@article {KNZ002006, title = {Plant phylogenetic history explains in-stream decomposition at a global scale}, journal = {Journal of Ecology}, volume = {108}, year = {2020}, pages = {17-35}, abstract = {

\ \ \  1. 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.
\ \ \  2. 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.
\ \ \  3. 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.
\ \ \  4. 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.

}, keywords = {LTER-KNZ}, issn = {0022-0477}, doi = {10.1111/1365-2745.13262}, url = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.13262}, author = {LeRoy, Carri J. and Hipp, Andrew L. and Lueders, Kate and Follstad Shah, Jennifer J. and Kominoski, John S. and Ard{\'o}n, Marcelo and W. K. Dodds and Gessner, Mark O. and Griffiths, Natalie A. and Lecerf, Antoine and Manning, David W. P. and Sinsabaugh, Robert L. and Webster, Jack R.}, editor = {Wardle, David} } @article {KNZ001918, title = {Continental-scale decrease in net primary productivity in streams due to climate warming}, journal = {Nature Geoscience}, volume = {11}, year = {2018}, pages = {415 - 420}, abstract = {

Streams play a key role in the global carbon cycle. The balance between carbon intake through photosynthesis and carbon release via respiration influences carbon emissions from streams and depends on temperature. However, the lack of a comprehensive analysis of the temperature sensitivity of the metabolic balance in inland waters across latitudes and local climate conditions hinders an accurate projection of carbon emissions in a warmer future. Here, we use a model of diel dissolved oxygen dynamics, combined with high-frequency measurements of dissolved oxygen, light and temperature, to estimate the temperature sensitivities of gross primary production and ecosystem respiration in streams across six biomes, from the tropics to the arctic tundra. We find that the change in metabolic balance, that is, the ratio of gross primary production to ecosystem respiration, is a function of stream temperature and current metabolic balance. Applying this relationship to the global compilation of stream metabolism data, we find that a 1\ \°C increase in stream temperature leads to a convergence of metabolic balance and to a 23.6\% overall decline in net ecosystem productivity across the streams studied. We suggest that if the relationship holds for similarly sized streams around the globe, the warming-induced shifts in metabolic balance will result in an increase of 0.0194\ Pg carbon emitted from such streams every year.

}, keywords = {LTER-KNZ}, doi = {10.1038/s41561-018-0125-5}, url = {http://www.nature.com/articles/s41561-018-0125-5}, author = {Song, Chao and W. K. Dodds and R{\"u}egg, Janine and Argerich, Alba and Baker, Christina L. and W.B. Bowden and Douglas, Michael M. and Farrell, Kaitlin J. and Flinn, Michael B. and Garcia, Erica A. and Helton, Ashley M. and Harms, Tamara K. and Jia, Shufang and Jones, Jeremy B. and Koenig, Lauren E. and Kominoski, John S. and McDowell, William H. and McMaster, Damien and Parker, Samuel P. and Rosemond, Amy D. and Ruffing, Claire M. and Sheehan, Ken R. and Trentman, Matt T. and M.R. Whiles and Wollheim, Wilfred M. and Ballantyne, Ford} } @article {KNZ001810, title = {Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers}, journal = {Global Change Biology}, volume = {23}, year = {2017}, pages = {3064-3075}, abstract = {

Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. Here, we synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by the activation energy (Ea, in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which Ea could be calculated. Higher values of Ea were correlated with lower-quality litter, but these correlations were influenced by a single, N-fixing genus (Alnus). Ea values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the Ea was 0.34 \± 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5\–21\% with a 1\–4 \°C rise in water temperature, rather than a 10\–45\% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in Ea values for these regions (0.75 \± 0.13 eV and 0.27 \± 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that Ea values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global scale.

}, keywords = {LTER-KNZ}, doi = {10.1111/gcb.13609}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13609}, author = {Follstad-Shah, J.J. and Kominoski, John S. and Ard{\'o}n, Marcelo and W. K. Dodds and Gessner, Mark O. and Griffiths, Natalie A. and Hawkins, Charles P. and Johnson, Sherri L. and Lecerf, Antoine and LeRoy, Carri J. and Manning, David W. P. and Rosemond, Amy D. and Sinsabaugh, Robert L. and Swan, Christopher M. and Webster, Jackson R. and Lydia H. Zeglin} } @article {KNZ001708, title = {Baseflow physical characteristics differ at multiple spatial scales in stream networks across diverse biomes}, journal = {Landscape Ecology}, volume = {31}, year = {2016}, pages = {119-136}, abstract = {

Context Spatial scaling of ecological processes is facilitated by quantifying underlying habitat attributes. Physical and ecological patterns are often measured at disparate spatial scales limiting our ability to quantify ecological processes at broader spatial scales using physical attributes. Objective We characterized variation of physical stream attributes during periods of high biological activity (i.e., baseflow) to match physical and ecological measurements and to identify the spatial scales exhibiting and predicting heterogeneity. Methods We measured canopy cover, wetted width, water depth, and sediment size along transects of 1st\–5th order reaches in five stream networks located in biomes from tropical forest to arctic tundra. We used hierarchical analysis of variance with three nested scales (watersheds, stream orders, reaches) to identify scales exhibiting significant heterogeneity in attributes and regression analyses to characterize gradients within and across stream networks. Results Heterogeneity was evident at one or multiple spatial scales: canopy cover and water depth varied significantly at all three spatial scales while wetted width varied at two scales (stream order and reach) and sediment size remained largely unexplained. Similarly, prediction by drainage area depended on the attribute considered: depending on the watershed, increases in wetted width and water depth with drainage area were best fit with a linear, logarithmic, or power function. Variation in sediment size was independent of drainage area. Conclusions The scaling of ecologically relevant baseflow physical characteristics will require study beyond the traditional bankfull geomorphology since predictions of baseflow physical attributes by drainage area were not always best explained by geomorphic power laws.

}, keywords = {LTER-KNZ, Boreal forest, Geomorphology, Grasslands, Nested ANOVA, Scaling, Temperate forest}, issn = {0921-2973}, doi = {10.1007/s10980-015-0289-y}, url = {https://link.springer.com/article/10.1007\%2Fs10980-015-0289-y}, author = {R{\"u}egg, Janine and W. K. Dodds and Daniels, M.D. and Sheehan, Ken R. and Baker, Christina L. and W.B. Bowden and Farrell, Kaitlin J. and Flinn, Michael B. and Harms, Tamara K. and Jones, J.B. and Koenig, Lauren E. and Kominoski, John S. and W.H. McDowell and Parker, Samuel P. and Rosemond, Amy D. and Trentman, Matt T. and M.R. Whiles and Wollheim, Wilfred M.} }