Northern environment predisposes birches to ozone damage

• Ozone sensitivity of silver birch (Betula pendula Roth) has been thoroughly investigated since early 1990's in Finland. in our long-term open-field experiments the annual percentage reduction in basal diameter and stem volume increment were the best non-destructive growth indicators for ozone impact when plotted against AOTX. Remarkable differences in defence strategies, stomatal conductance, and defence compounds (phenolics), clearly indicate that external exposure indices are ineffective for accurate risk assessment for birch. For flux-based approaches, site-specific values for g(max) and g(dark) are necessary, and determinants for cletoxification capacity, ageing of leaves, and cumulative ozone impact would be needed for further model development. increasing CO2 seems to counteract negative ozone responses in birch, whereas exposure to springtime frost may seriously exacerbate ozone damage in northern conditions. Therefore, we need to proceed towards incorporating the most important climate change factors in any attempts for ozone risk assessment.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

ozone

birch

open-field experiment

northern europe

risk assessment

aot40

afsty

betula-pendula roth

carbon-dioxide

silver birch

elevated concentrations

chemical-composition

springtime frost

growing seasons

responses

exposure

leaves

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)