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

Abstract

The mixture of other broadleaf species into beech forests in Central Europe leads to an increase of tree species diversity, which may alter soil biochemical processes. This study was aimed at 1) assessing differences in gross rates of soil N cycling among deciduous stands of different beech (Fagus sylvatica L.) abundance in a limestone area, 2) analyzing the relationships between gross rates of soil N cycling and forest stand N cycling, and 3) quantifying N 2 O emission and determining its relationship with gross rates of soil N cycling. We used 15 N pool dilution techniques for soil N transformation measurement and chamber method for N 2 O flux measurement. Gross rates of mineral N production in the 0-5 cm mineral soil increased across stands of decreasing beech abundance and increasing soil clay content. These rates were correlated with microbial biomass which, in turn, was influenced by substrate quantity, quality and soil fertility. Leaf litter-N, C:N ratio and base saturation in the mineral soil increased with decreasing beech abundance. Soil mineral N production and assimilation by microbes were tightly coupled, resulting in low N 2 O emissions. Annual N 2 O emissions were largely contributed by the freezethaw event emissions, which were correlated with the amount of soil microbial biomass. Our results suggest that soil N availability may increase through the mixture of broadleaf species into beech forests.

Soil water content drives spatiotemporal patterns of CO<sub>2</sub> and N<sub>2</sub>O emissions from a Mediterranean riparian forest soil

“…Nevertheless, we also expected a fast N cycle as well as large N 2 O emissions following rains in November because, similarly to spring, environmental conditions (i.e., high soil water content and increments in soil NO − 3 concentrations during the antecedent dry summer) should enhance microbial activity. Likely, low rates of N transformations during fall may be attributed to an increase in microbial N demand following large C inputs from litterfall (Guckland et al, 2010). Moreover, leaf litter from R. pseudoacacia, the main tree species in our study site, holds a high lignin content (Castro-Díez et al, 2009;Yavitt et al, 1997), which might enrich the riparian soil with phenolic compounds and ultimately limit the use of N by microbes (Bardon et al, 2014).…”

Effects of soil rewetting and thawing on soil gas fluxes: a review of current literature and suggestions for future research

“…Increase of N 2 O flux following thawing in forest (4180 %) is higher than those of cropland, grassland and other ecosystems (750-1760 %; Table 2). Thaw-induced N 2 O fluxes constituted a major component of annual N 2 O fluxes from arable field (Regina et al, 2004;Johnson et al, 2010), temperate grassland (Kammann et al, 1998;Müller et al, 2002), steppe (Holst et al, 2008;, wetland (Yu et al, 2007) and forest ecosystems (Papen and Butterbach-Bahl, 1999;Wu et al, 2010a;Guckland et al, 2010), with contributions exceeding 50 % of the annual budget in some years.…”

Process‐based TRIPLEX‐GHG model for simulating N2O emissions from global forests and grasslands: Model development and evaluation

“…For certain data sets that yielded small values (approximately 0.03 mg N m −2 d −1 on average in Guckland et al . [] (Figure c) and Klemedtsson et al . [] (Figure h)), the model was also able to capture their general trends, although the measurements exhibited sudden increases and decreases.…”

“…We also averaged soil information, such as soil texture, soil pH, and SOC, from these sites to force the model. For data from the same location that have large gaps, we retained all data for calibration [ Guckland et al ., ; Jungkunst et al ., ]. We measured the data from studies by Butterbach‐Bahl et al .…”