TY - JOUR
T1 - Recycling of nitrogen in herbivore feces
T2 - Plant recovery, herbivore assimilation, soil retention, and leaching losses
AU - Frost, Christopher J.
AU - Hunter, Mark D.
N1 - Funding Information:
Acknowledgements We thank B. Ball, M. Cabrera, R. Canon, D. Coleman, L. Donovan, R. Goergen, C. Hall, S.Helms, P. Hendrix, C. Jennison, J. Malloway, R. Malloy, J. Nelson, K. Wickings, and C. Zehnder for Weld/laboratory assistance and/or comments on previous versions. Comments from Dr Jason Kaye and two anonymous reviewers greatly strengthened the manuscript. John Tanner (Gypsy Moth Rearing Facility, APHIS) supplied space and L. dispar larva. Bob McCron (Canadian Forest Service, Sault Sainte Marie, Ontario) provided tussock moth egg masses. Tom Maddox (Analytical Laboratory, Institute of Ecology) processed all isotope samples. This research is supported by NSF grants DEB-9815133 and DEB-0404876 to M. D. H. and a UGA University-Wide Assistantship to C. J. F. All experiments reported here comply with the current laws of the United States of America.
PY - 2007/2
Y1 - 2007/2
N2 - Herbivores directly and indirectly affect ecosystem functioning in forests. Feces deposition is a direct effect that supplies ephemeral N pulses to soils. Herbivore-mediated changes in plant N allocation and uptake are indirect effects that can also influence soil N availability. These effects may interact if defoliation influences the ability of plants to recover fecal N, and this may affect subsequent generations of herbivores. We added 15N-enriched insect feces (frass) to a series of replicated red oak, Quercus rubra, mesocosms that had been damaged experimentally and then followed the frass N over the course of 2 years. In the first season, some frass N was mineralized in the soil and leached in organic form from the mesocosms within 1 week of deposition. Within 1 month, frass N had been acquired by the oaks and enriched the foliage; late-season herbivores assimilated the frass N within the same growing season. In the second season, herbivore damage from the previous year lowered total leaf N contents and 15N recovered in the foliage. A subsequent cohort of early-season herbivores fed on this foliage consequently derived less of their N from the previous year's frass, and feral leaf rollers colonized fewer of these saplings. The 0- to 5-cm soil fraction was the largest N sink measured, and 42% of the frass N was recovered in the soil. The results demonstrate that: (1) some frass N can be recycled rapidly into foliage and assimilated by successive cohorts of herbivore within the same season; (2) damage can affect N allocation in the following year's foliage, influencing N availability to and host selection by herbivores; and (3) leaching losses occur soon after deposition but are buffered by soil pools, which are the largest sinks for frass N.
AB - Herbivores directly and indirectly affect ecosystem functioning in forests. Feces deposition is a direct effect that supplies ephemeral N pulses to soils. Herbivore-mediated changes in plant N allocation and uptake are indirect effects that can also influence soil N availability. These effects may interact if defoliation influences the ability of plants to recover fecal N, and this may affect subsequent generations of herbivores. We added 15N-enriched insect feces (frass) to a series of replicated red oak, Quercus rubra, mesocosms that had been damaged experimentally and then followed the frass N over the course of 2 years. In the first season, some frass N was mineralized in the soil and leached in organic form from the mesocosms within 1 week of deposition. Within 1 month, frass N had been acquired by the oaks and enriched the foliage; late-season herbivores assimilated the frass N within the same growing season. In the second season, herbivore damage from the previous year lowered total leaf N contents and 15N recovered in the foliage. A subsequent cohort of early-season herbivores fed on this foliage consequently derived less of their N from the previous year's frass, and feral leaf rollers colonized fewer of these saplings. The 0- to 5-cm soil fraction was the largest N sink measured, and 42% of the frass N was recovered in the soil. The results demonstrate that: (1) some frass N can be recycled rapidly into foliage and assimilated by successive cohorts of herbivore within the same season; (2) damage can affect N allocation in the following year's foliage, influencing N availability to and host selection by herbivores; and (3) leaching losses occur soon after deposition but are buffered by soil pools, which are the largest sinks for frass N.
KW - Anisota senatoria
KW - Ecosystem processes
KW - Nitrogen-15
KW - Orgyia leucostigma
KW - Quercus rubra
UR - http://www.scopus.com/inward/record.url?scp=33846595301&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33846595301&partnerID=8YFLogxK
U2 - 10.1007/s00442-006-0579-9
DO - 10.1007/s00442-006-0579-9
M3 - Article
C2 - 17089141
AN - SCOPUS:33846595301
SN - 0029-8549
VL - 151
SP - 42
EP - 53
JO - Oecologia
JF - Oecologia
IS - 1
ER -