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| Titel |
A new Open Top Chamber designed to test in situ effects of climatic and atmospheric changes on nitrogen fixation in boreal forest floor mosses |
| VerfasserIn |
Charline Bringuier, Robert Bradley, Jean-Philippe Bellenger, Hubert Morin, Zoë Lindo |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087047
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| Publikation (Nr.) |
 EGU/EGU2014-1019.pdf |
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| Zusammenfassung |
| Biological nitrogen fixation (BNF) by cyanobacteria dwelling in forest floor moss layers is an
important determinant of boreal black spruce forest productivity. Recent studies have
suggested that these BNF rates may increase with increasing atmospheric CO2 and increasing
temperature, as predicted by current weather models. This potential increase in BNF may be
offset, however, by increasing atmospheric deposition of nitrogen, or by increasing demands
for phosphorus (i.e. driving nodular ATP content) and for micronutrients such as Mo, Va
and Fe (i.e. co-factors of nitrogenase enzyme). In order to study the relative and
interactive effects of these factors controlling in situ BNF rates in boreal forest
floor moss layers, a new Open Top Chamber (OTC) was developed in summer
of 2013. The chambers measure 1.60 cm dia. x 60 cm height, and are equipped
with an automated CO2 delivery system designed to maintain atmospheric daytime
CO2 concentrations at 800 ppm, as well as buried heating coils that increase soil
temperature by 4 °C for 3 weeks in springtime. These 2 experimental factors are crossed
in a full factorial (2 x 2) design that is replicated in 4 complete blocks. Each of
the 16 OTCs is divided into 4 compartments, each of which are assigned 1 of 4
sub-plot factors. These include chronic additions of either atmospheric nitrogen,
phosphorus, micronutrients or a non-amended control. Staring in summer 2014, a series of
measurements will be made to assess the effects of treatments on BNF rates, cyanobacterial
colonization and soil nitrogen cycling. Our poster will describe in detail the design
and operation of the OTCs, as well as their construction and maintenance costs. |
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