Aim Our understanding of the mechanisms that maintain forest diversity under changing climate can benefit from knowledge about traits that are closely linked to fitness. We tested whether the link between traits and seed number and seed size is consistent with two hypotheses, termed the leaf economics spectrum and the plant size syndrome, or whether reproduction represents an independent dimension related to a seed size–seed n...

Lack of tree fecundity data across climatic gradients precludes the analysis of how seed supply contributes to global variation in forest regeneration and biotic interactions responsible for biodiversity. A global synthesis of raw seedproduction data shows a 250‐fold increase in seed abundance from cold‐dry to warm‐wet climates, driven primarily by a 100‐fold increase in seed production for a given tree size. The modest (three...

A major goal of community genetics is to understand the influence of genetic variation within a species on ecological communities. Although well‐documented for some organisms, additional research is necessary to understand the relative and interactive effects of genotype and environment on biodiversity, identify mechanisms through which tree genotype influences communities, and connect this emerging field with existing themes...

Terrestrial systems are thought to be organized predominantly from the bottom‐up, but there is a growing literature documenting top‐down trophic cascades under certain ecological conditions. We conducted an experiment to examine how arthropod community structure on a foundation riparian tree mediates the ability of insectivorous birds to influence tree growth. We built whole‐tree bird exclosures around 35 mature cottonwood ( P...

With the emerging field of community genetics, it is important to quantify the key mechanisms that link genetics and community structure. We studied cottonwoods in common gardens and in natural stands and examined the potential for plant chemistry to be a primary mechanism linking plant genetics and arthropod communities. If plant chemistry drives the relationship between plant genetics and arthropod community structure, then...

We tested the hypothesis that leaf modifying arthropod communities are correlated with cottonwood host plant genetic variation from local to regional scales. Although recent studies found that host plant genetic composition can structure local dependent herbivore communities, the abiotic environment is a stronger factor than the genetic effect at increasingly larger spatial scales. In contrast to these studies we found that de...

We define a genetic similarity rule that predicts how genetic variation in a dominant plant affects the structure of an arthropod community. This rule applies to hybridizing cottonwood species where plant genetic variation determines plant–animal interactions and structures a dependent community of leaf‐modifying arthropods. Because the associated arthropod community is expected to respond to important plant traits, we also te...