Abstract
Wet meadows are one of the most important ecological components in floodplain, and are among the most dynamic ecosystems. Understanding the development of wet meadows and contributing environmental factors can provide better support for wetland management. Carex meadows in East Dongting Lake National Nature Reserve (EDLNNR) provide vital wintering ground for thousands of migratory waterbirds, and their ecological functions are under threated due to hydrological alternation. We measured wet meadow expansion in EDLNNR from 1989 to 2014, and explored its responses to hydrological and climatic factors within the generalised additive models (GAM) framework. We found an overall expansion of wet meadows over the study period. However, in contrast to many previous studies, our results showed that water level fluctuations at the hydrologic indicator site had only limited impacts on their development. Instead, sampling year, timing of water level recession, and local rainfall exerted significant effects. The effects of sampling year reflected the changes in sedimentation within Dongting Lake; and effects of timing of water withdrawal might be explained by the life history of the dominant sedge species. Our study suggested that the impacts of large scale hydrological alternation on vegetation may operate indirectly through its effects on sediment balance.
Highlights
Wet meadows are one of the most important ecological components in floodplain, and are among the most dynamic ecosystems
A general increasing trend was found in wet meadows distribution in EDTNNR during the study period
This result is consistent with the findings from previous researches[25,26]. These previous studies considered that the decreased water level due to the operation of the Three Gorges Dam was the main factor contributing to the expansion of wet meadows
Summary
Wet meadows are one of the most important ecological components in floodplain, and are among the most dynamic ecosystems. Wet meadows are one of the most important ecological components in floodplain systems for their biological diversity[1] and the ecosystem services they provide, including nutrient cycling, pollution removal, and carbon sequestration[2] These values have been degraded or destroyed in recent decades, mainly due to land use intensification[3] and hydrological alternation[4]. The Dongting Lake plays a vital role in flood controlling and climate regulation in the middle and lower reach of Yangtze River basin due to its large surface are and storage capacity[24] It provides numerous habitats for floras and faunas at local, regional, and global scales as it encompasses various wetland types, such as wet meadows, shadow waters, and mudflats[6]. More than 90% of the East Asian population of the threatened Lesser White-fronted Goose (Anser erythropus) overwinter at the EDL, and foraging extensively on wet meadows[8]
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