Fungi help gardens flourish

By Alison Pouliot

With their earthy fragrances and myriad colours, fungi capture the essence of autumn. Often better known for their edible varieties that enhance our seasonal cuisine, fungi underpin the health of almost every terrestrial ecosystem on the planet.

We are often only aware of fungi when mushrooms push through the earth, but the growing and feeding part of the fungus exists underground as a network of connective fibres known as mycelia. This scaffold of mycelia provides the basic architecture of soil, underpinning the foundation and function of above-ground life.

Many fungi also form connections with a huge variety of plants in a process called mycorrhizal symbioses. In these subterranean alliances, fungi greatly extend plant root systems, helping them to access water and nutrients. Fungi also improve the resilience and health of plants by increasing their drought tolerance and resistance to soil-borne disease.

In return for this work, plants supply fungi with sugars produced through photosynthesis. These symbiotic relationships are especially important in old and weathered, phosphorus-poor soils found throughout Australia.

We also know that mycorrhizal networks stretch beyond just individual trees. Fungi extend relationships through the soil to other plants, facilitating nutrient transfer between them and uniting plant communities. Mycorrhizal networks orchestrate plant interactions, promoting their growth and survival.

Fungi are the prime recyclers of organic matter, returning nutrients to the soil and making them available to plants. They do this by secreting enzymes that can degrade almost any organic material containing carbon. Bacteria and invertebrates also contribute to decomposition processes, but only fungi degrade lignin – one of the compounds that gives wood its hardness and structure. Every leaf and stick that falls to the ground is likely to be recycled by fungi. The healthiest gardens are those that harbour the greatest diversity of fungi.

Gardeners can encourage fungi in their gardens by retaining organic matter (leaves, sticks, branches, bark etc.) in a range of ages, sizes, and species. This provides the best opportunity for a diversity of microhabitats and microclimates that allow fungi to colonise. Minimising stresses to fungi through physical disturbance to soils such as digging, compaction, over-watering, excessive use of fire, fertilisers or chemicals will allow fungi to reach their full potential in supporting your garden.

Dr Alison Pouliot is an ecologist and photographer who runs fungal ecology workshops in Australia and internationally. She is author of The Allure of Fungi, Wild Mushrooming and Underground Lovers. www.alisonpouliot.com.