Foliar plasticity related to gradients of heat and drought stress across crown orientations in three Mediterranean Quercus species

Abstract

Studies on plasticity at the level of a single individual plant provide indispensable information to predict leaf responses to climate change, because they allow better identification of the environmental factors that determine differences in leaf traits in the absence of genetic differences. Most of these studies have focused on the responses of leaf traits to variations in the light environment along vertical gradients, thus paying less attention to possible differences in the intensity of water stress among canopy orientations. In this paper, we analyzed the differences in leaf traits traditionally associated with changes in the intensity of water stress between east and west crown orientations in three Quercus species. The leaves facing west experienced similar solar radiation levels but higher maximum temperatures and lower daily minimum water potentials than those of the east orientation. In response to these differences, the leaves of the west orientation showed smaller size and less chlorophyll concentration, higher percentage of palisade tissue and higher density of stomata and trichomes. These responses would confirm the role of such traits in the tolerance to water stress and control of water losses by transpiration. For all traits, the species with the longest leaf life span exhibited the greatest plasticity between orientations. By contrast, no differences between canopy positions were observed for leaf thickness, leaf mass per unit area and venation patterns.

Chemical Composition of Cuticular Waxes and Pigments and Morphology of Leaves of Quercus suber Trees of Different Provenance

“…The cork oak leaves in the trees of all the provenances showed a clear schlerophytic character ( Figure 1 and Figure 2 ) and their morphological features ( Table 1 ) were within the range of values reported for the species. Leaf sizes (4.6–6.8 cm 2 ) were similar to those reported by Mediavilla et al [ 28 ] for Q. suber leaves taken from different orientations in the canopy (5.5–7.4 cm 2 ) and the 7.1 cm 2 reported by Prats et al [ 20 ]. The specific leaf area values (55.6–67.8 cm 2 /g) were of the same order of magnitude as those obtained in adult leaves of Q. suber growing under contrasting environments and located in different positions and orientations of the canopy (50.0 to 126.0 cm 2 /g) [ 28 , 29 , 30 , 31 , 32 ].…”

“…In the present study, the observed amounts of the total chlorophyll, expressed per unit of leaf area or per unit of dry weight ( Table 1 ), were consistent with those reported in the available studies for Q. suber , for example, the results of Ramírez-Valiente et al [ 30 ] for leaves of open-pollinated trees from populations in Morocco, Portugal and Spain (2.68 mg/g, 2.64 mg/g and 2.74 mg/g respectively) and 55.7 µg/cm 2 and 56.0 µg/cm 2 total chlorophyll in sun and shade leaves of 40-year-old Q. suber trees [ 40 ]. Mediavilla et al [ 28 ] also observed that the chlorophyll content differed among canopy orientations, with lower values on the west side (80 vs. 110 µg/cm 2 ), probably due to a direct effect of excess radiation at the time of the day with highest leaf temperatures and lowest water potential on the west facing leaves.…”

Lifetime genealogical divergence within plants leads to epigenetic mosaicism in the shrub Lavandula latifolia (Lamiaceae)

“…Depending on its magnitude and spatio‐temporal patterning, this subindividual phenotypic variance can have multiple ecological effects. These include optimizing the exploitation of limiting resources such as light, water or nitrogen (Osada et al ., 2014; Ponce‐Bautista et al ., 2017; Mediavilla et al ., 2019), altering the outcome of interactions with animals (Sobral et al ., 2013, 2014; Shimada et al ., 2015; Wetzel et al ., 2016), driving selection on reproductive traits (Austen et al ., 2015; Dai et al ., 2016; Arceo‐Gómez et al ., 2017; Kulbaba et al ., 2017), and enhancing tolerance of environmental unpredictability (Tíscar Oliver & Lucas Borja, 2010; Hidalgo et al ., 2016). Because of these ecological effects, subindividual variability can eventually influence the fitness of individuals and become itself a target for natural selection, since plants not only have characteristic trait means but also characteristic trait variances and spatio‐temporal patterns of subindividual heterogeneity (Herrera, 2009, 2017; Kulbaba et al ., 2017; Harder et al ., 2019).…”

Lifetime genealogical divergence within plants leads to epigenetic mosaicism in the long-lived shrubLavandula latifolia(Lamiaceae)

“…Depending on its magnitude and spatio-temporal patterning, this subindividual phenotypic variance can have multiple ecological effects. These include optimizing the exploitation of limiting resources such as light, water or nitrogen (Osada et al, 2014;Ponce-Bautista et al, 2017;Mediavilla et al, 2019), altering the outcome of . CC-BY-NC-ND 4.0 International license perpetuity.…”

“…Depending on its magnitude and spatio-temporal patterning, this subindividual phenotypic variance can have multiple ecological effects. These include optimizing the exploitation of limiting resources such as light, water or nitrogen (Osada et al ., 2014; Ponce-Bautista et al ., 2017; Mediavilla et al ., 2019), altering the outcome of interactions with animals (Sobral et al ., 2013, 2014; Shimada et al ., 2015; Wetzel et al ., 2016), driving selection on reproductive traits (Austen et al ., 2015; Dai et al ., 2016; Arceo-Gómez et al ., 2017; Kulbaba et al ., 2017), and enhancing tolerance of environmental unpredictability (Tíscar Oliver & Lucas Borja, 2010; Hidalgo et al ., 2016). Because of these ecological effects, subindividual variability can eventually influence the fitness of individuals and become itself a target for natural selection, since plants not only have characteristic trait means but also characteristic trait variances and spatio-temporal patterns of subindividual heterogeneity (Herrera, 2009, 2017; Kulbaba et al ., 2017; Harder et al ., 2019).…”