Plastic responses to hot temperatures homogenize riparian leaf litter, speed decomposition, and reduce detritivores

Efforts to maintain the function of critical ecosystems under climate change often begin with foundation species. In the southwestern US, cottonwood trees support diverse communities in riparian ecosystems that are threatened by rising temperatures. Genetic variation within cottonwoods shapes communities and ecosystems, but these effects may be modified by phenotypic plasticity, where genotype traits change in response to environmental conditions. Here, we investigated plasticity in Fremont cottonwood (Populus fremontii) leaf litter traits as well as the consequences of plasticity for riparian ecosystems. We used three common gardens each planted with genotypes from six genetically divergent populations spanning a 12oC temperature gradient, and a decomposition experiment in a common stream environment. We found that leaf litter area, specific leaf area, and carbon to nitrogen ratio (C:N) were determined by interactions between genetics and growing environment, as was the subsequent rate..., , , # Plastic responses to hot temperatures homogenize riparian leaf litter, speed decomposition, and reduce detritivores

[https://doi.org/10.5061/dryad.31zcrjdkh](https://doi.org/10.5061/dryad.31zcrjdkh)

## Description of the data and file structure

**Dataset 1: Tree Level Trait Data (.csv)**

This file lists information about each tree (Garden, Population, Genotype) and the trait values (Leaf

Area, SLA, C:N) for that tree. It also includes the total weight of litter from that tree that was included in

the litter packs for that genotype from that garden. This was used to calculate weighted averages for

each trait in each litter pack.

**Dataset 2: Source Population Climate Data (.csv)**

This file lists GPS coordinates, elevation, and climate variables for all 16 populations grown in the

common gardens. These data were used to construct the climate PCA, which was then used to test for

relationships between home climate and the magnitude of phenotypic plasticity in the six pop...