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Učinkovitost ulova smrekovih podlubnikov v dvojne in trojne kontrolno-lovne pasti
Nikica Ogris, 2022, original scientific article

Abstract: Osmerozobi smrekov lubadar (Ips typographus) in šesterozobi smrekov lubadar (Pityogenes chalcographus sta najpomembnejša škodljivca navadne smreke (Picea abies) v osrednji Evropi in tudi v Sloveniji. Kontrolno-lovne pasti, opremljene s feromonskimi vabami, uporabljamo za ocenjevanje številčnosti smrekovih podlubnikov. Cilj raziskave je bil izračunati povprečno razmerje (mediano) ulova osmerozobega smrekovega lubadarja in šesterozobega smrekovega lubadarja med dvojnimi in enojnimi ter trojnimi in enojnimi kontrolno-lovnimi pastmi. Za ta namen smo uporabili podatke s spremljanja številčnosti smrekovih podlubnikov v režastih pasteh vrste Theysohn, tj. uporabili smo podatke iz 19.140 enojnih pasti, 4.347 dvojnih pasti in 991 trojnih pasti, ki jih je Zavod za gozdove Slovenije spremljal v letih 2013–2021. V dvojno past se je povprečno ujelo 1,17-krat več osebkov I. typographus kot v enojno. Ulov šesterozobega smrekovega lubadarja v dvojno past je bil v povprečju enak kot v enojni pasti. Ulov osmerozobega smrekovega lubadarja v trojno past je bil v povprečju 1,58-krat večji kot v enojno. V trojno past se je povprečno ujelo 1,54-krat več osebkov P. chalcographus kot v enojno. Preverili smo tudi vpliv izbranih dejavnikov na razmerje ulova v pasteh: (1) razlika v začetku spremljanja; (2) razlika v nadmorski višini; (3) pasti je čistila ista oseba; (4) oddaljenost od druge pasti; (5) razlika v razdalji do najbližjega žarišča. Na mediano razmerja ulova je najbolj vplivala oddaljenost od drugih pasti. Na mediano razmerja ulova I. typographus v trojno past sta zaznavno vplivala tudi začetek spremljanja in razlika v nadmorski višini med primerjanima pastema. Ničen vpliv na mediano razmerja med trojno in enojno pastjo je imel pogoj, da je pasti čistila ista oseba. Izračunana povprečja bomo uporabili za točnejši preračun kumulativnega ulova v dvojne in trojne kontrolno-lovne pasti na eno past, saj smo za to doslej uporabljali konstanti dve za dvojne in tri za trojne pasti, kar je bistveno več od dejanskih razmerij. To bo pripomoglo k zanesljivejšim ocenam o prenamnožitvah na lokacijah pasti, kjer uporabljamo podatke iz spremljanja ulova v dvojne in trojne kontrolno-lovne pasti.
Keywords: osmerozobi smrekov lubadar, Ips typographus, šesterozobi smrekov lubadar, Pityogenes chalcographus, kontrolno-lovna past, abundanca, učinkovitost ulova, režasta past vrste Theysohn
Published in DiRROS: 17.10.2022; Views: 197; Downloads: 59
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Combining an occurrence model and a quantitative model for the prediction of the sanitary felling of Norway spruce because of bark beetles
Maarten De Groot, Nikica Ogris, 2022, original scientific article

Abstract: The European spruce bark beetle (Ips typographus L.) is an eruptive forest pest that has caused a great deal of damage in the last decades because of increasing climatic extremes. In order to effectively manage outbreaks of this pest, it is important to predict where they will occur in the future. In this study we developed a predictive model of the sanitary felling of Norway spruce (Picea abies (L.) H. Karst.) because of bark beetles. We used a time series of sanitary felling because of bark beetles from 1996 to 2020 in Slovenia. For the explanatory variables, we used soil, site, climate, geographic, and tree damage data from the previous year. The model showed that sanitary felling is negatively correlated with slope, soil depth, soil cation exchange capacity, and Standard Precipitation Index (less sanitary felling in wet years). On the other hand, soil base saturation percentage, temperature, sanitary felling because of bark beetles from the previous year, sanitary felling because of other abiotic factors from the previous year, and the amount of spruce were positively correlated with the sanitary felling of Norway spruce due to bark beetles. The model had an R2 of 0.38. A prediction was performed for 2021 combining an occurrence model and a quantitative model. The model can be used to predict the amount of sanitary felling of Norway spruce due to bark beetles and to refine the risk map for the next year, which can be used for forest management planning and economic loss predictions.
Keywords: sanitary felling, prediction, Ips typographus, Picea abies, Slovenia, forecasting, insect outbreak forest pest
Published in DiRROS: 21.02.2022; Views: 319; Downloads: 272
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Private forest owner characteristics affect European spruce bark beetle management under an extreme weather event and host tree density
Maarten De Groot, Jurij Diaci, Kaja Kandare, Nike Krajnc, Rok Pisek, Špela Ščap, Darja Stare, Nikica Ogris, 2021, original scientific article

