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2. Ecological factors affecting the recent Picea abies decline in Slovenia : the importance of bedrock type and forest naturalnessJanez Kermavnar, Lado Kutnar, Anže Martin Pintar, 2023, original scientific article Abstract: Norway spruce (Picea abies [L.] Karst.) has been at the centre of controversy for many decades. Recent evidence of its profound disturbance-induced damage and consequent stock depletions across forest landscapes in Europe has reinforced doubts regarding the sustainability and prospects of this tree species in the future. Like many other European countries, Slovenia has experienced significant Norway spruce mortality and a decrease in growing stock primarily as the result of several disturbance agents (bark beetle outbreaks, an ice storm, windthrows). We investigated a countrywide spruce growing stock decline based on data between 2010 and 2018. Particular focus was placed on identifying the main ecological drivers of this decline, namely geological conditions, climatic parameters, soil attributes, topographic factors and forest stand characteristics. The effects of potential predictors on the relative change (%) in spruce volume (m3 ha-1) during the period 2010-2018 were analysed with Generalized Additive Models. Based on a national dataset including forest compartments (n = 6355) with a spruce growing stock decline > 10%, we found mixed support for ecology-based hypotheses. While spruce decline responded to bedrock type as predicted (i.e., greater relative decline in carbonate compared to silicate compartments), higher forest naturalness (preservation of tree species composition) was not associated with a lower decline. Spruce decline was amplified by higher potential evapotranspiration and soil clay content but showed a strong negative relationship with spruce proportion in the year 2010. General trends along the gradients of other selected predictors (stoniness/rockiness and heat load index) were less pronounced. The results suggest that most of these ecological predictors interact with geology and forest naturalness in affecting Norway spruce decline. Our analysis reveals that bedrock type can play an important role due to its mitigating effects. However, forest naturalness is of secondary significance as intensified large-scale forest disturbances likely override its buffering potential. Keywords: Norway Spruce, bark beetle outbreaks, ice storm, soil-geology, relationship, tree species composition, Slovenia Published in DiRROS: 05.04.2023; Views: 966; Downloads: 328
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3. Climate change and disturbances will shape future temperate forests in the transition zone between Central and SE EuropeLado Kutnar, Janez Kermavnar, Anže Martin Pintar, 2021, original scientific article Abstract: It is expected that climate change as well as abiotic and anthropogenic disturbances will strongly influence temperate forests. Besides changes in the main climate variables, various disturbance factors may significantly worsen conditions for mesic Slovenian forests (SE Europe) dominated by European beech (Fagus sylvatica), Norway spruce (Picea abies) and European silver fir (Abies alba). In Slovenia, the climate has warmed in recent decades, with an average annual rate of increase of about 0.4°C per decade or even more than 0.5°C per decade in summer. In addition, disturbances have caused considerable damage to trees in the most extensive forest types in Slovenia, starting with a widespread ice storm in 2014, followed by bark beetle outbreaks, windthrows and salvage logging interventions. After 2014, salvage logging increased from about one third to two thirds of the total annual felling. Over the last two decades, we have observed a decline in Norway spruce growing stock, with the highest rate of decrease in areas below 500 m a.s.l., and an increasing trend for European beech. Overall, the three dominant species (beech, spruce, silver fir), which together account for more than 70% of the total growing stock, have shown a declining trend over the last 20 years. The patterns observed are broadly consistent with earlier predictions developed for different climate change scenarios and with those reported in many other European countries. Adaptive forest management, which implements close-to-nature silviculture, has been traditionally practised in the region under study and has the potential to play an important role in reducing the risks associated with the impacts of climate change and disturbances in the future. Keywords: climate warming, disturbance factors, ice storm, bark beetle outbreaks, spruce decline, salvage logging, tree species composition, temperate forest, Slovenia Published in DiRROS: 03.01.2022; Views: 936; Downloads: 760
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4. Sensitivity analysis, calibration and validation of a phenology model for Pityogenes chalcographus (CHAPY)Nikica Ogris, Mitja Ferlan, Tine Hauptman, Roman Pavlin, Andreja Kavčič, Maja Jurc, Maarten De Groot, 2020, original scientific article Abstract: A phenology model of Pityogenes chalcographus was developed. The model quite accurately simulates the seasonal dynamics of P. chalcographus. Sensitivity analysis revealed the most influential parameters. CHAPY was calibrated and validated for Slovenia. Development of the model revealed several knowledge gaps. Keywords: six-toothed spruce bark beetle, insect outbreak, population dynamics, voltinism, ecological modelling, pheromone trap, trap tree, monitoring Published in DiRROS: 03.06.2020; Views: 2270; Downloads: 1295
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5. Calculation procedure for RITY-A phenology model of Ips typographusNikica Ogris, 2020, original scientific article Abstract: The RITY-2 phenology model was developed for the spatiotemporal simulation of the seasonal development of European spruce bark beetle, Ips typographus . RITY-2 is based on the PHENIPS model and was developed through improving PHENIPS with innovative approaches and calibrating and validating it for Slovenia. RITY-2 predictions are based on air temperatures from Integrated Nowcasting through a Comprehensive Analysis (INCA) system, which is used to calculate the effective bark temperature for beetle development. In this paper we describe the calculation procedure for RITY-2. Keywords: European spruce bark beetle, phenology, ecological modelling, voltinism, population dynamics Published in DiRROS: 19.03.2020; Views: 1876; Downloads: 1176
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