Forest disturbances are intensifying globally, yet regional drivers of these dynamics remain poor... more Forest disturbances are intensifying globally, yet regional drivers of these dynamics remain poorly understood. We investigated recent disturbance intensities in Norway spruce (Picea abies L.) forests in Slovakia (Central Europe) with different management objectives in 2000–2017 based on Landsat imagery. We focused on 122 strict reserves without any management, their actively managed surroundings (500 m and 2000 m buffers), and managed production forests beyond the buffer areas. We used generalized additive mixed models to test for differences in temporal trends of disturbance intensity among these management categories. We found that disturbance intensity was increasing in all management categories during the studied period. The increase was more pronounced in the managed forests (compound annual disturbance rate 1.76% year−1) and the 2000 m buffer (2.21% year−1) than in the strict reserves (0.58% year−1). The predicted cumulative disturbance during the 18-year period was 9.9% in t...
The aim of this study was to develop methods for constructing a simple model describing tree mort... more The aim of this study was to develop methods for constructing a simple model describing tree mortality caused by Ips typographus L. using a minimum number of variables. We developed a model for areas spanning natural mountain forests in the Tatra National Park (Slovakia) and the Šumava National Park (Czech Republic), and in managed Czech forests located in four areas varying in environmental conditions. The model describes the time series of tree mortality dynamics caused by I.typographus using two submodels: a long-term dynamics submodel, and a short-term dynamics autoregressive distributed lag(ADL) model incorporating a two year delay and temperature variable averaged over the April-May period. The quality of fit for our models (R2 value) ranged from 0.87 to 0.91. The model was formulated to capture the average monthly temperature effect, a key weather factor. We found that for high-elevation stands located at least 1000 ma.s.l., forest damage was predominantly influenced by May t...
We analysed the relationship between the amount of potential solar radiation and spruce bark beet... more We analysed the relationship between the amount of potential solar radiation and spruce bark beetle Ips typographus (L.) catches in pheromone traps in an unmanaged nature reserve in the Carpathians (middle Slovakia region), from 2006 through 2009. This relationship was analysed under outbreak conditions. The number of traps varied in different years from 70 to 92. The traps were installed in spruce-forest-dominated stands affected by a windstorm in 2004. A GPS device was used to mark the position of the pheromone traps. The potential solar radiation was calculated with GIS tools for three different time periods in each year: with entire year, for main flight season of the spruce bark beetle and the spring swarming period. The relationship between the amount of potential solar radiation and the spruce bark beetle catches was statistically significant for each year and each time period except for the spring warming in 2007, when the pheromone traps were not set up on time.
Abstract To better understand the initiation and severity of tree mortality caused by the spruce ... more Abstract To better understand the initiation and severity of tree mortality caused by the spruce bark beetle (Ips typographus (L.)) during an outbreak, we analysed the entire course of an outbreak from 1990 to 2000 in the Tatra Mountains (Western Carpathians, Central Europe). This time period represents the last complete bark beetle gradation in this area. We distinguished three outbreak phases: the incipient epidemic, epidemic and post-epidemic stages. The sampling unit was the forest subcompartment. We analysed a total of 315 forest subcompartments over more than 2000 ha. We investigated the influence of 11 environmental and stand variables on two processes in different phases of the outbreak: the initiation and the severity of spruce mortality. We used factor analysis, discriminant analysis, multiple linear regressions and boosted regression trees for the statistical analyses. The results showed that the roles of host and site factors in the initiation and severity of spruce mortality caused by the spruce bark beetle differed during the outbreak according to the exploitation of available host resources. The initiation of tree mortality was primarily related to host factors, and the severity of mortality was dependent on host size and insolation.
