Biomes, zonation and succession Flashcards
1
Q
What is a biome?
A
A biome is a collection of ecosystems sharing similar climatic conditions
2
Q
What is the biosphere?
A
The biosphere is the part of the Earth inhabited by organisms.
It extends from the upper part of the atmosphere down to the deepest parts of the oceans which support life
3
Q
How many types of biome are there?
A
There are 5 major types (with sub-divisions in each type)
> Aquatic > Deserts > Forests > Grassland > Tundra
4
Q
What are the 5 major types of biome? // AQUATIC
A
Freshwater
- swamp forests, lakes, rivers, bogs
Marine
- coral reef, mangrove swamps, continental shelf, mud flats, deep ocean, rocky shore
5
Q
What are the 5 major types of biome? // DESERTS
A
hot and cold deserts
6
Q
What are the 5 major types of biome? // FORESTS
A
tropical
temperate
boreal
7
Q
What are the 5 major types of biome? // GRASSLAND
A
Tropical
Savanna
Temperate
8
Q
What are the 5 major types of biome? // TUNDRA
A
Arctic
Alpine
9
Q
What are the 3 main factors governing the distribution of biomes?
A
Insolation
Precipitation
Temperature
10
Q
Why is the temperature hotter nearer the equator and gets cooler towards the poles?
A
- At equator, solar radiation hits Earth at 90 degree angle so is most intense
- Elsewhere on Earth, the rays hit Earth at more acute angle so are spread over a greater surface area
11
Q
What is latitude?
A
Distance north or south from the equator
12
Q
What is altitude?
A
Height above sea level
13
Q
How do latitude and altitude both influence climate and biomes?
A
It generally gets colder as you increase latitude or altitude
e.g. there is snow on Mount Kilimanjaro + Himalayas and they have alpine // polar biomes despite being near equator
14
Q
How do ocean currents and winds distribute surplus heat energy from the equator to the poles?
A
- Winds blow from high to low pressure areas + cause ocean currents
- As water changes from state to state, it either gives out or takes in heat
- As water changes from solid to gas, it takes in heat as more energy needed to break molecular bonds
- As water changes from gas to solid, it gives out more heat to surroundings
15
Q
When is the Precipitation to Evaporation (P/E) ratio approximately 1?
A
When precipitation is about the same as evaporation
The soils tend to be rich and fertile
16
Q
What may be limiting factors to growth in the South Pole during winter?
A
Solar radiation
Heat
17
Q
What may be a limiting factor to growth in the desert?
A
Water
18
Q
What happens when the P/E ratio is much greater than 1?
A
e.g. Tundra, Norway
P/E ratio = 1.25
- it rains a lot + evaporation rates are low
- leaching in soil when soluble minerals are washed downwards
19
Q
What happens when the P/E ratio is much lower than 1?
A
e.g Desert, Jordan
P/E ration = 0.1
- water moves upwards through soil and then evaporates from surface
- this leaves salts behind + salinity increases to point where plants can’t grow (salinisation)
20
Q
Where is productivity greatest?
A
- Low altitudes (near equator)
- Temperatures high throughout the year
- Sunlight input is high
- Precipitation is high
These conditions are ideal for photosynthesis
21
Q
5 ways climate is changing
A
> Temp inc. of 1.5 to 4.5 degrees by 2100 > Greater warming at higher latitudes > More warming in winter than summer > Some areas drier, others wetter > Stronger storms
22
Q
How are organisms adapting to the fast change in climate caused by global warming?
A
- Moving towards poles where it’s cooler
- Higher up mountains where it’s cooler
- Towards equator where it’s wetter
23
Q
2 examples of biomes shifting
A
- Africa in the Sahel region, woodlands are becoming savannas
- In Arctic, tundra is becoming shrubland
24
Q
Plants can only migrate very slowly. How can they migrate?
A
Dispersed by wind or animals
25
Natural obstacles to migration for animals
Mountain ranges
Seas
If animals cannot cross these they may become extinct
26
Human obstacles to migration for animals
Roads
Cities
If animals cannot cross these they may become extinct
27
How many people live in regions which are vulnerable to biome changing?
