Functional Trait Variation Among and Within Species and Plant Functional Types in Mountainous Mediterranean Forests

Abstract

Plant structural and biochemical traits are frequently used to characterise the life history of plants. Although some common patterns of trait covariation have been identified, recent studies suggest these patterns of covariation may differ with growing location and/or plant functional type (PFT). Mediterranean forest tree/shrub species are often divided into three PFTs based on their leaf habit and form, being classified as either needleleaf evergreen (Ne), broadleaf evergreen (Be), or broadleaf deciduous (Bd). Working across 61 mountainous Mediterranean forest sites of contrasting climate and soil type, we sampled and analysed 626 individuals in order to evaluate differences in key foliage trait covariation as modulated by growing conditions both within and between the Ne, Be, and Bd functional types. We found significant differences between PFTs for most traits. When considered across PFTs and by ignoring intraspecific variation, three independent functional dimensions supporting the Leaf-Height-Seed framework were identified. Some traits illustrated a common scaling relationship across and within PFTs, but others scaled differently when considered across PFTs or even within PFTs. For most traits much of the observed variation was attributable to PFT identity and not to growing location, although for some traits there was a strong environmental component and considerable intraspecific and residual variation. Nevertheless, environmental conditions as related to water availability during the dry season and to a smaller extend to soil nutrient status and soil texture, clearly influenced trait values. When compared across species, about half of the trait-environment relationships were species-specific. Our study highlights the importance of the ecological scale within which trait covariation is considered and suggests that at regional to local scales, common trait-by-trait scaling relationships should be treated with caution. PFT definitions by themselves can potentially be an important predictor variable when inferring one trait from another. These findings have important implications for local scale dynamic vegetation models.

Variations in Leaf Traits Modulate Plant Vegetative and Reproductive Phenological Sequencing Across Arid Mediterranean Shrublands

“…In our dataset, the most variable traits were SLA and LPC, whereas the least variable was LCC, which is the most constant nutrient across environments indicating a high abundance of carbon content, in accordance with the results of De la Riva et al ( 2018 ) and Fyllas et al ( 2020 ).…”

“…LNC was higher than that reported by Hernández et al ( 2011 ) and Dominguez et al ( 2012 ) for woody plant species of the Mediterranean ecosystem, proximate to the mesic Mediterranean forest studied by Villar and Merino ( 2001 ), and lower than the xeric Mediterranean forest studied by the same authors, which is explained because our studied species, forming part of dry shrublands, are more adapted to drought which increases the LNC (Inclán et al, 2005 ; Sardans and Peñuelas, 2012 ). The values of LPC were higher than those reported by Dominguez et al ( 2012 ) and Fyllas et al, 2020 ; see Supplementary Material 5: Table S1 ). This is consistent with the fact that a higher LPC improves the water use efficiency in dry studied shrublands, especially in the Sierra Nevada mountain shrublands.…”

“…We explored the variation and relationships at the species, Mediterranean arid shrublands and plant functional group levels, and we hypothesized the following: (1) SLA and leaf nutrients mediate in the vegetative and reproductive phenological plant sequencing through the reduction of vegetative growth phase; (2) species with drought-avoidance mechanisms contribute to an increase in the mean values of the SLA and LNC mainly due to the effect of semideciduous species which, shows similar patterns to deciduous (high SLA and LNC and low PSI); (3) the strong relationships among leaf functional traits and leaf economics spectrum is maintained in arid Mediterranean shrublands through the strong covariation between SLA and leaf nutrients in fast-growing species. Finally, we compared the variation in leaf functional trait values from Mediterranean shrublands with other world and Mediterranean ecosystems previously reported (Villar and Merino, 2001 ; Güsewell, 2004 ; Peter and Oleksyn, 2004 ; Wright et al, 2004 ; Villar et al, 2006 ; Fyllas et al, 2009 , 2020 ; Hernández et al, 2011 ; Dominguez et al, 2012 ; De la Riva et al, 2016 , 2017 ). Overall, this study serves as a relevant plant trait database for functional ecology in the Mediterranean shrublands affected by drought (Tavşanoglu and Pausas, 2018 ).…”

Effective Defense of Aleppo Pine Against the Giant Scale Marchalina hellenica Through Ecophysiological and Metabolic Changes

“…Two fully sunlit branches were collected from the upper crown of each tree using a telescopic scissor. Immediately after cutting, each branch was placed in a water container and was re-cut in water according to the methodology applied for assessing chlorophyll fluorescence ( Pollastrini et al, 2016 ) and gas exchange ( Bahar et al, 2017 ; Fyllas et al, 2017 , 2020 ) of adult trees. While each cut branch was submerged in water, maximum photosynthesis ( A max ) and stomatal conductance ( g s ) were measured on 1-year-old needles using the Li6400XT portable gas exchange analyzer coupled to a Li6400–40 fluorescence chamber (LI-COR, NE, United States).…”

Data_Sheet_1.pdf

“…Two fully sunlit branches were collected from the upper crown of each tree using a telescopic scissor. Immediately after cutting, each branch was placed in a water container and was re-cut in water according to the methodology applied for assessing chlorophyll fluorescence (Pollastrini et al, 2016) and gas exchange (Bahar et al, 2017;Fyllas et al, 2017Fyllas et al, , 2020 of adult trees. While each cut branch was submerged in water, maximum photosynthesis (A max ) and stomatal conductance (g s ) were measured on 1-year-old needles using the Li6400XT portable gas exchange analyzer coupled to a Li6400-40 fluorescence chamber (LI-COR, NE, United States).…”