DOI: 10.5061/dryad.c866t1ghg
title: A global synthesis on land-cover changes in watersheds shaping freshwater detrital food webs

description: Anthropogenic land-cover changes are among the most pressing global
 threats to both aquatic and terrestrial ecosystems, jeopardising
 biodiversity and the critical connections between these systems. Resource
 flows and trophic interactions intricately link aquatic and terrestrial
 ecosystems, with terrestrial-derived detritus playing a foundational role
 in supporting aquatic food webs. These detrital inputs form essential
 cross-ecosystem linkages, underpinning key ecological processes and
 providing vital resources for aquatic communities. Yet, little research
 has focused on how land-cover changes cascade across this linkage. To
 better understand how land-cover changes in the watershed influence
 freshwater detrital food webs, we conducted a meta-analysis of field
 studies reporting the effects of vegetation changes on freshwater detrital
 consumers and organic matter decomposition. The results from 144 studies,
 reporting 1235 comparisons, showed that, overall, land-cover changes in
 the watershed vegetation, especially through harvest and land-use
 conversion, have negative effects on aquatic biodiversity and ecosystem
 processes. These vegetation changes reduced diversity, abundance, and
 biomass across multiple trophic levels in freshwater detrital food webs.
 Studies examining multiple organism groups most often observed negative
 responses across multiple trophic levels, suggesting that the land-cover
 changes negatively affected multiple detrital food web components
 simultaneously. Our results also show that outcomes of restoration of
 watershed vegetation were context-dependent, and no clear trend of
 improvement was visible. Therefore, conservation of natural riparian and
 catchment vegetation are key to maintain freshwater ecosystem processes
 and aquatic biodiversity worldwide, and more efficient and evidence-based
 restoration measures are urgently needed. As our global synthesis shows
 that direct human-induced alterations of vegetation type in watersheds
 have significant negative effects on freshwater detrital food webs, there
 is a pressing need to consider cross-ecosystem consequences of land-cover
 changes in conservation and ecosystem management.
description: # A global synthesis on land-cover changes in watersheds shaping
 freshwater detrital food webs This READ ME file contains information on
 the R-scripts and variables in the datasets used for the analyses. ###
 Data files: dat_MA.txt: Main dataset with information on each observation
 of each study, with the following variables: * study_ID - Levels: several;
 unique identifier for each study (detailed infos can be found in the
 Supplementary material Table S5 and data sources) * ID - Levels:
 continuous: unique identifier for each comparison * year - Levels:
 continuous, publication year * lat - Levels: continuous; latitude in
 decimal degrees * lon - Levels: continuous; longitude in decimal degrees *
 climate - Levels: boreal, temperate; sub-tropical, tropical, climate zone
 * season - Levels: year, winter, spring, summer, autumn, dry, wet;
 timepoint of field study * scale - Levels: local, catchment,
 local+catchment; spatial scale of field study * temp_diff - Levels:
 continuous; temporal difference between before and after comparison in
 days * space_diff - Levels: continuous; spatial difference between
 reference and altered comparison in meters * duration - Levels:
 continuous; duration of decomposition assays in days * water_body -
 Levels: several; type of water body, e.g., stream * strahler - Levels:
 continuous; Strahler order * veg_change - Levels: several; type of
 vegetation change according to authors * width_ref - Levels: continuous; m
 width of riparian vegetation in the reference condition * width_alt -
 Levels: continuous; m width of riparian vegetation in the altered
 condition * cover_ref - Levels: continuous; % cover of refernence
 vegetation of riparian vegetation in the reference condition * cover_alt -
 Levels: continuous; % cover of reference vegetation of the reference
 condition * veg_ref - Levels: several; characterisation of reference
 vegetation and land cover * veg_alt - Levels: several; characterisation of
 altered vegetation and land cover * fw_category - Levels: 1-6; 1=
 detritus, 2= microbes, 3= macroinvertebrates+fish, 4= microbial
 decomposition, 5= shredder-mediated decomposition, 6= total decomposition
 * fct_group - Levels: 1-3, functional group with 1= detritus, 2= microbes,
 3= macroinvertebrates+fish * om_type - Levels: several, organic matter
 type, e.g., leaf * om_taxon - Levels: several, taxon name for organic
 matter * microbe_type - Levels: several, type of microbe, e.g., bacteria *
 invert_type - Levels: several, type of invertebrate, e.g.,
 macroinvertebrate * compartment_type - Levels: CPOM, benthic, water
 column, where organisms were collected * metric - Levels: abundance,
 diversity, biomass, decomposition as ecosystem and community metrics *
 unit - Levels: several; unit in which metric was reported * mean_ref -
 Levels: continuous; mean reference value of this comparison * mean_alt -
 Levels: continuous; mean altered value of this comparison * n_ref -
 Levels: continuous; number of replications in the reference condition of
 this comparison * n_alt - Levels: continuous; number of replications in
 the altered condition of this comparison * origin - Levels: several; data
 origin description * dataorigin - Levels: reported = either text, table or
 provided by authors, estimated= from figure extracted * trophy - Levels:
 1-4; 1= detritus, 2= microbes, 3= shredders, 4= omnivores *
 Imputed_Value_ref - Levels: continuous; if imputed, new value for
 reference condition * Imputed_Value_alt - Levels: continuous; if imputed,
 new value for altered condition * sd_ref3 - Levels: continuous; standard
 deviation of reference value of this comparison * sd_alt3 - Levels:
 continuous; standard deviation of altered value of this comparison
 R-scripts: Run in R (version 4.4.1) on Windows. Data_Distribution:
 requires dat_MA. Descriptive Analysis of the Dataset. Outputs are
 Manuscript Figures 2 and Figures S8-S10. Data_Analyis_ES: requires dat_MA.
 Main Analysis of Effect Size for each moderator. Otuputs are Tables 1-2,
 Figures 3-4, and Table S2. Data_Analyis_Multitropy: requires dat_MA. Main
 Analysis of Effect Size for multitrophic effects. Otuputs are Figure 5.
 Data_Analyis_PublicationBias: requires dat_MA. Analysis for assessing
 publication bias. Otuputs are Figures S1-S5 and Table S5.
 Data_Analyis_Sensitiviy: requires dat_MA. Sensitivity analysis. Otuputs
 are Figures S6-S7 and Tables S3-S4.