• Sun. Sep 26th, 2021

Forest of the future: dance of the fireflies


Jun 9, 2021

The National Park Thayatal is the smallest in Austria and the most hidden. Here, not only is it preserved, but also experimented with.

Paradise for fireflies and people: the Thayatal National Park, Lower Austria Photo: Volker Preusser/imago

Yes, what did we actually expect? Bats, perhaps, like the lesser horseshoe bats we had just accidentally disturbed in the keep of the Kaja ruin high above the Thayatal, where the night hike started. A dormouse, as it is said to have crossed the path of ranger Bernhard Schedlmayer shortly before. Or even one of the so rare European wild cats, which had long been considered extinct in Austria, when they were sighted again here in the national park a few years ago.

But what suddenly surrounds us in the twilight between the trees is quite magical. First it’s just a small point of light, like a shimmering reflection on a drop of water. Then a second, a third, a dozen, suddenly yellow, light green sparkles everywhere. Hundreds, perhaps thousands, of fireflies are here on the banks of the quietly rippling Kaja creek for their last rendezvous, dancing the dance of their lives.

Although the little worms, which are actually beetles, can also produce a soft glow as eggs and larvae qua bioluminescence, it is only when they go in search of mates in their last days to reproduce that they really shine brightly and transform their surroundings into a fairytale world.

In the Thayatal, fireflies find ideal conditions. Conditions that are increasingly rare elsewhere. Damp meadows and deciduous forests, for example, a natural stream and river banks, organic darkness, hardly polluted by artificial light, in which male and female beetles can also find each other.

The incredible diversity

Schedlmayer says two things are characteristic of Austria’s smallest national park, at 1,360 hectares. "The diverse meadow forms and the canyon forest." The lanky ranger, who always seems to have all his senses switched on at the same time, doesn’t show that he was once a young manager in the economy in the distant past.

Now he shows visitors to the Thayatal National Park the incredible diversity. Of the 2,950 plant species that have so far been identified throughout Austria, at least 1,290 are found in the Thayatal. The same is true for insects, birds or mammals.

And for crayfish. Under the next bridge, a single noble crayfish in the Kajabach stretches out its claws, which are colored red from below, in the light of the flashlight. In the past, the rivers in Lower Austria were full of these arthropods, says Schedlmayer. Today, the noble crayfish is one of the highly endangered species and has found one of its last refuges here in the northern Waldviertel.

"Walk with each other and be surprised," is Schedlmayer’s philosophy. The many small discoveries almost make you forget that the main actor of the National Park Thayatal is actually the forest. 92 percent of the area is covered with trees, the few gaps are used by fat and wet meadows, by heath and dry grasslands, most of which were created by sheep and goats grazing there in the past and are now among the most important biodiversity hotspots of all.

Christian ubl, National Park Director

"The core idea is to let nature be nature".

Even the forest is by no means monotonous. Along the winding loops of the Thaya, the landscape is constantly changing. The fact that nature is so charming is also due to the fact that two climatic zones meet here. The west is dominated by the continental cool climate, which red beech, sycamore maple, yew and even mountain elm trees like. In the eastern part, characterized by the dry and warm Pannonian climate, oak and hornbeam forests can be found.

"The core idea is to let nature be nature," says National Park Director Christian ubl. In the early days of the protected area, however, that wasn’t quite true. For initially, there was by no means only primary forest here, despite the difficult slopes for forestry. As in many other regions, forest owners had long relied on fast-growing conifers such as spruce, Douglas fir, larch and pine. "All introduced, non-local tree species that are not at all adapted to the local climate," ubl says.

Important habitats

Forestry use itself has also hindered development. Trees whose wood is to be used are felled as soon as they stop growing, i.e. after 20 or 30 years. "The forest was missing two-thirds of the trees’ life cycle," ubl says. That’s because the massive crowns of older trees and the deadwood of dying trees are also important habitats for lichens, fungi and animals.

Nature had a bit of a head start even before the canyon was placed under protection. Because the system border ran here until 1989, the area had been closed for a good four decades and was only allowed to be used for agriculture on the periphery. "In principle, that anticipated the national park idea," ubl says. The Austrian conservationists were able to build on this just as much as their colleagues on the Czech side, whose NarodnI park PodyjI on the left bank of the Dyje is not only almost five times larger, but was also founded nine years earlier.

Although both administrations work together and ultimately pursue the same goals, the paths are surprisingly different, ubl says. On both sides, he says, they started by getting the non-natural conifers out of the forest, "but the Czechs then mapped the whole forest and actively planted the trees they thought belonged there to make it go faster." Now it also becomes clear what ecologist Thomas Wrbka meant by the "concept for the forest": In the National Park Thayatal, one allows nature time to develop itself and waits to see what asserts itself in the gaps.

Perhaps the most exciting project at the moment deals with climate change. Forestry experts and forest owners worldwide agree that forests must be transformed if they are to cope with the consequences of global warming.

Which species will get through

But what exactly needs to happen, what will the forest of the future look like, which trees can withstand rising temperatures, extreme weather and new pests? That’s being studied in many places. Some are relying on species from areas that are already drier, others on trees that are basically deep-rooted, often a mixture of hardwoods and conifers.

In the Thayatal, in cooperation with the Federal Forest Research Center and the University of Natural Resources and Applied Life Sciences, it was discovered that the sessile oak native to the area is particularly well adapted to hot and dry environmental conditions. It grows here on steep slopes exposed to the sun without protection, where it has to endure a lot.

ubl puts his hand on the trunk of a mighty tree. "This oak has experienced a lot," he says, enumerating: minus 26 degrees and 25 days of closed ice cover in 1956, 39 degrees plus a year later, only 290 milliliters of precipitation in 1978, floods and heavy rain in 2006. "In 2014, ice accumulated so heavily on the branches that many trees fell – the ones that are still there now were successful," ubl concludes.

This tree is still standing and therefore now wears a white cord. The botanists have marked a total of 400 free-standing large sessile oaks in this way and taken thin cores from them. Analyses are to show which 100 of them have coped best with the extreme conditions. Their acorns will be collected and used as planting material for Austrian forestry. We will not live to see the results, what will become of the seedlings and how they will change the forest will probably only be seen in 100 years.

The changes that have taken place in the Thayatal over the last 20 years, on the other hand, are already very clear on a small scale. In just a few square meters, ubl points to young shoots: a hazelnut, a Cornelian cherry, spindlewort, a maple. "The species that are best adapted to the site come through."

What these are becomes apparent when looking down from the ruins of Kaja Castle, where the bats are allowed to hang out undisturbed by visitors* on weekdays: lots of foliage, various shades of light green, and colorful patches of meadow in between. "Of 120 hectares of non-natural woods, 4 hectares are now left," ubl says. And the national park team wants to have those under control by 2030, too.

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