scholarly journals The linkage of 13C and 15N soil depth gradients with C:N and O:C stoichiometry reveals tree species effects on organic matter turnover in soil

2020 ◽  
Vol 151 (2-3) ◽  
pp. 203-220
Author(s):  
Marcel Lorenz ◽  
Delphine Derrien ◽  
Bernd Zeller ◽  
Thomas Udelhoven ◽  
Willy Werner ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tree Species ◽  
Soil Depth ◽  
Mineral Soil ◽  
European Beech ◽  
Pinus Nigra ◽  
Deciduous Tree ◽  
Elemental Stoichiometry ◽  
Depth Gradients

AbstractThe knowledge of tree species dependent turnover of soil organic matter (SOM) is limited, yet required to understand the carbon sequestration function of forest soil. We combined investigations of 13C and 15N and its relationship to elemental stoichiometry along soil depth gradients in 35-year old monocultural stands of Douglas fir (Pseudotsuga menziesii), black pine (Pinus nigra), European beech (Fagus sylvatica) and red oak (Quercus rubra) growing on a uniform post-mining soil. We investigated the natural abundance of 13C and 15N and the carbon:nitrogen (C:N) and oxygen:carbon (O:C) stoichiometry of litterfall and fine roots as well as SOM in the forest floor and mineral soil. Tree species had a significant effect on SOM δ13C and δ15N reflecting significantly different signatures of litterfall and root inputs. Throughout the soil profile, δ13C and δ15N were significantly related to the C:N and O:C ratio which indicates that isotope enrichment with soil depth is linked to the turnover of organic matter (OM). Significantly higher turnover of OM in soils under deciduous tree species depended to 46% on the quality of litterfall and root inputs (N content, C:N, O:C ratio), and the initial isotopic signatures of litterfall. Hence, SOM composition and turnover also depends on additional—presumably microbial driven—factors. The enrichment of 15N with soil depth was generally linked to 13C. In soils under pine, however, with limited N and C availability, the enrichment of 15N was decoupled from 13C. This suggests that transformation pathways depend on litter quality of tree species.

scholarly journals Density fractions versus size separates: does physical fractionation isolate functional soil compartments?

2012 ◽  
Vol 9 (12) ◽  
pp. 5181-5197 ◽  
Author(s):  
C. Moni ◽  
D. Derrien ◽  
P.-J. Hatton ◽  
B. Zeller ◽  
M. Kleber
Keyword(s):  
Organic Matter ◽  
Mineral Soil ◽  
European Beech ◽  
Nitrogen Dynamics ◽  
Protective Mechanism ◽  
Density Fractionation ◽  
Adsorbed State ◽  
Density Fractions ◽  
Physical Fractionation ◽  
Comprehensive Picture

Abstract. Physical fractionation is a widely used methodology to study soil organic matter (SOM) dynamics, but concerns have been raised that the available fractionation methods do not well describe functional SOM pools. In this study we explore whether physical fractionation techniques isolate soil compartments in a meaningful and functionally relevant way for the investigation of litter-derived nitrogen dynamics at the decadal timescale. We do so by performing aggregate density fractionation (ADF) and particle size-density fractionation (PSDF) on mineral soil samples from two European beech forests a decade after application of 15N labelled litter. Both density and size-based fractionation methods suggested that litter-derived nitrogen became increasingly associated with the mineral phase as decomposition progressed, within aggregates and onto mineral surfaces. However, scientists investigating specific aspects of litter-derived nitrogen dynamics are pointed towards ADF when adsorption and aggregation processes are of interest, whereas PSDF is the superior tool to research the fate of particulate organic matter (POM). Some methodological caveats were observed mainly for the PSDF procedure, the most important one being that fine fractions isolated after sonication can not be linked to any defined decomposition pathway or protective mechanism. This also implies that historical assumptions about the "adsorbed" state of carbon associated with fine fractions need to be re-evaluated. Finally, this work demonstrates that establishing a comprehensive picture of whole soil OM dynamics requires a combination of both methodologies and we offer a suggestion for an efficient combination of the density and size-based approaches.

