Fulltext search in archive
Results 241 to 270 of 271:
Findings regarding ectotrophic stability of Norway spruce forest of the Krkonoše and Orlické Mountains based on mycorrhiza studiesV. Pešková, J. Landa, F. SoukupJ. For. Sci., 2011, 57(11):500-513 | DOI: 10.17221/139/2010-JFS Analyses of root mycorrhizal samples and monitoring of fruiting bodies of macromycetes from Norway spruce stands at mountain and foothill localities in the Krkonoše and Orlické Mts. provided several data series allowing to assess and compare (albeit somewhat preliminarily) mycorrhizal conditions and macromycete incidence related to stand ages and location conditions. The overall mycorrhizal conditions in young (10 years old) and older (80 years old) stands on formerly agricultural soils are comparable to those in 80- and 90-year-old forests growing on standard forest soils, but young spruce stands in the Orlické Mts. replanted on forest soils do not surprisingly show any favourable mycorrhizal characteristics. The research documents a marked diversity of macromycete species composition in mountain spruce stands compared to foothill spruce stands on former agricultural soils. While in the younger mountain spruce stands of the Orlické Mts. the expansion of macromycete species composition began to develop in a similar fashion to that in the Krkonoše Mts., the comparison of older (80-year-old) stands on formerly agricultural soils in the Orlické Mts. foothills and Krkonoše Mts. implies that the macromycete species composition developed quite differently but with a similar success. |
Rationalization of the performance of a mobile off-road system working in the forest environment with respect to its emission loadA. Janeček, A. Skoupý, R. KlvačJ. For. Sci., 2008, 54(3):125-130 | DOI: 10.17221/3098-JFS This paper deals with the possibilities of minimizing the emissions of heterogeneous substances/pollutants (SO2, NOx and NCx) per volume unit of processed timber, based on measurements of the design and operating performance of a mobile off-road system working in the forest environment. The forest production system is taken to mean the production system into which the material and resource flow and/or even the workforce flow enter. During the production process the material, power and/or workforce flow is transformed into the final product (processed timber, soil preparation, afforestation, etc.). Operating and/or design capacity is the control variable optimizing the operating mode of the forest production system. The quantities of emitted pollutants related to the work unit done by the production system represent the criterional function specifying the optimization of parameters of the mobile off-road system working in the forest sector. The conditions for the operating mode (performance) of the mobile off-road system working in the forest environment under which the minimum emitted pollutants related to the unit of done work are reached have been determined. The theoretical conclusions have been verified experimentally. |
The extent of root rot damage in Norway spruce stands established on fertile sites of former agricultural landR. MarešJ. For. Sci., 2010, 56(1):1-6 | DOI: 10.17221/36/2009-JFS The aim of this study was to compare the degree of root rot damage in two large complexes of Norway spruce stands established on former agricultural land at fertile sites. The root rot infection was observed on the stump cutting area on both intended and salvage clear fellings. Stands in Kružberk area in the Nízký Jeseník Mts. established on arable land showed very poor stability and large root rot damage at the age of 40-50 years. In contrast, stands in Lužná area in the Javorníky Mts., founded on former sheep pastures, were markedly much less damaged at the age of 90-110 years and proved to be able to provide quality timber, although they were damaged by the root rot as well. |
Status of an indigenous agro-forestry system in changing climate: A case study of the middle Himalayan region of Tehri Garhwal, IndiaC. P. KalaJ. For. Sci., 2010, 56(8):373-380 | DOI: 10.17221/113/2009-JFS The agro-forestry system is one of the best known indigenous practices for livelihood. In view of instant decline in the rainfed hill agro-forestry system the present study was undertaken in the hilly villages of Uttarakhand state of India with the major objective to assess the status and effects of various factors on this centuries old indigenous agro-forestry system. The survey documented a total of 26 herbaceous food crop species and 21 woody species that were raised by farmers in the selected villages of Uttarakhand. A total of 37 plant species available in the agro-forestry system and used for curing various ailments by traditional healers were also documented during the survey. The major cereals produced by farmers were Oryza sativa L., Echinochloa frumentoacea Link., Eleusine coracana (L.) Gaertner and Triticum aestivum L. The indigenous system of cropping was locally called as Baranaja that revolved around the production of > 12 varieties of crops. Besides food, the species grown in the agro-forestry system were used for multiple purposes. Water scarcity, migration of youth in search of employment and changing socio-economic and climatic conditions were some of the major reasons for declining agro-forestry system and abandoning the agricultural land. |
Development of foliage biomass of young spruce and beech stands in the mountain water balance research areaP. Kantor, F. Šach, V. ČernohousJ. For. Sci., 2009, 55(2):51-62 | DOI: 10.17221/72/2008-JFS The investigation of foliage biomass development including LAI and the growth of spruce and beech stands in the juvenile stage (age 1 to 21 years) represents a special complementary study to long-term research of water balance components on the experimental forest hydrology area Deštné Mountainside. The experiment is located in the Orlické hory Mts. at the altitude of 900 m on a clear-felled area. In 1982 the spruce plantation was established at 1.5 ´ 1.5 m spacing (4,600 plants/ha) and the beech plantation at 1.0 ´ 1.0 m (10,000 plants/ha). According to tending programs applicable to forest stands in the Czech Republic, two improvement fellings were carried out (1995 and 2001) in spruce and none in beech. In 2002, some 1,550 spruce trees/ha (mean height 10.1 m) and 7,440 beech trees/ha (mean height 4.8 m) were recorded. At the end of the first vegetation season in 1982, the dry matter (DM) of foliage in spruce and beech amounted to 35 and 70 kg/ha, respectively. Five years later (1987), these values increased to 770 and 360 kg/ha in spruce and beech, respectively. At a stand age of 21 years, foliage DM was determined to be 11,940 kg/ha for spruce and 3,050 kg/ha for beech. At the same time, the leaf-area index (LAI) was calculated to be 5.55 and 5.94 in spruce and beech, respectively. The method of foliage biomass quantification, based on the determination of foliage DM of mean sample trees and stand density, enabled to acquire complementary data usable in long-term research of the water regime of spruce and beech and simultaneously to provide information on the potential of biomass production and LAI value of both main commercial species in mountain forests of the Czech Republic. |
Comparison of mycobiota of diverse aged spruce stands on former agricultural soilV. Pešková, F. Soukup, J. LandaJ. For. Sci., 2009, 55(10):452-460 | DOI: 10.17221/3/2009-JFS The mycological conditions on study plots established in forests growing on former agricultural farm lands were studied. In young spruce stand (8-10 years) reduced and unstable spectrum of macromycetes was found. After approximately 50 years of forest growth the situation became stable and spectrum of macromycetes together with development of mycorrhizal status were similar to a situation found in stands on forest soils. Slightly increased occurrence of saproparasitic species of fungi (e.g. Heterobasidion annosum at others) was observed in older growths. |
Quantity and distribution of fine root biomass in the intermediate stage of beech virgin forest Badínsky pralesP. Jaloviar, L. Bakošová, S. Kucbel, J. VencurikJ. For. Sci., 2009, 55(11):502-510 | DOI: 10.17221/31/2009-JFS The fine root biomass represents 3,372 kg/ha in the intermediate stage of the beech virgin forest with different admixture of goat willow, where the vast majority of this biomass is located in the uppermost mineral soil layer 0-10 cm. The variability of the fine root biomass calculated from 35 sample points represents approximately 90% of the mean value and reaches the highest value within the humus layer. The total fine root length investigated in 10 cm thick soil layers decreases with increasing soil depth. A significant linear relationship between the fine root length (calculated per 1 cm thick soil layer and 1 m2 of stand area) and the soil depth was confirmed, although the correlation is rather weak. The number of root tips decreases with increasing soil depth faster than the root length. As the number of tips per 1 cm of root length remains in the finest diameter class without significant changes, the reason is above all a decreased proportion of the finest root class (diameter up to 0.5 mm) from the total fine root length within the particular soil layer. |
