O3 :: Mycorrhizal fungi

Latin name: 
Mycorrhizal fungi

Impact Type: Direct exposure to pollutant

Key Concerns:

Several experimental studies have been conducted to examine the effect of ozone on mycorrhizal fungi (Cairney and Meharg 1999). Although short term exposure of conifers to ozone may in some instances lead to increased colonisation by ectomycorrhizal fungi (Rantanen et al. 1994, Manninen et al. 1988), clear negative effects have been seen following longer term exposure or exposure at higher doses. The overall balance of evidence suggests a decline in response to ozone exposure (Reich et al. 1986, Meier et al. 1990, Edwards and Kelly 1992, Pirez-Soba et al. 1995). Since ozone does not penetrate the soil, Cairney and Meharg (199 9) note that the effects are most likely to be mediated via effects of ozone on the host plant, for example changes in photosynthesis and carbohydrate allocated to the plant roots (Anderson and Rygiewicz 1995, Dmaz et al. 1996).

Additional Comments:

Mycorrhizal fungi are an important part of the soil system, forming associations with plant roots to improve nutrient uptake. There are many species of mycorrhizal fungi contributing to soil biodiversity. Although at present the functional importance of this biodiversity on the roles of mycorrhizal fungi is not fully clear (Cairney and Meharg, 1999), many of the fungi observable in the field are the reproductive structures of mycorrhizal fungi. Reduction in mycorrhizal vitality may therefore be most apparent in loss of above ground diversity of fungal fruiting bodies.

The experimental evidence of interactive effects of ozone and acidification on mycorrhizal fungi appears to be equivocal with some studies finding effects and others not (Cairney and Meharg 1999). 

Critical Load/level: 
Critical Load/ Level

No estimate available

Anderson, C.P.; Rygiewicz, P.T. 1995 Allocation of carbon in mycorrhizal Pinus ponderosa seedlings exposed to ozone. New Phytologist 131 471-480
Cairney, J.W.G.; Meharg, A.A. 1999 Influences of anthropogenic pollution on mycorrhizal fungal communities Environmental Pollution 106 169-182
Dmaz, G.; Barrantes, O.; Honrubia, M.; Garacia, 1996 Effect of ozone and sulphur on mycorrhizae of Pinus halepensis Mille Annales des Sciences Forestihres 53 849-856
Meier, S.; Grand, L.F.; Schoeneberger, M.M.; Reinart, R.A. 1990 Growth, ectomycorrhizae and nonstructural carbohydrates of loblolly pine seedlings exposed to ozone and soil water defect Environment Pollution 64 11-27
Pirez-Soba, M.; Dueck, T.A.; Puppi, G.; Kuiper, P.J.C. 1995 Inter actions of elevated CO2, NH3 and O3 on mycorrhizal infection, gas exchange and N metabolism in seedlings of Scots pine Plant and Soil 176 107-116
Rantanen, L.; Palomaki, V.; Holopainen, T. 1994 Interactions between exposure to O3 and nutrient uptake, growth, mycorrhizal and needle ultra-structure. New Phytologist 128 679-687
Reich, P.B.; Schoettle, A.W.; Stroo, H.F.; Trojano, J.; Amundsen, R.G. 1985 Effects of O3, SO2, and acidic rain on mycorrhizal infection in northern red oak seedlings Canadian Journal of Botany 63 2049-2055
Species group: 

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