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