The choice of rootstock is the main precondition for establishing of high yielding and sustainable plum orchards. Therefore influence of rootstock on the plum cultivars wintering in Latvia climatic conditions becomes more and more actual. Investigation was carried out with the aim to clarify influence of rootstock on the wintering and health status of plum cultivar 'Victoria'. Investigation was carried out at Pure Horticultural Research Centre during two different wintering seasons of 2008/2009 and 2009/2010, in the orchard planted in 2001. The winter of 2008/2009 was characteristic with sharp temperature fluctuations, but winter of 2009/2010 was snowy with stable low temperatures. Sixteen widely used rootstocks known in Europe were included. Plum general tree health status (scored by 1-5 points) and percentage of dead trees were evaluated. No statistically significant differences among rootstocks were established according to the evaluation of tree health status. Differences in wintering ability among rootstocks were stated between two years of investigation. Trees grafted on Brompton seedlings and St. Julien d' Orleans demonstrated the highest winter hardiness (4.3 points). No one dead tree was registered on these two rootstocks. Rootstock GF8/1 was the least suitable for Pure conditions - with general health status scored at 2.3 points after severe winter of 2009/2010, and only 25% of alive trees.

This brief review of the recent birch studies is focused on different aspects, such as species distribution, growing conditions, species identification, changes due to environmental factors. All mentioned investigations were carried out in Lithuania. This analytical study summarises the results and increases knowledge dissemination to the international audience. When reviewed and summarized considerable part of relevant literature sources, we realised new problems and challenges; for example, aiming to clarify the peculiarities of the growth and crown condition of the dominant birch species (Betula pendula Roth. and B. pubescens Ehrh.) under the changing climate and anthropogenic pollution.

Forest fires in Latvia occur every year. Research about vegetation and forest regeneration after forest fire is being carried out in Latvia, and sanitary conditions are being evaluated too; however, there are no large studies about the forest fire impact on radial growth dynamics of trees. The aim of the study was to analyse and compare the response reaction of a forest stand after fire in two forest site types – Hylocomiosa and Vacciniosa turf. mel. The object of the research was fire affected middle–aged managed Scots pine (Pinus sylvestris L.) stands in the aforementioned forest site types. The study compares radial growth dynamics of trees, tree mortality and forest stand sanitary conditions after fire in Hylocomiosa and Vacciniosa turf. mel. The observed fire impact on radial growth dynamics of trees was negative in both forest site types. Negative fire impact on sanitary conditions was observed, too.

The objects of research are the lime-tree forests of the Leningrad region. The studies were carried out on 2 permanent plots established by the authors in May 2013 in the Lisino forest district (Leningrad region, Russia). The goal of research was to obtain a complex characteristic of stands dominated by linden (Tilia cordata). The objective of the research included a taxation and geobotanical description on permanent plots and studies of the soil cover (morphological and agrochemical characteristics of soils). The general health status of stands on the surveyed areas was determined as satisfactory – mean score 2.5 and 2.8 (relevant health status was determined with the help of the following 6-grade scale for each tree: 1 – no signs of weakening; 2 – weakened tree; 3 – very weakened tree; 4 – partial mortality of the tree; 5 – dead-standing trees of the current year; 6 – dead-standing trees of previous years). The average mortality rate varies from 3.05% year-1 on the sample plot 2 to 5.7% year-1 on the sample plot 1. Vegetation on sample plots attributes to a nemorose-herbal series of forest types, soils – to a podzolic type with a weak development of the podzol-forming process. They were well-mediated ones by humus in the upper horizon. This fact was facilitated by the lime litter: a lime has a deep root system to take up nutritional chemicals from a greater depth, where moraine loams enriched with calcium carbonate located. Old-aged forests of this type are being in the phase of gap dynamics now. This means that they can occur for a rather long time in the same place, however, the lime-tree forests of natural origin are constantly under threat of being replaced by spruce. The results of our study have shown that low levels of soil mineral nutrients supply are sufficient for the successful linden growth.