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

Abstract

Aim: Many aspects of vegetation response to increased drought remain uncertain but it is expected that phenotypic plasticity may be key to early adaptation of plants to environmental stress. In this work we observe the response of specific leaf area (SLA) of woody shrub vegetation to the summer drought typical of the Mediterranean climate. In addition, to observe the possible interaction between the impact of drought and the environmental characteristics of the ecosystems, communities from different edaphic and structural contexts distributed along the double stress gradient of the Mediterranean mountains (high temperature and low precipitation at low elevation; low temperature and high irradiation at high elevation) have been analysed. Location: Central Mountain range of the Iberian Peninsula. Methods: Along the entire altitudinal gradient, 33 shrub communities belonging to different habitat typologies (shrublands, rocky areas, hedgerows, understorey) were sampled before and after the passage of summer, both in 2017 and 2019. A total of 1724 individuals and 15,516 leaves were collected and measured to estimate the mean values and diversity of SLA of each community. Results:The community-weighted mean and functional divergence have inverse quadratic relationships with the environmental gradient. Shrub communities at both ends of the gradient have low mean SLA values and high functional divergence of this trait. Summer drought implies a generalised decrease in the mean SLA of the communities throughout the gradient, as well as an alteration in functional richness and uniformity. However, the effect of summer drought on the plant community is mediated by the microenvironmental characteristics of its habitat.Conclusions: Drought acclimatisation of shrub communities through phenotypic plasticity leads to rapid changes in their functional leaf structure. In the long term, our results point to an increase in plant conservative strategies, reduced ecosystem productivity, slower nutrient recycling and the reduction of communities of specific habitats as drought increases.

Stress Induces Trait Variability across Multiple Spatial Scales in the Arid Annual Plant Anastatica hierochuntica

“…Unfortunately, we could not support this conclusion by directly testing electrolyte leakage, as we did in the field survey, due to pandemic restrictions. However, this conclusion is supported by other regional-scale studies that found that the costs of plasticity may be higher in unfavorable habitats, particularly for traits such as the SLA that directly impact the plant’s ability to respond to stress factors [ 39 , 40 , 41 ].…”

Linking functional composition moments of the sub-Mediterranean ecotone with environmental drivers

“…This community occupies flat areas with shallow soils (and thus lower water availability) and high soil nutrient contents in Montejo (de la Riva et al, 2023). In these areas, greater aridity would promote the convergence of traits towards conservative strategies (Cornwell and Ackerly, 2009;de la Riva et al, 2018b;Carrascosa et al, 2023). Although shallow soils prevent the accumulation of big amounts of water, the flat terrain favors water accumulation in the soil surface during short periods.…”