The red oak (Quercus rubra) is a species native to the east coast of North America. In the Czech Republic, we can often meet it as an ornamental tree in parks, which decorates (as its species name suggests) with the distinctive red colour of its leaves in autumn. However, red oak is not only interesting from an aesthetical point of view, but also for its remarkable properties.
It is very resistant to low temperatures, down to -40 °C. Spring frosts will not surprise it either, because unlike our domestic oak species, red oak starts to sprout later. It is resistant to atmospheric pollution and is only minimally damaged by tracheomycosis, a fungal vascular disease that is a major threat to our domestic species. It also has a higher yield of wood compared to our oaks. To all these superlatives, it is necessary to add probably the most important one – red oak is characterized by a high tolerance to drought. This brings the red oak into focus of foresters, especially in times of climate change.
This study focused on the ability of red oak to regenerate in the first few years after planting compared to winter oak (Quercus petraea), which is one of about eight oak species naturally occurring in our territory. The experiment took place in a locality with a relatively significant lack of precipitation. Seedlings of both species were planted in the spring of 2015 and their condition was evaluated in the following four years. Attention was focused especially on the joint effect of higher temperatures and drought. There was no significant difference between the seedlings for the first two years. However, the turning point came during 2018, which was very dry and warm. It turned out that the mortality of winter oak seedlings was 29%, while red oak only 11%. The drought also affected the height increment – the year 2018 significantly slowed down the growth of winter oak seedlings, while the slowdown in red oak seedlings was only minimal.
The results of the study showed that in the area with higher temperatures and low total precipitation, red oak thrives better than our domestic winter oak. Given the current changing climate conditions, this is an important news for the foresters. However, before planting red oak, it should be taken into account that it is a non-native species and is considered invasive in many habitats. It forms a dense crown, which does not let enough light into the lower floors and thus prevents the growth of other tree and herb species. Another problem is the slow decomposition of its litter, which is also excessively acidic and can change the dynamics of soil processes. So will the advantages outweigh the disadvantages?
prof. Ing. Ivo Kupka, CSc.
Professor Kupka’s work is mainly focused on issues of forest regeneration at all levels, from the forest tree seed production and forest nurseries to the issues of afforestation, including afforestation of non-forest soils. In addition, professor Kupka engages in the "marginal" disciplines of silviculture, such as growing crops for energy use or Christmas tree plantations. Currently he also participates in the project "Optimization of the subsidy title for agricultural land afforestation".
Author: Dagmar Zádrapová