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Ecological Succession: Building a Forest in 8 Steps

Ecological Succession: Building a Forest in 8 Steps
A burned forest after about 30 years of succession.

Do you want to build a forest? It will require a lot of ecological succession, or change over time. We'll start with a disaster. Perhaps a fiery tornado has torn through the land and nothing remains, or maybe you want a forest on a lava flow. The first step is to allow primary successors to colonize the land. These are the things that can live on seemingly nothing, think lichen. Then perennials will move in, annuals, small trees, and soon enough you'll have a forest!

During my experience as an ecologist I was lucky enough to see the stages of forest growth, but not everyone has the opportunity to see a forest grown from scratch. Here I have compiled a recipe that you can follow so you too can see your very own forest sprout and grow. Scientists call this process ecological succession.

1. Get yourself a wasteland, or a place that is more or less devoid of life. Perhaps you’ve been lucky enough to inherit a piece of land recently hit by a tornado of fire. Did the land just experience a lava flow?  Most ecologists call these disturbances, although I’m fully aware that this word probably does not do these catastrophic events justice. Don’t worry though, your land may look bad now but in just over 100 years you will have a fully grown climax community, or a forest. It might be difficult to see how anything can survive these events let alone imagine a forest sprouting up, but have no fear, every landscape you see today started as a blank slate of charred ash and rock.

2. Bring in the moss and lichen. Sure they are small but they are powerful. If you’re trying to build a forest on a lava flow, you’re going to need them. They are the pioneers of your landscape and will be important for laying down the first layers of soil.

3. Add in some annual seeds. Although their live-fast-die-young lifestyle won’t keep them going forever, they will lay the groundwork for your forest. As they grow and die quickly and in huge numbers, they add nutrients which will be important for your future forest. Plus, their flowers will look beautiful in the spring and summer.

4. Annual plants are great, but in order to get your forest going you’re going to need perennial shrubs and plants that live more than just a year. At this stage you may also have some actual trees shooting up, but they’ll be small and twiggy.*  *IMPORTANT: If you actually want to build a prairie STOP at this step and set the place on fire every couple of years. 

5. Now we’re cooking up a forest. Next you’ll need to let those trees grow. You might notice that these trees are all the same species, but don’t worry these species grow the best at the beginning. Like the annual plants from step 3, these trees are great first species but they won’t stick around for that long, so enjoy them while they last.


Two forests in different stages of succession. Left is older darker right is almost all aspen
Ecological succession stages: Left forest burned in 1948, right forest burned in 1980.


6. Timber! After some time you’re going to have to let the first trees to colonize your land die. This may be sad, but if you’re not there it might not make a sound, right? Tree falls are important in forests because they allow more slow-growing species to colonize the area. As the forest floor floods with light, these species will take their chance and grow tall and strong. They will increase the diversity of trees, so you won’t just be staring at a matchbox of small saplings.

7. Plant trees that are more slow growing. Oaks are a good examples of these trees. Like everything else, you probably won’t need to do a whole lot of work here. The squirrels and wind will take care of this step. You just need to sit back and watch these old-growth baby trees sprout into 200-year-old behemoths.

8. Now wait...about 50-200 years. Before you know it, you won’t even be able to tell that a pesky asteroid fell in your backyard. You’ll have the diverse old-growth forest of your dreams complete with mature trees.

Really, forests will build themselves, because the world is constantly undergoing change, or succession. This change is made possible because plants are constantly competing with one another for sunlight, water, and nutrients. As disturbance becomes less frequent and plants disperse and grow, forests will begin to grow until you have old towering trees.

Me, Caitlin, trapping invertebrates (insects and other bugs) in forests undergoing ecological succession
Caitlin, trapping invertebrates in a forest burned in the 1910s.
About the Author
Hello, my name is Caitlin Maloney and I am a science and conservation communications intern here at The Morton Arboretum. I have been working on a variety of projects including developing presentations, helping the Chicago Region Tree Initiative, and working and planning events for visitors. As an undergraduate I earned a B.S. in biology and English from Hobart and William Smith Colleges. I then went on to get a master's degree in biology studying soil invertebrates at Bowling Green State University. What I really enjoy, though, is communicating science through writing and speaking. I co-produce and host a podcast called Bugs&Stuff, and I love sharing my excitement about science with anyone who will listen because everyone deserves to know a little more about the place we live.