Changes in Foliar Functional Traits of S. pyrenaicus subsp. carpetanus under the Ongoing Climate Change: A Retrospective Survey

Abstract

The sensitivity of stomatal behavior and patterning (i.e., distribution, density, size) to environmental stimuli, renders them crucial for defining the physiological performance of leaves. Thus, assessing long-term modifications in stomatal traits in conserved specimens arises as a valuable eco-physiological approach to predict how the rising trend of warmer, drier summers could affect plant fitness; particularly in mountain areas already experiencing climate aggravation and lacking the related monitoring schemes like Mediterranean high-mountains. Variations in foliar and stomatal traits were studied in conserved specimens of Senecio pyrenaicus subsp. carpetanus from Sierra de Guadarrama over the past 71 years. Our findings revealed decreasing trends in leaf width, stomatal size, and increasing tendency in stomatal density, all correlated with the recent 30-year climate exacerbation in these mountains. This evidenced a positive selection favoring traits that allow safeguarding plant performance under drier, hotter weather conditions. The significant relation between stomatal traits and climatic variables upholds the role of stomatal patterning in sensing environmental cues in this species, feasibly optimizing physiological responses involved in the growth–water loss trade-off. The transition to smaller, densely packed stomata observed in recent decades could indicate local-adaptive plasticity in this species, enhancing stomatal response, as coarser environmental conditions take place in Sierra de Guadarrama.

Diversity and mean specific leaf area of Mediterranean woody vegetation changes in response to summer drought across a double stress gradient: The role of phenotypic plasticity

“…The summer drought has implied a generalised decrease in SLA CWM across the gradient, a result that we expected to find and that is consistent with the results of previous research where a decrease in SLA is observed in dry months (Garnier et al, 2001;Rossatto et al, 2013) or over several decades of increased aridity Magaña Ugarte et al, 2020). The decrease in SLA in our study is mainly due to an increase in leaf weight that may come from two distinct but complementary acclimation processes: some shrubs lose part of their leaves before the summer drought (Simões et al, 2008) and could be expected to lose the leaves less adapted to summer conditions (intracohort selection), that is those with higher SLA.…”

Assessing the Role of Selected Osmolytes in Mediterranean High-Mountain Specialists

“…The suggested robustness in S. carpetanus may be linked to long-term feedbacks driven by long-standing environmental coarsening in this mountain range. These feedbacks may have caused the selection of functional traits that confer greater drought endurance, such as smaller leaf areas to reduce the ratio of hydraulic demand to supply (Magaña Ugarte et al, 2020). In F. curvifolia, the inferred robustness could be attributed to its strong competitiveness for resources and dominance in these xerophytic pastures (Pescador et al, 2014).…”

Photoprotective Strategies in Mediterranean High-Mountain Grasslands

“…Conversely, and akin to the findings by Buchner et al [12] in Senecio incanus, our results in S. carpetanus and F. curvifolia indicate the xanthophyll cycle operates in response to the daily thermal and light intensity variations in these species, rather than in response to year-to-year climate wavering (Figures 2 and 3). The latter is associated with superior life strategies and functional trait differentiation in S. carpetanus and F. curvifolia, resulting from the selection over time of functional traits granting greater tolerance to the coarsening climate in this mountain range and the firm competitiveness and dominance in these xerophytic pastures, respectively [28,44].…”

“…The occurrence and the severity of summer stress underline the more challenging conditions constraining plant life in Mediterranean high-mountains [2,27]. Furthermore, the marked interannual climate variability characteristic of these habitats, coupled with the higher frequency and severity of combined drought and heat episodes witnessed in recent years [28,29], adds further pressures to the establishment and survival of Mediterranean high-mountain plants [30,31].…”