Authors: Anna-Maria Farsakoglou (EFI), Hojka Kraigher (Slovenian Forestry Institute)
Forests in Europe are increasingly vulnerable due to different stressing factors, especially climate change and its consequences such as pest outbreaks, wildfires, floods and habitat fragmentation. These pressures affect not only forest health and productivity, but also their biodiversity and long-term viability. To respond to these pressures, forest monitoring has been incorporated into Sustainable Forest Management (SFM) strategies. It provides important information on the forest condition and ecosystem services (Forest Europe, 2020).
Traditional forest monitoring methods are focusing on the visible components of biodiversity, like tree cover, growth rates and species composition, while neglecting the third hidden power of biodiversity: genetic diversity (Kavaliauskas et al., 2018). Genetic diversity is the key to ensure forests adaptive potential, allowing tree populations to cope with environmental conditions and emerging threats (Fussi et al., 2016; Laikre et al., 2008). However, it can be heavily affected through forest management, such as timber logging, grazing, fire and non-timber product harvesting (Namkoong et al., 1996). Monitoring this invisible biodiversity layer secures the evolutionary potential of forests, yet it is still often neglected and unevenly done across species in Europe (Pearman et al., 2024).
Similar to genetic diversity, genetic monitoring can serve as the hidden power of forest monitoring and can assist in conservation and management strategies, as it tracks changes in genetic diversity in a systematic way over time (Schwartz et al., 2007).
What is Forest Genetic Monitoring?
Genetic monitoring is the measurement of changes in genetic variation and structure within populations over time, based on selected genetic parameters (Aravanopoulos, 2011). Based on more specific definitions, there are three main aims for forest genetic monitoring:
- to assess the current state of forest genetic resources and to track how they change over time, to help ensure they keep their ability to adapt and evolve in the long term (Aravanopoulos, 2016),
- to provide a practical framework for detecting adaptive evolutionary changes in response to environmental shifts (Hansen et al., 2012), and
- to track how the genetic makeup of a forest stand changes over time (Konnert et al., 2011).
This is achieved by detecting possible temporal changes in the genetic diversity, along with three evolutionary forces that actually shape genetic diversity and are associated to monitoring: selection, gene flow and genetic drift (Aravanopoulos, 2011; Bajc et al., 2020; Konnert et al., 2011). By tracking these changes we can detect what is driving them and to what extent, making forest genetic monitoring a prognostic tool and a method that supports the conservation of processes to maintain genetic diversity in natural populations ( Aravanopoulos, 2011; Bajc et al., 2020).
Why is genetic monitoring important for forests?
Genetic monitoring can serve as an early warning system. It can detect changes in genetic parameters before these changes are reflected in the population size or forest structure (F. Aravanopoulos et al., 2015; Konnert et al., 2011). This allows forest managers to act before the consequences are irreversible.
At conservation level in Europe, genetic monitoring is based on EUFORGEN’s indicators and verifiers for dynamic conservation and utilization of forest tree genetic resources (Lefèvre et al., 2020) and can add on the existing monitoring. Genetic monitoring is essential for managing Genetic Conservation Units (GCUs), which aim to conserve the forest genetic resources of tree species dynamically either in situ (at the location of the GCU) or ex situ (in another location, e.g. a botanic garden).
The European Information System on Forest Genetic Resources (EUFGIS) is a dynamic platform that hosts data on GCUs across Europe and provides a live overview of the conservation status of forest tree species. Horizon Europe projects like FORGENIUS are now building on older projects like LIFEGENMON and GenTree by integrating genetic data into digital tools and decision-support platforms.
How is genetic monitoring done in practice?
Genetic monitoring uses a system composed of criteria, indicators and verifiers. As defined earlier, the aim is the conservation of genetic diversity and the adaptive potential of forest trees over time. To achieve this, we repeat sampling of a genetic monitoring plot every 10-20 years and look at three key indicators: natural selection, genetic drift (as part of genetic variation) and gene flow/mating system. Each of these indicators is using specific verifiers, the values of which help us to detect changes that are happening at population level over time. Such verifiers include allele frequences, allelic richness, effective population size (Ne), and inbreeding coefficients (FIS) following the three levels of genetic monitoring: basic, standard and advanced (Bajc et al., 2020). More details on plot selection, establishment and maintenance as well as the fieldwork, laboratory and data analyses and cost assessment and other important elements are explained in the “Manual for forest genetic monitoring” (Bajc et al., 2020) a product of the Life+ LIFEGENMON project.
Actions needed to facilitate conservation of genetic diversity and forest genetic monitoring in practice
The following recommendations, as discussed at the conference “Forest Science for Future Forests: Forest genetic monitoring and biodiversity in changing environments” (Ljubljana, Slovenia, September 2020), should be supported to facilitate forest genetic monitoring in forestry:
- Sustainable forest management, which includes forestry practices that increase genetic diversity over the long term, should be widely practiced thus increasing forest resilience and reduce their degradation.
- The understanding and management of forest tree genetic diversity in all types of forests needs to be enhanced by additional applied research to effectively prevent the deterioration of diversity.
- Promote and facilitate an informed dialogue between science and policy makers, practitioners, and forest managers. The dialogue will help to understand the benefits of SFM, measures to increase genetic diversity, and monitoring of genetic diversity through time.
- Encourage forest managers and owners to implement sustainable forest management and further adaptive measures.
- Establish a forest genetic monitoring system and GCUs throughout Europe. Plan and coordinate the selection, management and monitoring of such areas between countries and regions.
- Include forest genetic monitoring in EU and national legislation as a tool to monitor, conserve, manage and use genetic diversity of European forests.
Conclusion
Genetic monitoring has an important role in forest resilience, conservation and long-term adaptation to climate change. It provides insights that traditional forest monitoring cannot detect, filling a critical gap in forest management and policy. For this reason and to ensure that the European forests remain resilient in the long-term, genetic monitoring should be fully integrated into national and European forest strategies.
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