Changes during twelve years in three mature hemiboreal stands growing in a radiation model intercomparison test site, Järvselja, Estonia

In 2007, three mature hemi-boreal stands were selected from Järvselja forest district, South-East Estonia to establish one-hectare-large test plots for the international inter-comparison experiment of radiation models (RAMI). All trees with a stem diameter at breast height greater than 4 cm were mapped and measured in the field. In summer 2019, the forests were inventoried again. Here we present a summary of changes that occurred in the forest structure – mainly growth and mortality. In the birch stand basal area G has increased from 23.3 m² ha^-1 to 28.2 m² ha^-1 in the upper layer and the number of trees N has decreased from 654 to 565 ha^-1. In the upper layer of spruce stand G has increased from 30.9 m² ha^-1 to 35.4 m² ha^-1 and N has decreased from 774 to 724 ha^-1 and N substantially decreased in the lower layers from 912 to 577 ha^-1. In the pine stand G has increased from 28.3 m² ha^-1 to 29.1 m² ha^-1 and N decreased from 1116 to 971 ha^-1. The three test stands can be used now for validating remote sensing data-based estimates of forest inventory variables at single tree level.