Dr. Tim Sandle
July 7, 2026
Digital Journal
Evergreen conifers are less able to survive in drought conditions than other heartier trees that line the landscapes. Source – US Geological Survey
Forests are often described in terms of individual trees, timber volume, carbon storage, or biodiversity. Yet one of the most influential developments in forest ecology over the past three decades has been the recognition that trees are not merely isolated competitors for light, water and nutrients. They are also connected through underground fungal networks that can move resources and information through forest ecosystems.
Much of this shift in thinking is associated with the work of Canadian forest ecologist Suzanne Simard, Professor of Forest Ecology at the University of British Columbia and leader of the Mother Tree Project.
Simard’s internationally recognised research helped establish that trees can be linked below ground through common mycorrhizal networks — fungal threads associated with roots. Her landmark 1997 Nature paper, “Net transfer of carbon between ectomycorrhizal tree species in the field,” demonstrated carbon transfer between paper birch and Douglas-fir connected by shared ectomycorrhizal fungi.
The idea has since become widely known as the “wood-wide web”, a phrase that captures the sense of forests as connected systems. While the metaphor has sometimes outrun the science, the underlying research has opened up serious questions about how forests regenerate, how seedlings survive, how carbon moves below ground, and how forestry practices might need to change in response to climate stress.
Forests are often described in terms of individual trees, timber volume, carbon storage, or biodiversity. Yet one of the most influential developments in forest ecology over the past three decades has been the recognition that trees are not merely isolated competitors for light, water and nutrients. They are also connected through underground fungal networks that can move resources and information through forest ecosystems.
Much of this shift in thinking is associated with the work of Canadian forest ecologist Suzanne Simard, Professor of Forest Ecology at the University of British Columbia and leader of the Mother Tree Project.
Simard’s internationally recognised research helped establish that trees can be linked below ground through common mycorrhizal networks — fungal threads associated with roots. Her landmark 1997 Nature paper, “Net transfer of carbon between ectomycorrhizal tree species in the field,” demonstrated carbon transfer between paper birch and Douglas-fir connected by shared ectomycorrhizal fungi.
The idea has since become widely known as the “wood-wide web”, a phrase that captures the sense of forests as connected systems. While the metaphor has sometimes outrun the science, the underlying research has opened up serious questions about how forests regenerate, how seedlings survive, how carbon moves below ground, and how forestry practices might need to change in response to climate stress.
From competition to connection
Traditional forestry models often placed heavy emphasis on competition: trees competing for sunlight, water and soil nutrients. This view underpinned management practices such as clear-cutting, replanting and removal of competing vegetation. Simard’s research challenged this simplification by showing that mixed-species forests may involve resource exchange as well as competition.
Her work indicated that carbon can move between tree species through fungal networks, with seasonal and ecological context appearing to matter. For example, paper birch and Douglas-fir may exchange carbon under different light conditions and stages of growth. Such findings suggest that neighbouring species may function less as simple rivals and more as participants in a complex adaptive system.
This does not mean that forests operate as harmonious wholes or that every tree altruistically supports every other tree. Rather, the science points to a more nuanced ecological reality. Competition, facilitation, kinship effects, nutrient exchange and fungal mediation may all occur simultaneously, depending on species, fungal partners, climate, soil type and disturbance history.
The importance of “mother trees”
One of Simard’s most influential ideas is that large, older trees can act as highly connected hubs within mycorrhizal networks. These “mother trees” may play an important role in supporting forest regeneration by linking seedlings into existing fungal networks and contributing to below-ground resource flows.
The Mother Tree Project, established in 2015, investigates how retaining large trees and protecting below-ground connections can influence forest recovery after harvesting and disturbance. The project examines different levels of tree retention across climatic gradients in British Columbia, with attention to seedling survival, forest resilience and climate adaptation. This matters because forestry is entering a period of heightened uncertainty. Wildfire, drought, insect outbreaks and climate-driven stress are altering regeneration patterns across many regions. If old trees and fungal networks improve seedling establishment, then forest management focused solely on above-ground timber yield may miss key drivers of long-term ecosystem recovery.