Multifunctional forestry practices as a land use strategy to meet increasing private and public demands in modern societiesF. SchmithüsenJ. For. Sci., 2007, 53(6):290-298 | DOI: 10.17221/2016-JFS The present distribution of forests and the degree of their transformation by man are the results of natural factors and cultural development. The limit between forested areas and open spaces, as well as differences between intensively used forests and those showing small or no traces of human intervention, is determined by social needs and values, economic opportunities, and political regulations. Forests are currently perceived by the population as physical and social spaces profoundly influenced by timber use and forest management. Their social and political significance is in full evolution. The multiple demands on forests in a rapidly evolving economic, social, and political environment require maintaining a high level of forest management standards and a flexible adaptation of multiple-use forestry to the complex interactions between the private and public sectors. |
An estimation of willingness to pay for asparagus (Asparagus racemosus Willd.) collectors in Makawanpur District, NepalT. N. Maraseni, J. Maroulis, G. CockfieldJ. For. Sci., 2008, 54(3):131-137 | DOI: 10.17221/3099-JFS The collection and sale of asparagus (Asparagus racemosus Willd.) is a major source of income for Praja and Tamang castes around the Royal Chitwan National Park (RCNP) in Nepal. However, the forests where asparagus is harvested are becoming depleted threatening the livelihood of collectors. To address this issue, at sustainable harvesting practices, the research reported here applied the contingent valuation method (bidding game) and estimated the average willingness to pay (WTP) of collectors to two asparagus collection scenarios. In the first scenario, if forests under the Department of Forests jurisdiction were managed for sustainable harvesting at 1995 rates, the average WTP of collectors was 4.4 NR/kg. In the second scenario, if the forest in the RCNP is managed in such a way that both the current harvesting rate of asparagus is sustained and they are legally allowed to collect asparagus at the present rate, the average WTP of collectors was 8.35 NR/kg. Consequently, there is a good chance of earning revenue for the government and sustaining the livelihood of asparagus dependents by the sustainable management of the Department's and the National Park's forests and giving legal permissions to collect asparagus from the National Park, which would have happened anyway but with financial and legal risks to collectors. |
Intensively fertilised seedlings of the beech (Fagus sylvaticaL.) for artificial regeneration of the spruce stands in the process of conversionA. Jurásek, J. Bartoš, J. NárovcováJ. For. Sci., 2008, 54(10):452-458 | DOI: 10.17221/41/2008-JFS Artificial regeneration of autochthonous target tree species plays an important role in the process of conversion of forest stands. The European beech is one of the most suitable and most frequently used tree species in this process. Modern technologies of intensive methods of the cultivation of the European beech seedlings provide, among others, a possibility to increase the proportion of this tree species in reforestation more quickly. It is however necessary to test at what types of sites this planting material can be used. The health status and growth of intensively grown beech seedlings in the first years after planting were studied on 2 research plots. Proper intensive fertilisation of the beech seedlings affected positively both the initial height and growth. Even the slow-release fertiliser did not negatively influence the beech after planting. The health status of the beech is excellent after 4 years, the average height of plants with different fertilisation treatments having become equal. It is to conclude from the hitherto obtained results that a slow-release fertiliser in the substrate has a positive effect on the plant growth, and that different fertilisation variants did not cause any serious root deformations of the beech planting stock samples taken 4 years after planting. The impacts of prior nursery fertilisation upon the beech planted under the conditions of extreme sites are further investigated. |
Analysis of forestry financing in the Czech Republic in the period of transition to market economyL. Šišák, M. ChytrýJ. For. Sci., 2004, 50(2):78-85 | DOI: 10.17221/4603-JFS The article is devoted to problems of forestry financing in the Czech Republic in the period of transition to market economy (1991-1999). The policy of forestry financing is aimed above all at the provision and improvement of quality of sustainable non-market forest goods and services. Thirty programmes and 46 sub-programmes were analysed in the CR in 1991-1999. The level of financial support ranged from 909.4 mil. CZK to 1,501.7 CZK with the exception of 2,540.1 mil. CZK in 1991 (all in stable 1999 prices). On average, the support amounted to about 10% of the GDP created by the forestry sector in the given period. |
Forest topsoil organic carbon content in Southwest BohemiaregionE. Cienciala, Z. Exnerová, J. Macků, V. HenžlíkJ. For. Sci., 2006, 52(9):387-398 | DOI: 10.17221/4519-JFS The aim of this study was to evaluate organic carbon content (SOC) in the surface layers of forest soils in the two Natural Forest Regions situated in Southwest Bohemia, namely Západočeská pahorkatina (NFR 6) and Český les (NFR 11). The study is based upon on two consecutive soil sampling campaigns during autumn 2003 and 2004. While the sampling of 2003 was inadequate to estimate bulk density, the consecutive campaign used a defined sample volume to permit an estimation of bulk density and quantification of soil organic carbon (SOC) for soil organic layers and the upper mineral horizon. The total sampling depth was 30 cm including both organic and mineral layer. SOC of organic horizon was on average 1.99 kg C/m2. It differed by stand site type ranging from 0.70 to 3.04 kg C/m2. The organic layer SOC was smallest under beech (1.03 kg C/m2), whereas it was higher under pine (2.19 kg C/m2) and spruce (2.09 kg C/m2). SOC in the mineral layer was in average 7.28 kg C/m2. SOC differed significantly by the major tree species and reached 10.6; 5.67 and 7.5 kg C/m2 for beech, pine and spruce sites, respectively. The average SOC for the total soil layer (0-30 cm) reached 9.33 kg C/m2. The methodological aspects of regional estimation of SOC and the potential of utilization of the national forest inventory program are also discussed. |
Web-spinning sawflies of the genus Cephalcia Panzer (Hymenoptera, Pamphiliidae) in the Picea abies forests of the Beskidy Mountains (Poland)M. JachymJ. For. Sci., 2007, 53(20):63-68 | DOI: 10.17221/2149-JFS This article presents a review of data and results of investigations from the period 1958-2006 regarding the occurrence of insects of the genus Cephalcia Panzer (Hymenoptera, Pamphiliidae) in Norway spruce stands of the Beskidy Mountains (Western Carpathians, southern Poland). Currently, eight species are known for the area: C. abietis, C. alashanica, C. alpina, C. annulicornis, C. arvensis, C. erythrogaster, C. fulva and C. masuttii. Information regarding each species is given, with details on identification, local occurrence and importance. |
The financing of non-market forest servicesOriginal PaperI. Kolenka, K. PulkrabJ. For. Sci., 2002, 48(11):508-511 | DOI: 10.17221/11919-JFS The article deals with issues of non-market forest services. There is a persistent issue complicating the quantification of adequate subsidy to forest owners - non-existence of market with such forest services. Forest services financing can be made objective by implementation of the following steps: 1. Earmarking of non-market forest services that are becoming market subjects gradually. 2. Earmarking of non-market forest services that create a secondary product of wood production function. 3. Quantification of demand for services. 4. Quantification of costs necessary to cover the demand for those forest services. 5. Quantification of losses caused to forest owners by restricting their economic activities. |
Elementary financial analysis of the Forests of the Czech Republic, state enterpriseV. KupčákJ. For. Sci., 2005, 51(3):127-140 | DOI: 10.17221/4551-JFS The basic feature of an economic reform of the forestry in the Czech Republic after 1990 was separation of supervision in the state forests from operating performance. The Forests of the Czech Republic, state enterprise, was charged with management and supervision, hence economic activities of the subject are provided on the basis of contracts by entrepreneurial units called contractors in the forestry. The purpose of the paper is economic analysis of the Forests of the Czech Republic, state enterprise, in the period 1998-2002. The objective is the construction and testing of an elementary method of financial analysis as well as outline of financial situation and development of the chosen subject generally. The paper contributes to branch economy analysis, common in agriculture and wood-processing industry. |
Recreational load as a driving variable for urban forestsI. KupkaJ. For. Sci., 2006, 52(7):324-328 | DOI: 10.17221/4514-JFS Green areas and urban forests represent important factors of urbanized environment which attracts more and more attention of forest management and silviculture. Recreational load and its types are the most important driving variable for the management framework in which basic silvicultural methods should be applied. The problem of the required combination of natural and social limits is resolved by a matrix which takes into account forest ecosystem quality and recreation. The matrix defines 9 or 27 units (their number depends on the fact if we take into account the age of stand or not) for which basic management rules could be prepared. The basic rules concerning biological aspects are described in a general way in the article. |
Importance of non-wood forest product collection and use for inhabitants in the Czech RepublicL. ŠišákJ. For. Sci., 2006, 52(9):417-426 | DOI: 10.17221/4522-JFS The article investigates the socio-economic importance of collection and use of non-wood forest products (NWFP) for inhabitants in the Czech Republic (CR) in 2005 and brings a comparison with former investigations and research projects. The research project consisted of these parts in 2005: 1. Analysis of hitherto performed research projects and their results in 1999-2003, 2. Investigation of quantities and values of NWFP collected in 2004 and 2005, 3. Specific investigation of socio-economic importance of NWFP collection and use. The results of respective investigations prove NWFP collection being quite important for the inhabitants of the CR. The importance consists in the material value of picked commodities on the average annual level higher than 3,000 mil. CZK. Nevertheless, collecting NWFP is considered as a very important recreational activity. Only a small part of the population collecting NWFP (about 12%) collects NWFP to save money. |
Economic effectiveness of sustainable forest managementK. PulkrabJ. For. Sci., 2006, 52(9):427-437 | DOI: 10.17221/4523-JFS The article deals with economic aspects of sustainable forest management. The analysis stems from Plíva's typological system. Several hundreds of variants were calculated for forest silviculture profitability classified according to management intensity, target management system, proportion of ameliorating and improving species, proportion of natural regeneration, and set of forest types. The results show a possibility of labour saving and also marked differentiation of the effect of wood production function depending on natural and production conditions and management intensity. |
Financing of forestry from public funds in the Czech Republic, Estonia, Poland and Slovenia - policy context, organisation and supported activitiesA. KaliszewskiJ. For. Sci., 2004, 50(4):181-189 | DOI: 10.17221/4613-JFS The paper describes the policy, legislative and organisational context and structure of financing the forestry from public funds in the Czech Republic, Estonia, Poland and Slovenia in the 90's. The first half of the nineties was the period of the most significant changes, whereas more stable and systematic financing of forestry was generally started in the second half of the nineties. The supported activities reflected main problems and challenges facing the forestry in individual countries. In the Czech Republic the substantial support was designed for protective measures and restitution of damaged stands. In Poland, the increase of forest area and restitution of forest stands damaged by air-pollution were the priority. Slovenian budget supported mainly the improvement of road infrastructure, forest management planning, as well as sustainable utilisation of forests through marking of trees for cutting. Estonian forestry received the relatively lowest subsidies allocated mainly to the preparation of management plans and extension services. Subsidies were the most important instruments of support. In Poland, however, tax exemptions and concessions were significantly higher than the value of financial means allocated from the public funds. |
The policy process on climate changeZ. Sarvašová, A. KaliszewskiJ. For. Sci., 2005, 51(3):108-114 | DOI: 10.17221/4549-JFS The United Nations Framework Convention on Climate Change accepted in 1992 at the Earth Summit in Rio de Janeiro provides principles and framework for cooperative international action on mitigating climate change. But it soon became clear that more radical targets were needed to encourage particular countries to reduce greenhouse gas emissions. In response, countries that have ratified the United Nation Framework Convention on Climate Change accepted the Kyoto Protocol in 1997. The rulebook for how the Kyoto Protocol will be implemented - the Marrakech Accord, was agreed in 2001. This paper describes political instruments and facilities of mitigating climate change by forestry proposed in those political documents. |