1 billion
28
2 positives of biome change
> Drilling for oil under Arctic Ocean is becoming possible w decrease in sea ice
> North-West Passage for ships between North Pole + North America could become a trade route
29
Tropical forest // what is it?
Hot and wet areas with broadleaved evergreen forest
30
Tropical forest // where is it?
Within 5 degrees North and South of equator
31
Tropical forest // climate + limiting factors
- high rainfall
- high temps (26-28 degrees)
- little seasonal variation
- high insolation as near equator
- rain washes nutrients out of soil (leaching_ so nutrients may be limiting plant growth
32
Tropical forest // what's there
- high levels biodiversity
- plants compete for light so grow tall to absorb it
- many niches + habitats for animals
- plants have shallow roots as most nutrients near surface so have buttress roots to support them
33
Tropical forest // net productivity
- produce 40% of NPP of terrestrial ecosystems
- growing season all year round
- fast rate of decomposition, respiration + photosynthesis
- large mature trees = use all glucose in respiration so no net gain
- young plants = huge growth rates + biomass gain
- rapid recycling of nutrients
34
Tropical forest // human activity
- 50%+ of world's pop. living in tropics + subtropics
| - Too many people exploiting forests + does not have type to recover (not sustainable)
35
Tropical forest // issues
- logging
- conversion to grazing
Tropical rainforests mainly in LEDCs + have been exploited for economic gain
36
Tropical forest // examples
Amazon rainforest
Congo in Africa
Borneo rainforest
37
Deserts // what is it
Dry areas
Usually hot in day
Cold at night (due to clear skies + little vegetation to insulate ground)
38
Deserts // distribution
Cover 20-30% of Earth's surface about 30 degrees North + South of Equator where dry air descends
Most are in middle of continents
39
Deserts // climate + limiting factors
Water is limiting
Precipitation less than 250mm per year
Evaporation exceeds precipitation
40
Deserts // what's there
- low biodiversity
- organisms that can survive are well-adapted
- soils rich in nutrients as not washed away
- plants are drought-resistant
- most succulents w adaptations to store water + reduce transpiration
- reptiles are dominant
- small animals are nocturnal or reduce water loss by having no sweat glands
41
Deserts // net productivity
- both primary + secondary low as water is limiting and plant biomass cannot build up to large amounts
- food chains short because of this
42
Deserts // human activity
- nomadic tribes herd animals e.g. goats as agriculture generally not possible
- low pop. density
- oil found under deserts in Gulf States
- deserts are rich in minerals (gold, silver_
- high rate of evaporation leading to salinisation
43
Deserts // issues
desertification - when an area becomes a desert through overgrazing, over cultivation, drought e.g. sahel
44
Deserts // examples
Sahara, Africa
| Gobi, China (cold desert)
45
Temperate grasslands // what
flat areas dominated by grasses and herbaceous plants
46
Temperate grasslands // where
in centres of continents 40-60 degrees North of Equator
47
Temperate grasslands // what's there
- grasses, wide variety
- no climax community as arrested by grazing animals
- grasses die back in winter but roots survive
- decomposed vegetation forms a mat, high levels of nutrients in this
- burrowing animals e.g rabbits
- carnivores e.g. wolves
- no trees
48
Temperate grasslands // climate + limiting factors
P = E
Temp. range high as not near sea to moderate temperatures
Clear skies
Low rainfall, threat of drought
49
Temperate grasslands // net productivity
not very high
50
Temperate grasslands // human activity
- used for cereal crops
- black earth soils of the steppes rich in organic matter+ deep so ideal for agriculture
- prairies in north america = less fertile so have to add fertiliser
51
Temperate grasslands // issues
- Dust Bowl in 1930s in America when overcropping + drought led to soil being blown away on Great Plains
- Desertification due to overgrazing
52
Temperate grasslands // examples
North American prairies
Pampas in Argentina
Russian steppes
53
Temperate forests // what is it
