Bark Beetle

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Rupert Seidl - One of the best experts on this subject based on the ideXlab platform.

  • How to manage windthrows in Central Europe to prevent Bark Beetle outbreaks
    2020
    Co-Authors: Laura Dobor, Tomáš Hlásny, Werner Rammer, Soňa Zimová, Rupert Seidl
    Abstract:

    <p>Bark Beetle (Ips typographus) epidemics in Europe are typically triggered by excessive availability of freshly dead trees and trees with compromised defense, which often occur after windstorms or droughts. Subsequently, enlarged Beetle populations migrate to the surrounding forests, which were not affected by the primary disturbance. Removal of windfelled trees (salvage or sanitation logging) is therefore a frequent management response to prevent the build-up of Bark Beetle populations. Yet, the effectivity of the removal remains poorly understood, particularly when the outbreaks are amplified by faster Beetle development cycles and reduced tree defense under climate change conditions.</p><p>Moreover, diverse ownership, management objectives and limited resources often restrict salvaging operations, and the final effect on Bark Beetle populations is thus even less clear. To better understand the interplay between climate, management, Bark Beetle populations, and host trees, we use the process-based forest landscape and disturbance model iLand. We studied differences between the removal of windfelled trees applied evenly across the landscape, focused on the vicinity of roads (scenario of limited logging resources) and concentrated in a contiguous block (scenario of spatially diversified management objectives) on a 16 050 ha forest landscape in Central Europe. We found that the removal of >80% of all windfelled trees is required to substantially reduce Bark Beetle disturbances. Focusing on the vicinity of roads created a “fire break effect” on Bark Beetle spread, and was moderately efficient in reducing landscape-scale Bark Beetle disturbance. Block treatments substantially reduced outbreaks in treated areas. Leaving parts of the landscape untreated (e.g., conservation areas) had no significant amplifying effect on outbreaks in managed areas. Our research suggests that the management of interacting disturbances from wind and Bark Beetles requires much more complex considerations than are currently practiced.</p>

  • spatial variability in tree regeneration after wildfire delays and dampens future Bark Beetle outbreaks
    Proceedings of the National Academy of Sciences of the United States of America, 2016
    Co-Authors: Rupert Seidl, Kenneth F. Raffa, Daniel C Donato, Monica G Turner
    Abstract:

    Climate change is altering the frequency and severity of forest disturbances such as wildfires and Bark Beetle outbreaks, thereby increasing the potential for sequential disturbances to interact. Interactions can amplify or dampen disturbances, yet the direction and magnitude of future disturbance interactions are difficult to anticipate because underlying mechanisms remain poorly understood. We tested how variability in postfire forest development affects future susceptibility to Bark Beetle outbreaks, focusing on mountain pine Beetle (Dendroctonus ponderosae) and Douglas-fir Beetle (Dendroctonus pseudotsugae) in forests regenerating from the large high-severity fires that affected Yellowstone National Park in Wyoming in 1988. We combined extensive field data on postfire tree regeneration with a well-tested simulation model to assess susceptibility to Bark Beetle outbreaks over 130 y of stand development. Despite originating from the same fire event, among-stand variation in forest structure was very high and remained considerable for over a century. Thus, simulated emergence of stands susceptible to Bark Beetles was not temporally synchronized but was protracted by several decades, compared with stand development from spatially homogeneous regeneration. Furthermore, because of fire-mediated variability in forest structure, the habitat connectivity required to support broad-scale outbreaks and amplifying cross-scale feedbacks did not develop until well into the second century after the initial burn. We conclude that variability in tree regeneration after disturbance can dampen and delay future disturbance by breaking spatiotemporal synchrony on the landscape. This highlights the importance of fostering landscape variability in the context of ecosystem management given changing disturbance regimes.

