scholarly journals Wildfire effects on ecosystem nitrogen cycling in a Chinese boreal larch forest, revealed by <sup>15</sup>N natural abundance

2016 ◽  
Author(s):  
Weili Liu ◽  
Lin Qi ◽  
Yunting Fang ◽  
Jian Yang
Keyword(s):  
Nitrogen Cycling ◽  
Mineral Soil ◽  
Organic Soil ◽  
N Cycling ◽  
Natural Abundance ◽  
Burned Area ◽  
Inorganic N ◽  
Legacy Effect ◽  
Net Mineralization ◽  
Transformation Rates

Abstract. Wildfire is reported to exert strong influences on N cycling, particularly during the early succession period immediately after burning (i.e., < 1 year). Previous studies have mainly focused on wildfires influences on inorganic N concentrations and N mineralization rates; but plant and soil 15N natural abundance (expressed by δ15N), as a spatial-temporal integrator of ecosystem N cycling, could provide a more comprehensive understanding of wildfire on various N cycling processes at a relatively broader time scale. In this study, we attempted to evaluate legacy effects of wildfire on nitrogen cycling using δ15N in a boreal forest of northeastern China, which is an important yet understudied ecosystem. We measured inorganic N concentrations (NH4+ and NO3−) and net N transformation rates (net ammonification, net nitrification, and net mineralization) of organic and mineral soil 4 years after a wildfire and compared with unburned area. We also measured δ15N of plant and soil samples in 4 and 5 years after the fire. We found that even 4 years after burning, wildfire still increased net mineralization and net ammonification in the organic soil and increased NH4+ and total inorganic N (TIN) concentrations in the mineral soil. Organic soil and foliar δ15N were significantly higher (by 2.2 ‰ and 7.4 ‰, respectively) in the burned area than the unburned area. Five years after fire, plant tissues such as foliar, branch, fine roots and moss in the burned area were increased significantly (by 1.7 ‰ to 6.4 ‰) greater than that in unburned area. The wildfire also significantly increased the δ15N of Oi, Oa+e and 0–10 cm mineral soil, but had no significant effects on deeper layer of mineral soil. These results indicate the wildfire had a strong legacy effect on N cycling. We suggest that the change of abiotic environment was the primary mechanism determining inorganic nitrogen transformation rates, and the NH3 volatilization might play a key role in severe N losses and thereby affect soil and plant 15N in this ecosystem.

scholarly journals Long-term elevation of temperature affects organic N turnover and associated N2O emissions in a permanent grassland soil

2016 ◽  
Author(s):  
Anne B. Jansen-Willems ◽  
Gary J. Lanigan ◽  
Timothy J. Clough ◽  
Louise C. Andresen ◽  
Christoph Müller
Keyword(s):  
Organic N ◽  
N2o Emissions ◽  
Inorganic N ◽  
Soil Warming ◽  
N Transformations ◽  
Permanent Grassland ◽  
N Transformation ◽  
Legacy Effect ◽  
Transformation Rates

Abstract. Over the last century an increase in mean soil surface temperature has been observed and it is predicted to increase further in the future. To evaluate the legacy effects of increased temperature on both nitrogen (N) transformation rates in the soil and nitrous oxide (N2O) emissions, an incubation experiment was conducted with soils taken from a long term in situ warming experiment on temperate permanent grassland. In this experiment the soil temperature was elevated by 0 (control), 1, 2 or 3 °C (4 replicates per treatment) using IR-lamps over a period of 6 years. The soil was subsequently incubated under common conditions (20 °C and 50 % humidity) and labelled with NO315NH4 Gly, 15NO3NH4 Gly or NO3NH4 15N-Gly. Both inorganic N (NO3−NH4+) and NO32− contents were higher in soil subjected to the +2 and +3 °C temperature elevations. Analyses of N transformations using a 15N tracing model, showed that, following incubation, gross organic (and not inorganic) N transformation rates decreased in response to the prior soil warming treatment. This was also reflected in reduced N2O emissions associated with organic N oxidation and denitrification. A newly developed source partitioning model showed the importance of oxidation of organic N as a source of N2O. Concluding, long term soil warming can cause a legacy effect which diminishes organic N turn over and the release of N2O from organic N and denitrification.