scholarly journals Biomass of Coarse Woody Debris Following Fire and Clearcutting in Lodgepole Pine Forests

1997 ◽  
Vol 21 ◽  
pp. 33-35
Author(s):  
Dennis Knight ◽  
Daniel Tinker
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Coarse Woody Debris ◽  
Significant Contribution ◽  
Woody Debris ◽  
Mineral Soil ◽  
Primary Source ◽  
Timber Harvesting ◽  
Micro Organisms

In forest ecosystems, the decomposition of coarse woody debris, woody roots, twigs, leaves and micro-organisms is a primary source of mineral soil organic matter. Primary productivity, the accumulation of nutrients, and other important ecosystem processes are largely dependent on the mineral soil organic matter that has developed during hundreds or thousands of years. Large quantities of coarse woody debris are typically produced following natural disturbances such as fires, pest/pathogen outbreaks, and windstorms, and make a significant contribution to the formation of soil organic matter (SOM). In contrast, timber harvesting often removes much of the coarse woody debris (CWD), which could result in a decrease in the quantity and a change in the quality of mineral soil organic matter.

scholarly journals Age distribution, extractability, and stability of mineral-bound organic carbon in central European soils

2020 ◽  
Author(s):  
Marion Schrumpf ◽  
Klaus Kaiser ◽  
Allegra Mayer ◽  
Günter Hempel ◽  
Susan Trumbore
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Organic Carbon ◽  
Soil Depth ◽  
Age Distribution ◽  
Chemical Oxidation ◽  
Future Research ◽  
Soil Profiles ◽  
H2o2 Resistance ◽  
Depth Gradients

Abstract. The largest share of total soil organic carbon (OC) is associated with minerals. The portions and turnover of stable and faster cycling mineral-associated carbon (MOC) as well as the determining factors across different soils and soil depths are still unknown. Bioavailability of MOC is supposedly regulated by desorption but instead, its stability was so far mostly tested by exposure to chemical oxidation. Therefore, we determined the extractability of MOC into a mixture of 0.1 M NaOH and 0.4 M NaF as a measure for maximal potential desorbability, and compared it with maximal potential oxidation in heated H2O2. We selected samples of three soil depth increments (0–5 cm, 10–20 cm, 30–40 cm) of five typical soils of the mid-latitudes, differing contents of clay and pedogenic oxides, and being under different land use. Extracts and residues were analyzed for OC and 14C contents, and further chemically characterized by CPMAS-13C-NMR. We hypothesized NaF-NaOH extraction to remove less and younger MOC than H2O2 oxidation, and extractable MOC to be less and relatively older in subsoils and soils with high contents of pedogenic oxides. A surprisingly constant portion of 58 ± 11 % (standard deviation) of MOC was extractable across soils, independent of depths, mineral assemblage, or land use. NMR spectra revealed strong similarities of the extracted organic matter, with more than 80 % of OC in the O/N alkyl and alkyl C region. Total MOC amounts were linked to the content of pedogenic oxides across sites, independent of variations in total clay. The uniform MOC desorption could therefore be the result of pedogenic oxides dominating the overall response of MOC to extraction. While bulk MO14C values suggested differences in OC turnover between sites, these were not linked to differences in MOC extractability. As expected, OC contents of residues had smaller 14C contents than extracts, suggesting that non-extractable OC is older. However, 14C contents of extracts and residues were strongly correlated and proportional to bulk MO14C, but not dependent on mineralogy. Also along soil profiles, where increasing MOC ages indicate slower turnover with depth, neither MOC extractability nor differences in 14C between extracts and residues changed. Increasing bonding strength with soil depths did therefore not cause the 14C depth gradients in the studied soils. Although H2O2 removed 90 ± 8 % of the MOC, the 14C content of the OC removed was similar to that of the NaF-NaOH-extracted OC, while oxidation residues were much more 14C-depleted. Different chemical treatments apparently remove OC of the same continuum, leaving increasingly older residues behind the more OC being removed. Different from the extractions, higher contents of pedogenic oxides seemingly slightly increased the oxidation-resistance of MOC, but this higher H2O2-resistance did not coincide with older MOC or oxidation residues. Our results indicate that total MOC was dominated by OC interactions with pedogenic oxides rather than clay minerals, so that no difference in MOC extraction in NaF/NaOH, and thus, bond type or strength between clay-rich and poor sites was detectable. This suggests that site-specific differences in MO14C and their depth declines are driven by the accumulation and exchange rates of OC at mineral surfaces. Accordingly, future research on M14OC should focus on soil and ecosystem properties driving dissolved organic matter formation, composition and transport along soil profiles.

