Abstract Detail

Ecophysiology

Givnish, Thomas [1], Smith, Duncan D [2], Salvi, Amanda [3], Buckley, Thomas N [4], Adams, Mark A [5], McCulloh, Kate [6].

Integrated adaptations to moisture supply and whole-plant growth in ten Eucalyptus species dominating different portions of a climatic moisture gradient in Victoria, Australia.

Terrestrial plants face a fundamental trade-off: any aspect of leaf structure that tends to increase the inward diffusion of CO₂ to enhance photosynthesis will also increase the outward diffusion of water vapor, increasing the potential for tissue desiccation, lower physiological performance, and plant death. Economic theory predicts that several photosynthetic, hydraulic, and allocational traits should vary in concerted fashion with relative moisture supply in order to maximize plant growth and competitive ability. We are testing these hypotheses and the possibility that such adaptations help determine sub-continental species distributions in ten Eucalyptus species, stratified phylogenetically and by dominance of succession geographic bands in the ratio of rainfall to pan evaporation (P/E_p) in Victoria, Australia. We are scoring seedling survival, growth, and variation in 20 traits in 10 species grown in four common gardens along this gradient in areas that support tall temperate rain forests to arid mallee, with annual rainfall varying from 1350 to 290 mm/yr, and P/E_p varying 8.5-fold, from 1.35 to 0.16. Here we report on initial outcomes from the first of three experiments in our four common gardens across a climatic gradient, and analyze trait x trait and trait x environment relationships in an explicitly phylogenetic framework. Among many parameters studied, SLA, Amax, height growth, and RGR for plant mass all increase with native P/E_p, while leaf thickness and wood density decline. Analyses of plasticity show substantial increases in SLA, Amax, and leaf absorptance with treatment P/E_p, but little variation in leaf thickness or wood density, and rather limited cross-over in species expression of each of these traits. Our overall research program is unusual for studying adaptation to moisture supply, in terms of the range of traits whose adaptation and integration is being examined, for the use of common gardens to test for cross-over in height growth as support for adaptation and a potential force shaping species distributions, and for the use of growth models to identify key traits and trait aggregates affecting growth.

1 - University Of Wisconsin-Madison, Department Of Botany, Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, United States
2 - University of Wisconsin-Madison, Department of Botany, 430 Lincoln Drive, Madison, WI, 53706, United States
3 - University Of Wisconsin-Madison, Department Of Botany, 322 Birge Hall 430 Lincoln Drive, Madison, WI, 53706, United States
4 - University of California at Davis, Plant Science, 206 Natchez Trace, Davis, CA, 95616, USA
5 - Swinburne University of Technology, School of Science, Melbourne, Victoria, Australia
6 - Department Of Botany, 430 Lincoln Dr, Madison, WI, 53706, United States

Keywords:
photosynthesis
Leaf hydraulics
multiple common gardens
Plasticity
adaptation
ecophysiology
ecological distributions.

Presentation Type: Oral Paper
Session: ECOPH2, Ecophysiology II
Location: San Pedro 2/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 1:30 PM
Number: ECOPH2001
Abstract ID:841
Candidate for Awards:None