Thinking Like a Forest
The key to a successful permanent agriculture is to understand stable ecological systems well enough that you can imitate one, or at least key elements of one, on your site. If you can replicate those elements, you can create your own system that is mostly self-sustaining, and dripping with food and other useful yields.
In the soils section, we’ve explored some of the elements of how soil is built in a permanent system. Let’s take a look at the role that plants play, and how they cooperate with each other and other aspects of nature to build a robust, super productive and resilient system.
How does nature transform a degraded, empty piece of earth to a beautiful mature forest system?
Succession in Nature
Nature has developed stages, and different plants at different stages hold key roles that help the system to mature and become more robust and complex over time. This is called “Succession.”
A system starts with simple life forms like lichens and mosses, and then moves to annual grasses and weeds that can grow in harsh environments (drought, heat, wind exposure, low nutrition).
These are called “pioneer weeds” because they are able to grow on barren, degraded or damaged land. These open the soil with their roots, and die back and provide further organic matter to the system. They also provide enough shade and wind protection to hold moisture so that small bushes can get a foothold.
As those small bushes grow, they in turn provide shelter and organic material for small trees, which provide shelter for larger trees until a climate forest system is created.
A secondary succession is where a mature system has been destroyed whether through fire or clear cut, plowing, etc. This tends to start with pioneer weeds and goes from there. Note that these two examples are one example of succession, a temperate forest.
There are many forms of succession that are somewhat different from each other but have similarities, such as desert, dune, estuary, perennial prairie/savanna, and fire ecology, which has adapted to burning naturally and regularly.
Let’s look at some examples of a forest succession process.
Pioneer stage The above photo is a ranch at Pine Ridge reservation that has been overgrazed. Only very tough grasses will grow, except in the ravines where there is more moisture and shelter from the wind.
The soil has been compacted, pasture diversity is reduced as grasses have been grazed too low and all but the toughest have been killed off (buffalo grass here, mainly). The main plants that grow here are the toughest of wildflowers, like thistles.
This is a degraded prairie system mixed with pine (some of the original elements have survived).
Pioneer weeds can handle severe drought, severe temperature extremes, baking sun, compacted soil, nutrient poor systems, predators, and other pressure.
They are annual plants, meaning they sprout from seed and die in one season, they grow rapidly, they usually produce many seeds that are designed to be dispersed (think of a dandelion or thistle), sometimes they produce more than one generation per season. They are built to find the small niches in a hostile climate that they can survive in, and spread to find other niches.
This is a plowed field which is a similar system, with compacted soil, destroyed friendly biology, roots killed, etc. This field is prime for the only thing that is programmed to grow there - the toughest weeds around. They tend to overpower everything - nature sent them to heal the system but to us, because we don’t understand their function, they are an “enemy”.
When this field is plowed every year, it is returned to the “pioneer” stage and only the tough weeds can grow there without assistance. When you till your garden, you’re creating a perfect home for the toughest weeds around.
Such a system needs constant maintenance because you’re creating the exact conditions that only “weeds” can grow in without help. This is a banana field, filled with tough plants like thistles that rob nutrients from the bananas instead of feeding them which a permaculture system will do.
“Devil’s weed”, “puncture vine” or “Goathead” (because of the two spikes coming out of the seeds, like goat horns - that can puncture a bike tire or your tennis shoe), is a typical plant that thrives in disturbed soils and will quickly cover an entire area of unprotected soils.
The seeds stick to animals (and you) and spread to new areas. The plant sprawls in all directions and covers the ground quickly. We had fun with this one in our new garden beds at Pine Ridge reservation. When harvested, these pioneer weeds make great compost. They usually are able to access minerals other plants struggle to access from degraded soil.
A plowed field is not unlike an abandoned parking lot. Here you can see just how tough these pioneer plants are - they can grow in any crack and actually widen the cracks while building soil with their deaths, creating the conditions for the next stage of succession.
Stage 2 succession This stage includes a wider variety of perennial grasses and wildflowers, and perhaps some small woody plants as well. Grasses dominate this system whereas the toughest wildflower weeds dominate a pioneer system. (In the background, you see stage 3 succession, small trees.)
The pioneer weeds have opened up compacted soil, they have contributed their biomass when they die, adding fertility to the soil, they offer shade protection and help hold moisture in the soil. The next stage of plants is able to survive because of the added protection pioneer plants provided.
Remember this next time you run out to weed your garden bed. It’s better off with the protection of your weed cover than allowed to dry out, with compost being blown away in the wind or washed away in rains.
The soil is opening up, there is more organic matter, more diversity, plants are taller and create more wind protection, and the soil is able to hold more water and air as root systems become more complex and thicken. These plants start shading out the pioneer weeds.
Stage 2 succession in this parking lot shows a wider variety of weeds, including more delicate wildflowers, not just the toughest pioneer types. These continue to add organic matter and break up the concrete.
Stage 3 succession Note the established perennial grasses, flowers, bushes and small trees. This is a healthy ecosystem that is becoming more stable. It’s harder to degrade - you’d have to clear cut the trees and compact the soil.
The first trees in a system will be the toughest pioneer trees. They don’t need the protection of other trees. They can compete with grasses (many trees struggle with that). They can handle wind, poor soils, drought, and temperature extremes.
