We have analysed tree growth and stand structure of transitional bogs on Pohorje. 4 research plots of an area of 200 m2 on the peat bog Petinove jame and 5 research plots on the peat bog Klopnovrška barja were established. Growing conditions are less favourable on the peat bog Petinove jame, which is more ombrotrophic. Furthermore, reference plots with an area of 400 m2 were established adjacent to each bog in the forest on the automorphic soil. Structural characteristics of trees on plots were measured and stem analysis of 30 trees on each plot was performed. Trees on the peat bog Petinove jame are lower than those on peat bog Klopnovrška barja and have smaller diameters at breast height, root collar diameters, height increment and diameter increment. Trees on bogs have clustered distribution, and trees on reference plots have random distribution. In the 19th and 20th century, drainage ditches were excavated, which is reflected on increased tree emergence and tree growth in years after excavation. With moving away from drainage ditches, tree density, basal area, root collar basal area, growing stock, average diameter at breast height, age, height and variability of height structure and variability of diameter structure of trees are decreasing. However, this decrease is generally not statistically significant. Aboveground competition does not influence the diameter and basal area increment on the peat bog Petinove jame, but does it so on the peat bog Klopnovrška barja. Chronologies for both bogs have been made and they correspond well to one another. Precipitation in April and May has a negative impact on tree growth on bogs. We found that the structure, functions and partly the area of habitat type Transition mires and quaking bogs are constantly changing, and that they are threatened by climate change and human activity. Due to global warming, the transitional bogs are intensely overgrown and their size is gradually decreasing.
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