scholarly journals Effects of Surface Soil Removal on Dynamics of Dissolved Inorganic Nitrogen in a Snow-Dominated Forest

2001 ◽  
Vol 1 ◽  
pp. 527-533 ◽  
Author(s):  
M. Ozawa ◽  
H. Shibata ◽  
F. Satoh ◽  
K. Sasa
Keyword(s):  
Soil Solution ◽  
Soil Removal ◽  
Surface Soil ◽  
Water Movement ◽  
Inorganic Nitrogen ◽  
Seasonal Fluctuation ◽  
Early Spring ◽  
Dissolved Inorganic Nitrogen ◽  
And Control ◽  
Treated Site

To clarify the effect of vegetation and surface soil removal on dissolved inorganic nitrogen (N) dynamics in a snow-dominated forest soil in northern Japan, the seasonal fluctuation of N concentrations in soil solution and the annual flux of N in soil were investigated at a treated site (in which surface soil, including understory vegetation and organic and A horizons, was removed) and control sites from July 1998 to June 2000. Nitrate (NO3–) concentration in soil solution at the treated site was significantly higher than that of the control in the no-snow period, and it was decreased by dilution from melting snow. The annual net outputs of NO3–from soil at the treated site and control sites were 257 and –12 mmol m–2year–1, and about 57% of the net output at the treated site occurred during the snowmelt period. NO3–was transported from the upper level to the lower level of soil via water movement during late autumn and winter, and it was retained in soil and leached by melt water in early spring. Removing vegetation and surface soil resulted in an increase in NO3–concentration of soil solution, and snowmelt strongly affected the NO3–leaching from treated soil and the NO3–restoration process in a snow-dominated region.

scholarly journals Dimorphism in cryptophytes—The case of Teleaulax amphioxeia/Plagioselmis prolonga and its ecological implications

2020 ◽  
Vol 6 (37) ◽  
pp. eabb1611 ◽  
Author(s):  
A. Altenburger ◽  
H. E. Blossom ◽  
L. Garcia-Cuetos ◽  
H. H. Jakobsen ◽  
J. Carstensen ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Inorganic Nitrogen ◽  
Early Spring ◽  
Life Cycles ◽  
Sexual Life ◽  
Dissolved Inorganic Nitrogen ◽  
High Genetic Diversity ◽  
Adverse Conditions ◽  
Ecological Implications ◽  
Unicellular Organisms

Growing evidence suggests that sexual reproduction might be common in unicellular organisms, but observations are sparse. Limited knowledge of sexual reproduction constrains understanding of protist ecology. Although Teleaulax amphioxeia and Plagioselmis prolonga are common marine cryptophytes worldwide, and are also important plastid donors for some kleptoplastic ciliates and dinoflagellates, the ecology and development of these protists are poorly known. We demonstrate that P. prolonga is the haploid form of the diploid T. amphioxeia and describe the seasonal dynamics of these two life stages. The diploid T. amphioxeia dominates during periods of high dissolved inorganic nitrogen (DIN) and low irradiance, temperature, and grazing (winter and early spring), whereas the haploid P. prolonga becomes more abundant during the summer, when DIN is low and irradiance, temperature, and grazing are high. Dimorphic sexual life cycles might explain the success of this species by fostering high genetic diversity and enabling endurance in adverse conditions.

Influence of inorganic nitrogen cycling on the δ15N of Lake Ontario biota

2000 ◽  
Vol 57 (7) ◽  
pp. 1489-1496 ◽  
Author(s):  
M F Leggett ◽  
O Johannsson ◽  
R Hesslein ◽  
D G Dixon ◽  
W D Taylor ◽  
...  
Keyword(s):  
Inorganic Nitrogen ◽  
Seasonal Fluctuation ◽  
Lake Ontario ◽  
Individual Species ◽  
Feeding Strategies ◽  
Dissolved Inorganic Nitrogen ◽  
Calanoid Copepods ◽  
Primary Producers ◽  
Size Fractions ◽  
Diacyclops Thomasi

The seasonal variability in the δ15N of biota at the base of the pelagic food chain in Lake Ontario was studied during the period 1995-1997. Strong seasonal patterns were observed in the δ15N of dissolved inorganic nitrogen, different size fractions of particulate organic matter, and zooplankton split into size fractions of 110-210, 210-295, and >295 µm. Similar patterns were reflected in the δ15N of individual species: Diacyclops thomasi, Bosmina longirostris, Daphnia spp., and calanoid copepods. The seasonal fluctuation of primary producers was a function of the nitrogen enrichment of dissolved inorganic nitrogen during photosynthetic uptake and the δ15N of NH4+ and NO3- used by the algae. The large range in δ15N of primary producers suggests that recycling of nitrogen is an important determinant of δ15N at the base of the food web. The δ15N of individual species of zooplankton reflected the known feeding strategies and dietary preferences.

Characteristics of Non-Point Source N Export via Surface Runoff from Sloping Croplands in Northeast China

2011 ◽  
Vol 347-353 ◽  
pp. 2302-2307 ◽  
Author(s):  
Hong Xiang Wang ◽  
Yi Shi ◽  
Jian Ma ◽  
Cai Yan Lu ◽  
Xin Chen
Keyword(s):  
Point Source ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Inorganic Nitrogen ◽  
Rainfall Amount ◽  
Organic N ◽  
Dissolved Inorganic Nitrogen ◽  
Slope Gradient ◽  
N Loss ◽  
Total N

A field experiment was conducted to study the characteristics of non-point source nitrogen (N) in the surface runoff from sloping croplands and the influences of rainfall and cropland slope gradient. The results showed that dissolved total N (DTN) was the major form of N in the runoff, and the proportion occupied by dissolved inorganic nitrogen (DIN) ranged from 45% to 85%. The level of NH4+-N was generally higher than the level of NO3--N, and averaged at 2.50 mg·L-1and 1.07 mg·L-1respectively. DIN was positively correlated with DTN (R2=0.962). Dissolved organic N (DON) presented a moderate seasonal change and averaged at 1.40 mg·L-1. Rainfall amount and rainfall intensity significantly affected the components of DTN in the runoff. With the increase of rainfall amount and rainfall intensity, the concentrations of DTN, NH4+-N and NO3--N presented a decreased trend, while the concentration of DON showed an increased trend. N loss went up with an increase in the gradient of sloping cropland, and was less when the duration was longer from the time of N fertilization.fertilization.

