Molybdenum at German Norway spruce sites: contents and mobility

2000 ◽  
Vol 30 (7) ◽  
pp. 1034-1040 ◽  
Author(s):  
Friederike Lang ◽  
Martin Kaupenjohann
Keyword(s):  
Norway Spruce ◽  
Forest Soils ◽  
Forest Floor ◽  
Forest Ecosystems ◽  
Mineral Soil ◽  
Organic Layer ◽  
Soil Profiles ◽  
Nitrogen Turnover ◽  
Acid Forest Soils ◽  
Mineral Soils

Molybdenum plays an important role in the nitrogen turnover of ecosystems. However, very little is known about Mo availability in forest soils. We measured the oxalate-extractable Mo concentrations of acid forest soils, the Mo, nitrate, phosphate, and sulfate fluxes from the organic forest floor into the mineral soil using resin tubes and the Mo concentrations of the tree needles at 28 different Norway spruce (Picea abies (L.) Karst.) sites in southern Germany. The supply of oxalate-extractable Mo varied from 51 to 3400 g·ha-1, with the lowest values occurring in sandstone-derived soils (370 ± 212 g·ha-1; mean ± SD). Molybdenum concentrations of current-year needles were in the range of 5 to 48 ng·g-1. The Mo needle concentrations and oxalate-extractable Mo of soils did not correlate. However, Mo fluxes (6-60 g·ha-1·a-1) from the organic forest floor into the mineral soils were correlated to needle concentrations and to the NO3 fluxes. We conclude that Mo turnover within forest ecosystems is governed by Mo plant availability of mineral soils as well as by plant Mo uptake. In addition, Mo cycling strongly affects Mo distribution within soil profiles and Mo fluxes out of the organic layer.

Prediction of organic carbon content in upland forest soils of Quebec, Canada

2002 ◽  
Vol 32 (5) ◽  
pp. 903-914 ◽  
Author(s):  
Sylvie Tremblay ◽  
Rock Ouimet ◽  
Daniel Houle
Keyword(s):  
Forest Soils ◽  
Forest Floor ◽  
Sustainable Forest Management ◽  
Mineral Soil ◽  
Soil Organic C ◽  
Organic C ◽  
Upland Forest ◽  
Explanatory Variables ◽  
Mineral Soils ◽  
Best Fit

Soil organic carbon (C) is an important component of forest carbon pools and should be taken into account in sustainable forest management. However, there is a need to derive indicators for this attribute, as organic C content (Mg·ha–1) in forest soils is generally not available in Quebec survey data. Thus, we developed models to predict organic C accumulation in the forest floor and in mineral soils of upland forest soils (i.e., with forest floor thickness [Formula: see text]30 cm) using soil survey data as input variables. The best-fit model for predicting forest floor organic C content consisted of the explanatory variables forest floor thickness, latitude, and longitude. The model R2 was 0.76, and its CV was 28%. The second best-fit model, excluding geographical coordinates, included forest floor thickness and mean growing season precipitation as explanatory variables (R2 = 0.71, CV = 29.5%). The model for predicting mineral soil organic C content was composed of two submodels: (i) organic C concentration of a mineral horizon as a function of its colour and (ii) bulk density of that horizon as a function of its estimated C concentration (obtained from the former model). The R2 of the model for predicting organic C content in mineral soils was 0.57, and its CV was 29%. The models were used to predict organic C contents in 5547 pedons, dispersed throughout the commercial forest of Quebec and for which basic soil profile description data were available. It was then possible to evaluate and compare mean soil C accumulation in different forest stand types and to construct two maps of soil organic C accumulation in upland forest soils of southern Quebec. The results pointed out that forest floor thickness combined with mineral soil horizon colour, texture class, and pH would be useful sustainable forest management indicators of organic C accumulation in upland forest soils.

scholarly journals Bioturbation by wild boar increases the stability of forest soil carbon

2019 ◽  
Author(s):  
Axel Don ◽  
Christina Hagen ◽  
Erik Grüneberg ◽  
Cora Vos
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Wild Boar ◽  
Forest Soils ◽  
Forest Floor ◽  
Mineral Soil ◽  
Organic Layer ◽  
Carbon Transfer ◽  
The Stability

