The article focuses on improving the accuracy of predicting tree growth in young forests in Sweden. Researchers studied Norway spruce and Scots pine plantations to evaluate site productivity and growth models. They found that the current Swedish system for classifying site index may underestimate the yield capacity of Norway spruce stands. Differences in site index between stands established before and after 1940 were attributed to varying establishment and silvicultural practices. New models for predicting tree growth in young stands were developed, with some models excluding tree age as a predictor due to uncertainty in age determination. Overall, site productivity was indirectly modeled through factors like temperature and site conditions, leading to more accurate growth forecasts.