Zolfaghar, Sepideh, Villalobos-vega, Randol, Cleverly, James, and Eamus, Derek (2015) Co-ordination among leaf water relations and xylem vulnerability to embolism o fEucalyptus trees growing along a depth-to-groundwater gradient. Tree Physiology, 35 (7). pp. 732-743.

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Abstract

The importance of groundwater resources in arid and semi-arid areas for plant survival is well documented. However, there have been few studies examining the importance and impacts of groundwater availability in mesic environments. The aim of this study was to determine how depth-to-groundwater (DGW) impacts on leaf water relations, leaf structure and branch xylem vulnerability to embolism in a mesic environment. We hypothesize that increasing DGW results in increased resistance to drought stress and that this will be manifested across leaf and branch attributes pertaining to water relations. We further investigate whether there is co-ordination across leaf and branch-scale level responses to increased DGW. Four species were used in this study: Eucalyptus globoidea Blakely, E. piperita Sm., E. sclerophylla (Blakely) L.A.S.Johnson & Blaxell and E. sieberi L.A.S.Johnson. Six sites were chosen along an 11 km transect to span a range of average DGW: 2.4, 4.3, 9.8, 13, 16.3 and 37.5 m. Leaf water relations of trees showed less sensitivity to drought stress as DGW increased. This was reflected in significantly lower leaf turgor loss point and maximum osmotic potential, increased maximum turgor and a reduced leaf relative water content as DGW increased. At shallow DGW sites, minimum diurnal leaf water potentials were generally more negative than leaf water potential at zero turgor, but the reverse was observed at deep sites, indicating a larger growth potential safety margin at deep sites compared with shallow sites. Leaf cell wall elasticity varied independently of DGW. Xylem vulnerability to embolism was quantified as the water potential associated with 50% loss of conductance (P50). In both summer and winter P50 was significantly and negatively correlated with DGW. Co-ordination between leaf- and branch-level responses to increase in DGW was apparent, which strongly supports the conclusion that groundwater supply influenced woodland structure and functional behaviour.

Item ID:	73506
Item Type:	Article (Research - C1)
ISSN:	1758-4469
Copyright Information:	© The Author 2015. Published by Oxford University Press. All rights reserved.
Date Deposited:	19 Dec 2023 01:32
FoR Codes:	31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310806 Plant physiology @ 50% 41 ENVIRONMENTAL SCIENCES > 4102 Ecological applications > 410203 Ecosystem function @ 25% 37 EARTH SCIENCES > 3707 Hydrology > 370702 Ecohydrology @ 25%
SEO Codes:	18 ENVIRONMENTAL MANAGEMENT > 1806 Terrestrial systems and management > 180601 Assessment and management of terrestrial ecosystems @ 100%
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