Abstract. Most forest soils are characterised by a steep carbon gradient from the forest floor to the mineral soil, indicating that carbon is prevented from entry into the soil. Bioturbation can help incorporate litter-derived carbon into the mineral soil. Wild boar are effective at mixing and grubbing in the soil and wild boar populations are increasing in many parts of the world. In a six-year field study, we investigated the effect of wild boar bioturbation on the stocks and stability of soil organic carbon in two forest areas. Regular bioturbation mimicking grubbing by wild boar was performed artificially in 23 plots and the organic layer and mineral soil down to 15 cm depth were then sampled. No significant changes in soil organic carbon stocks were detected in the bioturbation plots compared with non-disturbed reference plots. However, around 50 % of forest floor carbon was transferred with bioturbation to mineral soil carbon and the stock of stabilised mineral-associated carbon increased by 28 %. Thus, a large proportion of the labile carbon in the forest floor was transformed into more stable carbon. Carbon saturation of mineral surfaces was not detected, but carbon loading per unit mineral surface increased by on average 66 % in the forest floor due to bioturbation. This indicates that mineral forest soils have non-used capacity to stabilise and store carbon. Transfer of aboveground litter into the mineral soil is the only rate-limiting process. Wild boar can help to speed up this process with their grubbing activity.

scholarly journals Simulated wild boar bioturbation increases the stability of forest soil carbon

2019 ◽  
Vol 16 (21) ◽  
pp. 4145-4155 ◽  
Author(s):  
Axel Don ◽  
Christina Hagen ◽  
Erik Grüneberg ◽  
Cora Vos
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Wild Boar ◽  
Forest Soils ◽  
Forest Floor ◽  
Mineral Soil ◽  
Organic Layer ◽  
Carbon Transfer ◽  
The Stability

Abstract. Most forest soils are characterised by a steep carbon gradient from the forest floor to the mineral soil, indicating that carbon is prevented from entry into the soil. Bioturbation can facilitate the incorporation of litter-derived carbon into the mineral soil. Wild boar are effective at mixing and grubbing in the soil and wild boar populations are increasing in many parts of the world. In a 6-year field study, we investigated the effect of simulated wild boar bioturbation on the stocks and stability of soil organic carbon in two forest areas. Regular bioturbation mimicking grubbing by wild boar was performed artificially in 23 plots, and the organic layer and mineral soil down to 15 cm depth were then sampled. No significant changes in soil organic carbon stocks were detected in the bioturbation plots compared with non-disturbed reference plots. However, around 50 % of forest floor carbon was transferred with bioturbation to mineral soil carbon, and the stock of stabilised mineral-associated carbon increased by 28 %. Thus, a large proportion of the labile carbon in the forest floor was transformed into more stable carbon. Carbon saturation of mineral surfaces was not detected, but carbon loading per unit mineral surface increased by on average 66 % in the forest floor due to bioturbation. This indicates that mineral forest soils have non-used capacity to stabilise and store carbon. Transfer of aboveground litter into the mineral soil is the only rate-limiting process. Wild boar may speed up this process with their grubbing activity.

scholarly journals Effects of land use change from natural forest to plantation on C, N and natural abundance of 13C and 15N along a climate gradient in eastern China

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mbezele Junior Yannick Ngaba ◽  
Ya-Lin Hu ◽  
Roland Bol ◽  
Xiang-Qing Ma ◽  
Shao-Fei Jin ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Forest Floor ◽  
Eastern China ◽  
Mineral Soil ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Natural Forests ◽  
Soil C ◽  
Mineral Soils

Abstract Soil C and N turnover rates and contents are strongly influenced by climates (e.g., mean annual temperature MAT, and mean annual precipitation MAP) as well as human activities. However, the effects of converting natural forests to intensively human-managed plantations on soil carbon (C), nitrogen (N) dynamics across various climatic zones are not well known. In this study, we evaluated C, N pool and natural abundances of δ13C and δ15N in forest floor layer and 1-meter depth mineral soils under natural forests (NF) and plantation forest (PF) at six sites in eastern China. Our results showed that forest floor had higher C contents and lower N contents in PF compared to NF, resulting in high forest floor C/N ratios and a decrease in the quality of organic materials in forest floor under plantations. In general, soil C, N contents and their isotope changed significantly in the forest floor and mineral soil after land use change (LUC). Soil δ13C was significantly enriched in forest floor after LUC while both δ13C and δ15N values were enriched in mineral soils. Linear and non-linear regressions were observed for MAP and MAT in soil C/N ratios and soil δ13C, in their changes with NF conversion to PF while soil δ15N values were positively correlated with MAT. Our findings implied that LUC alters soil C turnover and contents and MAP drive soil δ13C dynamic.

scholarly journals Thinning and Burning Effects on Long-Term Litter Accumulation and Function in Young Ponderosa Pine Forests

2020 ◽  
Vol 66 (6) ◽  
pp. 761-769
Author(s):  
Matt Busse ◽  
Ross Gerrard
Keyword(s):  
Ponderosa Pine ◽  
Forest Floor ◽  
Prescribed Burning ◽  
Mineral Soil ◽  
Pine Forests ◽  
Organic Layer ◽  
Litter Accumulation ◽  
Ponderosa Pine Forests ◽  
Essential Components

Abstract We measured forest-floor accumulation in ponderosa pine forests of central Oregon and asked whether selected ecological functions of the organic layer were altered by thinning and repeated burning. Experimental treatments included three thinning methods applied in 1989 (stem only, whole tree, no thin—control) in factorial combination with prescribed burning (spring 1991 and repeated in 2002; no burn—control). Forest-floor depth and mass were measured every 4–6 years from 1991 to 2015. Without fire, there was little temporal change in depth or mass for thinned (270 trees ha−1) and control (560–615 trees ha−1) treatments, indicating balanced litterfall and decay rates across these stand densities. Each burn consumed 50–70 percent of the forest floor, yet unlike thinning, postfire accumulation rates were fairly rapid, with forest-floor depth matching preburn levels within 15–20 years. Few differences in forest-floor function (litter decay, carbon storage, physical barrier restricting plant emergence, erosion protection) resulted from thinning or burning after 25 years. An exception was the loss of approximately 300 kg N ha−1 because of repeated burning, or approximately 13 percent of the total site N. This study documents long-term forest-floor development and suggests that common silvicultural practices pose few risks to organic layer functions in these forests. Study Implications: Mechanical thinning and prescribed fire are among the most widespread management practices used to restore forests in the western US to healthy, firewise conditions. We evaluated their effects on the long-term development of litter and duff layers, which serve dual roles as essential components of soil health and as fuel for potential wildfire. Our study showed that thinning and burning provided effective fuel reduction and resulted in no adverse effects to soil quality in dry ponderosa pine forests of central Oregon. Repeated burning reduced the site carbon and nitrogen pools approximately 9–13 percent, which is small compared to C located in tree biomass and N in mineral soil. Litter accumulation after burning was rapid, and we recommend burning on at least a 15–20-year cycle to limit its build-up.

Equilibrium and kinetic approaches for modelling sorption processes on radiocesium soil profiles in Fukushima prefecture

2020 ◽  
Author(s):  
Hamza Chaif ◽  
Frederic Coppin ◽  
Aya Bahi ◽  
Laurent Garcia-Sanchez
Keyword(s):  
Soil Contamination ◽  
Residence Time ◽  
Nuclear Power ◽  
Mineral Soil ◽  
Soil Surface ◽  
Organic Soils ◽  
Organic Layer ◽  
Soil Profiles ◽  
Sorption Model ◽  
Slow Evolution

