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Face à la présence persistante du cerisier tardif en forêt, des gestionnaires forestiers proposent une approche sylvicole de sa gestion en fonction des impacts potentiels sur le milieux et des objectifs du propriétaire.
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Hij is de schrik van veel bosbeheerders: de Amerikaanse vogelkers. Maar het verhaal achter de boom is verrassend. Want zijn positieve eigenschappen wegen wellicht op tegen de nadelen. Dit boek belicht alle kanten en laat zien hoe we deze boom een plek kunnen geven in het Europese bosecosysteem. In dit boek wordt een nieuw perspectief geschetst op de Amerikaanse vogelkers. Zij blijkt in haar oorsprongsgebied een waardevolle boomsoort, en in onze bossen heeft vogelkers uiteindelijk ook gunstige effecten op het bosecosysteem. Bovendien worden lang niet al onze bossen massaal gekoloniseerd. De auteurs pleiten voor een genuanceerdere kijk op de vogelkers, waarbij handvatten worden gegeven voor een gedifferentieerd beheer. Het boek behandelt de introductie en bestrijding en de huidige problematiek rondom deze exoot. Ook haar invloed op bossuccessie, biodiversiteit, houtteelt en beheerstrategieën komen aan de orde. Dit boek laat zien hoe we deze exoot een plek kunnen geven in het Europese bosecosysteem, en tegelijk de bestrijdingskosten kunnen verminderen. Actuele kennis zorgvuldig en toegankelijk bijeengebracht voor specialisten in boomteelt, bosbeheerders, beleidsmakers en ecologen.
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The integration of invasive species into native food webs represent multifarious dynamics of ecological and evolutionary processes. We document incorporation of Prunus serotina (black cherry) into native insect food webs. We find that P. serotina harbours a herbivore community less dense but more diverse than its native relative, P. padus (bird cherry), with similar proportions of specialists and generalists. While herbivory on P. padus remained stable over the past century, that on P. serotina gradually doubled. We show that P. serotina may have evolved changes in investment in cyanogenic glycosides compared with its native range. In the leaf beetle Gonioctena quinquepunctata , recently shifted from native Sorbus aucuparia to P. serotina , we find divergent host preferences on Sorbus - versus Prunus -derived populations, and weak host-specific differentiation among 380 individuals genotyped for 119 SNP loci. We conclude that evolutionary processes may generate a specialized herbivore community on an invasive plant, allowing prognoses of reduced invasiveness over time. On the basis of the results presented here, we would like to caution that manual control might have the adverse effect of a slowing down of processes of adaptation, and a delay in the decline of the invasive character of P. serotina .
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Black cherry (Prunus serotina Ehrh.), a tree native of North America, was introduced in Europe in the 17th century and applied as a forest tree from the end of the 19th century onwards. It was expected to produce valuable timber, even on poor sandy soils, but it seldom did. Until the fifties, it was massively underplanted in Scots pine (Pinus silvestris L.) stands where it was believed to ameliorate the soil. Nowadays, as a consequence of its offensive reproduction strategy and important atmospheric ammonia immissions, black cherry has completely overgrown the substorey of thousands of hectares of Scots pine forest in Belgium, Germany and the Netherlands, preventing regeneration of any species but itself. Some ecological, silvicultural and forest political aspects of this issue are presented and discussed. This paper shows that the soil ameliorating properties of black cherry are doubtful and suggests that it might be an important competitor of the timber crop for nutrients and water. Furthermore, it illustrates that the abundance of black cherry forces silviculture to maintain an everlasting age class system with clearcutting and very costful black cherry combat operations (mechanical or/and chemical) during each regeneration period. It finally states that the present forest policy in Belgium, that made the option to reconvert the first generation pine stands into mixed and more uneven aged stands, only can be realized with an efficient control of black cherry. In that respect, an integrated black cherry management plan issuing a total prohibition of planting and trade, an obligatory control of seed trees in public forests and a subsidized combat in private forests, is proposed in this paper.
