Havasova M.,Slovak Academy of Sciences |
Havasova M.,University of Oregon |
Ferencik J.,Research Station |
Jakus R.,Slovak Academy of Sciences |
Jakus R.,Czech University of Life Sciences
Forest Ecology and Management | Year: 2017
Natural disturbances such as windthrow and bark beetle Ips typographus L. outbreak often affect protected areas with non-intervention type of management located in close proximity to managed forest stands. This raises concerns about the migration of the beetle outbreak from non-intervention zones to adjacent managed forests. In this study we analyzed the spatiotemporal dynamics of large-scale disturbances by intervention and non-intervention type of management in the Tatra mountains (Central Europe). We collected a time series of Landsat images from 2003 to 2014, and applied maximum likelihood classification to map the extent of forest, windthrow, clear-cuts, beetle outbreak and fire. Our classified maps achieved high overall accuracies: 0.93 ± 0.03 ⩽ OA ⩽ 0.96 ± 0.03. The extent of forest declined over the study period. We found higher rate of beetle induced tree mortality in non-intervention versus intervention zone. Within two growing seasons after the windthrow, beetle infestation occurred in close proximity to uncleared windthrow (<∼250 m), which suggest the positive effect of salvage logging (removal of windthrown trees) on lowering the risk of beetle outbreak. The two times higher sum of disturbances in intervention then in non-intervention zone indicated the limited impact of sanitation felling (removal of standing beetle infested trees) to reduce beetle population. However, sanitation felling highly contributed to the decline of the forest cover. Overall, our results document the dynamics of windthrow, bark beetle and clear-cuts by type of management, and limited impact of logging activities in reducing beetle outbreak in neighboring areas with intervention and non-intervention type of management. © 2017 Elsevier B.V.
Tomer A.S.,Research Station |
Dubey S.P.,Rungta Colllege of Engineering and Technology
International Journal of Electrical and Computer Engineering | Year: 2016
This Paper gives a complete modeling and simulation of a two inverter fed six phase permanent magnet synchronous motor drive system, Then response based comparative analysis is done on starting torque, settling time, Steady state current at various speed levels and torque levels by changing proportional-integral (PI) controller to Fuzzy logic controller. The PI controller has some disadvantages like, more settling time, sluggish response due to sudden change in load torque etc. So an intelligent controller, based on fuzzy logic is introduced which replaces the PI-controller and its drawbacks. The performance of both the controller has been investigated and studied by comparing the different plots obtained by setting various speed level both incremented and decremented speed, at different load conditions like No-load, fix load and dynamic load through Matlab / Simulink environment. Finally it is concluded from the result that fuzzy logic based controller is robust, reliable gives quick response with high starting torque and more effective than the conventional PI controller. It is also observed that both the proposed model can also run above rated speed significantally. Copyright © 2016 Institute of Advanced Engineering and Science. All rights reserved.
Riar D.S.,Soil and Environmental science |
Norsworthy J.K.,Soil and Environmental science |
Steckel L.E.,University of Tennessee |
Stephenson IV D.O.,Research Station |
Bond J.A.,Delta Research and Extension Center
Weed Technology | Year: 2013
A survey questionnaire was sent to cotton consultants of Arkansas and Mississippi through direct mail and Louisiana and Tennessee consultants through on-farm visits in fall of 2011. The survey was returned by a total of 22 Arkansas, 17 Louisiana, 10 Mississippi, and 11 Tennessee cotton consultants, representing 26, 53, 13, and 38% of total cotton planted in these states in 2011, respectively. Collectively, the area planted to glyphosate-resistant (Roundup Ready®, RR) cotton was 97%, glyphosate plus glufosinate-resistant (Widestrike® Flex, WRF) cotton was 30%, and glufosinate-resistant (Liberty Link, LL) cotton was 2.6% of the total cotton surveyed in 2011. Seventy percent of area in all states is still under continuous RR/WRF cotton. Average cost of herbicides in RR systems was $ 114 ha-1 and in LL systems was $137 ha-1. Across the states, cotton planted under no-tillage, conservation tillage, and conventional tillage was 31, 36, and 33%, respectively, of total scouted cotton. Area under conventional tillage increased and conservation tillage decreased in Arkansas compared with a previous survey conducted in 2006. Palmer amaranth, morningglories, and horseweed in the order of listing were the most problematic weeds of cotton across Arkansas, Mississippi, and Tennessee. In Louisiana, however, morningglories were the most problematic weed followed by Palmer amaranth and common waterhemp. Glyphosate-resistant (GR) Palmer amaranth infested only 13% of scouted cotton area in Louisiana compared with 75% in the remaining three states, and consequently, hand-weeding to control GR Palmer amaranth is practiced on only 2.5% of total scouted area of Louisiana and 49% of the scouted area of the remaining three states. Hand-weeding added an additional $12 to 371 ha-1 to weed-management costs. One-half (50%) of the cotton consultants emphasized the need for more research on residual herbicides that can control GR Palmer amaranth effectively.
