Abstract
Abstract. Besides agricultural soils, temperate forest soils have been identified as significant sources of or sinks for important atmospheric trace gases (N2O, NO, CH4, and CO2). Although the number of studies for this ecosystem type increased more than tenfold during the last decade, studies covering an entire year and spanning more than 1–2 years remained scarce. This study reports the results of continuous measurements of soil-atmosphere C- and N-gas exchange with high temporal resolution carried out since 1994 at the Höglwald Forest spruce site, an experimental field station in Southern Germany. Annual soil N2O, NO and CO2 emissions and CH4 uptake (1994–2010) varied in a range of 0.2–3.0 kg N2O-N ha−1yr−1, 6.4–11.4 kg NO-N ha−1yr−1, 7.0–9.2 t CO2-C ha−1yr−1, and 0.9–3.5 kg CH4-C ha−1yr−1, respectively. The observed high fluxes of N-trace gases are most likely a consequence of high rates of atmospheric nitrogen deposition (>20 kg N ha−1yr−1) of NH3 and NOx to our site. For N2O, cumulative annual emissions were ≥ 0.8 kg N2O-N ha−1yr−1 in years with freeze-thaw events (5 out 14 of years). This shows that long-term, multi-year measurements are needed to obtain reliable estimates of N2O fluxes for a given ecosystem. Cumulative values of soil respiratory CO2 fluxes tended to be highest in years with prolonged freezing periods, i.e. years with below average annual mean soil temperatures and high N2O emissions (e.g. the years 1996 and 2006). Furthermore, based on our unique database on trace gas fluxes we analyzed if soil temperature, soil moisture measurements can be used to approximate trace gas fluxes at daily, weekly, monthly, or annual scale. Our analysis shows that simple-to-measure environmental drivers such as soil temperature or soil moisture are suitable to approximate fluxes of NO and CO2 at weekly and monthly resolution reasonably well (accounting for up to 59 % of the variance). However, for CH4 we so far failed to find meaningful correlations, and also for N2O the predictive power is rather low. This is most likely due to the complexity of involved processes and counteracting effects of soil moisture and temperature, specifically with regard to N2O production and consumption by denitrification and microbial community dynamics. At monthly scale, including information on gross primary production (CO2, NO), and N deposition (N2O), increased significantly the explanatory power of the obtained empirical regressions (CO2: r2 =0.8; NO: r2 = 0.67; N2O, all data: r2 = 0.5; N2O, with exclusion of freeze-thaw periods: r2 = 0.65).
Highlights
Based on an ISI search, studies on trace gas exchange between temperate forest soils and the atmosphere have increased by a factor of 12 from the decade 1990–2000 to the decade 2001–2010
Hoglwald Forest is situated in the temperate suboceanic broadleaf zone in the south of Germany
Fluxes of trace gases were measured with automated static or dynamic chamber systems at an approx. 100 yrs old spruce forest site in subdaily resolution between 1994 and 2010
Summary
Temperate forest soils are significant sources of the primarily and secondarily greenhouse gases CO2, N2O and NO (Brumme and Beese, 1992; Castro et al, 1993; ButterbachBahl et al, 1998; van Dijk and Duyzer, 1999; Pilegaard et al, 2006; Phillips et al, 2010), and significant sinks for atmospheric CH4 (Borken and Brumme, 1997; Henckel et al, 2000; Smith et al, 2000; Brumme and Borken, 1999; Butterbach-Bahl and Papen, 2002; Borken and Beese, 2006). Based on an ISI search, studies on trace gas exchange between temperate forest soils and the atmosphere have increased by a factor of 12 from the decade 1990–2000 to the decade 2001–2010. Luo et al.: Decadal variability of soil CO2, NO, N2O, and CH4 fluxes of the biogeochemical N and C turnover processes and the temporal variability of trace gas fluxes on daily to multi-year scales
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
