Tree genetics strongly affect forest productivity, but intraspecific diversity–productivity relationships do not

Abstract

Summary Numerous studies have demonstrated biodiversity–productivity relationships in plant communities, and analogous genetic diversity–productivity studies using genotype mixtures of single species may show similar patterns. Alternatively, competing individuals among genotypes within a species are less likely to exhibit resource‐use complementarity, even when they exhibit large differences in their effects on ecosystem function. In this study, we test the impact of genotype diversity and genetic identity on ecosystem function using an ecosystem‐scale common garden experiment. Distinct tree genotypes were collected across the entire natural range of the riparian tree Populus fremontii in the USA, and grown in 1–16 genotype combination forest stands. Due to the warm climate and irrigation of the planting location along the Colorado River (AZ, USA), mature forest physiognomy with trees up to 19 m tall was achieved in just five years. Several key patterns emerged: (i) genotype richness did not predict forest productivity, suggesting a lack of net biodiversity effects; (ii) we found differences among genotype monoculture stands comparable to differences in average productivity across all forest biomes on Earth; (iii) productivity was predicted based on genetic marker similarity in trees; (iv) genetic‐based differences in leaf phenology (early leaf‐on and late leaf‐fall timing) were correlated with >80% of the variation in tree and forest productivity irrespective of home‐site conditions. Large differences in productivity among genotypes can result in dramatic differences in forest productivity without resulting in diversity–productivity relationships that are present in species‐scale biodiversity studies.

Genotypic variation in phenological plasticity: Reciprocal common gardens reveal adaptive responses to warmer springs but not to fall frost

“…(a) There will be variation in phenological plasticity. Given previous evidence of genetic variation in functional traits in this species (Fischer et al, 2017;Grady et al, 2013;Grady, Kolb, Ikeda, & Whitham, 2015), coupled with the steep environmental gradient across the three gardens, we hypothesized that there will be significant genetic (G), environmental (E), and GxE effects on bud set and bud flush. (b) Phenotypic plasticity of individual genotypes will be related to their place of origin.…”

Multiple dimensions of intraspecific diversity affect biomass of eelgrass and its associated community

“…, Fischer et al. ). However, we show that different metrics of intraspecific diversity capture fundamentally different components of biodiversity and should be treated as complementary rather than competing dimensions of biodiversity that influence assemblage performance.…”

“…Considerable current research examines the utility of different diversity measures for describing the speciesdiversity-ecosystem-functioning relationship (Cadotte et al 2008, Flynn et al 2011, Fischer et al 2017). However, we show that different metrics of intraspecific diversity capture fundamentally different components of biodiversity and should be treated as complementary rather than competing dimensions of biodiversity that Notes: Block was included as a random effect in all models; but block effect results are omitted for brevity.…”

“…Analogously, genetic relatedness or allelic diversity within species could be more closely linked to trait diversity and assemblage performance than genotype richness (Massa et al 2013, Fischer et al 2017. However there is considerable uncertainty in this relationship.…”

Genetic and Spatial Structuring of Populus tremuloides in a Mixed-Species Forest of Southwestern Utah, USA

“…Maintaining genetic diversity is an important objective for many land managers as it can contribute to increased resilience of aspen to future climate variability and increasing drought. Characterization of genetic diversity at the landscape scale could be an important metric for decision-making in forest management (Fischer et al 2017 and references therein), but may be cost prohibitive at present using traditional genetic approaches. We concur with Madritch et al (2014) that remotely sensed data with high tem poral resolution may be a useful and economical tool for delineating extent and pattern of genetic diversity in forests.…”