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The sooty bark disease (SBD) is an emerging disease affecting sycamore maple trees (Acer pseudoplatanus) in Europe. Cryptostroma corticale, the causal agent, putatively native to eastern North America, can be also pathogenic for humans causing pneumonitis. It was first detected in 1945 in Europe, with markedly increasing reports since 2000. Pathogen development appears to be linked to heat waves and drought episodes. Here, we analyse the conditions of the SBD emergence in Europe based on a three-decadal time-series data set. We also assess the suitability of aerobiological samples using a species-specific quantitative PCR assay to inform the epidemiology of C. corticale, through a regional study in France comparing two-year aerobiological and epidemiological data, and a continental study including 12 air samplers from six countries (Czechia, France, Italy, Portugal, Sweden and Switzerland). We found that an accumulated water deficit in spring and summer lower than -132 mm correlates with SBD outbreaks. Our results suggest that C. corticale is an efficient airborne pathogen which can disperse its conidia as far as 310 km from the site of the closest disease outbreak. Aerobiology of C. corticale followed the SBD distribution in Europe. Pathogen detection was high in countries within the host native area and with longer disease presence, such as France, Switzerland and Czech Republic, and sporadic in Italy, where the pathogen was reported just once. The pathogen was absent in samples from Portugal and Sweden, where the disease has not been reported yet. We conclude that aerobiological surveillance can inform the spatial distribution of the SBD, and contribute to early detection in pathogen-free countries.

The sooty bark disease (SBD) is an emerging disease affecting sycamore maple trees (Acer pseudoplatanus) in Europe. Cryptostroma corticale, the causal agent, putatively native to eastern North America, can be also pathogenic for humans causing pneumonitis. It was first detected in 1945 in Europe, with markedly increasing reports since 2000. Pathogen development appears to be linked to heat waves and drought episodes. Here, we analyse the conditions of the SBD emergence in Europe based on a three-decadal time-series data set. We also assess the suitability of aerobiological samples using a species-specific quantitative PCR assay to inform the epidemiology of C. corticale, through a regional study in France comparing two-year aerobiological and epidemiological data, and a continental study including 12 air samplers from six countries (Czechia, France, Italy, Portugal, Sweden and Switzerland). We found that an accumulated water deficit in spring and summer lower than -132 mm correlates with SBD outbreaks. Our results suggest that C. corticale is an efficient airborne pathogen which can disperse its conidia as far as 310 km from the site of the closest disease outbreak. Aerobiology of C. corticale followed the SBD distribution in Europe. Pathogen detection was high in countries within the host native area and with longer disease presence, such as France, Switzerland and Czech Republic, and sporadic in Italy, where the pathogen was reported just once. The pathogen was absent in samples from Portugal and Sweden, where the disease has not been reported yet. We conclude that aerobiological surveillance can inform the spatial distribution of the SBD, and contribute to early detection in pathogen-free countries.

The sooty bark disease (SBD) is an emerging disease affecting sycamore maple trees (Acer pseudoplatanus) in Europe. Cryptostroma corticale, the causal agent, putatively native to eastern North America, can be also pathogenic for humans causing pneumonitis. It was first detected in 1945 in Europe, with markedly increasing reports since 2000. Pathogen development appears to be linked to heat waves and drought episodes. Here, we analyse the conditions of the SBD emergence in Europe based on a three-decadal time-series data set. We also assess the suitability of aerobiological samples using a species-specific quantitative PCR assay to inform the epidemiology of C. corticale, through a regional study in France comparing two-year aerobiological and epidemiological data, and a continental study including 12 air samplers from six countries (Czechia, France, Italy, Portugal, Sweden and Switzerland). We found that an accumulated water deficit in spring and summer lower than -132 mm correlates with SBD outbreaks. Our results suggest that C. corticale is an efficient airborne pathogen which can disperse its conidia as far as 310 km from the site of the closest disease outbreak. Aerobiology of C. corticale followed the SBD distribution in Europe. Pathogen detection was high in countries within the host native area and with longer disease presence, such as France, Switzerland and Czech Republic, and sporadic in Italy, where the pathogen was reported just once. The pathogen was absent in samples from Portugal and Sweden, where the disease has not been reported yet. We conclude that aerobiological surveillance can inform the spatial distribution of the SBD, and contribute to early detection in pathogen-free countries., info:eu-repo/semantics/openAccess

Esdoorns scoren punten met hun vroege bladeren en herfstkleuren. En soms met de vorm. Een praktische duik in het enorme sortiment bomen binnen dit geslacht.