  • small Beetle large scale drivers how regional and landscape factors affect outbreaks of the european spruce Bark Beetle
    Journal of Applied Ecology, 2016
    Co-Authors: Rupert Seidl, Marco Heurich, Jörg Müller, Claus Bassler, Torsten Hothorn, Markus Kautz
    Abstract:

    1. Unprecedented Bark Beetle outbreaks have been observed for a variety of forest ecosystems recently, and damage is expected to further intensify as a consequence of climate change. In Central Europe, the response of ecosystem management to increasing infestation risk has hitherto focused largely on the stand level, while the contingency of outbreak dynamics on large-scale drivers remains poorly understood. 2. To investigate how factors beyond the local scale contribute to the infestation risk from Ips typographus (Col., Scol.), we analysed drivers across seven orders of magnitude in scale (from 103 to 1010 m2) over a 23-year period, focusing on the Bavarian Forest National Park. Time-discrete hazard modelling was used to account for local factors and temporal dependencies. Subsequently, beta regression was applied to determine the influence of regional and landscape factors, the latter characterized by means of graph theory. 3. We found that in addition to stand variables, large-scale drivers also strongly influenced Bark Beetle infestation risk. Outbreak waves were closely related to landscape-scale connectedness of both host and Beetle populations as well as to regional Bark Beetle infestation levels. Furthermore, regional summer drought was identified as an important trigger for infestation pulses. Large-scale synchrony and connectivity are thus key drivers of the recently observed Bark Beetle outbreak in the area. 4.Synthesis and applications. Our multiscale analysis provides evidence that the risk for biotic disturbances is highly dependent on drivers beyond the control of traditional stand-scale management. This finding highlights the importance of fostering the ability to cope with and recover from disturbance. It furthermore suggests that a stronger consideration of landscape and regional processes is needed to address changing disturbance regimes in ecosystem management.

  • impact of Bark Beetle ips typographus l disturbance on timber production and carbon sequestration in different management strategies under climate change
    Forest Ecology and Management, 2008
    Co-Authors: Rupert Seidl, Werner Rammer, Dietmar Jager, Manfred J. Lexer
    Abstract:

    Abstract The likely environmental changes throughout the next century have the potential to strongly alter forest disturbance regimes which may heavily affect forest functions as well as forest management. Forest stands already poorly adapted to current environmental conditions, such as secondary Norway spruce ( Picea abies (L.) Karst.) forests outside their natural range, are expected to be particularly prone to such risks. By means of a simulation study, a secondary Norway spruce forest management unit in Austria was studied under conditions of climatic change with regard to effects of Bark Beetle disturbance on timber production and carbon sequestration over a time period of 100 years. The modified patch model PICUS v1.41, including a submodule of Bark Beetle-induced tree mortality, was employed to assess four alternative management strategies: (a) Norway spruce age-class forestry, (b) Norway spruce continuous cover forestry, (c) conversion to mixed species stands, and (d) no management. Two sets of simulations were investigated, one without the consideration of biotic disturbances, the other including possible Bark Beetle damages. Simulations were conducted for a de-trended baseline climate (1961–1990) as well as for two transient climate change scenarios featuring a distinct increase in temperature. The main objectives were to: (i) estimate the effects of Bark Beetle damage on timber production and carbon (C) sequestration under climate change; (ii) assess the effects of disregarding Bark Beetle disturbance in the analysis. Results indicated a strong increase in Bark Beetle damage under climate change scenarios (up to +219% in terms of timber volume losses) compared to the baseline climate scenario. Furthermore, distinct differences were revealed between the studied management strategies, pointing at considerably lower amounts of salvage in the conversion strategy. In terms of C storage, increased biotic disturbances under climate change reduced C storage in the actively managed strategies (up to −41.0 tC ha −1 ) over the 100-year simulation period, whereas in the unmanaged control variant some scenarios even resulted in increased C sequestration due to a stand density effect. Comparing the simulation series with and without Bark Beetle disturbances the main findings were: (i) forest C storage was higher in all actively managed strategies under climate change, when biotic disturbances were disregarded (up to +31.6 tC ha −1 over 100 years); and (ii) in the undisturbed, unmanaged variant C sequestration was lower compared to the simulations with Bark Beetle disturbance (up to −69.9 tC ha −1 over 100 years). The study highlights the importance of including the full range of ecosystem-specific disturbances by isolating the effect of one important agent on timber production and C sequestration.

