The article discusses the importance of small hydro power plants in the Polish power system and defines the legal conditions for the operation of small hydro power plants. The phenomena occurring in the hydrological system of small hydro power plants and their impact on the natural environment were analyzed. An analysis of phenomena occurring in the hydrological system and the activity of small hydro power plants that are operating on the Radunia River helped us identify relations between different types of power plants working in cascades and possibilities of power generation control in period of several days. The above-mentioned analysis has been used in the development of a mathematical model of a hydroelectric plant and cascades of hydroelectric plants. The numerical simulations carried out concerned both the self-operating power plant and a cascade of two identical objects of this type. There is a possibility for small hydro power plant to run as a base load power plant and during periods of high demand as well (peak demand or unexpected loss of generation in the power system). A single hydroelectric power plant can deal with varying peak load demands while adding a second stage increase those abilities. A cascade of reservoir hydropower plants has a much greater ability to store energy and give it back in time. In addition, the existence of a second power plant equipped with a surge reservoir allows for a significant reduction in the amplitude of flows in the river below the cascade, which will reduce the negative impact of the cascade on the environment.

This article presents the results of studies assesing the significance of the most important macro- and microeconomic factors affecting investors’ propensity to invest in mining. The Polish mining industry in recent years has seen intensive restructuring processes which have considerably affected the status of fixed assets required for the exploitation of useful minerals. In order to efectively manage technological progress in mining plants, it is necessary to understand the role of individual, variable factors influencing investors’ propensity tomake specific expenditures. In the analysis, mathematical statistics and econometric modelling methods were applied to determine the nature of correlations between the values studied and their significance. This examination applied statistical data accumulated by economic entities from 2000–2010. A linear econometric model waspresented illustrating the relationship between capital expenditure in mining and such indicators as fixed assetsvalue, GDP, real interest rate, consumption levels of fixed asset components in mining, and various other factors. Structural parameters of a function specifying the level of investment expenditure can be determined based on statistical data which has been appropriately processed so that the model constructed reflects the economic process studied in relevant way.

Such a model is not free of defects typical in statistical models; however, it simultaneously enables one toobtain valuable information concerning the impact of the factors studied on the value of such expenditure, and the theoretical possibilities to exchange the specific quantity of one factor for another factor. In the final version of the model, it is often sufficient to include only these independent variables which contribute the most essential information to the independent variable. This often simplifies the final form of the model without simultaneous limiting of its importance in explaining the economic phenomenon studied and the possibilities of its practical application. In the final selection of significant variables captured in the model, the method of information capacity indicators was used.

The energy obtained from biomass in the global balance of energy carriers is the largest source among all RES. It should be borne in mind that the share of biomass as an energy carrier in the total balance is as much as 14%. The basic sources of renewable energy used in Poland are the wind power industry and biomass. Organic chemical compounds are the source of chemical energy for biomass. The biomass can be used in a solid form (wood, straw) or after being converted to liquid (alcohol, bio-oil) or gas (biogas) form.

Pellets, meaning, the type of fuel of natural origin created from biomass compressed under high pressure without the participation of any chemical adhesive substances are recognized as the most common and available grades of biomass. Wood pellets manufactured from sawdust, shaving, or woodchips are the most popular type of pellets on the market. Fuel created in the form of granules is very dense and can be manufactured with low humidity content, which translates into an exceptionally high burn efficiency.

The authors of this article burned agro pellets from Miscanthus giganteus without additives and with solid catalyst and conducted a series of tests that determine the impact of boiler settings (blast power, time of feeding, chimney draft) on the process of burning fuel in real conditions. A solid catalyst was used to improve combustion conditions in one of the fuels. The catalyst burns carbon monoxide and reduces nitrogen oxides. The results in the form of observation of selected parameters are summarized in the table.

The mining sector played an important role in the economic growth of the developed countries with rich natural resources in the past, and in recent years, it is important for the economic growth of developing countries. Also, it is generally supported by the incentives due to the fact that mining sector causes other related sectors to grow. Incentives have been the most important economic policy instrument imposed by governments to boost economic growth in developed and developing countries. Incentives or supports given by Turkish state in order to increase the mining investments can be analyzed under two categories; incentives or supports based on the Turkish Mining Law, incentives or supports provided under the Investment Incentive Program. The effect of investment incentives applied to the mining sector in Turkey between the years of 2001 and 2017 on mining production index (MPI) and also the indirect effect of these on gross domestic product (GDP) are investigated by using Granger Causality Test and regression analysis. In this study, the data belonging to the number of investment incentive certificates received by firms operating in Mining Sector and the amount of total fixed investment were used. According to the findings obtained from this study, it has been determined that encouraging the fixed investments of the firms operating in the Mining Sector with incentives has a significant and positive impact on MPI and GDP in a short period of 1 year. H owever, the incentives applied to the mining sector did not increase the production index of the mine in parallel with the increase in the GDP.

The rose flea beetle, RFB (Luperomorpha xanthodera Fairmaire 1888) is a new flower pest in Europe. In 2012, it was brought accidentally to central Poland. To search for this introduced species in the area adjacent to the site of the first finding, 29 plant species belonging to five botanical families (Lamiaceae, Brassicaceae, Asteraceae, Plantaginaceae, Crassulaceae) were monitored over a 3-year-long study (2016−2018). RFB were found on 11 herbaceous/ ornamental plant species (Lamiaceae, Brassicaceae, Asteraceae) along with feeding damage to the flowers. White mustard (Sinapis alba L., Brassicaceae), hyssop (L.), and Monarda spp. (Lamiaceae) were its most preferred host plants. In each season, RFB females preferred host plants which bloomed abundantly and vividly. However, among the examined plant species there was a large variation in the year-to-year RFB abundance. Over the examined period the RFB extended its abundance exponentially, and its population survived and established itself in the area. The general sex ratio of the beetles was strongly female biased. In the female pool, females with conspicuously swollen abdomens predominated. The results of our study provide more insight into RFB behaviour, its establishment and spreading into new areas. To support the evidence for the RFB risk factor as an agricultural/ horticultural pest, further research should focus on the beetles’ biology, reproductive tactics, larval host plant preference, larva-inflicted damage and harmfulness, the impact of the RFB on the native fauna, as well as its further local and distant migration propensity. Presently our knowledge about these aspects is still fragmentary.

Recent decades have witnessed a shift in the balance of nitrogen circulation processes in ecosystems. What does this mean for our forests, our atmosphere and the planet as a whole?

Rice blast is the main disease of rice plants in Indonesia and several countries worldwide. Controlling this disease using chemical fungicides has harmful effects on the environment. Therefore, we need biocontrol agents which are more environmentally friendly such as rice phyllosphere bacteria. This study aimed to explore bacteria producing bioactive compounds from the rice phyllosphere environment to control blast disease. A total of 88 isolates were successfully isolated from rice leaves in Sukabumi, Situgede, and Jasinga (West Java, Indonesia). From them, we obtained 22 bacteria isolates with antifungal activity against Pyricularia oryzae in vitro assay. In addition, seven non-pathogenic bacteria were obtained from further screening in hypersensitivity, hemolysis and pathogenicity assays, namely STGG 3, STGG 7, STGG 8, STGG 14, SKBV 1, STGV 8, and SKBG 78. To show their antifungal activity, we tested crude extracts of these seven isolates and the results revealed that all the crude extracts can inhibit the growth of P. oryzae. Based on a genetic approach, isolates STGG 3, STGG 7, and STGG 14 were found to have both nonribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) genes, while isolate SKBV 1 only had the NRPS gene. The NRPS and PKS genes from potential isolates were similar to NRPS and PKS genes of Bacillus sp. in different strains. Furthermore, molecular identification based on the 16S rRNA gene revealed that the seven potential isolates belong to three genera, i.e. Bacillus (STGG 3, STGG 7, STGG 8, STGG 14, SKBV 1), Enterobacter (STGV 8) and Brachybacterium (SKBG 78). We suggest that the seven isolates found in this study have potency and could be recommended as biocontrol agents of blast disease caused by P. oryzae.

Almost half (47%) of Latvian forest areas (3611 thousand ha) are considered degraded or partly improved by the hydro-technical drainage. The degradation is caused by very poor soil aeration due to waterlogged conditions. The location of waterlogged forests in Latvia is neither uniform nor occasional. Comparison of the abundance of waterlogged forests and the amount of atmospheric precipitation showed that the waterlogged forests are mainly located in areas with least precipitation. This hydrological phenomenon is connected with water discharge in drainage ditches: even during the dry summers of the years 1963, 1964, 1975, 1976 and 2002 in the drained forests with deep peat soils water flowed continuously in 1 m deep ditches and the discharge exceeded the amount of precipitation. Using the data from 182 sample plots in drained forests with the peat layer depth of 4.2 m, it was found, that coniferous forests are most productive in areas where the peat layer is most dense. One of the possible explanations for this phenomenon is that the most intensive paludification and formation of most dense peat layer are characteristic for the areas with intensive water discharge from confined aquifers. This discharge provides necessary mineral nutrients for the forest soil regardless of the peat layer thickness. The forest productivity may increase several times due to the enhancement of water movement in soil and to improved soil aeration by hydro-technical drainage. Also the flow regime of rivers connected with the drained areas changes considerably, mitigating extremely high and low flow events.