I think by "destroy", they meant that the mycelial mat that connects the whole organism is broken up when you dig up the soil. It weakens whatever's there and it could be more easily killed by other species of fungi or bacteria. If it's a fungus that helps plants collect water, then the water-collecting capacity will take a hit until everything's connected up again. I don't think digging up a few spots will kill the whole thing.
well said.
AM (Arbuscular Mycorrhizal Fungi) need roots to grow.
you can not increase them in the soil without live growing plants.
they can lay dormant for months, maybe years,
but their numbers will rapidly start to decrease
without living roots
they form a network, not just off of the roots of 1 plant
but, actually between plants, sharing minerals and water.
digging a small hole will temporarily disturb them, and lower their numbers
but they will come back if conditions are right.
in big Agriculture, where a disc is used several times a year to disturb (TILL) the soil
the numbers never get to rebound properly.
especially when chemical fertilizers are added
if tilled over and over again for years, it can kill off some species
(or, more likely, the numbers are just so low it would take decades for them to rebound)
Keep in mind, there are usually several types of AM Fungi that can be helpful for any 1 species of plant.
some of them do better (multiply faster) at a certain temp, some at a certain moisture level etc...
so, its good to have a large diverse set of them
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Vesicular-arbuscular mycorrhiza (VAM) is formed by the symbiotic association between certain phycomycetous fungi and angiosperm roots. The fungus colonizes the root cortex forming a mycelial network and characteristic vesicles (bladder-like structures) and arbuscules (branched finger-like hyphae).
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An arbuscular mycorrhizal fungus
(plural mycorrhizae or mycorrhizas, a.k.a. endomycorrhiza, AM fungi, or AMF)
is a type of mycorrhiza in which the fungus penetrates the cortical cells of the roots of a vascular plant.
Endo Vs Ecto
Endomycorrhizae have an exchange mechanism on the inside of the root (and the hyphae extend outside the root). Endomycorrhizal fungi form mostly with green leafy plants and most commercially produced plants. Examples: Most Vegetables, Grasses, Flowers, Shrubs, Fruit Trees, and Ornamentals.
Ectomycorrhizae live only outside of the root. Ectomycorrhizal fungi form mainly with Conifers and Oaks. They are required only for a small percentage of woody type plants/trees.