“Fungi are veteran survivors of ecological disruption. Their ability to cling on—and often flourish—through periods of catastrophic change is one of their defining characteristics. They are inventive, flexible, and collaborative. With much of life on Earth threatened by human activity, are there ways we can partner with fungi to help us adapt? “
– Dr. Merlin Sheldrake – Biologist and Author of Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures (2020)
Fungi can be found everywhere, from urban soils to dense forests. To accept fungi in the landscape is to celebrate birth from life, the impermanence of landscape, and the flux of uncertainty. In a changing climate plagued by an initial surge of unknown futures, decay agents like fungi may thrive in favourable conditions over other organisms, a message that life is adaptive¹. Planting design pedagogy has previously neglected acknowledgement of the value of decomposition, particularly the relationship between fungi and plants. Recent inclusion might be driven by the language pests, pathogens, and decay we have applied in practice, especially from an arboriculture perspective and a fear of the risk and unknown associated with decay, including fungi – for example, in the Routledge Handbook of Urban Forestry, mycorrhizal relationships about urban environments are mentioned once: “Mycorrhizal symbioses are nearly ubiquitous in plants, nevertheless plants growing in urban environments have significantly lower mycorrhizal colonization compared to forested sites because anthropogenic activities strongly depress mycorrhizal fungi².” However, practices can change. This section highlights the hidden relationships between fungi and plants, as well as recent research in the field, featuring insights from landscape architects working in this area.
Mycoheterotrophy
To illustrate a complex relationship between a plant and fungi, we can look to mycoheterotrophy, a still largely unknown process where a plant lacking chlorophyll depends on its relationship with the mycelium of a mycorrhizal fungus for energy, which is typically in a beneficial relationship with a nearby tree host³. These plants, including ghost pipes (Monotropa uniflora) and gnome plant (Hermitomes congestum), to name a few found in the Pacific Northwest, are commonly found in low-light understory habitats and gaining energy by either hacking into mycorrhizal networks, by employing saprotrophic fungi not in a relationship into a mycorrhizal symbiosis, or forming an association with litter and wood-decay fungi, in the case of some myco-heterotrophic orchids³⁴.
Decay and decomposition
Decay is a natural ecosystem process which returns nutrients into soils and improves biodiverse habitat availability for wildlife in the form of standing trees for woodpeckers and course woody debris for microorganisms. In trees, decay can result from diseases, wounds, and fungal establishment within the functional sapwood⁵. Arborists assess individual trees for risk and note decay and dieback in tree canopy, which can result in a hazard and thus warrant removal concerning the level of impact the risk might have on people⁶. Climate change is affecting rates of decomposition in some ecosystems, resulting in the loss of carbon from the land into the atmosphere⁷. At the same time, decomposition can lend to healthy soils which sustain mature trees that can store a large carbon stock. Natural systems are in dynamic equilibriums, neither stable nor in a steady state and entropy plays a large role in sustaining decomposition through new agents of change and pressures (e.g. climate change)⁸. In planting design, it is critical to understand the movement towards entropic decay of a landscape over time, into the creation of something new, a concept that may push beyond aspirations for aesthetic balance across time.
Mycorrhizae
90% of terrestrial plants benefit from mycorrhizal fungal associations¹. Mycorrhizae are fungi in symbiotic relationship with the roots of plants, where the fungus receives carbohydrates from the plant, and the plant receives nutrients from the mycorrhiza in the soil⁹. Evergreen trees and shrubs typically are in a relationship with an ectomycorrhiza as well as deciduous trees including Fagus, Betula, Quercus, Tilia, Populus, Salix, and Castanea, which commonly produce fruiting body mushrooms (basidiomycetes)⁹. The other class, endomycorrhiza directly joins the plant’s roots and is common on deciduous trees and herbaceous plants; they are typically nonspecific to the host⁹. The impact of climate change on temperature, salinity, carbon dioxide levels, and water availability can disrupt processes of mycorrhizae, and in urban areas, they are typically limited in poor soil conditions¹².
