Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient

Abstract

Phenotypic trait variation plays a major role in the response of plants to global environmental change, particularly in species with low migration capabilities and recruitment success. However, little is known about the variation of functional traits within populations and about differences in this variation on larger spatial scales. In a first approach, we therefore related trait expression to climate and local environmental conditions, studying two temperate forest herbs, Milium effusum and Stachys sylvatica, along a similar to 1800-2500 km latitudinal gradient. Within each of 9-10 regions in six European countries, we collected data from six populations of each species and recorded several variables in each region (temperature, precipitation) and population (light availability, soil parameters). For each plant, we measured height, leaf area, specific leaf area, seed mass and the number of seeds and examined environmental effects on within-population trait variation as well as on trait means. Most importantly, trait variation differed both between and within populations. Species, however, differed in their response. Intrapopulation variation in Milium was consistently positively affected by higher mean temperatures and precipitation as well as by more fertile local soil conditions, suggesting that more productive conditions may select for larger phenotypic variation. In Stachys, particularly light availability positively influenced trait variation, whereas local soil conditions had no consistent effects. Generally, our study emphasises that intra-population variation may differ considerably across larger scales-due to phenotypic plasticity and/or underlying genetic diversity-possibly affecting species response to global environmental change

Variation between individuals fosters regional species coexistence

“…On the other hand, we may expect greater phenotypic plasticity under more favourable conditions because of higher additive genetic variation or larger population sizes (Lemke et al . ).…”

“…moist soil microsites) conferring an advantage to plastic genotypes (Volis et al 1998;Alpert & Simms 2002;Sultan & Spencer 2002). On the other hand, we may expect greater phenotypic plasticity under more favourable conditions because of higher additive genetic variation or larger population sizes (Lemke et al 2015).…”

“…First, greater phenotypic variability in preferred than non-preferred habitats facilitates species coexistence. Recent empirical studies of plant species across marked climate gradients found greater plasticity in favourable sites (Lemke et al 2015). The authors propose that plants benefit from higher morphological variation in favourable environments because resource competition is stronger under these conditions (e.g.…”

Genetic differentiation and plasticity interact along temperature and precipitation gradients to determine plant performance under climate change

“…While Lemke et al . () attempted to separate effects of temperature and precipitation along a wide transect across Europe and suggested a contrary pattern, i.e. higher phenotypic plasticity under warm and wet conditions, their study did not separate phenotypic plasticity from genetic differentiation.…”

Leaf area of meadow plants under regimes of mowing and protection in the Central Forest Reserve

“…Recently, there're a number of databases containing plant functional traits, such as LEDA (Kleyer et al, 2008) or TRY (Kattge et al, 2011), but data from Russia are fragmentary. Also, leaf traits may considerably vary across the habitats, but their variability is poorly studied (Akhmetzhanova et al, 2012;Lemke et al, 2015). That's why it is recommended to measure plant traits directly on the target sites to reveal local patterns of vegetation functional structure (Corlandwehr et al, 2013).…”