Genetic richness affects trait variation but not community productivity in a tree diversity experiment

Abstract

Biodiversity-ecosystem functioning experiments found that productivity generally increases with species richness, but less is known about effects of within-species genetic richness and potential interactions between the two. While functional differences between species can explain species richness effects, empirical evidence regarding functional differences between genotypes within species and potential consequences for productivity is largely lacking. We therefore measured within-and among-species variation in functional traits and growth and determined stand-level tree biomass in a large forest experiment factorially manipulating species and genetic richness in subtropical China. Within-species variation across genetic seed families, in addition to variation across species, explained a substantial amount of trait variation. Furthermore, trait responses to species and genetic richness varied significantly within and between species. Multivariate trait variation was larger among individuals from species mixtures than those from species monocultures, but similar among individuals from genetically diverse vs genetically uniform monocultures. Correspondingly, species but not genetic richness had a positive effect on stand-level tree biomass. We argue that identifying functional diversity within and among species in forest communities is necessary to separate effects of species and genetic diversity on tree growth and community productivity.

Remotely sensed between‐individual functional trait variation in a temperate forest

“…In our case, the two architectural traits PAI and CH showed very strong plasticity (more than 30% of total variation), increasing with PAR, whereas the three biochemical traits showed weaker responses (around 10% of total variation) that also varied more among species. Spatial and residuals variation among individuals within species was large for all traits, which is typical for analysis of field‐measured individual trait data (Bongers et al., 2020 ; Li et al., 2017 ). Together spatial and residual variation could reflect biotic or abiotic microenvironmental variation (Pearson & Dawson, 2003 ), genetic variation, or different tree developmental stages such as different tree age (Funk et al., 2017 ).…”

“…In our case, the two architectural traits PAI and CH showed very strong plasticity (more than 30% of total variation), increasing with PAR, whereas the three biochemical traits showed weaker responses (around 10% of total variation) that also varied more among species. Spatial and residuals variation among individuals within species was large for all traits, which is typical for analysis of fieldmeasured individual trait data (Bongers et al, 2020;Li et al, 2017).…”

“…Substantial trait variation among individuals within species could be related to environmental gradients across the site, to which the species responded in parallel (main effects of environmental variables in tables from Appendices 8 , 9 , 10 , 11 , 12 , 13 , 14 ) and also with some significant variation (interactions in tables from Appendices 8 , 9 , 10 , 11 , 12 , 13 , 14 ). Such plasticity (Bradshaw, 1965 ; Sultan, 2000 ) allows a single species to perform well over a range of environmental conditions, thus affecting both its own performance as potentially also the performance of the entire plant community (Bongers et al., 2020 ; Roscher et al., 2018 ). Typically, traits that are particularly important for plant growth express adaptive plasticity, whereas other traits may be more constantly expressed across different environments, for example, plant reproductive traits (Schmid, 1992 ).…”

“…Within‐species trait variation can be large between sites due to large‐scale abiotic and biotic gradients (He et al., 2009 ) as well as within sites due to environmental heterogeneity and interactions between individuals (Auger & Shipley, 2013 ; Li et al., 2017 ; Roscher et al., 2018 ; Siefert et al., 2015 ) and due to genetic variation within species. Within‐species trait variation can affect community assembly and ecosystem functioning (Violle et al., 2012 ); however, to which extent it does so remains poorly investigated (Bongers et al., 2020 ). Here, we assess the within‐ and between‐species trait variation using remote sensing (RS).…”

Charting a course for genetic diversity in the UN Decade of Ocean Science

“…However, the evolutionary and ecological effects of genetic diversity are not always clear‐cut. Variation in the effects of genetic diversity on ecosystem function and community composition have been observed between species, on different aspects of community assemblage, under various levels of stress, and over different spatial and community scales (Barantal et al, 2019; Bongers et al, 2020; Chalmandrier et al, 2017; DuBois et al, 2021; Raffard et al, 2019). Furthermore, epigenetic influences from variation in the present‐ and past‐generation environments have also been found to add to functional diversity within species, complicating the estimation of contributions from genetic diversity to ecological function and adaptation (Bogan et al, 2020; Nguyen et al, 2020; Puy et al, 2020).…”