Ulrich Kohnle - Academia.edu (original) (raw)

Papers by Ulrich Kohnle

Annals of forest science, 2010

Existing growth and yield plots of pure and mixed stands of Norway spruce (Picea abies (L.) H. Ka... more Existing growth and yield plots of pure and mixed stands of Norway spruce (Picea abies (L.) H. Karst.) and European beech (Fagus sylvatica L.) were aggregated in order to unify the somewhat scattered sources of information currently available, as well as to develop a sound working hypothesis about mixing effects. The database contains information from 23 long-term plots, covering an ecological gradient from nutrient poor and dry to nutrient rich and moist sites throughout Central Europe. • An empirically formed interaction model showed, that depending on the site conditions, dry mass growth in mixed stands can range from −46% to +138 % of the growth yielded by a scaled combination of pure stands at equal mixing proportions. • Drawing from the interaction model, overyielding of the mixed stands appears to be triggered by two separate mechanisms. On poor sites, where significant overyielding is commonly found, facilitation by beech offsets nutrient-related growth limitations in spruce. In contrast, overyielding of mixed stands occurs less frequently on rich sites, and appears to be based on an admixture effect, with spruce reducing the severe intra-specific competition common in pure beech stands. • It was concluded that silviculture can accelerate growth of spruce by beech admixtures on poor sites, while growth of beech can be promoted by admixture of spruce, particularly on excellent sites.

Holz-Zentralblatt : unabhängiges Organ für die Forst- und Holzwirtschaft, 2018

Aus der Forschung sçå=rïÉ=pÅÜãáííGI=gçÜ~ååÉë=tÉääáåÖGI=dÉê~äÇ=hçÅÜGI bÅâÜ~êÇ=jÉäÅÜÉêGI=g~åJeÉååáå... more Aus der Forschung sçå=rïÉ=pÅÜãáííGI=gçÜ~ååÉë=tÉääáåÖGI=dÉê~äÇ=hçÅÜGI bÅâÜ~êÇ=jÉäÅÜÉêGI=g~åJeÉååáåÖ=_äçÜãGI=räêáÅÜ=hçÜåäÉGGI cê~åâ~=_êΩÅÜÉêíGG=ìåÇ=rÇç=e~åë=p~ìíÉêGG as natürliche Verbreitungsgebiet der Douglasie (Pseudotsuga menziesii (Mirb.) Franco) liegt im Westen Nordamerikas. Bei dieser Baumart werden zwei populationsgenetisch voneinander abweichende Formen unterschieden, die nach ihren Hauptvorkommensgebieten als Küstenbzw. Inlands-Douglasien bezeichnet werden. Beide wachsen in Waldgesellschaften mit Westlicher Hemlocktanne, Küstentanne, Küstenmammutbaum und Zucker-Kiefer. Für den Anbau in Mitteleuropa hat sich die Küsten-Douglasie bewährt, die aus dem pazifischen Nordwesten stammt und in der westkanadischen Provinz Britisch-Kolumbien sowie den US-Bundesstaaten Oregon, Washington und Kalifornien natürlich beheimatet ist. Die sehr gute Holzqualität der Douglasie bei gleichzeitig leichter Verarbeitbarkeit machten sie in Nordamerika zu

Schweizerische Zeitschrift Fur Forstwesen, Mar 1, 2021

Der erwartete Klimawandel macht die Douglasie (Pseudotsuga menziesii [Mirb.] Franco) zu einer vie... more Der erwartete Klimawandel macht die Douglasie (Pseudotsuga menziesii [Mirb.] Franco) zu einer vielversprechenden Option für die Waldbewirtschaftung in Mitteleuropa. Die Art ist resistenter gegenüber Trockenheit als zum Beispiel die Fichte, wächst sehr gut und liefert wertvolles Sägeholz mit überlegenen technischen Holzeigenschaften. Die über ein Jahrhundert vor allem in Frankreich und in Deutschland gesammelte Erfahrung in Forschung und Praxis hat substanzielles, evidenzbasiertes waldbauliches Wissen zur Bewirtschaftung der Douglasie in Europa geschaffen. Der Artikel hat zum Ziel, die wichtigsten Aspekte darzustellen. Während die mit relativ hohen Kosten verbundene Pflanzung bislang die gebräuchlichste Begründungstechnik in Europa war, wird das offensichtliche Potenzial der natürlichen Verjüngung mit grosser Wahrscheinlichkeit an Bedeutung gewinnen. Allerdings wird die Wurzelentwicklung junger Bäume sowohl durch Überschirmung als auch durch seitliche Konkurrenz negativ beeinflusst. Wenn die Douglasie unter Schirm verjüngt werden soll, muss die Dauer der Überschirmung kurz gehalten und die seitlichen Konkurrenten frühzeitig und entschlossen entfernt werden. Das Durchmesserwachstum lässt sich durch geeignete Pflanzabstände, Durchforstung und die Wahl der Produktionszeiträume gezielt steuern. Die Holzqualität kann durch die Auswahl von Z-Bäumen und eine Ästung verbessert werden. Um den Anteil an qualitativ minderwertigen schwachen Sortimenten klein zu halten, kann ein längerer Produktionszeitraum in Verbindung mit grösserem Zieldurchmesser als Bewirtschaftungsoption in Betracht gezogen werden. Allerdings sind längere Produktionszeiträume ausnahmslos mit höheren Risiken verbunden, insbesondere nimmt das Sturmschadenrisiko mit der Baumhöhe progressiv zu. Im Zusammenhang mit dem Risikomanagement und der Integration der nicht einheimischen Douglasie in naturnahe Bewirtschaftungssysteme sind die Begründung und die Bewirtschaftung von Mischbeständen von grosser Bedeutung.