mild climate, deciduous forest
54
Temperate forests // where
40-60 degrees North + South of equator
55
Temperate forests // climate + limiting factors
P > E
Rainfall = 500 - 1500mm per year
Temp range = -30 to +30 degrees
56
Temperate forests // what's there
- relatively few species
- dominated by one species
- e.g. UK, oaks reach heights of 40m + are dominant species of the climax vegetation
- flowering plants eg bluebells bloom early in year before tall trees develop full foliage
- rapid recycling of nutrients but some lost through leaching, producing brown soil
57
Temperate forests // net productivity
- 2nd highest NPP after rainforests
- but much lower than rainforests due to leaf fall in winter so reduced photosynthesis
- temps. and insolation lower in winter
58
Temperate forests // human activity
- temperate forest cleared for agriculture // urban developments
- large predators (wolves, bears) virtually wiped out
59
Arctic tundra // what is it
cold, low precipitation
long, dark winters
permafrost present (frozen soil)
no trees
60
Arctic tundra // where
south of Arctic ice cap
| small amounts in Southern hemisphere
61
Arctic tundra // climate + limiting factors
> low temperatures so rates of respiration, photosynthesis + decomposition are low
> from May to August, the sun never sets, so ice melts quickly
> in spring + summer, animals are active + plants grow rapidly
> summer temps. can reach 30 degrees
62
Arctic tundra // what's there
- no trees
- low-growing plants (grasses, mosses)
- growing season = 8 weeks in summer
- animals = thick fur + small ears to reduce heat loss
- simple ecosystems w. few species
- soil poor, low inorganic matter + minerals
63
Arctic tundra // net productivity
- very low
| - slow decomposition so many peat bogs where most of carbon is stored
64
Arctic tundra // issues
- fragile ecosystems
- take long time to recover from disruption
- mining + oil extraction in Canada destroy tundra
- global warming decrease tundra's winter
- plants will die
- animal migrating patterns change
- large amounts of methane locked up in tundra ice, so if released...
65
Arctic tundra // examples
siberia
| alaska
66
Deep ocean // what is it
ocean
| seafloor beyond continental shelves
67
Deep ocean // where
65% of Earth's surface
| most is abyssal plain of the ocean floor
68
Deep ocean // climate + limiting factors
- pressure inc. w depth
- temp decrease to constant -2 at depth
- below 1000m there is no light
- low levels of nutrients + low primary productivity but some dead organic matter falls to deep ocean floors
69
Deep ocean // what's there TOP 200M
TOP 200M
- light for photosynthesis so phytoplankton + algae (main producers)
- eaten by zooplankton, fish, squid...
70
Deep ocean // what's there 200M-1000M
200M-1000M
- pressure inc. with depth so fish muscular to resist pressure
- many fish red so absorb shorter wavelengths of light that penetrate further
71
Deep ocean // what's there 1000M-4000M
1000M-4000M
- higher diversity, always dark
- fish are black
- create own light to hunt // avoid predators
72
Deep ocean // what's there 4000M TO BOTTOM
4000M TO BOTTOM
- huge pressures
- constant cold
- mostly shrimps, jellyfish
73
Deep ocean // what's there BOTTOM
BOTTOM
- fine sediments made up of debris from above
- when volcanoes erupt, chemosynthetic bacteria gain their energy from sulphur
74
Deep ocean // net productivity
low
75
Deep ocean // issues
pollution from run-off from rivers, sewage
| ocean warming due to climate change
76
What is zonation?
Zonation is the change in community along an environmental gradient due to changes in:
- altitude
- latitude
- tidal level
- distance from shore
77
What is succession?
Succession is the process of change over time in an ecosystem involving pioneers intermediate + climax communities
78
What is primary succession?
- Occurs on a bare inorganic surface
- It occurs as new land is either created or uncovered such as river deltas, after volcanic eruptions, on sand dunes
- Plants quickly start to colonise bare land + over time an entire plant community develops
- This change is directional as one community is replaced by another
79
What is the result of succession?