In Kijk op Exoten nr. 30 (2020) is uitgebreid aandacht besteed aan de roetschorsschimmel (Cryptostroma corticale). Deze exoot uit Noord-Amerika veroorzaakt een dodelijke ziekte onder esdoorns en brengt ook gezondheidsrisico’s voor de mens met zich mee. Meldingen komen tot nu toe vooral uit stedelijk gebied, waar veel esdoorns zijn aangeplant in parken, tuinen en langs wegen. Maar de ziekte kan ook bosopstanden met esdoorn op grotere schaal aantasten. Om die reden vragen we opnieuw aandacht voor de verbreiding van de roetschorsschimmel

The sooty bark disease (SBD) is an emerging disease affecting sycamore maple trees (Acer pseudoplatanus) in Europe. Cryptostroma corticale, the causal agent, putatively native to eastern North America, can be also pathogenic for humans causing pneumonitis. It was first detected in 1945 in Europe, with markedly increasing reports since 2000. Pathogen development appears to be linked to heat waves and drought episodes. Here, we analyse the conditions of the SBD emergence in Europe based on a three-decadal time-series data set. We also assess the suitability of aerobiological samples using a species-specific quantitative PCR assay to inform the epidemiology of C. corticale, through a regional study in France comparing two-year aerobiological and epidemiological data, and a continental study including 12 air samplers from six countries (Czechia, France, Italy, Portugal, Sweden and Switzerland). We found that an accumulated water deficit in spring and summer lower than -132 mm correlates with SBD outbreaks. Our results suggest that C. corticale is an efficient airborne pathogen which can disperse its conidia as far as 310 km from the site of the closest disease outbreak. Aerobiology of C. corticale followed the SBD distribution in Europe. Pathogen detection was high in countries within the host native area and with longer disease presence, such as France, Switzerland and Czech Republic, and sporadic in Italy, where the pathogen was reported just once. The pathogen was absent in samples from Portugal and Sweden, where the disease has not been reported yet. We conclude that aerobiological surveillance can inform the spatial distribution of the SBD, and contribute to early detection in pathogen-free countries.

The sooty bark disease (SBD) is an emerging disease affecting sycamore maple trees (Acer pseudoplatanus) in Europe. Cryptostroma corticale, the causal agent, putatively native to eastern North America, can be also pathogenic for humans causing pneumonitis. It was first detected in 1945 in Europe, with markedly increasing reports since 2000. Pathogen development appears to be linked to heat waves and drought episodes. Here, we analyse the conditions of the SBD emergence in Europe based on a three-decadal time-series data set. We also assess the suitability of aerobiological samples using a species-specific quantitative PCR assay to inform the epidemiology of C. corticale, through a regional study in France comparing two-year aerobiological and epidemiological data, and a continental study including 12 air samplers from six countries (Czechia, France, Italy, Portugal, Sweden and Switzerland). We found that an accumulated water deficit in spring and summer lower than -132 mm correlates with SBD outbreaks. Our results suggest that C. corticale is an efficient airborne pathogen which can disperse its conidia as far as 310 km from the site of the closest disease outbreak. Aerobiology of C. corticale followed the SBD distribution in Europe. Pathogen detection was high in countries within the host native area and with longer disease presence, such as France, Switzerland and Czech Republic, and sporadic in Italy, where the pathogen was reported just once. The pathogen was absent in samples from Portugal and Sweden, where the disease has not been reported yet. We conclude that aerobiological surveillance can inform the spatial distribution of the SBD, and contribute to early detection in pathogen-free countries., info:eu-repo/semantics/openAccess

