Epping Forest is a heavily regulated place. First designated as a royal hunting ground by Henry II in the twelfth century, with severe penalties imposed on commoners for poaching, it has since 1878 been managed by the City of London Corporation, which governs behavior within its bounds using forty-eight bylaws. The forest is today almost completely contained within the M25, the notorious orbital motorway that encircles outer London. Minor roads crisscross it, and it is rarely more than four kilometres wide. Several of its hundred or so lakes and ponds are former blast holes of the V1 “doodlebug” rockets flung at London in 1944. Yet the miraculous fact of Epping’s existence remains: almost six thousand acres of trees, heath, pasture, and waterways, just outside the city limits, its grassland still grazed by the cattle of local commoners, and adders still basking in its glades. Despite its mixed-amenity use—from golf to mountain biking—it retains a greenwood magic.
Earlier this summer I spent two days there, wandering and talking with a young plant scientist named Merlin Sheldrake. Sheldrake is an expert in mycorrhizal fungi, and as such he is part of a research revolution that is changing the way we think about forests. For centuries, fungi were widely held to be harmful to plants, parasites that cause disease and dysfunction. More recently, it has become understood that certain kinds of common fungi exist in subtle symbiosis with plants, bringing about not infection but connection. These fungi send out gossamer-fine fungal tubes called hyphae, which infiltrate the soil and weave into the tips of plant roots at a cellular level. Roots and fungi combine to form what is called a mycorrhiza: itself a growing-together of the Greek words for fungus (mykós) and root (riza). In this way, individual plants are joined to one another by an underground hyphal network: a dazzlingly complex and collaborative structure that has become known as the Wood Wide Web.
The relationship between these mycorrhizal fungi and the plants they connect is now known to be ancient (around four hundred and fifty million years old) and largely one of mutualism—a subset of symbiosis in which both organisms benefit from their association. In the case of the mycorrhizae, the fungi siphon off food from the trees, taking some of the carbon-rich sugar that they produce during photosynthesis. The plants, in turn, obtain nutrients such as phosphorus and nitrogen that the fungi have acquired from the soil, by means of enzymes that the trees do not possess.
The implications of the Wood Wide Web far exceed this basic exchange of goods between plant and fungi, however. The fungal network also allows plants to distribute resources—sugar, nitrogen, and phosphorus—between one another. A dying tree might divest itself of its resources to the benefit of the community, for example, or a young seedling in a heavily shaded understory might be supported with extra resources by its stronger neighbors. Even more remarkably, the network also allows plants to send one another warnings. A plant under attack from aphids can indicate to a nearby plant that it should raise its defensive response before the aphids reach it. It has been known for some time that plants communicate above ground in comparable ways, by means of airborne hormones. But such warnings are more precise in terms of source and recipient when sent by means of the myco-net.
The revelation of the Wood Wide Web’s existence, and the increased understanding of its functions, raises big questions—about where species begin and end; about whether a forest might be better imagined as a single superorganism, rather than a grouping of independent individualistic ones[…]
Continue reading: The Secrets of the Wood Wide Web