Science needs management data for a better prediction of climate change effects on socio-ecosystems

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Recolonisation by diffusion can generate increasing rates of spread

International audienceDiffusion is one of the most frequently used assumptions to explain dispersal. Diffusion models and in particular reaction–diffusion equations usually lead to solutions moving at constant speeds, too slow compared to observations. As early as 1899, Reid had found that the rate of spread of tree species migrating to northern environments at the beginning of the Holocene was too fast to be explained by diffusive dispersal. Rapid spreading is generally explained using long distance dispersal events, modelled through integro-differential equations (IDEs) with exponentially unbounded (EU) kernels, i.e. decaying slower than any exponential. We show here that classical reaction–diffusion models of the Fisher–Kolmogorov–Petrovsky–Piskunov type can produce patterns of colonisation very similar to those of IDEs, if the initial population is EU at the beginning of the considered colonisation event. Many similarities between reaction–diffusion models with EU initial data and IDEs with EU kernels are found; in particular comparable accelerating rates of spread and flattening of the solutions. There was previously no systematic mathematical theory for such reaction–diffusion models with EU initial data. Yet, EU initial data can easily be understood as consequences of colonisation–retraction events and lead to fast spreading and accelerating rates of spread without the long distance hypothesis

Distribution maps of twenty-four Mediterranean and European ecologically and economically important forest tree species compiled from historical data collections

Species distribution maps are often lacking for scientific investigation and strategic management planning at international level. Here, we present the range-wide, natural distribution maps of twenty-four Mediterranean and European forest-tree species of key ecological and economic importance in the Mediterranean basin. Data on the geographic distribution of the twenty-four tree species were compiled from over one hundred published sources, making this contribution one of the most extensive resource available from historical data. Dataset can be accessed at: https://doi.org/10.5281/zenodo.822953. Associated metadata can be accessed at: http://www.fao.org/geonetwork/srv/en/metadata.show?id=56996. These data provide key spatial information to further investigate species occurrence-environment relationships, provide a baseline to assess the future impact of climate change, identify marginal populations with specific genetic resources, among other possible applications

Marginal/peripheral populations of forest tree species and their conservation status: report for Atlantic region

This report is a synthesis of information from the national reports, prepared as part of the COST Action FP1202 Strengthening conservation: a key issue for adaptation of marginal/peripheral populations of forest trees to climate change in Europe (MaPFGR). The individual national reports can be found as part of the supplemental data to the COST action. The data compiled in this report indicate that the Atlantic area has sufficient resources in terms of knowledge and capacity to assess the potential impact of climate change on marginal and peripheral (MaP) sites within the area. Maps of vegetation, soil, climate and climatic predictions are publicly available for most countries and often are of high quality and resolution. These can be utilized to help identify MaP sites and populations in the Atlantic area. In addition, some species have been characterized genetically and the genetic data can also be utilized to identify and characterize sites. However, genetic data is not universally available and in particular may be absent for peripheral sites. There are many data sources for phenotypic traits, such as data from provenance trials but these have not been assessed for MaP populations. There may not be sufficient legislative capacity for the conservation of MaP populations in comparison to, for example, annex habitats of the EU Habitats Directive. Although some of the MaP sites lie within Natura 2000 boundaries, many are not in protected areas. If MaP populations are not characterized and conserved there is a risk of losing traits that may be of potential in adaptation to climate change. A detailed spatial analysis incorporating all of the data is needed to give a comprehensive assessment of the potential threats to MaP populations in this area

Detecting short spatial scale local adaptation and epistatic selection in climate-related candidate genes in European beech (Fagus sylvatica) populations

Detecting signatures of selection in tree populations threatened by climate change is currently a major research priority. Here, we investigated the signature of local adaptation over a short spatial scale using 96 European beech (Fagus sylvatica L.) individuals originating from two pairs of populations on the northern and southern slopes of Mont Ventoux (south-eastern France). We performed both single and multi-locus analysis of selection based on 53 climate-related candidate genes containing 546 SNPs. FST outlier methods at the SNP level revealed a weak signal of selection, with three marginally significant outliers in the northern populations. At the gene-level, considering haplotypes as alleles, two additional marginally significant outliers were detected, one on each slope. To account for the uncertainty of haplotype inference, we averaged the Bayes Factors over many possible phase reconstructions. Epistatic selection offers a realistic multi-locus model of selection in natural populations. Here, we used a test suggested by Ohta based on the decomposition of the variance of linkage disequilibrium. Over all populations, 0.23% of the SNP pairs (haplotypes) showed evidence of epistatic selection, with nearly 80% of them being within genes. One of the between gene epistatic selection signals arose between an FST outlier and a non-synonymous mutation in a drought response gene. Additionally, we identified haplotypes containing selectively advantageous allele combinations which were unique to high or low-elevations and northern or southern populations. Several haplotypes contained non-synonymous mutations situated in genes with known functional importance for adaptation to climatic factor

Geography determines genetic relationships between species of mountain pine (Pinus mugo complex) in western Europe