scholarly journals Soil Chemical Fertility Change Over 4 Decades In The Morvan Mountains And Influence of Tree Species (Burgundy, France)

2021 ◽  
Author(s):  
Clesse Margaux ◽  
Legout Arnaud ◽  
Ranger Jacques ◽  
Zeller Bernd ◽  
Van Der Heijden Gregory
Keyword(s):  
Tree Species ◽  
Soil Acidification ◽  
Mineral Soil ◽  
Chemical Properties ◽  
Common Garden ◽  
Pinus Nigra ◽  
Ecosystem Functions ◽  
Nutrient Pool ◽  
Atmospheric Depositions ◽  
Species Effect

Abstract Background: Intensive silvicultural practices and the planting of monospecific forests of coniferous, more productive compared to hardwoods, may threaten over the mid to long-term the sustainability of soil chemical fertility of forest ecosystems and is a major concern for forest managers and policy.Methods: We investigated the tree species effect (Quercus sessiliflora Smith, Fagus sylvatica L., Picea abies Karst., Pseudotsuga menziesii Mirb. Franco., Abies nordmanniana Spach. and Pinus nigra Arn. ssp laricio Poiret var corsicana) on the change over time of soil chemical properties and nutrient pool sizes in the mineral and organic layers of the soil during the 45 years after the plantation of the Breuil-Chenue common garden experiment (Burgundy, France). The organic and mineral soil layers down to 70 cm depth were sampled in the different monospecific plots in 1974, 2001 and 2019. Results: The Ca and Mg exchangeable pools and soil pH increased over the entire soil profile in most stands. However, the decrease of pH and the increase of exchange acidity in the topsoil layers under conifers and the overall decrease of exchangeable K pools in most stands highlighted that soil acidification is still on-going at this site but the intensity of this process depends on the tree species. Indeed, three groups of species could be distinguished: i) Nordmann fir / Norway spruce where acidolysis and chelation occurred, resulting in the most pronounced pH decrease in the topsoil, ii) Douglas fir / Laricio pine where acidification caused by elevated nitrification rates is probably currently compensated by larger weathering and/or atmospheric depositions fluxes, iii) and oak / beech where soil acidification was less intense. Counterintuitively, soil acidification at this site resulted in an increase in soil CEC which limited the loss of nutrient cations. This change in soil CEC was most likely explained by the precipitation/dissolution dynamics of aluminium (Al) (hydr)oxides in the interfoliar space of phyllosilicates and/or the increase in soil carbon (C) content in the topsoil layers. Conclusion: Tree species greatly and fairly rapidly (<45 years) influence the soil chemical fertility and the pedogenetic processes which in turn may impact forest ecosystem functions and services.

Admixing other tree species to European beech forests: Effects on soil organic carbon and total nitrogen stocks. A review.

