Population Ecology

 
9.2 Population Ecology
 
Introduction to Population Ecology
  • Population ecology is a branch of ecology which studies the interactions of a population with its surroundings. A population is a group of organisms of the same species living in the same habitat.
  • Population distribution shows how the organisms of the same species are able to spread out in a habitat.
 
Factors Affecting Population Distribution of Plants and Animals
Factors The Effects towards Plants
Temperature
  • The optimum temperature for plant growth is between 25 degrees Celsius to 30 degrees Celsius.
  • High temperatures can cause enzymes to break down. Biochemical processes in plants will be disrupted.
  • Low temperatures will reduce enzyme activity. This will slow down the biochemical reaction.
Water
  • Water is needed for enzyme activity, photosynthesis as well as transport and support in herbaceous plants.
  • Dry areas such as deserts and tundra areas such as the poles have low population distribution and plant density.
Light
  • Light is very important for the process of photosynthesis.
  • Areas that receive less light have a small number of plants.
pH of soil
  • Soil pH is important for nutrient uptake by roots.
  • Soil pH that is too acidic or alkaline will cause the absorption of nutrients by plants to be low.
  • Tree growth will be affected due to lack of nutrients.
Mineral salt content
  • The salt content affects the osmotic absorption of water by the roots.
  • The high salt content in the soil causes plants to lose water through osmosis.
  • Minerals are needed to produce proteins, enzymes, nucleotides, vitamins and other compounds.
  • For example, phosphorus is used to form phospholipids (in the formation of cell membranes).
Faktor The Effects towards Animals
Temperature
  • Areas exposed to high temperatures in a habitat are less occupied by animals such as worms and snails.
Water
  • Animals are concentrated in areas that have sufficient water resources to drink and cool down.
Breeding site
  • A suitable and safe breeding place is needed by animals to give birth and raise children.
Food supply
  • Food is important for survival because animals are heterotrophic that depend on plants and other animals as food.
 
The image is a diagram titled ‘Patterns for Population Distribution.’ It is divided into three sections, each labeled with a number and a type of population distribution. From left to right, the sections are: 1. Clumped 2. Random 3. Uniform Each section has a corresponding orange header with the number and type of distribution written below it. The background is light, and there is a logo at the bottom right corner with the text ‘Pandai.’
 
Patterns for Population Distribution
Patterns Explaination

Clumped

tambah gambar

  • Clumped organisms form separated groups.
  • This condition is caused by uneven distribution of resources in an area.

Random

tambah gambar

  • Organisms are distributed in a free pattern in an area.
  • This distribution involves species that have little interaction among individuals.

Uniform

tambah gambar

  • Organisms are distributed all over an inhabited area.
  • This distribution involves species in which every individual competes for limited resources in an area.
 
Estimation of Organism Population Size
  • Two important factors for studying population ecology which are:
    • Population size:
      • The number of organisms present in a population.
    • Population density:
      • The number of individuals of a species per unit area of a habitat.
  • The population size in an area can be estimated by a random sampling technique when the studied area is large and difficult to obtain data.
  • A sample which represents the area is taken to give an estimation of the abundance and the distribution pattern of certain organisms that inhabit the area
 
Quadrat Sampling Technique
  • A quadrat sampling technique can estimate the population size of land plants or animals which are inactive or move slowly.
  • The number of organisms in the quadrat areas is the sample which represents the whole area of study.
  • The data obtained from all quadrats can be used to estimate the population in the area of study.
  • A quadrat is a square-framed structure which is made of wood, iron or plastic.
  • Normally, a quadrat is subdivided into a few parts of the same size to estimate the coverage percentage of any species.
  • The size of the quadrat depends on the types and size of organisms, the area of study as well as the distribution and density of the plants being studied.
  • For example, a one-metre-squared quadrat is suitable to estimate the population of plants in a school field
Frequency
  • Frequency is the probability to get an individual of any plant species in every quadrat.
  • Frequency = [The number of quadrats containing studied species/Total number of quadrats used] x 100%
Density
  • Density is the average number of individuals in any species per unit area of study
  • Density = Total number of individual species studied in all quadrats/(Total number of quadrats used x Area of a quadrat)
Coverage
  • Coverage is the surface area of the soil which is covered by the shoots of the plant species.
  • The coverage percentage is the percentage of soil surface covered by the plants.
  • Coverage percentage = [Area covered by studied species in all quadrats/(Total number of quadrats used × Area of a quadrat)] x 100%

 

 

 

 

 

Population Ecology

 
9.2 Population Ecology
 
Introduction to Population Ecology
  • Population ecology is a branch of ecology which studies the interactions of a population with its surroundings. A population is a group of organisms of the same species living in the same habitat.
  • Population distribution shows how the organisms of the same species are able to spread out in a habitat.
 
