When Simply Preserving Trees Is No Longer Enough: The Challenges of Regenerating Sandy Oak Forests
The past few years of extreme drought in Hungary have made the problem of climate change — which has actually been ongoing for decades — tangible for many people. The importance of water retention is receiving increasing attention, and regulatory and practical measures have been launched to conserve water in the landscape. While the sight of drying-up lakes, canals, and agricultural areas is easily noticeable, there are also ecological processes that are less visible yet just as important. One such issue is the natural regeneration of oak forests of the Hungarian Great Plain.
Our colleagues conducted a field survey and technical consultation in the sandy oak forests between the Danube and Tisza rivers in collaboration with staff from NEFAG Zrt. The goal of this joint effort was to use scientific findings to support the conservation and regeneration of these unique forest habitats, which are in a critical state from a climatic perspective, and to contribute to the development of forest management solutions that help sustain the Great Plain oak forests amid rapidly changing climatic conditions.
The uniqueness of the Pannonian sandy forest-steppe oak forests lies in the fact that they occur only in Hungary, and their total area between the Danube and Tisza rivers is 800–1,000 hectares. All of their stands are critically endangered. They serve as the exclusive habitats for numerous forest plants (and even more animal species) in the Great Plain.
Colleagues from various disciplines at our research centre participated in the field trip, which clearly demonstrates the wide range of expertise involved in addressing these ecological challenges. As restoration ecologists, Melinda Halassy and Anna Kövendi-Jakó primarily focus on habitat restoration and natural regeneration. György Kröel-Dulay researches the ecological impacts of climate change, while Tamás Rédei examines the condition and species composition of lowland oak forests. Together, these different perspectives help us interpret the current state and future potential of habitats—in this case, sandy oak forests—as a complex ecological system.
The problem of oak regeneration had existed for a long time, but as long as most of the older trees remained alive, it did not seem particularly urgent. However, the current extreme drought conditions, which came on top of an ongoing water table decline, have created a new situation: as mature trees begin to die, it suddenly becomes clear just how crucial it is for the next generation of the forest to emerge. The biggest problem for the growth of young trees — and on this all the experts present agreed — is wildlife damage. Wild animals, in fact, have a particular fondness for fresh plant shoots and buds, but it is common for the vast majority of sprouting oak seedlings to be completely gnawed down in their first year, which drastically reduces the chances of oak trees growing and, consequently, forest regeneration. This is especially problematic in this region, where tree growth is already slow due to unfavourable climatic and soil conditions. The question of whether there will be young oak trees — that is, whether we can ultimately preserve these rare sandy oak forests — is not merely a matter of nature conservation or forestry, but a far more complex problem influenced by ecological factors at both local and global levels, one that will determine the long-term future of our forested landscapes in the Great Plain. Mixed tree species (Tatarian maple, field maple) can play an important role in the regeneration of these forests; alongside oak as the dominant species, they enhance forest biodiversity. Native shrub species (hawthorn, privet) also play a key role, as oak seedlings have a better chance of survival when protected by them.
The increasing frequency and severity of extreme climatic events raise numerous new scientific questions: how can the natural regeneration of native tree species be ensured, how can the resilience of forests be increased, and what management solutions can help them adapt to future extremes.
During our field visit conducted with forestry experts, researchers and foresters discussed the emergence of natural regeneration, habitat conditions, and wildlife exclusion as management options that support regeneration and can facilitate the development of more resilient forest stands with diverse structures. Our researchers' objective is to support silvicultural management practices for the regeneration of sandy oak forests by providing recommendations based on scientific evidence. Colleagues also discussed actively promoting the regeneration of natural forest understory, which has also been severely damaged by wildlife, as well as the need to suppress non-native woody and herbaceous plants.
This collaboration is particularly important because it creates an opportunity to link research results directly to practical forest management. The local knowledge and practical experience of NEFAG Zrt.'s experts, combined with our researchers' ecological perspective, can generate solutions that contribute to the long-term survival of the sandy oak forests of the Great Plain.