Option G:Ecology and Conservation
G.1 Community Ecology
What are abiotic factors?
TemperatureSoil pHSalinityMineral componentsWater lightHumidityAmount of precipitationEtc.
G.1.1 Outline the factors that affect the distribution of plant species, including temperature, water, light, soil pH, salinity and mineral nutrients
Abiotic factor Explanation
Temperature Organisms can only survive within a narrow range from which it is adapted to
Light Light intensity/wavelength/duration and quality is important for photosynthesis
Soil pH Most plants only tolerate a narrow pH range
Salinity Most plants can’t tolerate high fluctuations in salinity
Mineral nutrients Affects plant fertility, soil structure, and water retention
Water Limiting factor in most terrestrial ecosystems and plants are classified according to their ability to tolerate water shortage
G.1.2 Explain the factors that affect the distribution of animal species, including temperature, water, breeding sites, food supply and territory
Abiotic/biotic factor
Explanation
Temperature Must be within viable range of adapted animal
Water Must be species-specific quantities
Breeding sites Maintenance of species
Food supply Right kind for species
Territory • Breeding or feeding• Dissolved oxygen affects aquatic species• Salinity may affect some species
G.1.3 Describe one method of random sampling based on quadrat methods, that is used to compare the population size of two plant or two animal species
The Quadrat Method•Squares of a certain size are made•Randomly choose a square•Organisms within the square are counted•This number is used to determine the population size
Why is this method better used for plants rather than animals?
Using the quadrat method, find out how many there are of the following:
Venus flytraps Roses Orchids
Why is this method better used for plants rather than animals?
G.1.4 Outline the use of a transect to correlate the distribution of plant or animal species with an abiotic variable
G.1.5 Explain what is meant by the niche concept, including an organism’s spatial habitat, its feeding activities and its interactions with other species
Spatial habitat: area inhabited by organism
Feeding activities: affects ecosystem by keeping other organisms in check
Interactions: •Competition•Herbivory•Predation•Parasitism•Mutualism
Jigsaw task: You will randomly be placed in expert groups for one type of interaction and you will quickly research and find two examples of it. After you will get back to your home groups and share your findings with them. 1.Competition2.Herbivory3.Predation4.Parasitism5.Mutualism
G.1.6 Outline the following interactions between species, giving two examples of each: competition, herbivory, predation, parasitism and mutualism
G.1.7 Explain the principle of competitive exclusion
No two species in a community can occupy the same niche
G.1.8 Distinguish between fundamental and realized niches*
Fundamental niche:•The potential niche of an organism under ideal conditions with its adaptations
Realised niche:•The actual niche of an organism which is restricted by the environment and competition
G.1.9 Define biomass
The total dry organic matter of organisms/ecosystems (g m-2yr-1)
G.1.10 Describe one method for measurement of biomass of different trophic levels of the ecosystem
• Measure total area of ecosystem (e.g. a forest)• Divide ecosystem into small areas (e.g. grids or plots marked
with a stake carrying a number)• Choose one sample plot• Measure size of each plant species (height and diameter).
Extract all vegetation from plot.• Dry all samples in circulating drying oven at 90°C• Use mathematical model to show relationship between weight
and height of each plant species and its biomass• Sample other plots (size and height only)• For animals, trap them and weight and measure them. Use
tables to determine their biomass• Average data for all species per plot• Multiply the average per plot by the number of plots in
ecosystem