The sooty bark disease (SBD) is an emerging disease affecting sycamore maple trees (Acer pseudoplatanus) in Europe. Cryptostroma corticale, the causal agent, putatively native to eastern North America, can be also pathogenic for humans causing pneumonitis. It was first detected in 1945 in Europe, with markedly increasing reports since 2000. Pathogen development appears to be linked to heat waves and drought episodes. Here, we analyse the conditions of the SBD emergence in Europe based on a three-decadal time-series data set. We also assess the suitability of aerobiological samples using a species-specific quantitative PCR assay to inform the epidemiology of C. corticale, through a regional study in France comparing two-year aerobiological and epidemiological data, and a continental study including 12 air samplers from six countries (Czechia, France, Italy, Portugal, Sweden and Switzerland). We found that an accumulated water deficit in spring and summer lower than -132 mm correlates with SBD outbreaks. Our results suggest that C. corticale is an efficient airborne pathogen which can disperse its conidia as far as 310 km from the site of the closest disease outbreak. Aerobiology of C. corticale followed the SBD distribution in Europe. Pathogen detection was high in countries within the host native area and with longer disease presence, such as France, Switzerland and Czech Republic, and sporadic in Italy, where the pathogen was reported just once. The pathogen was absent in samples from Portugal and Sweden, where the disease has not been reported yet. We conclude that aerobiological surveillance can inform the spatial distribution of the SBD, and contribute to early detection in pathogen-free countries., info:eu-repo/semantics/openAccess

Trees have a strong influence on the chemical properties of the soil in which they grow. Establishing plantations with different tree species combinations thus potentially leads to divergence in soil chemistry. To study the degree to which differentiation already occurs during the first years after establishment, we made use of a biodiversity– ecosystem functioning experiment in Belgium, FORBIO. The multi-site experiment replicates tree species richness (1–4 species) and composition in three sites. The sites represent contrasting site contexts, mostly land-use history, soil, and climate. Soil samples (0–10 cm) were taken at the time of planting and approximately 8 years later. We measured the total C and N concentration, the Olsen P, the pHH2O, and the concentration of base and Al cations. The change in chemical composition was strongly dependent on site conditions including former land use. Afforestation on former cropland had a positive impact on totalCand Olsen P and a negative effect on base cations and pH. On sites reforested after clearcut, soil texture and particular site preparation played an important role. On top of that, we found several significant effects of species composition. Strongest composition effects were detected in the reforested site on loamy soil with little soil disturbance. This study highlights that species choice can already affect soil chemistry in early stages of forest development, but that the nature of the effects may strongly depend on the context in which the plantations are established. Further research is needed to identify the most important contextual factors.

Marknaden för sågbara sortiment från svenskt lövvirke har haft svårt att fungera på ett tillfredställande sätt, tydligast är problematiken kring de mer udda trädslagen. Råvaran finns i de svenska skogarna och avsättning för råvaran finns i industrin men flödet från skog till industri har tydliga brister. Lösningen har blivit att industrin importerar stor andel av sin lövråvara vilket missgynnar avsättningen av den inhemska råvaran.Studiens främsta syfte var att undersöka avsättningsmöjligheterna för svensk sykomorlönn och lind kopplat till en nulägesbeskrivning av ett tidigare anlagt lövträdsförsök. Resultatet visade att avsättningsmöjligheterna varierade över tid men vid studien var efterfrågan på sykomorlönn svag medan den på lind var stark. Tidpunkten för slutavverkning av de aktuella trädslagen bör således väljas efter när prisbilden är hög.Studien visade att skötseln av de undersökta trädslagen är mycket viktig för att optimera kvaliteten och avsättningsmöjligheterna. De viktigaste parametrarna för god kvalitet var kvist och stamdimension. En större leveransbar volym vid den enskilda avverkningen ökade också avsättningsmöjligheterna. Nyckelord: Acer pseudoplatanus, Tilia cordata, Marknad, Avsättning, Skogsskötsel Keywords: Acer pseudoplatanus, Tilia cordata, Market, Removal, Forest management

