Tree breeding and climate change: resilient forests for the future

Abiotic threats due to climate change, as well as the emergence in parallel of new biotic agents are major concerns for foresters in Europe. The consequences for forests include reduced growth with further drastic conditions promoting even local loss of some populations or species, and a shift in some native and cultivated ranges of species. Due to human activities and fragmentation of forests, migration of trees and adaptation through other natural forces (mutation, selection) might not be possible or fast enough to cope with changes in the climate. Through active recombination and selection, forest tree breeding mostly imitates nature while greatly accelerating selection processes. Moreover, it directs them towards human requirements through selection of genetically improved varieties. As such, forest tree genetic improvement can act as an efficient way to adapt Forest Reproduction Material to new environmental conditions, assist migration of species and contribute to improving the resilience of European forests.

The contribution of Trees4Future to combating the negative effects of climate change are highlighted in the work of five of our work areas:

  • Fingerprinting and traceability of biological materials
  • Enhancement and/or deployment of medium/high phenotyping of traits
  • Phenotypic plasticity and phenology
  • Spatial modelling of provenance regions and future site suitability mapping
  • Developing modes of compatibility of modelling tools

Work Package 7: Platform for fingerprinting and traceability of biological materials

Climate change poses the biggest uncertainty for afforestation and reforestation. Forest reproductive material (FRM) planted today must not only survive climatic conditions as they used to be in the past (and for which, as a consequence, this material is best adapted), but also the more vaguely known conditions of their future lifetime, which can exceed 100 years for many tree species and localities. While the scientific community is still discussing whether to recommend policy changes in this respect, i.e. recommending material from more southern provenances or drought-resistant material, on a general basis, any such changes require a high level of confidence in the description and genetic composition of any FRM involved.

Even if foresters continue to follow a ‘business as usual’ management approach, they, and the scientific community, have a keen interest in monitoring the fate of any plantings in the wake of the climate change. Any conclusions from such monitoring depend heavily on the correct identification, labeling and classifying of the FRM involved. Maladaptations, or the contrary, better suitable material, would ideally be identified not only from past planting experiments, but concurrently with the changing climate, in exiting re-growth forests. WP7 is compiling, testing, critically assessing and recommending molecular genetic methods for identification of FRM. These methods work on the level of genes. Currently, established methods work on the basis of overall genetic similarity of parent stands (or to a degree, regions of provenance) and offspring FRM. However, as these methods analyse DNA, it is also logical to try and find factors directly responsible for the variation in growth patterns and climate response among the genes themselves, which are the determinants of the relevant inherent traits.  

Work Package 11: Enhancement and/or deployment of medium/high phenotyping of traits

The aim of this work package is to improve selection processes through the development of more efficient and more reliable evaluation of genotypes. High-throughtput phenotyping is needed for both traditional breeding and genomic selection. The focus will be on traits directly involved in facilitating tree adaptation to climate change such as phenology and tree water relation (drought resistance, resistance to cavitation, hydraulic properties of wood) but also on traits that could potentially be directly affected by climate changes such as wood anatomical and physical properties. Indirect non-destructive methodologies will test (e.g. phenology), through different forms of captors, for tree resistance to cavitation such as the use of Near Infrared Spectroscopy (NIRS). NIRS is also the basis for evaluating, indirectly, several chemical and physical wood properties. 

Work Package 3: Phenotypic plasticity and phenology

To address important decisions for climate change adaptation and mitigation we need better knowledge of plant responses to environmental changes including both genetic differentiation and phenotypic plasticity. Phenological shifts due to climate change are related to a plethora of alterations including decay (due to drought) and frosts (due to lack of acclimation), and biotic interactions. In recent years there has also been an explosion of forests pests and diseases across Europe. Since all biological process implies the interaction between genes and environment, WP3 will provide a deeper knowledge on the adaptive nature of phenotypic plasticity and the limits of phenotypic adjustment in new or extreme climate conditions that have been predicted by European climatic models. Common ‘gardens’ with known genetic entries of forest tree species, replicated over environmentally contrasted sites will be a key tool in this work package.

Work Package 8: Spatial modelling of provenance regions and future site suitability mapping

Site and climate modelling in WP8 provides the link between the projected future climate types in Europe and the suitability of genetic material, through examining the relationship between on the one hand, species, origin, and provenance growth traits and, on the other, current and future site characteristics. WP8 is developing a web framework and portal for the inclusion of models that demonstrate the suitability of genetic material related to current and future site conditions across Europe. The framework is being tested using provenance trial information for Douglas fir, European beech and ash. A second major output is the delineation of zones in Europe for tree breeding for different species. This will provide evidence of the need for collaboration between institutes and countries in Europe for tree breeding work in the future.

Work Package 10: Developing modes of compatibility of modelling tools

Climate change will not only affect which tree species can grow where in Europe but will also require adaptive capacity from within species and provenances. However, genetic understanding of variables that are important for this adaptive capacity has rarely been used in upscaling or modelling studies for European forests. WP 10 focusses on this through the combined use of 3 – 4 models. Knowledge from genetics is used firstly in a small scale model, then in a European scale plant physiological model, and then in a larger scale resource model and sustainability model. This flow of models will provide much better insight in the impacts of climate change and adaptive capacity as well as the within species adaptive capacity to climate change. So far, the work has concentrated on improving insights in capacities of the models, their requirements, and the required model parameters for exchange have been examined. Also insights in available data in genetic databases have been established.