2020 ◽  
Author(s):  
Stephanie Rehschuh ◽  
Michael Dannenmann
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Total Nitrogen ◽  
Tree Species ◽  
Forest Floor ◽  
Mineral Soil ◽  
European Beech ◽  
Summer Drought ◽  
Beech Forests ◽  
Soc Stocks

&lt;p&gt;Drought-sensitive European beech forests are increasingly challenged by climate change. Admixing other, preferably more deep-rooting, tree species has been proposed to increase the resilience of beech forests to summer drought. This might not only alter soil water dynamics and availability, but also soil organic carbon (SOC) and total nitrogen (TN) storage in soils. Since information of these effects is scattered, our aim was to synthesize results from studies that compared SOC/TN stocks of beech monocultures with those of mixed beech stands as well as of other monocultures. We conducted a meta-analysis including 40 studies with 208, 231 and 166 observations for forest floor, mineral soil and the total soil profile, respectively. Pure conifer stands had higher SOC stocks compared to beech in general, especially in the forest floor with up to 200% (larch forests). Other broadleaved tree species (ash, oak, lime, maple, hornbeam) showed in comparison to beech lower SOC storage in the forest floor, with little impact on total stocks. &amp;#160;Similarly, for mixed beech-conifer stands we found significantly increased SOC stocks of &gt;10% and a small increase in TN stocks of approx. 4% compared to beech monocultures, which means a potential SOC storage increase of &gt;0.1 t ha&lt;sup&gt;-1&lt;/sup&gt;yr&lt;sup&gt;-1 &lt;/sup&gt;(transformation of mineral soil to 100 cm depth). In contrast, mixed beech-broadleaved stands did not show a significant change in total SOC stocks. Currently, the influence climatic and soil parameters on SOC changes due to admixture of other tree species is analyzed based on this dataset. This is expected to facilitate an assessment which mixtures with beech have the largest potential towards increasing SOC stocks.&lt;/p&gt;

scholarly journals Dissolved organic matter characteristics of deciduous and coniferous forests with variable management: different at the source, aligned in the soil

2019 ◽  
Vol 16 (7) ◽  
pp. 1411-1432 ◽  
Author(s):  
Lisa Thieme ◽  
Daniel Graeber ◽  
Diana Hofmann ◽  
Sebastian Bischoff ◽  
Martin T. Schwarz ◽  
...  
Keyword(s):  
Organic Matter ◽  
Forest Management ◽  
Dissolved Organic Matter ◽  
Tree Species ◽  
Mineral Soil ◽  
Coniferous Forests ◽  
Management Intensity ◽  
Litter Leachate ◽  
Ft Icr Ms ◽  
Ft Icr

Abstract. Dissolved organic matter (DOM) is part of the biogeochemical cycles of carbon and nutrients, carries pollutants and drives soil formation. The DOM concentration and properties along the water flow path through forest ecosystems depend on its sampling location and transformation processes. To improve our understanding of the effects of forest management, especially tree species selection and management intensity, on DOM concentrations and properties of samples from different ecosystem fluxes, we studied throughfall, stemflow, litter leachate and mineral soil solution at 26 forest sites in the three regions of the German Biodiversity Exploratories. We covered forest stands with three management categories (coniferous, deciduous age class and unmanaged beech forests). In water samples from these forests, we monitored DOC concentrations over 4 years and characterized the quality of DOM with UV-vis absorption, fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Additionally, we performed incubation-based biodegradation assays. Multivariate statistics revealed strong significant effects of ecosystem fluxes and smaller effects of main tree species on DOM quality. Coniferous forests differed from deciduous forests by showing larger DOC concentrations, more lignin- and protein-like molecules, and fewer tannin-like molecules in throughfall, stemflow, and litter leachate. Cluster analysis of FT-ICR-MS data indicated that DOM compositions, which varied in aboveground samples depending on tree species, become aligned in mineral soil. This alignment of DOM composition along the water flow path in mineral soil is likely caused by microbial production and consumption of DOM in combination with its interaction with the solid phase, producing a characteristic pattern of organic compounds in forest mineral soils. We found similarly pronounced effects of ecosystem fluxes on the biodegradability of DOM, but surprisingly no differences between deciduous and coniferous forests. Forest management intensity, mainly determined by biomass extraction, contribution of species, which are not site-adapted, and deadwood mass, did not influence DOC concentrations, DOM composition and properties significantly.

