By Jess Rubin

Before we glimpse into fungi’s ability to co-facilitate alchemy, transforming toxic compounds into benign elements, let us consult with geologic time. According to Western science, mycorrhizae,, the category of fungi this article discusses, appeared 407 million years ago. Fossil evidence in Scotland’s Rhynie chert of an ‘arbuscule*’ (organelle serving as a nutrient exchange center) found inside a plant root, indicates presence of these organisms during the Devonian period. At this time, when plants began to migrate from ocean to land, they needed nutrient and water mining assistance in such thin, embryonic soil. Fungi, who had been colonizing Earth’s rocky substrate for 1-2 hundred million years previously,could readily offer these services. Herein arises, early patterns of ecological economics. In this particular context plants, through their photosynthetic metabolism, share sugars with the fung in or around their roots. Fungi, through their heterotrophic metabolism, provide plants with formerly inaccessible water and nutrients. As unsung ecosystem engineers (in tandem with their microbial symbionts), mycorrhizae span a spectrum from mutually symbiotic to parasitic in their partnerships and survival strategies.
While beyond the scope of this writing, it is worth noting that saprophytic fungi, which degrade substrates such as wood, release enzyme exudates that help break down complex compounds (often toxic, i.e., coal tar, PFAS, etc.) into simpler forms. While complete degradation may require successional strategies of different fungal species and strains and potential plant removal (phytoextraction) for full degradation and remediation, this is possible!
An additional precursor to the topic that must be addressed is the conundrum of outdated nomenclature! Terms applied in the mycological field, such as ‘colonization’, are problematic given their reference to horrific sociological patterns of certain human cultures dominating Original Peoples and their ancestral homelands, thereby disturbing ancient lifeways and networks. Early mycologists may not have considered the implications of such a term for the surrounding socio-ecological community. This terminology needs an upgrade! Call to action to those not in the trenches of scientific research: can someone please propose alternative terms? What more careful words can accurately describe when fungal vegetative bodies grow into or around plant roots? Let’s update these terms!
Balancing two hats of an environmental scientist and ordained priestess in my ancestral tradition, I offer gleanings from six years of work with commercial and endemic mycorrhizal fungi and their botanical counterparts to facilitate ecosystem recovery. While some of this work has been in complex urban sites, this writing focuses solely on agricultural contexts. Out of the seven categories of mycorrhizal fungi, we focus here on arbuscular mycorrhizae. These AMF or endo mycorrhizae, most often found in agriculture and agroforestry ecosystems, partner with most (>85%) deciduous ground cover, herbaceous, shrub, and tree species. While some plant species (i.e., Salix sp) partner with both AMF and ectomycorrhizae (ECM), another category frequently found growing around roots of evergreen trees, oak, hickory, and beach; we remain focused on AMF here.
Wild Nooks are Living Libraries
We were graced to experiment with the role of mycorrhizal banks in crop field edges between plowed fields, wild perennial buffers, and the Winooski River at Diggers’ Mirth Collective Farm at the Intervale in Burlington, VT. While details of the study are readily available on SARE’s website, https://projects.sare.org/project-reports/one21-391/, the gist of what we found was that the wildest parts of the farm had the most active, intact nutrient exchange networks. Go figure!
After conducting all logistics required in sound scientific research: observation, hypothesis, design, installation, maintenance, data gathering, and analysis (sometimes at risk of straining our qualitative relationships with plants & fungi), we discovered what we already knew. More specifically, macronutrient phosphorus (P), which can be a toxin when excessively present in water, had significantly lower concentrations in the wild perennial buffers adjacent to the field than in the tilled/planted field centers. P concentrations increased incrementally, moving inward from wild edges through mycorrhizal banks (we installed)and were highest in field center areas of ripped networks, where, ironically, most of food crops grow. This is shared not to poke farmers but rather as a gentle hugging nudge towards adapting strategies that minimize P inputs, decrease soil disturbance, and nurture underground networks.
Commercial Mycorrhizae Does More Harm Than Good
In our pilot study at Shelburne Farms, we applied commercial mycorrhizae to half of the plots we restored during our early restoration efforts. The soil P, water P, and plant P results between the inoculated and uninoculated restored plots were complex (read about them here). Hence, this new study, branching from the pilot, triples plot numbers for more robust statistics, applies endemic mycorrhizae grown from forest soil on the farm (following the guide we recently published on the SARE Website), includes native riparian plants that host native pollinators, and is designed with polycultures which are 98% edible, medicinal, ceremonial, and artisanal to the Abenaki. While data so far suggests multi-functional forested riparian buffers are the most resilient strategy for watershed protection and trophic regeneration, their inoculation with commercial mycorrhizae is not recommended. One of the leading commercial mycorrhizal blends includes four genera (Rhizopogon, Pisolithus, Suillus, and Laccaria) associated with Pinus sp., which are not present in our plots. Research indicates that applying commercial mycorrhizae in certain ecosystems can complicate underground and corresponding aboveground species assemblages due to mismatches between fungi, native plants and microbial counterparts. In short, when you can, grow endemic mycorrhizae from the wildest, most untouched area of the ecosystem you are restoring!
