The climate crisis is not only bad for everyday trees like the spruce. Increasingly, it is also damaging rare and special species. The bog pine or bog spirke is an example. Pinus mugo rotundata, as its scientific name is, is considered by experts such as Stefan Müller-Kröhling from the State Institute for Forestry and Forestry (LWF) to be the “jewel among bog species”. Because it is not only very rare. But they are only available in the Free State and the neighboring countries from Switzerland to the Czech Republic and Saxony. In addition, there are some endangered and strictly protected animals in the area around Moor-Spirken. “The raised bog ground beetle, for example,” says Müller-Kröhling, “or the Nordic swimming beetle.” It is therefore understandable when Müller-Kröhling says that Bavaria has a special responsibility for the tree species.
The moor spirke is a rather inconspicuous tree. Lay people like to think of it as a somewhat narrow common pine. The bog spirke can be easily distinguished from the Scots pine by its bark. It is brown-grey or brown-black and never as reddish as that of the Scots pine. Pinus mugo rotundata belongs to the mountain pine complex and inhabits nutrient-poor, wet raised bogs. It grows up to 15 meters high and a maximum of half a meter thick. Its crown is cone-shaped, the needles are in bunches in pairs and are three to seven centimeters long. The cones are slightly asymmetrical and have a two-year development period.
The wood of the Moor-Spirke is hard and difficult to split, so it is not economically interesting. Nevertheless, Moor-Spirken forests have been cleared in the past. On the one hand in draining the wetlands to gain agricultural land. On the other hand, for supposed reasons of nature conservation. “The aim was to promote light-loving bog dwellers such as the raised bog yellowling,” says Müller-Kröhling. This is a very rare butterfly feeding on bog bilberry. Moor-Spirken are currently found in Bavaria on a maximum of 4000 hectares, which is just 0.16 percent of the forest area in Bavaria. At the same time, according to Müller-Kröhling, the Bavarian stock accounts for at least a third of the total occurrence.
In infested trees, the needles turn brown and die
The climate crisis hits the tree species in two ways. On the one hand, the increasingly frequent periods of extreme heat and drought are severely weakening the trees. On the other hand, it favors the fungus Lecanosticta acicola, which has only appeared in Bavaria for about 30 years and is causing more and more stocks to die off. The pest comes from North America and is considered the most dangerous pine pest of all. In infested trees, the needles turn brown, die and are shed prematurely. Long-term infestation usually leads to the death of the respective pine trees. The fungus has a very wide range of hosts, around 25 pine species are known to infest worldwide. In Germany, the pest was first discovered in 1994 in a garden in Murnau, Upper Bavaria. Six years later, the first detection in the open landscape followed – on a pine tree in a moor on Lake Chiemsee. How Lecanosticta acicola got to Europe is not clear. Müller-Kröhling assumes that it happened through the import of infected seedlings.
Instead of climate change, the silver fir, seen here as a sprout, endangers two Caucasian shoot lice species in particular.
(Photo: Manfred Ruckszio/PantherMedia)
The fungus is so aggressive that some experts now fear it could kill the bog spirken in Bavaria. Müller-Kröhling is not so pessimistic. “No pest is interested in completely killing its host,” he says. “Because that would be the end of it too.” Müller-Kröhling relies on what is known as hypovirulence. By this he means the phenomenon that the aggressiveness of a pest weakens after the first wave of infestation. “In addition, it has been observed that Lecanosticta acicola does not attack all bog spirks in an area, there are probably some that have a kind of resistance gene against it,” says the expert, “for example, it apparently leaves single ones alone.” Nevertheless, Müller-Kröhling also expects that the Moor-Spirke will not be able to hold on to all of the previous locations.
Meanwhile, more and more silver firs are apparently in danger. Albies alba is actually considered a species that is comparatively immune to the climate crisis. If only because of its deep-reaching taproot, which gives it stability in storms and other extreme weather, but also allows it to access deep-lying water supplies in the ground when it is dry. Unlike the moor spirke, the silver fir is also interesting for carpenters, carpenters and builders. Because fir wood can be used in many ways. And with a forest share of 2.5 percent, the fir is much more widespread than the moor spirke and other exotic species. But the climate crisis is increasingly turning out to be a risk for them. Two species of pine blight from the Caucasus, which were introduced to Bavaria 180 years ago, turn out to be particularly dangerous. Young firs in particular die from the pests, which are a few millimeters in size. A research project on them is therefore running at the LWF. A central question is how widespread the two Caucasian pine leaf worm species are now in the Bavarian forests.