2.4 biomes, zonation and succession

Question 1

what is a biome?

Answer 1

A biome is a collection of ecosystems sharing similar climatic conditions

Question 2

what are the 6 major types of biome which can be further sub-divided?

Answer 2

Aquatic (freshwater = lakes, ponds, streams…
marine = coral reef, deep ocean, mangrove swamps…)
Deserts (hot and cold)
Forests (tropical, temperate and boreal/taiga)
Grassland (tropical or savanna and temperate)
Tundra (arctic and alpine)

Question 3

what is the general reason behind biome distrobution?

Answer 3

Biome distribution is massively influenced by productivity, which is influenced by photosynthesis

Question 4

why are some biomes where they are?

Answer 4

temperature, insolation and precipitation- all factors of photosynthesis

Latitude – distance north or south from equator
Altitude – height above sea level

Question 5

explain how the equator works?

Answer 5

At the equator, solar radiation hits the Earth at a 90 degree angle, so is more intense
As you move further away from the equator (increase latitude) the rays hit the Earth at a different angle, so are spread out over a greater surface

Question 6

what is the angle of incidence?

Answer 6

the angle formed by rays of sunlight hitting the Earth is known as the angle of incidence

Question 7

what is a Whittaker diagram?

Answer 7

I diagram that plots biomes against
temperature and precipitation.

Question 8

what is the relationship between latitude and productivity?

Answer 8

Greater at low latitudes 30 degrees (tempreate zone)
-temp, sunlight and precipitation here is high
-ideal for photosynthesis

Moving towards the poles:
-temp, sunlight and precipitation decline, reducing photosynthesis
-GPP and NPP values lower

Question 9

Why might there not be high productivity in an area which has high rainfall BUT is also very warm and/or windy?

Answer 9

There will be lots of evaporation so the water may not be available for long!

So we need to take into account the precipitation:evaporation ratio

Question 10

what is the tricellular model? what does it do? and what is the effect?

Answer 10

A complex system of atmospheric circulation

Causes different precipitation/temperatures which in turn influence structure and productivity of biomes.

Tricellular circulation creates climate patterns which in turn determine which vegetation type will grow

Question 11

what happens in the haddly cell of the tricellualar model?

Answer 11

At the equator: (Haddly cells)
Warm air rising causes high precipitation
High insolation and intense heat due to angle of sun
Gives rise to rainforests

drops temp and goes back to equator to start cycle again.

Question 12

what happens as you move away from the equator in the ferrel cell?

Answer 12

Moving away from the equator (increasing latitude):
Air cools and sinks forming “dry air”
This creates arid conditions giving rise to deserts

Question 13

what happens at the pole cell on a tricellular model?

Answer 13

At the poles:
Dry air creates water limiting conditions in the tundra

Question 14

how is climate changing due to climate change?

Answer 14

Warming at higher latitudes
Some area’s becoming drier, others wetter
Stronger storms

Question 15

how are organisms adapting to the changes caused by climate change?

Answer 15

Towards poles where it is cooler
Higher up mountains where it is cooler

This is easier for animals (although they can still face obstacles like mountain ranges and seas) and more difficult for plants who can only migrate very slowly through wind or animal seed dispers

Question 16

what are the benefits of climate change changing biomes?

Answer 16

Decrease of sea ice is making drilling for oil under the Arctic Ocean possible
The North-West passage for ships between the North Pole and North America could become a trade route without icing up

Question 17

what is zonation? and what cause a change in zonation?

Answer 17

Zonation = how an ecosystem changes along a gradient, the change in community along an environmental gradient due to factors such as changes in altitude, latitude, tidal level or distance from shore/coverage by water

Question 18

what is succession?

Answer 18

Succession = how an ecosystem changes over time

process of change over time in an ecosystem involving pioneer, intermediate and climax communities

Question 19

why does zonation effect where organisms are found?

Answer 19

Species have an ecological niche outside the boundaries of which, they cannot live. This is why certain organisms are only found in certain places

Question 20

what effects the boundaries where an organism can be found and can you give examples and what affects these boundaries?

Answer 20

There are biotic and abiotic factors which influence these boundaries (niches)

Temperature (colder higher up)
Precipitation (less higher up)
Solar insolation (more higher up)
Soil type (more acidic higher up)
Interaction between species (competition at different areas)

Question 21

how may zonation change in a aquatic biome?

Answer 21

In an aquatic area zonation may be because of:
Depth of water
Position in relation to land
Latitude (temp)

Question 22

what can a kite diagram be used for?