scholarly journals Dynamic of nitrogen and dissolved organic carbon in an alpine forested catchment: atmospheric deposition and soil solution trends

2019 ◽  
Vol 34 ◽  
pp. 41-66 ◽  
Author(s):  
Raffaella Balestrini ◽  
Carlo Andrea Delconte ◽  
Andrea Buffagni ◽  
Alessio Fumagalli ◽  
Michele Freppaz ◽  
...  
Keyword(s):  
Soil Solution ◽  
Forest Ecosystem ◽  
Forest Floor ◽  
Mineral Soil ◽  
Chemical Species ◽  
Organic N ◽  
Seasonal Temperature ◽  
Inorganic N ◽  
Forest Floor Leachates ◽  
Throughfall Deposition

A number of studies have reported decreasing trends of acidifying and N deposition inputs to forest areas throughout Europe and the USA in recent decades. There is a need to assess the responses of the ecosystem to declining atmospheric pollution by monitoring the variations of chemical species in the various compartments of the forest ecosystem on a long temporal scale. In this study, we report on patterns and trends in throughfall deposition concentrations of inorganic N, dissolved organic N (DON) and C (DOC) over a 20-year (1995–2015) period in the LTER site -Val Masino (1190 m a.s.l.), a spruce forest, in the Central Italian Alps. The same chemical species were studied in the litter floor leachates and mineral soil solution, at three different depths (15, 40 and 70 cm), over a 10-year period (2005–2015). Inorganic N concentration was drastically reduced as throughfall and litter floor leachates percolated through the topsoil, where the measured mean values (2 µeq L-1) were much lower than the critical limits established for coniferous stands (14 µeq L-1). The seasonal temperature dependence of throughfall DOC and DON concentration suggests that the microbial community living on the needles was the main source of dissolved organic matter. Most of DOC and DON infiltrating from the litter floor were retained in the mineral soil. The rainfall amount was the only climatic factor exerting a control on DOC and N compounds in throughfall and forest floor leachates over a decadal period. Concentration of SO4 and NO3 declined by 50% and 26% respectively in throughfall deposition. Trends of NO3 and SO4 in forest floor leachates and mineral soil solution mirrored declining depositions. No trends in both DON and DOC concentration and in DOC/DON ratio in soil solutions were observed. These outcomes suggest that the declining NO3 and SO4 atmospheric inputs did not influence the dynamic of DON and DOC in the Val Masino forest. The results of this study are particularly relevant, as they are based on a comprehensive survey of all the main compartments of the forest ecosystem. Moreover, this kind of long-term research has rarely been carried out in the Alpine region.

scholarly journals Effects of Brash Removal After Clear Felling on Soil and Soil-Solution Chemistry and Field-Layer Biomass in an Experimental Nitrogen Gradient

2001 ◽  
Vol 1 ◽  
pp. 457-466 ◽  
Author(s):  
E. Ring ◽  
L. Hogbom ◽  
H.A. Nohrstedt
Keyword(s):  
Soil Solution ◽  
Alternative Energy ◽  
Mineral Soil ◽  
Solution Chemistry ◽  
Soil Solution Chemistry ◽  
Inorganic N ◽  
Field Layer ◽  
Humus Layer ◽  
Irregular Pattern ◽  
N Dose

