Carbon and Nitrogen Pools and Fluxes in Adjacent Mature Norway Spruce and European Beech Forests

Abstract

Abstract:We compared two adjacent mature forest ecosystem types (spruce vs. beech) to unravel the fate of assimilated carbon (C) and the cycling of organic and inorganic nitrogen (N) without the risk of the confounding influences of climatic and site differences when comparing different sites. The stock of C in biomass was higher (258 t·ha −1 ) in the older (150 years) beech stand compared to the younger (80 years) planted spruce stand (192 t·ha −1 ), whereas N biomass pools were comparable (1450 kg·ha −1 ). Significantly higher C and N soil pools were measured in the beech stand, both in forest floor and mineral soil. Cumulative annual CO 2 soil efflux was similar among stands, i.e., 9.87 t·ha −1 ·year −1 of C in the spruce stand and 9.01 t·ha −1 ·year −1 in the beech stand. Soil temperature explained 78% (Q 10 = 3.7) and 72% (Q 10 = 4.2) of variability in CO 2 soil efflux in the spruce and beech stand, respectively. However, the rather tight N cycle in the spruce stand prevented inorganic N losses, whereas losses were higher in the beech stand and were dominated by nitrate in the mineral soil. Our results highlighted the long-term consequences of forest management on C and N cycling.

Comparison of the impacts of acid and nitrogen additions on carbon fluxes in European conifer and broadleaf forests

“…The measured respiration decline of 6% -10% under S treatment is similar to that found in a recent meta-analysis (7%) based on experiments from China (Feng et al, 2017). The reduction of CO2 effluxes under S treatment corresponds to the 27% -49% of annual litter production (aboveground litterfall of 1937 kg C ha -1 year -1 between 2013-2016, Oulehle et al, 2016b). Based on a total S addition of 50 kg S ha -1 year -1 this corresponds to the suppression of decomposition by 10.6 to 19 kg C kg S -1 .…”

“…and mature European beech forest (Fagus sylvatica L.). The spruce stand consists of Norway spruce monoculture planted in the early 1930s, and the beech stand consists of European beech monoculture (Oulehle et al, 2016b). The distance between stands is approximately 1 km and both stands are underlined by gneiss bedrock.…”

“…; Oulehle et al 2011Oulehle et al , 2016b. Ground cover vegetation in the spruce stand (60%) is formed mainly by Avenella flexuosa L. Drejer with admixture of Vaccinium myrtillus L., Dryopteris dilatata (Hoffm.)…”

“…Measured total soil respiration (Rs) rates were closely related to the seasonal course of soil temperature, and soil temperature was the overriding control on temporal variation in Rs, with limited effects of soil moisture (Oulehle et al, 2016b). A large part of Rs in forests is derived from autotrophic respiration (Högberg et al, 2001), thus detection of subtle changes in soil CO2 effluxes, driven by heterotrophic decomposition of fresh litter and SOM, is difficult.…”

Input-Output Budgets of Nutrients in Adjacent Norway Spruce and European Beech Monocultures Recovering from Acidification

“…Iost et al [14] reported an exceedance of critical limits in DIN (N- ). This stands in contrast to studies reporting higher N leaching under spruce [38,42] as a result of higher deposition of N. However, a comparison of the C/N ratio of the two organic horizons [25] revealed a lower C/N ratio in the FH horizon under beech (beech stand: 19.9 vs. spruce stand: 23.3). According to Gundersen et al [51], when the C/N ratio is less than or equal to 25, there is a high probability that leaching will occur.…”