Zeitschrift für Naturforschung C, Dec 1, 1988

Ipsenol, Ipsdienol, and £-myrcenol are male specific compounds of Ips schmutzenhoferi. Overall 46... more Ipsenol, Ipsdienol, and £-myrcenol are male specific compounds of Ips schmutzenhoferi. Overall 46 compounds could be identified from males and females. The diversity of oxygenated terpenes is particularly high in males.

Agricultural and Forest Meteorology, May 1, 2017

The annual growth of the Finnish forests has doubled in less than a century but the reasons for t... more The annual growth of the Finnish forests has doubled in less than a century but the reasons for the increase have been a subject of much debate. Site index aggregates the mid-to long-term impacts of variable edaphic and climatic factors on site productivity and is an important characteristic with regard to the ongoing environmental changes. We quantified changes of site index in Finland over time by applying a new approach developed in our previous study in Germany. A large data base for Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and larch (Larix spp.) was available from the network of long-term growth and yield experiments in southern and central Finland. For all tree species, site indices fluctuated over time, i.e. they slightly decreased in the 1970s, followed by an increasing trend in the 1980s and a decline again in the 1990s. Apparently, the only significant change was a change point indicated for Scots pine around the year 1944; however, indication was weak due to notable limitations of the database during the respective period. Interestingly, the result of this study in Finland differs from central Europe, where Norway spruce site productivity has displayed a considerable increase since the 1950s. Potentially, the low nitrogen deposition in Finland may be of major importance accounting for the divergent changes in site productivity between Finland and central Europe. Thus, the results indicate that a large share of the growth increase in the Finnish forests might actually be due to altered management.

Zeitschrift für Angewandte Entomologie, Aug 26, 2009

ABSTRACT Antennal olfactory and behavioral responses by sympatric ambrosia beetles, Trypodendron ... more ABSTRACT Antennal olfactory and behavioral responses by sympatric ambrosia beetles, Trypodendron lineatum, T. domesticum and T. signatum, to their aggregation pheromone lineatin was found to be specific to the (+)-enantiomer. The (-)-antipode was inactive thus showing no indication of synergistic or repellent effects. The results indicate that these closely related congenerics use an identical pheromonal signal and suggest that reproductive isolation is achieved by other mechanisms. Die Reaktion sympatrischer Trypodendron-Arten auf optisch aktives Lineatin: Elektroantennogramm und Freilandtest Die Nutzholzborkenkäfer Trypodendron lineatum, T. domesticum und T. signatum reagierten im Elektroantennogramm und an Lockstoff-Fallen nur auf die (+)-Enantiomere ihres Aggregations-pheromons Lineatin. Der (-)-Antipode zeigte weder fördernde noch hemmende Wirkung. Alle drei sympatrischen Trypodendron-Anen verwenden somit das gleiche Aggregationspheromon; die Artentrennung wird offenbar durch andere Mechanismen erreicht.

Naturwissenschaften, 1984

Zeitschrift für Angewandte Entomologie, Aug 26, 2009

Investigations on the aggregation pheromone of the mediterranean engraver beetle Ips (Orthotomicu... more Investigations on the aggregation pheromone of the mediterranean engraver beetle Ips (Orthotomicus) erosus Attempts were made to identify the aggregation pheromone produced by male I. erosus while initiating attack on Pinus inaster by gas chromatographic analyses of headspace gas obtained from the hindguts of male bee&. The chemical analysis and field tests in South African pine plantations indicate 2-methyl-6-merhylene-2,7-octadien-4-01 (ipsdienol) and 2-methyl-3-buten-2-01 to represent the major components of an aggregating principle that could be utilized in the surveillance of this world wide expanding insect pest.

Allgemeine Forst Und Jagdzeitung, 2014

Allgemeine Forst Und Jagdzeitung, 2009

Forest Ecology and Management, Jul 1, 2021

The maximum size-density relationship describes site carrying capacity, i.e., the maximum number ... more The maximum size-density relationship describes site carrying capacity, i.e., the maximum number of trees of a given size that can be stocked per unit area (self-thinning line). We analysed whether the self-thinning lines of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) have remained unchanged over time in South Germany, Norway and Finland, i.e., over a wide climatic gradient from Central Europe up to the Arctic circle. The analyses are based on long-term growth and yield experiments measured on individual tree basis over several decades, the oldest experiments established during the early 20th century. The stochastic frontier analysis was used to analyse changes in the species-specific self-thinning lines. The results show that the self-thinning lines have shifted upwards over time in all the regions. Thus, currently stands sustain higher stand densities than in the past. The increase of the maximum density for a given average stem size was more pronounced for pine than for spruce, but similar in all studied geographical regions. In addition, increasing site index was associated with increasing site carrying capacity for spruce and pine in all regions. The results imply that environmental changes have altered site properties in similar fashion across the whole study region. In practical forestry, increased site carrying capacity will reduce mortality and loss of growing stock.