Factors Affecting Population Distribution of Plants and Animals
Factors The Effects towards Plants
Temperature
  • The optimum temperature for plant growth is between 25 degrees Celsius to 30 degrees Celsius.
  • High temperatures can cause enzymes to break down. Biochemical processes in plants will be disrupted.
  • Low temperatures will reduce enzyme activity. This will slow down the biochemical reaction.
Water
  • Water is needed for enzyme activity, photosynthesis as well as transport and support in herbaceous plants.
  • Dry areas such as deserts and tundra areas such as the poles have low population distribution and plant density.
Light
  • Light is very important for the process of photosynthesis.
  • Areas that receive less light have a small number of plants.
pH of soil
  • Soil pH is important for nutrient uptake by roots.
  • Soil pH that is too acidic or alkaline will cause the absorption of nutrients by plants to be low.
  • Tree growth will be affected due to lack of nutrients.
Mineral salt content
  • The salt content affects the osmotic absorption of water by the roots.
  • The high salt content in the soil causes plants to lose water through osmosis.
  • Minerals are needed to produce proteins, enzymes, nucleotides, vitamins and other compounds.
  • For example, phosphorus is used to form phospholipids (in the formation of cell membranes).
Faktor The Effects towards Animals
Temperature
  • Areas exposed to high temperatures in a habitat are less occupied by animals such as worms and snails.
Water
  • Animals are concentrated in areas that have sufficient water resources to drink and cool down.
Breeding site
  • A suitable and safe breeding place is needed by animals to give birth and raise children.
Food supply
  • Food is important for survival because animals are heterotrophic that depend on plants and other animals as food.
 
The image is a diagram titled ‘Patterns for Population Distribution.’ It is divided into three sections, each labeled with a number and a type of population distribution. From left to right, the sections are: 1. Clumped 2. Random 3. Uniform Each section has a corresponding orange header with the number and type of distribution written below it. The background is light, and there is a logo at the bottom right corner with the text ‘Pandai.’
 
Patterns for Population Distribution
Patterns Explaination

Clumped

tambah gambar

  • Clumped organisms form separated groups.
  • This condition is caused by uneven distribution of resources in an area.

Random

tambah gambar

  • Organisms are distributed in a free pattern in an area.
  • This distribution involves species that have little interaction among individuals.

Uniform

tambah gambar

  • Organisms are distributed all over an inhabited area.
  • This distribution involves species in which every individual competes for limited resources in an area.
 
Estimation of Organism Population Size
  • Two important factors for studying population ecology which are:
    • Population size:
      • The number of organisms present in a population.
    • Population density:
      • The number of individuals of a species per unit area of a habitat.
  • The population size in an area can be estimated by a random sampling technique when the studied area is large and difficult to obtain data.
  • A sample which represents the area is taken to give an estimation of the abundance and the distribution pattern of certain organisms that inhabit the area
 
Quadrat Sampling Technique
  • A quadrat sampling technique can estimate the population size of land plants or animals which are inactive or move slowly.
  • The number of organisms in the quadrat areas is the sample which represents the whole area of study.
  • The data obtained from all quadrats can be used to estimate the population in the area of study.
  • A quadrat is a square-framed structure which is made of wood, iron or plastic.
  • Normally, a quadrat is subdivided into a few parts of the same size to estimate the coverage percentage of any species.
  • The size of the quadrat depends on the types and size of organisms, the area of study as well as the distribution and density of the plants being studied.
  • For example, a one-metre-squared quadrat is suitable to estimate the population of plants in a school field
Frequency
  • Frequency is the probability to get an individual of any plant species in every quadrat.
  • Frequency = [The number of quadrats containing studied species/Total number of quadrats used] x 100%
Density
  • Density is the average number of individuals in any species per unit area of study
  • Density = Total number of individual species studied in all quadrats/(Total number of quadrats used x Area of a quadrat)
Coverage
  • Coverage is the surface area of the soil which is covered by the shoots of the plant species.
  • The coverage percentage is the percentage of soil surface covered by the plants.
  • Coverage percentage = [Area covered by studied species in all quadrats/(Total number of quadrats used × Area of a quadrat)] x 100%