A. Gorissen et Tw. Kuyper, Fungal species-specific responses of ectomycorrhizal Scots pine (Pinus sylvestris) to elevated [CO2], NEW PHYTOL, 146(1), 2000, pp. 163-168
Ectomycorrhizal seedlings of Scots pine (Pinus sylvestris) inoculated with
the nitrotolerant Laccaria bicolor and the nitrophobic Suillus bovinus were
exposed to ambient (350 mu l 1(-1)) and elevated (700 mu l 1(-1)) [CO2]. A
fter 79 d the seedlings were labelled for 28 d with (CO2)-C-14, after which
they were harvested. C-14 was determined in shoots, roots plus mycorrhizas
, soil, and below-ground respiration; nitrogen was determined in shoots and
roots. Total net C-14 uptake increased under elevated [CO2]. The extra car
bon did not increase the shoot mass but was translocated to the roots and r
esulted in a decreased shoot-to-root ratio in the Suillus-inoculated seedli
ngs. Laccaria-inoculated seedlings did not incorporate the additional carbo
n in root or fungal tissue but only increased below-ground respiration. S.
bovinus acquired or transferred nitrogen better than L. bicolor and enabled
the seedlings to perform better with regard to net carbon uptake under ele
vated [CO2]. This resulted in nitrogen concentrations in shoots of Suillus-
inoculated seedlings that were twice as high as in Laccaria-inoculated seed
lings, irrespective of [CO2]. The higher nitrogen concentration in the shoo
ts resulted in a doubling of the C-14 uptake per unit shoot mass. Our resul
ts suggest that the ability of ectomycorrhizal Scots pine seedlings to resp
ond positively to elevated atmospheric [CO2] is strongly fungal-species spe
cific.