Abstract
Evolutionary history and adaptation to climate shape plant traits. Some include leaf traits that influence litter quality. Thus, evolutionary history should affect litter decomposition, a crucial ecosystem process. In addition, litter decomposition is directly influenced by climate. We consequently expect plant phylogeny, adaptation and climate to jointly influence litter decomposition. These effects and their interactions have yet to be untangled at a global scale. Here we present an analysis of variation in litter decomposition rates in rivers and streams across 285 published studies for 239 species (from ferns to angiosperms) distributed at 494 locations world-wide. We estimated the relative contributions of climatic conditions and phylogenetic heritage on litter decomposition rates, partitioning phylogenetic from climatic effects at the site and species levels using phylogenetic eigenvector analysis and phylogenetic linear mixed models. In addition, we modelled transitions in decomposition rates under a suite of multiple adaptive-regime Ornstein–Uhlenbeck models to test the hypothesis that natural selection has shaped clade-level litter decomposition rates. Leaf litter decomposition rate exhibited a significant phylogenetic signal. Modelling decomposition rate as a function of location, climatic niche and phylogeny consistently recovered phylogeny alone as one of the top models in species-level analyses. Since many previous studies have focused on the same species across many locations, we also conducted analyses at the species × site level. Both phylogenetic and climatic factors were favoured in models of this analysis, but the single most important predictor for angiosperms and for all taxa analysed together was phylogeny alone. Synthesis. For plant species distributed globally at nearly 500 locations we found that plant phylogenetic history is a critically important predictor of litter decomposition rate in rivers and streams, explaining more of the variance in decomposition than site or climatic regime. Thus, our study demonstrates the influence of evolutionary history on suites of plant traits that shape a key ecosystem process.
| Original language | English |
|---|---|
| Pages (from-to) | 17-35 |
| Number of pages | 19 |
| Journal | Journal of Ecology |
| Volume | 108 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2020 |
Funding
We thank the LTER Network for funding an initial collaboration in 2011. NAG was supported by the Department of Energy's Office of Science, Biological and Environmental Research. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the US DOE under contract DE-AC05-00OR22725. We thank Chuck Hawkins, Sherri Johnson, Chris Swan, Amy Rosemond and Lydia Zeglin for insightful conversations about this research and for participating in the initial data compilation. We thank Bruce McCune for advice on statistical analyses. We thank Editor Dr. David Wardle and two anonymous reviewers for their comprehensive reviews of this work. All authors have confirmed that they have no relationships, financial or otherwise, that might be perceived as influencing their objectivity or that could be considered a potential source of conflict of interest.
Keywords
- climate
- decomposition rate
- ecosystem process
- evolutionary ecology
- global ecology
- leaf litter
- phylogenetic comparative methods