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| Titel |
Decomposition of soil organic matter by ectomycorrhizal fungi studied by infrared spectroscopy |
| VerfasserIn |
César Nicolás, Anders Tunlid, Per Persson |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102445
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| Publikation (Nr.) |
 EGU/EGU2015-1761.pdf |
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| Zusammenfassung |
| Boreal forests accumulate a fifth of the global soil organic matter (SOM) pool and play an
important role in the carbon cycling. Most trees in these boreal forests live in symbiosis
with ectomycorrhizal fungi (EMF) that sheath the plant root tips. In the symbiotic
relationship, EMF provide nutrients from the soil to plants such as nitrogen and
phosphorous, and trees give carbon in return to the fungi. When foraging for these
nutrients, EMF use different strategies to explore the soil matrix. Long-distance
exploration types grow far into the soil surroundings of the roots, while short-medium
distance exploration ones grow close to the root tips. Despite these morphological
differences among EMF, there is still little evidence of their functional role in the SOM
decomposition.
In this study, two ectomycorrhizal fungi Paxillus involutus and Laccaria bicolor,
which belong to long and medium-distance smooth exploration types respectively,
were grown in axenic cultures on SOM extracted from forest litter. To trigger the
fungal decomposing activity, the extracts were supplemented with glucose. Chemical
analysis and infrared spectroscopy were used to analyze the organic matter and
chemometric tools such as principal component analysis (PCA), two-dimensional
(2D) correlation analysis and multivariate curve resolution-alternating least squares
(MCR-ALS) analysis were applied to further understand the chemical changes in the
SOM.
The first principal component of PCA explained 77% of the total variability and separated
the treatments based on two infrared spectral regions: polysaccharides (970-1,150 cm-1) and
carbonyl region (1,620-1,800 cm-1). Moreover, the 2D correlation analysis showed
that the polysaccharides region in both treatments was negatively correlated with
the carbonyl region, suggesting the production of oxidized compounds such as
ketones during the uptake of glucose. The 2D correlation analysis also revealed
that the diminution of intensity in the polysaccharides region occurred faster than
the increase in the carbonyl region and that this change in the SOM was larger
with Paxillus involutus. The MCR-ALS analysis resulted in at least three major
components, which showed different time-response along the experiment. These
components might be attributed to different compound classes such as polysaccharides,
quinones or carboxylic acids, giving evidence of the transformation of the SOM with
time.
Overall, these results demonstrate that combination of infrared spectroscopy and
chemometrics can help to elucidate our understanding about the role of EMF in SOM
decomposition. |
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