Jörg Müller - One of the best experts on this subject based on the ideXlab platform.

  • Bark Beetle Population Dynamics in the Anthropocene: Challenges and Solutions
    Trends in Ecology and Evolution, 2019
    Co-Authors: Peter H. W. Biedermann, Jörg Müller, Jean-claude Grégoire, Axel Gruppe, Jonas Hagge, Almuth Hammerbacher, Richard W. Hofstetter, Dineshkumar Kandasamy, Miroslav Kolarik, Martin Kostovčík
    Abstract:

    Tree-killing Bark Beetles are the most economically important insects in conifer forests worldwide. However, despite >200 years of research, the drivers of population eruptions and crashes are still not fully understood and the existing knowledge is thus insufficient to face the challenges posed by the Anthropocene. We critically analyze potential biotic and abiotic drivers of population dynamics of an exemplary species, the European spruce Bark Beetle (ESBB) (Ips typographus) and present a multivariate approach that integrates the many drivers governing this Bark Beetle system. We call for hypothesis-driven, large-scale collaborative research efforts to improve our understanding of the population dynamics of this and other Bark Beetle pests. Our approach can serve as a blueprint for tackling other eruptive forest insects.

  • functional response of lignicolous fungal guilds to Bark Beetle deforestation
    Ecological Indicators, 2016
    Co-Authors: Claus Bassler, Simon Thorn, Jörg Müller, Marc W Cadotte, Christoph Heibl, Johannes Bradtka, Hans Halbwachs
    Abstract:

    Abstract Conifer-dominated forests in the northern hemisphere are prone to large-scale natural disturbances, yet our understanding of their effects beyond changes in species diversity is limited. Bark Beetle disturbances provide dead wood for lignicolous fungal guilds and increase insolation but also desiccation. We investigated whether species richness of these guilds increases and functional diversity decreases after Bark Beetle disturbance, which would promote through habitat filtering the coexistence of species adapted to harsh conditions, i.e. light stress for lichens and substrate desiccation for wood-inhabiting fungi. We sampled epixylic and epiphytic lichens (primary producers) and wood-inhabiting fungi (mainly wood decomposers, some form ectomycorrhizas) in the Bohemian Forest (Long Term Ecological Research – LTER – Site Bavarian Forest National Park), an area in Central Europe most heavily affected by the Bark Beetle Ips typographus , on undisturbed plots and disturbed plots with spruce ( Picea abies ) dieback 8 years ago. We analysed species diversity, functional diversity (optimized by phylogeny), and functional compositions. Species richness of lichens but not that of wood-inhabiting fungi was higher on disturbed plots than on undisturbed plots. Community compositions of both guilds differed considerably on disturbed and undisturbed plots. On both types of plots, lichen communities were clustered according to functional diversity, which indicated habitat filtering, and fungal communities were overdispersed, which indicated competition. Disturbance increased the strength of these two patterns only slightly and was significant only for fungi. Single-trait analysis revealed changes in the functional composition; on disturbed plots, lichenous species with larger and more complex growth forms and fungi with large, perennial fruit bodies were favoured. Although the forest canopy changed tremendously because of the Bark Beetle disturbance, the most important driver of lichen and fungal diversity and mean trait assemblages seemed to be the enrichment of dead wood. The changes in insolation and moisture did not act as habitat filters for either guild. This indicated that the assembly patterns of lichen and fungal communities in coniferous forests are not affected by stand-replacing disturbances in contrast to the predictions for other disturbance regimes.

