•The notion of ecosystem service has never been applied in a consistent way to anthropized ecosystems.•Human manipulations and natural ecological processes are tightly intermingled.•Services arising ...solely from ecological processes cannot be separated from the result of human manipulations.•We must jointly assess ecological services, disservices and environmental impacts of ecological manipulations.•The framework we propose constitutes a consistent way to assess and compare different practices of ecological engineering.
The notion of ecosystem service is meant to better link human societies to ecological systems and to serve has a tool for decision making. However, the notion has never been applied in a comprehensive and consistent way to anthropized ecosystems while most ecosystems are indeed anthropized. This means that in initiatives of ecosystem service assessment anthropized ecosystems are either neglected or their services assessed in a misleading way. For example, services from cultivated lands are usually valued through the value of the agricultural production, while this production highly depends on inputs (fertilizers, pesticides, non-renewable sources of energy) and human work that cannot be assimilated to ecological factors. Moreover, these practices have negative impacts such as the emission of greenhouse gases, nutrient leaching to other ecosystems or loss of soil fertility. Hence, we present here a general framework that could be used to assess the ecosystem services provided by anthropized ecosystems. This framework is based on the joint assessment of ecological services, disservices, losses of natural capital and impacts on other ecosystems. We show that this framework is required to assess different practices to manipulate an ecosystem, e.g. low- vs high-input agriculture, or different ecosystems with different levels of anthropization, e.g. manage forest vs. cropland. Indeed, ecosystems function in such a complex way that human manipulations and natural ecological processes are tightly intermingled so that services and disservices arising solely from ecological processes cannot be separated from the result of human manipulations.
We used chloroplast polymerase chain reaction‐restriction‐fragment length polymorphism (PCR‐RFLP) and chloroplast microsatellites to assess the structure of genetic variation and postglacial history ...across the entire natural range of the common ash (Fraxinus excelsior L.), a broad‐leaved wind‐pollinated and wind‐dispersed European forest tree. A low level of polymorphism was observed, with only 12 haplotypes at four polymorphic microsatellites in 201 populations, and two PCR‐RFLP haplotypes in a subset of 62 populations. The clear geographical pattern displayed by the five most common haplotypes was in agreement with glacial refugia for ash being located in Iberia, Italy, the eastern Alps and the Balkan Peninsula, as had been suggested from fossil pollen data. A low chloroplast DNA mutation rate, a low effective population size in glacial refugia related to ash's life history traits, as well as features of postglacial expansion were put forward to explain the low level of polymorphism. Differentiation among populations was high (GST = 0.89), reflecting poor mixing among recolonizing lineages. Therefore, the responsible factor for the highly homogeneous genetic pattern previously identified at nuclear microsatellites throughout western and central Europe (Heuertz et al. 2004) must have been efficient postglacial pollen flow. Further comparison of variation patterns at both marker systems revealed that nuclear microsatellites identified complex differentiation patterns in south‐eastern Europe which remained undetected with chloroplast microsatellites. The results suggest that data from different markers should be combined in order to capture the most important genetic patterns in a species.
Populations occurring in areas of overlap between the current and future distribution of a species are particularly important because they can represent “refugia from climate change”. We coupled ...ecological and range‐wide genetic variation data to detect such areas and to evaluate the impacts of habitat suitability changes on the genetic diversity of the transitional Mediterranean‐temperate tree Fraxinus angustifolia. We sampled and genotyped 38 natural populations comprising 1006 individuals from across Europe. We found the highest genetic diversity in western and northern Mediterranean populations, as well as a significant west to east decline in genetic diversity. Areas of potential refugia that correspond to approximately 70% of the suitable habitat may support the persistence of more than 90% of the total number of alleles in the future. Moreover, based on correlations between Bayesian genetic assignment and climate, climate change may favour the westward spread of the Black Sea gene pool in the long term. Overall, our results suggest that the northerly core areas of the current distribution contain the most important part of the genetic variation for this species and may serve as in situ macrorefugia from ongoing climate change. However, rear‐edge populations of the southern Mediterranean may be exposed to a potential loss of unique genetic diversity owing to habitat suitability changes unless populations can persist in microrefugia that have facilitated such persistence in the past.
We examined large-scale patterns of morphology, genetic structure and ecological correlates of Fraxinus excelsior and the closely related species Fraxinus angustifolia in France, in order to ...determine the degree of hybridization between them. We sampled 24 populations in two putative hybrid zones (Loire and Saône), and five control populations of each species. We measured foliar characteristics of adult trees and used five nuclear microsatellites as molecular markers. Canonical discriminant analysis indicated that the two species differ in morphology, but that intermediate types are common in the Loire region but less frequent in the Saône region. Bayesian population assignment identified one F. angustifolia and two F. excelsior gene pools. Most Loire individuals clustered genetically with the F. angustifolia gene pool. In contrast, the Saône region presented individuals belonging mostly to F. excelsior pools, although the F. angustifolia type was frequent in certain populations. The lowest FST values were found between the Loire and F. angustifolia controls that also exhibited no significant isolation by distance. The proportion of the F. angustifolia gene pool in each locality was negatively correlated with winter temperatures, suggesting that a cold climate may be limiting. Hybridization is probably favoured by the intermediate climatic conditions in the Loire region that allow both species to occur, but is somewhat hampered by the harsher winters in the Saône area where morphological introgression has apparently not yet occurred.
