The condition of coniferous forests in the Leningrad region: data on permanent experimental plots for 2021

Initial release of the dataset contains raw data obtained from spruce plots. This data was gathered with the financial support of the project No. 21-16-00065 “The role of insects and pathogens in the weakening and death of coniferous stands in the North-West of the Russian Federation: quantification and monitoring” funded by the Russian Science Foundation.