  • small Beetle large scale drivers how regional and landscape factors affect outbreaks of the european spruce Bark Beetle
    Journal of Applied Ecology, 2016
    Co-Authors: Rupert Seidl, Marco Heurich, Jörg Müller, Claus Bassler, Torsten Hothorn, Markus Kautz
    Abstract:

    1. Unprecedented Bark Beetle outbreaks have been observed for a variety of forest ecosystems recently, and damage is expected to further intensify as a consequence of climate change. In Central Europe, the response of ecosystem management to increasing infestation risk has hitherto focused largely on the stand level, while the contingency of outbreak dynamics on large-scale drivers remains poorly understood. 2. To investigate how factors beyond the local scale contribute to the infestation risk from Ips typographus (Col., Scol.), we analysed drivers across seven orders of magnitude in scale (from 103 to 1010 m2) over a 23-year period, focusing on the Bavarian Forest National Park. Time-discrete hazard modelling was used to account for local factors and temporal dependencies. Subsequently, beta regression was applied to determine the influence of regional and landscape factors, the latter characterized by means of graph theory. 3. We found that in addition to stand variables, large-scale drivers also strongly influenced Bark Beetle infestation risk. Outbreak waves were closely related to landscape-scale connectedness of both host and Beetle populations as well as to regional Bark Beetle infestation levels. Furthermore, regional summer drought was identified as an important trigger for infestation pulses. Large-scale synchrony and connectivity are thus key drivers of the recently observed Bark Beetle outbreak in the area. 4.Synthesis and applications. Our multiscale analysis provides evidence that the risk for biotic disturbances is highly dependent on drivers beyond the control of traditional stand-scale management. This finding highlights the importance of fostering the ability to cope with and recover from disturbance. It furthermore suggests that a stronger consideration of landscape and regional processes is needed to address changing disturbance regimes in ecosystem management.

  • the european spruce Bark Beetle ips typographus in a national park from pest to keystone species
    Biodiversity and Conservation, 2008
    Co-Authors: Jörg Müller, Heinz Busler, Martin Gosner, Thomas Rettelbach, Peter Duelli
    Abstract:

    The influence of natural disturbance on biodiversity is poorly known in the intensively cultivated landscape of Europe. As an example of insect disturbance we studied effects of gaps generated by outbreaks of the spruce Bark Beetle (Ips typographus) on biodiversity in the area of the National Park “Bavarian Forest” and compared them with openings (e.g. meadows) created by humans in these forests. Insects were sampled using flight interception traps across twelve ecotones between edges of closed forest, six Bark Beetle gaps and six meadows. The diversity and species density of true bugs and of bees/wasps increased significantly from the closed stand to the edge, and continued to increase inside the openings at interior and exterior edges. Species density in saproxylic Beetles also increased significantly from closed forest to opening, but only across ecotones including Bark Beetle gaps. Similarly, the number of critically endangered saproxylic Beetles increased significantly in Bark Beetle gaps. Using indicator species analysis a total of 60 species were identified as possessing a statistically significant value indicating preference for one of the habitat types along the ecotones: 29 of them preferred gaps, 24 preferred meadows, three were characteristic for edges of meadows, three for edges of Bark Beetle gaps, but only one was typical of closed forest. Most of our results support the thesis that I. typographus fulfils the majority of criteria for a keystone species, particularly that of maintenance of biodiversity in forests. Our results emphasize the value for the study and conservation of insect diversity of the policy of non-interference with natural processes pursued in some protected areas. As a recommendation to forest management for increasing insect diversity even in commercial forest, we suggest that logging in recent gaps in medium aged mixed montane stands should aim at retention of a part of the dead wood. Planting should be avoided, to lengthen the important phase of sunlit conditions.

Lars Barring - One of the best experts on this subject based on the ideXlab platform.

  • spatio temporal impact of climate change on the activity and voltinism of the spruce Bark Beetle ips typographus
    Global Change Biology, 2009
    Co-Authors: Anna Maria Jönsson, Gustaf Appelberg, Susanne Harding, Lars Barring
    Abstract:

    The spruce Bark Beetle Ips typographus is one of the major insect pests of mature Norway spruce forests. In this study, a model describing the temperature-dependent thresholds for swarming activity and temperature requirement for development from egg to adult was driven by transient regional climate scenario data for Sweden, covering the period of 1961-2100 for three future climate change scenarios (SRES A2, A1B and B2). During the 20th century, the weather supported the production of one Bark Beetle generation per year, except in the north-western mountainous parts of Sweden where the climate conditions were too harsh. A warmer climate may sustain a viable population also in the mountainous part; however, the distributional range of I. typographus may be restricted by the migration speed of Norway spruce. Modelling suggests that an earlier timing of spring swarming and fulfilled development of the first generation will significantly increase the frequency of summer swarming. Model calculations suggest that the spruce Bark Beetle will be able to initiate a second generation in South Sweden during 50% of the years around the mid century. By the end of the century, when temperatures during the Bark Beetle activity period are projected to have increased by 2.4-3.8 degrees C, a second generation will be initiated in South Sweden in 63-81% of the years. The corresponding figures are 16-33% for Mid Sweden, and 1-6% for North Sweden. During the next decades, one to two generations per year are predicted in response to temperature, and the northern distribution limit for the second generation will vary. Our study addresses questions applicable to sustainable forest management, suggesting that adequate countermeasures require monitoring of regional differences in timing of swarming and development of I. typographus, and planning of control operations during summer periods with large populations of Bark Beetles.

Peter Duelli - One of the best experts on this subject based on the ideXlab platform.

  • Synchronous rise and fall of Bark Beetle and parasitoid populations in windthrow areas
    Agricultural and Forest Entomology, 2013
    Co-Authors: Beat Wermelinger, Martin K. Obrist, Hannes Baur, Oliver Jakoby, Peter Duelli
    Abstract:

    Windthrows in spruce forests provide a prime substrate for the population build-up of Bark Beetles. Until now, no information has been available on the population development of associated parasitoids. The development of Bark Beetle and parasitoid populations was monitored on cleared and uncleared windthrow areas for 4 years, corresponding to the second to fifth growing seasons after the storm. The population level of both groups quickly increased synchronously from the second to the third season, and gradually declined thereafter until the fifth growing season. The parasitoids showed no time lag. At the species level, the same pattern was found for the pest Ips typographus (L.) and its specific parasitoid Dinotiscus eupterus (Walk.). During the 4 years under study, a succession of different Bark Beetle and parasitoid species was found. Bark Beetles and parasitoids were more abundant on uncleared windthrow areas than on cleared areas, whereas predatory Beetles generally preferred the adjacent forest. Once the deteriorated phloem quality precludes further Bark Beetle development, no more Bark Beetle-relevant parasitoids are produced in windthrows.

  • the european spruce Bark Beetle ips typographus in a national park from pest to keystone species
    Biodiversity and Conservation, 2008
    Co-Authors: Jörg Müller, Heinz Busler, Martin Gosner, Thomas Rettelbach, Peter Duelli
    Abstract:

    The influence of natural disturbance on biodiversity is poorly known in the intensively cultivated landscape of Europe. As an example of insect disturbance we studied effects of gaps generated by outbreaks of the spruce Bark Beetle (Ips typographus) on biodiversity in the area of the National Park “Bavarian Forest” and compared them with openings (e.g. meadows) created by humans in these forests. Insects were sampled using flight interception traps across twelve ecotones between edges of closed forest, six Bark Beetle gaps and six meadows. The diversity and species density of true bugs and of bees/wasps increased significantly from the closed stand to the edge, and continued to increase inside the openings at interior and exterior edges. Species density in saproxylic Beetles also increased significantly from closed forest to opening, but only across ecotones including Bark Beetle gaps. Similarly, the number of critically endangered saproxylic Beetles increased significantly in Bark Beetle gaps. Using indicator species analysis a total of 60 species were identified as possessing a statistically significant value indicating preference for one of the habitat types along the ecotones: 29 of them preferred gaps, 24 preferred meadows, three were characteristic for edges of meadows, three for edges of Bark Beetle gaps, but only one was typical of closed forest. Most of our results support the thesis that I. typographus fulfils the majority of criteria for a keystone species, particularly that of maintenance of biodiversity in forests. Our results emphasize the value for the study and conservation of insect diversity of the policy of non-interference with natural processes pursued in some protected areas. As a recommendation to forest management for increasing insect diversity even in commercial forest, we suggest that logging in recent gaps in medium aged mixed montane stands should aim at retention of a part of the dead wood. Planting should be avoided, to lengthen the important phase of sunlit conditions.

