Kerry Song
Chapter 52 – An Introduction to Ecology and the Biosphere
Vocabulary:
- abiotic: Nonliving; referring to the physical and chemical properties of an environment.
- abyssal zone: The part of the ocean’s benthic zone between 2,00 and 6,000 m deep.
- aphotic zone: The part of an ocean or lake beneath the photic zone, where light does no
penetrate sufficiently for photosynthesis to occur.
- benthic zone: The bottom surface of an aquatic environment.
- benthos: The communities of organisms living in the benthic zone of an aquatic biome.
- biome: Any of the world’s major ecosystem types, often classified according to the
predominant vegetation for terrestrial biomes and the physical environment for aquatic
biomes and characterized by adaptations of organisms to that particular environment.
- biotic: Pertaining to the living factors – the organisms – in an environment.
- canopy: The uppermost layer of vegetation in a terrestrial biome.
- climograph: A plot of the temperature and precipitation in a particular region.
- detritus: Dead organic matter.
- disturbance: A natural or human-caused event that changes a biological community and
usually removes organisms from it. Disturbances, such as fires and storms, play a pivotal
role in structuring many communities.
- ecology: The study of how organisms interact with each other and their environment.
- ecotone: The transition from one type of habitat or ecosystem to another, such as the
transition from a forest to a grassland.
- pelagic zone: The open water component of aquatic biomes.
- photic zone: The narrow top layer of an ocean or lake, where light penetrates
sufficiently for photosynthesis to occur.
- thermocline: A narrow stratum of abrupt temperature change in the ocean and in many
temperate-zone lakes.
- turnover: The mixing of waters as a result of changing water-temperature profiles in a
lake.
Chapter Notes:
- ecology is scientific study of interactions between organisms and the environment
- ecological interactions occur at a hierarchy of scales
- ecology’s roots are basis to basic human interest in observing other organisms
- modern ecology is rigorous experimental science that involves observation and
breadth of biological knowledge
- ecologists generate hypotheses, manipulate environmental variables, and observe
outcomes
Concept 52.2 – The structure and distribution of terrestrial biomes are
controlled by climate and disturbance
- biomes are major life zones characterized by vegetation type/physical environment
- climograph helps highlight importance of climate on the distribution of biome, is a plot
of annual mean temperature/precipitation in particular region
- many factors play role in determining where biomes exist (e.g. abiotic characteristics:
bedrock, mineral nutrient availability, and soil structure can determine kind of
vegetation)
-climograph is based on annual averages
- pattern of climatic variation is as important as average climate
- most terrestrial biomes a named after major physical/climatic features for pre-dominant
vegetation
- biome is characterized by microorganisms, fungi, and animals adapted to
particular environment
- temperate grasslands are more likely than temperate forests to contain large grazing
mammals and have arbuscular mycorrhizal fungi
- ecotone is the area of intergradations that shows distinct boundaries between terrestrials
biomes that usually grade into each other without sharp boundaries
- vertical layering is important feature of terrestrial biomes; most forest have an upper
canopy
- provides different habitats for animals
- biomes are dynamic and is often disturbed
- disturbance is an event such as storm, fire, human, activity that changes
community, removing organisms from it, and altering resource availability
- biomes often exhibit extensive patchiness, w/different communities represented in
single area because of disturbances
- some biomes depend on periodic disturbances, such as natural wildfires
Concept 52.3 – Aquatic biomes are diverse and dynamic systems that cover
most of Earth
- aquatic biomes are characterized by primarily their physical environment; show less
latitudinal variation
- ecologists distinguish between freshwater and marine biomes on basis of physical and
chemical differences
- Marine biomes have salt concentration that average 3%; freshwater biomes are usually
characterized by salt concentration less than 0.1%
- oceans are largest marine biome; covers 75% of Earth’s surface; greatly impacts
biosphere; water evaporation from ocean provides most of Earth’s rainfall; ocean temp
affects global climate and wind patterns
- freshwater biomes are influenced by patterns and speed of water flow and climate
- aquatic biomes are physically and chemically stratified vertically and horizontally
- light is absorbed, intensity decreases rapidly with depth
- photic zone = sufficient light for photosynthesis, aphotic zone = little light penetrates;
together create the pelagic zone
- abyssal zone lies deep in the aphotic zone
- benthic zone is the bottom of all aquatic biomes, made up of benthos which is a
community of organisms collectively
- detritus is major food source for benthic species, which is also dead organic matter
- thermocline is a narrow layer of abrupt temperature change
- turnover sends oxygenated water from a lake’s surface to the bottoms and brings
nutrient-rich water from bottom to surface
- communities in freshwater and marine are distributed according to water depth, degree
of light penetration, distance from shore, and whether they a found in open or near
bottom of water
Concept Check:
Concept Check 52.2
1. Based on the climograph in Figure 52.10, what mainly differentiates temperate
grassland from temperate broadleaf forest?
Even though both biomes have the same range of temperature, the Temperate grassland
has less annual mean precipitation while the Temperate broadleaf forest has more annual
mean precipitation.
2. Identify the natural biome in which you live, and summarize its abiotic and biotic
characteristics. Do these reflect your actual surroundings? Explain.
The natural biome in which I live in is Desert. It is seasonally dry and hot and is
dominated by low scattered vegetation. There are a lot of shrubs. There are also many
snakes, lizards, ants, etc.
3. What If?: If global warming increases average temperatures on Earth by 4°C in this
century, predict which biome is most likely to replace tundra in some locations as a result
Northern Coniferous forests would replace tundra because a warmer climate will allow
more plants and trees to grow more easily
Concept Check 52.3
1. Why are phytoplankton, and not benthic algae or rooted aquatic plants, the dominant
photosynthetic organisms of the oceanic pelagic zone?
Phytoplankton are the dominant photosynthetic organisms of the oceanic pelagic zone
because benthic algae/rooted aquatic plants only occur in the photic zone.
2. Make Connections: Many organisms living in estuaries experience freshwater and
saltwater conditions each day with the rising and falling of tides. Based on what you
learned in Concept 44.1, explain how these changing condition challenge the survival of
these organisms.
These changing conditions challenge the survival of these organisms by making them
adapt to gain and lose water.
3. What If?: Water leaving a reservoir behind a dam is often taken from deep layers of the
reservoir. Would you expect fish found in a river below a dam in summer to be species
that prefer colder or warmer water than fish found in an undammed river? Explain.
I would expect fish found in a river below a dam in summer to be species that prefer
colder water because if the water is taken from deep layers, it is always more cold.
Test Your Understanding:
Test Your Understanding: Chapter 52
1. D
2. B
3. D
4. E
5. D
6. D
7. C
8. A
9. A
10. C
Lecture Notes: