Soil Properties and Trace Gas Fluxes in a Newly-Restored Riparian Forest.
Pierre-Andre Jacinthe, Lenore Tedesco, and Robert C. Barr. IUPUI, Dept of Earth Sciences, 723 W Michigan St, SL 122, Indianapolis, IN 46202
Although the contribution of riparian forests to stream water quality is well documented,
information is lacking with regard to the exchange of trace gases between riparian soils and the
atmosphere. This information is important given the implication of trace gases (CO2, N2O and
CH4) in the accelerated greenhouse effect. Soil properties and gas emission were measured at
experimental riparian forest plots (5 years after restoration) established along the White River
near Indianapolis. The study site included afforested plots and unplanted controls. The highest
CO2 (3.2 vs 1.8 mg CO2-C m2 d-1) and N2O (1.04 vs 0.52 mg N2O-N m2 d-1 ) fluxes were recorded
in the summer and early spring, and fluxes were generally higher (1.7 fold) close to than away
from the river margin. The riparian soils were generally net CH4 sink with uptake rates
averaging -0.26 and -0.44 mg CH4-C m2 d-1 in the control and afforested plots, respectively. The
lowest uptake rates were recorded during the transition from winter to spring and, during that
period, negative relationships between CO2 and CH4 fluxes were noted. These results highlight
the complexity of trace gas dynamics in riparian zones, and will be discussed along with soil
biophysical properties, flooding events and variation in water table position at the study site.