Naturwissenschaften, Mar 1, 1991

Journal of Applied Entomology, Jan 12, 1993

Host selecting males of Ips mannsfeldi release (S)‐(+)‐ipsdienol, (S)‐(‐)‐ipsenol, amitinol and 2... more Host selecting males of Ips mannsfeldi release (S)‐(+)‐ipsdienol, (S)‐(‐)‐ipsenol, amitinol and 2‐methyl‐6‐methylene‐1,3E,7‐octatriene (“ipstriene”) as major beetle specific volatiles and obviously employ the terpene alcohols in a frass pheromone system. A vertex‐pronotal stridulatory organ is present in the females.ZusammenfassungDas Pheromonsystem des Schwarzkiefern‐Borkenkäfers Ips mannsfeldi (Wachtl) (Col., Scolytidae)Wirtswählende Ips mannsfeldi Männchen geben größere Mengen an (S)‐(+)‐Ipsdienol, (S)‐(‐)‐Ipsenol, Amitinol und 2‐Methyl‐6‐methylen‐1,3E,7‐octatrien (“Ipstrien”) als käferspezifische Duftstoffe beim Befall eines Wirtsbaumes ab. Die Terpenalkohole Ipsdienol und Ipsenol bilden als Synergisten ein Fraßpheromonsystem, das die Aggregation der Käfer an temporären Habitaten in geschwächten Wirtsbäumen auslöst. Elektronenmikroskopische Untersuchungen zeigen bei den Weibchen ein Stridulationsorgan vom Vertex‐Pronotal‐Typ, das bei den Männchen fehlt.

Zeitschrift für Angewandte Entomologie, Aug 26, 2009

Investigations of chemical communication systems in secondary bark beetles (Col., Scolytidae) The... more Investigations of chemical communication systems in secondary bark beetles (Col., Scolytidae) The chemical communication system of several secondary European bark beetles was investigated. The ash bark beetle, Leperisinus varius, responded in the field to ethanol‐baited traps in significant numbers. Male‐released exo‐brevicomin increased trap catches of L. varius while another male specific compound, 7‐methyl‐1,6‐dioxaspiro [4.5] decane, proved inhibitory. Hylurgops palliatus, a species colonizing Norway spruce was attracted to traps containing ethanol as a bait; spruce resin acted synergistically. For Dryocoetes autographus, another spruce bark beetle, females were shown to be the host selecting sex, suggesting this species to be monogynous. However, the males release endo‐ and exo‐brevicomin which attracted predominantely female D. autographus in the field. With endo‐brevicomin, only the (+)‐enantiomer elicited response of D. autographus while the antipode did not affect beetle response.In polygynous bark beetle species males are the host selecting sex and as a rule release the aggregating pheromone(s) which attract both males and females. Dispersal losses of hostsearching males are compensated through male polygyny. In contrast, some monogynous bark beetles such as D. autographus seem to balance the sex ratio during host colonization through sexual crossattractiveness of sex‐specific pheromones: Male and female beetles release different pheromone components attracting predominantely beetles of the opposite sex; a phenomenom characteristic for sex pheromones of Lepidoptera.Within associations of bark beetles colonizing Norway spruce investigated in this study, kairomonal effects of pheromones were common. E.g., the aggressive species Ips typographus and Pityogenes chalcographus were attracted to some extent to endo‐ or exo‐brevicomin, pheromone components of secondary D. autographus. In contrast, response of D. autographus to baited traps was inhibited when pheromone components of the aggressive species were added.ZusammenfassungDas Aggregationsverhalten verschiedener sekundärer Borkenkäfer wurde untersucht.Hylurgops palliatus: Duftstoffe des Wirts und Ethanol locken synergistisch.Leperisinus varius: Im Freiland locken Ethanol und das ♂‐spezifische exo‐Brevicomin; ein weiterer Duftstoff der ♂♂, 7‐Methyl‐1,6‐dioxaspiro [4.5] decan, ist ein Ablenkstoff.Dryocoetes autographus: Das (+)‐Isomer des ♂‐spezifischen endo‐Brevicomin lockt im Freiland zahlreiche Käfer, während der Antipode biologisch inaktiv ist. Die ♂♂ locken mit endo‐bzw. exo‐Brevicomin vorwiegend die ♀♀ an; die Lockwirksamkeit dieser Pheromone wird durch Ethanol und Terpene verstärkt.Die Anlockung der D. autographus‐♀♀ durch ♂‐spezifische Pheromone weist auf ein Aggregationsprinzip hin, das in dieser Arbeit diskutiert wird: das Prinzip der geschlechtsorientierten Anlockung; ♀♀ und/oder ♂♂ locken sich gegenseitig mit Pheromonen, die in Abgabe und Wirkung geschlechtsspezifisch sein können. Hierdurch gelingt es monogynen Arten, den Wirt in einem ausgewogenen Geschlechterverhältnis zu besiedeln, während andere Arten das Geschlechterverhältnis der angelockten Käfer durch die Polygynie der ♂ ausgleichen.Zwischen assoziierten Fichtenborkenkäfern treten zahlreiche kairomonale Effekte von Pheromonkomponenten auf. So werden beispielsweise die aggressiven Rindenbrüter Ips typographus bzw. Pityogenes chalcographus von endo‐ bzw. exo‐Brevicomin des sekundären D. autographus angelockt, während umgekehrt Pheromonkomponenten der beiden aggressiven Arten auf D. autographus ablenkend wirken.

