DOI: 10.5061/dryad.r7sqv9smr
title: Riparian forests and macroinvertebrates support multiple ecosystem processes across temperate and tropical streams

description: Ecosystems are interconnected, and ecological processes frequently
 transcend the physical boundaries that define them. Fluxes of energy,
 matter, and organisms not only form important ecosystem processes within
 but also between ecosystems. However, the role of biological drivers in
 simultaneously supporting multiple ecosystem processes at the interface
 between aquatic and terrestrial ecosystems (i.e., aquatic-terrestrial
 ecosystem processes) remains poorly understood, both locally and across
 regions. To assess the relative importance of riparian forests, detritus
 consumers, and leaf litter mixing on different ecosystem processes of
 freshwater detrital food webs, we used leaf litter bags to subsidise local
 terrestrial leaf litter to forested and non-forested headwater stream
 sites in a temperate and tropical region. We also manipulated
 macroinvertebrate access and the composition of leaf litter mixtures. We
 measured three key aquatic-terrestrial ecosystem processes: biomass
 accrual of aquatic fungi, nitrogen loss, and decomposition rates of local
 leaf litter. Across both temperate and tropical streams, ecosystem
 multifunctionality, i.e., the simultaneous sustaining of these processes,
 was positively associated with macroinvertebrates and riparian forests but
 not with leaf litter mixing. Especially, leaf litter nitrogen loss and
 decomposition rates were consistently higher when macroinvertebrates had
 access across all leaf litter species. Decomposition rates were also
 positively associated with other ecosystem processes. These findings
 highlight consistent, cross-regional effects of riparian forests and
 macroinvertebrate detritivores on freshwater detrital food webs. In a
 rapidly changing world, understanding ecosystem processes in headwater
 streams demands a holistic view that transcends ecosystem borders and
 incorporates cross-ecosystem interactions.
description: # Riparian forests and macroinvertebrates support multiple ecosystem
 processes across temperate and tropical streams Dryad
 DOI: https://doi.org/10.5061/dryad.r7sqv9smr Rebecca Oester, Paula M. de
 Omena, Larissa Corteletti, Marcelo S. Moretti, Florian Altermatt, Andreas
 Bruder [rebecca.oester@eawag.ch](mailto:rebecca.oester@eawag.ch) This READ
 ME file contains information on the R scripts and variables in the
 datasets used for the analyses. Datafiles: 1. dat.ergx Main dataset with
 information on each leaf litter bag with the following variables:
 Sample_ID: Unique identifier for each treatment (leaf litter in each bag);
 NA for Brazil because of naming differences Site: Site identifier (Ending
 F indicating forested and ending A indicating non-forested) Country: Study
 country (either Switzerland or Brazil) Region: Region identifier for
 Switzerland and Brazil Stream: Stream identifier Vegetation: Riparian
 vegetation type (either forested or non-forested) Mesh: Mesh size of leaf
 litter bag (either fine or coarse mesh) LeafLeafLeaf: Leaf species (either
 Alder, Ash, Inga, or Miconia) MonoMix: Indication of whether the species
 was in a single-species leaf litter bag (mono) or mixed (mix) LeafLeaf:
 String combination of leaf species and mix EA_N_Percent_corr: % Nitrogen
 in the leaf litter at the end of the experiment measured with an elemental
 analyzer EA_C_Percent_corr: % Carbon in the leaf litter at the end of the
 experiment measured with an elemental analyzer molar_CN: molar ratio
 between Nitrogen and Carbon log_molar_CN: logged value of molar_CN N_Loss:
 % Nitrogen lost based on calculations in Handa et al (2014) C_Loss: %
 Carbon lost based on calculations in Handa et al (2014)
 Fungal_Biom_Leaf_mgg_noRR_1: Fungal Biomass in mg / g leaf as proxy for
 fungal secondary production k_corr1: the decay rate k based on the decay
 function incorporating initial and final mass and time progress expressed
 as Temperature degree days (dd ^-1^). Delta15_N_Air: the stable isotope
 signature of N (‰) Delta13_C_VPDB: the stable isotope signature of C (‰)
 Delta_logCN_abs: the difference in C:N ratio from initial and final leaves
 ID: string combination of sample ID and leafleaf Group: treatment
 combination (string combination of MonoMix, Vegetation, and Mesh) 1. SEM
 Dataset used to visualize and summarize effect sizes from the SEM (summary
 outputs from SEM.r) model: Description of individual links of the SEM
 variables (Intercepts, NLoss ~ Mesh, etc.) Estimate: Effect size of the
 links Est.Error: estimated error l95: lower 95% interval u05: upper 95%
 interval Rhat: R hat (indication of fit) Bulk_ESS: Computes a bulk
 effective sample size estimate for a single variable. Bulk_ESS is useful
 as a diagnostic for the sampling efficiency. Tail_ESS: Computes a tail
 effective sample size estimate for a single variable. Tail_ESS is useful
 as a diagnostic for the sampling efficiency in the tails of the posterior.
 It is defined as the minimum of the effective sample sizes for the 5% and
 95% quantiles. species: Leaf litter species (Alder, Ash, Inga, Miconia)
 modelabc: Letters A-L indicating corresponding links in Figure 4 type:
 description of link type R-scripts: Run in R (version 4.1.2) on Linux. 1.
 Multifunctionality requires dat.ergx.csv With getStdAndMeanFunctions(),
 the three functions (decomposition rate (k), N loss, and fungal secondary
 production) get scaled and averaged to calculate an overall
 multifunctionality score. This score and the individual functions get
 analyzed and plotted depending on the leaf litter species and treatment
 effect separately using the brms() function. 1. SEM requires dat.ergx.csv
 After data preparation, for each leaf litter separately, a big SEM with
 links specified in the manuscript is run and analyzed. 1. Slopes requires
 SEM.csv From the SEM analyses, the summary outputs are aggregated and
 visualized to produce Figure 4 in the manuscript.