Life Processes In The Biosphere Flashcards
What is the actual size of a population controlled by? (3)
Births
Deaths
Movements in and out area
What is the number of births controlled by?
The natural reproductive potential of a species (biotic potential)
What is the number of deaths controlled by?
Environmental factors
Give examples for density independent factors? (3)
Drought
Good
Volcanic eruption
Give examples of density dependent factors (2)
Food supply
Disease
What is the carrying capacity?
The max population size that can be supported indefinitely without damaging or over-exploiting the environment
What happens if the population drops below that carrying capacity?
The density dependent factors become weaker so mortality decreases and the population increases
What does higher diversity in less abiotically extreme environments result in?
More stable ecosystems in which populations are dominated by biotic factors
What are the abiotic factors that affect the survival of a species? (5)
Temperature Light pH Water Mineral Nutrients
What are the biotic factors that affect the survival of a species? (7)
Feeding Predators Symbiotic Nutrition Pollination Seed Dispersal Disease Nutrient Supply
What is Taxonomy?
The study of how organisms can be group according to how closely related they are
Define Species
A group of organisms that resemble one another more closely than members from other groups
Define Population
Refers to the individuals of a species living in a particular area
Define Community
The populations of all the species of plants and animals living in a particular area
Define Ecosystem
The community of organisms living in an area and their inter-relationships with the environment
Define Habitat
Place where species, organisms or population lives
Define Niche
The role a species plays in its habitat
Define Biome
Large geographical region with particular climatic features
Define Biosphere
Part of the planet that is inhabited by living organisms
What is the climax community usually controlled by?
The climate (climatic climax)
What is the sequence of changing communities called?
A sere
How long does primary succession continue for?
Until the climax community develops
What do species that colonise an area change? What does this lead to?
Change abiotic factors and lead to not favourable conditions, which allow new species to colonise and out-compete others
As abiotic conditions get less extreme, what happens to the diversity of species?
It increases
What is a hydrosere?
A succession that begins in water
What is the first step of a hydrosere?
An area of freshwater us colonised by single celled algae from soil
In a hydrosere, what happens when plants begin to grow?
Water becomes shallower and shade of emergent plants kills submerged plants
In a hydrosere, what happens when the lake starts to fill up with sediment?
Aquatic species disappear and trees starts to colonise
In a hydrosere, how does the soil become drier? What eventually colonises?
More sediments fill in and transpiration by trees removes the water. Oak colonise
What do denser canopies provide? What’s a consequence of this?
Provides shade so smaller plants grow less well
What does the speed with which a species colonises depend on?
The with which they can travel
What is a Lithosere?
The development of the a community on bare rock
What are the early abiotic conditions like in a lithosere? (4)
Very harsh
No soil
Lack of water
Extremes of temperature
What are the first colonisers of a Lithosere called?
Simple Autotrophs (algae and lichens)
What happens in the first stage of Lithosere succession?
Weathered rock fragments and DOM start building up and mosses colonise
What happens when the soil builds up in a Lithosere?
Plants get larger and abiotic conditions become less extreme
What happens when larger plants colonise in a Lithosere?
Seedlings of less hardy plants survive under their shade
What happens when the soil is deep enough in a Lithosere?
The Edaphic factors (soil factors) are suitable and trees can colonise
What do the the first trees of a Lithosere usually have?
Wind-blown seeds
What do areas that have water available all year usually become?
Woodland (temperature controls which type)
What do areas with seasonal rain usually become?
Grassland
What is secondary succession?
The changes that occur in an area that had already reached the climax state
What events interrupt succession and can remove the climax community?
Natural events (forest fires, hurricanes) Human activities (deforestion, grazing, mowing and burning)
What are Plagioclimaxes?
If the human activities that destroyed the climax community continue, a new community of species will develop
What happens if the human activity that produced a Plagioclimax stops?
Secondary succession will eventually re-establish the climax community
What happens if the Plagioclimax community is considered important?
It is necessary to continue the activities that maintained the Plagioclimax
In the UK, what does conservation often involve?
Management of plagioclimaxes and the continuance of previous activities
Why might culling of a population be necessary?
To conserve species or habitats where natural control mechanisms no longer exist
What is Sigmoidal Population Growth?
The growth pattern of a population where abundant resources slow rapid growth followed by population stabilisation as the carrying capacity is reached
