Walking in a woodland can be an exciting adventure with many plants and animals to see, and as a naturalist, I like to observe and learn about all of the connections between the different species. But, there is a vast network of living organisms under the soil that we cannot see and rarely experience. There are roots of the many plant species around us; some are slim and only a few inches in length, others may be from a few inches to feet in diameter and hundreds of feet long.
Also living underground are species of fungi, vegetative organisms that lack chlorophyll, so they cannot make their own food like green plants growing aboveground. Fungi get their nutrients by sending out thin, tubular root-like filaments called hyphae. When the hyphae come in contact with dead animal matter or plant matter, they release enzymes that break down cellular material that the fungi absorbs as food. Hyphae from one or more fungi can cover large areas with a tangle of threads referred to as a mycelium network. One of the largest is an Armillaria ostoyae fungus in central Oregon that covers close to four square miles.
The interconnecting hyphae and plant roots is called a mycorrhizal web. All of the organisms connected to this web can benefit from it, and many of the organisms are providers to the web, although some only take nourishment and give nothing in return. Green plants use chlorophyll and sunlight to produce sugars and fats, funneling these to all parts of themselves including their root systems. Fungi hyphae are much finer than most plant roots and are able to absorb more water, minerals and other nutrients than most roots. All of these are exchanged through the connections found within a web, to the benefit of all species.
Scientists working in different habitats around the world are discovering more ways in which these networks are being used. Seeds from orchids do not have room for food storage, and rely on this network to obtain carbon necessary for germination. Plants like pinesap, Monotropa hypopitus, do not contain chlorophyll and cannot make their own sugars, a usual source of carbon. They rely on carbon supplied through the network which is used for energy and growth of new cells.
The enzymes released by hyphae and spread throughout the networks function to break down organic matter. Dead organic matter is broken down and recycled as nutrient uptake by the network. This helps to keep the soil healthy in addition to cleaning up decaying matter and providing food for a vast number of plants, animals, and bacteria that inhabit much of the habitat that exists underground. On your next walk, whether in a woodland or your backyard, be aware of the many plant and animal species and individuals and their connections.
To learn more about the following species or topics, click on the name to link to a previous blog:
