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Post-storm regeneration of Norway spruce Texto completo
2019
Snepsts, G., Latvian State Forest Research Inst. Silava, Salaspils (Latvia); Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Donis, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Strelnieks, K., MVR LUX, SIA, Riga (Latvia) | Krisans, O., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Desaine, I., Skogssallskapet, SIA, Riga (Latvia) | Adamovics, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Impact of abiotic (wind, summer drought) and secondary (bark beetle (Scolytinae)) or primary (cervids (Cervidae)) biotic factors affect the survival of Norway spruce (Picea abies (L.) Karst.) that is an economically important tree species. Norway spruce is mostly regenerated via planting – thus with significant investment. Therefore it is important to improve the resistance of Norway spruce stands as much as possible. Aim of the study was to characterize damages in Norway spruce stands by cyclonic wind storm and the regeneration of the stands, destroyed by the storm. Data from 4491 Norway spruce dominated stand, destroyed by the storm of 2005, from State Forest service database were obtained. Areas of post-storm sanitary clearcuts ranged from 0.1 to 7.6, mean 0.9 ± 0.02 ha. Most of the clearcuts were larger than 0.5 ha, demonstrating a relatively large size of gaps created by this natural disturbance. Changes of dominant trees species after the storm were statistically significantly affected by the forest type and type of regeneration. Overall, it happened in 55% of the former Norway spruce areas and was predominantly in cases, where natural regeneration was practiced. No indications of measures to increase stability of future stands against wind damages were found.
Mostrar más [+] Menos [-]The exhaustion of water resources in the Kuyavian-Pomeranian Voivodship in drought conditions in 2015 Texto completo
2019
Solarczyk, A., Nicolaus Copernicus Univ. in Torun (Poland) | Kubiak-Wojcicka, K., Nicolaus Copernicus Univ. in Torun (Poland)
The aim of the paper is to present the spatial diversity of water resources in the Kuyavian-Pomeranian Voivodship during the drought in 2015. The region’s area is characterized by the lowest average annual precipitation in Poland, the lowest water resources and high water demand associated with intensive plant production. Hydrological research was carried out in September 2015 in 145 measurement points on various rivers. Despite the low precipitation recorded in August 2015 at the majority of meteorological stations, the volume of the specific discharge from the Kuyavian-Pomeranian region was characterized by high variability. The largest specific discharges were recorded for rivers located in the northern part of the region whose sources are located in the Pomeranian Lake District, i.e. Brda and Wda (over 2 dm3 sE−1 kmE−2) and the Masurian Lake District (Drwęca over 1 dm3 sE−1 km E−2). The smallest specific discharges (less than 0.5 dm3 sE−1 kmE−2) were recorded in the catchments located in the Kuyavian region (Tążyna, Zgłowiączka and Noteć) in the southern part of the Kuyavian-Pomeranian Voivodship and from the Osa River catchment. These areas are intensively used for agricultural purposes. The use of surface water resources as a potential source of irrigation water for crops can only be taken into account in connection with groundwater resources.
Mostrar más [+] Menos [-]Urban hydrology research fundamentals for waste management practices Texto completo
2019
Pehme, K.-M., Estonian Univ. of Life Sciences, Tartu (Estonia) | Burlakovs, J., Estonian Univ. of Life Sciences, Tartu (Estonia);Linnaeus Univ. (Sweden);University of Latvia, Riga (Latvia) | Kriipsalu, M., Estonian Univ. of Life Sciences, Tartu (Estonia);University of Latvia, Riga (Latvia) | Pilecka, J., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Grinfelde, I. [and three others], Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
The urbanization and increasing growth of planet’s population accumulates significant volume of disposed waste as well as increases risks on human health and environmental safety. Landfill systems are the dynamic, living in space and time, potentially harmful entities that must be managed in as careful and smart way as possible. There are many studies related to landfill emissions such as leachates and methane. However, there is a need for advanced understanding of landfill hydrological regime and risks related to climate change and associated changes of hydrological cycle. The comprehensive studies about the urban hydrology are available; however, application to landfill management is fragmentary and inconsistent in several aspects. Landfill in long term has an impact on hydrological cycle. The heterogeneous land surface is one of aspects; however, there are still unanswered questions about the urban environment impact on water balance components. The aim of this study is to describe fundamentals of landfill hydrology in urban hydrological response unit context as well as evaluate the potential risks to environment and human health related to landfill geomorphology and hydrological balance in temporal climate conditions. The landfill hydrological cycle has similarities with urban hydrological cycle; however, there are additional components related to landfill specification, e.g., irrigation or leachate recirculation as well as total produced leachate.
