Article - Eagle

by Jovan Tang 

Have you ever wondered how life starts on a new piece of land? For example, if a volcano erupts in the middle of the ocean, how do plants start growing there and how do animals start living there? Well, new life in a barren area is achieved through the ecological process of primary succession - the beginning step in the process of change over time in an ecosystem after an extreme disturbance. 

The first thing succession needs though is a medium in which nutrients can be cycled and plants can root themselves in. This medium is usually soil. Then there are the 3 stages of primary succession: the pioneer stage, the intermediate stage, and finally the climax community. Each stage is also called a sere, and as an ecosystem progresses along the seres biodiversity and ecological resilience increase and we start to see more life being present in the area. 

Pioneer Stage/Sere

This is the stage in which plants start to colonise the new environment (usually lichens, mosses, and other small herbs). Colonisation occurs because of wind, animal, and ocean dispersal of seeds and plants. These small plants secrete acid which starts to break down the rock and creates new soil, and as these plants die, they decompose and add more organic material and nutrients to the soil. This is an example of an autogenic change - changes driven by biotic factors. In this stage, the gross productivity is low, the soil is shallow, there is limited mineral cycling, and there is not a lot of species diversity. 

Intermediate Stage/Sere

The intermediate stage/sere is where we start to see more biodiversity occur and more grasses and shrubs start to appear. Small birds and plants also start arriving in the area. Because of the addition of these species, species diversity increases and interactions between the different species increase. All these new species interacting with each other, dying and decomposing, etc. also help the nutrient cycling process and increase soil depth. 

Climax Community 

The climax community stage is where the ecosystem has reached a stable environment with an equilibrium that allows species to exist together without changing much. At this stage, energy flows between animals are complex and efficient, there is high biodiversity, efficient mineral cycling, and deep soil with a rich organic layer. This is the most resilient stage of an ecosystem. 

However, it is hard to understand these terms without an example, so I have attached an infographic on primary succession occurring on Surtsey Island, an island which formed off the coast of Iceland due to a volcanic eruption. Hopefully now you have an understanding of how life can form in a barren area, even if you've never wondered about it before!