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| Titel |
Three years exclusion of large herbivores in a high arctic mire in NE Greenland resulted in changed vegetation density and greenhouse gas emission and uptake |
| VerfasserIn |
Julie M. Falk, Niels Martin Schmidt, Torben R. Christensen, Mads C. Forchhammer, Marcin Jackowicz-Korczynski, Lena Strom |
| 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 |
250089523
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| Publikation (Nr.) |
 EGU/EGU2014-3728.pdf |
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| Zusammenfassung |
| Herbivory is an important part of many ecosystems and their presence effects the ecosystems
carbon balance with both direct and indirect effects. Little is known about what will happen
to an arctic ecosystem that is influenced by herbivory, if the animals disappear. We
hypothesized thattramplingand grazing by large herbivores influence thevegetation
density and composition and hereby the carbon balance.
Method: In 2010 an in-situ field experiment in Zackenberg, NE Greenland, were initiated
to study the effects of herbivory on the vegetation and carbon balance. Exclosures
were established to exclude the muskoxen(Ovibos moschatus), which are a natural
part of theseecosystems.The experiment consists of five block replicates with
three treatments within each block, i.e., control, exclosure and a snow fence (the
treatment area is 10x10 m and the fences are 1 m high). During the growing season
we have since 2011 performed weekly measurements of CO2and CH4fluxes, the
concentration of labile substrate for CH4 formation (organic acid concentration)
in pore-water and additional ecosystem properties, i.e., water table depth, active
layer depth and soil temperature. In 2013 a detailed analysis of the vascular plant
species composition and density within each measurement plot were performed.
Furthermore biomass (including mosses) samples 20x20 cm were harvested within all
treatments.
Results: The third year after the initiation of the experiment we observed a clear
effect of excluding muskoxen grazing from the ecosystem. The exclosures had
lower uptake of CO2and lower CH4emission. The vegetation analysis inside the
plots showed a decrease in total number of vascular tillers and ofEriophorum
scheuchzeri(ES) tillers. Correspondingly, the biomass samples from the exclosures had
lower number of total plant tillers, ES tillers, total green leaves and green ES leaves
and the height of all vascular plants and of ES plants were higher. Finally, the dry
weight of the biomass showed that there were more mosses and old biomass inside
exclosures.
Conclusions: Removing muskoxen grazing and physical presence has dramatic
effects on the ecosystem. As there is notramplinginside the exclosures the mosses
become more dominating and starts togrow upwards, due to less compaction. As
there is noconsumptionof the vascular plants, all the old biomass remains on
theground surface, most likely leading to light limitation of thevascularplants and they
thereforedecrease in number of tillers and in green leaves. The thicker moss layer forces
the vascular plants to grow taller, as seen inside the exclosures. The decrease of
CO2uptake can partly by explained by the lower number of vascular plants, while the
decrease in CH4emissionmost likely is connected to lower CO2uptake, less
vascular plants and lower overall carbon allocation below ground and hereby less root
exudation.
The future of the muskoxen in a changing arctic environment are uncertain, this
experiment is pointing towards the potentially large effect that herbivory has on the carbon
balance of natural ecosystems in the Arctic. |
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