Mycorrhizal Networks, Plant Interdependence, and the Politics of Naming

Vocabulary flashcards covering the experimental methodology, statistical findings, definitions, and ethical-philosophical naming frameworks related to common mycorrhizal networks (CMNs) based on Lehmann et al. (2025) and Kosoy's lecture on plant interdependence and naming.

Common Mycorrhizal Network (CMN)

A subterranean network formed by at least one mycorrhizal fungal genet simultaneously colonizing or interacting with the roots of two or more individual plants, irrespective of connection type.

Common Mycorrhizal Network with Hyphal Continuity (CMN-HC)

A specific common mycorrhizal network characterized by direct, unbroken hyphal connections between plant roots, enabling continuous cytoplasmic flow and direct resource transport while excluding soil-based pathways.

Common Fungal Network (CFN)

A broad conceptual network defined by Rillig et al. (2025) describing interconnections formed among plant roots or hyphae by any fungus, including non-mycorrhizal and filamentous fungi, regardless of connection type.

Network Effect

The net effect induced by linking plants via fungal network formation, encompassing both direct hyphal continuity ($\text{CMN-HC}$) and indirect ($\text{CMN}$) effects; experimentally tested by comparing intact versus mechanically severed hyphal connections.

CMN-HC Effect

The direct effect mediated by a common mycorrhizal network requiring continuous hyphal cytoplasmic flow; tested by maintaining an intact hyphal link while actively suppressing the soil-based pathway using barriers such as air gaps.

Mycorrhiza Effect

The physiological, morphological, and functional changes in host plants caused by the colonization process and maintenance of root colonization; tested experimentally by comparing mycorrhizal plants to non-mycorrhizal control plants.

Root Effect

The ecological consequences induced by the intermingling of roots (e.g., direct root-to-root competition or facilitation); experimentally tested by comparing open passage between roots against root-barrier treatments ($\text{mesh} < 50\,\mu\text{m}$ or solid walls).

Soil-Based Pathway

The passive transfer route where materials leached from roots or hyphae (such as exudates or products of senescence) diffuse through the soil matrix between linked rhizospheres and hyphospheres.

Hyphal Pathway

The translocation pathway describing material transfer occurring internally inside or externally on the surface of fungal hyphae between linked rhizospheres and hyphospheres.

Root Pathway

The transport pathway where materials move actively within root tissues (such as nutrients) or passively along the root surface (such as microbes) between linked plant units.

Air Gap

An experimental physical intervention implemented between plant compartments within a growth unit to sever the soil-based diffusion pathway, isolating direct transfer via continuous hyphal cytoplasmic flow ($\text{CMN-HC}$).

Plant Unit vs. Growth Unit

In CMN experimental designs, a plant unit is a single pot compartment housing at least one plant, whereas a growth unit represents the entire experimental setup (pot) containing multiple linked plant units.

Natural Log Response Ratio ($\text{lnRR}$)

The metric of effect size used in meta-analyses, calculated as $\text{lnRR} = \ln(X_t / X_c) = \ln(X_t) - \ln(X_c)$, where $X_t$ is the mean of the treatment group and $X_c$ is the mean of the control group.

Glomeromycotina

The subphylum of fungi comprising all arbuscular mycorrhizal (AM) fungi, which have an almost global distribution and colonize roughly $70\%$ of all vascular plant species.

Arbuscules

Highly branched intraradical fungal structures formed inside host plant root cells by arbuscular mycorrhizal fungi, functioning as the primary plant-fungus resource exchange interface.

Time-Lag Bias

A form of reporting bias characterized by the tendency of scientific studies demonstrating large or highly significant effect sizes to be published earlier than studies demonstrating small, null, or negative effects.

Egger's Regression Test

A statistical test applied in meta-analyses to evaluate funnel plot asymmetry and detect potential publication bias by modeling the relationship between effect sizes and their standard errors.

Findings of Lehmann et al. (2025)

A meta-analysis synthesizing 31 articles (7 evaluating $\text{CMN-HC}$) that revealed CMN effects on plant biomass and tissue nutrients are mostly neutral, small ($\pm 10\%$ at most), and context-dependent, with a negative effect on root-to-shoot ratio and positive effects on root colonization and arbuscule frequency.

Seedling Synthesis Findings (van der Heijden & Horton 2009)

A narrative synthesis of 20 studies (60 cases) assessing CMN-mediated seedling establishment, reporting $48\%$ positive effects, $25\%$ negative effects, $27\%$ no effect, and an overall mean biomass response of approximately $+14\%$.

"Wood-Wide Web" Metaphor

A popular ecological metaphor that describes mycorrhizal networks as cooperative, communicative, and benevolent communal systems, often obscuring evidence of plant competition, exploitation, and context-dependent neutral effects.

Distributive Justice

A paradigm of justice focused predominantly on measurable, quantitative distributions and outcomes (such as resource flows, speed, and amounts), identified by Karen Houle as dominating ecological and social frameworks.

Conceptual Monoculture

Karen Houle's concept denoting the intellectual condition where a single dominant framing (specifically distributive justice) crowds out alternative modes of ethical evaluation, such as procedural, virtue, and linguistic justice.

Performative Naming

A philosophical concept derived from J.L. Austin and expanded by Karen Houle, asserting that naming is an action that actively constructs worlds and calls forth specific relations rather than merely passively describing reality.

Enframing (Gestell)

Martin Heidegger's term for a technological mode of revealing that structures the world and living beings purely as resources ordered and calculated for utility and extraction.

Standing Reserve (Bestand)

The ontological state resulting from enframing, wherein nature is rendered merely as calculable, fungible, and extractable raw material rather than as entities with inherent relational value.

Linguistic Responsibility

The ethical and scientific obligation to remain accountable for what specific vocabularies reveal, privilege, or suppress when describing ecological phenomena.

Linguistic Justice

A non-distributive form of justice described by Karen Houle that evaluates word use and framing itself as an inherently ethical and political act capable of including or erasing distinct ecological realities.

The Double Naming of Douglas Fir

Karen Houle's case study contrasting the epidemiological naming of Douglas fir as a "Carrier" (a disease vector for Cryptococcus gattii) with an Indigenous Carrier language inscription on a culturally modified tree, illustrating how naming either reduces an organism to a threat or reveals historical relationality.