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| Titel |
Fire recurrence effects on aboveground plant and soil carbon stocks in Mediterranean shrublands with Aleppo pine |
| VerfasserIn |
J. Herman, J. den Ouden, G. M. J. Mohren, J. Retana, I. Serrasolses |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028660
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| Zusammenfassung |
| Changes in fire regime due to intensification of human influence during the last decades led to
changes in vegetation structure and composition, productivity and carbon sink strength of
Mediterranean shrublands and forests. It is anticipated that further climate warming and
lower precipitation will enhance fire frequency, having consequences for the carbon budget
and carbon storage in Mediterranean ecosystems. The purpose of this study was to determine
whether fire recurrence modifies aboveground plant and soil carbon stocks, soil organic
carbon content and total soil nitrogen content in shrublands with Aleppo pine on the Garraf
Massif in Catalonia (Spain). Stands differing in fire frequency (1, 2 and 3 fires since 1957)
were examined 13 years after the stand-replacing fire of 1994 and compared with
control stands which were free of fire since 1957. Recurrent fires led to a decrease
in total ecosystem carbon stocks. Control sites stored 12203 g m-2C which was
3.5, 5.0 and 5.5 times more than sites that burned 1, 2 and 3 times respectively.
Carbon stored in the aboveground biomass exceeded soil carbon stocks in control
plots, while soils were the dominant carbon pool in burned plots. An increasing fire
frequency from 1 to 2 fires decreased total soil carbon stock. Control soils stored
3551 g m-2C, of which 70 % was recovered over 13 years in once burned soils and
approximately 50 % in soils that had 2 or 3 fires. The soil litter (LF) layer carbon
stock decreased with increasing fire frequency from 1 to 2 fires, whereas humus (H)
layer and upper mineral soil carbon stocks did not change consistently with fire
frequency. Fire decreased the organic carbon content in LF and H horizons, however
no significant effect of fire frequency was found. Increasing fire frequency from
1 to 2 fires caused a decrease in the organic carbon content in the upper mineral
soil. Total soil N content and C/N ratios were not significantly impacted by fire
frequency. Recurrent fires had the greatest impact on aboveground plant carbon stocks.
Aboveground plants in control plots amounted to 8652 g m-2C, of which 93 % was stored
in trees, while carbon storage in the most frequently burned sites was only 509 g
m-2C. Shrub carbon varied barely between fire frequencies, corroborating the high
resilience of resprouting shrub species to fire recurrence. The most striking result was
the immense decrease in Aleppo pine carbon stock which varied between 7770 g
m-2in control plots and 25.6 g m-2in 3-fires plots. Differences between control
and burned plots are principally explained by the age of the plots. The decrease in
Aleppo pine carbon stock within burned plots was not associated with a growth
reduction, but was due to a decrease in stem density. The results indeed indicate
that the recruitment of Aleppo pine on more frequently burned plots is obstructed
due to cumulative effects of short fire return-intervals ( |
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