scholarly journals Carbon, nitrogen, and phosphorus stoichiometry of organic matter in Swedish forest soils and its relationship with climate, tree species, and soil texture

2021 ◽  
Author(s):  
Marie Spohn ◽  
Johan Stendahl
Keyword(s):  
Organic Matter ◽  
Boreal Forest ◽  
Forest Soils ◽  
Soil Texture ◽  
Tree Species ◽  
Mineral Soil ◽  
Stand Age ◽  
Organic Layer ◽  
Mean Annual Temperature ◽  
P Concentration

Abstract. While the carbon (C) content of temperate and boreal forest soils is relatively well studied, much less is known about the ratios of C, nitrogen (N), and phosphorus (P) of the soil organic matter, and the abiotic and biotic factors that shape them. Therefore, the aim of this study was to explore carbon, nitrogen, and organic phosphorus (OP) contents and element ratios in temperate and boreal forest soils and their relationships with climate, dominant tree species, and soil texture. For this purpose, we studied 309 forest soils with a stand age >60 years located all over Sweden between 56° N and 68° N. The soils are a representative subsample of Swedish forest soils with a stand age >60 years that were sampled for the Swedish Forest Soil Inventory. We found that the N stock of the organic layer increased by a factor of 7.5 from −2 °C to 7.5 °C mean annual temperature (MAT), it increased almost twice as much as the organic layer stock along the MAT gradient. The increase in the N stock went along with an increase in the N : P ratio of the organic layer by a factor of 2.1 from −2 °C to 7.5 °C MAT (R2 = 0.36, p < 0.001). Forests dominated by pine had higher C : N ratios in the litter layer and mineral soil down to a depth of 65 cm than forests dominated by other tree species. Further, also the C : P ratio was increased in the pine-dominated forests compared to forests dominated by other tree species in the organic layer, but the C : OP ratio in the mineral soil was not elevated in pine forests. C, N and OP contents in the mineral soil were higher in fine-textured soils than in coarse-textured soils by a factor of 2.3, 3.5, and 4.6, respectively. Thus, the effect of texture was stronger on OP than on N and C, likely because OP adsorbs very rigidly to mineral surfaces. Further, we found, that the P and K concentrations of the organic layer were inversely related with the organic layer stock. The C and N concentrations of the mineral soil were best predicted by the combination of MAT, texture, and tree species, whereas the OP concentration was best predicted by the combination of MAT, texture and the P concentration of the parent material in the mineral soil. In the organic layer, the P concentration was best predicted by the organic layer stock. Taken together, the results show that the N : P ratio of the organic layer was most strongly related to MAT. Further, the C : N ratio was most strongly related to dominant tree species, even in the mineral subsoil. In contrast, the C : P ratio was only affected by dominant tree species in the organic layer, but the C : OP ratio in the mineral soil was hardly affected by tree species due to the strong effect of soil texture on the OP concentration.

scholarly journals The Effects of Fire on Coarse Woody Debris in Rocky Mountain Coniferous Forests

1995 ◽  
Vol 19 ◽  
pp. 37-38
Author(s):  
Dennis Knight ◽  
Daniel Tinker
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Coarse Woody Debris ◽  
Woody Debris ◽  
Mineral Soil ◽  
Primary Source ◽  
Rocky Mountain ◽  
Timber Harvesting ◽  
Micro Organisms

Primary productivity, the accumulation of nutrients, and other important ecosystem processes are largely dependent on the mineral soil organic matter that has developed during hundreds or thousands of years. In forest ecosystems, the decomposition of coarse woody debris, woody roots, twigs, leaves and micro-organisms is a primary source of this organic matter. Large quantities of coarse woody debris are typically produced following natural disturbances such as fires, pest/pathogen outbreaks, and windstorms, which make a significant contribution to the formation of soil organic matter (SOM). In contrast, timber harvesting often removes most of the coarse woody debris (CWD), which could result in a decrease in the quantity and a change in the quality of mineral soil organic matter.

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