Impact Type: Direct exposure to pollutant
The health of Scots pine in central and western Europe, and in forests such as Thetford, may be affected by increased atmospheric ammonia emissions from intensive livestock farming. Symptoms include needle yellowing, needle loss and large concentrations of N in the foliage. While this problem is largely associated with the Netherlands, there is evidence of damage to Scots pine in the vicinity of intensive animal farms in Scotland (Pitcairn et al. 1998).
Visible damage (including needle loss and yellowing) was observed on Scots pine at sites close to livestock buildings in Scotland, and increased foliar nitrogen and reduced potassium concentrations were measured (Pitcairn et al. 1998). Current year needle concentrations of N were large at 2.3 %, exceeding critical tissue concentrations for damage to Scots pine of 2.2 % reported in the Netherlands (van der Eerden et al. 1998). In the Peel area of the Netherlands where intensive animal husbandry occurs, foliar N content of Scots pine, increased from an average of 1.5 % in 1956 to 2.3 % in 1988, and increased susceptibility to drought stress and fungal disease was observed (de Vries et al. 1995). German studies also found a strong effect of NH4+/NH3 emissions from a poultry house on the vitality of Scots pine (Kaupenjohann et al. 1989).
In the very close vicinity up to 50m damage may be direct although initially on most sites there may be growth stimulation. Increasing deposition will enhance foliar N concentrations, paralleled by an increase in amino acids e.g.Arginine. This will increase the risk of herbivore, pest and pathogen damage, and suppress root uptake of NO3-. A reduced carbon allocation to the roots will increase the risk of drought which can be exacerbated by the negative impacts of NH3 on the stomatal opening. The diversity of associated mycorrhiza is expected to reduce.
|Habitat/ Ecosystem Type||Critical Load/ Level||Status||Indication of exceedance||Reference|
3 µg NH3 m-3 annual mean (uncertainty of 2-4 µg NH3 m-3)
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.