In Costa Rica, large tracts of rainforest have been cut down and burned to make grazing pastures for cattle. In some areas, the land has been reclaimed for pres

Question

 

Apply information to scientifically explain what type of ecological succession has happened, why?

Answer 1

Ecological Succession is the slow process of changes that occur after a disaster or when new land is formed. This can take a very long time, but eventually will lead to what is known as a climax community, which is stable and tends to represent the standard ecosystems/ biomes as we know them.

There are two types of succession, primary and secondary. The major difference between them is the presence of soil after the disturbance occurs.

Primary succession occurs when there is no previous soil formation (or at least no access to it). There are two common occurrences: 1)Volcanic eruptions leading to newly formed rock/ islands and 2) melting of glaciers that exposes rock that has not been colonized.* In both of these instances, you are beginning with bare rock, and thus this will take quite some time to reach a climax community, since you will first need to form soil out of the rock.

Secondary succession occurs when the ecosystem has experienced a disturbance where land was previously colonized (and soil remains). A classic example of this is a fire. It is destructive and can kill off all the vegetation in the area, yet because the soil remains, vegetation can reappear quickly. You can imagine how must faster recovery will be as a result of not needing time to form new soil out of bare rock. So you can think of secondary succession as skipping that first (or primary) step. There are several other examples of secondary succession. The damage does not have to be as severe as all the trees being burned down, and could be anything that sets the ecosystem back from its stage of the climax community (other natural disasters or human interactions) and keeps the soil intact.

Answering the Question:

The disturbance includes trees being cut down and fire, and thus the soil should remain intact. As a result, this would be an example of secondary succession, since this is the type of succession characterized by land previously being colonized (they mention it was a rainforest) and the fact that land remains as a grazing pasture for cattle is further evidence that soil remains intact.

Hope this helps!

*Note: One other example that gets grouped into primary succession is vegetation growing from sand dunes. It might not be as obvious as the bare rock, but this is an area without previous vegetation, and that sand is the result of eroded rock. Wanted to include that in case it is another example you come accross.