rot_collective transcription: Ecological Succession
Note to readers: This post is part of a process of providing text-based and occasionally longer form versions of the posts on rot_collective on instagram. This is to improve accessibility for those using screen readers/TTS and those who prefer to not click through images. As a bonus this also provides a way for us to dynamically update or correct information in posts - that’s really important to us because we don’t want to be leading people towards incorrect information in their landscape practices.
Depending on our energy and time, these posts may be pushed together into a single document for those who want a long read. But our timeframe of publishing these / eventually merging them is totally unknown - we work day jobs and it’s the growing season
Disturbance in the Landscape
An ecological system is composed of growth and disturbance. These naturally form the rhythms that define landscape populations. Succession is a term used to describe how these systems move through different stages of growth and change
When looking at a landscape we may see some older mature growth, adjacent to some recently disturbed ground. This forms a mosaic of ecological states across the landscape.
The term succession was originally used to describe a linear growth from disturbance to ‘old growth’. But ecologists now adopt a more holistic view on succession which includes areas of disturbance in the patchwork of the landscape.
Old growth is not inherently better than another system. What matters is having a full and rich mosaic across our ecosystems.
We can view disturbances (and lack of disturbances) as pressures which transition an area from one ecological community to another, or maintain a holding pattern in the current populations.
For example, consider these relationships:
Beech and Oak trees grow in similar conditions and ranges
Beech trees grow faster than oaks
Beech cannot tolerate fire
Baby oaks can grow in the shade of beeches, but eventually need sun
Oaks can tolerate fire
This means depending on the length of time between fires, beech trees may eventually outcompete oaks, but only until the next fire event when oaks have the opportunity to seize the moment and re-establish their population.
The frequency of fires in the landscape will dictate whether or not beech or oak are dominant in a woodland. Neither tree community is better or worse, they simply reflect the disturbance regimes applied to the land.
After significant disturbance, the land shifts to a state known as 'early successional' which often consists of fast-growing plants with numerous seeds. Early successional is not a good or a bad state. In fact, many of our crops were adapted from early successional plants due to their habit of fast growth and abundant seed.
Some food plants which were adapted from early succesionals include corn (after burning) sunflower (after buffalo grazing) and chickpeas (after landslides and tree fall)
'Weeds' are common in annual gardens due to the continual disturbance which favors early succession crop growth, and also other ‘weedy’ early succession plants.
Disturbance Management
Communities across the globe have always managed landscapes with carefully planned disturbance.
In the Eastern Woodlands, fire was a routinely used disturbance to shift the ecological community towards more productive and stable states through the balancing of grasses, forbs, trees, and shrublands. Traditional farm clearing practices in many areas involved killing trees by ringing the bark, followed by a burn to kill the deadwood and open the land for planting.
Depending on the region, the landscape burned every year, decade, or century.
LANDFIRE is a tool provided by the US Forest Service which provides visualization on numerous aspects of the US ecological communities. Here we can see the ‘fire return interval’ - the average length of time between fires prior to european settlement. The deepest purple colors indicate land burned every 0-5 years, and the deepest green almost never burned (about once a millennia or less). We can see that save for new england and parts of the northern midwest, the east resembled California in the rates of burning.
Milpas are a well-documented meso-american farming tradition that is one of the most productive agricultural systems known. The practice involved burning of woods, followed by selected plantings of food plants until the forest eventually returned, when it was again burned and planted.
For landscape stewards, an overabundance of one ecology and an absence of another indicate a potential to shift disturbances to favor a more rich and balanced landscape system. Part of managing ecology is determining what level of disturbance is desired - ranging from minimal to intense disturbance. This is why landscape-level information and data-driven management is so vital to restoration. You cannot determine an appropriate disturbance regime without knowing what the current landscape state is, and what other ecosystems might be integrated with a shift in disturbance patterns.
Selective disturbance can lead a system to a desired state, and careful plant management can guide it to another. By encouraging plants appropriate to the next stages of succession, a landscape can be gently driven towards a desired ecology.
For example, in a highly disturbed environment like a city, early successional plants are the first community which should appear in a natural setting. If these plants are not already present, they can be introduced to begin reflecting what would be a normal community in this disturbance stage in the ecosystem.
If woodlands are desired as a next stage, disturbance such as fire and mowing can be withheld from grasses to enable woody growth to begin forming. These of course can be selectively planted and invasive plants should continue to be removed despite the withholding of disturbance
Using these Tools
Guiding questions can help stewards seek clarity and refinement in their landscape practices:
What ecological communities were common in my area, but are now missing?
What were the traditional landscape stewardship practices in my area? Who did them, when did they do them, and why?
What is the ecological state I'm driving towards? What are the successional communities between here and there?
Is the seedbank of my soil diverse enough to support disturbance? Or do I need to supplement with transplanting or seed casting?