| Summary: | Previous studies suggests that reindeer grazing lichen enhances the growth of pine trees in a pine forest in northern Finland. The aim of this study is to determine if reindeer grazing increase tree growth in other parts of the Nordic countries. Since climate is a major driver of variation in tree growth, the effect of the climate was studied by drilling 47 trees in 10 different locations on Ängesön, Holmöarna. This island has a unique grazing history since it was ungrazed for almost a century before it recently (2015) started to be used as winter pasture for reindeer again. The width of cores rings was analyzed to measure tree growth during the last 20 years, which includes the years before and after the reindeer grazing was reintroduced. Annual tree growth was also compared with climate data and tree age during the study period (2000–2019). Tree growth decreased during the study period. This was partly explained by reduced tree growth with increasing tree age. It was also related to changes in temperature and rainfall. Reindeer grazing, on the other hand, did not affect tree growth. It could be that some other factor is limiting tree growth on Ängesön than in northern Finland, or that the positive and negative effect of reindeer cancel each other out.
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