Abstract
The magnitude of CO
2 flux from soil (F
soil) varies with primary productivity and environmental drivers of respiration, soil temperature (T
soil) and moisture, all of which vary temporally and spatially. To quantify the sources of F
soil variability, we first compared F
soil of three proximate forests within 30 km of one another, ranging in age, composition, soil, and environment and, thus, productivity. We collected data with automated soil respiration chambers during a 10-year period in a mid-rotation
Pinus taeda plantation (PP), for three-years in a mature
P. taeda stand (OP), and for five-years in a mature, mixed-species hardwood (HW) stand; PP and HW were on clay-loam soil and OP on a sandy soil. Among stands, F
soil sensitivity to T
soil was lowest in OP and highest in PP, reflected in mean annual F
soil (±standard deviation) of 1033 ± 226 (OP), 1206 ± 99 (HW), and 1383 ± 152 (PP) g C m²; both F
soil sensitivity to T
soil and annual F
soil increased with leaf litterfall. For the second portion of our study, we established an additional three plots at PP for a six-year period to examine within-stand variability. Within PP, sensitivity of F
soil to T
soil was similar, yet higher leaf area was correlated with a combination of lower soil temperature and below-ground carbon flux, resulting in lower F
soil. Temporally, diurnal to seasonal F
soil followed T
soil whereas annual values were driven by soil moisture. Spatially, among the three stands F
soil increased with leaf production, whereas within a stand (PP) F
soil decreased with increasing leaf production.
Keywords
Automated soil respiration chambers,
Belowground carbon flux,
Deciduous,
Drought,
Evergreen,
Litterfall
Citation
Oishi, A. Christopher; Palmroth, Sari; Butnor, John R.; Johnsen, Kurt H.; Oren, Ram. 2013. Spatial and temporal variability of soil CO2 efflux in three proximate temperate forest ecosystems. Agricultural and Forest Meteorology 171-172:256-269.