The Relationship Between Plants and Fungi: Mycorrhizal Networks

When we think of fungus, some of us might automatically conjure images of an insidious mold, making its way into our homes or between our toes! Foodies, however, might think of culinary delights, rare mushrooms bursting with unique flavor that elevate dishes to the next level. In either case, both impressions are somewhat one-dimensional. The truth is, our world’s myriad fungi are so much more than mold and mushrooms, they are amazing lifeforms that live almost symbiotically with the plants, animals, and microorganisms around them.

There are many intricate relationships that exist within different ecosystems. We know how predators and prey interact, we even know how microbes interact with decaying plants and animals. But the most fascinating of these interwoven ecological relationships often go unnoticed. Indeed, the most vital connections within our planet’s ecosystems usually occur beneath our feet, in a space where plants and fungi engage in an astounding partnership that sustains life in so many of its forms.

We are speaking, of course, of mycorrhizal networks in which the intermingling of plant and fungi results in a symbiotic partnership. Mycorrhizal networks play a crucial role in the health of ecosystems, influencing plant growth, nutrient availability, and community dynamics. In this article, we will delve deep beneath the soil to examine these networks. We will examine the complexity of these relationships, compare the different types of mycorrhizal associations, and discuss their ecological significance. We will also briefly touch on the implications of disrupting these networks; something our species can’t seem to help but do these days.

Understanding Mycorrhizae

The term “mycorrhiza” originates from the Greek words “mycos,” meaning fungus, and “rhiza,” meaning root, thus the term mycorrhizae refers to specialized associations between fungi and the roots of nearby plants. While some readers might be mildly familiar with this concept, it’s likely that many of you haven’t heard that it isn’t just some plants that engage in this type of symbiotic relationship with fungi, it’s all plants. This relationship enables plants to access nutrients and water more effectively. The fungi, meanwhile, receive carbohydrates that the plants produce through photosynthesis.

There are two primary types of mycorrhizae include:

Ectomycorrhizae

Ectomycorrhizae (ECM) form a sheath around the root tips of pines, oaks, birches, and many other trees. The fungal hyphae penetrate the spaces between the tree root cells, though they don’t invade the cells themselves in any way. Instead, the external association winds up creating a dense network of fungal filaments that can then extend far beyond the root zone, increasing the root surface area for nutrient absorption.

Arbuscular Mycorrhizae

Arbuscular mycorrhizae (AM) are similar, though they don’t just work with trees. AM aren’t a s picky about which roots cells they choose to link up with. These mycorrhizae penetrate the root cells of most terrestrial plants, forming structures called arbuscules within those cells. Arbuscles facilitate the exchange of nutrients between the plant and fungi. AM fungi are particularly important for herbaceous plants and many agricultural crops.

In both cases, these types of mycorrhizae play a vital role in the health of ecosystems, influencing plant nutrition, maintaining soil structure and stability, and even fascinate further interactions between other local plant species.

The Benefits of Mycorrhizal Associations

We have already established that the symbiotic interaction better plants and fungi can help both to grow more efficiently, but there are far more benefits than that at work here. You can read about several of these benefits below:

Enhanced Nutrient Uptake

Mycorrhizal associations is improved nutrient uptake for both the plants and fungi themselves. As the fungi extend their hyphae into the soil, they latch on to the root systems of nearby plants, effectively extending the root surface area for them both. More surface area equates to better nutrient absorption. One example is phosphorus, an essential nutrient often limited in soils. The mycorrhizal fungi themselves are particularly effective at mobilizing this nutrient, thereby making it more available to plants.

Research has shown that mycorrhizal fungi have the ability to increase phosphorus uptake by several times compared to non-mycorrhizal plants. This adaptation is particularly important in nutrient-poor soils, where phosphorus is often bound to soil particles and therefore unattainable by local plantlife.

Improved Water Absorption

Mycorrhizal networks are thirsty little buggers and they help the plant roots that they are attached to drink water more effectively as a result. The extensive hyphal networks of fungi enhance water absorption capabilities because of their ability to access water from deeper soil layers that plant roots simply cannot reach. This increased reach and water availability helps the symbiotic plants survive even during drought conditions.

Studies indicate that plants that are a part of mycorrhizal networks exhibit greater drought tolerance than most of their non-mycorrhizal cousins. The very nature of this adaptation allows plants within these symbiotic partnerships to maintain turgor pressure and stay alive during periods of limited water availability.

Soil Structure and Stability

Fungal hyphae are capable of bringing soil particles together, thereby contributing to soil structure and stability. This is because the large fungal and plant root networks take up a lot of space, worming their way through the soul and forming aggregates that improve soil aeration, water infiltration, and root penetration. This process is essential for maintaining healthy soils and preventing erosion because they allow for soil cohesion and water retention.

Disease Resistance

Some people might think of intermingled fungal tendrils invading a plant’s root’s system as something of a disease in and of themselves, but mycorrhizal associations have actually been shown to enhance plant resistance to pathogens. Research has shown that the presence of mycorrhizal fungi can stimulate a plant’s immune response, making it more resilient to root rotting diseases like Phytophthora, Fusarium, or any other disease that is normally caused by soil-borne pathogens. In essence, mycorrhizal networks that are attached to plant roots form a sort of protective buffer for agricultural crops and natural ecosystems alike.

Mycorrhizal Networks: The “Wood Wide Web”

Beyond the benefits borne of individual plant-fungal relationships, mycorrhizal networks create a vast underground communication and nutrient exchange system within plant ecosystems. This is sometimes referred to as the “Wood Wide Web,” and it enables plants to share resources and even information, which influences community dynamics and increases the health of ecosystems.