Naturwissenschaften, May 1, 1986

Journal of Applied Entomology, Jan 12, 1986

... Acal Sci. Hungar. 9, 237-270. JEPPSON, LR; KEIFER, HH and BAKER, EW, 1975: Mites injurious to... more ... Acal Sci. Hungar. 9, 237-270. JEPPSON, LR; KEIFER, HH and BAKER, EW, 1975: Mites injurious to economic plants. Univ. of California Press, Berkeley, CA, 613 pp. ... Ph. D. Thesis. Univ. of Sofia, Bulgaria. ROIVAINEN, H., 1950: Erio hyid news from Sweden. Acta Entomol. Fenn. ...

Journal of Applied Entomology, Jan 12, 1988

Upon feeding in the bark of a host tree, Ips schmutzenhoferi males release major amounts of ipsen... more Upon feeding in the bark of a host tree, Ips schmutzenhoferi males release major amounts of ipsenol along with traces of ipsenone and ipsdienol. Racemic ipsenol proved attractive in laboratory and field bioassays. Field response of I. schmutzenhoferi was synergized by adding (S)‐cis‐verbenol to the bait material. Low concentrations of racemic ipsdienol seemed to enhance trap catches while high concentrations acted inhibitory.ZusammenfassungOxidierte Terpene im chemischen Kommunikationssystem des Borkenkäfers Ips schmutzenhoferi (Col., Scolytidae) aus BhutanDas Aggregationsverhalten der kürzlich für den südöstlichen Himalaya neu beschriebenen Borkenkäferart Ips schmutzenhoferi wurde im Labor und Freiland untersucht. Männchen, die in der Rinde eines Wirtsbaumes fressen, lösen die Aggregation aus und produzieren große Mengen des Terpenalkohols Ipsenol; außerdem sind noch geringere Mengen an cis‐Verbenol und Ipsdienol sowie Spuren von Ipsenon nachweisbar. Im Labor und Freiland ist racemisches Ipsenol lockwirksam, und seine Lockwirkung wird im Freiland durch (S)‐cis‐Verbenol synergistisch verstärkt. Geringe Mengen racemischen Ipsdienols scheinen den Anflug von I. schmutzenhoferi an Lockstoffallen zu erhöhen, während größere Mengen die Fangzahlen reduzieren.

Schweizerische Zeitschrift Fur Forstwesen, Mar 1, 2012

Hermann spellmann Nordwestdeutsche Forstliche Versuchsanstalt (DE) Andreas weller Nordwestdeutsch... more Hermann spellmann Nordwestdeutsche Forstliche Versuchsanstalt (DE) Andreas weller Nordwestdeutsche Forstliche Versuchsanstalt (DE) Growth and value production of Douglas-fir under varying stand densities The investigation is focused on the effects of initial tree number and thinning on growth and value perfor mance of Douglas-fir stands. Data base is a coordinated Douglas-fir spacing experiment in South Germany, started 40 years ago and comprising variants of tree numbers with 500, 1,000, 2,000 and 4,000 Douglas-firs per hectare. The treatment was performed according to a standardized experiment program. The results show that at low initial tree numbers, the diameter on breast height (DBH) of (pre)dominant trees at the beginning of the observations (with 12 m top height) is bigger than at higher initial plant numbers. Accordingly, the quotient of height (H) to DBH (as an indicator for tree's static stability) is lower. The further development of DBH and H/DBH quotient is decisively determined by stand treatment, which superimposes the effect of the initial tree number. The total volume growth shows a clear differentiation, too, the variants with initially high tree numbers appearing on top. In the monetary analysis, this ranking is reversed: despite a supposed inferior wood quality, the variants with lower initial tree numbers clearly outperform the ones with higher numbers in terms of value. From these results, the following silvicultural recommendations for Douglas-fir can be derived: the initial tree numbers should be in the range from 1,000 to 2,000 plants per hectare. On technically not accessible sites, even lower tree numbers may come into question. The strong influence of stand treatment on DBH and H/DBH development highlights the problem of postponed thinnings, for this causes growth and stability losses even under favorable starting conditions in terms of competition.

Journal of Applied Entomology, Jan 12, 1994

... BARTELS, J.; MEYER, H.; FRANCKE, W. 1993: Chemical communication in the European pine engrave... more ... BARTELS, J.; MEYER, H.; FRANCKE, W. 1993: Chemical communication in the European pine engraver, Ips manns eldi (Col., Scolytidae). J. Appl. Ent. 115,l-7. I. grandicollis (Eichh.) and the occurrence of both species in Central America. Can. Ent. 119, 179-187. LANIER, G. N ...