Marknaden för sågbara sortiment från svenskt lövvirke har haft svårt att fungera på ett tillfredställande sätt, tydligast är problematiken kring de mer udda trädslagen. Råvaran finns i de svenska skogarna och avsättning för råvaran finns i industrin men flödet från skog till industri har tydliga brister. Lösningen har blivit att industrin importerar stor andel av sin lövråvara vilket missgynnar avsättningen av den inhemska råvaran.Studiens främsta syfte var att undersöka avsättningsmöjligheterna för svensk sykomorlönn och lind kopplat till en nulägesbeskrivning av ett tidigare anlagt lövträdsförsök. Resultatet visade att avsättningsmöjligheterna varierade över tid men vid studien var efterfrågan på sykomorlönn svag medan den på lind var stark. Tidpunkten för slutavverkning av de aktuella trädslagen bör således väljas efter när prisbilden är hög.Studien visade att skötseln av de undersökta trädslagen är mycket viktig för att optimera kvaliteten och avsättningsmöjligheterna. De viktigaste parametrarna för god kvalitet var kvist och stamdimension. En större leveransbar volym vid den enskilda avverkningen ökade också avsättningsmöjligheterna. Nyckelord: Acer pseudoplatanus, Tilia cordata, Marknad, Avsättning, Skogsskötsel Keywords: Acer pseudoplatanus, Tilia cordata, Market, Removal, Forest management

Purpose - The paper presents a theoretical framework that describes the aerodynamics of a falling maple (Acer pseudoplatanus) seed. --- Methodology - A semi-empirical method is developed that provides a ratio stating how much longer a seed falls in air compared to freefall. The generated lift is calculated by evaluating the integral of two-dimensional airfoil elements using a preliminary falling speed. This allows for the calculation of the definitive falling speed using Blade Element Momentum Theory (BEMT); hereafter, the fall duration in air and in freefall are obtained. Furthermore, the input-variables of the calculation of lift are transformed to require only the length and width of the maple seed. Lastly, the method is applied to two calculation examples as a means of validation. --- Findings - The two example calculations gave percentual errors of 5.5% and 3.7% for the falling speed when compared to measured values. The averaged result is that a maple seed falls 9.9 times longer in air when released from 20 m; however, this result is highly dependent on geometrical parameters which can be accounted for using the constructed method. --- Research limitations - Firstly, the coefficient of lift is unknown for the shape of a maple seed. Secondly, the approximated transient state is yet to be verified by measurement. --- Originality / Value - The added value of this report lies in the reduction of simplifications compared to BEMT approaches. In this way a large amount of accuracy is achieved due to the inclusion of many geometrical parameters, even though simplicity is maintained. This has been accomplished through constructing a simple three-step method that is fundamental and essentially non-iterative.

Military activities have worldwide introduced toxic explosives into the environment with considerable effects on soil and plant-associated microbiota. Fortunately, these microorganisms, and their collective metabolic activities, can be harnessed for site restoration via in situ phytoremediation. We characterized the bacterial communities inhabiting the bulk soil and rhizosphere of sycamore maple (Acer pseudoplatanus) in two chronically 2,4,6-trinitrotoluene (TNT) polluted soils. Three hundred strains were isolated, purified and characterized, a majority of which showed multiple plant growth promoting (PGP) traits. Several isolates showed high nitroreductase enzyme activity and concurrent TNT-transformation. A 12-member bacterial consortium, comprising selected TNT-detoxifying and rhizobacterial strains, significantly enhanced TNT removal from soil compared to non-inoculated plants, increased root and shoot weight, and the plants were less stressed than the un-inoculated plants as estimated by the responses of antioxidative enzymes. The sycamore maple tree (SYCAM) culture collection is a significant resource of plant-associated strains with multiple PGP and catalytic properties, available for further genetic and phenotypic discovery and use in field applications.

The current database is part of the FEM growth and yield database, a collection of growth and yield data from even-aged monocultures (douglas fir, common oak, poplar, Japanese Larch, Norway spruce, Scots pine, Corsican pine, Austrian pine, red oak and several other species with only a few plots like grand fir, even-aged mixed species forest plots, uneven-aged natural forest, uneven-aged selection forest and roadside plantations of poplar). The FEM growth and yield data base is currently supervised by Jan den Ouden and Frits Mohren.