Answer 22

kite diagrams can be used to show how species abundance changes along a gradient
-the “wider” a part of the kite is, the more abundant a species is

Question 23

what are the two types of succession?

Answer 23

Primary succession – occurs on bare ground ie. A volcano

Secondary succession – occurs where there’s already soil but all vegetation has been removed ie. a forest fire

Question 24

what is the first step in primary succession?

Answer 24

Colonization

First species called pioneers adapted to the extreme, bare conditions.

Pioneers are r-selected species. This means they produce large numbers of offspring and can colonize an area quickly using short-lived resources.
For example mosses, lichens

Simple soil forms from windblown dust and mineral particles.

Question 25

what are some characteristics of r-stratgist species?

Answer 25

short life, rapid growth

Question 26

wha are some characteristics of k-stratagist species?

Answer 26

long life, slower growth

Question 27

what is the second step in primary succession?

Answer 27

2. Establishment

Species diversity increases
Invertebrates start to live in soil which increases the humus content (when they die and decompose).
Weathering will increase nutrients in soil.

Question 28

what is the third step in primary succession? and what happens?

Answer 28

3. Competition

Microclimate changes as new species colonize

Soil depth increases
.
Big plants increase cover and provide shelter allowing K-selected species to become established

Pioneer r-species unable to compete and lost from community

Question 29

what is the forth step in primary succession?

Answer 29

4. Stabilization

Complex food webs develop

Soil depth and humus content continues to increase

Less sand blown so soil can hold more water

Question 30

where do intermediate communities come?

Answer 30

Intermediate communities come between pioneer and climax.

Question 31

what are some features of a climax community?

Answer 31

In steady-state dynamic equilibrium

Recycling of soil nutrients and leaf litter decomposition makes fertile soil

Represents maximum possible development that can be reached under given conditions

Are the most stable community due to greater number of species, complex food webs, most favourable abiotic conditions etc

Question 32

what are some examples of climax communities which have achieved stability over thousands/millions of years?

Answer 32

the Sonoran Desert, Mexico

Question 33

what are some expels of where primary succession happen?

Answer 33

New lakes, ponds, cooled lava,
sand dunes, bare rock…

Question 34

can you give an example of primary succession?

Answer 34

Rock → lichen → moss → grass →
shrubs → trees → oak hickory forest

Question 35

what is secondary succession? and why does it differ from primary succession?

Answer 35

Established community suddenly destroyed e.g. forest fire, flood, deforestation
Shorter version of succession
Soils already developed and ready to accept seeds

Question 36

what changes occur over succession?

Answer 36

Energy flow becomes more complex (more trophic levels, more species etc)

Mineral content and cycling of soil increases. More leaf litter and soil organisms

Greater habitat diversity leads to greater species and genetic diversity

Question 37

what is GPP?

Answer 37

Gross primary productivity = All the biomass produced by producers before any is used up for respiration.

Question 38

what is NPP?

Answer 38

Net primary productivity = Takes into account losses through respiration (basically is really what the plant is “left with” to use for increasing its biomass/growing)

Question 39

what productivity like in the early ages of succession?

Answer 39

GPP is low due to poor conditions for photosynthesis (soil can’t hold water) and few producers.

Proportion of energy lost through respiration also low as there are few organisms, so NPP is high (proportionally)

Question 40

what is the effect of succession on productivity in the late stages?

Answer 40

In later stages:
GPP rises due to increased producers and conditions
However now high rate of respiration due to presence of community, so NPP lowers

Question 41

what is the NPP and GPP in the early stages of succession like?

Answer 41

Low GPP but high % of NPP.
Little Increase in Biomass.
Grasses, herbs, small shrubs grow.

Question 42

what is the NPP and the GPP in the middle stages of succession like?

Answer 42

GPP is high.
Increased photosynthesis. Increases in biomass as plants become larger.
As woodland species and biomass increases, so does productivity, but NPP as a % of GPP falls as respiration rates increase.

Question 43

what are the consequences of the NPP and GPP in the late stages of succession?

Answer 43

Trees reach their maximum size.
Ratio of NPP to R is roughly equal.

Question 44

how do humans impact succession?

Answer 44

Hunting
Agriculture (grazing, deforestation)

Question 45

what is resilience?

Answer 45

If succession is disrupted, the ecosystem may or may not recover quickly depending on its resilience.
Resilience is the ability of a system to return to its initial state after a disturbance