The interest in stumps has increased with recent boost of the bioenergy in Europe. Fuel yield from stumps can be as high as from harvesting residues. The most valuable areas for stump extraction are spruce and pine stands on dry mineral soils. In Finland the utilization of stumps for energy is rapidly moving from the testing phase to forest practice. In 2005 the use of stump wood chips by heating and power plants totalled 0.4 mill. m**3, tripled the consumption of 2004, which corresponds to 14% of the total consumption of forest chips in Finland. Extensive whole-tree harvesting trials in Sweden demonstrate that removal of stumps and slash from clear-felled sites has a strong positive impact on natural forest regeneration. Results from Finland indicate that stump and slash removal can improve productivity and quality of subsequent re-planting of harvested forest sites. The majority of available studies on root rot control demonstrate that subsequent forest regeneration is more successful on sites where the stumps have been removed. The scope of this study was to evaluate quality of forest regeneration after stump extraction in Finland according to the national regulations in Latvia. Number, size, distribution and mortality of seedlings were estimated in 15 compartments. Additionally, moisture and compaction of soils were determined. Results of the study approved that regeneration of forest stands on fertile mineral soils after stump extraction was successful and combination of mounding with scarification during stump extraction provides sufficient growing conditions for new seedlings.

Growing of economics and new technologies has caused the environment pollution and more intensive use of natural resources. The principles of stable and balanced forestry became more and more important. Ecologization forests economy directly and indirectly impacts environment, water, air, landscape. It is not allowed to use chemicals in ecological farms. In Lithuania the number of ecological farms is growing that is why the new effective ecological methods are needed to protect seedlings from weeds. Alternative to mechanical control of weed is to use high temperature. In ecological farms weed control after sowing time is pursued in mechanic, and recently in thermal way. In thermal weed control the surface of soil remains mechanically undisturbed, the roots of cultural plants remain undisturbed, too. These features are very important in forest nurseries, where different kinds of tree species are growing. Seedlings are very small at the beginning of growing, so mechanical weed control is difficult. Thermal weed control could be a good alternative. Comparable data of 2009-2011 thermal weed control research in Norway spruce (Picea abies (L.) H. Karst.) nursery is given. The efficiency of destroyed 16 weed sorts using thermal and mechanical ways of weed control is given. Thermal weed control for short age weeds is 20.3% more effective in comparison with mechanical way. Mechanical way is 35.2% more effective for perennial weeds. It was detected that in order to control weeds of different growth stages, it is necessary to use different treatment time of damp water stream.

With the increase in demand for renewable energy resources, new studies are carried out about under - utilized resources, namely, stumps. To begin to use stumps in industrial application, it is necessary to find out stump extraction influence on the environment, biodiversity, forest regeneration and other important factors. In Zemgale forestry, Misas and Klīves forest districts managed by Joint stock company “Latvian State Forests” (LSF) study on stump extraction in woodlands where clear-cuttings done in 2006 was carried out in the block No. 177, compartments No. 1 and 5, as well as the block No. 176, compartments No. 3 and 9. In these territories two research objects were made where in November-December 2007 stump extraction as well as soil preparation were performed. Main tasks of the project were to evaluate the results of forest natural seeding and coppice ingrowths in natural regeneration areas and evaluate the use of different methods for artificial reforestation with spruce and pine containerized seedlings. It was observed that more seedlings were cut off in the areas where soil scarification with stump extractor was performed if compared to areas prepared with a disc trencher.

Japanese quince (Chaenomeles japonica) is cultivated as a fruit crop because its fruit possesses valuable properties. The total area of Japanese quince in Latvia is continuously increasing; therefore, fruit rot can become an important reason of yield loss. The aim of this study was to clarify the fruit rot incidence in Japanese quince plantations in Latvia and explore the influencing factors of rot development in the year 2017. The evaluation of fruit rot was carried out during the fruit development in eight places of different regions of Latvia where Japanese quince is grown commercially. Three plantations of different Japanese quince cultivars in Dobele and seven plantations where Japanese quince is grown from seedlings were observed. Fruit rot incidence among plantations had no significant differences. Statistically significant differences in fruit rot incidence depending on quince growth stage (p is less than 0.05) were found. Significant differences in fruit rot incidence were found between cultivars in Dobele.

The early stage of forestry is crucial for successful and sustainable forest management. One third of the reforested forest in Latvia is regenerated by planting with different kinds of tree seedlings. The success of forest regeneration by planting depends on correctly prepared soil and choice of the right seedling material. The aim of this study was to evaluate the impact of different soil preparation methods and used type of seedlings on tree survival and growth rate after the first growing season. For this study six young stand sites located in the north-west and central part of Latvia were established in three forest types and in each site soil was prepared in furrows by disc trenching, in mound and left untreated. Reforestation was conducted in the spring of 2017 with four tree species Picea abies, Pinus sylvestris, Alnus glutinosa and Betula pendula and three seedling types were used, bare roots, containerized and improved root system. The evaluation of survival and measure of annual increment was conducted at the end of the first growing season in the autumn of 2017. Results showed that overall the highest seedling survival rate provided soil prepared in mound (90%), and seedlings with improved root system, though the lowest survival rate was observed for bare root seedlings. Containerized seedlings have a higher proportional increment if compared to bare root and improved root system seedlings, but differences are not significant yet (p is greater than 0.05). In conclusion, the survival rate of outplanted seedlings differs by chosen stocktype and soil preparation method used in forest regeneration and for various tree species impact of chosen stock type on survival rate differs.

