Half of biodiversity in forests lives belowground. These organisms are tiny but their importance to the ecosystem is enormous. In one teaspoon of forest soil there are thousands of species and billions of individual organisms.
A cubic centitmetre of forest soil can contain more than a kilometre of fungal hyphae.
This fascinating diversity of belowground life is arranged into complex food webs. This complex network has been mostly ignored in forest management, but could be the key to making our forests resilient to stresses imposed by global climate change.
All life belowground depends on plants for nourishment. Some soil organisms feed on dead leaves and roots which they turn into soil organic matter. This is essential for soil fertility and water retention, and is the primary reservoir for soil carbon.
Harvesting trees breaks the critical flow of resources belowground, directly reducing the abundance and diversity of soil life. However, harvesting practices that keep living trees within 15 metres of each other, can maintain soil life throughout the harvested area.
Forest harvesting practices that retain a portion of the living trees, such as continuous cover forestry and retention forestry can help keep the soil alive in harevested areas.
Plant diversity also matters, as species differ in the variety of compounds released by their roots which affects microbial diversity in the soil. Soil diversity can be encouraged by establishing forests with more than one tree species.
Soil organisms represent half of the biodiversity of forests and regulate the processes that govern soil fertility, water retention and greenhouse gas emissions. Forestry techniques that foster soil biodiversity can assist in making our forest resilient and diverse.
The crucial role of inputs from living roots for sustaining organic matter and belowground life has been recognized in agriculture and is a central principle of regenerative agriculture, a suite of practices that actively restore soil quality, biodiversity, ecosystem health and water quality while producing sufficient food of high quality nutrition.
Forestry can be regenerative, particularly if we apply practices such as continuous cover and species mixtures and intentionally conserve life belowground.