Biofuels, such as brash from forest fellings, have been proposed as an alternative energy source. Brash removal may affect the sustainability of forest production, e.g., through a change in the availability of cations and N in the soil. We report initial effects of brash removal on inorganic N content in humus and mineral soil, soil-solution chemistry, and field-layer biomass after clear felling an N-fertilisation experiment in central Sweden. The experiment comprised six different fertiliser levels, ranging from 0 to 600 kg N ha�1. Urea was given every 5th year during 1967 to 1982 to replicated plots, giving total doses of 0 to 2400 kg N ha�1. Clear felling took place in 1995, 13 years after the last fertilisation. The removal of brash decreased the NO3� content in the humus layer after clear felling. A decrease in the NO3� concentration of the soil solution was indicated during most of the study period as well. No effect of the previous N fertilisation was found in the humus layer, but in the mineral soil there was an increase in NO3� content for the highest N dose after clear felling (p = 0.06). The soil-solution chemistry and the field-layer biomass showed an irregular pattern with no consistent effects of brash removal or previous fertilisation.

scholarly journals The Diversity of Nitrogen-Cycling Microbial Genes in a Waste Stabilization Pond Reveals Changes over Space and Time that Is Uncoupled to Changing Nitrogen Chemistry

2020 ◽  
Author(s):  
A. Rose ◽  
A. Padovan ◽  
K. Christian ◽  
J. van de Kamp ◽  
M. Kaestli ◽  
...  
Keyword(s):  
Nitrogen Cycling ◽  
Functional Groups ◽  
Nitrogen Removal ◽  
Ammonia Oxidation ◽  
Gene Array ◽  
N Cycling ◽  
Nitrogen Levels ◽  
Space And Time ◽  
Waste Stabilization ◽  
Wastewater Samples

Abstract Nitrogen removal is an important process for wastewater ponds prior to effluent release. Bacteria and archaea can drive nitrogen removal if they possess the genes required to metabolize nitrogen. In the tropical savanna of northern Australia, we identified the previously unresolved microbial communities responsible for nitrogen cycling in a multi-pond wastewater stabilization system by measuring genomic DNA and cDNA for the following: nifH (nitrogen fixation); nosZ (denitrification); hzsA (anammox); archaeal AamoA and bacterial BamoA (ammonia oxidation); nxrB (nitrite oxidation); and nrfA (dissimilatory NO3 reduction to NH3). By collecting 160 DNA and 40 cDNA wastewater samples and measuring nitrogen (N)-cycling genes using a functional gene array, we found that genes from all steps of the N cycle were present and, except for nxrB, were also expressed. As expected, N-cycling communities showed daily, seasonal, and yearly shifts. However, contrary to our prediction, probes from most functional groups, excluding nosZ and AamoA, were different between ponds. Further, different genes that perform the same N-cycling role sometimes had different trends over space and time, resulting in only weak correlations between the different functional communities. Although N-cycling communities were correlated with wastewater nitrogen levels and physico-chemistry, the relationship was not strong enough to reliably predict the presence or diversity of N-cycling microbes. The complex and dynamic response of these genes to other functional groups and the changing physico-chemical environment provides insight into why altering wastewater pond conditions can result an abundance of some gene variants while others are lost.

Atrazine in mineral soil: chemical species and catalysed hydrolysis

1992 ◽  
Vol 70 (6) ◽  
pp. 1597-1603 ◽  
Author(s):  
Donald S. Gamble ◽  
Shahamat U. Khan
Keyword(s):  
Mineral Soil ◽  
Chemical Species ◽  
Organic Soil ◽  
Kinetics Parameters ◽  
Equilibrium Function ◽  
Data Scatter ◽  
Acidic Sites ◽  
Equilibrium And Kinetics ◽  
Relationship Of ◽  
The Relationship

Equilibrium and kinetics parameters have been evaluated at 25.0 °C for the heterogeneous catalysis of atrazine hydrolysis in slurries of a chemically characterized mineral soil. The fraction of acidic sites that accounts for sorption capacity, and the sorption equilibrium function resemble those for humic acid and organic soil. Sorption and desorption half-lives increased with increasing coverage of sorption sites. The sorption half-lives ranged from 3.6 to 735 days. The desorption half-lives ranged from 1 to 11 days. The hydrolysis half-lives ranged from 9.6 to 168 days and are consistent with Brönsted acid catalysis theory. The relationship of independent variables to data scatter has been analyzed. The information obtained should be useful for water and solute transport models.

