A well-functioning forest community makes the forest more stable and more efficient against harmful environmental influences.
How can biodiversity be maintained in forests affected by ash shoot dieback? Kiel University is conducting research on this in the FraDiv project together with partners from forestry and nature conservation practice. The project is funded by the Federal Agency for Nature Conservation as part of the Federal Programme for Biological Diversity with funds from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU), Ministry for Energy Transition, Climate Protection, Environment and Nature in Schleswig-Holstein (MEKUN SH).
Together with forestry companies, FraDiv develops silvicultural measures for long-term protection and development strategies for the conservation of biodiversity.
The FraDiv team is carrying out various observational and experimental approaches, with the aim to develop recommendations for action for forestry and nature conservation practice at the end of the project.
In a first approach at the observation level, FraDiv studies the effects of ash shoot dieback on forest communities at typical sites in Schleswig-Holstein. This involves recording the extent to which ash trees are affected by pests and the extent to which this damage is related to the species diversity of the stands.
In FraDivexp, we use planted mixtures of tree species to test the extent to which the biodiversity of ash-rich forest stands can be maintained or restored. We therefore combine biodiversity ecosystem functioning research with silvicultural practice. In this way, the project takes into account both the perspectives of ecological research and those of practical reforestation.
In another field experimental approach FraDiv Transplant, we are studying the influence of young ash plants’ origin and the environmental conditions at their sites of origin on the regenerative capacity of ash stands. In addition, we study the extent to which high plant densities affect survival and growth of young ash trees.
Ash-rich forests are among the most species-rich forest ecosystems in Germany. They provide habitats for a variety of fungal and plant species. A total of 29 fungal species for which Germany has
global conservation responsibility are possibly affected by ash shoot dieback, including in particular the important group of "biotroph-endophytic" fungi (called CHEGD species). Visually well
hidden, fungi spin their mycelium networks in the forest soil and in plant roots and thus contribute significantly to the functioning of forests as a "Wood Wide Web". Some plant species, that
occur more frequently in forests rich in ash trees, are already classified as severely endangered species in the Red List of the state of Schleswig-Holstein. However, the typical species
composition is a key factor for the diversity and stability of forest ecosystems.
In 2002, ash trees (Fraxinus excelsior L.) were found in Germany for the first time with withered shoots, leaf spots and discolouration of the bark. Schleswig-Holstein was the first federal state to be affected by the so-called ash shoot dieback. Ash dieback is a fungal disease in the course of which first the shoots wither and then more and more parts of the tree crown die. Black dead spots appear at the base of the trunk and indicate the trunk base necroses. As a result of the disease, most ash trees die and fall over.
Hymenoscyphus fraxineus is an inconspicuous small fungus that appears on the leaf spindle of fallen ash leaves. However, the fungus becomes dangerous for the tree in its secondary form. Its fungal filaments grow in the leading vessels of the ash trees, causing the shoots to die and weakening the tree. The weakened ash trees thus become more susceptible to further harmful organisms. So far, only a few trees have managed to defy the pathogen.
This project is funded by the Federal Agency for Nature Conservation with resources from the Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection.