Methane and nitrous oxide fluxes of soils in pure and mixed stands of European beech and Norway spruce

Abstract

Tree species can affect the sink and source strength of soils for atmospheric methane and nitrous oxide. Here we report soil methane (CH 4 ) and nitrous oxide (N 2 O) fluxes of adjacent pure and mixed stands of beech and spruce at Solling, Germany. Mean CH 4 uptake rates ranged between 18 and 48 mg C m ÿ2 hour ÿ1 during 2.5 years and were about twice as great in both mixed and the pure beech stand as in the pure spruce stand. CH 4 uptake was negatively correlated with the dry mass of the O horizon, suggesting that this diminishes the transport of atmospheric CH 4 into the mineral soil. Mean N 2 O emission was rather small, ranging between 6 and 16 mg N m ÿ2 hour ÿ1 in all stands. Forest type had a significant effect on N 2 O emission only in one mixed stand during the growing season. We removed the O horizon in additional plots to study its effect on gas fluxes over 1.5 years, but N 2 O emissions were not altered by this treatment. Surprisingly, CH 4 uptake decreased in both mixed and the pure beech stands following the removal of the O horizon. The decrease in CH 4 uptake coincided with an increase in the soil moisture content of the mineral soil. Hence, O horizons may maintain the gas diffusivity within the mineral soil by storing water which cannot penetrate into the mineral soil after rainfall. Our results indicate that conversion of beech forests to beech-spruce and pure spruce forests could decrease soil CH 4 uptake, while the long-term effect on N 2 O emissions is expected to be rather small.

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

“…This is in good agreement with previous observations (e.g. fluxes reported from several field measurements for temperate coniferous forests in Europe Borken et al, 2000Borken et al, , 2003Borken and Beese, 2006). However, consumption was lower than in some studies of temperate coniferous forests in North America (Yavitt et al, 1990;Castro et al, 1992;Gulledge et al, 2004).…”

Winter greenhouse gas fluxes (CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O) from a subalpine grassland

“…CH 4 fluxes measured in this study correlated moderately with soil temperature but showed no strong relationship with soil moisture (not shown). Although volumetric soil water content of the soil is one crucial factor limiting CH 4 diffusion into soils (Wang et al, 2010(Wang et al, , 2005Borken and Beese, 2006;Chen et al, 2011a, b;Hartmann et al, 2011), Chen et al (2011a found that this is only valid for soil temperatures > 5 • C. Soil temperatures above 5 • C were only observed after snowmelt at our site (Fig. 2b).…”

Variability of soil N cycling and N2O emission in a mixed deciduous forest with different abundance of beech

“…These values were comparable to the estimated N 2 O emission from deciduous forest soils in Germany with an average of 0.37 kg N 2 O-N ha −1 yr −1 (SchulteBisping et al 2003). Studies have shown that emissions were smaller in coniferous stands than in broadleaf stands (Butterbach-Bahl et al 1998;Butterbach-Bahl et al 2002;Borken and Beese 2006), which were suggested to be caused by smaller gross rates of N mineralization and nitrification in coniferous than broadleaf stands (Ambus et al 2006). There is little information on the influence of different deciduous tree species on N 2 O emission.…”