Before it was a weed, today the aspen helps restore forests | iRADIO

“Spruce trees were artificially reforested here forty years ago, and the place practically lacked diversity,” describes Ivo Březina, head of the Vranov forests of the Křtiny school forestry company, on the former pasture. Previously, there was a spruce grove on the site, but in 2020 it succumbed to the bark beetle plague. “And so here it became a calamitous clearing,” he recalls of the situation four years ago.

But the foresters did not leave the situation alone. They reforested the area and this time they did not repeat the mistake from the past. They planted mainly oaks on the site, but at the same time they left nature free. “We can see after the four years how the aspen is also starting to appear here,” Březina points out.

It surpasses the other young trees in the forest. It grows quickly, has soft and relatively little heating wood, and foresters have therefore long thought of it as a “weed among the trees”. But it actually benefits the forest.

“The ecological functions of the aspen were not discussed at all before. At the same time, it creates suitable microclimatic conditions for the main economic trees, such as oak, larch, and pine,” explains Antonín Kusbach from the Faculty of Forestry and Timber at Mendel University.

Climate change helper

It is the ability of the aspen to create suitable conditions for other plants, which is a fundamental difference compared to the spruces that grew on the site before. “Ten or twenty species of grasses and herbs live under the spruce monoculture. There are up to three times as many under the aspen. Not to mention fauna, insects and microorganisms,” adds Kusbach, adding that the more organisms that live in a forest, the healthier and more resistant it is to disease. “This is exactly what is called biodiversity,” he adds.

The aspen benefits the surroundings in various ways. Insects, various mosses live in its soft and rapidly decaying wood, and its leaves decompose very well after falling and return nutrients to the soil. “The humus conditions in the soil are improving. The structure and texture of the soil is improved, so the habitat is much better prepared biologically for subsequent woody plants.”

At the same time, according to researchers, aspen is more suitable for warmer and drier climates. “It can also adapt to relative extremes, which we can see, for example, in extinct quarries,” says Kusbach.

One such – the Hády quarry – is located on the outskirts of Brno. In its area you can see rocks, here and there grass, but only a minimum of trees. But the aspen has taken hold there and is already preparing a place for other species.

“Of the conifers, I can already see a few pines, a baby maple, oaks, and among the bushes, bird’s-eye. Thanks to the aspen, we can count on the fact that the grove will grow and take up a larger area of ​​the former quarry. It is a light-loving woody plant, so it prepares the ground for other woody plants in clearings and other places,” explains the academician.

According to him, the aspen should be treated more broadly in this way, and foresters should take it into account when adapting Czech forests to ongoing climate changes. According to scientists who have studied forest stands throughout the country, aspens are actually increasing in the country. Whether this will continue and how exactly the aspen will affect nature will be known in the coming years.

Michal Šafarík

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