RESUMO
The data paper refers to the research article "Assessment of spatial stand structure of hemiboreal conifer dominated forests according to different levels of naturalness" [1]. Forest ecosystem structure was quantified by using structural indices based on the nearest-neighborhood approach for individual trees. Species mingling, deadwood mingling, deadwood distribution, diameter differentiation and the uniform angle indices characterize the patterns of the complexity and diversity of forest ecosystems, including the arrangement of tree dimensions, species and deadwood as well as tree positioning regularities. The data is collected all over Estonia from the Estonian Network of Forest Research Plots; altogether 212 sample plots were used in this study. The plots of the Estonian Network of Forest Research Plots are re-measured in nature with an interval of five years. Forests were classified by their naturalness level as managed forests, recovering forests and natural forests. The information in this paper can be used by forest inventories for developing the methods of ecosystem naturalness assessment as well as for analysing naturalness, stand structures and tree patterns in hemiboreal forest ecosystems.