Soil Succession: From Barren Soil to a Thriving Forest Ecosystem

Permaculture Practices & Soil Health
Written By Kevin Wallace

Soil succession is the quiet work underfoot that turns bare ground into something that can hold a garden, a hedge, or a forest. It is one of the more useful mental models we lean on here at the Sanctuary, because it explains why a vegetable bed, a lawn, and a food forest all genuinely want different soil.

You can picture it as a long conversation between plants and the life that eats what they drop. Early on, the conversation is short and fast — simple residues, a lot of bacteria, plants that like disturbance. Later it gets woody and slow — lignin, fungal threads, trees that live on partnerships. Left alone in Central New York, that conversation takes decades to centuries. On a working property you can hurry parts of it, or you can hold a patch back on purpose. The mistake is treating every acre as if it should become a mature forest floor.

Stage 1: Barren soil

Barren ground starts with almost no organic matter. Bare rock, sand, or worn-out dirt. Microbial life is thin because there is little to eat.

The first colonists are the tough ones: lichens, mosses, a few grasses that can stand a hard site. Cyanobacteria and other autotrophic bacteria begin fixing nitrogen and etching minerals out of rock. That is the same process behind the dark, crusty biological soil crust you see on undisturbed bare ground. Do not scrape that crust off just because it looks messy. It is the first skin.

Stage 2: Bacterial-dominated soil

As those pioneers die and rot, they feed bacteria. Bacteria become the main workforce, breaking simple organic matter into nutrients plants can use. Nitrogen-fixers such as Rhizobium and Azotobacter pull nitrogen out of the air. Decomposers such as Bacillus and Pseudomonas chew through the easy residues.

Grasses and herbaceous plants move in. Legumes help, because they partner with nitrogen-fixing bacteria and leave the soil a little richer than they found it. This is early-succession ground: the kind of soil that follows a plow, a flood, or a scrape.

Stage 3: The shift toward fungi

Woody stems change the menu. Leaves and grass clippings are easy food. Branches, bark, and lignin are not. Fungi are built for that slower work.

Mycorrhizal fungi start linking to roots and trading nutrients and water for sugars. The old classroom name was Glomus; modern taxonomy has split much of that group into genera such as Rhizophagus and Funneliformis. Saprophytic fungi such as Trichoderma and Aspergillus work the dead wood and the tougher litter.

Shrubs and perennials show up because the soil is deeper and the partnerships are starting. This is the in-between stage most berry patches and young woody plantings actually live in.

Stage 4: Fungal-dominated forest soil

Give it enough time and enough wood, and the soil becomes a thick, structured medium. Fungi dominate nutrient cycling. Ectomycorrhizal fungi such as Amanita and Boletus partner with trees. Other decomposers, including Penicillium and various Basidiomycetes, keep recycling the litter.

Trees close a canopy. The plant and animal list gets long. That is a mature forest floor. It is not automatically what you want under tomatoes.

Which stage do you actually want?

This is the part that matters on a property instead of in a textbook. You do not have to push every bed to Stage 4.

Annual vegetable beds and lawns generally do best in bacterial-dominated, Stage 2-type soil. Most vegetables and turf grasses are disturbance-adapted, early-succession plants. They evolved for the soil that follows a disruption, not for a fungal forest floor. That is part of why tilling a vegetable bed every year does not wreck it the way tilling a food forest would: you are keeping that soil where the crop actually wants it.

Berries, perennial beds, and young shrubs sit in the Stage 3 zone — still some bacterial activity, but more and more fungal partnership as the planting settles.

Food forests and orchards want to be pushed toward Stage 3 and 4 much faster than bare or recently cleared ground would get there on its own. Trees and woody perennials lean on mycorrhizal partnerships for nutrient and water uptake. If you plant them into a freshly tilled, bacteria-heavy bed and then keep tilling around the trunks, you are asking a forest plant to live in a garden soil.

This bacterial-to-fungal framework is widely taught in permaculture and regenerative-agriculture circles. Dr. Elaine Ingham’s Soil Food Web work is the source most people quote. It is a good directional guide for what to feed a patch and how often to disturb it. Be honest about the numbers, though: the specific fungal-to-bacterial ratios often repeated in workshops have not been rigorously validated as a formula you must hit. Treat them as a compass, not a recipe.

How to speed it up — or hold it back

Nature will do this without you. On a zone 5 homestead you do not have a century to wait, and you also do not have to let every bed run away into woods.

To push soil toward fungi — the move for a new food forest or orchard — use fungal-leaning compost or compost extract. A Johnson-Su bioreactor is built to make that compost. Mulch heavy with woody material such as arborist wood chips. Fungi handle that carbon far better than bacteria do. A hugelkultur bed, with buried logs and branches, is a shortcut toward Stage 3 fungal food. That is part of why it earns its keep under fruit trees and shrubs.

To keep soil bacterial-dominated — the move for a vegetable bed or lawn — use occasional light tillage or cultivation, and compost that has been turned rather than left to sit for a year. That diet and that disturbance keep the balance tilted toward bacteria.

To avoid resetting the work by accident: heavy tillage, compaction, or bare soil left open will knock fungal ground back toward Stage 2. Worth knowing before you till around an established fruit tree or through a patch you have been building toward a food forest.

A next step for this season

Walk the property and name the job of each patch out loud: annual bed, berry row, young trees, or ground you are willing to let go toward woods. Then match the feeding and the disturbance to that job. If a future tree row is still sitting in bare or freshly worked soil, start the fungal side now — wood chips on the surface, no tillage around the planting spots, and a plan for fungal compost when you have it. If a vegetable bed is disappearing under perennial weeds and woody litter, that bed is trying to leave Stage 2. Clear it, cover it, and keep the residues simple.

You do not need to make a forest. You need to stop asking one soil to do three different jobs.

Further Reading

If this model is useful, the next reading should be the manuals and the places, not another list of promises. These are the pieces I would hand a neighbor who wants the biology without the sales pitch.

Local help sits closer than Ithaca: Oswego County Soil and Water Conservation District, 3105 State Route 3, Fulton, NY — https://www.oswegocountysoilandwater.org/ — technical assistance on erosion, cover, and soil conservation for this county.

On Our Website

Succession is the map. These four pieces are the work that actually moves a patch along it, or holds it where the crop wants to stay.

Kevin Wallace
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