The autogenic and allogenic successions are the types of ecological succession based on the factors influencing the same. Autogenic succession is the one that is driven by biotic elements or living organisms in that specific community. Allogenic succession, on the other hand, is the ecological succession that is influenced by abiotic or external community influences. This article will explain to you about Autogenic and Allogenic Succession which will be helpful in preparing the Environment syllabus for the UPSC Civil service exam.

What is Autogenic Succession?

• The primary driver of change in autogenic succession comes from within the community.
• Autogenic succession can be seen in the transition from an abandoned agricultural field to a mature forest.
• As a result, autogenic succession occurs on time scales that correspond to the life spans of the community's organisms.

Factors Inducing Autogenic Succession

• This succession is triggered by the plants themselves (biotic components).
• Light trapped by leaves
• Detritus production
• Uptake of water and nutrients
• Fixation of nitrogen
• Climate change caused by humans
• These factors result in a steady ecological change in a specific area of land, which is referred to as a succession of dwelling species.
• Because of the pre-existing plant life, autogenic succession is considered a secondary succession.

What is Allogenic Succession?

• Allogenic succession refers to succession that occurs as a result of factors outside the community.
• The primary driving force of change in allogenic succession is external to the community.
• Allogenic succession happens on a time scale that corresponds to or is proportional to the disturbance's time scale.
• Climate change-induced allogenic succession can take thousands of years to occur.
• The succession of phytoplankton populations in freshwater lakes is caused by seasonal changes in temperature and light intensity.

Factors Inducing Allogenic Succession

• An allogenic succession can be induced in a variety of ways, including:
• Flooding
• Drought
• Volcanic eruptions
• Earthquakes
• Meteor or comet strike
• Non-anthropogenic climate change

Difference Between Autogenic and Allogenic Succession

Conclusion

Despite the fact that succession is frequently thought to be an out-of-date topic, new studies and reviews show that it continues to play an important role in modern ecological theory and practice. Thus ecological succession is critical for an ecosystem's growth and development as it kickstarts the colonization of new places as well as the recolonization of areas that have been damaged by biotic and environmental conditions.

FAQs

MCQs

1. Which type of succession is driven by changes within the ecosystem itself?

A) Autogenic Succession
B) Allogenic Succession
C) Primary Succession
D) Secondary Succession

2. Which of the following is an example of allogenic succession?

A) Soil enrichment by plants
B) Flood-induced vegetation change
C) Tree growth in abandoned fields
D) Grassland conversion to forest

3. Which factor is least likely to drive autogenic succession?

A) Soil nutrient levels
B) Plant canopy structure
C) Earthquake disturbance
D) Light availability

4. Allogenic succession is most commonly related to:

A) Internal plant growth
B) Biotic interactions
C) External environmental changes
D) Species interactions

5. Which of these is a common driver of autogenic succession?

A) Seasonal floods
B) Plant detritus
C) Earthquakes
D) Soil erosion by wind

GS Mains Questions and Model Answers

Q1: Discuss the significance of autogenic and allogenic succession in ecosystem development.

Answer: Autogenic and allogenic successions are vital to ecosystem development as they drive ecological succession in different contexts. Autogenic succession, controlled by internal biotic factors, contributes to gradual ecosystem changes, fostering stability. Allogenic succession, however, is driven by external factors like natural disturbances, leading to new ecological opportunities. Both processes contribute to biodiversity, ecological resilience, and adaptability in varied environments, reflecting nature’s adaptive cycles.

Q2: How does ecological succession help in ecosystem stability and resilience?

Answer: Ecological succession enhances ecosystem stability by promoting species diversity and fostering complex interdependencies. Autogenic succession, through nutrient cycling and habitat creation, provides long-term ecosystem stability. Allogenic succession allows ecosystems to adapt to disturbances, contributing to resilience. Together, these successions allow ecosystems to self-organize, regenerate after disturbances, and maintain ecological balance, promoting adaptability to environmental changes.

Q3: Explain the role of natural disturbances in allogenic succession with examples.

Answer: Natural disturbances, like fires, floods, and volcanic eruptions, are primary drivers of allogenic succession. These external factors create habitat changes, allowing new species to colonize. For instance, forest fires clear old vegetation, enabling pioneer species to establish, gradually leading to ecosystem recovery. Floods can alter soil composition, promoting species adapted to waterlogged conditions. These processes contribute to biodiversity and ecosystem regeneration, highlighting the adaptive nature of ecosystems.

Previous Year Questions on Autogenic and Allogenic Succession

1. UPSC CSE Prelims 2020:

Question: In ecology, autogenic succession is driven by:

A) External disturbances
B) Internal biotic factors
C) Climatic conditions
D) Abiotic factors

Answer: (B)

Explanation: Autogenic succession is initiated by biotic factors within the community, such as vegetation influencing its habitat through nutrient cycling and soil enrichment.

2. UPSC CSE Mains 2019 (GS Paper 3):

Question: "Compare autogenic and allogenic succession. Discuss their roles in ecological restoration."

Answer: Autogenic succession is internally driven by biotic interactions within a community, supporting gradual ecological transitions. Allogenic succession, on the other hand, is caused by external forces, such as natural disturbances, shaping new ecological habitats. Both processes are integral to ecological restoration, with autogenic succession fostering stability, while allogenic succession allows systems to adapt post-disturbances. Together, they enhance biodiversity and ecosystem resilience, vital for successful restoration.