Succession Confusion

Hi,

I'm relatively new to permaculture and was watching an online lecture by Larry Korn.  He was talking about succession and I have a question.

So, from my understanding ... in early succession the soil tends to be poor/damaged.  In order to amend that we could plant nitrogen fixers and add organic matter (chop and drop, compost).  In the lecture it says to start planting trees and guilds right away to get them growing and to move forward along the path of succession.  

But won't trees and other plants require good soils to grow?  Isn't that why succession happens over time?  

If so, when will we know when the soil is healthy enough to plant later succession plants?  By watching the succession of weeds to herbaceous plants?

Thanks for any clarification,
Tiffany

Hi Tiffany;

Welcome to Permies, and to Permaculture!

My understanding is that permaculture mimics the natural processes, such as succession, but speeds it up. In nature, a piece of land with poor soil will go through succession. First smaller plans will come in, each adding what the soil needs, and these plants act as nurse crops to nurture the small trees that start to grow. Then, as the soil ecology changes, other plants come in and take over, and new trees come in. Here, we have alders, hemlock, fir and cedar. The alders are much more short lived than the others, but act as 'nurse trees' for them, as well as being nitrogen fixers. Once the tree canopy starts to close in, different plants that prefer shade take over from the original plants. And the process goes on.

With permaculture we can speed things up by planting the trees we want along with a variety of nurse crops that will add their goodness to the soil, shelter the young trees, attract beneficial insects, and be used for chop-and-drop. As the trees grow, the plants that we have around and under them will change to work better with more shade. Some of the trees we plant are nurse trees, nitrogen fixers, and chop-and-drop species, and we'll eventually cut man of them down to make room for the productive trees. We want to plant species that will have a good affect on the soil, as well as help the young trees along. We can also use animals to clear an area, scuff up the surface soil, and add their manure. Chickens are the common choice.

So, we have used the natural process, but we have sped it up to get the succession heading in the direct we want at a much faster pace.

I hope this helps!

Cheers
Tracy

Hello!

Succession can happen in a number of different ways depending on the starting point. On one end you have the succession that happened over a long period as the glaciers receded after the last ice age. In this case the plant community slowly changed over a long period of time as soil was built and the climate changed. On the other end you can have the succession that happens after a large tree falls in a forest and creates an opening in the canopy. In this case the plant community changes fairly quickly as the canopy reforms. Then there are examples in between those two ends such as a flood or fire. The starting point determines the rate of succession and the number of steps it goes through.

We have the option to use this knowledge to speed succession up by not waiting for natural recruitment or for early successional species to be replaced on their own. Chop and drop, stacking plants over time and actively managing the stages of succession can make a huge difference in the rate of succession. We also tend to hold our landscapes to an earlier successional stage by causing disturbance in a productive way.

In Daron and my neck of the woods, the natural development of soil following disturbance is often through fast growing nitrogen fixing trees like red alder.

Ecologists talk about primary succession (from rock) and secondary succession (colonization of empty spaces following a disturbance like wind, flood, or fire).  Theories like succession seem to suggest an orderly sequence, are currently replaced in the vegetation ecology literature by more complicated views of vegetation development, like "assembly theory" in which lots of different factors determine who comes, and what happens next.

In a permaculture design, the gardener becomes a source of continuous disturbance and dispersal.  So we are working within an ecological framework, and thinking about disturbance and colonization, but are no longer sitting by and waiting for things to happen.  We bring in abundant nitrogen fixers and tap rooted species, and accelerate the pulsing of growth and decay.

And yes... if you plant a fussy tree on bad soil with no subsidy of any kind, it will suffer.  Sometimes nutrients (manures etc...) are used to replace the services of healthy soil temporarily, until successional dynamics kick in.

I also see compost tea as a form of succession acceleration. You are creating a frenzy of life and succession thereof and applying that to your soil to give it a kickstart. Usually we are looking for fungus in our mature, perennial/forest soils and a compost tea brewed for around 48hrs with good aeration will provide a great start for fungal inoculation of your soils and therefore for your trees. Dr. Elaine Ingham has some great info on this (podcasts, lectures, papers).