<p>The study of radionuclides (RNs) retention processes onto the solid phases is a key element for the prediction of their transfer in soils. It allows a better quantification of the persistence of radioactive contaminants on the soil surface, their availability for root uptake and their vertical transfer towards groundwater.</p><p>This work addresses the comparison between equilibrium and kinetic hypotheses of sorption processes on real post-accidental soil contamination profiles. The equilibrium-kinetic (EK) sorption model was selected as a non-equilibrium parameterization embedding the K<sub>d</sub> approach. It supposes the existence of two types of sorption sites. The first sites are at equilibrium with solution, whereas for the second sites, kinetics of the sorption and desorption are taken into consideration.</p><p>We focused our study on four <sup>137</sup>Cs soil contamination profiles measured in a cedar stand 35 km northwest of the Fukushima Dai-ichi Nuclear Power Plant. Profiles were sampled at four different dates (between 2013 and 2018) by measuring <sup>137</sup>Cs activity in both organic (humus + litter layer) and mineral soil layers reaching a maximum depth of 20cm.</p><p>To successfully simulate the <sup>137</sup>Cs transfer throughout these soil profiles, the input flux at the mineral soil surface was reconstructed from monitored throughfall, stemflow and litterfall fluxes in the same forest stand from July 2011 to November 2016 crossed with initial deposit and dynamic of the organic layer activity.</p><p>The EK model reproduced the measured contamination profiles slightly better than the fitted K<sub>d</sub> model. While both models were able to reproduce the overall vertical distribution throughout the profiles, the persistent contamination at the surface was closer to the measured value with the EK approach. Additionally, the fitted K<sub>d</sub> parameters (2000 L/kg to 6500 L/kg depending on the parcel) were considerably higher than the recommended value by The IAEA for organic soils (270 L/kg). When used, this recommended K<sub>d</sub> value produced profiles with considerably faster transfer rate between layers and shorter persistence of the contamination at the surface.</p><p>To further distinguish the models behaviors, long term simulations were conducted. EK hypotheses induced much longer residence time of the contamination at the soil surface. For instance, by 2030, the EK approach predicted that 75 % of the contamination still remained in the 0-2 cm layer due to the slow desorption rate, whereas the K<sub>d</sub> approach predicted it to be around 51 %. This fraction becomes even smaller (8 %) when using the K<sub>d</sub> value (270 L/kg) recommended by the IAEA for organic soils.</p><p>These results prove that the choice of the sorption model is critical in post-accidental situations. An equilibrium approach, especially when using recommended parameter values, can result in an underestimation of the RNs residence time in the surface. Whereas a kinetic approach, by distinguishing different sorption and desorption rates, is able to reproduce the slow evolution of <sup>137</sup>Cs soil profiles with time that is already observed in the case of Chernobyl contaminated areas 30 years after the accident.</p>

scholarly journals Natural abundance of 15N of a spruce forest ecosystem under acid rain and manipulated clean rain field conditions

2008 ◽  
Vol 54 (No. 8) ◽  
pp. 377-387
Author(s):  
P. Sah S ◽  
R. Brumme ◽  
N. Lamersdorf
Keyword(s):  
Forest Floor ◽  
Forest Ecosystems ◽  
Soil Depth ◽  
Mineral Soil ◽  
Control Plot ◽  
Natural Abundance ◽  
Spruce Forest ◽  
Litter Fall ◽  
Bulk Precipitation ◽  
N Status

We analysed stable isotopes of N in a spruce forest under ambient rainfall (no further manipulation of the atmospheric input) and clean rain application (10 years of reduced inorganic N- and acid-constituent input). The objectives of the study were to assess whether or not the natural <sup>15</sup>N abundance would function as an indicator for the N-status of our forest ecosystems. For this purpose, natural <sup>15</sup>N abundance values were measured in needles, litter fall, roots, soil, bulk precipitation, throughfall and soil water of both plots. In the bulk precipitation and throughfall the &delta;<sup>15</sup>N values of NO<sub>3</sub>-N were in the range reported by other studies (–16 to + 23‰). In both plots, the throughfall was greatly depleted of <sup>15</sup>N compared to the bulk precipitation and this was attributed to nitrification in the canopy leaves, leading to &delta;<sup>15</sup>N-depleted nitrate production in the leaves that leaches down the soil surface. Nitrate in seepage water showed a general increase in &delta;<sup>15</sup>N values when it passes through the upper mineral soil (10 cm soil depth) and infiltrates into deeper mineral soil horizons (100 cm soil depth), similar to the &delta;<sup>15</sup>N enrichment of total nitrogen in the mineral soil. We observed <sup>15</sup>N depletion in both green needles and litter fall at the clean rain plot, compared to the N-saturated control plot. We assumed it to be due to increased mycorrhizal N-uptake under N limited, i.e. clean rain conditions which are indicated by relatively lower N concentrations of green needles. With respect to the vertical gradient of the <sup>15</sup>N abundance in the forest floor, both plots differ from each other, showing an untypical peak of &delta;<sup>15</sup>N depletion in the humus layer, which is more pronounced at the control plot. In contrast to the mineral soil where mineralisation is a dominant process for fractionation we attribute the &delta;<sup>15</sup>N pattern in the forest floor to additional processes like litter input and immobilisation. We conclude that the &delta;<sup>15</sup>N natural abundance analysis is helpful for interpreting the N-status of forest ecosystems but further research is needed especially with respect to the soil-root interface.