The interception process in subalpine Norway spruce stands plays an important role in the distrib... more The interception process in subalpine Norway spruce stands plays an important role in the distribution of throughfall. The natural mountain spruce forest where our measurements of throughfall and gross precipitation were carried out, is located on the tree line at an elevation of 1,420 m a.s.l. in the Western Tatra Mountains (Slovakia, Central Europe). This paper presents an evaluation of the interception process in a natural mature spruce stand during the growing season from May to October in 2018–2020. We also analyzed the daily precipitation events within each growing season and assigned to them individual synoptic types. The amount and distribution of precipitation during the growing season plays an important role in the precipitation-interception process, which confirming the evaluation of individual synoptic situations. During the monitored growing seasons, precipitation was normal (2018), sub-normal (2019) and above-normal (2020) in comparison with long-term precipitation (19...
Intra-seasonal growth responses of co-occurring European beech (Fagus sylvatica L.) and Norway sp... more Intra-seasonal growth responses of co-occurring European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) to weather variability in montane forests can provide useful information on their future growth trends. To improve growth predictions, we aimed to identify (i) the main seasonal windows during which weather variability influences tree-ring growth, (ii) species-specific differences in the response to weather fluctuations, and (iii) teleconnections to remote sites in the Western Carpathians. We monitored intra-seasonal growth dynamics based on proxies extracted growth signals detected by high-resolution dendrometers in the transition zone between the beech and spruce altitudinal belt. Over 12 consecutive seasons in the natural montane forest (1350 m a.s.l.), the main part of spruce (68% to 10 July) and beech (95% to 26 August) annual increment was under the prevailing influence of temperature. After this, precipitation pattern (regarding spruce) and day lengt...
Eastern Palearctic conifers are subject to frequent bark beetle outbreaks. However, neither the s... more Eastern Palearctic conifers are subject to frequent bark beetle outbreaks. However, neither the species responsible nor the semiochemicals guiding these attacks are well understood. Two high-mountain Ips species on Qinghai spruce, Picea crassifolia, I. shangrila and I. nitidus, are typical in this regard. Six synthetic candidate pheromone components that we earlier identified from hindguts of unmated males of these two Ips species were tested for field activity in Qinghai province, P. R. China. For I. nitidus, racemic ipsdienol ((±)-Id) could replace the naturally-produced blend of enantiomers containing 74 % (-)-(S)-Id (74:26 S:R), in attractive ternary or binary blends. In contrast, sympatric I. shangrila were attracted mainly to blends including Id of opposite chirality, 97 %-(+)-(R)-Id. Of the verbenols, (-)-trans-verbenol was inactive for I. nitidus or inhibitory for I. shangrila, but (-)-cis-verbenol (cV) was a key component of the pheromone in both species. Two fully factorial experiments demonstrated that (±)-Id, cV, and 2-methyl-3-buten-2-ol (MB) are components of the aggregation pheromone of I. nitidus, whereas only (+)-Id and cV are essential components of the aggregation pheromone of I. shangrila. While MB is not necessary for attraction of I. shangrila, it is an active antagonist and likely functions in species isolation. A review of the pheromone production and responses in Palearctic Ips and Pseudoips showed that cV is more common than methylbutenols, and both elicit qualitatively variable responses. Ipsdienol is the most common component with variable chirality, and is a necessary, but often not sufficient, factor for determining pheromone specificity.
Exploitation of natural forests forms expanding frontiers. Simultaneously, protected area frontie... more Exploitation of natural forests forms expanding frontiers. Simultaneously, protected area frontiers aim at maintaining functional habitat networks. To assess net effects of these frontiers, we examined 16 case study areas on five continents. We (1) mapped protected area instruments, (2) assessed their effectiveness, (3) mapped policy implementation tools, and (4) effects on protected areas originating from their surroundings. Results are given as follows: (1) conservation instruments covered 3–77%, (2) effectiveness of habitat networks depended on representativeness, habitat quality, functional connectivity, resource extraction in protected areas, time for landscape restoration, “paper parks”, “fortress conservation”, and data access, (3) regulatory policy instruments dominated over economic and informational, (4) negative matrix effects dominated over positive ones (protective forests, buffer zones, inaccessibility), which were restricted to former USSR and Costa Rica. Despite evid...
