N deposition :: Twinflower

Latin name: 
Linnaea borealis

Impact Type: Deposition of pollutant

Key Concerns:

Twinflower, Linnaea borealis, which is adapted to very nutrient poor sites (Hill et al. 1999), is a priority species in the Scottish Biodiversity Ac tion Plan (Usher 2000) and is also listed in the UK BAP. It is found in pine woodland in eastern and northern Scotland. It has been declining since the turn of the 20th century. Increases in nitrogen deposition, which have been observed to affect woodland ground flora (Pitcairn et al. 1998), may be contributing to this decline by encouraging growth of fast growing competitors.

Additional Comments:

Westlund and Nohrstedt (2000) have shown that in Sweden the use of urea in the treatment of cut tree stumps substantially increases local ammonium concentrations and causes severe damage to understorey vegetation killing L. borealis by direct toxicity. 

Critical Load/level: 
Habitat/ Ecosystem Type Eunis Code Critical Load/ Level Status Reliability Indication of exceedance Reference
Broadleaved deciduous woodland G1

10-20 kg N ha-1 year-1

UNECE 2010 - Noordwijkerhout workshop reliable

Changes in soil processes, nutrient imbalance, altered composition mycorrhiza and ground vegetation.

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References: 
Hill, M.O.; Mountford, J.O.; Roy, D.B.; Bunce, R.G.H. 1999 Ellenberg's indicator values for British plants: ECOFACT volume 2 technical annex.
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
Usher, (Eds) M.B. 1999 Action for Scotland's Biodiversity
Westlund, A.; Nohrstedt, H.O. 2000 Effects of stump-treatment substances for root-rot control on ground vegetation and soil properties in a Picea abies forest in Sweden Scandinavian Journal Forest Research 15550-560 550-560
Species group: 

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