Biomes of North America

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Questions and Answers

What is a characteristic of urban ecosystems?

They are typically devoid of alien species.

They are isolated from other ecosystems.

They can support diverse species due to human influence. (correct)

They often have low biodiversity.

What impact do modern agricultural practices have on ecosystems?

They create stable ecosystems with high resilience.

They generally increase species diversity.

They can lead to unstable ecosystems with low diversity. (correct)

They promote ancient farming techniques.

How do rural ecosystems often influence the landscape?

They are linked with industrial facilities and natural resource harvesting. (correct)

They primarily consist of untouched wilderness.

They feature extensive natural growth unaffected by human activities.

They are characterized by minimal human infrastructure.

Which type of ecosystem is defined as being built primarily by animals?

Coral reefs Signup and view all the answers

What is a significant feature of agroecosystems?

They often rely on high-intensity farming methods. Signup and view all the answers

Which characteristic is typical of temperate zones' biodiversity?

Diversity influenced by climate and ecosystem types. Signup and view all the answers

What is one reason for leaf coloration changes in the fall?

Breakdown of chlorophyll revealing other pigments. Signup and view all the answers

Which of the following is a defining feature of boreal forests?

Dominance of coniferous trees. Signup and view all the answers

Which characteristic is NOT typically associated with temperate rainforests?

Extreme cold temperatures Signup and view all the answers

What environmental factor primarily limits tree growth in chaparral biomes?

Fires Signup and view all the answers

In what type of ecosystem would you find high productivity and biomass alongside complex vertical structures?

Evergreen tropical rainforest Signup and view all the answers

Which adaptation is common for plants in desert ecosystems to cope with arid climates?

Storing water deep in their roots Signup and view all the answers

What role do large herbivores play in the tropical savanna ecosystem?

Limit tree growth Signup and view all the answers

Which factor contributes to the diurnal temperature fluctuations in evergreen tropical rainforests?

Lack of frost Signup and view all the answers

What is a significant characteristic of the temperate grassland biome?

Cold winters and hot summers Signup and view all the answers

Which type of vegetation is likely to dominate in a typical chaparral climate?

Shrubs Signup and view all the answers

What causes fall foliage color changes in temperate zones?

Reduction of chlorophyll leading to natural pigments revealing Signup and view all the answers

Which of the following biomes experiences the lowest annual precipitation?

Desert Signup and view all the answers

What is a common characteristic of the tundra ecosystem?

Short growing season that prevents tree growth Signup and view all the answers

Which of the following is true about boreal forests?

They are dominated by coniferous trees. Signup and view all the answers

What is the expected effect of seasonality on biodiversity in temperate zones?

Seasonality generally reduces species richness. Signup and view all the answers

Which pigment in leaves is responsible for red coloration during fall?

Anthocyanins Signup and view all the answers

What adaptive hypothesis explains why red pigments appear in fall foliage?

They act as a warning signal to migrating insects. Signup and view all the answers

Which of the following statements about temperate rainforests is TRUE?

They are characterized by coniferous and deciduous trees. Signup and view all the answers

What environmental factor primarily defines the characteristics of biomes?

Climate Signup and view all the answers

Why do deserts typically occur around 30°N and 30°S latitude?

Dry air returns to the Earth's surface Signup and view all the answers

Small shrubs and grasses are characteristic of which biome?

Tundra Signup and view all the answers

What does the term 'evapotranspiration' refer to in the context of the tundra?

The combined loss of water from soil and plant surfaces Signup and view all the answers

Which animal is considered a dominant large herbivore in the arctic tundra?

Caribou Signup and view all the answers

Which factor is NOT typically a classification criterion for biomes?

Soil type Signup and view all the answers

In temperate grasslands, which type of vegetation is most commonly found?

Grasses and herbaceous plants Signup and view all the answers

What event triggers the production of anthocyanins in leaves during autumn?

Breakdown of chlorophyll Signup and view all the answers

Which biome is known for having consistently low temperatures and low precipitation year-round?

Tundra Signup and view all the answers

Study Notes

Temperate Rainforest

Found in western North America
Receives 2m of rainfall per year
Contains the highest conifer diversity of all biomes
Trees can reach enormous girth and height
Abundant moss can be found

Temperate Grasslands

Also known as prairies and steppes
Low annual precipitation
Cold winters, hot summers
Insufficient moisture to support forests
Fire and herbivores keep trees out of the more humid regions such as tallgrass prairies

Chaparral

Mild, moist winters and hot, dry summers
“Mediterranean climate”
Poor soils and fires limit tree growth
Dominant plants are shrubs
Found in California, South Coast of France and other similar regions