There are a few types of trees that can handle this - mostly pine and cedar. They tend to be short and scrubby at this stage.
And yes, nature is powerful and will move through the succession process in a parking lot. This illustrates how powerful this pattern is. These trees and bushes continue to break up degraded soils (in this case, asphalt), deposit more organic material both above the soil and below it (via dead roots).
Grasses are shaded out eventually, and trees become dense enough to provide a protective environment for the final stages of succession. Each stage can take many years. This stage usually takes decades.
This stage ends with pioneer trees fully grown and covering most of the area, shading out grasses in a bed of nutritious soil built over many years from needle drop and tree death.
Stage 4 Pioneer trees have provided enough biomass and protection that now many other types of trees that evolved in the protection of forests can grow. You start getting more diversity of trees, with beech, ash, maple, hickory and other forest trees showing up. The type of tree that shows up is entirely dependent on the ecosystem and on any management mankind has done of the forest.
These get a foothold in a clearing created by the death of one or more mature trees. They compete with each other and other plants for sunlight and nutrition, but by this time, there is much more water and nutrients to go around. These trees will eventually shade out the stage three scrub trees and become a mature “climax” forest ecosystem.
This stage of succession includes some elements of a climax (Stage 5) system, but also has a lot of edge. Lots of clearings, different stages of tree growth, and edge, makes this system the most productive, vibrant and diverse system of any of the stages in many cases.
We are generally striving for this stage when creating a food forest. It is vibrant, very diverse with lots of edge, hyper-productive, and abundant. We can maintain the system in Stage 4 by focusing on fruit trees, preventing mature old growth from dominating the system, chopping and dropping and other permaculture maintenance. Our interaction with the system is minimal to keep the forest going once we are here.
Native Americans used fire, selective harvesting and clearing, and selective planting of fruit trees to maintain Stage 4 succession.
At this point, the parking lot has been mostly overgrown with trees and forest understory plants like vines.
Stage 5 succession, or climax system, would be old growth forests, like redwoods or the boreal forest (subarctic, mostly pine forest) in Canada, or mature jungles. There are always clearings where old trees have fallen, that create little stage 4 areas amidst the old growth, and keep diversity high.
Note the lack of diversity on the forest floor in this example - often there are only a few plants that have adapted to the shady, dense conditions in an old growth forest, and sometimes one type of tree will dominate (redwood, pine, etc), especially in drier climates. You will see much more diversity in the clearings or higher up, growing in the tree branches themselves.
A mature jungle or temperate forest in wetter climates can have a great deal of diversity in it, with many types of trees and thousands of unique plants and creatures within any section of the jungle. This is a very dynamic system.
These tropical systems grow year round and get large amounts of sunlight, nutrients, and water that allow them to evolve at a tremendous rate. Life evolves fast in the tropical jungles and the system is able to support a tremendous abundance of life because of the year around sun, rain, and warmth.
Scientists studying old growth jungles find a completely different set of insects, plants, and animals in each section. The evolutionary pace can be very rapid and the diversity is astounding.
Many indigenous tribes in these forests opened up clearings and planted nutrient dense crops and trees, creating stage 4 food forests amidst the climax systems.
So, why do we want to know this?
Because when we understand how succession works, we can “slam dunk” stage 4 succession by adding in the key elements of the system to our “blank slate” yard. Or we can retain the elements that are already providing some of those services, like a large oak tree for instance.
We recognize the value such a tree has for our system and can integrate it rather than cut it down, which is usually what mainstream fruit tree producers tell you to do.
To the degree we bring those elements into the system, such as rich living soils, and protection from larger trees, we create the conditions for our fruit trees to thrive with fewer inputs from us.
All of these elements should thus be designed into the system and can be “slam dunked.”
If you don’t have mature trees, you can plant fast growing nitrogen fixers or other fast growing trees to provide some quick protection. Some of our favorites include moringa (fast biomass, light shade), enterolobium (nitrogen fixer), and sweet acacia (native nitrogen fixer).
You can build a “forest floor” system with wood chips, logs, leaves and other biomass elements found on forest floors.
You can use native grasses as chop and drop that will also open up the soil. The trick is, what shape is your system in? How degraded is it and what will it take to revert it? If you have heavily compacted clay soils, open your soils first with fodder radish and other tough roots - pioneer species.
Follow each stage of the succession process in a degraded landscape by aggressively correcting what is missing for each section, and you will be able to accelerate the process substantially.
The next sections will go into more detail about how you can rapidly create these thriving systems. These are complex ecosystems with multiple moving parts, but there are only a few simple things you need to know about them to be successful.
Note: Different ecosystemshave different kinds of succession. There are mature prairie grass systems that can capture even more carbon than forests in some cases. There are mosaic systems; a mix of trees and grass. Often these are fire ecologies that either burn regularly naturally, or because indigenous people burned them to keep the canopy open.
Many tribes have subtly or dramatically altered ecosystems with their practices. The systems with stewards who did this with lots of observation and feedback loops and thus kept the ecosystem healthy, diverse and highly abundant, are the ones we find have really valuable lessons to apply to what we’re trying to do.