Research Highlights: Bark beetles are important agents of disturbance regimes in temperate forest... more Research Highlights: Bark beetles are important agents of disturbance regimes in temperate forests, and specifically in a connected wind-bark beetle disturbance system. Large-scale windthrows trigger population growth of the European spruce bark beetle (Ips typographus L.) from endemic to epidemic levels, thereby allowing the killing of Norway spruce trees over several consecutive years. Background and Objectives: There is a lack of evidence to differentiate how outbreaks are promoted by the effects of environmental variables versus beetle preferences of trees from endemic to outbreak. However, little is known about how individual downed-tree characteristics and local conditions such as tree orientation and solar radiation affect beetle colonization of downed trees. Materials and Methods: To answer this question, we investigated the infestation rates and determined tree death categories (uprooted, broken, and stump) in wind-damaged areas in Western Tatra Mts. in Carpathians (Slovaki...
In recent decades, Norway spruce (Picea abies L. Karst.) forests of the High Tatra Mountains have... more In recent decades, Norway spruce (Picea abies L. Karst.) forests of the High Tatra Mountains have suffered unprecedented tree mortality caused by European spruce bark beetle (Ips typographus L.). Analysis of the spatiotemporal pattern of bark beetle outbreaks across the landscape in consecutive years can provide new insights into the population dynamics of tree-killing insects. A bark beetle outbreak occurred in the High Tatra Mountains after a storm damaged more than 10,000 ha of forests in 2004. We combined yearly Landsat-derived bark beetle infestation spots from 2006 to 2014 and meteorological data to identify the susceptibility of forest stands to beetle infestation. We found that digital elevation model (DEM)-derived potential radiation loads predicted beetle infestation, especially in the peak phase of beetle epidemic. Moreover, spots attacked at the beginning of our study period had higher values of received solar radiation than spots at the end of the study period, indicati...
Forest disturbances are intensifying globally, yet regional drivers of these dynamics remain poor... more Forest disturbances are intensifying globally, yet regional drivers of these dynamics remain poorly understood. We investigated recent disturbance intensities in Norway spruce (Picea abies L.) forests in Slovakia (Central Europe) with different management objectives in 2000–2017 based on Landsat imagery. We focused on 122 strict reserves without any management, their actively managed surroundings (500 m and 2000 m buffers), and managed production forests beyond the buffer areas. We used generalized additive mixed models to test for differences in temporal trends of disturbance intensity among these management categories. We found that disturbance intensity was increasing in all management categories during the studied period. The increase was more pronounced in the managed forests (compound annual disturbance rate 1.76% year−1) and the 2000 m buffer (2.21% year−1) than in the strict reserves (0.58% year−1). The predicted cumulative disturbance during the 18-year period was 9.9% in t...
The aim of this study was to develop methods for constructing a simple model describing tree mort... more The aim of this study was to develop methods for constructing a simple model describing tree mortality caused by Ips typographus L. using a minimum number of variables. We developed a model for areas spanning natural mountain forests in the Tatra National Park (Slovakia) and the Šumava National Park (Czech Republic), and in managed Czech forests located in four areas varying in environmental conditions. The model describes the time series of tree mortality dynamics caused by I.typographus using two submodels: a long-term dynamics submodel, and a short-term dynamics autoregressive distributed lag(ADL) model incorporating a two year delay and temperature variable averaged over the April-May period. The quality of fit for our models (R2 value) ranged from 0.87 to 0.91. The model was formulated to capture the average monthly temperature effect, a key weather factor. We found that for high-elevation stands located at least 1000 ma.s.l., forest damage was predominantly influenced by May t...
