The use of light and electron microscopy to assess the impact of ozone on Norway spruce needles
Light (LM) and transmission electron (TEM) microscopy were used to study previously specified ozone symptoms in the foliage of Norway spruce. The three youngest green needle generations from twenty mature trees in two stands on sites of different soil fertility at Asa, southern Sweden, were sampled in 1999. The critical dose of ozone, expressed as AOT40, was 6362 ppb.h. LM showed ozone-specific sy
