FW-R-2: Conservation of forest-genetic resources | Umweltbundesamt

FW-R-2: Conservation of forest-genetic resources

Up until 2017, it was possible to expand the in-situ and ex-situ conservation resources. The data of the most recent survey, however, are not yet available. The conservation stands ensure that the genetic diversity is retained in respect of both frequent and scarce / rare tree species. This serves the purpose of establishing the basic prerequisites for conserving the adaptability of forests.

Genetic diversity increases the adaptation capacity

Forest transformation is intended to build up mixed and climate-resilient stands. The objective is to promote above all resilient autochthonous tree species and to ensure that forest transformation takes care to ensure as far as possible, that new trees originate from local, site-adapted stock. An essential element for the adaptation to present and future site condition is intra-species genetic variation. This is true, above all, for site-bound, long-lived organisms such as trees. Genetic variation results from processes of molecular-biological and population-genetic processes. Processes of adaptation to local environmental conditions produce populations with a characteristic genetic composition which differentiates from other populations of the same species. The loss of genetic diversity is an important indicator for the loss of adaptability of populations.

Progressive climate change with ever-more extreme weather events and associated impacts increase the selection pressure on forest stands. It is only the genetically adaptable individuals – in other words, individual trees – which can survive, grow and reproduce within greater populations. In view of the multitude of interactions and the dynamics of individual factors it is not possible to predict to which individuals or populations this will apply. This dilemma can only be resolved by maintaining a sufficiently large number and diversity of potentially adaptable individuals. Hence, the monitoring and maintenance of genetic diversity and the genetic system continue to be the focus of measures aimed at conserving genetic resources. Of particular importance is the ongoing recording of various spatial occurrences of a multitude of species in vigorous, adapted and potentially adaptable tree and shrub populations in Germany.

The measures taken to conserve genetic resources for silvicultural purposes can be differentiated as in-situ and ex-situ respectively. The objective of in-situ measures is to conserve – as dynamically as possible – the relevant genetic resources as so-called ‘gene conservation objects’ on the sites where they occur and in the environmental conditions prevailing at that site. Both natural and artificial regeneration safeguard and transmit genetic information to the next tree generation. Particularly endangered species or varieties are kept ex-situ in specially established archives and, where necessary, in ex-situ seed plantations. The ex-situ measures are static measures with the objective to safeguard the current character of genetic diversity. This includes taking measures for the long-term storage – under controlled conditions – of seed material, pollen, plants or plant components as carriers of genetic information. Such conservation strategies are characterised by requiring differing amounts of surface area, investment costs, utilisation and monitoring. This is why expensive ex-situ conservation is less frequently used than in-situ conservation. Seed plantations serve dual purposes: the production of genetically diverse seed materials and as the foundation required to strengthen and transform forests adapted to climate change.

In Germany the individual Länder have the remit for gene conservation measures. It is the Länder’s individual concepts which create the framework for the conservation of genetic resources for the silvicultural measures to be taken. At Federal level the genetic information on the indication of all genetic conservation objects is collated in the National Inventory of Forest Genetic Resources (FGRDEU). The data are updated and supplemented every few years.

A straight-forward interpretation of changes in number and surface area of genetic conservation objects in Germany is not possible. This is because there are numerous crucial factors which determine genetic adaptability to climate change. The number of genetic conservation objects per tree species and the size of conservation areas can only convey a rough idea. In principle, the interpretation of these data requires detailed silvicultural knowledge and the application of specific indicators (such as conservability and ecological conservation index). On the other hand, the number of overall genetic conservation objects does not provide any clues regarding the size of a population. For example stating the number of ‘in-situ conservation stands’ for rare and secondary tree species would exaggerate the conservation status of small population numbers or low numbers of individuals. Besides, genetic inventories which would meet the principles of silvicultural monitoring are still in their infancy. It would therefore be unreasonable to apply a one-dimensional principle such as ‘the more genetic conservation objects, the better’, because for every tree species there is a meaningful extent of genetic conservation stands beyond which any increase in surface area or amount of stored genetic conservation objects would not result in improving the safeguarding conditions.

In general, it can be stated that distinct progress has been made regarding the conservation of forest-genetic resources: The designation criteria for genetic conservation objects are homogeneous nationwide; increasingly genetic markers are applied in the characterisation of forest-genetic resources, and nationwide pilot monitoring programmes have been established in respect of population-genetic issues. These developments provide an additional basis for assessing the genetic adaptability of trees in climate change conditions.

In Germany the area used for in-situ and ex-situ genetic conservation objects increased up until 2017. Only the terrain of in-situ stands decreased slightly between 2010 and 2012. As far as the more frequently occurring forest tree species are concerned, for which the Forest Reproductive Material Act (FoVG) governs production, trading, as well as import and export of forest reproductive material, the area of in-situ stands increased from 12,681 to 32,405 ha between 2004 and 2017. The data captured in the latest data collection with declaration date 31-12-2022 did not come to hand in time for the due date of this Monitoring Report. It was therefore not possible to update the time series. Rare or endangered tree species are not governed by the FoVG. They will play a more important role as alternative tree species in climate change. For pubescent oak, wild service tree, true service tree, crab apple, wild pear, yew, field maple, green alder, grey alder and bird cherry, data were collected in a systematic and homogeneous manner. The factors examined were topographic aspect, population size, vitality status and age structure of the occurrences. By 2017, the in-situ stands reported had been expanded to roughly 4,560 ha. The area of cultivated stands and seed plantations established for genetic conservation (ex-situ)also increased – from 1,777 ha in 2004 to 2,470 ha in 2017. In this case too, the next Monitoring Report will present current data.