Succession and Climate Change
With my vague conceptual understanding of succession, I have a few thoughts. Succession is the development of a community (unit of vegetation) after disturbance. So imagine a recently erupted volcano- it wiped out everything, so there is no life to begin with. Then as time goes on, more and more plants can live in the space. At first it’s only a few plants with high disturbance-toleration, but over time as nitrogen and other resources are built up eventually you can have a diverse forest.
Succession is an important part of diversity and natural cycles- consider the Jack Pine cone, which needs fire to open and disperse its seeds. I believe that restraining natural succession is a dangerous practice that could result in less biodiversity.
Pine Beetles in the Rocky Mountain National Park have an easy time moving from lodgepole pine to lodgepole pine and killing the trees because the trees are so close together- Could this easy access be a result of humans overly protecting the forest and not allowing natural disturbance such as forest fires? At this point, with the wide spread of pine beetles, the only thing that the park service can do is spray a few trees in high traffic areas (spraying is very affective, but it only lasts for a year due to the beetle life cycle, and it’s expensive), hope for a very cold winter (a certain number of very cold days in a row would greatly diminish the pine beetle population), and hope that a fire doesn’t start nearby because there would be a lot of really dry timber all piled on tope of itself. Or maybe a large fire would kill off the beetles? But such a large fire would be sure to affect a lot of people and other life as well. This is all fairly speculative; I am constantly striving to learn more about pine beetles and the blue-stain fungus that they carry.
So, back to succession, I’m thinking that between climate change, clear-cutting, and other man-made disasters we are creating a lot of disturbance in natural communities. And this disturbance is not so healthy, unlike natural forest fires.
Let’s talk about a hypothetical situation in which most of the world’s natural environments were in the early succession stage due to multiple or a single huge disturbance event. Would plants that usually come later in succession, such as larger trees like Hemlocks and Spruce, be practically extinct? If there are few to no older ones left to reproduce, how can the area progress to that stage?
I have a picture in my mind of millions of interwoven communities around the world all in different stages of succession. (I prefer a more cyclic image of succession, suggesting continual change rather than a climactic one, suggesting an endpoint or goal) So they’re all going through this cycle as the species, vegetation, and abiotic factors of the environment changes. But there aren’t so distinct lines and boundaries between the communities because when a community is ready to house trees, it gets trees. Where do the seeds for the trees come from, other than a community nearby at a slightly different stage of succession? So if there aren’t any communities at a different stages, and all of them must start anew, where will they get the seeds for the next step?
I suppose this is an obvious conclusion. It’s like the meteor shower wiping out the dinosaurs. A lot of life had to start over again and evolve into something new. Only some species survived. It was a makeover for the planet.
We have a delicate system, and adjustment takes a long time. The systems of the planet manage to adjust to change amazingly well, but for organisms such as ourselves, with our slow reproduction rate, evolution takes millions of years. Growth after disturbance takes a while, especially if all the stages need to re-evolve.