Mushrooms as the Recycling Specialists of Our Forests

Mushrooms as the Recycling Specialists of Forests

No other living creatures have been judged so differently throughout history as the potentially immortal mushrooms. In the Middle Ages, it was even believed that mushrooms were not living creatures. Later, they were classified as plants, and today they are identified as a separate kingdom alongside plants and animals.

(Image by Andreas from Pixabay)

Mushrooms act as the most important recycling specialists in our forests. Mushrooms are beneficial organisms that break down organic materials such as dead trees, roots, leaves, and other plant parts. They are crucial to ecosystems, breaking down matter and recycling nutrients. Mushrooms can also be grown commercially on hardwood chips or sawdust, with oak being the best. Mushroom fungi have two ways to travel: growing their way across a forest or ejecting spores that can travel on animals. Mushrooms are facing threats from global change, as they are particularly vulnerable to climate change. Fungi networks can be an ally in efforts to tame global warming, but fungi lag significantly behind plants and animals in conservation efforts. Fungi can help forests absorb CO2 pollution and protect the planet from the effects of global warming, but climate change also poses significant threats to farming in the Southwest. Further, mushrooms are also experiencing biodiversity loss due to habitat loss, pollution, and the use of fungicide-laden fertilizers. 

Life History of Mushrooms

Mushrooms are a diverse group of fungi that can be found in a variety of ecosystems, including forests, grasslands, and even in urban gardens and roadsides. They play crucial roles in nutrient cycling and decomposition, making them an essential part of many ecosystems. The life history of mushrooms begins with the formation of spores, which are produced by the mushroom's reproductive structures. These spores are then transported by the wind or another method, and they can settle in an area that is conducive to their germination and development into mycelium.

The mycelium is a mass of hyphae structures that spread and thrive across the substrate. The mycelium can continue to develop and spread for years, without forming any observable fruiting bodies (mushrooms). When environmental circumstances are favorable, the mycelium will start to develop a fruiting body, i.e. the part of the mushroom that is visible above ground.

The fruiting body is composed of a stem, cap, and gills or pores on the underside of the cap. These structures are generated for reproduction, as they produce and release spores that can germinate and start the life cycle again. The mushroom will begin to decay after the spores are released and will eventually disappear, but the mycelium will carry on growing and spreading in the substrate, possibly producing additional mushrooms in the future.

Fungi do not possess photosynthetic pigments, instead, they obtain their nutrition from dead or living organisms. Thanks to their tiny, numerously formed, and easily spread spores, fungi are ubiquitous yet rarely obvious. Many can only be seen under a microscope, almost all grow hidden as a finely branched network in the respective substrate. We are most likely to notice those species that form fruiting bodies. Fruiting bodies are short-lived, spore-forming structures that we commonly refer to as fungi. The truffles, porcini mushrooms or morels revered as culinary delicacies are thus only the propagation stages of the species, similar to the apples of the apple tree.

Why Mushrooms Change Color as They Age

The color change in mushrooms is not only due to the oxidation of pigments but also due to the enzymatic oxidation of Variegatic acid and Xerocomic acid.

Reddy et al. (1985) found that the color change in mushrooms is due to the enzymatic oxidation of Variegatic acid and Xerocomic acid, which are pigments present in the mushroom. They also show that the rate of color change is influenced by factors such as temperature, humidity, and light exposure.

The study (Van Buren et al., 1999) showed that the color change in mushrooms is due to a combination of enzymatic oxidation and exposure to light. They found that the pigments in mushrooms change color as they mature and that the rate of color change is influenced by the mushroom's environment and storage conditions.

In summary, color changes in mushrooms are due to the enzymatic oxidation of Variegatic acid and Xerocomic acid, and the rate of color change is influenced by factors such as temperature, humidity, light exposure, and storage conditions.

Fungi and their importance for the natural balance

Together with bacteria, fungi form the decomposer organisms in the material cycle of our ecosystems. They decompose, for example, wood, dried leaves, fruits, horn, and fats. In the decomposition process, they return nitrogen compounds and other substances to the soil, making the nutrients available again to plants and animals. From an ecological point of view, this "recycling" task makes fungi the nourishment of the forest.

As symbiotic partners, fungi have another critical role. Particularly noteworthy are lichens as a symbiotic community with algae and mycorrhiza, decrypted as "fungal roots," as a partnership between fungi and vascular plants. Most of our trees live in symbiosis with such fungi. Mycorrhizal fungi coat the fine roots of trees, collect nutrients, and feed them to the plants along with water. In return, the fungus receives the substances necessary, i.e., mainly sugars, proteins, and vitamins.

So far, about 100,000 species of fungi have been described. However, it is assumed that up to five million species exist worldwide. This makes fungi the most species-rich group of organisms after insects. It is estimated that around one billion mycelia or spores occur in the topsoil of natural forests on an area of one square meter.

Decline in species

Both climate change and increased human activities have the potential to threaten mushroom populations and species. Climate change can alter the distribution and timing of mushroom fruiting, leading to changes in the interactions between mushrooms and their symbiotic partners, such as plants and insects. Additionally, global change, including deforestation, habitat fragmentation, and the introduction of invasive species, can alter the conditions that mushrooms need to thrive, leading to declines in both the number of species and their abundance.

In recent years, there have been reports of declines in some species of mushrooms due to these changes. For example, several species of porcini mushrooms, which are popular in Europe and are highly valued for their culinary uses, have become increasingly scarce in some regions as a result of climate change and land-use changes.

To preserve mushroom populations and species, it is important to conserve their habitats and minimize the impacts of global change, including deforestation, habitat fragmentation, and the introduction of invasive species. In addition, efforts to cultivate mushrooms for food, medicine, and other uses can help to ensure their long-term viability and to ensure that future generations can continue to enjoy their many benefits.

Further, the threats to forests mean danger to fungi. In connection with research on forest dieback, it was recognized as early as the 1970s that it is preceded by, or coupled with, fungal dieback. Many fungi react very sensitively to environmental pollution and are therefore reliable indicators of contamination. Many native fungal species are endangered or already extinct. Aiming to stop the extinction of species in the forest, it is necessary to advocate near-natural management and large-scale protected areas.