N deposition :: Blaeberry

Impact Type: Deposition of pollutant

Key Concerns:

Blaeberry, Vaccinium myrtillus, is an important component of the understorey vegetation in native pine woodland and plays an important role in the life cycle of some birds (i.e. Capercaillie). A number of studies has shown that raised levels of N deposition lead to increased growth of grasses at the expense of ericaceous shrubs such as Blaeberry (Pitcairn et al. 1998, De Vries et al. 1995).

Additional Comments:

Blaeberry is more tolerant of shade and exposure than Calluna, and is common on heaths, moors and woods on acid soils, up to 3000m. Recent studies in Scandinavia have shown that increased N deposition increases the level of attack on Blaeberry by the leaf parasitic fungus Valdensia heterodoxa and by Lepidotera larvae. The risk of pests, and diseases will be gr eatly increased (Nordin et al. 1998, Strengbom et al. 2001). Nitrogen generally appears to increase frost hardiness, but may increase winter damage by wind when the ground is frozen. ��n;�p(�oeast-language:EN-GB'>4⁺ and NO₃^- (Risager 1998). Carfrae et al 2002 showed changes in the ratio of oxidised to reduced Nitrogen could potentially alter the balance between different Sphagnum species growing in bogs. Response to nitrogen is dependent on the availability of Potassium, and is also influenced by the height of the water table (Williams et al 1999). Nitrogen tends to accumulate in the Sphagnum as amino acids so that initially almost none of the additional nitrogen is available to other plant species. Aerts et al (1992) recorded a 4 fold increase in the growth of S. balticum in response to additions of 20 and 40 kg N in Sweden (background 0.4 kg N ha^-1 yr-1). Growth stimulation is phosphorous dependent.