Viable seed populations by soil depth and potential site recolonization after disturbance

1977 ◽  
Vol 55 (18) ◽  
pp. 2408-2412 ◽  
Author(s):  
Janice M. Moore ◽  
Ross W. Wein
Keyword(s):  
Soil Depth ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Organic Soil ◽  
Viable Seed ◽  
Soil Layers ◽  
Forest Experiment Station ◽  
Viable Seeds ◽  
Study Sites ◽  
Germination Experiment

Seedling emergence from organic and mineral soil layers was measured for nine study sites at the Acadia Forest Experiment Station near Fredericton, New Brunswick. The number of viable seeds showed a decrease from deciduous-dominated forest, to conifer-dominated forest, to organic soil study sites. Viable seed number varied from 3400/m2 for a deciduous-dominated forest study site to zero for a bog study site. Most seeds germinated from the upper organic soil layers of all study sites and were predominantly Rubus strigosus Michx. After the germination experiment, ungerminated seeds, which showed no viability by the tetrazolium test, were separated from the soil. These seeds were almost entirely Betula spp. and seed numbers were as high as 4200–9400/m2 for a deciduous-dominated forest. The applicability of the results to differing types of postdisturbance revegetation is discussed.

Hypholoma lateritiumisolated from coarse woody debris, the forest floor, and mineral soil in a deciduous forest in New Hampshire

Botany ◽  
2012 ◽  
Vol 90 (6) ◽  
pp. 457-464 ◽  
Author(s):  
Therese A. Thompson ◽  
R. Greg Thorn ◽  
Kevin T. Smith
Keyword(s):  
New Hampshire ◽  
Deciduous Forest ◽  
Repetitive Sequences ◽  
Mineral Soil ◽  
Acer Rubrum ◽  
Organic Soil ◽  
Nuclear Ribosomal Dna ◽  
Soil Horizon ◽  
Soil Horizons ◽  
Internal Transcribed Spacer Region

Fungi in the Agaricomycetes (Basidiomycota) are the primary decomposers in temperate forests of dead wood on and in the forest soil. Through the use of isolation techniques selective for saprotrophic Agaricomycetes, a variety of wood decay fungi were isolated from a northern hardwood stand in the Bartlett Experimental Forest, New Hampshire, USA. In particular, Hypholoma lateritium (Schaeff.: Fr.) P. Kumm. was isolated from basidiocarps, decaying Acer rubrum L. logs, the Oe organic soil horizon, and the E and BC mineral soil horizons. Identification was confirmed by sequence analysis of the internal transcribed spacer region of nuclear ribosomal DNA. All isolates had identical sequences in this region to previously published sequences for the species; some were monokaryotic and simple-septate and others were dikaryotic, with clamp connections. Isolates were further characterized by banding patterns (DNA fingerprints) produced with PCR primers based in simple repetitive sequences and the minisatellite M13. Nine dikaryotic isolates from basidiocarps and from soil horizons Oe, E, and BC had identical fingerprint patterns with all primers tested. The confirmed presence of H. lateritium suggests that this fungus could form a mycelial translocation network that bridges mineral and organic soil horizons and decaying logs.

Development of calibration algorithms for selected water content reflectometry probes for burned and non-burned organic soils of Alaska

2010 ◽  
Vol 19 (7) ◽  
pp. 961 ◽  
Author(s):  
Laura L. Bourgeau-Chavez ◽  
Gordon C. Garwood ◽  
Kevin Riordan ◽  
Benjamin W. Koziol ◽  
James Slawski
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Soil Profile ◽  
Soil Moisture Content ◽  
Mineral Soil ◽  
Organic Soil ◽  
Organic Content ◽  
Organic Soils ◽  
Probe Type

