The European spruce bark beetle (Ips typographus) is an insect species that causes significant damage to Norway spruce (Picea abies) forests across Europe. Infestation by bark beetles can profoundly impact forest ecosystems, affecting their structure and composition and affecting the carbon cycle and biodiversity, including a decrease in net primary productivity (NPP), a key indicator of forest health. The primary objective of this study is to enhance our understanding of the interplay among NPP, bark beetle infestation, land surface temperature (LST), and soil moisture content as key components influencing the effects of climate change-related events (e.g., drought) during and after a drought event in the Bavarian Forest National Park in southeastern Germany. Earth observation data, specifically Landsat-8 TIR and Sentinel-2, were used to retrieve LST and leaf area index (LAI), respectively. Furthermore, for the first time, we incorporated a time series of high-resolution (20 m) LAI as a remote sensing biodiversity product into a process-based ecological model (LPJ-GUESS) to accurately generate high-resolution (20 m) NPP products. The study found a gradual decline in NPP values over time due to drought, increased LST, low precipitation, and a high rate of bark beetle infestation. We observed significantly lower LST in healthy Norway spruce stands compared to those infested by bark beetles. Likewise, low soil moisture content was associated with minimal NPP value. Our results suggest synergistic effects between bark beetle infestations and elevated LST, leading to amplified reductions in NPP value. This study highlights the critical role of integrating high-resolution remote sensing data with

Extreme weather events are increasingly recognized as major stress factors for forest ecosystems, causing both immediate and long-term effects. This study focuses on the impacts experienced by the forests of Valdisotto, Valfurva, and Sondalo (28% of the total area is covered by forests) in Upper Valtellina (Italy) due to the Vaia storm that occurred in October 2018. To define the immediate impacts of Vaia, we assess the economic value of forest ecosystem services (ESs), particularly those provided by timber production and carbon sequestration, pre- and post-Vaia and during the emergency period. We used the market price method to assess the economic values of timber production and carbon sequestration, as these are considered to be marketable goods. Based on data processed from Sentinel-2 satellite images (with a spatial resolution of 10 m), our results show that, despite the reduction in forest area (-2.02%) and timber stock (-2.38%), the economic value of the timber production increased after Vaia due to higher timber prices (i.e., from a total of 124.97 million to 130.72 million). However, considering the whole emergency period (2019-2020), the total losses are equal to 5.10 million for Valdisotto, 0.32 million for Valfurva, and 0.43 million for Sondalo. Instead, an economic loss of 2.88% is experienced for carbon sequestration, with Valdisotto being the more affected municipality (-4.48% of the pre-Vaia economic value). In terms of long-term impacts, we discuss the enhanced impacts due to the spread of the bark beetle Ips typopgraphus.

Introduction As a result of climate change and bark beetle outbreaks in forests, extensive salvage, and sanitary cutting have been undertaken in Europe, resulting in many clear-cuts with coarse stumps. The populations of pine weevils (Hylobius abietis and Hylobius pinastri) are steadily increasing. A high abundance of pine weevils feeding on seedlings typically results in significant economic losses and prolongs the forest establishment period. However, information on these species spatial distribution and habitat selection patterns, necessary for assessing their harmfulness and subsequently accurately estimating their threat to reforested areas, is lacking. To determine which factors influence spatial selection patterns and seedling type preference, this study investigated which clear-cut factors increase pine weevil abundance and which seedling types (species and age) are the most preferred. Methods The experiment was carried out on 20 clear-cuts in the central Czech Republic. We evaluated soil moisture level, average stump distance and diameter, proportion of other conifers, and whether the stumps were mulched. We detected the abundance of pine weevils using pitfall traps. We determined the feeding scar intensity on the first 10 cm of seedling stems on commonly used seedlings for reforestation in central Europe: 1-year-old Scots pine (Pinus sylvestris), European larch (Larix decidua), and 3-year-old Norway spruce (Picea abies), with 1,200 seedlings in total. The individual seedling types alternated in rows. The results were evaluated using generalized linear mixed-effect models (GLMMs). As dependent variables we used total numbers of H. abietis and H. pinastri. The soil moisture level, mulching, proportion of other conifers, average stump diameter, and distance were considered independent variables. Results We found that Norway spruce was the least attractive to pine weevils. We found a higher abundance of H. abietis females in moist clear-cuts, confirming that dry clear-cuts are less suitable for oviposition. Conclusion According to our findings, if foresters want to plant coniferous seedlings, it seems that planting older spruce is a better option than planting larch and pine. These findings provide valuable insights for forest management and reforestation strategies, equipping foresters with the knowledge to mitigate the threat of pine weevils and ensure successful forest establishment.

