Studies on Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) needle cuticles

Abstract

The foliar response of conifers to simulated acid rain has been ranked as less sensitive (Percy, 1987). However, the cuticular permeability and structural integrity have revealed a wide range of responses. The K+ penetration through isolated cuticles of Norway spruce was lower than that of pine cuticles. This could be caused by needle age differences. The pine needles were about 20 d old, whereas the spruce needles were over 30 d old. An age difference of 10 d can be of importance in young needles. Percy (1987) found increased foliar uptake of 86Rb at pH 2.6 in one clone of Sitka spruce. ton mobility within leaves or needles was only affected at pH 2.6. Our observations of increased K+ penetration after acid rain treatment at pH 3.0 are similar. Damage to forest trees in northern areas has been attributed to the acid deposition and cold climate. The young needle development seems to be one of the phases most sensitive to acid rain.