Wind and bark beetle disturbances have increased in recent decades, affecting Europe's coniferous forests with particular severity. Management fostering forest diversity and resilience is deemed to ...effectively mitigate disturbance impacts, yet its efficiency and interaction with other disturbance management measures remain unclear.
We focused on Central Europe, which has become one of the hotspots of recent disturbance changes. We used the iLand ecosystem model to understand the interplay between species composition of the forest, forest disturbance dynamics affected by climate change, and disturbance management. The tested measures included (a) active transformation of tree species composition toward site‐matching species; (b) intensive removal of windfelled trees, which can support the buildup of bark beetle populations; and (c) reduction of mature and vulnerable trees on the landscape via modified harvesting regimes.
We found that management systems aiming to sustain the dominance of Norway spruce in the forest are failing under climate change, and none of the measures applied could mitigate the disturbance impacts. Conversely, management systems fostering forest diversity substantially reduced the level of disturbance. Significant disturbance reduction has been achieved even without salvaging and rotation length reduction, which is beneficial for ecosystem recovery, carbon, and biodiversity.
Synthesis and applications: We conclude that climate change amplifies the contrast in vulnerability of monospecific and species‐diverse forests to wind and bark beetle disturbance. Whereas forests dominated by Norway spruce are not likely to be sustained in Central Europe under climate change, different management strategies can be applied in species‐diverse forests to reach the desired control over the disturbance dynamic. Our findings justify some unrealistic expectations about the options to control disturbance dynamics under climate change and highlight the importance of management that fosters forest diversity.
We contrasted disturbance patterns of a Central European mountain forest that undergoes an intense transformation of species composition against a forest, where management maintained the dominance of vulnerable Norway spruce. Our findings justify some unrealistic expectations about the options to control disturbance dynamics under climate change and highlight the importance of management that fosters forest diversity.
This study focused on bionomics of the ash bark beetle
i (Panzer 1779). The study area was at Jílové u Prahy in the Central Bohemian Region of the Czech Republic. In February 2014, three common ash (
...) trees were felled and
infestation was subsequently observed from March. Beetles were collected from 20 debarked logs and dissected under stereomicroscope, and their sex was determined. Five logs with bark beetles were placed into photoeclectors. Beetles that emerged were collected and put into the second photoeclector with fresh ash wood to determine whether they would establish the second generation. The analysis showed that each gallery system with a pair of bark beetles contained one male with only one female. If one adult of
was found in the gallery system, it was usually female. Therefore, possible polygamy of
was not confirmed in Central Bohemia. Maternal gallery length significantly correlated with the number of eggs laid per female. Offspring beetles did not establish the second generation, as only maturation feeding occurred in fresh wood.
The striped ambrosia beetles
and
are timber forest pests in the Palearctic region and North America. Because only a few pathogens are known for
species, the aim of this work was to determine the ...spectrum of pathogen species of
,
, and
.
species were collected in pheromone traps at nine localities in the Czech Republic, five localities in Poland, and one locality in Austria. In total, 2,439
, 171
, and 17
beetles were dissected and examined. Infection was found in only two of the 17 specimens of
and in only two of the 171 specimens of
; in all four cases, the parasites were nematodes. Parasitisation of
by nematodes was found in
at eight localities with a mean (
SE) parasitisation level of 8.1 ± 4.7%. A
sp. was detected in cells of the midgut epithelium of one
specimen, and
sp. was detected in the midgut lumen of two
specimens; no other pathogens were found in
. The low infection rates and the tendency for infection by nematodes can be explained by the monogamy of
spp. and their feeding on fungi in short galleries that are not connected to the galleries of conspecifics.
•Reduced forest rotation length can reduce wind and bark beetle disturbance.•Efficiency of this measure decreases under climate change.•Short-term collateral effects on forest carbon and biodiversity ...are severe.
Forest disturbance regimes are intensifying in many parts of the globe. In order to mitigate disturbance impacts a number of management responses have been proposed, yet their effectiveness in addressing changing disturbance regimes remains largely unknown. The strong positive relationship between forest age and the vulnerability to disturbances such as windthrows and bark beetle infestations suggests that a reduced rotation length can be a potent means for mitigating the impacts of natural disturbances. However, disturbance mitigation measures such as shortened rotation lengths (SRL) can also have undesired consequences on ecosystem services and biodiversity, which need to be considered in their application.