Aim  Our aims were to test whether morphological species of mountain pines were genetically supported in the western part of the distribution range of the Pinus mugo species complex (Pinus mugo Turra sensu lato), to resolve genetically homogeneous clusters of populations, to determine historical demographic processes, and to assess the potential hybridization of mountain pines with Scots pine, Pinus sylvestris L. Location  Populations were sampled in the Iberian System, the Pyrenees, the French Mont Ventoux, Vosges and Jura mountains, the German Black Forest and throughout the Alps. This corresponded to a range-wide sampling for mountain pine sensu stricto (Pinus uncinata Ram.) and to a sampling of the western parts of the ranges of dwarf mountain pine (Pinus mugo Turra sensu stricto) and bog pine/peatbog pine [Pinus rotundata Link/Pinus × pseudopumilio (Willk.) Beck]. Methods  In total, 786 individuals of P. mugo sensu lato from 29 natural populations, and 85 individuals of P. sylvestris from four natural populations were genotyped at three chloroplast microsatellites (cpSSRs). Populations were characterized for standard genetic diversity statistics and signs of demographic expansion. Genetic structure was explored using analysis of molecular variance, differentiation statistics and Bayesian analysis of population structure (BAPS). Results  One hundred haplotypes were identified in P. mugo sensu lato. There was a stronger differentiation between geographical regions than between morphologically identified taxa (P. mugo sensu stricto, P. uncinata and P. rotundata/P. ×pseudopumilio). Overall genetic differentiation was weak (GST = 0.070) and displayed a clear phylogeographic structure [NST = 0.263, NST > NST (permuted), P < 0.001]. BAPS identified a Pyrenean and an Alpine gene pool, along with several smaller genetic clusters corresponding to peripheral populations. Main conclusions  The core regions of the Pyrenees and Alps were probably recolonized, respectively by P. uncinata and P. uncinata/P. mugo sensu stricto, from multiple glacial refugia that were well connected by pollen flow within the mountain chains. Pinus rotundata/P. × pseudopumilio populations from the Black Forest, Vosges and Jura mountains were probably recolonized from various glacial populations that kept their genetic distinctiveness despite late glacial and early Holocene expansion. Marginal P. uncinata populations from the Iberian System are compatible with elevational shifts and long-term isolation. The causes of haplotype sharing between P. mugo sensu lato and P. sylvestris require further researc

Spatial patterns of genus-level phylogenetic endemism in the tree flora of Mediterranean Europe

Aim: The Mediterranean Basin is a major hotspot of plant biodiversity, including forest trees. Over the past centuries, Mediterranean forests have been fragmented and over-exploited, to which the threats of climate change are now added. Our aim is to better understand patterns and processes of tree biodiversity in the Mediterranean and to provide indicators complementing the traditional approaches to biodiversity conservation based on species counts and occurrences, using georeferenced phylogenetic diversity and endemism analyses in a spatial ecological context. Location: Mediterranean Europe. Methods: Using a dated phylogeny of the 64 Euro-Mediterranean tree genera, we calculated phylogenetic diversity for all 50 × 50 km2 grid cells spanning Mediterranean Europe (n = 643) and compared values with those obtained for genus-level taxonomic diversity. Then, we tested the relative influence of geography, past and present climate, and soil on tree diversity (phylogenetic or taxonomic) and its geographical turnover. Geographical patterns of phylogenetic endemism were inferred using the Categorical Analyses of Neo- and Paleo-Endemism (CANAPE) methodology. Results: We showed that phylogenetic and taxonomic diversity within and among cells are correlated and influenced by soil parameters as well as current, Holocene and Late Glacial Maximum climate. Southern Spain, Cyprus and some Aegean islands contained areas of disproportionately high phylogenetic diversity and a concentration of phylogenetic paleo-endemics, while phylogenetic neo-endemism was high in eastern Sicily. Mixed phylogenetic endemism regions were detected in southern Spain and Portugal, in the Balkans and in Crete. Main conclusions: Our phylogenetic approach provides relevant indicators for better protecting forests of the Mediterranean, encompassing past and present evolutionary processes and factors. We consider areas that show a concentration of evolutionary history manifested by high phylogenetic endemism as high priority targets for the conservation of the European tree flora.Aix-Marseille University ANR-11-LABX-006

Managing forest genetic resources as a strategy to adapt forests to climate change: perceptions of European forest owners and managers

Managing genetic diversity is of key importance in fostering resilience of forest ecosystems to climate change. We carried out a survey reaching over 200 forest owners and managers from 15 European countries to understand their perceptions of the main threats to forest ecosystems, their knowledge of forest genetic resources (FGR) and their attitude toward actively managing these resources to strengthen the resilience of forest ecosystems to climate change. Respondents perceived pests and diseases to be the top-ranking threats to forests, followed by windstorms and drought, with differences across countries. They stated to be aware of the potential offered by managing FGR and indicated that they paid attention to origin and quality in their choice of planting material. Generally, respondents showed a positive attitude in using forest reproductive material foreign to the planting site, to better match the projected future climate conditions, introducing either a new native tree species or a new non-local genotype of a species already planted (keeping the same species but changing the source of planting material). However, forest reproductive material from local sources was largely preferred over non-local material (both genetically improved and not improved). Forest managers and owners may need to be exposed to more evidence of the potential benefits deriving from active adaptation and mitigation management of FGR before implementing adaptive measures. Also, more efforts should be invested in understanding perceptions and motivations of European forest owners and managers, in order to better tailor advice on optimal measures to counteract the detrimental effects of climate change