Christo Nikolov

Post-disaster Forest Management and Bark Beetle Outbreak in Tatra National Park, Slovakia

Abstract In November 2004, the Alžbeta windstorm hit the mountainous areas of northern and central Slovakia. The most affected area was Tatra National Park, where downslope wind damaged 12,000 ha of forest, mostly Norway spruce (Picea abies [L.] Karst.). In the areas with the highest level of nature conservation, about 165,000 m3 of damaged wood was left uncleared. These uncleared sites triggered a serious bark beetle outbreak, where Ips typographus (L.) was among the dominant species. The aim of our work was to quantify and map forest damage resulting from this windstorm and subsequent insect outbreak in Tatra National Park. The objective of this article is also to present simple geographic information system (GIS) techniques available to forest managers for the detection and mapping of bark beetle infestations. The infested areas were studied using GIS and a series of color-infrared aerial photographs taken in 2005–2009. More than 50% of all damage was recorded within 300 m, and more than 75% within 500 m, of uncleared windthrow sites. Based on our findings, we propose reinforcing post-disaster monitoring with an emphasis on (1) data acquisition and processing and (2) management of I. typographus outbreaks. For instance, we recommend using 300-m phytosanitary buffer zones in mountain spruce forests to prevent substantial beetle invasion from uncleared windthrow into adjacent stands.

Attraction of ambrosia beetles to ethanol baited traps in a Slovakian oak forest

The attractiveness of ultra high release ethanol lures to ambrosia beetles in Slovakian oak forests was tested from 2010 to 2012. A total of 24,705 specimens were captured during this three year period with Xyleborinus saxesenii (Ratzeburg, 1837) representing 49.28% (12,174 specimens) of the total. Other dominant species captured in the traps were Anisandrus dispar (F., 1792) (27.84%), Xyleborus monographus (F., 1792) (9.72%) and Trypodendron signatum (F., 1792) (6.04%). During this experiment, Xylosandrus germanus (Blandford, 1894) was detected for the first time in Slovakia with an increase in capture each year (19, 40 and 77 specimens, respectively). Flight period for ambrosia beetles in Slovakia occurs from the beginning of April through the end of September. This is the first time that ethanol baited traps were deployed in Slovakian oak forests and the lures were an effective tool for monitoring native and non-native ambrosia beetles.

Salvage felling in the Slovak forests in the period 2004–2013

Abstract Salvage felling is one of the indicators of the forest health quality and stability. Most of the European Union countries monitor forest harmful agents, which account for salvage felling, in order to see trends or functionality between factors and to be able to predict their development. The systematic evidence of forest harmful agents and volume of salvage felling in Slovakia started at the Forest Research Institute in Zvolen in 1960. The paper focuses on the occurrence of the most relevant harmful agents and volume of salvage felling in the Slovak forests over the last decade. Within the 10 years period (2004–2013) salvage felling in Slovakia reached 42.31 mil. m3 of wood, which was 53.2% of the total felling. Wind and European spruce bark beetle Ips typographus damaged 78.4% of salvage wood, i.e. they were the most important pest agents. Norway spruce (Picea abies) was the most frequently damaged tree species that represented the amount of 35.6 mil. m3 of wood (81.2% of total volume of salvage felling). As Norway spruce grows mostly in mountains, these regions of Central and Northern Slovakia were most affected. At the damaged localities new forests were prevailingly established with regard to suitable ecological conditions for trees, climate change scenarios and if possible, natural regeneration has been preferred. These approaches in forest stand regeneration together with silvicultural and control measures are assumed to gradually decrease the amount of salvage felling over long term perspective.

