Option G

Ecology and Conservation

Distribution of Plant Species

• Distribution of species is the range of places a species inhabits

• Linked directly to abiotic factors• Abiotic Factors:

– Temperature, water, light, soil pH, salinity and mineral nutrients

Distribution of Animal Species

• Temperature: effects all animals, only some can survive in extreme temperatures

• Water: animals vary in the amount of water they require

• Breeding sites: all species breed at some stage in their life cycle

• Food supply: many need specific foods and can only live in areas where these foods are obtainable

• Territory: some animals establish and defend territories for feeding or breeding (creates an even distribution)

Random Sampling Using Quadrats

• In a random sample, every individual in a population has an equal chance of being selected

• Quadrats: square frames used to mark out sample areas

Transects and Distributions

• Transect: line marked out across a site which indicates where to investigate plant/animal distributions along– Useful when there is a gradient in an abiotic

factor

The Niche Concept

• Ecological niche: the mode of existence of a species in an ecosystem– Habitat: where the species lives in an ecosystem– Nutrition: how the species obtains its food– Relationships: interactions with other species in the

ecosystem

• Two species with a similar niche will compete in the overlapping parts, yet will most likely coexist

• Two species with exactly the same niche will always compete and one will become superior

• Competitive exclusions principle: only one species can occupy a niche in an ecosystem

Fundamental and Realized Niches

• Fundamental niche: potential mode of existence, given the adaptations of the species

• Realized niche: actual mode of existence, results from its adaptations and competition from other species

• Differences between the two niches are due to competition

Interactions Between Species• Herbivory: primary consumer feeding on a plant or other

producer – relies on producer’s growth

• Predation: consumer feeding on another consumer – relies on number of prey

• Parasitism: organism that lives on or in a host and obtains food from it– Host is always harmed

• Competition: two species using the same resource compete– When one species uses more of a resource the other species suffers

• Mutualism: members of different species that live together in a close relationship– Both benefit

Measuring Biomass

• Biomass: total dry mass of organic matter in organisms or ecosystems1. Representative samples are collected

2. Organisms are sorted into trophic levels

3. Organisms are dried in an oven from 60-80 Celcius

4. Mass is measured with an electronic balance

5. Drying and measuring may be repeated

Constructing Pyramids of Energy

• The lowest bar of a pyramid of energy is the gross production (total amount of organic matter produced by plants)

• Energy flow measured in kilojoules of energy per square meter per year

• Net production: amount of gross production in an ecosystem after subtracting the amount used by plants in respiration

• Upper bars of a pyramid are the energy that flow through groups of consumers; amount of energy in the food they eat

Difficulties with Trophic Levels

• Many species exist partly in one trophic level and partly in another

• Examples:1. Chimpanzees eat fruit and plants, but also

termites and larger animals; both first and second consumers

2. Oysters consume ultraplanktonic producers, microplanktonic consumers, and dead organic matter; first and second consumers as well as detritivores

Ecological Succession

• Ecological Succession: series of changes to an ecosystem– Primary succession: starts in an environment where living

organisms have not previously existed• New island created by volcanic activity

– Secondary succession: areas where an ecosystem is present, but is replaced by other ecosystems, because of a change in conditions

• Abandoned farmland developing into a forest

• Common changes: soil erosion is reduced due to roots of large plants; amount of organic matter in soil increases as plants/organisms release more organic matter

Biomes and Biosphere

• Biome: a type of ecosystem– Determined mainly by rainfall and

temperature of the area

• Biosphere: made up of the biomes of the world together

Major Biomes of the World

• Desert: low rainfall, warm/hot days, cold nights, few plants• Grassland: low rainfall, warm/hot summers, cold winters,

grasses/herbs• Shrubland: cool wet winters, hot dry summers, fires, drought-

resistant shrubs and evergreen foliage• Temperature deciduous forest: moderate rainfall, warm

summers, cool winters, trees that shed their leaves, shrubs and herbs

• Tropical rainforest: High rainfall, hot in all seasons, huge diversity of plants

• Tundra: low temps, little precipitation (mostly as snow), small trees, few herbs, mosses and lichens are present

Biodiversity

• Abbreviation of the term “biological diversity” from 1986

• Encompasses the diversity of ecosystems on Earth, the diversity of species within them, and genetic diversity of each species

The Simpson Diversity Index

• Overall measure of species richness in an ecosystem1. Collect random sample for organisms

2. Identify each of the organisms found

3. Count total number

4. Calculate D (the index)

N = total number of organisms

n = number of individuals per species

Reasons to Conserve Rainforest

• Economic reasons: new commodities may be found (medicine, raw materials), new crops or farm animals, ecotourism

• Ecological reasons: fix large amounts of carbon dioxide, damage can cause soil erosion, silting up of rivers, flooding, change in weather patterns

• Ethical reasons: every species has a right to live, cultural importance to indigenous humans, deprive future humans the experience

• Aesthetic reasons: beautiful and enjoyable species, artists find inspiration here

Biomagnification

• Biomagnification: the process by which chemical substances become more concentrated at each trophic level

• PCBs are chemicals that were used as insulators used until 1970s that are now detectable throughout the world; Persistent and very toxic

Impacts of Alien Species

• Alien species: one that humans have introduced to an area where it does not naturally occur

• Causes interspecific competition and species extinction

• Rats introduced to New Zealand killed off bird species (Big South Cape Island)

Ozone and Ultra-Violet Radiation

• Ultra-violet radiation damage:– Increases mutation rates by damaging DNA– Causes cancer (especially skin cancer)– Severe sunburns and cataracts of the eye– Reduces photosynthesis rates and so affects

food chains

• Without the Ozone layer there would be a greater amount of ultra-violet radiation

• CFCs are the main cause of ozone depletion