 |
| Titel |
Effects of experimental repeated fires in the soil aggregation and its temporal evolution |
| VerfasserIn |
Julian Campo, Eugenia Gimeno, Vicente Andreu, Oscar Gonzalez, José Luis Rubio |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072436
|
|
|
|
|
|
| Zusammenfassung |
| Forest fires are an important problem in the Mediterranean and change our forest
topsoils with still unknown consequences for important ecosystem services, such as
water availability, plant growth and carbon sequestration. The total area affected by
forest fires in Mediterranean countries of the European Union has declined since
1980, and the number of fires in this region tends to stabilize. However, in countries
like Spain and Portugal the number of fires tends to increase. This fact seems to
support future predictions indicating a general tendency to increase the number
of forest fires, related to the climate change. According to European Forest Fire
Information System (EFFIS), 102349 ha of the Spanish forest surface were burned in the
summer of 2012 (01/06- 11/08/), of which 54186 ha were registered in the Valencia
region.
In this sense, to assess post-fire soil recovery aggregate stability has been used as an
indicator in the Experimental Station of La Concordia (Valencia, Spain), where experimental
fires were carried out in1995 and 2003, in a set of nine plots (20x4m). The soil studied is a
Rendzic Leptosol. The stability of macroaggregates (SMS, Ø >250 μm), soil organic matter
(SOM) and calcium carbonate contents, aggregates size and water erosion processes,
were analysed in relation to fire severity and its recurrence, in two environments
(under canopy, UC, and bare soils, BS), and in the short- and medium-term of two
fires.
In 1995, different fire treatments were applied to obtain different fire severities: three
plots were burned with high severity fire, other three plots with moderate one, and the
remainder plots were left unburned (control). In 2003, the same plots were burned again with
low severity fires. The study was performed until summer of 2007. In general, soil
environment explained significant differences in the soil properties between under canopy
and bare soils. Only in the short-term of repeated fires, CaCO3 content, macroaggregate mean
weight diameter (MWD) and microaggregate mean diameter (MMD) values were similar in
both soil environments.
The different severities of 1995 fires, and its recurrence in 2003, did not cause
any change in the SMS, however an upward trend was observed with final values
ranging between 35-40% in soils under canopy, and between 25-30% in the bare. The
aggregate size distribution changed significantly in the short-term of both fires
and, consequently, the final MWD decreased (~30% UC). SOM content of the UC
burned with high severity tended to decrease after the first fire, but increased in those
soils in moderate severity. Decreasing SOM trends were found in the short-term.
After the repeated fires in 2003, no change was measured. Low organic matter
incorporation was demonstrated (8-10% UC, 6.5-7.5% BS). The CaCO3 content was very
high and continued increasing after 1995 fires. There were no short-term changes
after 2003 fires, but in the medium term tended to decrease (50-55% BS, 45-50%
UC).
The organic matter seemed to be responsible of macroaggregates stability in the control
soils; meanwhile the CaCO3 had a low participation. The role of both cementing agents in
burned soils was not clearly established, although it is assumed that the high SOM content
was more important than that of CaCO3, which might have some involvement in the MMD.
Finally, it was established that runoff and sediment yields depend on fire severity, as well as
on intensity and volume precipitation. Such erosion rates were significantly higher in the
burned plots than in those unburned. Although in the medium term runoff tended to
decrease, the high sediment rates confirmed the poor recovery of burned plots. |
|
|
|
|
|
|