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.
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The ICP-Forest methodology was used as the basis for the establishment and survey of permanent plots. Sample plots were set up in pine and spruce stands, mostly mature and overmature. When a sample plot was established, the position of the central tree was recorded, from which 6 trees were surveyed on four sides at a distance of 25 m, i.e. a total of 24 trees. Only trees 1 and 2 of Kraft's classes were taken into account. These trees were surveyed and the sampling area was described according to the ICP-Forest methodology. This methodology was supplemented by a continuous enumeration of all trees of the main tree species, spruce or pine, included in a thickness step of 8 cm or more, using two centimetre thickness steps. The enumeration was carried out in the resulting square bounded by groups of trees accounted for using the ICP-Forest methodology. Its side was 35.4 m, and the area was 0.125 ha. When carrying out a complete inventory, the status of conifers was assessed according to the generally accepted six-point scale, whereby healthy trees belong to the first category and old deadwood, i.e. deadwood of last year or earlier years, to the sixth (Mozolevskaya et al., 1984). In the presence of current year stem pest settlements, the tree was assigned to the fifth category of condition (fresh deadwood) regardless of crown condition. Stem pest species were identified by damage, larvae and adults. Pathogenic fungi and diseases were identified by fruiting bodies and characteristic features. In almost every case, the number of trees counted exceeded 100. In the Karelian Isthmus forest districts, were used sample sites set earlier by ICP-Forest methodology. In spruce forests, 27 sampling plots were set and surveyed, and in pine forests, 30. The sample sites were mainly located in the Roschino forestry unit. In the Lisino Teaching and Experimental Forestry Unit, 30 samples were placed in spruce forests of Perinskoe, Lisinskoe and Kastenskoe subdivision forestries.