Canadian science with global reach
Simard’s work has had particular resonance because it emerged from Canada’s forest landscapes, especially British Columbia’s mixed forests. Canada holds vast forest resources, and decisions about harvesting, replanting and conservation carry consequences for ecosystems, rural economies, Indigenous stewardship, biodiversity and carbon accounting.
Her research has also become globally influential because it speaks to a broader rethinking of ecology. Forests are increasingly understood as dynamic networks involving trees, fungi, bacteria, wildlife, soil chemistry, hydrology and climate feedbacks. This systems view is relevant not only to Canadian forestry but also to restoration projects in Europe, tropical reforestation, agroforestry and carbon-market planning.
At the same time, the field remains scientifically active and sometimes contested. Some researchers have questioned how far evidence for common mycorrhizal networks should be generalised, especially when popular accounts imply intentional tree communication. Simard and colleagues responded in 2025 that decades of peer-reviewed research support the existence and ecological relevance of common mycorrhizal networks, while acknowledging the need for careful interpretation and further study.
One reason the science is economically important is carbon. Forest carbon accounting has traditionally focused heavily on trunks, branches, leaves and soils. Yet mycorrhizal fungi are central to moving plant-derived carbon below ground and shaping whether this carbon is stored, respired or stabilised in soil. Recent ecological research suggests that mycorrhizal associations influence both above-ground biomass carbon and soil carbon dynamics. Different fungal partnerships, such as ectomycorrhizal and arbuscular mycorrhizal associations, appear to support different carbon and nutrient pathways.
This has practical implications for carbon markets and climate policy. If forest restoration or harvesting strategies damage fungal networks, they may reduce long-term carbon storage or impair regeneration. Conversely, practices that retain older trees, protect soil structure, maintain species diversity and support fungal health could improve carbon outcomes. For Canada, this links directly to economic opportunity. Better understanding of mycorrhizal systems could support more credible forest-carbon projects, improved restoration protocols, climate-resilient forestry and innovation in soil-carbon monitoring.
The first opportunity lies in regenerative forestry. Instead of treating forests as timber inventories, management can be designed around maintaining ecological function. Retention forestry, mixed-species planting, protection of old-growth remnants and reduced soil disturbance may all help preserve the biological infrastructure that supports forest recovery.
The second opportunity concerns forest restoration services. As governments and companies invest in restoring degraded landscapes, there is growing demand for evidence-based methods that improve seedling survival and ecosystem resilience. Simard’s work suggests that successful restoration may require attention not only to which tree species are planted but also to the existing fungal networks and legacy trees that help new growth establish.
The third opportunity is carbon finance. Carbon offset schemes increasingly need stronger evidence that claimed carbon gains are durable and ecologically credible. Incorporating fungal network health, soil-carbon dynamics and forest resilience into project design could improve the credibility of forest-based carbon programmes.
The fourth opportunity is agriculture and agroforestry. Although Simard’s best-known work concerns forest trees, mycorrhizal fungi also matter in farming systems. There is growing interest in practices that protect soil fungi, reduce excessive disturbance and improve nutrient cycling. Canadian agricultural discussions increasingly connect fungal networks with soil health and carbon management.
The next stage of development will depend heavily on measurement. Forest managers and investors need tools that can assess fungal diversity, soil carbon, root connectivity, seedling establishment and ecosystem resilience. Advances in DNA sequencing, isotopic tracing, remote sensing, machine learning and soil analytics could turn previously invisible fungal processes into measurable management indicators. This creates space for Canadian innovation. A country with major forestry, agriculture and climate-technology sectors is well positioned to develop practical tools for below-ground ecosystem assessment. The business opportunity is not simply selling trees or carbon credits; it is building the scientific infrastructure for resilient land stewardship.
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