Linking tree genetics and stream consumers: isotopic tracers elucidate controls on carbon and nitrogen assimilation

Zacchaeus G. Compson, Bruce A. Hungate, Thomas G. Whitham, George W. Koch, Paul Dijkstra, Adam C. Siders, Todd Wojtowicz, Ryan Jacobs, David N. Rakestraw, Kiel E. Allred, Chelsea K. Sayer, Jane C. Marks

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Leaf litter provides an important nutrient subsidy to headwater streams, but little is known about how tree genetics influence energy pathways from litter to higher trophic levels. Despite the charge to quantify carbon (C) and nitrogen (N) pathways from decomposing litter, the relationship between litter decomposition and aquatic consumers remains unresolved. We measured litter preference (attachments to litter), C and N assimilation rates, and growth rates of a shredding caddisfly (Hesperophylax magnus, Limnephilidae) in response to leaf litter of different chemical and physical phenotypes using Populus cross types (P. fremontii, P. angustifolia, and F1 hybrids) and genotypes within P. angustifolia. We combined laboratory mesocosm studies using litter from a common garden with a field study using doubly labeled litter (13C and 15N) grown in a greenhouse and incubated in Oak Creek, Arizona, USA. We found that, in the lab, shredders initially chose relatively labile (low lignin and condensed tannin concentrations, rapidly decomposing) cross type litter, but preference changed within 4 d to relatively recalcitrant (high lignin and condensed tannin concentrations, slowly decomposing) litter types. Additionally, in the lab, shredder growth rates were higher on relatively recalcitrant compared to labile cross type litter. Over the course of a three-week field experiment, shredders also assimilated more C and N from relatively recalcitrant compared to labile cross type litter. Finally, among P. angustifolia genotypes, N assimilation by shredders was positively related to litter lignin and C:N, but negatively related to condensed tannins and decomposition rate. C assimilation was likewise positively related to litter C:N, and also to litter %N. C assimilation was not associated with condensed tannins or lignin. Collectively, these findings suggest that relatively recalcitrant litter of Populus cross types provides more nutritional benefit, in terms of N fluxes and growth, than labile litter, but among P. angustifolia genotypes the specific trait of litter recalcitrance (lignin or tannins) determines effects on C or N assimilation. As shredders provide nutrients and energy to higher trophic levels, the influence of these genetically based plant decomposition pathways on shredder preference and performance may affect community and food web structure.

Original languageEnglish (US)
Pages (from-to)1759-1770
Number of pages12
Issue number8
StatePublished - Aug 2018


  • Populus
  • aquatic consumers
  • assimilation
  • carbon
  • condensed tannins
  • intraspecific variation
  • isotopic tracer
  • leaf litter
  • lignin
  • litter decomposition
  • nitrogen
  • tree genetics

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


Dive into the research topics of 'Linking tree genetics and stream consumers: isotopic tracers elucidate controls on carbon and nitrogen assimilation'. Together they form a unique fingerprint.

Cite this