An annual organic carbon budget is presented for an 8-km segment of Creeping Swamp, an undisturbed, third-order swamp-stream in the Coastal Plain of North Carolina, USA. Annual input of organic carbon (588 gC/m2) was 96% allochthonous and was dominated by leaf litter inputs (36%) and fluvial, dissolved organic carbon (DOC) inputs (31%). Although the swamp-stream was primarily heterotrophic, autochthonous organic carbon input, primarily from filamentous algae, was important during February and March when primary production/ecosystem respiration (P/R) ratios of the flooded portions were near one. Annual output of organic carbon via fluvial processes (214 gC/m2), 95% as DOC, was 36% of total annual inputs, indicating that the swamp-stream segment ecosystem was 64% efficient at retaining organic carbon. Respiration (327 gC/m2) accounted for most of this retention, or about 57% of annual inputs, and storage accounted for the remaining 7% of inputs. Organic carbon dynamics in the Creeping Swamp segment were compared to those reported for upland stream segments using indices of organic matter processing suggested by Fisher (1977) and a loading potential index suggested here. Creeping Swamp, while loading at a high rate, retains a much larger portion of its organic carbon inputs than two upland streams. Organic carbon loading potential in Creeping Swamp is very large, primarily because of its great width and complete canopy; however, its low gradient and dense vegetation enhance organic carbon retention, especially of coarse partic- ulate organic carbon (CPOC), by maintaining low water velocities with little erosive force, tortuous flow pathways, and debris dams. Most of the retention and oxidation of organic carbon in the flooded Creeping Swamp ecosystem takes place in the floodplain. It is suggested that floodplain exchanges should also be considered in budgets of higher gradient rivers and streams. Despite the high degree of retention and oxidation of organic inputs to Creeping Swamp, there is a net annual fluvial export of 21 gC/m2, mostly in the dissolved form. Watersheds drained by swamp- streams in the southeastern United States are thought to have large organic carbon exports compared to upland forested drainages, because the stream network covers a much greater proportion of the total watershed area.
[1]
D. Menzel,et al.
The Measurement of Dissolved Organic and Particulate Carbon in SEAWATER1
,
1964
.
[2]
G. Likens,et al.
Effect of hydrologic fluctuations on the transport of fine particulate organic carbon in a small stream1
,
1979
.
[3]
H. Lieth,et al.
STUDIES ON THE VEGETATION OF THE GASPÉ PENINSULA: II. THE SOIL RESPIRATION OF SOME PLANT COMMUNITIES
,
1962
.
[4]
H. Odum.
Primary Production in Flowing Waters1
,
1956
.
[5]
P. Mulholland,et al.
Organic carbon export from upland and forested wetland watersheds1
,
1979
.
[6]
H. D. Bradshaw,et al.
Litterfall, stemflow, and throughfall nutrient fluxes in an alluvial swamp forest.
,
1980
.
[7]
J. D. Helvey,et al.
Canopy and litter interception of rainfall by hardwoods of eastern United States
,
1965
.
[8]
Robert C. Petersen,et al.
Leaf processing in a woodland stream
,
1974
.
[9]
M. Klug,et al.
Fungi and Bacteria Associated with Leaves During Processing in a Woodland Stream
,
1976
.
[10]
Gene E. Likens,et al.
Energy Flow in Bear Brook, New Hampshire: An Integrative Approach to Stream Ecosystem Metabolism
,
1973
.
[11]
N. Edwards,et al.
Carbon Cycling in a Mixed Deciduous Forest Floor
,
1977
.
[12]
F. Bärlocher,et al.
Assimilation Efficiency of Gammarus pseudolimnaeus (Amphipoda) Feeding on Fungal Mycelium or Autumn-Shed Leaves
,
1975
.
[13]
F. O. Howard,et al.
Organic Enrichment with Leaf Leachate in Experimental Lotic Ecosystems
,
1972
.
[14]
H. Hynes,et al.
THE FORMATION OF PARTICLES IN FRESHWATER LEACHATES OF DEAD LEAVES1
,
1973
.
[15]
G. Wayne Mninshall,et al.
Role of Allochthonous Detritus in the Trophic Structure of a Woodland Springbrook Community
,
1967
.
[16]
D. Blanchard.
Bubble Scavenging and the Water-to-Air Transfer of Organic Material in the Sea
,
1975
.
[17]
George E. Claypool,et al.
The Origin and Distribution of Methane in Marine Sediments
,
1974
.
[18]
B. Copeland,et al.
USE OF A CLEAR PLASTIC DOME TO MEASURE GASEOUS DIFFUSION RATES IN NATURAL WATERS
,
1964
.
[19]
Gene E. Likens,et al.
Stream ecosystem: Organic energy budget
,
1972
.