Panek M.,Research Station |
Husek J.,Hedmark University College
Bird Study | Year: 2014
Capsule The occurrence of oilseed rape increased main prey abundance and breeding success of Common Buzzards.Aims We tested whether the occurrence of oilseed rape influences the abundance of Common Voles, i.e. the main prey of Common Buzzards and so also nesting activity and breeding success of Common Buzzards.Methods The study was carried out in 2005-2012 in a 38km2 area in western Poland, where oilseed rape plantations (12-106ha) covered 18% of the agricultural land. The number of active burrow entrances was used as an index of vole abundance in various crops, and Buzzard breeding performance, i.e. the occurrence of annual nesting attempts in individual long-term nesting sites as well as the presence and number of fledglings, was estimated by observations of their nests.Results The index of vole abundance was highest in oilseed rape, and judging by the proportion of active burrow entrances (33-77%), the plantations of rape typically supported a larger portion of the local vole population than other crops. The acreage of oilseed rape fields around individual nesting sites of Buzzards did not affect the probability of nesting attempts in these sites. However, the probability of successful nesting and the number of fledglings per successful nest increased with the area of oilseed rape around the Buzzard nesting sites.Conclusion The occurrence of oilseed rape may positively affect prey availability and in turn the breeding success of Buzzards. The spread of oilseed rape may therefore also be beneficial for other vole-eating raptors hunting in the agricultural landscapes. © 2014 British Trust for Ornithology.
Orowski G.,Polish Academy of Sciences |
Czarnecka J.,Maria Curie Sklodowska University |
Panek M.,Research Station
Bird Study | Year: 2011
Capsule Diet composition differed significantly between winter cereals, winter oil-seed rape, stubble fields and permanent fallows. Aims To determine the composition of the diet of Grey Partridges in autumn and winter in four agricultural land-cover types, characteristic of lowland areas of Central Europe. Methods Faecal analysis was used to determine diet. Multivariate analysis of variance (manova), Simpson Index of Diversity (sid) and Detrended Correspondence Analysis (dca) were used to assess variation in the proportions of the six main dietary components (cereal and broad-leaved plant leaves, weed seeds cases, cereal grains, husks of grasses and other plant material). Results Thirty-seven different kinds of plant food items were found, and the most numerous were cereal leaves (58.2% in total of all items), followed by leaves of broad-leaved plants (21.8%), weed seed cases (13.3%), cereals grains (3.5%), husks of grasses (1.2%) and other plant material (2.0%). Diet composition differed significantly between winter cereals, winter oil-seed rape, stubble fields and permanent fallows. The dca showed that the two first axes explain 38% of the total variance of the diet. The diet diversity was highest in stubble fields and permanent fallows, and the smallest in winter cereals. Dietary diversity was negatively correlated with the overall abundance of leaves, and positively with the abundance of weed seeds, cereal grains and husks of grasses. Conclusion Cereal leaves might replace other food items, which suggests that food resources are not a critical factor limiting the population of Grey Partridges during winter. A high proportion of weed seeds and cereal grains in the diet of Grey Partridges in stubble fields confirms the importance of these fields as sources of food of high-calorific value. Maintenance of stubble fields and cover crops with natural regeneration of annual weeds should constitute an important element of a strategy for the recovery of Grey Partridge populations in arable landscapes in Europe. © 2011 British Trust for Ornithology.
