In the 1950s, the average height of a 50-year-old pine or spruce in Sweden was 12 meters. By 1992, the height was instead 15 meters.
A study conducted between 1983 and 2020 shows that a pine with 50 growth rings at breast height was 16.5 meters high in 1983, and a similarly aged pine was 18.25 meters high in 2020. The figures for spruce for the same years were 16.4 and 18 meters.
However, no significant increase in diameter was observed, which means that the trees have primarily increased in height rather than width over the past 40 years.
Similar studies have also been conducted in other countries, such as Finland, Germany, and the USA, where increases in growth have also been observed. However, the cause is still somewhat unclear.
Researchers at SLU believe that it may, among other things, be due to the increased carbon dioxide content in the air.