Water content reflectometry is a method used by many commercial manufacturers of affordable sensors to electronically estimate soil moisture content. Field‐deployable and handheld water content reflectometry probes were used in a variety of organic soil‐profile types in Alaska. These probes were calibrated using 65 organic soil samples harvested from these burned and unburned, primarily moss‐dominated sites in the boreal forest. Probe output was compared with gravimetrically measured volumetric moisture content, to produce calibration algorithms for surface‐down‐inserted handheld probes in specific soil‐profile types, as well as field‐deployable horizontally inserted probes in specific organic soil horizons. General organic algorithms for each probe type were also developed. Calibrations are statistically compared to determine their suitability. The resulting calibrations showed good agreement with in situ validation and varied from the default mineral‐soil‐based calibrations by 20% or more. These results are of particular interest to researchers measuring soil moisture content with water content reflectometry probes in soils with high organic content.

Roles of clay layers in rainfall-runoff processes in a serpentinite headwater catchment

2020 ◽  
Author(s):  
Takahiko Yoshino ◽  
Shin'ya Katsura
Keyword(s):  
Water Flow ◽  
Groundwater Level ◽  
Mineral Soil ◽  
High Water ◽  
Organic Soil ◽  
Rainfall Runoff ◽  
Soil Layers ◽  
Clay Layers ◽  
Headwater Catchment

&lt;p&gt;Rainfall-runoff processes in a headwater catchment have been typically explained by water flow in permeable soil layers (comprised of organic soil layers and mineral soil layers produced by weathering of bedrock) overlying less permeable layers (i.e., bedrock). In a catchment where mineral soils are characterized by clayey materials (e.g., mudstone, slate, and serpentine catchment), it is possible that mineral soil layers function substantially as less permeable layers because of a low permeability of clayey materials. However, roles of clay layers in rainfall-runoff processes in such a headwater catchment are not fully understood. In this study, we conducted detailed hydrological, hydrochemical, and thermal observations in a serpentinite headwater catchment (2.12 ha) in Hokkaido, Northern Japan, where mineral soil layers consisting of thick clay layers (thickness: approximately 1.5 m) produced by weathering of the serpentinite bedrock underlies organic soil layers (thickness: approximately 0.4 m). Saturated hydraulic conductivity (Ks) and water retention curve of these two layers were also measured in a laboratory. The observation results demonstrated that groundwater was formed perennially in the organic soil layers and clay layers. The groundwater level within the organic soil layers and specific discharge of the catchment showed rapid and flashy change in response to rainfall. In contrast, the groundwater level within the clay layers showed slow and small change. Temperature of the groundwater and stream water suggested that water from the depth of the organic soil layers contributed to streamflow. The electric conductivity (EC) of the groundwater in the clay layers was very high, ranging from 321 to 380 &amp;#181;S cm&amp;#713;&amp;#185;. On the other hand, the EC of soil water (unsaturated water stored in the organic soil layers) was relatively low, ranging from 98 to 214 &amp;#181;S cm&amp;#713;&amp;#185;. Hydrograph separation using EC showed that contribution of water emerging from the clay layers to the total streamflow ranged from 31 to 76% in low to high flow periods. Temporal variation in the total head, measured using tensiometers installed at four depths at the ridge of the catchment, indicated that in wet periods when the groundwater level in the organic soil layers was high, water flow from the organic soil layers to the clay layers occurred, whereas, in dry periods, water flow from the clay layers into the organic soil layers occurred. The laboratory measurements showed that the organic soil layers had high Ks (10&amp;#713;&amp;#178; cm s&amp;#713;&amp;#185;) and low water-holding capacity, whereas the clay layers had low Ks (10&amp;#713;&amp;#8308; cm s&amp;#713;&amp;#185;) and high water-holding capacity. It can be concluded from these results that clay layers play two roles: (1) forming perched groundwater table and lateral flow on the clay layers (the role of less permeable layers) and (2) supplying water into the organic soil layers in the dry periods (the role of water supplier).&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document