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Exotic invasive plants can alter ecosystem processes. For the first time in Europe, we have analysed the impacts of exotic invasive plants on topsoil chemical properties. At eight sites invaded by five exotic invasive species (Fallopia japonica, Heracleum mantegazzianum, Solidago gigantea, Prunus serotina and Rosa rugosa), soil mineral element composition was compared between invaded patches and adjacent, uninvaded vegetation. We found increased concentrations of exchangeable essential nutrients under the canopy of exotic invasive plants, most strikingly so for K and Mn (32% and 34% increase, respectively). This result fits in well with previous reports of enhanced N dynamics in invaded sites, partly due to higher net primary productivity in exotic invasive plants compared to native vegetation.
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Prunus serotina, a forest tree of North American origin, was introduced to central Europe and planted for various purposes. In the course of the centuries it was regarded as a valuable timber tree by European foresters; subsequently, as a useful non-timber species in forestry, a forest pest, a controllable weed and, eventually, as a species we have to live with. All these perceived qualities served as motives for action by humans without seeking scientific evidence for them: millions of specimens of P. serotina were planted, later millions of euros were spent in attempts at control. The species, and its changing perception through time, may be an example of the need for science-based assessments as a basis for developing policies concerning non-native plants.
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In 70 years old homogeneous Scots pine stands, bordered by a hardwood belt, an analysis was made about the spontaneous ingrowth of natural seedlings. The analysis involved especially the following points: species and stem number, influence of the hardwood belts, diameter and height distribution, age, growth and structure. From the age of 30 years, a spontaneous regeneration of hardwoods established in Scots pine stands. There are on average 7,000 plants per ha, 80 % of which are black cherry and another fair number are red oak and pedunculate oak. The regeneration has an average age of 25 to 30 years, it is uneven aged, contains several diameter and height classes and has already partially penetrated the upper stratum. The spontaneous ingrowth allows to convert in a simple way the homogeneous coniferous stands into mixed hardwood stands.
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Spontaneous natural regeneration under variable conditions on sandy soils and continental sand dunes were analysed in 5 locations in N.E. Belgium. The number of seedlings varies between 14.000 and 522.000/ha. The most prominent invading species are red oak, pedunculate oak and Scots pine. Two principal types of regeneration are recognized : homogeneous groups of oak or pine and mixtures, predominantly composed by the same species. Pioneers such as birch, willow, white poplar and wild black cherry do not play an important role. Social differentiation sets in quite early and is mainly provoked by age differences. Therefore early silvicultural intervention is advisable. The growth relationships between the species indicate that Scots pine is not in danger of spontaneous elemination by other species. Because of the density and variability of spontaneous forest regeneration, the conversion of pure pine stands into mixed forest, using group regeneration to this end, poses no real technical problems.
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Lack of information on ecological characteristics of species across different continents hinders development of general world-scale quantitative vegetation dynamic models. We constructed common scales of shade, drought, and waterlogging tolerance for 806 North American, European/West Asian, and East Asian temperate shrubs and trees representing about 40% of the extant natural Northern Hemisphere species pool. These scales were used to test the hypotheses that shade tolerance is negatively related to drought and waterlogging tolerances, and that these correlations vary among continents and plant functional types. We observed significant negative correlations among shade and drought tolerance rankings for all data pooled, and separately for every continent and plant functional type, except for evergreen angiosperms. Another significant trade-off was found for drought and waterlogging tolerance for all continents, and for evergreen and deciduous angiosperms, but not for gymnosperms. For all data pooled, for Europe and East Asia, and for evergreen and deciduous angiosperms, shade tolerance was also negatively associated with waterlogging tolerance. Quantile regressions revealed that the negative relationship between shade and drought tolerance was significant for species growing in deep to moderate shade and that the negative relationship between shade and waterlogging tolerance was significant for species growing in moderate shade to high light, explaining why all relationships between different tolerances were negative according to general regression analyses. Phylogenetic signal in the tolerance to any one of the three environmental factors studied was significant but low, with only 21–24% of cladogram nodes exhibiting significant conservatism. The inverse relationships between different tolerances were significant in phylogenetically independent analyses both for the overall pool of species and for two multispecies genera (Pinus and Quercus) for which reliable molecular phylogenies were available. Only 2.6–10.3% of the species were relatively tolerant to two environmental stresses simultaneously (tolerance value !3), and only three species were tolerant to all three stresses, supporting the existence of functional trade-offs in adjusting to multiple environmental limitations. These trade-offs represent a constraint for niche differentiation, reducing the diversity of plant responses to the many combinations of irradiance and water supply that are found in natural ecosystems.