Mostrar más [+] Menos [-]Behaviour of timber portal frame depending on rotational stiffness of knee joint Texto completo
2019
Fabriciuss, J., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Ozola, L., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
In this article, the topic under discussion is the development of deformations in semi-rigid knee joints made of dowel type fasteners and consequences expected regarding overall deformations of timber portal frame structure. The use of semi-rigid connection resolves the problem of transportation, but development of small rotation in connection reduces the stiffness of the connection that becomes significant during service life. It is assumed that the rotational stiffness modulus Kφ (kNm∙radE−1) is the relevant characteristic of semi-rigid connection. Timber portal frame structure (span 30 m) designed with dowel type fasteners located around two circles has been subjected to different loading trials by using Dlubal software (RFEM). Results of a numerical study of portal frame model demonstrate the importance of characteristics of semi-rigid knee joints for design. It is found that developing deformations in the semi-rigid knee connection produce up to 90% bigger vertical displacement at an apex point and 96% bigger horizontal displacement comparing with the rigid knee joint model.
Mostrar más [+] Menos [-]Assessment of land use change scenario to increase primary productivity function at local scale Texto completo
2019
Valujeva, K., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia);Wageningen Univ. and Research (Netherlands) | Nipers, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Lupikis, A., Latvian State Forest Research Inst. Silava, Salaspils, Latvia | Pilecka, J., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Schulte, R.P.O., Wageningen Univ. and Research (Netherlands)
The global population has begun to rise exponentially; therefore, the demand for bioresources including food and fibre is increasing. An increasing demand for food and fibre necessitates more sustainable use of natural resources especially for soilbased ecosystem services. In this context, Functional Land Management was developed to optimize agricultural soilbased ecosystem services to meet both agricultural and environmental targets simultaneously. The aim of the research is to evaluate unmanaged agricultural land use change impact on primary productivity function in three parishes in Latvia by using Functional Land Management framework. Evaluation of primary productivity function was accomplished for both sectors agriculture and forestry by using profit and working hours as a proxyindicators. Production of vegetables and perennial plantations has higher supply of primary productivity function comparing to other land uses. Land use changes affect all soil functions that we expect from our land, especially primary productivity function. After applying land use changes, an increase in profit is higher in Liezere parish for both areas on mineral soils (7.1%) and areas on organic soils (5.2%); while an increase in working hours is higher in Usma parish: 36.6% in areas on mineral soils and 1.0% increase in areas on organic soils. Shortterm benefits are received from agricultural land, while forest land provides long-term return which increases over time but can only be obtained after reaching the age of felling. Before applying land use changes or changes in management practices we have to consider other soil function and national commitments.
Mostrar más [+] Menos [-]Review of cooling solutions for compact electronic devices Texto completo
2019
Galins, J., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Laizans, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Galins, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
Nowadays, with the rapid development of robotics and automation, there is a need for more powerful, more compact data processing equipment that also emits more heat. Various electronics cooling solutions are already in use, others are in development. Each cooling solution has its advantages and disadvantages. Active cooling usually dissipates heat more efficiently, but passive cooling is more reliable, especially when the electrical system is exposed to aggressive environmental influences. The possibility of using graphene in the manufacture of electrical equipment components is widely studied. Graphene could significantly improve the efficiency of passive cooling because its thermal conductivity is much better than copper.
Mostrar más [+] Menos [-]Effect of salt treatment on yield and quality of frozen cod loins Texto completo
2019
Liorancas, V., Klaipeda State Univ. of Applied Sciences (Lithuania)
Study has been performed in fish processing plant ‘X’ with an aim of on purpose to investigating the influence of salt treatment on yield and quality of frozen cod loins. Samples were soaked in 0.8, 1.2, 10% NaCl concentrations in brine before being frozen. In this study, the cod loin’s weight loss during refrigeration, defrosting and cooking was calculated and sensory analysis was carried out. It was found that the soaking in brines affected higher weight of cod loins after freezing. In the control group it decreased by 1.14%, but the S0.8, S1.2 and S10 groups had the weight gain, respectively 3.41, 4.72 and +4.78%. Although after the defrosting and cooking the control group had the lowest weight losses, considering the losses of all operations, it was found that the largest weight loss was in the control group and in the S0.8 group, respectively 31.19% and 31.29%, while the lowest in the S1.2 and S10 groups – 30.49 and 30.06% (p is less than 0.05), respectively. Salt treatment did not affect the taste and odour, but improved the cod loin’s texture properties. Based on these results, salt treatment is considered as an effective way to improve the yield and quality of frozen cod loins.
