spartina alterniflora generally has a negative impact on macrobenthic communities, but has a positive impact on species number and richness index of microbenthic communities. The pattern of influence strongly depends on the native habitat, invasion duration, average annual temperature, sediment type and tide level, which indicates that Spartina alterniflora affects macrobenthic communities by altering the external environment of the invaded area, and the habitat heterogeneity in different intertidal zones also leads to diverse impacts of Spartina alterniflora invasion on macrobenthic communities. Our study provides important insights for a comprehensive understanding of biological invasions and offers new perspectives for future ecological restoration in intertidal zones.