From timber management to forest management: an initial discussion on forest management evolutionM. S. IftekharJ. For. Sci., 2005, 51(9):412-429 | DOI: 10.17221/4576-JFS Forests have been subject to human intervention since the inception of human civilization. With enhanced knowledge, understanding and capacity humans exert an increasing pressure and influence on forests. Forests in general have undergone different ownership patterns. The requirements for forests have changed over time. The objectives of forest management are shifting from timber production to biodiversity conservation and nature protection. On the other hand, in many places the forests are dwindling due to the anthropic pressure. The management paradigms are changing in response to these triggering mechanisms. In this paper an attempt has been made to summarize the evolution of forest management practices and discuss some recent trends in forest management. |
Evaluation of changes in the tree species composition of Czech forestsI. TomáškováJ. For. Sci., 2004, 50(1):31-37 | DOI: 10.17221/4598-JFS The tree species composition of forests in the Czech Republic has changed due to the human impact over the time. Nowadays, the idea of reducing the area with spruce stands and of increasing the area with broadleaved stands is widely discussed. The paper compares the target species composition with the presentone and creates four groups of areas with the largest and/or negligible differences between the target and the actual tree species composition using the Czech typology school. |
XII. World Forestry CongressK. Vančura, S. VacekJ. For. Sci., 2004, 50(11):497-499 | DOI: 10.17221/4645-JFS XII. World Forestry Congress have been held in Quebec, Canada from September 21 to 28, 2003. Forestry issues were discussed on three basic areas: Forests for People, Forests for the Planet, People and Forests in Harmony. The Czech Republic was represented by 9 contributions. |
National Forestry Programme of the Czech Republic in briefK. VančuraJ. For. Sci., 2004, 50(11):500-504 | DOI: 10.17221/4646-JFS The basic principle from which the Czech National Forestry Programme proceeds is the management of forests in a permanently sustainable manner whilst limiting the administrative interference of the state to the unavoidable minimum under the circumstances of the motivating operation of state forestry policy for the support of public interests and whilst increasing the responsibility of forest owners for their property. The National Forestry Programme is supposed to be an interdepartmental and intersectoral programme respecting not only the needs for the branch development of forest management, but also emphasising the place of forests in the environment and landscape creation, non-production functions of forests, the importance of the forest as a renewable source of ecologically advantageous raw material and the significance of the use and processing of wood for the economy of the country and thus for the society as such. The first idea of National Forestry Programme has been presented in 1993. The current version of the Programme has been conceived for the period 2003-2006. In addition to the basic information about the current state of forests and forestry management in the Czech Republic, it contains chapters with themes focussing on forestry problem issues. |
Development of the Czech forest related policy and institutions in the threshold of the 3rd millenniumK. Vančura, P. Pacourek, J. ŘezáčJ. For. Sci., 2004, 50(11):505-509 | DOI: 10.17221/4647-JFS This paper gives an overview of Czech forestry policy and legislation since the beginning of changes in the CEEC plus developments and activities of the main forestry institutions. These activities are referred to in the background material given for the political transition period and also related to the Pan-European and global forestry processes. The philosophy of forestry in the Czech Republic is based on the international framework set out by the first Ministerial Conference on the Protection of Forests in Europe and also in conjunction with the preparation of the Czech Republic for accession to the European Union. National and regional forest programmes are aimed at implementing the principles of sustainable forest management and a broad range of stakeholders from the forestry and environment sectors has been involved in its preparation. The current situation and main problems of forestry are given along with basic principles on how to solve such problems and also on how to fulfil obligations to future generations, and international commitments. |
