Older trees help the endangered wolf lichen survive

The preservation of endangered species in natural habitats is significantly aided by the forest’s oldest trees, according to research led by the University of Barcelona. A prime example is the wolf lichen, currently at risk across Europe, which finds sanctuary in the ancient trees of high mountains of the Pyrenees. 

This study is the first to examine the critical role that these ancient trees play in biodiversity conservation, attributing their effectiveness to their distinctive physiology.

Wolf lichen thrives among old trees

With its limited distribution, the wolf lichen (Letharia vulpina) thrives in mature forests and among long-lived trees. This lichen, native to the American continent and found in Europe and the Iberian Peninsula’s medium and high mountain areas, is particularly associated with the Pyrenees’ oldest trees, notably the black pine (Pinus uncinata).

“These old trees are found in the most isolated places, they grow on rocks with very little substrate and show unique characteristics regarding structure and composition. Specifically, the black pine can even live for more than a millennium, and its decay would be the most important factor facilitating the presence of the lichen,” said senior author Sergi Munné-Bosch, an expert in Plant Biology at the University of Barcelona.

“Paradoxically, the worse off these trees are, the more useful they are for the ecosystem (lichen conservation). In other words, the less important they might seem as individuals because of their decline, the more important they are for the whole ecosystem.”

Centenarian and millenarian trees

According to the scientists, the best habitat for the survival of the lichen L. vulpina is the oldest trees in the forest. “In the case of centenarian and millenarian trees, the simplicity of their development, the modular growth that allows them to respond better to injury and damage, and the high tolerance to extreme conditions (water stress, extreme temperatures, etc.) are factors that explain their great longevity in the natural environment,” explained lead author Ot Pasques, a doctoral student in Plant Biology at the same university.

Slow growth favors longevity in trees

“Trees have survival limits in extreme conditions, but they can survive with little water and nutrient resources. They are able to survive extreme conditions and live longer, thanks to modular growth and compartmentalisation of the damage that can affect them,” added Munné-Bosch. 

“Slow growth, which is associated with stress responses – such as the typical cold of high mountains or drought, which is increasingly frequent in the summer – also favors the longevity of these trees.”

Necessity of safeguarding ancient trees 

The remarkable longevity of trees serves as a crucial biological factor underpinning their unique roles within ecosystems, highlighting the necessity of safeguarding ancient trees and species within secluded mountainous areas. 

According to Munné-Bosch, every member within a population holds critical importance, not just for their own group or species, but for the entire planetary ecosystem. The interconnectedness of all life means that even the aging and demise of trees contribute vitally to the maintenance of biodiversity and ecological systems.

Yet, these forest behemoths face significant threats from human activities, notably from logging. “Environmental conditions are not a problem for these trees, but unfortunately we as a species are. Only with a deep respect for nature and the life of other living beings can we preserve the extraordinary longevity of these trees. And as we have found in this study, this will also be decisive for the preservation of all biodiversity as we know it today,” the authors concluded.

More about wolf lichen

Wolf lichen is a fascinating organism that thrives in various parts of the world, particularly in mountainous regions of North America and Europe. It’s most recognizable for its vibrant yellow-green color, which makes it stand out in its natural forest environments. 

This distinct hue comes from the presence of vulpinic acid, a substance that not only gives the lichen its color but also serves as a deterrent against predators due to its toxicity.

Survival

Wolf lichen is a type of fruticose lichen, meaning it has a shrubby appearance, with branching tendrils that allow it to attach to tree bark and rocks. This growth form enables it to absorb moisture and nutrients directly from the air, which is vital for its survival in various climates and altitudes.

Uses

Historically, wolf lichen has had several uses, both practical and sinister. Its bright color was used as a dye by indigenous peoples in North America for coloring wool and other materials. 

However, its toxic properties also led to its use as a poison. There are accounts of it being mixed with meat to kill wolves and other predators, which is how it got its common name.

Ecological significance 

Today, wolf lichen is of interest to scientists and naturalists for its ecological roles and potential medicinal properties. It’s studied for its ability to produce vulpinic acid and other compounds that may have antibacterial or other beneficial effects. 

Despite its toxicity to some animals, wolf lichen is an integral part of its ecosystem, contributing to the biodiversity of the areas where it grows.

The research is published in the journal Proceedings of the National Academy of Sciences.

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