The current database is part of the FEM growth and yield database, a collection of growth and yield data from even-aged monocultures (douglas fir, common oak, poplar, Japanese Larch, Norway spruce, Scots pine, Corsican pine, Austrian pine, red oak and several other species, with only a few plots, even-aged mixed species forest plots, uneven-aged natural forest, uneven-aged selection forest and roadside plantattions of poplar. The FEM growth and yield data base is currently supervised by Jan den Ouden and Frits Mohren.

Efter askskotts- och almsjukans snabba framfart står det klart att svampsjukdomar inom loppet av ett decennium kan få mångfalden i svenska skogar att se fundamentalt annorlunda ut. Skogsbruket och naturvården saknar två av tidigare alternativ för föryngring av ädellövskog. Sykomorlönn (Acer pseudoplatanus) definieras som invasiv art på grund av dess konkurrenskraft och förmåga att självså sig i etablerade bestånd, men anses intressant av skogsbruket på grund av sin goda tillväxt. Det finns såväl ekologiska som ekonomiska skäl till att närmare förstå den inverkan på biologisk mångfald som det här eventuella skiftet av trädslag inom våra lövskogsekosystem har. Vedlevande svampar utgör en stor ekologiskt och taxonomiskt heterogen grupp som är del av den mångfald som finns knuten till träd. Somliga orsakar sjukdom, medan andra är direkt förbundna med träds välmående och konkurrenskraft. De är på så vis involverade i många ekologiska processer och del av de egenskaper som formar andra organismers relationer till en trädart. Svampar som lever symbiotiskt inuti växtvävnad utan att orsaka symptom kallas endofyter. Den här studien har jämfört diversiteten av endofytiska svampar hos ask (Fraxinus excelsior) och sykomorlönn (A. pseudoplatanus) inom samma bestånd. Bark från individer av respektive trädart samlades in, ytsteriliserades och kultiverades för endofyttillväxt. Sammanlagt 146 isolat sorterades in i 30 morfologiska grupper (morfotyper). Resultaten antyder att koloniseringsgrad, antal morfotyper och fördelning mellan dem är likartad hos de båda trädarterna. Vilka endofyter som finns hos respektive värd skiljer sig dock tydligt åt. Ask och sykomorlönn utgör således lika goda habitat åt endofytiska svampar, men åt olika endofytsamhällen. Resultaten går i linje med liknande studier, men mer data och DNA-sekvensering behövs för att bekräfta dem., In just a decade the tree pathogens causing Dutch elm disease and ash dieback have had great impact on the community of Swedish forests. Hence both nature conservationists and foresters are lacking two species for rejuvenation of broad-leaved forest stands. The sycomore maple (Acer pseudoplatanus) is considered an invasive species because of its competitiveness and ability to spread in mature tree stands. Yet, foresters are interested in the potential of its strong growth. There are both ecological and economic reasons for a better understanding of the impact on biodiversity of this eventual shift of tree species in the broad-leaved ecosystems. Wood-inhabiting fungi represent a large ecologically and taxonomically diverse group which is part of the diversity linked to trees. Some cause disease, while others are directly associated with the fitness and well-being of trees. They are thus involved in many ecological processes, and part of the characteristics that shape other organisms’ relationships to a tree species. Fungi that live symbiotically within plant tissue without causing symptoms are known as endophytes. This study has compared the diversity of endophytic fungi of ash (Fraxinus excelsior) and sycomore maple (A.pseudoplatanus) in the same stand. Bark from individuals of each tree species were collected, surface sterilized and cultivated for endophytic growth. A total of 146 isolates were sorted into 30 morphological groups (morphotypes). The results suggest that the colonization rate, amount and distribution of morphotypes is similar within the two tree species. Which endophytes are associated with each host is however distinct. Ash and sycamore maple are therefore similarly good habitats for fungal endophytes, but support different endophytic communities. The results are in line with similar studies, but more data and DNA sequencing are needed to confirm them.

