Soil Fertility After Fire and Clear-Cutting
323
80
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Organic-P
b
-e-- Total-P
60
a
ab
40
c
20
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Clearcutting-H
- 60
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Burned-Ashbed
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Burned-H
a
40
be
be
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b' V
bV ' V b
b V
v b
0
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200
400
600
800
Days after the fire
Fig. 22.3. Variation of soluble phosphorus (total and organic) with time. Mean of four bulk samples
and standard deviation. Different letters within each P fraction show significant (P top mineral layers of soil, most of the mineral N was ammonium. This
showed small fluctuations during the 2 years of sampling.
In the clearcut plot, 6 months after clear-cutting, mineral N concentration
increased dramatically, but in different forms and proportions depending on
the layer considered: in the H layer, mineral N was mostly nitrate and showed
the highest increase recorded; in the 0-5 cm mineral soil, both mineral forms
increased with an initial peak of nitrate; in the 5-10 cm mineral soil, ammo-