Influence of selected factors on bark beetle outbreak dynamics in the Western Carpathians

Abstract In the period from 1992 to 2013, more than 3.8 million m3 of spruce wood from an area of 55 thousand ha of forests in the Kysuce region (Western Carpathians) was affected by bark beetles. This region has had the highest volume of salvage fellings in Slovakia. While before 1991, bark-beetle outbreak usually occurred after snow and wind disturbances, since 1992 they have occurred in the years with extremely warm and dry growing seasons and the years following them. These years were also characterised by high volumes of wood affected by honey fungus (Armillaria spp.), which only rarely took part in the calamities before 1992. Extreme deterioration of the situation occurred after 2003. In fragmented and sparse stands, the volume of wood damaged by wind increased. Artificial origin of spruce stands, their high occurrence, high age and even-agedness are likely pre-disposing factors of spruce forest decline. Bark beetles have become the most important factor of spruce decline. The most important factors driving the bark beetle attack on forest stands in the period 1973–2013 were the amount of unprocessed wood in the previous year; the amount of wood affected by honey fungus, precipitation total, and average temperature in the current growing season. Another important factor that complicated the situation was also the inferior quality of forest management.

Survey tools and demographic parameters of Slovakian Agrilus associated with beech and poplar

Woodborers in the Agrilus genus (Coleoptera: Buprestidae) pose high invasiveness risk as indicated by the recent invasion and continental spread of emerald ash borer, and the associated threat to ash resources in North America. In that context, development of detection tools for potentially invasive Agrilus spp. is a research priority. Experiments carried out in 2013 in Slovakian beech and poplar forests evaluated the attraction of multiple Agrilus species to green and purple sticky prism traps baited with various lures [blank, cubeb oil, (Z)‐3‐hexenol]. The two most abundant species were Agrilus viridis L. in beech (Fagus spp.) forest (146 adults, >95% of which were females) and Agrilus convexicollis Redtenbacher in poplar (Populus spp.) forest (158 adults, two‐thirds of them males). The two species exhibited opposite responses to color: purple traps attracted 2–3× more adult A. viridis than green traps, whereas most (>95%) specimens of A. convexicollis were captured on green traps. Volatile baits did not influence captures of adults for either species. The introduction and establishment of A. viridis in North America is of particular concern owing to its feeding niche (primary pest that can attack healthy trees), large body size, and high level of polyphagy (>10 genera of host trees). Additional experiments conducted in beech forests in 2014 found purple prism traps more attractive to female A. viridis than green prism traps, especially those baited with cubeb oil. No analysis was conducted for males because of their low abundance. Female A. viridis flew earlier in 2013 than in 2014, but neither their body size nor fecundity varied between years. In both years, large females had more eggs in their abdomen than small females, and the number of eggs steadily declined over time, which suggests that female A. viridis are reproductively mature at emergence.

Effectiveness of pheromone traps for the European spruce bark beetle: a comparative study of four commercial products and two new models

Abstract Six types of pheromone traps were tested between 2012 and 2014 in the High Tatra Mountains, northern Slovakia. Traps were baited with lures for attracting the European spruce bark beetle (Ips typographus L.) (Coleoptera: Curculionidae, Scolytinae). Among the tested traps, four types are commercial products; Theysohn (T-trap), Ecotrap (E-trap), Lindgren funnel trap (L-trap), BEKA trap (B-trap) and two are our newly developed models; Funnel trap (P-trap) and Cross trap (K-trap). The traps were set up on ten selected sites and tested during three growing seasons (2012, 2013 and 2014). The newly developed models were compared to the commercially available models for trapping efficiency of target pest, easy to use and impact on non-target insect species. We found that the best commercially available model is the L-trap, however the bottom of L-trap is considered too shallow resulting in an accumulation of rainwater that increases the traps attractiveness for Silphids. In our experiment, the newly developed models; P-trap and K-trap performed better compared to commercially used models. P-trap caught 28% more I. typographus and K-trap caught 57% more beetles compared to T-trap in 2014. There are additional advantages of the newly developed traps such as easy handling, good rainwater drainage, higher collection container volume, and scale marking within the collection container. The results of this study have encouraged us to patent P-trap and K-trap as utility models.