Can hydrological niche segregation explain species distributions in an aquifer-dependent wetland?
type: CreativeWork
description: Aim: To investigate post-fire succession in fynbos wetland plant communities, test whether these species segregate along fine-scale hydrological gradients and to identify species potentially most sensitive to groundwater abstraction. Intro: Hydrological gradients, which form between permanently inundated wetlands and adjacent dry habitats, are key drivers of vegetation community composition and structure, promoting opportunities for adaptive speciation and community coexistence. In the seasonally arid fynbos region of South Africa, the occurrence of permanently inundated, groundwater-fed wetlands suggests that fine-scale hydrological gradients may significantly shape floristic diversity in this region. The extent to which fine-scale hydrological gradients influence community composition and species segregation requires further testing in fynbos but has important implications for understanding the potential impacts of groundwater abstraction in these fire-prone systems as well as identifying potentially sensitive species. Methods: I analyzed plant community composition and abundance data, along with soil volumetric water content collected across three transects in an aquifer-fed wetland, from 2011 to 2022. Non-parametric multivariate tests were used to quantify spatial and temporal changes in community composition, highlighting general patterns of community clustering across transects and changes related to post-fire succession. The hydrological niche space was quantified across an aquifer-dependent wetland by representing soil moisture data along two hydrological axes: the sum of exceedance values for flooding (SEVa) and drought (SEVd). Using a subset of persistent species, species locations were fitted to these hydrological axes based on their proximity to soil moisture probes. Species were ranked in accordance with their position on this gradient, indicating a preference for flooded or drier sites on the wetland. Results: Successional changes were observed in the …
abstract: Aim: To investigate post-fire succession in fynbos wetland plant communities, test whether these species segregate along fine-scale hydrological gradients and to identify species potentially most sensitive to groundwater abstraction. Intro: Hydrological gradients, which form between permanently inundated wetlands and adjacent dry habitats, are key drivers of vegetation community composition and structure, promoting opportunities for adaptive speciation and community coexistence. In the seasonally arid fynbos region of South Africa, the occurrence of permanently inundated, groundwater-fed wetlands suggests that fine-scale hydrological gradients may significantly shape floristic diversity in this region. The extent to which fine-scale hydrological gradients influence community composition and species segregation requires further testing in fynbos but has important implications for understanding the potential impacts of groundwater abstraction in these fire-prone systems as well as identifying potentially sensitive species. Methods: I analyzed plant community composition and abundance data, along with soil volumetric water content collected across three transects in an aquifer-fed wetland, from 2011 to 2022. Non-parametric multivariate tests were used to quantify spatial and temporal changes in community composition, highlighting general patterns of community clustering across transects and changes related to post-fire succession. The hydrological niche space was quantified across an aquifer-dependent wetland by representing soil moisture data along two hydrological axes: the sum of exceedance values for flooding (SEVa) and drought (SEVd). Using a subset of persistent species, species locations were fitted to these hydrological axes based on their proximity to soil moisture probes. Species were ranked in accordance with their position on this gradient, indicating a preference for flooded or drier sites on the wetland. Results: Successional changes were observed in the …
author: Havhi, Mpho
language: en
keywords: Hydrological gradients, South Africa
date published: 2025
date modified: 2026-07-22T22:23:19Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Biological Sciences

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/42298