Succession results in a natural increase in complexity to the structure and species composition of a community over time
80
Stages in primary succession // 0. bare, inorganic surface
- lifeless abiotic environment becomes available for colonisation by pioneer plants + animals
- soil is nutrient poor w. erratic water supply
81
Stages in primary succession // 1. colonisation
- first species to colonise an area are called PIONEERS adapted to extreme conditions
- pioneers typically r-selected species w. small size, rapid growth + production of many offspring // seeds
82
Stages in primary succession // 2. establishment
- species diversity increases
- invertebrate species live in soil increase humus content + water-holding capacity
- weathering enriches soil w. nutrients
83
Stages in primary succession // 3. competition
- microclimate changes as new species colonise
- larger plants inc. cover + provide shelter, allowing K-selected species to live there
- temps, sun + wind less extreme
- earlier pioneer species unable to compete w. K-species for space, nutrients or light so lost from community
84
Stages in primary succession // 4. stabilisation
- fewer new species colonise
| - complex food webs develop
85
Stages in primary succession // 5. climax community
- final stage (climax community) is stable + self-perpetuating
- exists in a steady-state dynamic equilibrium
- climax represents maximum possible development that a community can reach under prevailing environmental conditions of temp, light + rainfall
86
What is a hydrosere?
A succession in water
87
How does succession in a lake work?
- continuous inputs of sediment from rivers
- some sediment passes through but a lot sinks to bottom
- as plant communities develop, they add dead, organic material to these sediments
- sediments build up allowing rooted plants to invade lake margins as lake fills in
- eventually leads to establishment of climax communities around lake margins
- in smaller lake // pond leads to disappearance of pond
88
What is secondary succession?
> Occurs on soils that are already developed & ready to accept seeds carried in by wind
> Often dormant seeds left in soil from previous community
> Shortens no. stages community goes through
89
6 changes that occur during a succession
- size of organisms increases w. trees creating more hospitable environment
- energy flow becomes more complex as simple food chains -> complex food webs
- soil depth, humus, mineral content + cycling increase
- biodiversity increases as more niches appear + then falls as climax comm. reached
- NPP and GPP rise and then fall
- Productivity : Respiration ratio falls
90
Succession on sand dunes // Studland Bay, Dorset
- bare surface sand
- pioneer plants low growing w. fat fleshy leaves to withstand being submersed
- later, predominant species = marram grass, has waxy leaves to reduce transpiration + silica in cell structures giving leaves flexibility
- sandy soil has developed supporting pasture grasses+bushes e.g. sea buckthorn w. nitrogen-fixing nodules to thrive in nutrient-poor soil
- scrub develops+shorter species shaded out
- oldest dunes have forest // pine + finally oak, ash (climatic climax vegetation)
91
As succession develops, what are there increases in?
```
Vegetation cover
Soil depth
Humus content
Soil acidity
Moisture content
Sand stability
```
92
How can successions be stopped or 'arrested'
By an abiotic factor e.g. waterlogging of soil
By a biotic factor e.g. heavy grazing
This results in a sub-climax community that will only continue its development if the limiting factor is removed
93
How are plagioclimax communities formed?
Natural event e.g. fire or landslide
Human activity e.g. agriculture
This results in plagioclimatic community such as pasture, arable farmland or plantations w. reduced biodiversity
94
What is the conflict between natural succession and humans requirements in agriculture?
Natural system leads to
- increasing complexity
- longer food chains
- higher biodiversity
Food production aims for
- simple system
- weed plants are controlled
- monoculture maximises yield
- doesn't reach climax community
95
6 features of K-strategists e.g. humans
- small no. offspring
- invest large amounts of time + energy into parental care
- most offspring survive
- good competitors
- pop. size close to carrying capacity
- in stable, climax ecosystems, K's outcompete Rs
96
7 features of R-strategists e.g. invertebrates
- use lots of energy in vast production eggs
- no energy used in raising them after hatching
- lay their eggs + leave them forever
- reproduce quickly
- able to colonise new habitats rapidly
- due to fast growth rates, may exceed carrying capacity w. population crash as result