Development of forest stands condition and its monitoring in the Czech RepublicP. Fabiánek, V. Henžlík, K. VančuraJ. For. Sci., 2004, 50(11):514-519 | DOI: 10.17221/4649-JFS In 1986, the UN ECE established the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (hereinafter ICP Forests) to respond on the growing concern about forest damage caused since the beginning of eighties by air pollution load. Pan-European grid of the (ICP Forests) monitoring plots represents one of the most important systems of forest ecosystems assessing and checking. The Czech Republic is unfortunately well known due to this problem and so the country joined ICP Forest Programme since the very beginning. The paper presents general information on Czech forest stand condition that gained through various methods in the past as well as in the frame of ICP Forests. The participation in the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) represents a contribution of the EU candidate country to the fulfillment of the Reg. (EEC) No. 3528/86. However it seems that effects and importance of air pollution are decreasing, a lot of new stress situations exists and there is a need for continuing the programme. |
XII. World Forestry Congress and its conclusionsK. Vančura, S. VacekJ. For. Sci., 2004, 50(11):548-552 | DOI: 10.17221/4655-JFS |
Economic analysis of forest joint-stock companies in the Czech Republic in 1992-2000V. KupčákJ. For. Sci., 2003, 49(1):27-36 | DOI: 10.17221/4675-JFS The basic principle of the economic reform of state forests of the CzechRepublic after 1990 was to separate management in forests from the implementation of production activities. A state enterprise Forests of the Czech Republic with its headquarters in Hradec Králové was charged to manage state forests. From the former 7 enterprises of state forests 78 joint-stock companies have been established that carry out silvicultural and logging activities in state forests and in forests of other owners under the conditions of competition environment and on the basis of contracts. The paper deals with the exact evaluation of partial and present results of the development of forestry economic reform, aimed at the study of the behaviour of transformed and privatised forest joint-stock companies. |
Occurrence, development and natural enemies of Pemphigus spyrothecae (Homoptera, Pemphigidae)Original PaperJ. UrbanJ. For. Sci., 2002, 48(6):248-270 | DOI: 10.17221/11883-JFS In 2001, galls were analysed of Pemphigus spyrothecae Pass. taken in one- to three-week intervals from Populus nigra and P. nigra var. italica at 4 localities in Brno. Fundatrices matured in the first half of June and during the first half of summer produced about 50 offsprings. Virgines produced about 10 offsprings which grew up in winged sexuparae. The winged individuals started to occur in galls from the beginning of August. In galls with intact development, on average 500 aphids developed. Galls with intact development on P. nigra var. italica reached larger average dimensions and contained at least by 4% more aphids than galls on P. nigra. About 5% of fundatrices died already in the 1st instar and other 3 to 6% in higher instars by the beginning of reproduction. At localities under investigation, 7.5 to 39.0% of galls on P. nigra and 3.9 to 13.7% of galls on P. nigra var. italica were occupied by the fly Leucopis puncticornis Meig. (Chamaemyiidae). About 24.3 to 32.2% of galls on P. nigra and 23.3 to 49.3% of galls on P. nigra var. italica were occupied by the bug Anthocoris minki Dohrn (Anthocoridae). Hover flies Heringia heringi (Zett.) and Pipiza festiva Meig. (Syrphidae) killing aphids in 3.8 to 30.4% of galls on P. nigra and 6.5 to 6.8% of galls on P. nigra var. italica were an important regulator. In August (i.e. at the beginning of the formation of winged sexuparae), the majority of galls opened through primary slit-shaped or oval emergence holes. A part (7.8 to 19.5%) of galls with so far intact development, however, remained closed and all aphids contained in them died. Diseases (particularly mycoses) often participated in the accelerated dying of aphids. The effect of mortality factors on the gall size differentiation was evaluated in details. The galls do not cause any leaf area reduction. In the case of mass outbreak, they decrease decorativeness of poplars in street alleys. In August and September, liquid excrements fall out from the galls (honeydew) polluting the environment in villages and housing estates. |
