Abstract
The management of water levels in wetlands is of great importance for the wetland ecosystem, including the conservation and revitalization of plants. However, the water level requirements (WLRs) of wetland plants have not been well investigated. In this study, Typha angustifolia was selected as an experimental plant species. Combining field investigation and simulation experiments, the relationship between the development status of this species and water level fluctuations (WLFs) in different life-history stages were analyzed. The results show that populations in the Yangtze floodplain, China, had two phenotypic forms ‘tall’ and ‘short’, and that these were distributed in lakes with intermittent or quasi-natural fluctuations and reservoir-like fluctuations, respectively. Lakes with high amplitude (>3.2 m) water fluctuations did not contain T. angustifolia. We investigated the distribution and growth of T. angustifolia in lakes of varying hydrology across the Yangtze floodplain, seeking to define its tolerance of water-level fluctuations and submergence at different stages in its life cycle. The upper tolerance limit of static submerged water depth was bounded by 1.5 times the height of plants in the seedling stage, and the upper tolerance limit of the submergence rate in the seedling stage was the average growth rate of seedling, 1.5 cm/d. The plant height had a positive linear correlation with amplitude and water depth from June to July. The autumn biomass was significantly negatively correlated with amplitude and water depth from January to May. This paper is perhaps the first case study on water level fluctuation requirements (WLFRs) of emergent macrophytes. It systematically assessed the WLFRs of T. angustifolia in each life-history stage, and established a comprehensive WLFR conceptual model. The results of this study could provide a quantitative operational basis for the protection and restoration of this species in Yangtze floodplain lakes.
Highlights
Aquatic macrophytes perform essential ecological functions, such as maintaining diversity and purifying water [1]
There are few studies on the water level fluctuation requirements (WLFRs) of herbaceous plants, except for small-scale simulation studies on the effects of water levels and their changes on seedlings of individual species [18,19,20,21,22,23], and the effects of WLFRs on its life-history. To this end, using field investigations and in situ simulation methods, we conducted a systematic study on the WLFRs of aquatic macrophytes in the Yangtze floodplain lakes [24,25,26,27,28], and this paper reports the results of studies on Typha angustifolia
Our results show that the populations of this species in the Yangtze floodplain had two phenotypic forms: ‘tall’ plant form (2.1–3.3 m) and ‘short’ plant form (0.6–1.6 m), which were distributed in lakes with moderate (1.8–3.2 m) and small (
Summary
Aquatic macrophytes perform essential ecological functions, such as maintaining diversity and purifying water [1]. Natural water level fluctuations (WLFs) are of central importance in affecting the diversity of aquatic macrophytes, with plants having morphological, phenological, and life-history strategies [2,3,4]. Due to the impact of water conservancy projects and climate change, many natural WLFs have undergone great changes, leading to a severe decline in aquatic vegetation [5]. Water 2020, 12, 127 necessary to quantify the water level fluctuation requirements (WLFRs) of aquatic macrophytes to carry out environmental water level regulation. WLFRs of aquatic macrophytes are important in environmental flow and past studies have focused on woody plants in the floodplain, especially Populus and Salix in arid and semi-arid regions, where a specific model named the Recruitment Box Model for the seedling stage was established [7,8,9]
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