Applying Endemic Mycorrhizae
There are places where applying mycorrhizal fungi is unnecessary. These places include forests, wild riparian buffers, wetlands, and meadows where endemic mycorrhizae naturally grow and can continue into degraded, debilitated areas nearby. To ensure these ‘living libraries’ can spread their informative influence, these adjacent areas must be protected from tilling, excess P inputs, and plantings that prohibit mycorrhizae (i.e., species in the Brassicaceae family). Plants can obtain P via diffusion when soil concentrations are high in phosphorus. Mycorrhizae may operate more like a parasite in these cases, draining carbon from the plants without necessarily offering nutrient-acquisition. This is one of three theories for why, in our pilot study consistently over four years, the inoculated restored plot hosted less P biomass than the uninoculated plot. In short, mycorrhizae are no silver bullet. Nor do they perform services alone. Rather, they work in tandem with a suite of site-specific microbial symbionts whose synergies depend upon various biotic and abiotic conditions.
It is worth noting that dark septate endophytes (DSE) continue to appear in our root colonization counts. These mysterious fungal-like associates are likely involved in these complex underground networks and merit further study!
Experimenting with Myco-Phytoremediation
As a student of and collaborator with these ambassadors of the underground network, I invite you to consider experimenting with strategies of myco-phytoremediation to facilitate watershed protection through mitigating P runoff into waterbodies. In certain contexts, mycorrhizae can expedite P into plant bodies, which, when harvested selectively (via coppicing and fruit picking) before the plants go senescent (early-mid August), can remove P from the landscape. Back-of-the-envelope calculations quantify how much P can be removed annually via selective harvesting of each species. The P uptaken into the plant body prevents it from re-entering the soil and water. Instead, this selective harvest provides a macronutrient in elderberry syrup, a weft woven into a willow basket, a straight arrowwood shaft, or a medicine gift in braided sweetgrass. While P mitigation, according to scientific literature, takes 6-8 decades to be tangibly evident, if the faucet upstream of P inputs is turned off, this remediation could happen when our children are grandparents if we start now! When the plant palette is edible, medicinal, ceremonial, and artisanal to the Original Peoples who can access their ancestral lands, practicing their lifeways becomes an active form of ecological and social reconciliation. The returning pollinators, informed earth tenders, and activated underground networks unite again after two centuries of disturbance. The trophic webs realign in harmonizing formation.
In summary, we two-leggeds have much to learn from these ecological ancestors in their interspecies collaborations, communication, and networking lifestyles. At the risk of anthropomorphizing processes far beyond our true understanding, I attempted to share glimmers of ancient trails of our research tracks. So much of what occurs cannot be quantified, observed, nor communicated in our mortal modes but certainly can be felt in our innate tending of relationships, ecosystems, and watershed-oriented communities. Glimpses of our ancestral chords, as a medium of these networks, may be visible in the tree-like arbuscules and hyphae we see in ‘colonized’ plant roots. These imprints remind me of the fragile yet strong threads holding our life force and relationships together. The most honest way to orient to these ecological ancestors is with curiosity, humility, and wonder, knowing they may guide our lives' inner and outer landscapes.
Jess Rubin (she, they, we) founded & facilitates ecological resilience service MycoEvolve (www.mycoelvolve.net) Burlington, VT, while serving on the VT FSAG (Fungal Scientific Advisory Group), can be reached at yepeth@gmail.com.
Literature Review
2. 2 Years of Research on this Pilot,
3. 4 years of Research on the Pilot, now completed.
This article above is a synopsis of these four peer-reviewed journal articles and guide.(Kolba et al. 2022; Rubin and Görres 2021, 2022a, b; Rubin et al. 2024)
Kolba L, Rubin J, Görres J (2022) Growing Local Mycorrhizal Inoculum, A Guide and Insights from a Field Trial. NESARE, Burlington VT
Rubin J, McGranaghan C, Kolba L, Görres J (2024) Restoring a Degraded Riparian Forested Buffer While Balancing Phosphorus Remediation, Biodiversity, and Indigenous Land Access. Sustainability 16:3366. https://doi.org/10.3390/su16083366
Rubin JA, Görres JH (2021) Potential for Mycorrhizae-Assisted Phytoremediation of Phosphorus for Improved Water Quality. Int J Environ Res Public Health 18:7. https://doi.org/10.3390/ijerph18010007
Rubin JA, Görres JH (2022a) The effects of mycorrhizae on phosphorus mitigation and pollinator habitat restoration within riparian buffers on unceded land. Restor Ecol 31:e13671. https://doi.org/10.1111/rec.13671
Rubin JA, Görres JH (2022) Effects of mycorrhizae, plants, and soils on phosphorus leaching and plant uptake: Lessons learned from a mesocosm study. PLANTS PEOPLE PLANET 4:403–415. https://doi.org/10.1002/ppp3.10263
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