Marco Heurich - One of the best experts on this subject based on the ideXlab platform.

  • sentinel 2 accurately maps green attack stage of european spruce Bark Beetle ips typographus l compared with landsat 8
    Remote Sensing in Ecology and Conservation, 2019
    Co-Authors: Haidi Abdullah, Marco Heurich, Roshanak Darvishzadeh, Andrew K Skidmore
    Abstract:

    Natural disturbances induced by insect outbreaks have increased in forestecosystems over the past decades. To minimize economic loss and prevent amass outbreak, early detection of Bark Beetle green attack–a period when treeshave yet to show visual signs of infestation stress–is therefore crucial to effec-tive and timely forest management. In this study, we evaluated the ability ofspectral vegetation indices extracted from Landsat-8 and Sentinel-2 imagery tomap Bark Beetle green attack using principal component analysis (PCA) andpartial least square discriminate analysis (PLS-DA). A recent infestation mapproduced through visual interpretation of high-resolution aerial photographsvalidated the final infestation output maps. Leaf spectral measurements along-side total chlorophyll and nitrogen concentration, leaf water content and leafdry matter content were measured to assess the impact of Bark Beetle greenattack on foliar properties. We observed that the majority of spectral vegetationindices (SVIs) calculated from Sentinel-2, particularly red-edge dependentindices (NDRE 2 and 3) and water-related indices (SR-SWIR, NDWI, DSWIand LWCI), were able to discriminate healthy from infested plots. In contrast,only the water-related indices (NDWI, DSWI and RDI) from Landsat-8 wereable to discriminate between healthy and infested plots efficiently. The totalnumber of pixels identified as harboring a green attack that matched withground truth data (aerial photography) was higher for Sentinel-2 (67%) thanfor Landsat-8 (36%) SVIs, indicating the elevated sensitivity of Sentinel-2 ima-gery to changes induced by Bark Beetle green attack. We also determined thatfoliar chlorophyll and leaf water content were significantly higher (P<0.05) inhealthy trees than in green-attacked trees. Our study highlights the potential ofSentinel-2 data for the early detection of Bark Beetle infestations and the pro-duction of reliable infestation maps at the green-attack stage.This study aims toevaluate the ability of different spectral vegetation indices from Sentinel-2 andLandsat-8 imagery to map and detect Bark Beetle infestation at the green-attackstage. We observed that the majority of Spectral Vegetation Indices (SVIs) cal-culated from Sentinel-2 were able to discriminate healthy from infested plots.In contrast, only the water-related indices (NDWI, DSWI, and RDI) fromLandsat-8 were able to discriminate between healthy and infested plots effi-ciently. The total number of pixels identified as harboring a green attack thatmatched with ground truth data (aerial photography) was higher for Sentinel-2(67%) than for Landsat-8 (36%) SVIs, indicating the elevated sensitivity of Sen-tinel-2 imagery to changes induced by Bark Beetle green attack. We also determined that foliar chlorophyll and leaf water content were significantlyhigher (P<0.05) in healthy trees than in green-attacked trees. Our study high-lights the potential of Sentinel-2 data for the early detection of Bark Beetleinfestations and the production of reliable infestation maps at the green-attackstage.

  • 3D Hyperspectral and Thermal Analysis of Forest Trees Focusing on Bark Beetle Infestation
    2018
    Co-Authors: Peter Hofmann, Martin Hais, Marco Heurich, Rainer Pöschl, Stefan Kunze, Milan Novak, Doležal Petr, Stanislav Grill, Markéta Davídková, Milo Prokýzek
    Abstract:

    Disturbances caused by Bark Beetles are a massive problem for forestry in the northern hemisphere. Especially the central part of the national parks Bavarian Forest (Germany) and umava (Czech Republic) are often affected by Bark Beetle infestations. Recently, an early stage detection of Bark Beetle infestation is only possible by terrestrial inspection, which is labor intensive and costly. Thus, effective methods allowing an early-stage detection of Bark Beetle infestation of larger areas are needed. The joint project BarkBeeDet aims at investigating the detection of trees infested by Bark Beetle at an early stage (green-attack-stage) using methods of UAV (Unmanned Air Vehicle)-based imaging with LiDAR, hyperspectral and thermal IR sensors. The data of the different sensors is used in conjunction for image analysis, whereas methods of 3D object-based image analysis are applied. The paper present outlines first results of imaging and 3D object-based image analysis and concludes the potential of this method for an effective detection of Bark Beetle infestation.

  • european spruce Bark Beetle ips typographus l green attack affects foliar reflectance and biochemical properties
    International Journal of Applied Earth Observation and Geoinformation, 2018
    Co-Authors: Roshanak Darvishzadeh, Haidi Abdullah, Andrew K Skidmore, T A Groen, Marco Heurich
    Abstract:

    Abstract The European spruce Bark Beetle Ips typographus, L. (hereafter Bark Beetle), causes major economic loss to the forest industry in Europe, especially in Norway Spruce ( Picea abies ). To minimise economic loss and preclude a mass outbreak, early detection of Bark Beetle infestation (so-called “green attack” stage – a period at which trees are yet to show visual signs of infestation stress) is, therefore, a crucial step in the management of Norway spruce stands. It is expected that a Bark Beetle infestation at the green attack stage affects a tree’s physiological and chemical status. However, the concurrent effect on key foliar biochemical such as foliar nitrogen and chlorophyll as well as spectral responses are not well documented in the literature. Therefore, in this study, the early detection of Bark Beetle green attacks is investigated by examining foliar biochemical and spectral properties (400–2000 nm). We also assessed whether Bark Beetle infestation affects the estimation accuracy of foliar biochemicals. An extensive field survey was conducted in the Bavarian Forest National Park (BFNP), Germany, in the early summer of 2015 to collect leaf samples from 120 healthy and green attacked trees. The spectra of the leaf samples were measured using an ASD FieldSpec3 equipped with an integrating sphere. Significant differences (p

  • small Beetle large scale drivers how regional and landscape factors affect outbreaks of the european spruce Bark Beetle
    Journal of Applied Ecology, 2016
    Co-Authors: Rupert Seidl, Marco Heurich, Jörg Müller, Claus Bassler, Torsten Hothorn, Markus Kautz
    Abstract:

    1. Unprecedented Bark Beetle outbreaks have been observed for a variety of forest ecosystems recently, and damage is expected to further intensify as a consequence of climate change. In Central Europe, the response of ecosystem management to increasing infestation risk has hitherto focused largely on the stand level, while the contingency of outbreak dynamics on large-scale drivers remains poorly understood. 2. To investigate how factors beyond the local scale contribute to the infestation risk from Ips typographus (Col., Scol.), we analysed drivers across seven orders of magnitude in scale (from 103 to 1010 m2) over a 23-year period, focusing on the Bavarian Forest National Park. Time-discrete hazard modelling was used to account for local factors and temporal dependencies. Subsequently, beta regression was applied to determine the influence of regional and landscape factors, the latter characterized by means of graph theory. 3. We found that in addition to stand variables, large-scale drivers also strongly influenced Bark Beetle infestation risk. Outbreak waves were closely related to landscape-scale connectedness of both host and Beetle populations as well as to regional Bark Beetle infestation levels. Furthermore, regional summer drought was identified as an important trigger for infestation pulses. Large-scale synchrony and connectivity are thus key drivers of the recently observed Bark Beetle outbreak in the area. 4.Synthesis and applications. Our multiscale analysis provides evidence that the risk for biotic disturbances is highly dependent on drivers beyond the control of traditional stand-scale management. This finding highlights the importance of fostering the ability to cope with and recover from disturbance. It furthermore suggests that a stronger consideration of landscape and regional processes is needed to address changing disturbance regimes in ecosystem management.