Annals of forest science, 2010

Existing growth and yield plots of pure and mixed stands of Norway spruce (Picea abies (L.) H. Ka... more Existing growth and yield plots of pure and mixed stands of Norway spruce (Picea abies (L.) H. Karst.) and European beech (Fagus sylvatica L.) were aggregated in order to unify the somewhat scattered sources of information currently available, as well as to develop a sound working hypothesis about mixing effects. The database contains information from 23 long-term plots, covering an ecological gradient from nutrient poor and dry to nutrient rich and moist sites throughout Central Europe. • An empirically formed interaction model showed, that depending on the site conditions, dry mass growth in mixed stands can range from −46% to +138 % of the growth yielded by a scaled combination of pure stands at equal mixing proportions. • Drawing from the interaction model, overyielding of the mixed stands appears to be triggered by two separate mechanisms. On poor sites, where significant overyielding is commonly found, facilitation by beech offsets nutrient-related growth limitations in spruce. In contrast, overyielding of mixed stands occurs less frequently on rich sites, and appears to be based on an admixture effect, with spruce reducing the severe intra-specific competition common in pure beech stands. • It was concluded that silviculture can accelerate growth of spruce by beech admixtures on poor sites, while growth of beech can be promoted by admixture of spruce, particularly on excellent sites.

Holz-Zentralblatt : unabhängiges Organ für die Forst- und Holzwirtschaft, 2018

Aus der Forschung sçå=rïÉ=pÅÜãáííGI=gçÜ~ååÉë=tÉääáåÖGI=dÉê~äÇ=hçÅÜGI bÅâÜ~êÇ=jÉäÅÜÉêGI=g~åJeÉååáå... more Aus der Forschung sçå=rïÉ=pÅÜãáííGI=gçÜ~ååÉë=tÉääáåÖGI=dÉê~äÇ=hçÅÜGI bÅâÜ~êÇ=jÉäÅÜÉêGI=g~åJeÉååáåÖ=_äçÜãGI=räêáÅÜ=hçÜåäÉGGI cê~åâ~=_êΩÅÜÉêíGG=ìåÇ=rÇç=e~åë=p~ìíÉêGG as natürliche Verbreitungsgebiet der Douglasie (Pseudotsuga menziesii (Mirb.) Franco) liegt im Westen Nordamerikas. Bei dieser Baumart werden zwei populationsgenetisch voneinander abweichende Formen unterschieden, die nach ihren Hauptvorkommensgebieten als Küstenbzw. Inlands-Douglasien bezeichnet werden. Beide wachsen in Waldgesellschaften mit Westlicher Hemlocktanne, Küstentanne, Küstenmammutbaum und Zucker-Kiefer. Für den Anbau in Mitteleuropa hat sich die Küsten-Douglasie bewährt, die aus dem pazifischen Nordwesten stammt und in der westkanadischen Provinz Britisch-Kolumbien sowie den US-Bundesstaaten Oregon, Washington und Kalifornien natürlich beheimatet ist. Die sehr gute Holzqualität der Douglasie bei gleichzeitig leichter Verarbeitbarkeit machten sie in Nordamerika zu

Schweizerische Zeitschrift Fur Forstwesen, Mar 1, 2021

Der erwartete Klimawandel macht die Douglasie (Pseudotsuga menziesii [Mirb.] Franco) zu einer vie... more Der erwartete Klimawandel macht die Douglasie (Pseudotsuga menziesii [Mirb.] Franco) zu einer vielversprechenden Option für die Waldbewirtschaftung in Mitteleuropa. Die Art ist resistenter gegenüber Trockenheit als zum Beispiel die Fichte, wächst sehr gut und liefert wertvolles Sägeholz mit überlegenen technischen Holzeigenschaften. Die über ein Jahrhundert vor allem in Frankreich und in Deutschland gesammelte Erfahrung in Forschung und Praxis hat substanzielles, evidenzbasiertes waldbauliches Wissen zur Bewirtschaftung der Douglasie in Europa geschaffen. Der Artikel hat zum Ziel, die wichtigsten Aspekte darzustellen. Während die mit relativ hohen Kosten verbundene Pflanzung bislang die gebräuchlichste Begründungstechnik in Europa war, wird das offensichtliche Potenzial der natürlichen Verjüngung mit grosser Wahrscheinlichkeit an Bedeutung gewinnen. Allerdings wird die Wurzelentwicklung junger Bäume sowohl durch Überschirmung als auch durch seitliche Konkurrenz negativ beeinflusst. Wenn die Douglasie unter Schirm verjüngt werden soll, muss die Dauer der Überschirmung kurz gehalten und die seitlichen Konkurrenten frühzeitig und entschlossen entfernt werden. Das Durchmesserwachstum lässt sich durch geeignete Pflanzabstände, Durchforstung und die Wahl der Produktionszeiträume gezielt steuern. Die Holzqualität kann durch die Auswahl von Z-Bäumen und eine Ästung verbessert werden. Um den Anteil an qualitativ minderwertigen schwachen Sortimenten klein zu halten, kann ein längerer Produktionszeitraum in Verbindung mit grösserem Zieldurchmesser als Bewirtschaftungsoption in Betracht gezogen werden. Allerdings sind längere Produktionszeiträume ausnahmslos mit höheren Risiken verbunden, insbesondere nimmt das Sturmschadenrisiko mit der Baumhöhe progressiv zu. Im Zusammenhang mit dem Risikomanagement und der Integration der nicht einheimischen Douglasie in naturnahe Bewirtschaftungssysteme sind die Begründung und die Bewirtschaftung von Mischbeständen von grosser Bedeutung.