Tantau H.-J.,Leibniz University of Hanover |
Schmidt U.,Humboldt University of Berlin |
Meyer J.,TU Munich |
Bessler B.,Research Station
Acta Horticulturae | Year: 2011
The increase of energy costs and the task of reducing CO 2-emission of fossil fuels require solutions for low energy greenhouses. Until now greenhouses are mainly covered with single glazing providing high light transmittance for a good crop performance. In the meantime, several solutions have been developed to reduce the energy consumption of greenhouses like double-glazing, thermal screens and specific control algorithms. Such measures influence the light transmittance of the covering material and the greenhouse microclimate - especially air humidity. This may lead to a reduction of yield and an increase of fungi infections. The control of air humidity can increase the energy consumption, thus reducing the energy saving potential. Hence it is necessary to develop a low energy greenhouse concept as a system approach combining energy saving methods with an improved control of greenhouse microclimate. In the past, several low greenhouse concepts had been developed with a focus on covering materials and thermal screens. Recently, the closed greenhouse concept has been developed and propagated as an energyproducing greenhouse. The closed greenhouse is an example for a concept to reduce energy consumption and at the same time to increase yield and crop quality. The energy saving potential of such a greenhouse has been reported to be in the range of 20 to 33% and the increase of yield up to 20% (Opdam et al., 2005). A low energy greenhouse can have a higher energy saving potential of up to 90%. This is rendered possible by combining different methods, which have been developed in the past, with new approaches. The greenhouse should be operated semi-closed, allowing a better application of CO 2 in order to improve crop performance, reduce the application of pesticides and promote the use of solar energy for heating. New cladding materials with anti-reflective coating are available with high light transmittance allowing double-glazing with the same light transmittance as conventional single glazing. In combination with triple thermal screens a maximum insulation is possible. Using new concepts of climate control strategies such as temperature integration, a further reduction of energy consumption is possible. Since all these methods influence the greenhouse climate, the crop response must be investigated by phytomonitoring in order to determine limitations and to avoid negative effects. Furthermore, improving the cropping system and using new cultivars can contribute to the low energy greenhouse concept.
Panek M.,Research Station
Population Ecology | Year: 2016
Distinct numerical responses of predators to fluctuations in the abundance of their prey are often observed in northern regions but occur more rarely in temperate latitudes. This statement is, however, mostly based on observations of breeding populations, while in some predators, for example in raptors, numerous non-breeding floaters can occur. I estimated the breeding density and reproductive performance (nest survey) as well as the density of entire population (transects with distance sampling) of the common buzzard Buteo buteo in western Poland (52°N) in the years 2005–2014 to test the hypotheses that in temperate latitudes: (1) the breeding population of these birds does not show any numerical response, understood as annual changes in their abundance; (2) its reproductive success, however, changes with the abundance of main prey, the common vole Microtus arvalis; and (3) hence the entire buzzard population (including potential immature floaters) present in a given area during the nesting period responds numerically with some time delay. The reproductive success of buzzards was positively correlated with their prey abundance. Contrary to my predictions, however, the breeding population of buzzards showed a slight numerical response with a 3-year lag and the entire population tracked vole fluctuations without any time delay. The immediate numerical response of the entire buzzard population was probably caused by large-scale movements of floaters. Such rapid numerical responses of some predators may contribute to the relative stability of prey populations in temperate latitudes compared to northern regions. © 2016 The Society of Population Ecology and Springer Japan
Panek M.,Research Station
European Journal of Wildlife Research | Year: 2013
The aim of this study was to estimate long-term changes in the winter feeding pattern of red foxes Vulpes vulpes and in their predation on brown hares Lepus europaeus in relation to the decreasing abundance of hares in western Poland in 1965/1966-2006/2007. The frequencies of occurrence in the stomachs of culled foxes (N = 726) were used as indices of prey capture rates. The average autumn density of brown hares in the study area decreased from 48 individuals/km2 at the turn of the 1960s and 1970s to seven individuals/km2 in 1999-2006. Hares and small rodents were the main food classes of foxes in western Poland at the turn of the 1960s and 1970s; however, the occurrence of hares in the fox diet subsequently decreased, and they were replaced by livestock carrion. The relationship between the occurrence frequency of hares in the fox diet and the hare density was best described by sigmoid equation. It indicates that the red fox showed a type III functional response to long-term changes in hare abundance. When predation rate index was estimated on the basis of functional response, the potential fox predation was density-dependent at low to intermediate hare densities (<25 individuals/km2). This finding suggests that the increase in the number of low-density hare populations may require intensive management measures, e.g. simultaneous use of fox control and habitat improvement. © 2013 Springer-Verlag Berlin Heidelberg.
