What is ecological succession? (Video) (2023)

Hello and welcome to this video on ecological succession. Today we are going to talk about what it is, the different types and some examples of each type. Let's begin!

ecological successionsIt is the gradual process by which ecosystems change and evolve over time. Before getting into the subject, let's analyze this concept a little. An ecosystem is a community of living organisms (plants and animals of all kinds) that interact with their inanimate environment (climate, soil, energy flow, etc.). As a community of living and non-living organisms grows and develops, some species may become more prevalent, or other species may invade and depopulate or even eliminate other species. Each species has a set of environmental conditions in which it can most optimally and profusely grow and reproduce. As that dominant species grows, it can change the environment and make it more ideal for another species, in which case the formerly dominant species would begin to decline. Let's look at a quick example to explain this a little better.

Let's say you have an area that's all dirty. After a year or two, you'll see some grass and weeds covering the area, becoming more lush after a few years. Pine seedlings can develop five to fifteen years after an ecosystem's initial cultivation. Pines are sun-loving trees, so they can grow quickly in poor soil and lots of sunlight. In many cases, the pine will be the dominant species in a growing ecosystem for a long time to come; until they are so numerous that their very shadow reduces the amount of sunlight they receive.

After a few decades of pine dominance and growth, we will start to see a developing undergrowth of hardwood trees. Hardwoods can grow in conditions of less exposure to the sun that pines cannot.

Decades or hundreds of years later, the pines eventually die or are severely cut down and replaced with hardwood trees such as oak and walnut, which grow best in partial shade.

In many ecosystems, oak or deciduous forest is often considered the pinnacle. Completion of an ecosystem basically means that it has reached the most stable end product in the succession. Oak or hardwood forest will survive for a long time ecologically. However, there is no culmination of succession if we are talking in geological time, as things are constantly changing.

Speaking of change, let's start to distinguish the different types of succession. I mentioned that the climax oak or hardwood forest will be self-sufficient for a long time. This applies as long as it is not exposed to any external disruptive forces. natural disasters oranthropogenic disasters(artificial) can and likely will occur and will alter the dynamics of ecological succession or wipe out entire ecosystems. Natural environmental events such as wildfires, glacial retreat or volcanic eruptions can decimate large areas and essentially “restart” ecological succession. Some examples of anthropogenic changes that will restart the process could be nuclear explosions, oil spills or the abandonment of man-made structures such as a paved parking lot. Let's look at a quick example about nuclear explosions. The Chernobyl nuclear disaster left behind a barren landscape that remains uninhabitable for humans three decades later. However, radiotrophic fungi that use their own radiation as an energy source have already been found. Disgusting, but very cool.

Let's go back to ecological succession. To distinguish between the two types of ecological succession: primary and secondary, we must look at the environment that existed before the drastic change.

primary successionIt is the formation of a stable ecosystem in a previously uninhabited region. This means that there is no previous soil and no previous living organisms. A really cool example of this is the island of Surtsey, off the south coast of Iceland. This island was formed by an underwater volcanic eruption and surfaced in 1963. As an entirely new island, scientists were eager to study it and see firsthand how primary succession occurs. To avoid contamination of the area, only a few scientists are allowed on the island and it is mostly monitored from the air. Visitors to the island must go through a process to ensure that exotic seeds are not accidentally introduced into the new ecosystem.

What we've seen on Surtsey so far are vascular plants in 1965, moss in 1967, lava lichens in 1970 and the first bush in 1998. As of 2008, 61 distinct species have been identified, of which 30 are currently established on Surtsey Island. 🇧🇷 🇧🇷 Birds were sighted three years after the eruption, and 12 species are regularly found there, including a gull colony since 1984 and puffins since 2004.

So you might be wondering how vascular plants started to populate the island just a few years after its formation. I mean, there's no background, right? At this point, it's just barren, hardened lava rock. Let's talk about pioneer species. Pioneer species are the first species to become established in primary ecological succession. These guys can withstand harsh environmental conditions and perform nitrogen fixation and inorganic carbon fixation. That means they can convert stuff in our atmosphere into a form of energy they can use to grow (some even without sunlight!). Pioneer species such as bacteria, fungi and lichens can accelerate the weathering process. When they die, their organic matter becomes the basis of a thin layer of soil in which grasses and weeds will grow; then bushes and trees; and, finally, trees and larger animals. These tiny bacteria and organisms change the originally uninhabitable environment, making it more suitable for the growth and development of higher species.

Okay, now let's move on to secondary succession.secondary ecological successionis triggered by an event that profoundly disturbs an established ecosystem, usually resulting in the disappearance of most surface vegetation and living organisms; but the soil is still fertile, with enough organic matter to support the resurgence of life. The main difference between primary succession and secondary succession is soil quality. This means; Primary succession may be the only succession that occurs in an ecosystem. When an ecosystem starts on previously discovered terrain and nothing happens to trigger secondary succession, the ecosystem culminates in primary succession. Some examples of secondary succession could be forest fires or deforestation.

Before continuing, I want to give you the definitions of two classifications of ecological succession.autogenous successionOccurs as a result of habitat changes caused by organisms in the ecosystem such as B. shaded by canopy development, eventually leading to the decline of pine species.allogenic successionIt occurs as a result of changes in external physical factors, such as the development of a tree line due to cooler weather as altitude increases.

In case you have no idea what I'm talking about, take a second and see how these trees only grow up to one point on this mountain. The cooler climate high up on the mountain triggers allogenic succession, preventing trees from growing there.

Those examples I gave earlier, forest fires and deforestation, are also examples of allogenic succession. These external changes in the environment will trigger secondary succession. And it's known as secondary succession because this land had vegetation before the outside force disturbed the ecosystem. Secondary succession will then proceed in the same way as primary succession; from grasses to shrubs, seedlings and larger trees; they usually peak in layers of oak or hardwood. Because the soil that remains after the destructive force is still fertile and rich in organic matter, pioneer species don't actually need to colonize first, and secondary succession occurs more quickly than primary succession.

Okay, now that we've covered primary and secondary ecological succession, let's see what you remember.

1. What is an example of a pioneer species?

  1. herb
  2. flowering plants
  3. insects
  4. knitting

The correct answer is D, lichen. Grasses, flowering plants, and insects are examples of higher species that evolve in an ecosystem after pioneer species such as lichens have made it habitable.

2. What is the main difference between primary and secondary ecological succession?

  1. The time it takes to reach the maximum state.
  2. The quality of the floor.
  3. The number of pioneer species.
  4. Secondary Successionforeveroccurs after primary succession.

The correct answer is B, soil quality. Secondary succession is triggered by an event that removes most plants and living organisms from the surface, but leaves the soil fertile with enough organic matter to support the reappearance of life.

Hope this review was helpful! Thanks for watching and happy learning!

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