Turkey is a mountainous country with many high mountains. Recent estimations show that there are approximately 20.7 million ha of forested area in Turkey, covering 25.8% of the total land area. However, little over half of this forested area is classified as unproductive (51.7%). Artvin is located in the North Eastern Black Sea part of Turkey and is the home of a very rich biological diversity. Forests in Artvin region are in different climatic zones - from temperate climate to continental climate zone - and there are several vegetation zones in the region which ranges from sea level to the altitude of 3500 m. A Scotch pine (Pinus sylvestris L.) plantation, planted in 1996 in the alpine zone in Artvin-Ardanuc region, was investigated. The size of study area was 40 ha and this research was done on 12 sample plots. There were 50 Scotch pine seedlings on each sample plot. Height and root collar diameter of the seedlings were measured. The mean slope was the same (60%) on the sample plots, and the effects of exposure and altitude significantly affected the height and root collar diameter growth of the seedlings (P is less than 0.05). It was determined that increased altitude is associated with decreased height growth and root collar diameter of the seedlings.

Sapropel or gyttja are the terms that relate to specific water body sediments containing a high level of organic matter formed from the remains of water biota mixed with mineral components. One of the most promising utilisation ways of sapropel is agriculture and forestry where this natural material can be used as soil amendment to enrich soil fertility, neutralise acidity, improve water capacity and reduce phytoavailablity of excess of metallic elements. The aim of this study was to perform plant germination and early seedling tests using various sapropel samples and to reveal response of plant development depending on the type of sapropel to be used as soil amendment. Pure natural sapropel and sapropel/sand substrate of such types as peaty, organic-sandy, cyanobacteria, green algae and carbonatic sapropel, derived from four lakes of eastern Latvia, were tested. Seeds of cucumber Cucumis sativus and tomato Solanum lycopersicum as dicotyledons and perennial rye-grass Lolium perenne as monocotyledon were chosen for the experiment. Seed germination and early seedling tests were performed in PHYTOTESTKIT plates. Seeds were germinated in thermostat at a temperature of 26 °C for 7 days but early seedling development was achieved after 23- 30 days (depending on plant species) under daylight conditions at a temperature of 20 °C. Developed radicles and hypocotyls were measured, shoots and roots were weighed. The obtained results showed a distinctive effect of applied sapropel type on the development of plants depending on species and substrate – substrate containing pure natural sapropel is effective for cucumber and perennial rye-grass, but not for tomato.

The tree growth compensation followed by insect damage is important for tree survival. Insect damage by making 3 and 6 holes per each leaf, and clipping one third of a leaf were simulated for one-year old silver birch (Betula pendula Roth) seedlings once, at the beginning of the vegetation season. The height, aboveground and root biomass, root length, stem diameter and leaf area were measured for all damaged and control seedlings. The aim of the study was to examine the effects of different insect-damage simulations on silver birch growth. Our study demonstrated that leaf dry mass decreased in response to leaf perforations and clipping one third of leaf. However, at the end of the experiment, the cumulative dry mass reached the level of the control. We found no statistically significant effect on the aboveground and total biomass of damaged seedlings compared to the control. The leaf clipping decreased the leaf area and stem diameter compared both to the treatment with hole-damaged seedlings and the control. The induced birch growth response showed that tree seedlings were able to compensate their growth up to the control level after the insect damage in eight weeks.

Urban trees, integral to urban environments, demonstrate intricate responses to atmospheric pollutants like particulate matter (PM), tropospheric ozone (O₃), and carbon dioxide (CO₂). Notably, O₃ induces oxidative stress in leaf tissues, while PM, consisting of fine airborne particles, interacts with urban trees through foliar deposition. This interaction is particularly interesting as tree canopies are highly effective filters, capturing and accumulating PM on their surfaces. The present study focused on silver birch, small-leaved lime, and Norway maple seedlings responses to elevated O₃ and CO₂). With and without PM. Maple seedlings exhibited the highest stem height increment, followed by lime and birch. Elevated O₃ and CO₂ without PM led to substantial height increments for lime and maple. Elevated O₃ and CO₂ without PM increased the total polyphenols in lime and maple leaves but decreased the content of total flavonoids in birch and lime leaves. Our findings underscore the adaptability of lime and maple seedlings to elevated O₃ and CO₂, positioning them as promising species for urban environments in the face of changing climates. Birch, while exhibiting biochemical changes, demonstrated less pronounced growth responses. This studyʼs insights into the intricate interactions between urban trees and multiple pollutants, particularly the species-specific responses, are of significant value for urban planning and environmental management.