Distribution of water-soluble organic carbon in an aspen forest soil

1996 ◽  
Vol 26 (7) ◽  
pp. 1266-1272 ◽  
Author(s):  
W.Z. Huang ◽  
J.J. Schoenau
Keyword(s):  
Forest Floor ◽  
Mineral Soil ◽  
Water Soluble ◽  
Organic Layer ◽  
Litter Fall ◽  
Organic C ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Prince Albert National Park ◽  
Aspen Forest

The purpose of this study was to characterize the quantity, distribution, and variance of water-soluble organic C (WSOC) in a soil under trembling aspen (Populustremuloides Michx.) in the southern boreal forest of Canada. WSOC was determined monthly from May to October 1994 in the forest floor horizons (L, F, H) and mineral soil (Ae) of an aspen stand in Prince Albert National Park, Saskatchewan. The concentration of WSOC varied considerably with profile depth, but varied little among the slope positions and aspects. The L horizon had the highest WSOC concentration (425–8690 mg•kg−1 ovendried soil), followed by the F, H, and Ae horizons. The concentration of WSOC in the Ae horizon was significantly related to the concentration in forest floor horizons above. Water-soluble organic C in the Ae horizon likely was derived from the overlying organic layer by leaching. In a laboratory incubation, the rate of WSOC release (the net result of release and uptake) during incubation decreased continuously over time, but in the field, the rate of WSOC release decreased slightly early in the growing season, but increased later in the season as new litter fall reached the forest floor. This indicates that litter fall is a major factor in the replenishment of WSOC in aspen forest stands.

Denitrification and nitrogen fixation in floodplain successional soils along the Tanana River, interior Alaska

1993 ◽  
Vol 23 (5) ◽  
pp. 956-963 ◽  
Author(s):  
K.M. Klingensmith ◽  
K. Van Cleve
Keyword(s):  
Nitrogen Fixation ◽  
Forest Floor ◽  
Nitrogenase Activity ◽  
Mineral Soil ◽  
White Spruce ◽  
Interactive Effects ◽  
Successional Stage ◽  
Alder Forest ◽  
Mineral Soils ◽  
Soil Interface

Forest floors and mineral soils from early (open willow), middle (poplar–alder), and late (white spruce) floodplain primary successional stages were examined for nitrogen fixation and denitrification. The acetylene-reduction and acetylene-inhibition techniques were used separately and in combination to measure nitrogenase and denitrification activities, both in laboratory and field studies. In situ N2O production was undetectable at all sites and during all sampling periods. Denitrifying activity measured in the field with acetylene amendments was low to undetectable, except after a brief flood in the open willow stand when N2O production ranged from undetectable to 34 ng N•cm−2•h−1 within the newly deposited alluvium–old mineral soil interface. Intact core assays also had low to undetectable denitrification activities; the highest activities (259 ng N•g−1 h−1) were measured in the poplar–alder forest floor in the fall. Laboratory studies showed that potential denitrification enzyme activity (DEA) was also greatest in the poplar–alder forest floor (4332 ng N•g−1•h−1), once again occurring in the fall. In early and midsuccessional stages, the interactive effects of temperature, carbon, and NO3− limited denitrification, yet even with the addition of the limiting amendments, low to undetectable DEA was observed in mineral soils. The later white spruce successional stage also had low to undetectable DEA, increasing only with the addition of the full DEA media and independent of temperature changes. Nonsymbiotic nitrogenase activities were highly variable, ranging from undetectable to 30 ng N•cm−2•h−1. Highest activities were seen in the open willow, newly deposited alluvium–old mineral soil interface immediately after a flood and approximately 1 month after the flood on the newly deposited silt surface. Only the white spruce forest floor had measurable nonsymbiotic nitrogenase activity at all sampling times. Alder root nodule nitrogenase activity showed no significant differences between sampling periods. The estimated annual nitrogen fixation rate of 164 kg N•ha−1 for alder root nodules is a substantial N contribution to the alder stand and to the floodplain ecosystem in general.

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