Land use drives detritivore size structure and decomposition through shifts in resource quality and quantity

Aitor Larrañaga, Daniel M Perkins, Ana Basaguren, Santiago Larrañaga, Jesús Pozo, Jose M Montoya

Research output: Contribution to journalArticlepeer-review


Land use change and nutrient pollution are two pervasive stressors that can modify carbon cycling, as they influence the inputs and the transformation of detritus. Understanding their impact on stream food webs and on diversity is particularly pressing, as streams are largely fuelled by detrital material received from the adjacent riparian environment. Here we assess how a switch from native deciduous forest to Eucalyptus plantations and nutrient enrichment alter the size distribution of stream detritivore communities and decomposition rates of detritus. As expected, more detritus resulted in higher size-independent, or overall, abundance (i.e. higher intercept of size spectra). This change in overall abundance was mainly driven by a change of the relative contribution of large taxa (Amphipoda and Trichoptera), which changed from an average relative abundance of 55.5 to 77.2 % between the sites compared for resource quantity differences in our study. In contrast, detritus quality modified the relative abundance of large vs small individuals (i.e. size spectra slopes), with shallow slopes of size spectra (proportionately more large individuals) associated with sites with nutrient-richer waters and steeper slopes (proportionately fewer large individuals) associated with sites draining Eucalyptus plantations. Decomposition rates of alder leaves due to macroinvertebrates increased from 0.0003 to 0.0142 when relative contribution of large organisms increased (modelled slopes of size spectra: -1.00 and - 0.33, respectively), highlighting the importance of large sized individuals for ecosystem functioning. Our study reveals that land use change and nutrient pollution can greatly impair the transfer of energy through the detrital or 'brown' food web by means of intra- and inter-specific responses to quality and quantity of the detritus. These responses enable linking land use change and nutrient pollution to ecosystem productivity and carbon cycling. [Abstract copyright: Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.]
Original languageEnglish
Pages (from-to)164552
JournalThe Science of the total environment
Early online date4 Jun 2023
Publication statusE-pub ahead of print - 4 Jun 2023


  • Trichoptera
  • Body size
  • Plantation
  • Detritus
  • Amphipod
  • Nutrient enrichment

Cite this