Zielonka T.,Polish Academy of Sciences |
Holeksa J.,Polish Academy of Sciences |
Fleischer P.,Research Station |
Kapusta P.,Polish Academy of Sciences
Journal of Vegetation Science | Year: 2010
Question: Have past windstorm events influenced the structure and composition of mountain forests in the Tatra Mountains? Can severe and infrequent wind disturbances lead to dynamic coexistence of two tree species with different ecological requirements? Location: Subalpine mixed spruce-larch forest at 1200-1300ma.s.l. in the Slovakian Tatra Mountains. A forested site affected by catastrophic largescale windthrow on 19 November 2004. Methods: Sixty-seven spruce and 30 larch crosssections from the oldest cohorts were collected in a regular pattern in a 100-ha plot. Tree-ring series were analysed to reconstruct growth releases associated with past windthrows. A boundary-line release criterion was applied to detect disturbance year. Spatial patterns of release signals were statistically detected with Mantel's test. We compared reconstructed years of disturbance events with historical records. Results: Releases in both species showed three main pulses. More than 85% showed major or moderate releases in 1865-1879, 48% in 1915-1924, and 25% in 1940-1949. All of these disturbance events affected the whole 100-ha area. Releases were spatially patterned in the first disturbances, but distributed randomly in the last. Releases co-occurred in time with enhanced production of compression wood, suggesting disturbances were of wind origin. Reconstructed dates of windthrows were confirmed using historical data on storms. Conclusions: At least three windthrows of major and moderate severity took place in the last 150 years on southern slopes of the Tatra Mountains. This disturbance regime may contribute to coexistence of spruce and larch through differences in vulnerability and response to heavy windstorms. © 2009 International Association for Vegetation Science.
Panek M.,Research Station
Central European Journal of Biology | Year: 2013
The aim of this study was to estimate the effect of agricultural landscape structure on the predation rate of red foxes Vulpes vulpes on grey partridges Perdix perdix during the breeding season and on their spatial relations. The number of partridge remains found around fox breeding dens (N=165) was used as an index of the predation rate in 10 study areas. Moreover, the distribution of both species and the searching intensity of partridge nesting habitat (permanent semi-natural vegetation) by foxes in relation to the landscape structure were studied using scat, track and call counts. The predation index (range 0.06-0.46 partridges/den) increased with spring partridge density and decreased with the occurrence of crop boundaries. The distribution of foxes and partridges in large fields was positively correlated with the occurrence of permanent vegetation, but no such effect was observed in small fields. The searching intensity in permanent vegetation by foxes decreased with the occurrence of these structures among small fields, but not among large fields. The study showed that in a differentiated landscape foxes and partridges had various structural elements at their disposal, which led to partial separation of the predator and its prey in the space. © 2013 Versita Warsaw and Springer-Verlag Wien.