Mycoremediation
Mycoremediation is an ecologically regenerative process of using fungi to break down or remove pollutants from an ecosystem using enzymes and acids, typically employed in agricultural practices, industrial clean-ups, and stormwater runoff tools¹⁰. Best practices are to match the strains to the local ecosystem, use cost-effective practices such as straw and wood chip mulch, re-use the substrate as soil compost, and avoid eating the fruiting mushroom bodies¹⁰¹¹. In practice, a recent project by Kate Kennen’s Offshoots and Good Landscape Studio in partnership with the Massachusetts Department of Transportation worked on a 1.5-year research project to explore how stormwater management technology could utilize fungal webs in mitigating water pollutants¹². You can read more about the project here: link.
Climate-adaptive fungi
Recent research suggests arbuscular mycorrhizae, previously thought to be unable to decompose organic matter, may be in relationship with soil organisms in the process of decomposition¹³. Further, ectomycorrhizal fungi are found to help trees absorb carbon dioxide faster, maintaining carbon stock in soils and within trees¹⁴. Fungi are found to be adaptive across biological stages, as seen in the appearance of jelly fungi in their adaptivity towards dry weather through a gelatinous surface and some fungi have been found to thrive on the surface of several different rocks in various climate conditions¹.
Student project examples
Several landscape architecture student projects have explored the topic of decomposition and mycorrhizae, including Karl Bern’s Alternative Methods and Tools for Nature Conservation in which mycelium dowels are grafted onto trees as analogous to play, pause, and stop in the forest (Link). Joyce Fong’s project is centred around the misconception of deadwood as destructive and uses a University park as a staging area to map the ways that people and decomposition can interact (Link).
Listen and learn more about Fungi in landscape architecture
SPORECAST: A Spore-tacular conversation on fungal futures in Landscape Architecture and the climate crisis – 20 minute podcast – listen here
Hosts: Kevin Wong, Kenzie Parry, and Elliot Bellis (UBC MLA + MARCLA students) interviewing Courney Goode (Good Landscape Studio/RISD) and Joseph Dahmen (SALA/Watershed Materials LLC/AFJD Studio).
1. Simões, Marta Filipa. Impact of Climate Change on Fungi. Microbiology Society. Issue: Life on a Changing Planet, 2021.
2. Brunetti, Cecilia. and Fini, Alessio. Fertilization in Urban Landscape. Chapter 29 in Routledge Handbook of Urban Forestry. 1st Edition, 2017.
3. Watkinson, Sarah. Mutualistic Symbiosis Between Fungi and Autotrophs. The Fungi (Third Edition), 2016.
4. Merckx, Vincent, Bidartondo, Martin, and Hynson, Nicole. Myco-heterotrophy: when fungi host plants. Annals of Botany. doi: 10.1093/aob/mcp235, 2009.
5. Boddy, Lynne. Fungal community ecology and wood decomposition processes in Angiosperms: From standing tree to complete decay of coarse woody debris. No. 49, Ecology of Woody Debris in Boreal Forests. pp. 43-56.2001.
6. Raupp, Michael, and Gonthier, Paolo. Biotic Factors – Pests and diseases. Chapter 18 in Routledge Handbook of Urban Forestry. 1st Edition. 2017.
7. Hopkins, Francesca, Torn, Margaret, and Trumbore, Susan. Warming accelerates decomposition of decades-old carbon in forest soils. PNAS Plus. doi: 10.1073/pnas.1120603109. 2012.
8. Treib, Marc. Building Up; Wearing Down Entropy, Erosion, and Expansion. DOI:10.22201/FA.2007252XP.2010.1.26195. 2011.
9. Delahaut, Karen. Mycorrhizae. Wisconsin Master Gardener website and the University of Wisconsin Madison. 2015.
10. American Society of Landscape Architecture. Mycoremediation: Your Landscape on Mushrooms. The Field, 2016.
11. Stamets, Paul. Mycelium Running: How Mushrooms Can Help Save the World. Ten Speed Press, 2005.
12. Kennen, Kate, and Chadderton, Colin. Using mycofiltration treatment for stormwater management. Massachusetts. Dept. of Transportation. 23-035. 2023.
13. Bunn, Rebecca, Simpson, Dylan, Bullington, Lorinda, Lekberk, Ylva, and Janos, David. Revisiting the ‘direct mineral cycling’ hypothesis: arbuscular mycorrhizal fungi colonize leaf litter, but why? The ISME Journal. Vol 13. 1891-1898. 2019.
14. Zak, Donald et al. Exploring the role of ectomycorrhizal fungi in soil carbon dynamics. New Phytologist, 2019.