Climate change is acting on several aspects of plant life cycles, including the sexual reproductive stage, which is considered amongst the most sensitive life-cycle phases. In temperate forests, it is expected that climate change will lead to a compositional change in community structure due to changes in the dominance of currently more abundant forest tree species. Increasing our understanding of the effects of climate change on currently secondary tree species recruitment is therefore important to better understand and forecast population and community dynamics in forests. Here, we analyse the interactive effects of rising temperatures and soil moisture reduction on germination, seedling survival and early growth of two important secondary European tree species, Acer pseudoplatanus and A.platanoides. Additionally, we analyse the effect of the temperature experienced by the mother tree during seed production by collecting seeds of both species along a 2200-km long latitudinal gradient. For most of the responses, A.platanoides showed higher sensitivity to the treatments applied, and especially to its joint manipulation, which for some variables resulted in additive effects while for others only partial compensation. In both species, germination and survival decreased with rising temperatures and/or soil moisture reduction while early growth decreased with declining soil moisture content. We conclude that although A.platanoides germination and survival were more affected after the applied treatments, its initial higher germination and larger seedlings might allow this species to be relatively more successful than A.pseudoplatanus in the face of climate change., AuthorCount:16

Climate change will likely affect population dynamics of numerous plant species by modifying several aspects of the life cycle. Because plant regeneration from seeds may be particularly vulnerable, here we assess the possible effects of climate change on seed characteristics and present an integrated analysis of seven seed traits (nutrient concentrations, samara mass, seed mass, wing length, seed viability, germination percentage, and seedling biomass) of Acer platanoides and A. pseudoplatanus seeds collected along a wide latitudinal gradient from Italy to Norway. Seed traits were analyzed in relation to the environmental conditions experienced by the mother trees along the latitudinal gradient. We found that seed traits of A. platanoides were more influenced by the climatic conditions than those of A. pseudoplatanus. Additionally, seed viability, germination percentage, and seedling biomass of A. platanoides were strongly related to the seed mass and nutrient concentration. While A. platanoides seeds were more influenced by the environmental conditions (generally negatively affected by rising temperatures), compared to A. pseudoplatanus, A. platanoides still showed higher germination percentage and seedling biomass than A. pseudoplatanus. Thus, further research on subsequent life-history stages of both species is needed. The variation in seed quality observed along the climatic gradient highlights the importance of studying the possible impact of climate change on seed production and species demography., AuthorCount:16

This paper discusses determinants of the historical and current spatial extent of the floodplain forest in Leipzig as well as its tree species composition using a GIS-data based delineation model and historical forest inventories for the floodplain forest in the district of Leipzig in Germany from the 19th to the 20th century. We found that the spatial extent of the floodplain forest remained considerably stable in spite of an overall decline in the entire floodplain area from the period where the city first experienced industrialisation in the 19th century to now. However, with river regulations and the alteration of forest management from coppice-with-standards forest to high forest in the 19th century, major changes can be found in the tree species composition of the floodplain forest. Comparing these findings with references from other European floodplain forests we discuss the impact of historical and current forest management as well as the city location''s influence on the extent and tree species composition of urban floodplain forests. For urban forest management in particular there is a great need to integrate biophysical, historical and forestry knowledge when predicting future developmental trends.

This paper discusses determinants of the historical and current spatial extent of the floodplain forest in Leipzig as well as its tree species composition using a GIS-data based delineation model and historical forest inventories for the floodplain forest in the district of Leipzig in Germany from the 19th to the 20th century. We found that the spatial extent of the floodplain forest remained considerably stable in spite of an overall decline in the entire floodplain area from the period where the city first experienced industrialisation in the 19th century to now. However, with river regulations and the alteration of forest management from coppice-with-standards forest to high forest in the 19th century, major changes can be found in the tree species composition of the floodplain forest. Comparing these findings with references from other European floodplain forests we discuss the impact of historical and current forest management as well as the city location''s influence on the extent and tree species composition of urban floodplain forests. For urban forest management in particular there is a great need to integrate biophysical, historical and forestry knowledge when predicting future developmental trends.

