TY - JOUR

T1 - A multiple-trait analysis of ecohydrological acclimatisation in a dryland phreatophytic shrub

AU - Torres-García, M. Trinidad

AU - Salinas-Bonillo, María J.

AU - Cleverly, Jamie R.

AU - Gisbert, Juan

AU - Pacheco-Romero, Manuel

AU - Cabello, Javier

N1 - Funding Information: This research was done in the framework of the LTSER Platform “The Arid Iberian South East LTSER Platform—Spain (LTER_EU_ES_027)” and supported by the European project LIFE Adaptamed (LIFE14349610 CCA/ES/000612) and the RTI2018-624 102030-B-I00 project of the University of Almería (PPUENTE2020/001). MTT and MP were financially supported by a FPU Predoctoral Fellowship (16/02214 and 14/06782, respectively) of the Spanish Government. MTT also received financial support from the CEI-MAR Foundation (Campus de Excelencia Internacional del Mar). Publisher Copyright: © 2021, The Author(s).

PY - 2021/8/1

Y1 - 2021/8/1

N2 - Water is the main limiting factor for groundwater-dependent ecosystems (GDEs) in drylands. Predicted climate change (precipitation reductions and temperature increases) and anthropogenic activities such as groundwater drawdown jeopardise the functioning of these ecosystems, presenting new challenges for their management. We developed a trait-based analysis to examine the spatiotemporal variability in the ecophysiology of Ziziphus lotus, a long-lived phreatophyte that dominates one of the few terrestrial GDEs of semiarid regions in Europe. We assessed morpho-functional traits and stem water potential along a naturally occurring gradient of depth-to-groundwater (DTGW, 2–25 m) in a coastal aquifer, and throughout the species-growing season. Increasing DTGW and salinity negatively affected photosynthetic and transpiration rates, increasing plant water stress (lower predawn and midday water potential), and positively affected Huber value (sapwood cross-sectional area per leaf area), reducing leaf area and likely, plant hydraulic demand. However, the species showed greater salt-tolerance at shallow depths. Despite groundwater characteristics, higher atmospheric evaporative demand in the study area, which occurred in summer, fostered higher transpiration rates and water stress, and promoted carbon assimilation and water loss more intensively at shallow water tables. This multiple-trait analysis allowed us to identify plant ecophysiological thresholds related to the increase in salinity, but mostly in DTGW (13 m), and in the evaporative demand during the growing season. These findings highlight the existence of tipping points in the functioning of a long-lived phreatophyte in drylands and can contribute to the sustainable management of GDEs in southern Europe, paving the way for further studies on phreatophytic species.

AB - Water is the main limiting factor for groundwater-dependent ecosystems (GDEs) in drylands. Predicted climate change (precipitation reductions and temperature increases) and anthropogenic activities such as groundwater drawdown jeopardise the functioning of these ecosystems, presenting new challenges for their management. We developed a trait-based analysis to examine the spatiotemporal variability in the ecophysiology of Ziziphus lotus, a long-lived phreatophyte that dominates one of the few terrestrial GDEs of semiarid regions in Europe. We assessed morpho-functional traits and stem water potential along a naturally occurring gradient of depth-to-groundwater (DTGW, 2–25 m) in a coastal aquifer, and throughout the species-growing season. Increasing DTGW and salinity negatively affected photosynthetic and transpiration rates, increasing plant water stress (lower predawn and midday water potential), and positively affected Huber value (sapwood cross-sectional area per leaf area), reducing leaf area and likely, plant hydraulic demand. However, the species showed greater salt-tolerance at shallow depths. Despite groundwater characteristics, higher atmospheric evaporative demand in the study area, which occurred in summer, fostered higher transpiration rates and water stress, and promoted carbon assimilation and water loss more intensively at shallow water tables. This multiple-trait analysis allowed us to identify plant ecophysiological thresholds related to the increase in salinity, but mostly in DTGW (13 m), and in the evaporative demand during the growing season. These findings highlight the existence of tipping points in the functioning of a long-lived phreatophyte in drylands and can contribute to the sustainable management of GDEs in southern Europe, paving the way for further studies on phreatophytic species.

KW - Depth-to-groundwater gradient

KW - Ecophysiological threshold

KW - Groundwater salinity

KW - Plant functional traits

KW - Rhamnaceae

KW - Ziziphus lotus

KW - Environmental planning

UR - http://www.scopus.com/inward/record.url?scp=85111573559&partnerID=8YFLogxK

U2 - 10.1007/s00442-021-04993-w

DO - 10.1007/s00442-021-04993-w

M3 - Journal articles

C2 - 34331567

AN - SCOPUS:85111573559

VL - 196

SP - 1179

EP - 1193

JO - Oecologia

JF - Oecologia

SN - 0029-8549

IS - 4

ER -