Home – Home – Jornals – Contemporary Problems of Ecology 2015 number 1

The effect of spring defoliation on different aspects of growth and metabolism of 10–year Scots pine trees (Pinus sylvestris L.) in natural stands of the Krasnoyarsk forest-steppe region were studied. These aspects included the structure of annual xylem and phloem increments, the content of starch and photosynthetic pigments in phloem, and the activity of antioxidative enzymes in xylem and phloem. It was shown that defoliation caused reduction of shoot elongation, as well as decrease of length and mass of needles, and width of annual rings in xylem and phloem. It also stimulated late wood formation, increase in total contents of photosynthetic pigments in the needles of newly formed shoots, and reduction of starch contents in stems’ phloem. Significant increase of peroxidase activity in the xylem of defoliated trees can be a sign of oxidative stress. Defoliation had an evident negative effect on the formation of the annual rings of xylem, but didn’t have that strong impact on phloem genesis. In general, during defoliation the reserve function of the trees prevailed over the growth function.