『Abstract
This study investigates soil N2O dynamics
in forest soils representing early (3-years) and late (＞50 years)
post-harvest succession in Atlantic Canada over a 9-month snow-free
period in order to develop a better understanding of the role
of managed forests as sources and sinks of N2O.
We couple measurement of surface flux with detailed measurements
of subsurface N2O concentrations at four
mineral soil depths (0, 5, 20 and 35 cm) at 40 plots located within
four sites. Median surface fluxes were similar at all sites regardless
of the management stage (-5 to +19 μgN2O-N/m2/day),
with all sites behaving as net sinks and sources of N2O
over the measurement period. Subsurface mineral soil N2O
concentrations at early (3-year) post-harvest succession sites,
which ranged from median values of 362 ppbv at 0 cm to 1783 ppbv
at 35 cm depth, were significantly higher than late post-harvest
succession sites where median concentrations ranged from 329 ppbv
at 0 cm to 460 ppbv at 35 cm depth. Examination of relationships
between subsurfaces gas storage and surface flux magnitudes, suggested
although recently harvested forest soils may be producing N2O at a greater rate than mature forest soils,
observed patterns are consistent with a strong sink for this gas
that prevents its conservative transport through the soil profile,
and ultimate emission to the atmosphere through the majority of
the measurement period.
Keywords: Nitrous oxide; Forest management; Greenhouse gases;
Climate change』
Introduction
Study site and methods
Meteorological stations
Gas sampling, design and analysis
Data analysis
Results
Surface flux: temporal patterns and relationships to soil
temperature and moisture
Patterns of subsurface soil N2O concentrations
Coupled N2O surface flux and subsurface
concentration data
Discussion and conclusions
N2O surface fluxes: magnitudes and relationships
to temperature and moisture
Subsurface soil air N2O concentration trends
Coupling subsurface soil air concentrations and surface fluxes
Acknowledgments
References