Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Increased groundwater dependence of riparian vegetation in response to drought

Kui, Li, Williams, Jared, Singer, Michael Bliss ORCID: https://orcid.org/0000-0002-6899-2224, Stella, John C., Kibler, Christopher L., Dawson, Todd E., Rohde, Melissa M., Lambert, Adam M. and Roberts, Dar A. 2025. Increased groundwater dependence of riparian vegetation in response to drought. Ecohydrology 18 (5) , e70060. 10.1002/eco.70060

[thumbnail of Ecohydrology - 2025 - Kui - Increased Groundwater Dependence of Riparian Vegetation in Response to Drought.pdf]
Preview
PDF - Published Version
Available under License Creative Commons Attribution Non-commercial.

Download (1MB) | Preview

Abstract

Riparian ecosystems in drylands face increasing risks from intensifying droughts, which lower water tables, reduce soil moisture and suppress streamflow—threatening vegetation and risking ecosystem collapse. Although riparian vegetation relies on subsurface water, the relative importance of groundwater versus rainfall-infiltrated soil moisture during drought remains unclear. As climate change prolongs drought severity, understanding how plants shift between water sources is key to predicting ecosystem resilience and guiding sustainable groundwater management. We conducted a stable isotope study along the Santa Clara River in southern California (2018–2020) during recovery from a severe (2012–2019) drought. We sampled δ18Op in plant xylem water from four native riparian woody species (Salix exigua, S. laevigata, Populus trichocarpa, P. fremontii) and the non-native grass Arundo donax. Shallow soil moisture and groundwater were sampled to characterize endmember δ18O signatures. Isotope mixing models were developed to track shifts in water source contributions for each species over three growing seasons. Riparian plants showed opportunistic water use, relying on shallow soil moisture during wet periods and shifting to groundwater during droughts. Native taxa including Populus and Salix species increased groundwater use by up to 60% during drought, reflecting hydraulic flexibility and drought tolerance. In contrast, the invasive A. donax depended on shallow soil moisture for 64–86% of its water under all conditions. These findings underscore the importance of quantifying species- and site-specific groundwater use. Incorporating such ecological insights into groundwater sustainability planning will be critical for protecting riparian vegetation and maintaining ecosystem function in a changing climate.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Schools > Earth and Environmental Sciences
Publisher: Wiley
ISSN: 1936-0584
Date of First Compliant Deposit: 10 June 2025
Date of Acceptance: 26 May 2025
Last Modified: 29 Jul 2025 10:30
URI: https://orca.cardiff.ac.uk/id/eprint/178979

Actions (repository staff only)

Edit Item Edit Item

Downloads

Downloads per month over past year

View more statistics