The frequent outbreaks of European spruce bark beetle Ips typographus (L.) have destroyed huge amounts of Norway spruce Picea abies (L.) forests in central and Northern Europe. Identifying the risk factors and estimating the damage level is important for strategic damage control. The risk factors of forest damage by spruce bark beetles have mostly been analyzed on the landscape scale, while the in-stand risk factors have been less investigated. This study aims at exploring the local-scale risk factors in a flat area with spruce-dominated forest in southern Sweden. The investigated factors include four abiotic factors, i.e., soil wetness, solar radiation, slope gradient, and aspect, and three biotic factors, i.e., the number of deciduous trees and trees that died from attacks in previous years that remained (TreesLeft) and removed (TreesRemoved) from the forest stand. We put up 24 pheromone bags in six stands attacked by bark beetle in the previous years, resulting in different numbers of infested trees in each plot. We explored in which microenvironment a pheromone bag resulted in more colonization, the impact radius of each factor, and the necessary factors for a risk model. The environmental factors were obtained from remote sensing-based products and images. A generalized linear model (GLM) was used with the environmental factors as the explanatory variables and the damage levels as the response variables, i.e., the number of attacked trees for the plot scale, and healthy/infested for the single-tree scale. Using 50 m and 15 m radius of the environmental factors resulted in the best fit for the model at plot and individual tree scales, respectively. At those radii, the damage risk increased both at plot and individual tree level when spruce were surrounded by more deciduous trees, surrounded by dead trees that had been removed from the forest, and spruces located at the north and east slopes (315 degrees-135 degrees of aspect, > 2 degrees slope). Soil wetness, solar radiation, and remaining standing dead trees in the surrounding did not significantly impact the damage level in the microenvironment of the study area. The GLM risk model yielded an overall accuracy of 0.69 in predicting individual trees being infested or healthy. Our efforts to investigate the risk factors provide a context for wall-to-wall mapping in-stand infestation risks, using remote sensing-based data.

Bark beetle outbreaks are a significant cause of high tree mortality rates, dramatically impacting the resilience of forests. Understanding the triggers and impacts of these outbreaks is critical for effective forest management strategies. In this context, we studied windfall and bark beetle outbreaks in the period 2015-2021 in the southern part of Kurilskiy Nature Reserve, North Pacific Ocean region. Massive bark beetle outbreaks on Kunashir Island were not previously studied. The dominant tree species are Yezo spruce (Picea jezoensis) and Sakhalin fir (Abies sachalinensis), which collectively form spruce -fir forests on Kunashir Island. Glehn spruce (Picea glehnii), although less common on the island, forms pure spruce forests. Typically, spruce bark beetle (Ips typographus L.) attacks Yezo and Glehn spruce, and fir bark beetle (Polygraphus proximus) attacks Sakhalin fir. Significant tree mortality was observed in the aftermath of a substantial bark beetle outbreak, induced by gale -force winds. The total disturbance area was 620.5 ha, which is about 4% of the study area, 72% of the windfall area, and 28% of the bark beetle -infested area. Utilising a forest loss dataset (Global Forest Change dataset) and Sentinel 2 imagery, we identified windfall areas and standing tree mortality through unsupervised classification, accompanied by field sampling. Subsequently, the authors analysed the main drivers of disturbances caused by wind and bark beetle outbreaks using datasets combined with forest inventory data. Field data showed a pattern of tree infestation by both bark beetle species at the tree level, and the potential infestation of Sakhalin fir by the spruce bark beetle. We used boosted regression tree (BRT) models to analyse the main drivers using the presence and severity of wind damage and bark beetle outbreaks by phases. As predictors, we used a set of forest characteristics (tree species percentage, height, diameter of trunk, age, growth class) and environmental characteristics (slope, elevation, potential solar radiation, soil pH). The bark beetle outbreak was split into two phases: the first phase (2017-2019) involved the transition of bark beetles from colonised downed trees to standing trees, and the second phase (2020-2021) occurred during the spreading of beetles in standing trees. Stand tree characteristics were of greater significance for the likelihood of a bark beetle outbreak than environmental characteristics, across both phases for the southern part of the reserve. The percentage and the age of Glehn spruce and Yezo spruce were the main influencing factors for the presence and severity of an outbreak.

Invasions of dendrophagous insects pose major threats to forest ecosystems and to the timber industry. The alien species bark beetle Polygraphus proximus Blandf. of Far Eastern origin has caused Siberian fir dieback in vast areas within several regions of Russia. Rapid spread of the pest and its outbreaks raise the issue of preserving the most important functions, including carbon sequestration, by the damaged forests. In this study, monitoring of carbon pool dynamics was carried out during 2012-2023 on four sample plots showing various degrees of damage in the southern taiga zone of Western Siberia in the Larinsky Landscape Reserve. Dynamics of the forest stands' vitality were reflected in a rapid decline of the number of viable trees and an increase in amounts of deadwood, debris, and soil composition, resulting in a transformation of the natural biological carbon cycle in the native dark coniferous ecosystems.

Disturbances caused by the European spruce bark beetle (SBB; Ips typographus L.) on Norway spruce ( Picea abies (L.) H. Karst.), have increased immensely across Central and Northern Europe, and are expected to increase further as a result of climate change. While this trend has been noted in Finland, so far limited research has been published. To support proper SBB risk management in Finland, we compared stand properties between salvage loggings due to SBB damage during 2012-2020 (4691 cases) and spruce stands free of SBB damage. Also, we explored the role of landscape attributes as drivers of SBB damage. We considered the forest stand attributes of site fertility class, stand development class, soil type, stand mean diameter at breast height and mean stand age. Considered forest landscape attributes were the distance from SBB-damaged stands to the closest clear-cut, to previous -year SBB-damaged stands and to the previous -year wind -damaged stand. We used nationwide forest logging and forest stock data, and analysed forest stand attributes using Chi -squared and Mann -Whitney U tests and landscape attributes using generalised linear mixed models. Based on our findings, the SBB didn't damage stands randomly, but prevailed in mature stands (high age and high mean diameter at breast height), in herb -rich heath forest site types and in semi -coarse or coarse heath forest soil soils. We found correlation between the landscape variables and the number of salvage loggings, with a higher number of loggings due to SBB damage close to clear -cuts. Our results help to find risk areas of SBB damage.