Common ash is a temperate forest tree with a colonizing behaviour, a discontinuous spatial distribution and a peculiar and poorly known mating system. Microsatellite markers were used to study the ...genetic structure in natural populations of common ash. Twelve populations located in northeastern France were analysed at five loci. Levels of genetic variability within and among stands were estimated for the seedling and adult stages. As expected for a forest tree, our results reveal high levels of intrapopulation diversity and a low genetic differentiation between stands. However, a general and significant heterozygote deficiency was found, with a mean FIS of 0.163 for the seedlings and of 0.292 for the adult trees. The different explanations for such an excess homozygosity are discussed: a nonMendelian inheritance of alleles, the presence of null alleles, a Wahlund effect and assortative mating.
This report is devoted to the studies of multiphonon excitations in nuclei, it contains in fact two reports: an experimental one presenting a review of the observation of multiphonon excitations and ...a theoretical one centered on the description of such states. The present knowledge about giant resonances in nuclei is first briefly presented and the relative merits of different probes to excite such states are illustrated. The existence of giant resonances built on excited states is stressed. In this context, multiphonon states, i.e. a giant resonance built on top of other giant resonances, are expected. Several paths can be followed to obtain experimental evidence for multiphonon states: inelastic nuclear and Coulomb excitations and charge exchange reactions. The status of the search for isoscalar multiphonon excitations by means of the strong nuclear potential produced by heavy ions is presented and novel experimental signatures of the double excitation of the giant quadrupole resonance are reported. Coulomb excitation induced by relativistic heavy ions is presented as another fruitful approach to the study of the double dipole and recent experimental results using the very selective (
π
+,
π
−) double charge exchange reactions are shown and discussed. Calculations for these different excitation mechanisms are presented.
A review of the theoretical descriptions of the properties of the multiphonon states is then presented. Hydrodynamical and phenomenological models are first discussed. The mean-field approaches are summarized. The random phase approximation is introduced to discuss giant resonances while several extensions of the meanfield concepts are presented in order to deal with large amplitude motion and multiphonons. Finally, boson mapping techniques are used to introduce a general treatment of multiple excitations. The different approaches consistently predict that such multiple collective excitations in nuclei should closely follow a harmonic pattern. Therefore, the energy of the phonons is predicted to be additive. This conclusion allows to discuss the properties of the width of the multiphonon strength in a simple manner and the observed width is predicted to be close to the quadratic sum of the single-phonon widths.
General conclusions are drawn and new prospects are discussed.
The risks of gene flow between interfertile native and introduced plant populations are greatest when there is no spatial isolation of pollen clouds and phenological patterns overlap completely. ...Moreover, invasion probabilities are further increased if introduced populations are capable of producing seeds by selfing. Here we investigated the mating system and patterns of pollen-mediated gene flow among populations of native ash (Fraxinus excelsior) and mixed plantations of non-native ash (F. angustifolia and F. excelsior) as well as hybrid ash (F. excelsior × F. angustifolia) in Ireland. We analysed the flowering phenology of the mother trees and genotyped with six microsatellite loci in progeny arrays from 132 native and plantation trees (1493 seeds) and 444 potential parents. Paternity analyses suggested that plantation and native trees were pollinated by both native and introduced trees. No signs of significant selfing in the introduced trees were observed and no evidence of higher male reproductive success was found for introduced trees compared with native ones either. A small but significant genetic structure was found (φft=0.05) and did not correspond to an isolation-by-distance pattern. However, we observed a significant temporal genetic structure related to the different phenological groups, especially with early and late flowering native trees; each phenological group was pollinated with distinctive pollen sources. Implications of these results are discussed in relation to the conservation and invasiveness of ash and the spread of resistance genes against pathogens such as the fungus Chalara fraxinea that is destroying common ash forests in Europe.
Fraxinus excelsior (L.) is an anemophilous (wind-pollinated) deciduous tree, distributed throughout Europe and Asia Minor. Its wood is still favoured by European foresters, as indicated by ...improvement and plantation programmes. These programmes rely increasingly on identification tools such as molecular markers in order to reduce ambiguities and to identify accurately elite material to be propagated. To complete the few existing microsatellite loci (Brachet et al. 1999), this study reports the characterization of 10 new microsatellite markers in Fraxinus excelsior (L.) and shows their potential for further use in various species of the Oleaceae family, which contains the important forest genus Fraxinus as well as the olive genus Olea and many ornamentals.
Proton elastic and inelastic scattering angular distributions to the 2
+
1 and the 3
−
1 states for the neutron-rich nucleus
20
O were measured with a secondary beam using the MUST silicon strip ...detector array. Data for
18
O were also obtained for comparison. A phenomenological analysis has been used to deduce the deformation parameters
β
p,p′ for the collective excitations. Matter and transition densities were generated from self-consistent QRPA calculations. DWBA calculations using microscopic optical potentials obtained with these densities and the JLM interaction are compared to the data. The isovector character of the 2
+
1 state in
20
O is confirmed and predictions are discussed for the properties of the heavier neutron-rich oxygen isotopes.
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