#Edible Forest Gardening 101
Emulating Forest Soil Resources
While every forest is different, all of them share a few commonalities in the biomass resources they convert into humus and nutrition. The balance between the inputs is what facilitates the growth of mycelial networks, and the long-term retention of nitrogen.
While building a forest ecosystem using permaculture techniques to accelerate succession (sheet mulching, hugelkultür, bioretention swales), these resources need to be thought of as “inputs,” as in, most of your early work in building a functional forest ecosystem will be in adding the materials your soil needs to support a large quantity of plant and animal life.
Today, I will be covering three of these inputs
The cycling of foliage, whether seasonal or constant, generally builds the sort of soil that the plant dropping the foliage likes, and facilitates co-evolutionary relationships with other organisms. Oak leaves make an acidic soil, and they also take a long time to decompose, due to their having high quantities of lignin. Decomposing oak leaves also provide an ideal environment for a number of fungi, such as these Elfin Saddles (Helvella crispa).
Photo: Mine @ danmarks-natur
Black Walnut foliage contains the allelopathic compound juglone. Plants that can tolerate juglone, like the Paw Paw (Asimina triloba), are found growing under walnuts in the wild: tolerant plants can take full advantage of the nutrition from the decomposing leaves, whereas intolerant plants cannot. [x]
Other plants, like comfrey (Symphytum sp.), are “dynamic accumulators“ (hyperaccumulators): they send down deep roots and accumulate deeply-buried soil nutrition in their foliage, and cycle it to the soil surface layer when their foliage dies. In permaculture, these are often called “fountain plants.”
These are just a few examples. Understanding the relationships between decomposing leaf litter and the ecology of the organisms with which you are working is crucial to designing and building a successful forest ecosystem.
In the garden, you can simulate this system until your plants start sustaining it by using leaf mould and leaf mulches.
I just learned the other day that bees are dependent on mycelium in decomposing wood in order to activate genetic pathways that boost their immunity, and ability to rid themselves of environmental toxins. [x] It’s why you will often see bees clustered around sawdust or a wood chip mulch, or why they often build their hives in tree hollows.
It’s not only bees that benefit from the presence of rotting wood: all sorts of fungi, beneficial bacteria, and insects live in the microcosmic ecosystem of a decomposing log. They comprise a sort of system of biodynamic innoculants, which improves the health of nearby organisms.
Using wood at the soil level is also a form of long-term carbon sequestration.
In the garden, you can simulate this system by using wood chip mulches and ‘chop and drop’ mulches with tree prunings. For the sake of accessibility, pruning and mulching are rather constant aspects of forest garden maintenance, rather than just initial inputs.
3. Animal Waste and Remains
Walking around in the local forest today—now that almost everything is brown and crunchy—I was struck by the sheer number of white splashes of guano spread across the forest floor. When the birds move in, so does their waste, which improves the soil over time, providing trace nutrients like calcium, sulfur, and magnesium, as well as your regular NPK (nitrogen - phosphorus - potassium). Guano is also a nematicide, and a compost activator: seeding digestive microorganisms into the ecosystem.
Additionally, there isn’t a single walk that goes by where I don’t encounter something like this out in the forest:
Photo: Mine @ danmarks-natur; more swan remains
It’s been found that the actions of predators return vital nutrients to the soil. For example, numerous studies have shown that bears, in their extraction of salmon from the waterways, return phosphorus to the soil (fish bones are high in phosphorus), and alter patterns of nitrogen cycling along riparian ecosystems. [x] Therefore, animal bones, blood, and tissues are also key components of a healthy forest biome.
When I use seaweed mulches, I also bring in the remains of thousands of little sea creatures, which provide a broad spectrum of nutrition to my soil.
In the garden, you can simulate this system until your local wildlife moves in and starts sustaining it by using compost inputs like eggshells, bone and blood meal, and urine.
If you are building a forest garden, I’d encourage you to take time to observe these natural processes. Most of the time I get my best ideas about how to grow things through careful observation of my environment, followed by a whole lot of reading and asking questions!
Related: What’s in a mulch?
#bioregionalism #soil science #ecology #agroforestry
