Colonisation of terrestrial vegetation in an intermittent river: Diversity responses to seasonal drying

Abstract

Intermittent rivers are dynamic ecosystems that experience a predictable or unpredictable loss of surface water and are characterised by changing lotic, lentic (ponding) and dry habitats. Plant communities colonising dry channels during the desiccation stage can be diverse, abundant and differ in their tolerances to water availability and habitat conditions. This study examines the colonisation of terrestrial vegetation in two intermittent rivers in the United Kingdom, and whether terrestrial plant taxonomic richness and functional diversity increase during the dry phase. Six reaches were surveyed for terrestrial plants during the dry phase over a standard 100 m length every month from April to October 2021. We found the channel and bank taxonomic richness increased with drying duration. Functional traits of vegetation height, clonality, clonality richness and Ellenberg's value of light moisture also increased with stream desiccation. Bed sediment conditions (the proportion of sand and gravel) and the 12-month antecedent percentage of zero flow days were the key drivers of plant community composition. We believe plant propagules from the riparian zone and channel vegetation on topographic high points in the channel aided plant colonisation of the riverbed once flow ceased. Past research may have underestimated the biodiversity value of intermittent rivers by failing to include the ecological importance of plants during the dry phase. Information on plant diversity of the dry phase is important to determine the overall biodiversity of intermittent rivers for their long-term conservation and management.

River regulation effects on zooplankton community assembly: Implications for arid river restoration and conservation

“…Water replenishment is an essential and effective method for river flow recovery, community assembly, nutrient diffusion, and living river reconstruction (Bozelli et al, 2015; Owusu et al, 2021; Pedroli et al, 2002). Scientific planning and management of water flow timing, magnitude, frequency, and duration are essential for the sustainability of limited water resources (Milner et al, 2023; Phelan et al, 2017; Zhao et al, 2020). Continuous river flow provides an effective corridor for the communication of aquatic organisms, promotes the diffusion and exchange of nutrients, and sustains living river systems (Bozelli et al, 2015; Pedroli et al, 2002).…”

“…Failure to consider the ecological functions of aquatic organisms has led to ecosystem equilibrium disruption and ecosystem loss in natural water bodies worldwide (Chilton et al, 2021; Lytle & Poff, 2004; Mitrovic et al, 2003). Given the challenges of water scarcity in many global regions, it is necessary to evaluate the responses of aquatic communities to flow changes and fill gaps in understanding of how natural flow regimes have changed river dynamics and overall ecosystem functions (Lee et al, 2023; Milner et al, 2023; Patil et al, 2022).…”

“…magnitude, frequency, and duration are essential for the sustainability of limited water resources (Milner et al, 2023;Phelan et al, 2017;Zhao et al, 2020). Continuous river flow provides an effective corridor for the communication of aquatic organisms, promotes the diffusion and exchange of nutrients, and sustains living river systems (Bozelli et al, 2015;Pedroli et al, 2002).…”