Zeitschrift für Naturforschung C, Dec 1, 1988

Ipsenol, Ipsdienol, and £-myrcenol are male specific compounds of Ips schmutzenhoferi. Overall 46... more Ipsenol, Ipsdienol, and £-myrcenol are male specific compounds of Ips schmutzenhoferi. Overall 46 compounds could be identified from males and females. The diversity of oxygenated terpenes is particularly high in males.

Agricultural and Forest Meteorology, May 1, 2017

The annual growth of the Finnish forests has doubled in less than a century but the reasons for t... more The annual growth of the Finnish forests has doubled in less than a century but the reasons for the increase have been a subject of much debate. Site index aggregates the mid-to long-term impacts of variable edaphic and climatic factors on site productivity and is an important characteristic with regard to the ongoing environmental changes. We quantified changes of site index in Finland over time by applying a new approach developed in our previous study in Germany. A large data base for Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and larch (Larix spp.) was available from the network of long-term growth and yield experiments in southern and central Finland. For all tree species, site indices fluctuated over time, i.e. they slightly decreased in the 1970s, followed by an increasing trend in the 1980s and a decline again in the 1990s. Apparently, the only significant change was a change point indicated for Scots pine around the year 1944; however, indication was weak due to notable limitations of the database during the respective period. Interestingly, the result of this study in Finland differs from central Europe, where Norway spruce site productivity has displayed a considerable increase since the 1950s. Potentially, the low nitrogen deposition in Finland may be of major importance accounting for the divergent changes in site productivity between Finland and central Europe. Thus, the results indicate that a large share of the growth increase in the Finnish forests might actually be due to altered management.

Zeitschrift für Angewandte Entomologie, Aug 26, 2009

ABSTRACT Antennal olfactory and behavioral responses by sympatric ambrosia beetles, Trypodendron ... more ABSTRACT Antennal olfactory and behavioral responses by sympatric ambrosia beetles, Trypodendron lineatum, T. domesticum and T. signatum, to their aggregation pheromone lineatin was found to be specific to the (+)-enantiomer. The (-)-antipode was inactive thus showing no indication of synergistic or repellent effects. The results indicate that these closely related congenerics use an identical pheromonal signal and suggest that reproductive isolation is achieved by other mechanisms. Die Reaktion sympatrischer Trypodendron-Arten auf optisch aktives Lineatin: Elektroantennogramm und Freilandtest Die Nutzholzborkenkäfer Trypodendron lineatum, T. domesticum und T. signatum reagierten im Elektroantennogramm und an Lockstoff-Fallen nur auf die (+)-Enantiomere ihres Aggregations-pheromons Lineatin. Der (-)-Antipode zeigte weder fördernde noch hemmende Wirkung. Alle drei sympatrischen Trypodendron-Anen verwenden somit das gleiche Aggregationspheromon; die Artentrennung wird offenbar durch andere Mechanismen erreicht.

Naturwissenschaften, 1984

Zeitschrift für Angewandte Entomologie, Aug 26, 2009

Investigations on the aggregation pheromone of the mediterranean engraver beetle Ips (Orthotomicu... more Investigations on the aggregation pheromone of the mediterranean engraver beetle Ips (Orthotomicus) erosus Attempts were made to identify the aggregation pheromone produced by male I. erosus while initiating attack on Pinus inaster by gas chromatographic analyses of headspace gas obtained from the hindguts of male bee&. The chemical analysis and field tests in South African pine plantations indicate 2-methyl-6-merhylene-2,7-octadien-4-01 (ipsdienol) and 2-methyl-3-buten-2-01 to represent the major components of an aggregating principle that could be utilized in the surveillance of this world wide expanding insect pest.

Allgemeine Forst Und Jagdzeitung, 2014

Allgemeine Forst Und Jagdzeitung, 2009

Forest Ecology and Management, Jul 1, 2021

The maximum size-density relationship describes site carrying capacity, i.e., the maximum number ... more The maximum size-density relationship describes site carrying capacity, i.e., the maximum number of trees of a given size that can be stocked per unit area (self-thinning line). We analysed whether the self-thinning lines of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) have remained unchanged over time in South Germany, Norway and Finland, i.e., over a wide climatic gradient from Central Europe up to the Arctic circle. The analyses are based on long-term growth and yield experiments measured on individual tree basis over several decades, the oldest experiments established during the early 20th century. The stochastic frontier analysis was used to analyse changes in the species-specific self-thinning lines. The results show that the self-thinning lines have shifted upwards over time in all the regions. Thus, currently stands sustain higher stand densities than in the past. The increase of the maximum density for a given average stem size was more pronounced for pine than for spruce, but similar in all studied geographical regions. In addition, increasing site index was associated with increasing site carrying capacity for spruce and pine in all regions. The results imply that environmental changes have altered site properties in similar fashion across the whole study region. In practical forestry, increased site carrying capacity will reduce mortality and loss of growing stock.

