Peculiarities of Lime Woods in the Lisino Forestry of the Training Forest District
The target of research were the lime woods of the Leningrad region. The studies were carried out on two permanent study areas established by the authors in May 2013 in the forest compartment no. 71 of the Lisino District Forestry of the Training Forest District of the Leningrad Region. The goal of research was to obtain a complex characteristic of biogeocoenoses in plantations represented by linden, which was a rare cladotype formation in the north of its growing area. It was one of the objects of special protection of the Lisino Reserve. The objective of the research included a taxation and geobotanical description on permanent study areas, and studying the soil cover. To obtain morphological and agrochemical characteristics of soils, we established 2 soil pits, one for each sample plot, and carried out a morphological description and selection of soil samples for studying the agrochemical indicators. The humus level, actual and reverse acidity (by potentiometry), combined acidity and total exchangeable bases, active forms of nitrogen (by the phenoldisulfonic method), potassium (by Peive method), phosphorus (by Kirsanov method) were determined in the soil samples of each horizon. Based on the results of complete enumeration of plantations on sample plots, we calculated the average taxational indicators. The general condition of plantations in the surveyed areas was satisfactory (mean score was 2.5 and 2.8). Lime woods in the sample plots were attributed to a nemorose-herb series of forest types, soils - to a podzolic type with a weak development of the podsol-forming process. They were wellmediated by humus in the upper horizon. This fact was facilitated by the lime litter, which had a deep root system to take up nutritional chemicals from a greater depth, where moraine loams enriched with calcium carbonate were located. Old-aged forests of this type were in the phase of “window” dynamics. This means that they can occur for a rather long time in the same place, however, the lime woods are the cladotypes of the warm Atlantic period of the Holocene and their existence is constantly under threat of spruce change. Morphological studies show that ashen gray soils with poorly expressed podsol-forming process are formed in the diffuse eskar due to the free drainage of sandy grounds formed on carbonate-free layers with a low content of active forms of mineral elements, characteristic of sand and sandy loam. The results of our study show that low levels of soil mineral nutrients supply are sufficient for the successful linden growth.