Impact of fire and post-fire management techniques on soil chemical properties

Abstract

The effects of
fire (
Control
burned soil) and two emergency stabilisation techniques (grass
Seeding
and straw
Mulching
) on 20 chemical characteristics were evaluated on 0
–
5 cm top-soils sampled 1, 90, 180 and
365 days after an experimental
fi
re in a steep shrubland of a temperate-humid region (NW Spain). Most
part of pH (in H
2
O and KCl) variance was explained by the sampling date. No clear temporal trends were
identi
fi
able for total soil C and N content, likely due to the large SOM pool in these soils; however, changes
on soil
δ
13
C were explained by the deposition of
13
C-depleted ashes, followed by its progressive erosion,
while those on soil
δ
15
N were a consequence of
fi
re induced N outputs. After the
fi
re, NH
4
+
–
N, P, Na, K, Mg,
Ca, Mn, Cu, Zn and B concentrations increased, while those of NO
3
−
–
N, Al, Fe and Co did not vary significantly.
Despite a significant decline with time, concentrations of Mg, Ca and Mn at the end of the study were still
higher than in unburned soil, while those of K, Cu, Zn and B were similar to the pre-fire levels and those of
NH
4
+
–
N, P and Na were below pre-fire values.
Mulching
and
Seeding
treatments for burned soil emergency
stabilisation had significant effects on soil
δ
15
N and extractable K, Mg and Ca, while data were inconclusive
for their possible effects on the extractable Al, Fe and Co