Naturwissenschaften, Mar 1, 1991

Journal of Applied Entomology, Jan 12, 1993

Host selecting males of Ips mannsfeldi release (S)‐(+)‐ipsdienol, (S)‐(‐)‐ipsenol, amitinol and 2... more Host selecting males of Ips mannsfeldi release (S)‐(+)‐ipsdienol, (S)‐(‐)‐ipsenol, amitinol and 2‐methyl‐6‐methylene‐1,3E,7‐octatriene (“ipstriene”) as major beetle specific volatiles and obviously employ the terpene alcohols in a frass pheromone system. A vertex‐pronotal stridulatory organ is present in the females.ZusammenfassungDas Pheromonsystem des Schwarzkiefern‐Borkenkäfers Ips mannsfeldi (Wachtl) (Col., Scolytidae)Wirtswählende Ips mannsfeldi Männchen geben größere Mengen an (S)‐(+)‐Ipsdienol, (S)‐(‐)‐Ipsenol, Amitinol und 2‐Methyl‐6‐methylen‐1,3E,7‐octatrien (“Ipstrien”) als käferspezifische Duftstoffe beim Befall eines Wirtsbaumes ab. Die Terpenalkohole Ipsdienol und Ipsenol bilden als Synergisten ein Fraßpheromonsystem, das die Aggregation der Käfer an temporären Habitaten in geschwächten Wirtsbäumen auslöst. Elektronenmikroskopische Untersuchungen zeigen bei den Weibchen ein Stridulationsorgan vom Vertex‐Pronotal‐Typ, das bei den Männchen fehlt.

Zeitschrift für Angewandte Entomologie, Aug 26, 2009

Investigations of chemical communication systems in secondary bark beetles (Col., Scolytidae) The... more Investigations of chemical communication systems in secondary bark beetles (Col., Scolytidae) The chemical communication system of several secondary European bark beetles was investigated. The ash bark beetle, Leperisinus varius, responded in the field to ethanol‐baited traps in significant numbers. Male‐released exo‐brevicomin increased trap catches of L. varius while another male specific compound, 7‐methyl‐1,6‐dioxaspiro [4.5] decane, proved inhibitory. Hylurgops palliatus, a species colonizing Norway spruce was attracted to traps containing ethanol as a bait; spruce resin acted synergistically. For Dryocoetes autographus, another spruce bark beetle, females were shown to be the host selecting sex, suggesting this species to be monogynous. However, the males release endo‐ and exo‐brevicomin which attracted predominantely female D. autographus in the field. With endo‐brevicomin, only the (+)‐enantiomer elicited response of D. autographus while the antipode did not affect beetle response.In polygynous bark beetle species males are the host selecting sex and as a rule release the aggregating pheromone(s) which attract both males and females. Dispersal losses of hostsearching males are compensated through male polygyny. In contrast, some monogynous bark beetles such as D. autographus seem to balance the sex ratio during host colonization through sexual crossattractiveness of sex‐specific pheromones: Male and female beetles release different pheromone components attracting predominantely beetles of the opposite sex; a phenomenom characteristic for sex pheromones of Lepidoptera.Within associations of bark beetles colonizing Norway spruce investigated in this study, kairomonal effects of pheromones were common. E.g., the aggressive species Ips typographus and Pityogenes chalcographus were attracted to some extent to endo‐ or exo‐brevicomin, pheromone components of secondary D. autographus. In contrast, response of D. autographus to baited traps was inhibited when pheromone components of the aggressive species were added.ZusammenfassungDas Aggregationsverhalten verschiedener sekundärer Borkenkäfer wurde untersucht.Hylurgops palliatus: Duftstoffe des Wirts und Ethanol locken synergistisch.Leperisinus varius: Im Freiland locken Ethanol und das ♂‐spezifische exo‐Brevicomin; ein weiterer Duftstoff der ♂♂, 7‐Methyl‐1,6‐dioxaspiro [4.5] decan, ist ein Ablenkstoff.Dryocoetes autographus: Das (+)‐Isomer des ♂‐spezifischen endo‐Brevicomin lockt im Freiland zahlreiche Käfer, während der Antipode biologisch inaktiv ist. Die ♂♂ locken mit endo‐bzw. exo‐Brevicomin vorwiegend die ♀♀ an; die Lockwirksamkeit dieser Pheromone wird durch Ethanol und Terpene verstärkt.Die Anlockung der D. autographus‐♀♀ durch ♂‐spezifische Pheromone weist auf ein Aggregationsprinzip hin, das in dieser Arbeit diskutiert wird: das Prinzip der geschlechtsorientierten Anlockung; ♀♀ und/oder ♂♂ locken sich gegenseitig mit Pheromonen, die in Abgabe und Wirkung geschlechtsspezifisch sein können. Hierdurch gelingt es monogynen Arten, den Wirt in einem ausgewogenen Geschlechterverhältnis zu besiedeln, während andere Arten das Geschlechterverhältnis der angelockten Käfer durch die Polygynie der ♂ ausgleichen.Zwischen assoziierten Fichtenborkenkäfern treten zahlreiche kairomonale Effekte von Pheromonkomponenten auf. So werden beispielsweise die aggressiven Rindenbrüter Ips typographus bzw. Pityogenes chalcographus von endo‐ bzw. exo‐Brevicomin des sekundären D. autographus angelockt, während umgekehrt Pheromonkomponenten der beiden aggressiven Arten auf D. autographus ablenkend wirken.