We analysed the relationship between the amount of potential solar radiation and spruce bark beet... more We analysed the relationship between the amount of potential solar radiation and spruce bark beetle Ips typographus (L.) catches in pheromone traps in an unmanaged nature reserve in the Carpathians (middle Slovakia region), from 2006 through 2009. This relationship was analysed under outbreak conditions. The number of traps varied in different years from 70 to 92. The traps were installed in spruce-forest-dominated stands affected by a windstorm in 2004. A GPS device was used to mark the position of the pheromone traps. The potential solar radiation was calculated with GIS tools for three different time periods in each year: with entire year, for main flight season of the spruce bark beetle and the spring swarming period. The relationship between the amount of potential solar radiation and the spruce bark beetle catches was statistically significant for each year and each time period except for the spring warming in 2007, when the pheromone traps were not set up on time.
Abstract To better understand the initiation and severity of tree mortality caused by the spruce ... more Abstract To better understand the initiation and severity of tree mortality caused by the spruce bark beetle (Ips typographus (L.)) during an outbreak, we analysed the entire course of an outbreak from 1990 to 2000 in the Tatra Mountains (Western Carpathians, Central Europe). This time period represents the last complete bark beetle gradation in this area. We distinguished three outbreak phases: the incipient epidemic, epidemic and post-epidemic stages. The sampling unit was the forest subcompartment. We analysed a total of 315 forest subcompartments over more than 2000 ha. We investigated the influence of 11 environmental and stand variables on two processes in different phases of the outbreak: the initiation and the severity of spruce mortality. We used factor analysis, discriminant analysis, multiple linear regressions and boosted regression trees for the statistical analyses. The results showed that the roles of host and site factors in the initiation and severity of spruce mortality caused by the spruce bark beetle differed during the outbreak according to the exploitation of available host resources. The initiation of tree mortality was primarily related to host factors, and the severity of mortality was dependent on host size and insolation.
The interception process in subalpine Norway spruce stands plays an important role in the distrib... more The interception process in subalpine Norway spruce stands plays an important role in the distribution of throughfall. The natural mountain spruce forest where our measurements of throughfall and gross precipitation were carried out, is located on the tree line at an elevation of 1,420 m a.s.l. in the Western Tatra Mountains (Slovakia, Central Europe). This paper presents an evaluation of the interception process in a natural mature spruce stand during the growing season from May to October in 2018–2020. We also analyzed the daily precipitation events within each growing season and assigned to them individual synoptic types. The amount and distribution of precipitation during the growing season plays an important role in the precipitation-interception process, which confirming the evaluation of individual synoptic situations. During the monitored growing seasons, precipitation was normal (2018), sub-normal (2019) and above-normal (2020) in comparison with long-term precipitation (19...
Intra-seasonal growth responses of co-occurring European beech (Fagus sylvatica L.) and Norway sp... more Intra-seasonal growth responses of co-occurring European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) to weather variability in montane forests can provide useful information on their future growth trends. To improve growth predictions, we aimed to identify (i) the main seasonal windows during which weather variability influences tree-ring growth, (ii) species-specific differences in the response to weather fluctuations, and (iii) teleconnections to remote sites in the Western Carpathians. We monitored intra-seasonal growth dynamics based on proxies extracted growth signals detected by high-resolution dendrometers in the transition zone between the beech and spruce altitudinal belt. Over 12 consecutive seasons in the natural montane forest (1350 m a.s.l.), the main part of spruce (68% to 10 July) and beech (95% to 26 August) annual increment was under the prevailing influence of temperature. After this, precipitation pattern (regarding spruce) and day lengt...
