TY - JOUR
T1 - Stream carbon and nitrogen supplements during leaf litter decomposition
T2 - contrasting patterns for two foundation species
AU - Pastor, Ada
AU - Compson, Zacchaeus G.
AU - Dijkstra, Paul
AU - Riera, Joan L.
AU - Martí, Eugènia
AU - Sabater, Francesc
AU - Hungate, Bruce A.
AU - Marks, Jane C.
N1 - Funding Information:
Acknowledgments We thank the Marks, Sabater and Martí labs for their support and feedback on this study. Dr Susana Bernal, Dr Bob Hall and two anonymous reviewers provided helpful comments on an early draft of this manuscript. The Coconino Forest Service provided us with access to sites near Oak Creek. The National Science Foundation provided funding through the Frontiers in Integrative Biological Research (DEB-0425908), Integrative Graduate Education and Research Traineeship (DGE-0549505), and Ecosystem Studies (DEB-1120343) research programs. Funding was also provided by the MED-FORESTSTREAMS (CGL2011-30590-C02-01) project. A. P. was supported by a Formación de Personal Investigador Ph.D. fellowship from the Spanish Ministry of Science and Innovation within the context of ISONEF (CGL2008-05504-C02-01).
Publisher Copyright:
© 2014, Springer-Verlag Berlin Heidelberg.
PY - 2014/12
Y1 - 2014/12
N2 - Leaf litter decomposition plays a major role in nutrient dynamics in forested streams. The chemical composition of litter affects its processing by microorganisms, which obtain nutrients from litter and from the water column. The balance of these fluxes is not well known, because they occur simultaneously and thus are difficult to quantify separately. Here, we examined C and N flow from streamwater and leaf litter to microbial biofilms during decomposition. We used isotopically enriched leaves (13C and 15N) from two riparian foundation tree species: fast-decomposing Populus fremontii and slow-decomposing Populus angustifolia, which differed in their concentration of recalcitrant compounds. We adapted the isotope pool dilution method to estimate gross elemental fluxes into litter microbes. Three key findings emerged: litter type strongly affected biomass and stoichiometry of microbial assemblages growing on litter; the proportion of C and N in microorganisms derived from the streamwater, as opposed to the litter, did not differ between litter types, but increased throughout decomposition; gross immobilization of N from the streamwater was higher for P. fremontii compared to P. angustifolia, probably as a consequence of the higher microbial biomass on P. fremontii. In contrast, gross immobilization of C from the streamwater was higher for P. angustifolia, suggesting that dissolved organic C in streamwater was used as an additional energy source by microbial assemblages growing on slow-decomposing litter. These results indicate that biofilms on decomposing litter have specific element requirements driven by litter characteristics, which might have implications for whole-stream nutrient retention.
AB - Leaf litter decomposition plays a major role in nutrient dynamics in forested streams. The chemical composition of litter affects its processing by microorganisms, which obtain nutrients from litter and from the water column. The balance of these fluxes is not well known, because they occur simultaneously and thus are difficult to quantify separately. Here, we examined C and N flow from streamwater and leaf litter to microbial biofilms during decomposition. We used isotopically enriched leaves (13C and 15N) from two riparian foundation tree species: fast-decomposing Populus fremontii and slow-decomposing Populus angustifolia, which differed in their concentration of recalcitrant compounds. We adapted the isotope pool dilution method to estimate gross elemental fluxes into litter microbes. Three key findings emerged: litter type strongly affected biomass and stoichiometry of microbial assemblages growing on litter; the proportion of C and N in microorganisms derived from the streamwater, as opposed to the litter, did not differ between litter types, but increased throughout decomposition; gross immobilization of N from the streamwater was higher for P. fremontii compared to P. angustifolia, probably as a consequence of the higher microbial biomass on P. fremontii. In contrast, gross immobilization of C from the streamwater was higher for P. angustifolia, suggesting that dissolved organic C in streamwater was used as an additional energy source by microbial assemblages growing on slow-decomposing litter. These results indicate that biofilms on decomposing litter have specific element requirements driven by litter characteristics, which might have implications for whole-stream nutrient retention.
KW - Immobilization
KW - Nutrient cycling
KW - Populus
KW - Recalcitrant compounds
UR - http://www.scopus.com/inward/record.url?scp=84920954519&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84920954519&partnerID=8YFLogxK
U2 - 10.1007/s00442-014-3063-y
DO - 10.1007/s00442-014-3063-y
M3 - Article
C2 - 25214242
AN - SCOPUS:84920954519
SN - 0029-8519
VL - 176
SP - 1111
EP - 1121
JO - Oecologia
JF - Oecologia
IS - 4
ER -