Invasive plants versus mycorrhizae fungi

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By Ethan Proud | PREVIEW Columnist

Fungi are a fascinating kingdom of life and can be found in many different aspects of the natural world, connecting ecosystems and forming symbiotic associations with nearly all lifeforms. Fungi are even present in our digestive system, helping us to gain nutrients from the foods we eat. 

In the great outdoors, a similar function is performed by mycorrhizal fungi, which form an association with the roots of plants. This is a beneficial association that helps plants take up more nutrients or share nutrients between different plants, sometimes of different species. Some plant species like spotted coralroot and pinedrops are parasitic plants that tap into this network to steal nutrients and thus do not produce chlorophyll to photosensitize and lack a green coloration.

Invasive plants can negatively impact this network in a variety of ways and can have lasting impacts on soil health once the invader is removed. Some changes can even be permanent if the invader causes the extinction of a native plant species. Invasive species can disrupt fungal and plant associations in two major ways: change in available host plants for fungus through competition and displacement, and production of compounds that are toxic to mycorrhizal fungi.

In the first scenario, the displacement of native species affects the quality and quantity of plant partners for the fungi. This disruption of the plant biodiversity has negative impacts on the soil biodiversity. The longer the invasive species is present, the fungi population is reduced and the soil may no longer be able to host the species that were there pre-invasion.

In the second scenario, the invader secretes a chemical from its root system that kills either other plants or mycorrhizal fungi. Invasions of certain mustard species can reduce fungi colonization on tree roots and affect seedling recruitment and growth. The term for plants that secrete chemicals to damage other plants and fungi is allelopathy. Allelopathic chemicals can be broken down in some cases by soil microbes and, in other cases, the chemicals may persist long after the invader has been successfully removed, leading to a shift in fungal richness and the plant species supported.

Invasive plant management is species conservation and protects our native biodiversity. There is a misconception that all weeds are soil colonizers and play an important role in our ecosystems. Not all introduced species have negative impacts to our ecosystems, but the ones that do make lasting changes that can forever alter our landscapes.

The information for this article was pulled from “Mycorrhizae, invasions, and the temporal dynamics of mutualism disruption” by Sara Grove, Karen Haubensak, Catherine Gehring and Ingrid Parker.

Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.

Upcoming events

April 28 — An evening discussion on climate and weather at 6 p.m. at the Extension office.

May 6 — Weed Warrior Program presentations from 9 a.m. to noon at the Extension building. The Weed Warrior Program will cover an introduction to noxious weeds, their control and how to be a steward in your community. Please RSVP with Ethan Proud at eproud@archuletacounty.org.

May 10 and 11 — Certified seed potato will be on sale for $2 per pound. This year we will not be taking orders; it is a first-come, first-served service. Please bring your own bag or box to take your seed home. 

May 19 — Archuleta County Fair Board Dance, 5 to 9 p.m. at the Extension Exhibit Hall.

CPR and first aid classes

CPR and first aid certification classes are offered monthly by the CSU Extension office, generally on the second Monday and Wednesday of each month from 6 to 10 p.m. The cost for the classes is $80 for combined CPR/first aid and $55 for CPR, first aid or recertification. Call the Extension office at (970) 246-5931 to register.