DOI: 10.5061/dryad.8pk0p2nv9
title: Riparian forests shape trophic interactions in detrital stream food webs

description: Freshwater and terrestrial biodiversity are linked through spatial
 resource flows. Key examples are detrital subsidies from the riparian
 vegetation that form the base of food webs in small streams. Despite the
 central role of detritivores in these food webs, the consequences of
 altered riparian vegetation type and resource availability on their
 trophic strategies are less known. Therefore, we experimentally
 tested the direct and indirect effects of riparian vegetation type (i.e.,
 riparian forests present vs. absent) on trophic interactions and dietary
 imbalances of aquatic detritivores. To characterize trophic strategies, we
 used stoichiometric and isotopic differences between consumers and
 resources as functional measures of trophic link strength in leaf litter
 bags naturally colonised by stream decomposers and detritivores. Our
 results show that an absence of riparian forests affected stoichiometric
 and isotopic properties in stream detrital food webs. Where local riparian
 forests were absent, leaf litter showed lower C:N ratios, which only
 trichopteran detritivores mirrored, whereas plecopteran and crustacean
 detritivores showed differences in their isotopic signatures. Diverging
 patterns between resources and consumers could lead to a rewiring of
 energy flow paths and weaken the coupling between aquatic detritivores and
 terrestrial detritus. Consequently, our findings demonstrate that
 riparian forests are essential for aquatic food webs by not only
 influencing organisms themselves but also their trophic interactions and
 energy flow paths. Aquatic detritivores depending on terrestrial subsidies
 can be highly sensitive to local changes in their resource environment.
 Therefore, functionally divergent patterns between resources and consumers
 in recipient systems highlight how habitat properties of the donor system
 can affect food webs connected across ecosystem boundaries.
description: # Riparian forests shape trophic interactions in detrital stream food webs
 [https://doi.org/10.5061/dryad.8pk0p2nv9](https://doi.org/10.5061/dryad.8pk0p2nv9) ## Description of the data and file structure The three datasets used for this study include identifiers, treatments, measurements of stoichiometry, and stable isotopes of leaf litter and macroinvertebrate consumers, as well as fungal biomass, and also some information on the local macroinvertebrate community composition. dat.erg: Data on resources including fungal biomass, stoichiometry, and stable isotopes dat.all: Data on resources and consumers (shredders), stoichiometry, and stable isotopes dat.tot: Taxalist of all animals found in the experimental units Identifiers: * "Sample_ID": shared identifier * "Site": study site identifier (combination between stream and vegetation) * "Stream": stream site identifier (within each region, four streams) * "Region": regional site identifier (two regions corresponding to the two Swiss cantons) Treatments: * "LeafLeafLeaf": leaf species * "Vegetation": forested or non-forested riparian vegetation * "MonoMix": one or two species of leaf litter in the experimental bags * "Shredder": if the specimen is a shredder: "Y"; otherwise "N" * "T": timepoint either "T0" (before stream incubation) or "sample" (after stream incubation) * "Species_All_1": Taxon used Values: * "Delta13_C_VPDB_corr": d13C stable isotope values * "Delta13_C_VPDB_corr_corr": d13C isotope values with correction factor * "Delta15_C_Air_corr": d15N stable isotope values * "log_molar_CN": C:N ratio as logged molar ratio values * "EA_C_Percent_corr": %C values * "EA_N_Percent_corr": %N values * "Fungal_Biom_Leaf_mgg_noRR": fungal biomass per leaf in mg/g Macroinvertebrate community: * "Order": order-level identification * "Family": family-level identification * "Genus": genus-level identification (or sp.) * "Species": species-level identification * "Taxon": the lowest taxonomic level determined * "Total": number of individuals per leaf litter bag * "DryMass": average dry weight of this taxon in this leaf litter bag based on taxon-specific length-weight regressions in mg * "TotalDryMass": the total dry mass of all these taxa in this leaf litter bag in mg ## Sharing/Access information Sample_ID in all three files is the common identifier linking the three data frames. Please note that opening the data.all.txt file in Excel shifts the data so the last column does not have the correct header. CSV files with the correct format are included. Note that these are semicolon-delimited. ## Code/Software We performed all calculations and statistical analyses in R (version 4.1.2; R Development Core Team, 2020). All code that was used to analyze this data can be found on GitHub (link in Related Works section).