Topic 3 - Biodiversity

Biodiversity

amount of biological or living diversity per unit area

types of biodiversities

• species diversity

• habitat diversity

• genetic diversity

species diversity

variety of species per unit area

habitat diversity

number of ecological niches per unit area in an ecosystem

genetic diversity

range of genetic material present in a gene pool

succession

the process by which the mix of species and habitat in an area changes over time

relationship between ecosystem stability / diversity / sucession / habitat

•Each stage/sere of succession creates a deeper and nutrient-rich soil = allowing larger plants to grow

•This increases the habitat diversity = greater species and genetic diversity (more complex food webs) = greater stability

•more complex food webs = greater diversity, so more stability if one organism goes extinct

factors that lead to loss of diversity

• natural hazards

• loss of habitat

• fragmentation of habitat

• pollution

• agricultural practices

• overexploitation

• introduction to non-native species

• spread of disease

fragmentation of habitat

large area is divided up by roads / other contruction

agricultural practices

• mono-cultures = growth of only 1 species pf crop over a large land area

• pesticides

factors that make species prone to extinction

• limited distribution

• small population size

• habitat specialists

• low reproductive capacity

• poor competitors

• large mammals

• valuable products

• altruistic species

• position in foodchain

limited distribution explain

island species are unable to adapt to changing condition

small population size explain

smaller genetic diversity

habitat specialists explain

organisms that are dependent

valuable products explain

the value that animals have

altruistic species explain

pack creatures survive better in groups

red list

•Categorizes organisms by “risk of extinction”

•Guides conservation efforts

factors used to determine species red list conservation status

• Population size

• Reduction in population size

• Numbers of mature individuals

• Geographic range and degree of fragmentation

• Quality of habitat

• Area of occupancy

speciation

the process by which new species form through natural selection

significance of plate movement on biodiversity

•important in generating new and diverse habitats

•forms barriers, also bridges between previously separated plates (provides opportunities for species to spread)

types of crust

• continental crust

• oceanic crust

continental crust

• older

• lighter

• cannot sink and is permanent

oceanic crust

• younger

• heavier

• can sink and is constantly being destroyed and replaced

4 types of plate movement

• Constructive margins

• Destructive margins

• Collision margins

• Conservative margins

constructive margins

•Two plates move away from each other.

•Molten rock (magma) rises to fill any possible gap and forms oceanic crust

•The Atlantic Ocean widens every year

destructive margins

• Occur where plates consisting of oceanic crust move towards plates of continental crust.

• The oceanic crust is forced downwards, to make subduction zones

• The increase in pressure can trigger earthquakes

• Newly formed magma rises to the surface to form volcanoes

Collision margins

• When two land masses meet the two crush together at what is known as a collisional boundary.

• They crumple and fold

• The result is a mountain range

Conservative margin/boundary

• Fault

• breaks the Earth’s crust.

• Crust is neither created nor destroyed.

• Earthquakes occur along these boundaries and deep (sea) trenches are found here

fault

A place where two plates slip past each other, moving in opposite directions

TRF

Hotspots of biodiversity

TRF characteristics

• usually high numbers of endemic species

• they are threatened areas, where 70% of the habitat has been lost

• tend to have large densities of human habitation nearby

• 50% of all species of plants and animals live in TRF

endemic species

a species that is uniquely found in one part of the world

Layering of rainforests

• Forest Floor/shrub layer

• under canopy

• canopy

• Emergents

Forest Floor/shrub layer explain

dark with very little vegetation between the trees. It receives around 1% of the available solar power

under canopy explain

receives limited sunlight (2-5%)

canopy explain

• where the upper parts of most of the trees are found

• about 20 to 40 meters tall

• Gets about 80% of the light

emergents explain

• the tops of the tallest trees in the rainforest

• photosynthesis occurs in the upper layers

human impact on rainforests

• Loss of habitat

• Loss of species/genetic pool

• Nutrient cycle is interrupted

• Reduced soil fertility

• Soil erosion (greater overland flow)

• Decreasing evaporation/transpiration = reduced rainfall = higher temperatures

causes of human impact on rainforests

• Deforestation/Logging

• Commercial agriculture

• Infrastructure

• Clearing for cattle

• Government land policies

• Shifting cultivation

shifting cultivation

an agricultural system in which plots of land are cultivated temporarily, then abandoned and allowed to revert to their natural vegetation while the cultivator moves on to another plot

Biodiversity calculation

D = N(N-1) / sum of n(n-1)

D

diversity index

N

total number of organisms of all species found

n

total number of individuals of the species of interest