Naturwissenschaften, May 1, 1986

Journal of Applied Entomology, Jan 12, 1986

... Acal Sci. Hungar. 9, 237-270. JEPPSON, LR; KEIFER, HH and BAKER, EW, 1975: Mites injurious to... more ... Acal Sci. Hungar. 9, 237-270. JEPPSON, LR; KEIFER, HH and BAKER, EW, 1975: Mites injurious to economic plants. Univ. of California Press, Berkeley, CA, 613 pp. ... Ph. D. Thesis. Univ. of Sofia, Bulgaria. ROIVAINEN, H., 1950: Erio hyid news from Sweden. Acta Entomol. Fenn. ...

Journal of Applied Entomology, Jan 12, 1988

Upon feeding in the bark of a host tree, Ips schmutzenhoferi males release major amounts of ipsen... more Upon feeding in the bark of a host tree, Ips schmutzenhoferi males release major amounts of ipsenol along with traces of ipsenone and ipsdienol. Racemic ipsenol proved attractive in laboratory and field bioassays. Field response of I. schmutzenhoferi was synergized by adding (S)‐cis‐verbenol to the bait material. Low concentrations of racemic ipsdienol seemed to enhance trap catches while high concentrations acted inhibitory.ZusammenfassungOxidierte Terpene im chemischen Kommunikationssystem des Borkenkäfers Ips schmutzenhoferi (Col., Scolytidae) aus BhutanDas Aggregationsverhalten der kürzlich für den südöstlichen Himalaya neu beschriebenen Borkenkäferart Ips schmutzenhoferi wurde im Labor und Freiland untersucht. Männchen, die in der Rinde eines Wirtsbaumes fressen, lösen die Aggregation aus und produzieren große Mengen des Terpenalkohols Ipsenol; außerdem sind noch geringere Mengen an cis‐Verbenol und Ipsdienol sowie Spuren von Ipsenon nachweisbar. Im Labor und Freiland ist racemisches Ipsenol lockwirksam, und seine Lockwirkung wird im Freiland durch (S)‐cis‐Verbenol synergistisch verstärkt. Geringe Mengen racemischen Ipsdienols scheinen den Anflug von I. schmutzenhoferi an Lockstoffallen zu erhöhen, während größere Mengen die Fangzahlen reduzieren.

Schweizerische Zeitschrift Fur Forstwesen, Mar 1, 2012

Hermann spellmann Nordwestdeutsche Forstliche Versuchsanstalt (DE) Andreas weller Nordwestdeutsch... more Hermann spellmann Nordwestdeutsche Forstliche Versuchsanstalt (DE) Andreas weller Nordwestdeutsche Forstliche Versuchsanstalt (DE) Growth and value production of Douglas-fir under varying stand densities The investigation is focused on the effects of initial tree number and thinning on growth and value perfor mance of Douglas-fir stands. Data base is a coordinated Douglas-fir spacing experiment in South Germany, started 40 years ago and comprising variants of tree numbers with 500, 1,000, 2,000 and 4,000 Douglas-firs per hectare. The treatment was performed according to a standardized experiment program. The results show that at low initial tree numbers, the diameter on breast height (DBH) of (pre)dominant trees at the beginning of the observations (with 12 m top height) is bigger than at higher initial plant numbers. Accordingly, the quotient of height (H) to DBH (as an indicator for tree's static stability) is lower. The further development of DBH and H/DBH quotient is decisively determined by stand treatment, which superimposes the effect of the initial tree number. The total volume growth shows a clear differentiation, too, the variants with initially high tree numbers appearing on top. In the monetary analysis, this ranking is reversed: despite a supposed inferior wood quality, the variants with lower initial tree numbers clearly outperform the ones with higher numbers in terms of value. From these results, the following silvicultural recommendations for Douglas-fir can be derived: the initial tree numbers should be in the range from 1,000 to 2,000 plants per hectare. On technically not accessible sites, even lower tree numbers may come into question. The strong influence of stand treatment on DBH and H/DBH development highlights the problem of postponed thinnings, for this causes growth and stability losses even under favorable starting conditions in terms of competition.

Journal of Applied Entomology, Jan 12, 1994

... BARTELS, J.; MEYER, H.; FRANCKE, W. 1993: Chemical communication in the European pine engrave... more ... BARTELS, J.; MEYER, H.; FRANCKE, W. 1993: Chemical communication in the European pine engraver, Ips manns eldi (Col., Scolytidae). J. Appl. Ent. 115,l-7. I. grandicollis (Eichh.) and the occurrence of both species in Central America. Can. Ent. 119, 179-187. LANIER, G. N ...