Abstract: In the last few decades, an increasing number and intensity of bark beetle outbreaks have plagued the forests of Europe and North America. Bark beetle management is directly related to forest owner characteristics, although this relationship is not well understood. The purpose of the study was to investigate the influence of forest owner characteristics on the amount and timing of sanitary felling under different disturbance regimes and quantities of Norway spruce. We combined different databases on sanitary felling, the timing of sanitary felling, and forest owner characteristics for Slovenia from 2014 to 2018 and analyzed the amount and timing of sanitary felling in relation to forest owner characteristics. We found that the timing in winter and the amount of sanitary felling were positively associated with the distance of the owner%s residence to the forest parcel. Larger parcels were more affected by bark beetles but did not have later timing of cutting in the summer period as was hypothesized. The timing of sanitary felling decreased with property size, while with the probability of sanitary felling, the effect of property depended on the ice storm and the amount of spruce. The size of the settlement, the permanent address of the private owner, and timing of sanitary felling were positively associated but also depended on the amount of spruce. Gender and age did not have an important influence on the amount and timing of sanitary felling. Forest owners are an important factor in effective bark beetle management. This study highlights the private forest ownership characteristics that should be emphasized in order to fight bark beetle outbreaks in the event of large-scale disturbances. Governments should support forest owners who are at greater risk of bark beetle outbreaks and less efficient in managing outbreaks. Furthermore, landowner characteristics should be included when forecasting bark beetle outbreaks.
Keywords: close-to-nature management, sanitary felling, Ips typographus, forest pest management, forest owner characteristics
Published in DiRROS: 22.03.2021; Views: 853; Downloads: 641
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Estimating the most effective and economical pheromone for monitoring the European spruce bark beetle
Nina Šramel, Andreja Kavčič, Marija Kolšek, Maarten De Groot, 2021, original scientific article

Abstract: In recent decades, there have been an increasing number of outbreaks of Ips typographus in Europe. A large amount of sanitary felling has taken place, with significant economic and ecological consequences. In order to anticipate such large%scale outbreaks, an effective monitoring system should be set up. One important aspect of monitoring is deciding which pheromone to use. Therefore, we decided to test five different commercially available pheromone lures under different disturbance conditions: Pheroprax%, IT Ecolure Extra%, Ipstyp%, Ipsowit% and Typosan%. We investigated the ability of the pheromones to distinguish between disturbed and undisturbed locations, their cost%efficiency ratio, and side effects such as bycatch abundance and composition. We set 50 traps in two areas with sites that were disturbed and undisturbed by windstorms. We collected the catch from traps every 1%2 weeks from the end of March until the end of September in 2019. We found that IT Ecolure Extra%, Ipsowit% and % Pheroprax% caught the most I. typographus and best showed changes in the trap catch of I. typographus throughout the whole season. There was a low amount of bycatch (<6% of the total catch) and a low number of predators (a few specimens), but some groups seem to prefer certain pheromones. The cost of the pheromones increased with their effectiveness. However, pheromone costs are low relative to the personnel costs involved in setting traps and collecting the catch. Based on all of the gathered data, we created an index which helps to assess the cost%efficiency of the five chosen commercially available pheromones. We also present guidelines on how to make such an index to assist other researchers in choosing the right pheromone for monitoring populations of I. typographus or other bark beetle species.
Keywords: bark beetles, cost-efficiency, Ips typographus, monitoring pheromones, Picea abies
Published in DiRROS: 21.01.2021; Views: 965; Downloads: 542
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