Question: How do vascular plant and cryptogam cover, bare peat area and species composition in different microforms on a boreal raised bog change over a 34-year period (1988–2022)? We discuss the observed patterns in the light of ongoing climate change. Location: Rønnåsmyra Nature Reserve, south-eastern Norway. Methods: We recorded total vascular plant and cryptogam cover, bare peat area and species composition in 51 permanent 0.5 × 0.5 m plots in 1988, 2004 and 2022. The plots were assigned to microform classes (carpet, lawn, hummock) based on their characteristics in 1988 and 2022. We analysed changes over time and explored the relationship between change in species composition and change in the relative distance from the bog surface to the groundwater table (rDWT) in each microform using linear mixed-effect models and ordination (GNMDS). Results: No shifts between microforms had occurred during the 34-year period, but the number of observed taxa had decreased from 51 to 38. While the vegetation changed very little between 1988 and 2004, substantial changes occurred from 2004 to 2022. During this period, carpets showed a substantial increase in bare peat at the cost of cryptogam and vascular plant cover. Lawns showed a similar but less strong trend. Hummocks showed no such changes. The species composition of all microforms changed towards vegetation typical of wetter bog surfaces. In hummocks, this implied a shift from dominance by lichens to dominance by strongly peat-producing Sphagnum species of section Acutifolia, coupled with an increase in rDWT. Conclusion: We demonstrate that bog vegetation can change substantially within two decades. The observed, divergent successions—retrogressive in carpets and lawns and progressive in hummocks—may result from the responses of the cryptogam layer to a combination of increased temperature and increased precipitation. Extreme weather events may have contributed to the increase in bare peat. Keywords: boreal raised bog | climate change | groundwater table | long-term monitoring | microform | ombrogenous mire | peatland | short-cycle regeneration | succession | vegetation dynamics.