Mostrar más [+] Menos [-]Isolation of cellulolytic bacterial strains from Rangifer tarandus rumen microflora Texto completo
2019
Dubrovin, A., BIOTROF+, OOO, St. Petersburg (Russian Federation) | Dunyashev, T., BIOTROF+, OOO, St. Petersburg (Russian Federation) | Ilina, L., BIOTROF+, OOO, St. Petersburg (Russian Federation) | Filippova, V., BIOTROF+, OOO, St. Petersburg (Russian Federation) | Laishev, K., North-West Centre for Interdisciplinary Research on Food Security Problems, Saint Petersburg (Russian Federation)
The feature of the microorganisms of rumen microbiocenosis is the ability to form a number of digestive enzymes, including cellulases, which allows ruminants use the energy of feeds rich in fiber. Microorganisms that are promising as a source of cellulases, biodestructors of toxins having antagonistic properties against pathogens for creating probiotic feed additives, both for reindeer and for other livestock, were isolated from the reindeer rumen. The aim of the study was to create a collection of microorganisms that are promising for creating a biopreparation. As a result, collections of 63 associations of microorganisms decomposing cellulose and carboxymethylcellulose were created; their morphology and cultural properties were described. It was found that the amount of cellulose degradation was 44 – 62% in the 4 most active isolates (No 14, 15, 21 and 26). The obtained data allowed to make a conclusion about the ability of bacterial strains isolated from the rumen to synthesize cellulolytic enzymes carrying out cellulose biodegradation, which allows them to gain a competitive advantage in the rumen of the reindeer diets with an abundance of cellulose. Isolates No 14 and 15 showed high antagonistic activity to Fusarium sporotrichioides, and isolate No 15 and 16 showed high antagonistic activity to Fusarium oxysporum. Isolate No 15 showed a wider antifungal activity compared to other isolates. Among all isolated strains, this bacterial isolate is represented as having a large spectrum of activities, including both high cellulolytic and high antifingal activity.
Mostrar más [+] Menos [-]Above-ground and seed bank weed biodiversity comparison in conventional and organic farming systems in Poland Texto completo
2019
Berbec, A.K., Institute of Soil Science and Plant Cultivation, State Research Inst., Pulawy (Poland) | Feledyn-Szewczyk , B., Institute of Soil Science and Plant Cultivation, State Research Inst., Pulawy
The assessment and conservation of agricultural biodiversity is one of the current goals of European Union policies, which are reflected in European Biodiversity Strategy. The biodiversity of soil seed bank and above-ground weed flora were investigated in spring cereals in organic and conventional farming system. The study was carried out between 2012 and 2014. Species of above-ground wild flora were counted on a surface of 1 square m in the field. Soil for seed bank evaluation was taken from the field and evaluated by seedling emergence method in a greenhouse. There were no significant differences in number of species between two communities. Biodiversity of weed community, described by Shannon’s diversity index and Simpson’s dominance index, was significantly better maintained in the soil seed bank than in above-ground flora in both farming systems. A strong, positive correlation between the number of species, Shannon’s diversity index, Simpson’s dominance index of soil seed bank and above-ground weed species was found in both farming systems, while abundance of seeds and above-ground weeds was significantly, positively correlated only in the conventional farming system. Qualitative composition of weed flora depended more on the type of community (soil seed bank or above-ground weed communities) than the farming system.
Mostrar más [+] Menos [-]Assessment of spring barley populations in comparison to homogenous varieties Texto completo
2019
Locmele, I., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia);Latvia Univ. of Life Sciences and Technologies, Priekuli, Priekuli Parish, Priekuli Municipality (Latvia). Inst. of Agricultural Resources and Economics | Legzdina, L., Latvia Univ. of Life Sciences and Technologies, Priekuli, Priekuli Parish, Priekuli Municipality (Latvia). Inst. of Agricultural Resources and Economics | Piliksere, D., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Gaile, Z., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Kronberga, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia);Latvia Univ. of Life Sciences and Technologies, Priekuli, Priekuli Parish, Priekuli Municipality (Latvia). Inst. of Agricultural Resources and Economics
The necessity to increase genetic diversity in agriculture has been widely discussed during the last decades. Heterogeneous populations are one of the ways to increase genetic diversity in varieties of self-pollinating cereals. The aim of this research was to compare grain yield, its stability, foliar diseases severity and competitiveness against the weeds of spring barley (Hordeum vulgare) populations and homogenous varieties. Field trials consisting of three types of populations (simple, complex and composite cross populations – CCP) containing different levels of diversity and three check varieties were carried out during 2015−2018 under organic and conventional farming systems. No one of the populations had a significantly higher average yield than any of the check varieties. CCP1 showed a tendency to be more productive under organic growing conditions and can be characterized as widely adaptable to various growing conditions with a significantly higher yield as the average overall environments. One of the complex populations showed adaptability to favourable growing conditions and yield insignificantly higher than overall average. Other studied populations can be characterized with wide adaptability and various yield levels. For most of the populations under organic and conventional conditions, a significantly lower net blotch (caused by Pyrenophora teres) severity was observed in comparison with the most susceptible variety; infection with powdery mildew (caused by Blumeria graminis) lower than for check varieties was observed under organic growing conditions, whereas such trend was not observed under conventional conditions. All populations had a significantly lower crop ground cover and slightly lower competiveness against weeds than the variety with the best competitiveness
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