Resource Sharing

Mycorrhizal networks allow plants to share nutrients and water not only with their attached fungal partners, but also with neighboring plants! When plants are under stress or in need of nutrients, neighboring plants or those that are part of the network can share those things. This example of mutualism promotes cooperation within ecosystems. It enhances the survival and growth of plant communities, fostering biodiversity. There are even some ecosystems where plants act as “nurse plants,” providing support to less vigorous or young plants through the mycorrhizal network.

Communication and Signaling

There is a prevailing theory that plants and fungi are not capable of communicating in any way that laypersons might consider to be meaningful. This so-called fact has been disproven many times over, as herbivory often allows plants to communicate warnings to one another in various chemical ways. Mycorrhizal networks give further proof. In fact, these networks often facilitate communication among plants in ways that are not seen in other forms of “non-sentient” life. When a plant is attacked by herbivores or pathogens, it often releases chemical signals that then make their way into the mycorrhizal network. This alerts neighboring plants to prepare their defenses. This signaling mechanism is unique enhances the overall resilience of plant communities.

The Role of Mycorrhizal Networks in Ecosystem Health

Biodiversity and Ecosystem Resilience

By now, you can probably understand how mycorrhizal networks can play a critical role in promoting biodiversity by supporting diverse plant communities. At the same time, they also enhance ecosystem resilience through soil stabilization, nutrient sharing, and other such mechanisms. Many scientists and conservation organizations have begun incorporating mycorrhizal fungi into replanting efforts. These efforts have been largely successful and have proven to enhance plant survival and growth. By promoting mycorrhizal associations, restoration ecologists can improve the resilience of ecosystems being rehabilitated after disturbance.

Carbon Sequestration

Like so many other essential lifeforms on our planet, mycorrhizal fungi contribute to carbon sequestration by facilitating the storage of carbon in soil. Plants photosynthesize and convert atmospheric carbon dioxide into organic compounds, which are then transferred to the mycorrhizal fungi beneath the soil. This process not only supports fungal growth but also contributes to the formation of soil organic matter, helping to mitigate climate change by reducing carbon that would otherwise be in our atmosphere.

Threats to Mycorrhizal Networks

Like so many of our plant’s lifeforms, mycorrhizal networks face numerous threats from human activities and environmental changes.

Habitat Destruction

Habitat destruction is a big problem affecting mycorrhizal networks. This destruction is wrought by a combination of agriculture, urbanization, and deforestation. These human-derived problems can severely impact mycorrhizal networks, destroying native plant species and tearing apart important symbiotic relationships. This in turn leads to a decline in ecosystem health and biodiversity.

Soil Degradation

Unsustainable agricultural practices has been known to degrade soil by means of excessive tilling, monoculture, and chemical inputs. These factors can diminish mycorrhizal fungi populations, which rely on healthy soil in order to function. Without proper soil, even powerful mycorrhizal networks are not able to maintain nutrient cycling, soil cohesion, water retention, or plant health.

Example: Agricultural Intensification

Intensive agricultural practices have been a problem for many forest ecosystems for years. Their very existence causes loss of habitat and a vast reduction in local biodiversity. Yet even when mycorrhizal networks are present within these agricultural environments, unsustainable practices can degrade these networks and cause a reduction in mycorrhizal diversity.

Climate Change

We all understand that climate change poses a threat to just about every living thing on the planet Earth, and mycorrhizal networks are not immune. Rising temperatures, altered precipitation patterns, and increased frequency of extreme weather events can disrupt the delicate balance of plant-fungal interactions. At the same time, changes in climate may also shift plant communities, impacting the distribution and composition of associated mycorrhizal fungi.

Pollution

Pollution from pesticides, fertilizers, and industrial waste can cause real harm to mycorrhizal fungi, changing soil chemistry and often eradicating these fungal root systems entirely. If those fungi are attached to nearby plants via symbiosis, they too can be poisoned.

Conservation and Management of Mycorrhizal Networks

It is important that we recognize how critical the role of mycorrhizal networks are in helping to maintain healthy ecosystems. Proper is conservation and land management practices need to be taken into consideration as a means for protecting these unique and vital fungal/plant networks.

Sustainable Land Management

Implementing sustainable land management practices is something that should be discussed in countries all over the world, even though it isn’t. Practices such as crop rotation, reduced tillage, and organic farming methods can help protect mycorrhizal networks. Agroecological approaches that promote diverse cropping and reduced chemical input, prioritize biodiversity and ecosystem health, which then enhance mycorrhizal networks.

Reforestation and Restoration

Forest restoration projects are difficult to manage but are essential for rehabilitating damaged ecosystems and helping mitigate climate change. Some of these programs have already begun incorporating mycorrhizal fungi into their restoration strategies. This has made such strategies highly-successful and has shown to improve plant survival, growth, and ecosystem resilience.

Education and Awareness

It is important that we raising awareness about the importance of mycorrhizal networks by educating people. Sites like True Investigator do their part, but schools, conservation organizations, and government agencies should focus on educating land managers, farmers, and the public about the benefits of mycorrhizal associations.

True Investigator Says…

Today, we learned about the amazing symbiotic relationships that exist between plants and fungi through mycorrhizal networks. These networks, though unseen, are a vital cornerstone of ecosystem health and functionality. These intricate associations enhance nutrient and water uptake, improve soil structure, and facilitate communication among plants, contributing to biodiversity and ecosystem resilience. Unfortunately, like to many ecosystems, these invisible networks are in grave danger thanks to human-created disturbances like climate change, pollution, and deforestation. We must do what we can to protect mycorrhizal networks, to ensure the continued growth of diverse ecosystems for years to come.