O3 :: Heather or Ling

Submitted by Eleanor Campbell on Thu, 11/08/2011 - 09:50
Latin name: 
Calluna vulgaris

Impact Type: Direct exposure to pollutant

Key Concerns:

Foot et al. (1996, 1997) have shown that heather (Calluna vulgaris) exposed to O3 has an increased susceptibility to damage from frost. This, coupled with the reduced frost hardiness due to exposure to NO2 and SO2 (Caporn et al. 2000), could have a significant effect. However, no significant effect of O3 exposure on the growth or health of Calluna has been found in summer so it is difficult to judge the potential effect of this interaction (Foot et al. 1996, 1997). The timing is relevant since peak O3 concentrations generally occur in summer.

Additional Comments:

None. 

Critical Load/level: 
Habitat/ Ecosystem Type Critical Load/ Level Status Reliability Indication of exceedance Reference
Semi-natural vegetation

AOT40 3000ppb hours over 3 months or AOT40 5000ppb over 6 months

 UNECE, 2010 expert judgement i.e. only limited or no data are avaliable for this type of receptor

AOT40 is the Accumulated concentration Over a Threshold of 40 ppb. If an hourly average ozone concentration exceeds 40 ppb the difference between the concentration and 40 ppb is added to a running total. The units are therefore ppb multiplied by hours. For natural vegetation, the AOT40 is summed for the daylight hours for a period of three months. Daylight hours are defined as when solar radiation exceeds 50 W m-2. The daylight hours are when plant stomata are normally open.

Flux-based critical levels, based on biomass reduction, are also available for local and regional assessment but are not yet incorporated into APIS. See critical levels chapter of the UNECE Mapping Manual.

 861
References: 
Caporn, S.J.M.; Ashenden, T.W.; Lee, J.A. 2000 The effect of exposure to NO2 and SO2 on frost hardiness in Calluna vulgaris Environmental and Experimental Botany 43 111-119
Caporn, S.J.M.; Carroll, J.; Lei, Y.; Song, W.; Read, D.J.; Lee, J.A.; Battarbee, (Eds) R.W. 1994 Acid Rain and its Impact: The Critical Loads Debate 146-150
Caporn, S.J.M.; Cockerill, G.J.; Lee, J.A. 1990 Acidic Deposition, its nature and impacts, Glasgow Conference Abstracts Effects of atmospheric nitrogen deposition on upland Calluna vulgaris 113
Foot, J.P.; Caporn, S.J.M.; Lee, J.A.; Ashenden, T.W. 1996 The effect of long-term ozone fumigation on the growth, physiology and frost sensitivity of Calluna vulgaris New Phytologist 133 503-511
Foot, J.P.; Lee, J.A.; Caporn, S.J.M.; Ashenden, T.W. 1997 Evidence that ozone exposure increases the susceptibility of plants to natural frosting episodes. New Phytologist 135 369-374
Species group: 
Vascular Plants
Pollutant: 
Ozone (O3)