Here, we used the process-based landscape and disturbance model iLand to investigate the effects of SRL on the vulnerability of a 16,000 ha forest landscape in Central Europe to wind and bark beetle disturbances. We experimentally reduced the current rotation length (between 100 and 115 years) by up to −40% in 10% increments, and studied effects on disturbance dynamics under current and future climate conditions over a 200-year simulation period. Simultaneously, we quantified the collateral effects of SRL on forest carbon stocks and indicators of biodiversity. Shortening the rotation length by 40% decreased disturbances by 14%. This effect was strongly diminished under future climate change, reducing the mitigating effect of shortened rotation to <6%. Collateral effects were severe in the initial decades after implementation: Reducing the rotation length by 40% caused a spike in harvested timber volume (+92%), decreased total forest carbon storage by 6% and reduced the number of large trees on the landscape by 20%. The long-term effects of SRL were less pronounced. At the same time, SRL caused an increase in tree species diversity. Shortening rotation length can reduce the impact of wind and bark beetle disturbances, but the overall efficiency of the measure is limited and decreases under climate change. Given the potential for undesired collateral effects we conclude that a reduction of the rotation length is no panacea for managing increasing disturbances, and should be applied in combination with other management measures reducing risks and fostering resilience.
Windfelled Norway spruce (Picea abies) trees play a crucial role in triggering large-scale outbreaks of the European spruce bark beetle Ips typographus. Outbreak management therefore strives to ...remove windfelled trees to reduce the risk of outbreaks, a measure referred to as sanitation logging (SL). Although this practice has been traditionally applied, its efficiency in preventing outbreaks remains poorly understood. We used the landscape simulation model iLand to investigate the effects of different spatial configurations and intensities of SL of windfelled trees on the subsequent disturbance by bark beetles. We studied differences between SL 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). We focused on a 16 050 ha forest landscape in Central Europe. The removal of >80% of all windfelled trees is required to substantially reduce bark beetle disturbances. Focusing SL 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. Climate change increased bark beetle disturbances and reduced the effect of SL. Our results suggest that past outbreak management methods will not be sufficient to counteract climate-mediated increases in bark beetle disturbance.
•Removal of windfelled trees is often applied in Europe to prevent the build-up of bark beetle populations.•Low-to medium-intensity removal has no effect on bark beetle outbreaks.•Different spatial configurations of removal have different effects on bark beetle dynamics.•Climate change critically reduces the efficiency of removal.
Salvage logging is one of most frequently applied management responses to forest disturbances world‐wide. As forest disturbances are increasing, so too is the application of salvage logging, yet its ...effects on ecosystems remains incompletely understood. In the Norway spruce (Picea abies (L.) Karst.) forests of Europe, salvaging of windfelled trees is inter alia applied to reduce the risk of bark beetle outbreaks (mainly Ips typographus L.). By preventing further disturbances, salvage logging can conserve live tree carbon (C) in forest landscapes. At the same time salvage logging reduces C stocks in detrital pools via the extraction of disturbed trees, its net effect thus remains unclear.
We used the forest landscape model iLand to explore the effect of a wide range of salvaging intensities on (a) subsequent bark beetle outbreaks, and (b) landscape‐scale forest C stocks in a Norway spruce‐dominated production forest in Slovakia under past and future climatic conditions.
Climate change resulted in a two‐ to three‐fold increase in bark beetle disturbances throughout the 21st century in our simulations. We found that removing >95% of disturbed trees can effectively buffer the effect of increasing disturbances, dampening bark beetle infestations and increasing live tree C. Total ecosystem C followed a U‐shaped pattern over salvaging intensity, with highest values in no salvage and 100% salvage scenarios.
However, realistic rates of salvaging (<95% of disturbed trees detected and removed) had no significant effect on bark beetle dynamics and live tree C, and reduced the total ecosystem C stored in the landscape. Furthermore, the effect of reduced bark beetle disturbance under intensive salvaging was partly offset by increased wind disturbance.
Synthesis and applications. Clearing disturbed areas to prevent future disturbances from bark beetles and conserve live tree carbon should only be applied where very high salvaging rates are feasible (i.e. small and concentrated disturbances). Considering that changing disturbance regimes make high‐intensity salvaging increasingly challenging, alternative disturbance management approaches need to be developed.
