Environmental controls over soil‐atmosphere exchange of N₂O, NO, and CO₂ in a temperate Norway spruce forest

Abstract

[1] Trace gas exchange of N 2 O, NO, and CO 2 between soil and the atmosphere was measured with high temporal resolution for 5 years (2004)(2005)(2006)(2007)(2008) at the Höglwald Forest, Germany, using a fully automated measuring system. On the basis of these long-term continuous measurements, we calculated the annual budgets of soil-atmosphere trace gas , and 7.15 ± 0.08 t CO 2 -C ha −1 yr −1 , respectively. Seasonal patterns of soil N 2 O fluxes were characterized by event emissions, generally occurring during thawing after longer freezing periods. In contrast to N 2 O emissions, the seasonal patterns of NO and CO 2 soil-atmosphere exchange followed soil temperature changes, although a substantial increase in CO 2 emissions was also observed during the freeze and thaw periods. The fact that NO fluxes were higher than N 2 O emissions during most of the entire observation period indicated that nitrification might have been the primary pathway of N-trace gas production in our study. The extremely high N 2 O emissions and the substantial interannual variation of N 2 O flux rates caused by the freeze and thaw effect demonstrate the need for long-term measurements with high temporal resolution in order to come up with more reliable estimates of soil-atmosphere trace fluxes.

Decadal variability of soil CO<sub>2</sub>, NO, N<sub>2</sub>O, and CH<sub>4</sub> fluxes at the Höglwald Forest, Germany

“…The soil pH value (measured in 0.1 M CaCl 2 ) is 2.9-3.2 in the organic layer and 3.6-4.0 in the uppermost mineral soil layer (Kreutzer, 1995). Further information about the Höglwald Forest site can be found in Kreutzer (1995), Kreutzer and Weiss (1998), ButterbachBahl et al (2002) or Wu et al (2010).…”

“…Moreover, this dataset has never been evaluated with regard to multi-year relationships between soil environmental parameters such as soil moisture, temperature, precipitation, N deposition as measured in throughfall, or gross primary production and soil trace gas fluxes. Also inter-relationships between individual C-and N-trace gases have hardly been evaluated so far, except for the study of Wu et al (2010), with the latter study only using less than one-third of the full dataset. Therefore the main objectives of this study are, 1. to summarize 15 years of continuous trace gas measurements at Höglwald Forest and to evaluate seasonal and interannual variability of fluxes, 2. to use the multi-year dataset to elucidate relationships between environmental parameters and soil trace gas fluxes, 3. to test if easy-to-measure environmental parameters such as soil moisture and soil temperature can be used to approximate trace gas fluxes at weekly, monthly or annual time scales.…”

“…Among these parameters, soil moisture and temperature are identified as key drivers for soil-atmosphere exchange in many field investigations (e.g. Gasche and Papen, 1999;Papen and Butterbach-Bahl, 1999;Borken et al, 2002;Wu et al, 2010) and process studies (e.g. Schindlbacher et al, 2004).…”

Long-term effects of clear-cutting and selective cutting on soil methane fluxes in a temperate spruce forest in southern Germany

“…The required input data, creation of the training dataset and prediction of soil water content were described in detail by Wu et al (2010a). Soil moisture values were converted to percent water-filled pore space (% WFPS) according to Wu et al (2010a). Climatic data were obtained from the German Weather Service station Augsburg-Mühlhausen, which was about 20 km northwest from our study site.…”

“…The SVM method is based on a statistical learning algorithm and has been successfully applied to bioinformatics, flood forecasting and soil water prediction (Furey et al, 2000;Chen and Yu, 2007;Wu et al, 2010a). The required input data, creation of the training dataset and prediction of soil water content were described in detail by Wu et al (2010a). Soil moisture values were converted to percent water-filled pore space (% WFPS) according to Wu et al (2010a).…”