Carbon and nitrogen stoichiometry and nitrogen cycling rates in streams.
Stoichiometric analyses can be used to investigate the linkages between N and C cycles and how these linkages influence biogeochemistry at many scales, from components of individual ecosystems up to the biosphere. N-specific NH4+ uptake rates were measured in eight streams using short-term 15N tracer additions, and C to N ratios (C:N) were determined from living and non-living organic matter collected from ten streams. These data were also compared to previously published data compiled from studies of lakes, ponds, wetlands, forests, and tundra. There was a significant negative relationship between C:N and N-specific uptake rate; C:N could account for 41% of the variance in N-specific uptake rate across all streams, and the relationship held in five of eight streams. Most of the variation in N-specific uptake rate was contributed by detrital and primary producer compartments with large values of C:N and small values for N-specific uptake rate. In streams, particulate materials are not as likely to move downstream as dissolved N, so if N is cycling in a particulate compartment, N retention is likely to be greater. Together, these data suggest that N retention may depend in part on C:N of living and non-living organic matter in streams. Factors that alter C:N of stream ecosystem compartments, such as removal of riparian vegetation or N fertilization, may influence the amount of retention attributed to these ecosystem compartments by causing shifts in stoichiometry. Our analysis suggests that C:N of ecosystem compartments can be used to link N-cycling models across streams.
Dodds
Walter K
WK
Division of Biology, Kansas State University, Manhattan, KS 66506, USA. wkdodds@ksu.edu
Martí
Eugenia
E
Tank
Jennifer L
JL
Pontius
Jeffrey
J
Hamilton
Stephen K
SK
Grimm
Nancy B
NB
Bowden
William B
WB
McDowell
William H
WH
Peterson
Bruce J
BJ
Valett
H Maurice
HM
Webster
Jackson R
JR
Gregory
Stan
S
D002244:Carbon / Q000378:metabolism*; D017753:Ecosystem; D004784:Environmental Monitoring; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes / Q000032:analysis; D045483:Rivers
D009587:Nitrogen Isotopes; D002244:Carbon; D009584:Nitrogen