Voor groente- en bloemzaden is ruim 10 jaar geleden een schoningstechniek ontwikkeld (vloeistofscheiding), waarbij zaden gesorteerd worden op basis van hun dichtheid. Bij deze techniek worden de zaden kort in vloeistoffen met verschillende dichtheden gebracht en dit resulteert in zaadfracties met verschillende dichtheden. De dichtheid van het zaad correleert met het kiemgedrag. De afgelopen jaren is onderzocht of deze techniek ook perspectief biedt voor boomzaden. Gekozen is voor soorten die met de huidige sorteertechnieken onvoldoende te verbeteren zijn, t.w. Acer pseudoplatanus, Carpinus betulus, Crataegus monogyna, Prunus avium en Larix kaempferi. In twee opeenvolgende jaren zijn 2-3 herkomsten van elke soort gesorteerd door middel van vloeistofscheiden. Dit resulteerde in zaadfracties met verschillende dichtheden. Vaak was de kieming van een fractie beter naarmate de dichtheid van het zaad hoger was. Zaadfracties met de laagste dichtheid kiemden soms helemaal niet of zeer beperkt. Op basis van de kiemcijfers van de verschillende fracties kan dan besloten worden welke fracties uitgezaaid worden. Eventueel kunnen slechter kiemende fracties ook uitgezaaid worden, maar dan dichter of eventueel voor een andere toepassing.

Bosbeheerders hebben regelmatig vragen over de beheersing van soms ongewenste boomsoorten, zoals de uitheemse Amerikaanse vogelkers, de Amerikaanse eik, maar ook de inheemse esdoorn. Deze soorten vormen de uitlopers na afzetten en zijn daarom lastig te verwijderen. Hoe kan dit succesvol worden aangepakt? Hoofdlijnen uit Alterra rapport 843

Bosbeheerders hebben regelmatig vragen over de beheersing van soms ongewenste boomsoorten, zoals de uitheemse Amerikaanse vogelkers, de Amerikaanse eik, maar ook de inheemse esdoorn. Deze soorten vormen de uitlopers na afzetten en zijn daarom lastig te verwijderen. Hoe kan dit succesvol worden aangepakt? Hoofdlijnen uit Alterra rapport 843

Dit rapport geeft een overzicht van effectieve beheermaatregelen voor de beheersing van Amerikaanse vogelkers, esdoorn en Amerikaanse eik, indien noodzakelijk voor de beoogde functievervulling. Voor het bepalen van de beheersingsstrategie is een stappenschema opgesteld en is een ordening gemaakt in de methoden op basis van effectiviteit, kosten, esthetische aspecten, ecologische aspecten en milieu-aspecten. Hiermee kan een bosbeheerder op basis van de huidige kennis van zaken zijn strategie bepalen en een eigen werkplan voorbereiden.

Samenvattingen van 5 presentaties met auteurs en titels: 1) J.F. Salles; P. Garbeva, J.A. van Veen en J.D. van Elsas. Invloed van verschillende gewassen op de diversiteit van Burkholderia-stammen en de selectie van antagonistische isolaten; 2) J.C. Goud, W.J. Blok, A.H.C. Lamers en A.J. Termorshuizen. Lange-termijneffect van biologische grondontsmetting op Verticillium-verwelking bij esdoorn en trompetboom; 3) F.X. Prenafeta-Boldù, R.C. Summerbell en W. Gams. Schimmeldiversiteit in bodems van uiteenlopende rijpheid: vergelijking van isolatieresultaten en moleculaire karakterisering; 4) L.B. Folman. Fungal Bacterial Interactions (FBI), een inventarisatie van microbiële gemeenschappen in bodems met verschillende schimmeldichtheid; 5) M. Viebahn, Christiaan Veenman, Diana Tellekamp, E. Smit, K. Wernars, L.C. van Loon en P.A.H.M. Bakker. Effecten van genetisch gemodificeerde Pseudomonas putida WCS358r op bacteriën en ascomyceten in de rhizosfeer van tarwe

Op veel plaatsen in West-Nederland verdringt de esdoorn andere boomsoorten. Dit kan leiden tot afname van de biodiversiteit zoals het verdwijnen van kruiden, bepaalde soorten paddenstoelen en gallen. Het is belangrijk om dit probleem aan de orde te stellen bij terreinbeheerders en natuurbeschermers.

