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| Titel |
Nitrogen availability in mountain spruce forest floor after forest defoliation |
| VerfasserIn |
Karolina Tahovská, Jiri Kopacek, Hana Šantrůčková |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250039861
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| Zusammenfassung |
| Spruce forests in the Bohemian Forest Mountains (Czech Republic) have been
endangered by bark beetle attack (Ips typographus) since the 1990s and, at present,
a large area of the forest has already been affected. Many deforestation studies
showed that nitrogen (N) leaching from soil increased after forest decline, however, it
is still unclear whether lower N immobilization (by vegetation and microbes) or
higher microbial N mineralization is the main mechanism affecting the change in N
balance. The aim of our study was to evaluate whether lower N immobilization
by spruce trees (Picea abies) or higher microbial N mineralization in the soil is
the main mechanism changing the soil N balance after forest defoliation induced
by bark beetle infestation. In the long term study we measured in situ mineral N
availability (N-NH4 and N-NO3)using ion exchange resins, net N mineralization (Nmin,
ammonification and nitrification), microbial carbon mineralization (Cmin) and
N content in microbial biomass (Nmic) in the forest floor of bark beetle infested
and control plots in an unmanaged area of The Bohemian Forest National Park. In
situ N availability increased before the defoliation culminated (17 vs. 165 mg N
m-2d-1), which affirms the primary effect of reduced N immobilization by trees. N
mineralization was significantly enhanced after maximum forest defoliation (2 vs. 30 μg N
g-1d-1) due to high litter input with more favourable C:N ratio. The contribution
of Nmin to in situ available N was supported by the correlations found between
in situ mineral N availability and Nmin - to - Nmic and Nmin - to - Cmin ratios. |
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