• Height increment-climate relationships of Scots pine were assessed using dendrochronological techniques.• Annual height increment was significantly affected by climatic factors.• In western Latvia, temperature in preceding summer mainly affected height increment.• In eastern Latvia height increment was affected by previous autumn temperature.• During the 20th century, the effect of climatic factors has altered likely dues to climate change. AbstractHeight growth of trees is a crucial parameter that influences the composition and productivity of forest stands and quality of timber; however, the relationships between annual height increment (HI) and climatic factors have been poorly studied. In this study, the effect of monthly mean temperature and precipitation sums on the HI of Scots pine in two sites in Latvia have been determined using dendrochronological techniques. Correlation and response function analyses were conducted for entire chronologies of HI and for 50-year intervals within them. Climatic factors significantly affected the HI of Scots pine; however, not only did the suite of significant factors differ between the sites, but the influence of these factors changed during the 20th century. In the site in western Latvia where climate is milder, temperature in the preceding summer was the main climatic determinant of HI. The effect of temperature in the dormant period and spring was significant during the first part of the 20th century, while the effect of temperature in the previous September and November has become significant since the second half of the 20th century. In the site in eastern Latvia where summers are hotter, HI has been affected by both temperature and water deficit related factors in the summer. However, since the later part of the 20th century, the effect of temperature in the previous October has intensified and become the main climatic determinant of HI.
Abstract. With the increasing demand for renewable energy in the domestic market, additional attention is paid to the use of stump-wood in energy supply. The stump harvesting technology is not substantiated sufficiently so that the end users can use this unpredictable raw material to generate heat and power. Service providing logging companies need to know the specific requirements to equipment and the characteristics of stump harvesting technologies in order to assess the possibility of acquiring this natural resource. The stump harvesting should be planned along with the regenerative felling, because the layout of the timber forwarding roads and the characteristic of the logging residues layer on the road surface are important. In its turn, when planning the upper timber yard, it is necessary to take into account the meteorological data, the prevailing wind direction and water streams. The aim of the study is to find out the total energy balance during the stump extraction with the MCR500 bucket. Working time, output volumes and productivity indicators are derived from the project "Development and testing of a prototype of multifunctional equipment for stump-wood production and preparation of the soil mounds" (2DP/2.1.1.1.0/10/APIA/VIAA/174) results and from the results of the joint stock company "Latvia state forest" project implemented in 2008. The most energy-consuming process is comminution of biomass, therefore it is common, for instance, in Finland that electricity-operated equipment located near the customer is used to carry out this work. More efficient use of forest resources by stump extraction and further utilization in heat and power production can increase biomass deliveries for energy applications by 500 thousand tons of dry matter of currently unused coniferous stump biomass annually.
European beech (Fagus sylvatica L.) timber value is high in southern Europe due to a great demand from Asia. Since the timber market is global, over a long time we can expect gradual increase in demand also in other countries, including Latvia, where climatic conditions becomes increasingly more suitable for this species due to ongoing climatic changes. In order to develop recommendation for the use of beech in our country, the aim of the study was to assess the potential financial gain from Fagus sylvatica stands in Latvia. Assortment structure, defined by topdiameter and length, as well as their prices was set based on the literature survey. Results showed higher income from older (115 years) than form younger (58 years) stands: 9108 EUR ha -1 , and 7939 EUR ha -1 , respectively. However, the opposite was true for the net present value (r = 3%): 1423 EUR ha -1 and 304 EUR ha -1 , respectively.
Biomass as a source of renewable energy is gaining an increasing importance in the context of emission targets set by the European Union. Large areas of abandoned agricultural land with different soils are potentially available for establishment of biomass plantations in the Baltic states. Considering soil and climatic requirements as well as traits characteristic for lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm) and the scarcity of published knowledge, we assessed the above-ground biomass of Pinus contorta in comparison to that of native Scots pine (Pinus sylvestris L.) and factors affecting biomass production. Data were collected in 3 experimental trials, located in two sites in central part of Latvia: Zvirgzde and Kuldiga (56°41’ N, 24°28’ E and 57°03’ N, 21°57’ E, respectively). Trials were established with density 5000 tree ha-1, using seed material from Canada (50°08’-60°15’ N, 116°25’-132°50’ W) and two Pinus contorta stands with unknown origin growing in Latvia. Results reveal that absolute dry aboveground biomass of Pinus contorta reaches 114 ± 6.4 t ha-1 at age 16 on a fertile former arable land, 48 ± 3.6 and 94 ± 9.4 t ha-1 at age 22 and 25, respectively, on a sandy forest land (Vacciniosa forest type). The biomass is significantly (p < 0.01) and considerably (more than two-fold) higher than that of the native Pinus sylvestris and the productivity is similar (in fertile soils) or higher (on poor soils) than reported for other species in energy-wood plantations. Provenance was a significant factor affecting the above-ground biomass, and the ranking of provenances did not change significantly between different soil conditions. It provides opportunities for further improvement of productivity using selection
Nowadays, work is becoming more dynamic; requiring great attention, maximizing the mental and physical abilities of the worker who suffers poor health as a consequence. It is essential for the employer to determine in a timely manner whether workplace risks cause adverse effects on employees' health and whether the labour protection specialist is fit for the job to be performed. A high quality master program promotes students' preparedness to meet economic sector requirements, and ensures long-term work and life environment sustainability. This is accompanied by mandatory health screenings intended to identify health problems in a timely manner. The tasks of the labour protection specialist are to find regulations to support the primacy of effective and high quality mandatory health screenings, to reduce the incidence of perfunctorily compliant attitudes among employees to health protection, and to promote long-term quality of life. The study was conducted using questionnaires (418 respondents) and expert interviews. The IBM SPSS 23 (Statistical Package for the Social Sciences) was used for analysis of the data generated by the employee survey. It has been found that the effectiveness of mandatory health screenings is intrinsically connected to their quality. The more competent, conscientious and honest is each participant in this activity -the employer, occupational physician and employee -the more effective is the mandatory health screening. The study identified the need to increase the competence of labour protection specialists by improving the master program to ensure the necessary raising of awareness in the context of mandatory health screening.
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