Samenvattingen van 5 presentaties met auteurs en titels: 1) J.F. Salles; P. Garbeva, J.A. van Veen en J.D. van Elsas. Invloed van verschillende gewassen op de diversiteit van Burkholderia-stammen en de selectie van antagonistische isolaten; 2) J.C. Goud, W.J. Blok, A.H.C. Lamers en A.J. Termorshuizen. Lange-termijneffect van biologische grondontsmetting op Verticillium-verwelking bij esdoorn en trompetboom; 3) F.X. Prenafeta-Boldù, R.C. Summerbell en W. Gams. Schimmeldiversiteit in bodems van uiteenlopende rijpheid: vergelijking van isolatieresultaten en moleculaire karakterisering; 4) L.B. Folman. Fungal Bacterial Interactions (FBI), een inventarisatie van microbiële gemeenschappen in bodems met verschillende schimmeldichtheid; 5) M. Viebahn, Christiaan Veenman, Diana Tellekamp, E. Smit, K. Wernars, L.C. van Loon en P.A.H.M. Bakker. Effecten van genetisch gemodificeerde Pseudomonas putida WCS358r op bacteriën en ascomyceten in de rhizosfeer van tarwe

Beschrijving van het bosbeheer in de stad Den Haag, met speciale aandacht voor de beheersbaarheid van esdoorns in de stadsbossen. Via geïntegreerd bosbeheer streeft de gemeente naar gemengd en structuurrijk bos; het aandeel esdoorn in het kronendak mag niet meer worden dan circa 20 procent. De esdoorn wordt gezien als een ingeburgerde soort, maar zijn uitbundige verjonging en groei vormt een probleem op duinzand in combinatie met eiken of dennen. Kaalkap van esdoorn is de meest effectieve beheersmaatregel maar roept veel weerstand op bij bezoekers. In de praktijk wordt esdoorn geleidelijk teruggedrongen d.m.v. dunningsgewijs verwijderen bij toekomstbomen. Een en ander op basis van de plaatselijke bosontwikkeling in combinatie met monitoringsgegevens

Gewone esdoorn is een boomsoort die een dominant karakter heeft en daardoor vaak als bedreigend wordt gezien voor de biodiversiteit, zeker waar de soort zich uitbreidt. In deze studie is gekeken naar het effect tussen het voorkomen van gewone esdoorn en de diversiteit aan plantensoorten in de ondergroei. In vijf locaties zijn drie fasen van veresdoorning vergeleken: 1 het oorspronkelijke bos, nog zonder esdoorn, 2 uitbreiding met esdoorn in de stakenfase, en 3 een kern van oud esdoornbos. De diversiteit in de stakenfase bleek het geringst en bleek weer bijna tot het oorspronkelijke niveau terug te keren in oud esdoornbos, vooral in de moslaag. Ondanks het kleine aantal locaties kan uit dit oriënterende onderzoek, gesteund door literatuuronderzoek, toch deze opvallende voorlopige conclusie worden getrokken. Ouder esdoornbos scoort redelijk goed op diversiteit. Esdoorn heeft vooral negatieve effecten in de stakenfase, maar deze effecten treden waarschijnlijk ook op bij andere boomsoorten. Nader onderzoek hiernaar is gewenst. Beheerders dienen het soms geringe effect van esdoorn op de biodiversiteit goed af te wegen tegen de meestal hoge kosten van bestrijding. Uitbreiding van esdoorn (en andere boomsoorten) in open vegetaties, bijvoorbeeld de duinenkan wel een probleem zijn omdat hierdoor bepaalde vegetatietypen achteruitgaan. Ook in landgoederen en parken wordt esdoorn soms als een lastig onkruid beschouwd, meestal uit cultuurhistorisch oogpunt.

Korte samenvattingen van lezingen over: biologische grondontsmetting en de invloed van initiele inoculumdichtheid op de ontwikkeling van Verticillium dahliae in Noorse esdoorn en trompetboom; beheersing van aardappelcystenaaltjes met behulp van een vanggewas; de ecologische functie van chitinases voor bodembacterien; groene-wereldhypothese bruikbaar voor bodemfytopathologisch onderzoek?; microbiele gemeenschappen van eiproppen van Meloidogyne fallax

Gecontroleerde 'stratificatie' en een optimale luchtvochtigheid van het zaad geven een regelmatige veldopkomst

Gecontroleerde 'stratificatie' en een optimale luchtvochtigheid van het zaad geven een regelmatige veldopkomst

De biologie van de luis, het schadebeeld en de effecten op de boom