Foreign Language Czech
Odstraňování napadených či poškozených stromů (tzv. nahodilé těžby) je nejrozšířenější reakcí na výskyt různých disturbancí v lesních ekosystémech. Klimatická změna vede k intenzívnějšímu vlivu disturbancí na lesy a je tedy zapotřebí očekávat i nárůst rozsahu a intenzity nahodilých těžeb. Ve smrkových porostech v Evropě se nahodilé (v tomto případě přesněji sanitární) těžby větrem poškozených stromů provádějí proto, aby se zabránilo náletu lýkožroutů na vhodný rozmnožovací materiál či snížil nárůst populace, která již polámané stromy obsadila. Pokud zabráníme přemnožením kůrovců, uchováme rovněž zásobu uhlíku v živých stromech. Na druhé straně, těžbami odstraňujeme část uhlíku uloženého v mrtvém dřevu. Výsledný efekt těchto dvou protichůdných procesů na celkovou uhlíkovou bilanci však není znám.
V této studii jsme pomocí ekosystémového modelu iLand hodnotili vliv různých intenzit odstraňování větrem poškozených stromů na (a) následné přemnožení kůrovce a (b) na celkovou zásobu uhlíku v ekosystému. Výzkum byl realizován v hospodářském lese s dominancí smrku (75%) s rozlohou 16 050 ha.
V důsledku změny klimatu došlo v průběhu 21. století k dvou až trojnásobnému nárůstů objemu stromů napadených kůrovcem. Odstranění více než 95% větrem poškozených stromů účinně zmírnilo intenzitu kůrovcových přemnožení a došlo tím ke zvýšení zásob uhlíku v živých stromech. Závislost celkové zásoby uhlíku v ekosystémů na různé intenzitě těžeb měla tvar U. Nejvyšší úrovně byly dosahovány při absenci těžeb (uhlík se více kumuluje v mrtvém dřevu) a při celkovém odstranění větrem poškozených stromů (kůrovec je potlačen a uhlík se kumuluje v živých stromech). Realistická intenzita sanitárních těžeb (detekce a odstranění <95% poškozených stromů) neměla na dynamiku kůrovce a zásobu uhlíku v živých stromech téměř žádný vliv, naopak způsobila pokles celkové zásoby uhlíku v ekosystému. Intenzivní prevence vzniku přemnožení kůrovce zároveň vyvolala v dlouhodobém horizontu nárůst poškození porostů větrem a částečně tak negovala snahu o prevenci disturbancí.
Z těchto výsledků vyplývá, že odstraňování větrem poškozených stromů s cílem prevence nebo potlačení přemnožení kůrovce a uchování zásob uhlíku má smysl realizovat pouze tehdy, pokud je možné dosáhnout velice vysokou intenzitu těžeb (např. při menších a soustředěných polomech). Protože s klimatickou změnou dochází k zesílení vlivu disturbancí a změně dlouhodobých disturbančních režimů, provádění vysokých intenzit sanitárních těžeb bude stále obtížnější. Je proto zapotřebí hledat alternativní způsoby managementu hospodářských lesů orientující se na podporu jejich přirozené rezilience.
Clearing disturbed areas to prevent future disturbances from bark beetles and conserve live tree carbon should only be applied where very high salvaging rates are feasible (i.e. small and concentrated disturbances). Considering that changing disturbance regimes make high‐intensity salvaging increasingly challenging, alternative disturbance management approaches need to be developed.
The microsporidium Larssoniella duplicati (Weiser, Holuša, Žižka, 2006) is a specific pathogen of the bark beetle Ips duplicatus (C.R. Sahlberg, 1836), which is a serious pest of Norway spruce (Picea ...abies (L.) H. Karst) in Europe. From 2011 to 2016, infection levels of L. duplicati and other pathogens in I. duplicatus populations were assessed along a gradient, ranging from areas in the north, where the beetle is native, to areas in the south, where the beetle has only recently invaded. The 21 study sites ranged in altitude from 229 to 1009 m a.s.l. We found that pathogen infection levels in I. duplicatus populations decreased from the native areas in the north to the new areas of beetle expansion in the south. We also found that pathogen level increased with altitude. The L. duplicati infection levels were not associated with the infection levels of other beetle natural enemies. The infection level decreased with the length of time of beetle establishment in an area. The infection level increased with the number of beetles trapped and dissected at a site.
The aim of this thesis is to describe how basic school pupils imagine their ideal English teacher. The thesis is divided into two parts - theoretical and empirical. The theoretical part discusses the ...teacher's personality, professional requirements, communication and interaction in the lesson, evaluation of pupils and the typology of teachers. It is also interested in the prestige, the causes of feminization of the teaching profession and the process of building up the authority. The final chapter analyses from different points of view whether an ideal English teacher really exists. The empirical part is based on a qualitative study. The pupils were asked to write an essay, called "How do you imagine the ideal teacher of a foreign language?". Their answers are analysed and compared with existing hypotheses. The results of the research also discover whether and how the pupils' ideas are different in relation to their age.
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