Eastern Palearctic conifers are subject to frequent bark beetle outbreaks. However, neither the s... more Eastern Palearctic conifers are subject to frequent bark beetle outbreaks. However, neither the species responsible nor the semiochemicals guiding these attacks are well understood. Two high-mountain Ips species on Qinghai spruce, Picea crassifolia, I. shangrila and I. nitidus, are typical in this regard. Six synthetic candidate pheromone components that we earlier identified from hindguts of unmated males of these two Ips species were tested for field activity in Qinghai province, P. R. China. For I. nitidus, racemic ipsdienol ((±)-Id) could replace the naturally-produced blend of enantiomers containing 74 % (-)-(S)-Id (74:26 S:R), in attractive ternary or binary blends. In contrast, sympatric I. shangrila were attracted mainly to blends including Id of opposite chirality, 97 %-(+)-(R)-Id. Of the verbenols, (-)-trans-verbenol was inactive for I. nitidus or inhibitory for I. shangrila, but (-)-cis-verbenol (cV) was a key component of the pheromone in both species. Two fully factorial experiments demonstrated that (±)-Id, cV, and 2-methyl-3-buten-2-ol (MB) are components of the aggregation pheromone of I. nitidus, whereas only (+)-Id and cV are essential components of the aggregation pheromone of I. shangrila. While MB is not necessary for attraction of I. shangrila, it is an active antagonist and likely functions in species isolation. A review of the pheromone production and responses in Palearctic Ips and Pseudoips showed that cV is more common than methylbutenols, and both elicit qualitatively variable responses. Ipsdienol is the most common component with variable chirality, and is a necessary, but often not sufficient, factor for determining pheromone specificity.
Exploitation of natural forests forms expanding frontiers. Simultaneously, protected area frontie... more Exploitation of natural forests forms expanding frontiers. Simultaneously, protected area frontiers aim at maintaining functional habitat networks. To assess net effects of these frontiers, we examined 16 case study areas on five continents. We (1) mapped protected area instruments, (2) assessed their effectiveness, (3) mapped policy implementation tools, and (4) effects on protected areas originating from their surroundings. Results are given as follows: (1) conservation instruments covered 3–77%, (2) effectiveness of habitat networks depended on representativeness, habitat quality, functional connectivity, resource extraction in protected areas, time for landscape restoration, “paper parks”, “fortress conservation”, and data access, (3) regulatory policy instruments dominated over economic and informational, (4) negative matrix effects dominated over positive ones (protective forests, buffer zones, inaccessibility), which were restricted to former USSR and Costa Rica. Despite evid...
Research Highlights: Bark beetles are important agents of disturbance regimes in temperate forest... more Research Highlights: Bark beetles are important agents of disturbance regimes in temperate forests, and specifically in a connected wind-bark beetle disturbance system. Large-scale windthrows trigger population growth of the European spruce bark beetle (Ips typographus L.) from endemic to epidemic levels, thereby allowing the killing of Norway spruce trees over several consecutive years. Background and Objectives: There is a lack of evidence to differentiate how outbreaks are promoted by the effects of environmental variables versus beetle preferences of trees from endemic to outbreak. However, little is known about how individual downed-tree characteristics and local conditions such as tree orientation and solar radiation affect beetle colonization of downed trees. Materials and Methods: To answer this question, we investigated the infestation rates and determined tree death categories (uprooted, broken, and stump) in wind-damaged areas in Western Tatra Mts. in Carpathians (Slovaki...
In recent decades, Norway spruce (Picea abies L. Karst.) forests of the High Tatra Mountains have... more In recent decades, Norway spruce (Picea abies L. Karst.) forests of the High Tatra Mountains have suffered unprecedented tree mortality caused by European spruce bark beetle (Ips typographus L.). Analysis of the spatiotemporal pattern of bark beetle outbreaks across the landscape in consecutive years can provide new insights into the population dynamics of tree-killing insects. A bark beetle outbreak occurred in the High Tatra Mountains after a storm damaged more than 10,000 ha of forests in 2004. We combined yearly Landsat-derived bark beetle infestation spots from 2006 to 2014 and meteorological data to identify the susceptibility of forest stands to beetle infestation. We found that digital elevation model (DEM)-derived potential radiation loads predicted beetle infestation, especially in the peak phase of beetle epidemic. Moreover, spots attacked at the beginning of our study period had higher values of received solar radiation than spots at the end of the study period, indicati...
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