Deserts

Too dry for closed vegetation, exposed soil exists
Occur in tropical, temperate, and arctic climates
Plants have adapted strategies to tolerate arid climates:
- Storing water in deep roots (succulents)
- Avoiding dry periods (annuals)
- Having deep roots
- CAM photosynthesis (grabbing CO2 during the night, closing stomata during the day)
Examples:
- Sahara Desert
- Mojave Desert
- Atacama Desert

Tropical Savanna and Dry Forest

Tropical climate with a dry season
Long drought: Savanna (grassland) with scattered trees. Fire and herbivores limit tree growth.
Short drought: Dry forests with deciduous trees

Evergreen Tropical Rainforest

Close to the equator
No dry season
No frost
Diurnal temperature fluctuations are larger than seasonal fluctuations
Often daily precipitation occurs
High productivity and biomass
Complex vertical structure
Trees send out large roots to support themselves

Lentic Ecosystems

Lakes and ponds with standing (non-flowing) water
Ecological variation is complex
Ecologists classify schemes that aggregate ecological variation into clusters with general similarity of structure and function

Biomes

Clusters of ecosystems with a general similarity of structure and function
Exist over an extensive geographical range, occurring anywhere in the world with suitable environmental conditions
Defined by late-successional vegetation and characteristic animals
Defined by climate
Key characteristic is the morphological and physiological traits of dominant organisms (plants and animals)

Terrestrial Biomes

Defined by their dominant organisms
Found all over the world
Global distribution of terrestrial biomes is driven by climate

Climate

Earth’s axis of rotation is tilted at 23° relative to the plane of our orbit around the sun
This tilt gives rise to seasonality and variation in temperature and precipitation

Equator

Has 12 hours of sunlight and 12 hours of darkness
Annual variation in day length corresponds with distance from the equator

Convective Currents

Warm air at the equator rises, cools, water condenses, and rains, creating a cycle:
- Warm air at the equator rises --> cools --> water condenses --> rains
- Cool, dry air eventually returns to the planet surface at about 30°N and 30°S
Drier air returning to the surface at 30°N and 30°S creates deserts due to cooler, drier air

Tundra

High latitude biome
Growing season too short to support trees
Low precipitation, low evapotranspiration
Permafrost prevents drainage
Dominant organisms:
- Small shrubs, grasses, and sedges
- Migratory caribou (large herbivore)
Biodiversity is generally low, but many migratory birds breed in the arctic
Example: Arctic Terns breeding in the Arctic, then moving to the Antarctic

Temperate Zones

Lie between the Arctic/Antarctic and Tropics of Cancer/Capricorn
Variable vegetation depending on latitude and patterns of precipitation
Marked seasonal variation is common

Boreal Forest (Taiga)

Dominated by coniferous trees
Spread across the northern hemisphere
Short but warm summers, long cold winters
Supports sustained growth
After events such as fire, deciduous trees like aspen and birch may grow

Temperate Deciduous Forest

Cold short winters and warm, long summers
Supports many deciduous trees
In Canada, highest tree diversity is in southern Carolinean forests
High species richness in southern forests

Fall Leaf Coloration

Yellow and orange colors in fall leaves are carotenoids (unmasked by the breakdown of chlorophyll)
Red colors are anthocyanins (newly produced by the tree)
Fall colours are not a product of leaf senescence, but produced as a protection mechanism

Adaptive hypotheses for fall leaf coloration

Photoprotection hypothesis: Red pigments protect against harmful effects of light at low temperatures
Coevolution hypothesis: Red is a warning signal toward insects migrating to trees in autumn

Seashores

Ecology determined by bottom characteristics
Seashores have a huge diversity in ecosystems

Estuaries

Regions at the interface of marine/freshwater
Productive regions
Examples:
- Amazon River
- Nile River

Coral Reefs

Ecosystems built by animals
Only found close to the equator
Need access to sunlight for photosynthesis

Anthropogenic Ecosystems

Ecological characteristics convergent in different climate zones
Can be centuries old
Often with adapted organisms
Three clusters: Urban, Rural, and Agroecosystems

Urban Ecosystems

Relatively high biodiversity due to heterogeneity, warm microclimate, and species introductions through humans
Many species are alien, and do not survive without human influence

Rural Ecosystems

Extensive networks of highways, railroads, electrical lines, industrial facilities, and towns associated with the harvest and processing of natural resources

Agroecosystems

Modern agricultural practices can lead to unstable ecosystems with low diversity
Centuries-old low-intensity agricultural practices may result in high species diversity

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Description

Explore the diverse biomes of North America, including temperate rainforests, grasslands, chaparral, and deserts. Each biome has unique characteristics, climate, and flora, often adapted to their specific environments. Test your knowledge on how these ecosystems differ and the plants that inhabit them.