Plastic responses to hot temperatures homogenize riparian leaf litter, speed decomposition, and reduce detritivores
Data files
May 31, 2021 version files 68.66 KB
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litter_pack_decomposition_rates.csv
30.31 KB
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litter_pack_invertebrate_communities.csv
15.28 KB
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README.txt
2.79 KB
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source_population_climate_data.csv
1.12 KB
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tree_level_trait_data.csv
19.16 KB
Aug 16, 2023 version files 71.55 KB
Abstract
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 of litter decomposition. Most of the genetic variation in leaf litter traits appeared among rather than within source populations with distinct climate histories. Source populations from hotter climates generally produced litter that decomposed more quickly, but plasticity varied the magnitude of this effect. We also found that hotter growing conditions reduced the variation in litter traits produced across genotypes, homogenizing the litter inputs to riparian ecosystems. All genotypes in the hottest garden produced comparatively small leaves that decomposed quickly and supported lower abundances of aquatic invertebrates, whereas the same genotypes in the coldest garden produced litter with distinct morphologies and decomposition rates. Our results suggest that plastic responses to climate stress may constrict the expression of genetic variation in predictable ways that impact communities and ecosystems. Understanding these interactions between genetic and environmental variation is critical to our ability to plan for the role of foundation species when managing and restoring riparian ecosystems in a warming world.
README: Plastic responses to hot temperatures homogenize riparian leaf litter, speed decomposition, and reduce detritivores
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 populations
we studied (KKH-OPI, JLA-JAK, PSA-SON, CAF-AUG, SCT-MEX, LBW-BIL). The climate variables are from
Wang et al. (2012) and are abbreviated as follows:
Mean annual temperature (MAT)
Temperature difference between warmest and coldest months (TD)
Annual heat-to-moisture index (AHM)
Summer heat-to-moisture index (SHM)
Degree-days above 18oC (DDa18)
Extreme maximum temperature over a 30-year normal (EXT)
Reference atmospheric evaporative demand (Eref)
Wang, T., A. Hamann, D. L. Spittlehouse, and T. Q. Murdock. 2012. ClimateWNA-high-resolution spatial
climate data for western North America. Journal of Applied Meteorology and Climatology 51:16–29.
Dataset 3: Litter Pack Decomposition Rates (.csv)
This file lists decomposition data for each of the 310 litter packs. This includes information about the
litter source (Garden, Population, and Genotype), as well as information about the litter traits and
decomposition rates. The litter traits for each leaf pack (Leaf Area, SLA, C:N) are weighted averages of
the tree-level trait measurements contributing to that pack. Decomposition rate (k) is estimated using
the final ash free dry mass (AFDM) of each pack, which was measured directly, and the initial AFDM,
which was estimated from initial dry mass using a regression derived from handling packs. Also included
is the length of the in-stream decomposition period (Days in Creek) and the random grouping by length
of rebar (Rebar Group).
Dataset 4: Invertebrate Communities (.csv)
This file lists the abundances of each of 13 orders of invertebrates in each of the litter packs assayed for
community composition, along with the information about the litter source (Garden, Population, and
Genotype). Community assays focused on a subset of tree populations from across the climate range
(KKH-OPI, PSA-SON, SCT-MEX, LBW-BIL).