Overview
Define the term succession. Distinguish between primary and secondary succession. Describe the series of changes that often culminate in a stable ecosystem. Discover a definite sequence of plant colonization. Describe the characteristics of a stable community and recognize the climax of succession. Define the term overcrowding. State factors that may cause overcrowding. State the effects of overcrowding. State measures adopted in nature to avoid overcrowding. State the causes of food shortage. List the effects of food shortage. Infer that food has a direct influence on mortality on animal population.
What you'll learn
- Succession: (i) Meaning of succession (ii) Structural changes in species composition, variety and increase in number. (iii) Primary succession - in an aquatic habitat, - in a terrestrial habitat. (iv) Secondary succession - meaning and examples. (v) Characteristics of a stable community.
- Overcrowding: (i) Population density studies vis-a-vis available resources. (ii) Importance of factors affecting population e.g. Space.
- Explain the relationship between competition and succession.
- Factors that may cause overcrowding e.g. increased mortality, reduced death rate, absence of predators, etc.
- Discuss measures adopted by nature to avoid overcrowding e.g. dispersal of seeds and fruits, migration of organisms during unfavorable periods, territorial behavior in some organisms e.g. lizards.
- Discuss the effects of food shortage: (i) Competition. (ii) Reproduction. (iii) Emigration. (iv) Increase in mortality rate.
