2.4A Biomes, Zonation and succession Flashcards
What is the definition of a “biome”?
“A collection of ecosystems sharing similar climatic conditions”
What is the definition of “climate”?
“long term average weather, typically averaged over a period of 30 years”
What are the 5 major classes of biomes?
- Aquatic (Sometimes split into freshwater and marine)
- Forest (tropical temperate and boreal)
- Grassland (tropical or savanna and temperate)
- Desert (hot and cold)
- Tundra (arctic and alpine)
What are the 3 main factors affecting the distribution of biomes?
- Insolation
- Precipitation
- Temperature
What is “Insolation”?
Amount of solar radiation (energy from sun) reaching the Earth’s surface
(Measured by solar energy received per square cm per minute)
What is “Precipitation”?
Rain, snow, sleet, or hail that falls to, or condenses on, the ground
(Measure in mm per metre square)
What is “Temperature”?
Land and water absorb and retain heat differently
(Measured in degrees celsius)
What are factors affecting temperature?
- Latitude
- Season determined by earth’s tilt
What are “climographs”?
Graphs where both temperature and precipitation are represented.
Do biomes have boundaries?
Biomes are NOT uniform. They do NOT have defined boundaries and are NOT limited by national borders.
What are some facts about “temperate deciduous forests”?
Location: Between 40 and 60 degrees North and South of the equator
Climate: High rainfall (500-1500mm per year), Winter temperatures cool (above 0 degrees), summer temperatures between 20 and 25 degrees
Productivity: Relatively high, due to large dense and layered vegetation
Limiting factors: Lower layers have limited sunlight, low productivity during winter
Nutrient cycle: Relatively well balanced, no store holds the majority of nutrients
What are some facts about the “Australian Savanna (Tropical grassland)”?
Location: Found between 10 and 20 degrees south of the equator
Climate: Two seasons:
- Hot and Wet: Nov-April (High temperatures, 30-40, approx 800mm rain)
- Warm and Dry: May-Oct (Temperatures around low 30’s, 50mm rain)
Productivity: Low productivity, very little biomass
Limiting factors: Soils is poor and lacks nutrients, rainfall only occurs for half the year (little moisture)
Nutrient cycle: Complicated due to seasonal variations
What are some facts about the “Sahara (Desert Biome)”?
Climate: Minimal rainfall (less than 100mm per year), High mean daily temperatures (38 degrees)
Productivity: Very low productivity due to a lack of water (most rain evaporates before the plant can use it)
Limiting factors: Nearly every single resource is limited, high temperatures which only few plants can tolerate
Nutrient cycle: Nutrient stores and flows are so small some argue that the nutrient cycle isn’t even applicable
What is the definition of “zonation”?
“Zonation refers to changes in a community in response to a change, over a distance, in some environmental factors.”
Which diagrams are used to show zonation?
Kite diagrams are used to show zonation along a transect (a line across a habitat).
The number of organisms of each species are counted and recorded at regular intervals along the transect.
Kite diagrams are a chart that shows the number of species against distance along a transect, represented by the width of the kite shape.
What is the definition of “succession”?
“The orderly process of change over time in a community”
–> Changes in community of organisms frequently cause changes in the physical environment that allow another community to become established and replace the former through competition
What is “primary” succession?
- Succession occurring on a previously uncolonized substrate (no plants have grown there before)
(Starts from bare rock, bare sand, or water, and is VERY unusual today)
What is “secondary succession”?
- This time there are already soil and probably seeds present.
- This means the succession will happen more rapidly than primary succession.
- Wind blown plants that are tolerant to high levels of sun and grow fast called pioneer species will colonise the area.
What kind of population curve relates to “K” reproductive strategies?
S - Shape curve
What kind of population curve relates to “r” reproductive strategies?
J - Shape curve:
What are survivorship curves?
“Survivorship curves are geographical representations of the number of individuals in a population that can be expected to survive to any specific age.”
What are some characteristics of Type 1 species on the survivorship curve?
- High survival rate of the young, and low death rates.
- Increase among older age groups as they live our most of their expected life span
- -> K strategist species
What are some characteristics of Type 2 species on the survivorship curve?
- Relatively constant death rate
- Could be due to hunting or diseases
What are some characteristics of Type 3 species on the survivorship curve?
- Species that have many young, of which most die very quickly
- Higher death rates for the young, slower death rate for survivors
- -> r strategist species
