Forest Research Centre, INIA, Spain Coordinator: Santiago Gonzalez-Martinez
Desertification Research Centre, CSIC/University of Valencia, Spain
Biodiversity, Genes and Communities Unit (BIOGECO), INRA/University of Bordeaux, France
Ecology of Mediterranean Forests Unit (URFM), France
Faculty of Biology, Philipps-University of Marburg, Germany
Dept. of Ecology and Genetics, Uppsala University, Sweden
Forests cover approximately 25% of Europe and are a key reservoir of genetic diversity that can play a decisive role in climate change mitigation through adaptation. The response of forest trees to current and future environmental pressures depends on the levels of genetic variability (standing genetic diversity) that they carry. The LinkTree project investigated how trees adapt to new environments, by focusing on:
1. Identifying genes playing a role in tree adaptation to climate change or environmental hazards, for instance through drought/cold tolerance or response to fire;
2. Providing detailed understanding on how the genetic variability of forest trees may confront and respond to rapid environmental change and on the implications for forest functioning and dynamics;
3. Assessing how management of tree genetic variability by forest habitat managers can increase forests’ adaptation capacity to environmental changes.
LinkTree gathered six research groups from five countries to analyse the effects of environmental changes on tree standing genetic diversity. To generalise results, it also used simulation models at both local and wider scales, accounting for predicted climate change and focusing on a range of tree species ecologically and economically important for Europe. More precisely, the approach was to:
1. Identify and characterize genes of targeted tree species involved in drought resistance, cold tolerance and phenology using high throughput sequencing and genotyping methods;
2. Analyse genetic variability and its ecological context at local and large scales in order to understand and assess the adaptation capacity of European forest trees to climatic stresses and its determinants;
3. Use eco-genetic models to provide forest managers and other stakeholders with better information on the genetic make-up of trees and their adaptive potential, thus helping them to sustainably manage forest tree populations in a changing environment.
• LinkTree demonstrated that forest trees maintain a very high genetic variability not only across Europe and across different landscapes but also at the very local scale, because of micro-scale and year-to-year environmental and biotic variations.
• Simulations carried out in Link Tree demonstrated that local climate gradients can generate genetic adaptation as “fast” as in five generations, a timeframe compatible with moderate climate change scenarios, which could thus prevent local tree extinctions.
• The LinkTree team found that gene networks and alleles responsible for local adaptation in one place, such as those involved in drought resistance, are different from the ones involved for the same trait in another habitat. This is very important for assessing the merit of transferring genetic material form one place to another as a climate change mitigation measure and suggests that promoting the evolution of local genetic material may be a better option .
• LinkTree demonstrated that forest management strategies can foster, increase or reduce genetic diversity by affecting tree density and grouping, and that management strategies at landscape scale should aim at maintaining genetic diversity for long term adaptation.
Studying the genetic effect of environmental gradients in forest tree populations across Europe, LinkTree contributed significantly to understanding the effects of local adaptation at the genomic level and the determinants of demography versus natural selection on patterns of allelic variation*. LinkTree provided a wealth of data on candidate genes showing gradual changes of allele frequencies at large, range-wide geographical scales and at small spatial scales over local gradients (see figure), contradicting theoretical models that predict abrupt shifts of allele frequencies within a short distance over environmental gradients. LinkTree also highlighted the need for new research linking genomic, phenotypic and environmental information to better understand the spatial scale and pace of genetic adaptation, particularly in the context of global change.
* Savoleinen et al. (2013) Ecological genomics of local adaptation. Nature Reviews Genetics 14: 807-820
• LinkTree partners worked closely – including during the planning of the project – with a number of stakeholders, i.e. national or local authorities from several countries and international policy programmes such as EUFORGEN.
• A number of NGOs, protected area managers and policy-makers were directly involved in LinkTree and listed major challenges faced by forests under climate change in Europe from their own perspective.
• National forest managers were approached in each of the 5 countries to conduct field experiments and sampling of collections. They notably provided information that led to the selection of the test sites used in the project.
LinkTree produced a set of tools adapted for use by forest stakeholders in a proactive manner by providing:
• Several publications in national practitioner journals;
• A set of criteria and indicators for forest management;
• A Public-awareness interview and article on “Forest adaptation to future environments” (http://www.igv. fi.cnr.it/linktree/data/p96-98_Linktree-HD.pdf);
• A policy brief for European and national policy-makers, and a movie presenting the project, both supported by BiodivERsA (https://www.biodiversa.eu/news/
• “Forests and global change: what can genetics contribute to the major forest management and policy challenges of the 21st century?” This document was prepared jointly by the project’s scientists and stakeholders and provides insights on the role of genetics in European forests’ response to climate change (Fady et al. (2015) Regional Environmental Change 15(6): 1-13).
• FAO’s “State of the World’s Forest Genetic Resources 2013”: the LinkTree team directly contributed to this thematic study of the FAO, in particular for the part on “Indicators of forest genetic diversity, erosion and vul- nerability“ (see also Graudal et al. (2014) Forest Ecology & Management 333: 35-51).
• Technology transfer: the LinkTree team transferred molecular techniques from the project for the charac- terisation of forest tree reproductive materials to the Spanish Ministry of Agriculture, Food and Environment.