Heatwaves are becoming more intense and frequent. Plant photosystem thermal thresholds can vary with species, but also shift in response to environmental triggers. Both upper and lower thresholds can acclimate to repeated heatwaves through ecological stress memory, where prior exposure primes them for subsequent events. The extent to which acclimation to repeated heat stress events varies among environmental origin and/or species is unknown. Different acclimation strategies might reflect biome of origin, or may be species-specific.

For 12 species from two contrasting biomes – extreme desert and benign coastal temperate – we investigated responses to two simulated heatwaves, via shifts in upper and lower critical temperatures of photosystem II, and the difference between these thresholds, thermal tolerance breadth (TTB).

Biome of origin had no effect on thermal tolerance. Observed differences among species following heat events suggested two possible acclimatory strategies. In some cases, species increased thermal thresholds during the first heatwave, but at the cost of reduced thermal tolerance during the second heatwave, a sprinter strategy. Other species acclimated to the first heatwave and further increased thermal tolerance to a second heatwave, indicative of ecological stress memory, a marathoner strategy.

Synthesis: These among-species responses to heatwaves could suggest distinct vulnerabilities and resilience to repeat heat stress events, with some species having limited capacity to tolerate consecutive heatwaves, possibly as the cost of acclimation is too great, with other species having the advantage of increased tolerance via stress memory, helping them survive future stress, at least in the short-term.

Native Australian seedlings exhibit novel strategies to acclimate to repeated heatwave events

Contains 15 files:

(1) Analysis - R scripts required to replicate analysis and figures in the manuscript and supplementary material:
DRYAD biome and species lmer models.R
DRYAD Delta models.R
DRYAD Figure 2.R
DRYAD supp.R

(2) Datasets (11 files total):

dfcold.csv
dfhot.csv
dfTTB.csv

For analysis of effect of treatment and time period on seedling tcrit_hot, tcrit_cold and thermal tolerance breadth

Columns:

stage - the time period of when the measurement was taken; 1,2,3,4
biome - desert (extreme), coastal temperate (benign)
species - Acacia longifolia, Acacia salicina, Acacia victoriae, Banksia integrifolia, Capparis mitchellii, Carex appressa, Casuarina pauper, Eucalyptus largiflorens, Flindersia maculosa, Lomandra longifolia, Melaleuca hypericifolia, Pittosporum undulatum
treatment - 0_HW, control; 1_HW, one heatwave; 2_HW, two heatwaves
block_rep - replicate; 1, 2, 3, 4, 5
ID - a unique identifier for each leaf
wkend - whether the plants experienced a two-day period of heat
delay - whether the plants experienced a delay in watering with potential water stress
tcrit - the inflection point between the fast and slow rise phases of the T- F0 curve (Knight and Ackerly 2002)

delta_slopes.csv

For analysis comparing the slopes of the sprinters and marathoners’ thermal tolerance breadth

Columns:

species - Acacia longifolia, Acacia salicina, Acacia victoriae, Banksia integrifolia, Capparis mitchellii, Carex appressa, Casuarina pauper, Eucalyptus largiflorens, Flindersia maculosa, Lomandra longifolia, Melaleuca hypericifolia, Pittosporum undulatum
biome - desert (extreme), coastal temperate (benign)
block - replicate; 1, 2, 3, 4, 5
slope - the calculated slope between stage 1 and stage 3
group - marathoner; sprinter

mcoldHWsum.csv
mcoldRECsum.csv
mhotHWsum.csv
mhotRECsum.csv
TTBHWsum.csv
TTBRECsum.csv

For graphing the sprinters vs. marathoners groups
Columns:

species- Acacia longifolia, Acacia salicina, Acacia victoriae, Banksia integrifolia, Capparis mitchellii, Carex appressa, Casuarina pauper, Eucalyptus largiflorens, Flindersia maculosa, Lomandra longifolia, Melaleuca hypericifolia, Pittosporum undulatum
biome - desert (extreme), coastal temperate (benign)
stage - the time period of when the measurement was taken; 1,2,3,4
mTTB - mean thermal tolerance breadth
sdTTB - standard deviation of thermal tolerance breadth
nTTB - number of replicates
seTTB - standard error of thermal tolerance breadth

DRYAD_supp.csv

For calculating the mean of the control vs. the treatment at each stage, for each species

test - which measurement was taken; tcrit hot, tcrit cold, ttb
stage - the time period of when the measurement was taken; 1,2,3,4
biome - desert (extreme), coastal temperate (benign)
species - Acacia longifolia, Acacia salicina, Acacia victoriae, Banksia integrifolia, Capparis mitchellii, Carex appressa, Casuarina pauper, Eucalyptus largiflorens, Flindersia maculosa, Lomandra longifolia, Melaleuca hypericifolia, Pittosporum undulatum
treatment - 0_HW, control; 1_HW, one heatwave; 2_HW, two heatwaves
block_rep - replicate; 1, 2, 3, 4, 5
ID - a unique identifier for each leaf
wkend - whether the plants experienced a two-day period of heat
delay - whether the plants experienced a delay in watering with potential water stress
tcrit - the inflection point between the fast and slow rise phases of the T- F0 curve (Knight and Ackerly 2002)
ttb - thermal tolerance breadth measurement

Native Australian seedlings exhibit novel strategies to acclimate to repeated heatwave events

Data files

Abstract

Native Australian seedlings exhibit novel strategies to acclimate to repeated heatwave events

Native Australian seedlings exhibit novel strategies to acclimate to repeated heatwave events

Data files

Abstract

README

Native Australian seedlings exhibit novel strategies to acclimate to repeated heatwave events

Works referencing this dataset