How the forest changes with the trees

Dr. Adrian Dănescu of the Chair of Silviculture receives this year’s 6,000 euro Thurn und Taxis Forestry Prize. In his award-winning dissertation, he looked at the function of mixed and structurally rich forests, in which small and large trees of different species grow close together. Such forests are close to what nature intended and may be set to play an important role in adaptation to climate change. Dănescu investigated the influence of structural diversity on productivity, rejuvenation dynamics, and the growth of trees under drought stress, using the mixed mountain forests of the Black Forest, which mainly consist of spruce and fir. For his study, he was able to draw on extensive data gathered over the long term from experimental plots of the Forstlichen Versuchs- und Forschungsanstalt Baden-Württemberg.

Dănescu shows in his work that, in addition to the influence of species diversity, which was proven long ago, structural diversity also has a positive influence on the productivity of mixed forests. However, his findings on drought stress show that, in the fir-spruce mixed forests investigated, structural diversity has no beneficial influence on the stability of growth against drought stress. Although this result may disappoint some hopes, it is important for the development of effective adaptation strategies.

Dănescu was also able to demonstrate that the height development of young trees is influenced both by the forest roof and the structural diversity of the trees overall. In most situations, young firs were better at gaining height than young spruces. Therefore, in these forests the desired shift in the species is already taking place among the young trees; with less spruce - the big loser of climate change - and more fir, which tolerates drought and heat better.