Feedback from soil inorganic nitrogen on soil organic matter mineralisation and growth in a boreal forest ecosystem

There is a growing body of evidence that plants uptake a monumental amount of organic forms of nitrogen (N) like amino acids in addition to those in inorganic forms. An amino acid-based fertiliser has been shown to improve seedling development and commercialised. Boreal forests store a substantial amount of carbon (C) in the soil and this is widely known to be further enhanced by the addition of inorganic nitrogen fertiliser via hampered decomposition. However, very little is known about how amino acid-based fertiliser influences C/N cycling in the boreal soils. The organic forms of N supply not only nitrogen but also carbon. If the previously demonstrated suppression of SOM decomposition is owing to altered C:N ratios in substrates, the amino acid-based fertiliser may not have as pronounced effects on the soil as the inorganic fertiliser.&#160;&#160;We have examined the impacts of the organic fertiliser (100 kg N and 130 kg C ha-1 year-1)&#8212;arginine&#8212;on the chemical composition of soil organic matter in a boreal forest in comparison to non-fertilised, inorganic fertilised (ammonium-nitrate) and C-controlled inorganic fertilised (sucrose + ammonium-nitrate) conditions. The soil organic matter was characterised using two metrics: pyrolysis GC/MS and 13C solid-state nuclear magnetic resonance (NMR), combined with enzymological and metagenomic analysis.We will be presenting the results following 4-year of the fertiliser treatments. Preliminary results have shown that there is limited evidence that the fertiliser treatments alter soil C/N cycing in four years. Nevertheless, the chemical composition in SOM under the organic fertiliser condition was similar to that under C-controlled compared to inorganic fertiliser treatment.&#160;

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Effects of snow manipulation on larch trees in the taiga forest ecosystem in northeastern Siberia

Progress in Earth and Planetary Science ◽

10.1186/s40645-021-00460-5 ◽

2022 ◽

Vol 9 (1) ◽

Author(s):

Ruslan Shakhmatov ◽

Shuhei Hashiguchi ◽

Trofim C. Maximov ◽

Atsuko Sugimoto

Keyword(s):

Soil Moisture ◽

Soil Temperature ◽

Nitrogen Content ◽

Forest Ecosystem ◽

Inorganic Nitrogen ◽

Soil Inorganic Nitrogen ◽

Soil Ammonium ◽

Taiga Forest ◽

Snow Manipulation ◽

Soil Inorganic

AbstractChanges in winter precipitation (snow) may greatly affect vegetation by altering hydrological and biochemical processes. To understand the effects of changing snow cover depth and melt timing on the taiga forest ecosystem, a snow manipulation experiment was conducted in December 2015 at the Spasskaya Pad experimental larch forest in Eastern Siberia, which is characterized by a continental dry climate with extreme cold winters and hot summers. Variables including soil temperature and moisture, oxygen and hydrogen isotope ratios of soil moisture and stem water, foliar nitrogen and carbon contents and their isotopes, phenology, and soil inorganic nitrogen were observed at snow removal (SNOW−), snow addition (SNOW+), and CONTROL plots. After snow manipulation, the soil temperature at the SNOW− plot decreased significantly compared to the CONTROL and SNOW+ plots. At SNOW− plot, snowmelt was earlier and soil temperature was higher than at other plots during spring because of low soil moisture caused by less snowmelt water. Despite the earlier snowmelt and higher soil temperature in the SNOW− plot in the early growing season, needle elongation was delayed. Leaf chemistry also differed between the CONTROL and SNOW− plots. The needle nitrogen content in the SNOW− plot was lower in the middle of July, whereas no difference was observed among the three plots in August. The soil inorganic nitrogen content of each plot corresponded to these results. The amount of soil ammonium was lower in the SNOW− plot than in the other plots at the end of July, however, once production started in August, the amount of soil ammonium in the three plots was comparable. Extremely low soil temperatures in winter and freeze–thaw cycles in spring and dry soil condition in spring and early summer at the SNOW− plot may have influenced the phenology and production of soil inorganic nitrogen.

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Effects of Snow Manipulation on Larch Trees in the Taiga Forest Ecosystem in Northeastern Siberia

10.21203/rs.3.rs-753116/v1 ◽

2021 ◽

Author(s):

Ruslan Shakhmatov ◽

Shuhei Hashiguchi ◽

Trofim C. Maximov ◽

Atsuko Sugimoto

Keyword(s):

Soil Moisture ◽

Soil Temperature ◽

Nitrogen Content ◽

Forest Ecosystem ◽

Inorganic Nitrogen ◽

Soil Inorganic Nitrogen ◽

Soil Ammonium ◽

Taiga Forest ◽

Snow Manipulation ◽

Soil Inorganic

Abstract Changes in winter precipitation (snow) may greatly affect vegetation by altering hydrological and biochemical processes. To understand the effects of changing snow cover depth and melt timing on the taiga forest ecosystem, a snow manipulation experiment was conducted in December 2015 at the Spasskaya Pad experimental larch forest in Eastern Siberia, which is characterized by a continental dry climate with extreme cold winters and hot summers. Variables including soil temperature and moisture, oxygen and hydrogen isotope ratios of soil moisture and stem water, foliar nitrogen and carbon contents and their isotopes, phenology, and soil inorganic nitrogen were observed at snow removal (SNOW−), snow addition (SNOW+), and CONTROL plots. After snow manipulation, the soil temperature at the SNOW− plot decreased significantly compared to the CONTROL and SNOW+ plots. At SNOW−, snowmelt was earlier and soil temperature was higher than at other plots during spring because of low soil moisture caused by less snowmelt water. Despite the earlier snowmelt and higher soil temperature in the SNOW− plot in the early growing season, needle opening and shoot elongation were delayed. Leaf chemistry also differed between the CONTROL and SNOW+ plots. The needle nitrogen content in the SNOW− plot was lower in the middle of July, whereas no difference was observed among the three plots in August. The soil inorganic nitrogen content of each plot corresponded to these results. The amount of soil ammonium was lower in the SNOW− plot than in the other plots at the end of July, however, once production started at the end of August, the amount of soil ammonium in the three plots was comparable. Extremely low soil temperatures in winter and freeze-thaw cycles in spring at the SNOW− plot may have affected these results.

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