Fræðaþing landbúnaðarins - 16.02.2007, Side 414

412 • Fræðaþing landbúnaðarins 4, 2007
production and accumulation of organic matter. Furthermore, retention of P is high (>
90 %) in Icelandic Andisols (Amalds et al. 1995). Consequently, a possible change in P
forms and thus the P supply of trees cannot be excluded in the present study, although
total P content remained constant. Soluble P has been measured and will be discussed
elsewhere. Also the presence of mycorrhizal íungi may have a distinct effect on the
uptake of P by plant roots. Hyphae of the fungi can adsorb about twice as much P as the
root hairs of the trees and thereby increasing the influx of P in roots (Fisher and Binkley
2000).
P stocks: 0-10 cm depth P stocks: 10-20 cm depth
500
400
fi 300
O)
2*:
ZC
o 200
(/)
Q-
100
0
heath L_13 L_21 B_21 L_40 L_53 B_100 heath L_13 L_21 B_21 L_40 L_53 B_100
] larch
] birch
I heathland
V./ZA larch
7777i birch
■■■ heath land
1 i
r% i
4.
i
Wm
L
gi
I
i
Fig. 3 : Stocks of total P in two different soil depths under heath land, birch, and larch. P stocks
were significantly higher in 10-20 cm depth than in 0-10 cm depth (P < 0.001).
This study has shown so far that changes in soil nutrient stocks are much less
significant than expected. Carbon sequestration was found to be less than known from
land reclamation project with annual and perennial grasses, but more soil samples
are recommended to prove this result. An analysis of plant available forms of N and
especially P is suggested to investigate the actual nutrient supply to plants, together with
the study of mycorrhizal fungi present in the soil of the different forest stand.
References
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Shoji, S., Nanzyo, M., and Dahlgren, R. 1993. Volcanic Ash Soils. Elsevier, Amsterdam.
Oskarsson, H., Sigurgeirsson, A., and Raulund-Rasmussen, K. 2006. Survival, growth, and nutrition of tree
seedlings fertilized at planting on Andisol soils in Iceland: Six-year results. Forest Ecology and Management
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Miller, H.G. 1981. Forest fertilisation: some guiding concepts. Forestry 54: 157-167.
Pétursson, J.G. 2001. Skógræktarstarfið 2000, tölulegar upplýsingar (Forestry 2000; numerical informa-
tion). Icelandic Forestry 2: 82-84.
Smith, S.E. and Read, D.J. 1997. Mycorrhizal Symbiosis. Academic Press, San Diego, CA.