Difference Between Autogenic and Allogenic Succession

The key difference between autogenic and allogenic succession is that autogenic succession takes place due to biotic components such as plants and accumulation of litter, etc. in the ecosystem while allogenic succession takes place due to abiotic components such as volcanoes, flooding, forest fires, and human interferences, etc. in the ecosystem.

Ecological succession refers to the evolution of the structure of a biological community over time. There are two types of succession as primary succession and secondary succession. Primary succession is the colonization of an area that has not been previously occupied by an ecological community while secondary succession is the colonization of an area following a severe disturbance or removal of the previous community. When considering the contribution of biotic and abiotic components in an ecosystem for the succession, there are two types of succession as autogenic and allogenic succession. Abiotic components drive allogenic succession while biotic components drive autogenic succession.

CONTENTS

1. Overview and Key Difference
2. What is Autogenic Succession
3. What is Allogenic Succession
4. Similarities Between Autogenic and Allogenic Succession
5. Side by Side Comparison – Autogenic vs Allogenic Succession in Tabular Form
6. Summary

What is Autogenic Succession?

Autogenic succession is the ecological succession driven by biotic components of the ecosystem. Living organisms are responsible for the changes occurring in the composition of an ecological community. When a large tree matures, branches of the tree produce shade on the floor in a vast area. Then the shade-tolerant-plant species grow nicely on that area.

Moreover, organic matter accumulated in the soil due to dead plant and animal matter changes the soil nutrients, soil microorganisms, soil pH, etc., in the soil. Therefore, the changes occurring in the soil cause autogenic succession. Secondary succession starts with autogenic succession.

What is Allogenic Succession?

Allogenic succession is the ecological succession driven by physical factors within the community. In other words, allogenic succession is the succession driven by abiotic factors such as volcanoes, flooding, forest fires, global warming, greenhouse effect, drought, earthquakes, non-anthropogenic climate change, leaching and soil erosion, etc.

Vegetation or other living organisms do not influence allogenic succession. It can happen on a time scale that is proportionate with the disturbance.

What are the Similarities Between Autogenic and Allogenic Succession?

• Autogenic and allogenic succession are two types of ecological succession caused by biotic and abiotic factors, respectively.
• They bring changes in the ecological community over time.

What is the Difference Between Autogenic and Allogenic Succession?

Autogenic succession is the ecological succession driven by biotic factors or living organisms in that specific community. Allogenic succession, on the other hand, is the ecological succession driven by abiotic factors or external factors of the community. So, this is the key difference between autogenic and allogenic succession. Besides, biotic factors such as vegetation and organic matter accumulated in the soil modify the ecological community in autogenic succession while external factors such as volcanoes, flooding, forest fires and global warming, modify the ecological community in allogenic succession.

Moreover, when considering primary and secondary successions, secondary succession starts with autogenic succession while primary succession starts with allogenic succession and proceeds to autogenic succession. Thus, this is another difference between autogenic and allogenic succession.

Summary – Autogenic vs Allogenic Succession

Autogenic succession is the ecological succession driven by the organisms itself living in that area. Therefore, living organisms in the community themselves are responsible for the changes occurring in the ecological community. This autogenic succession may be due to the alteration of soil nutrients, changes in the soil pH, accumulation of organic matter, etc. In contrast to autogenic succession, allogenic succession is the ecological succession driven by external factors or abiotic factors such as volcanoes, flooding, forest fires, greenhouse effect, global warming, etc. These external factors modify the ecological community over time. Thus, this summarizes the difference between autogenic and allogenic succession.

Reference:

1. “Ecological Succession”. En.Wikipedia.Org, 2020, Available here.

Image Courtesy:

1. “Secondary Succession”  By Katelyn Murphy – Own work (CC BY-SA 3.0) via Commons Wikimedia

2. “Forest succession depicted over time” By LucasMartinFrey – Own work (CC BY 3.0) via Commons Wikimedia