Linkages between detritus-based ("brown") food webs and producer-based ("green") food webs are critical components of ecosystem functionality, but these linkages are difficult to study because soil is opaque and brown food webs are poorly characterized. We used the well-defined detritus-based food web that forms in water-filled leaves of the pitcher plant Sarracenia purpurea to directly study how food web structure affects nitrogen (N) transformation and N-uptake by the plant itself. We used isotopically-enriched prey (detritus) and soluble inorganic N to test three predictions of the hypotheses that N uptake efficiency (UE) by S. purpurea is enhanced by the presence of a complete food web in its pitchers: (1) presence of top trophic levels increases UE of prey-derived, but not inorganic, N; (2) UE is contingent on availability of different forms of N; and (3) congeneric Sarracenia species that do not host food webs differ from S. purpurea in UE of prey-derived N. Surprisingly, none of these predictions were borne out in a 3-month greenhouse experiment. We conclude that the higher trophic-level members of this brown food web actively process detritus, but it is the activity of the microbial component of this web that ultimately influences N-availability in S. purpurea.
This dataset is released to the public and may be freely downloaded. Please keep the designated Contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement. For more information on LTER Network data access and use policies, please see: http://www.lternet.edu/data/netpolicy.html.
Copyright 2017 Environmental Data Initiative.
This material is based upon work supported by the National Science Foundation under grants
#1565103 and #1629233. Any opinions, findings, conclusions, or recommendations
expressed in the material are those of the author(s) and do not necessarily reflect the views of
the National Science Foundation. Please
with questions, comments, or for technical assistance regarding this web site or the
Environmental Data Initiative.
EDI is proud to be affiliated with the following organizations: