NH3 :: Ferns (general)

Latin name: 

Impact Type: Direct exposure to pollutant

Key Concerns:

Available evidence suggests that ferns are sensitive to elevated ammonia concentrations (Schumann and Mills 1996, Pitcairn et al. 1998). Measurements of Pitcairn et al. (1998) showed changes in Dryopteris dilatata abundance near to intenstive livestock farms.

Additional Comments:

Burkhardt et al. (1998) have shown that the critical level for N deposition is normally exceeded before the critical level for NH3 exposure is reached. While relatively shade tolerant, carbon fixation is fundamental to N assimilation, thus overgowth by trees and more nitrophilous vegetation may weaken the capacity of ferns to tolerate NH3. Some ferns e.g. Dryopteris dilata (Broad bucker fern) are nitrophites (nitrogen lovers) - these will be more tolerant of NH3 and may respond positively.

Critical Load/level: 
Habitat/ Ecosystem Type Critical Load/ Level Status Indication of exceedance Reference
Higher plants

3 µg NH3 m-3 annual mean (uncertainty of 2-4 µg NH3 m-3)

UNECE, 2007

Direct visible injury; species composition changes. Ecosystems where sensitive lichens and bryophytes are an important part of the ecosystem integrity, the critical level is set at 1 µg NH3 m-3.

Burkhardt, J.; Sutton, M.A.; Milford, C.; Storeton-West, R.L.; Fowler, D. 1998 Ammonia concentrations at a site in southern Scotland from 2 yr of continuous measurements Atmospheric Environment 32 325-331
Pitcairn, C.E.R.; Leith, I.D.; Sheppard, L.J.; Sutton, M.A.; Fowler, D.; Munro, R.C.; Tang, S.; Wilson, D. 1998 The relationship between nitrogen deposition, species composition and foliar nitrogen concentrations in woodland flora in the vicinity of livestock farms. Environmental Pollution 102 41-48
Schumann, A.; Mills, H.A. 1995 Injury of leatherleaf fern and tomato from volatilized ammonia after fertilizer application. Journal of Plant Nutrition 19 573-593
Species group: 

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