Abstract
Increasing concentrations of atmospheric greenhouse gases (GHGs;
CO2, CH4, N2O) causes
climate change. Depending on the conditions, soils have the potential to
store carbon or to be a source of GHGs to the atmosphere. Riparian soils
in particular have high potential to store carbon, but also to be
sources of CH4 and N2O. Headwater
streams make up a large proportion of stream length in a drainage
network, and their riparian zones have valuable ecosystem functions. In
parallel, the riparian zones of headwater streams are particularly
vulnerable to forest harvest. Studies of GHG fluxes from these unique
ecosystems remain limited. Our objective was to quantify the effects of
forestry practices and groundwater discharge (DIS) areas on GHG
emissions from riparian forest soils in coastal British Columbia. We
compared nine sites with three different forest management protocols: 1)
harvesting with a riparian buffer, 2) no buffer, and 3) reference sites
without harvesting. We measured gas fluxes, soil temperature, soil
moisture and depth to the groundwater table alongside headwater streams
monthly over one growing season. We found that CH4uptake rates were 65% lower at the no buffer sites, and
N2O emission rates were 52% lower at the no buffer
sites, when compared to the reference sites. Additionally,
CH4 uptake was 54% lower at DIS areas than in non-DIS
areas. The results of our research help inform forest management by
demonstrating that maintaining riparian buffers can be effective in
protecting the ecosystem functions contributing to soil GHG fluxes.