Variation in the instream dissolved inorganic nitrogen response between and within rainstorm events in an urban watershed

2008 ◽  
Vol 43 (11) ◽  
pp. 1223-1233 ◽  
Author(s):  
Bernice R. Rosenzweig ◽  
Hee Sun Moon ◽  
James A. Smith ◽  
Mary Lynn Baeck ◽  
Peter R. Jaffe
Keyword(s):  
Inorganic Nitrogen ◽  
Urban Watershed ◽  
Dissolved Inorganic Nitrogen ◽  
Nitrogen Response

Modelled estimates of dissolved inorganic nitrogen exported to the Great Barrier Reef lagoon

2021 ◽  
Vol 171 ◽  
pp. 112655
Author(s):  
G.L. McCloskey ◽  
R. Baheerathan ◽  
C. Dougall ◽  
R. Ellis ◽  
F.R. Bennett ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Inorganic Nitrogen ◽  
Barrier Reef ◽  
Dissolved Inorganic Nitrogen ◽  
Reef Lagoon

scholarly journals Modelling the ecosystem effects of nitrogen deposition: Model of Ecosystem Retention and Loss of Inorganic Nitrogen (MERLIN

1997 ◽  
Vol 1 (1) ◽  
pp. 137-158 ◽  
Author(s):  
B. J. Cosby ◽  
R. C. Ferrier ◽  
A. Jenkins ◽  
B. A. Emmett ◽  
R. F. Wright ◽  
...  
Keyword(s):  
Nitrogen Deposition ◽  
Soil Solution ◽  
Nitrogen Uptake ◽  
Inorganic Nitrogen ◽  
Balance Model ◽  
Litter Production ◽  
Catchment Scale ◽  
Exchange Constants ◽  
External Sources ◽  
Carbon Productivity

Abstract. A catchment-scale mass-balance model of linked carbon and nitrogen cycling in ecosystems has been developed for simulating leaching losses of inorganic nitrogen. The model (MERLIN) considers linked biotic and abiotic processes affecting the cycling and storage of nitrogen. The model is aggregated in space and time and contains compartments intended to be observable and/or interpretable at the plot or catchment scale. The structure of the model includes the inorganic soil, a plant compartment and two soil organic compartments. Fluxes in and out of the ecosystem and between compartments are regulated by atmospheric deposition, hydrological discharge, plant uptake, litter production, wood production, microbial immobilization, mineralization, nitrification, and denitrification. Nitrogen fluxes are controlled by carbon productivity, the C:N ratios of organic compartments and inorganic nitrogen in soil solution. Inputs required are: 1) temporal sequences of carbon fluxes and pools- 2) time series of hydrological discharge through the soils, 3) historical and current external sources of inorganic nitrogen; 4) current amounts of nitrogen in the plant and soil organic compartments; 5) constants specifying the nitrogen uptake and immobilization characteristics of the plant and soil organic compartments; and 6) soil characteristics such as depth, porosity, bulk density, and anion/cation exchange constants. Outputs include: 1) concentrations and fluxes of NO3 and NH4 in soil solution and runoff; 2) total nitrogen contents of the organic and inorganic compartments; 3) C:N ratios of the aggregated plant and soil organic compartments; and 4) rates of nitrogen uptake and immobilization and nitrogen mineralization. The behaviour of the model is assessed for a combination of land-use change and nitrogen deposition scenarios in a series of speculative simulations. The results of the simulations are in broad agreement with observed and hypothesized behaviour of nitrogen dynamics in growing forests receiving nitrogen deposition.

scholarly journals Forest defoliator outbreaks alter nutrient cycling in northern waters

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Samuel G. Woodman ◽  
Sacha Khoury ◽  
Ronald E. Fournier ◽  
Erik J. S. Emilson ◽  
John M. Gunn ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Water Chemistry ◽  
Inorganic Nitrogen ◽  
Biogeochemical Cycles ◽  
Dissolved Inorganic Nitrogen ◽  
Insect Outbreaks ◽  
Receiving Waters ◽  
North Temperate Lakes ◽  
Lake Waters ◽  
Terrestrial Biomass

AbstractInsect defoliators alter biogeochemical cycles from land into receiving waters by consuming terrestrial biomass and releasing biolabile frass. Here, we related insect outbreaks to water chemistry across 12 boreal lake catchments over 32-years. We report, on average, 27% lower dissolved organic carbon (DOC) and 112% higher dissolved inorganic nitrogen (DIN) concentrations in lake waters when defoliators covered entire catchments and reduced leaf area. DOC reductions reached 32% when deciduous stands dominated. Within-year changes in DOC from insect outbreaks exceeded 86% of between-year trends across a larger dataset of 266 boreal and north temperate lakes from 1990 to 2016. Similarly, within-year increases in DIN from insect outbreaks exceeded local, between-year changes in DIN by 12-times, on average. As insect defoliator outbreaks occur at least every 5 years across a wider 439,661 km2 boreal ecozone of Ontario, we suggest they are an underappreciated driver of biogeochemical cycles in forest catchments of this region.

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