biomes

Chapter 39: Biomes

  • List of Biomes

    • Tundra

    • Taiga

    • Desert

    • Chaparral

    • Grassland

    • Tropical Savanna

    • Tropical Rainforest

    • Temperate Deciduous Forest

    • Temperate Evergreen Forest

    • Mountain Zones

    • Polar Ice

Learning Objectives (Chapter 39, Sections 39.1 – 39.3)

  1. Explain the major climate patterns found on the planet.

  2. Identify the geographical location of terrestrial biomes.

  3. Describe the main characteristics of the terrestrial biomes, including:

    • Tropical rainforests

    • Temperate forests

    • Taiga

    • Tundra

    • Tropical savanna

    • Temperate grassland

    • Desert

    • Mediterranean shrubland

    • Polar ice

Definition of Biomes

  • A biome is defined as a major type of ecosystem that is characterized by a specific climate and species composition.

  • Reference: Section 39.1, Figure 37.1

Climate vs. Weather

  • Weather: The conditions of the atmosphere over a short period of time.

  • Climate: How the atmosphere behaves over a long period of time and space.

    • Characteristics:

      • Can change within minutes or hours (weather).

      • Average regional weather pattern observed over decades (climate).

Example of Weather vs. Climate

  • Average temperatures throughout the year (30-year normal average):

    • Demonstrated via a temperature graph showing seasonal variability for January through December.

Characteristics of Climate

  • Important characteristics used to define climate include temperature and rainfall.

    • Example:

      • Spring: cool and rainy

      • Summer: hot and humid

Primary Producers in Biomes

  • Primary producers include organisms like plants and phytoplankton, which produce the food that sustains other organisms in the biome.

  • Reference: Section 39.1, Figure 39.1

Abiotic Factors Influencing Species Composition

  • Abiotic factors that significantly impact ecosystems include:

    • Light

    • Moisture

    • Temperature

    • Nutrient availability

    • Oxygen availability

    • Salinity

    • Fire

  • Important to understand how these factors affect primary producers, subsequently impacting the entire food web.

Ecosystem Diversity

  • Variations in climate result in different ecosystems across the Earth.

  • Reference: MODIS Oceans Group, NASA Goddard Space Flight Center, Section 39.2, Figure 39.3

Influence of Seasonality on Climate

  • The tilt of the Earth causes different seasons, which are opposite in the two hemispheres.

    • Near the equator, the sun's position explains long days and warm temperatures year-round.

    • Conversely, poles experience short days and colder temperatures year-round.

  • Reference: Section 39.2, Figure 39.2

Air Circulation Patterns

  • Air circulation influences climate by determining moisture levels in various regions.

    • Warm water evaporates near the equator, rises, forms clouds, and precipitates over tropical areas.

    • Dry air descends around 30 degrees latitude, leading to desert formation.

  • Reference: Section 39.2, Figure 39.4

Midlatitudes vs. Polar Latitudes

  • Near 60 degrees latitude: Warm air rises, releasing precipitation over midlatitudes (temperate biomes).

    • Cold, dry air remains over polar biomes.

  • Reference: Section 39.2, Figure 39.4

Impact of Ocean Currents on Climate

  • Ocean currents, both warm and cool, significantly impact coastal climates.

    • Example: Cold water currents along the west coast of North America vs. warmer currents on the east coast.

  • Reference: Section 39.2, Figure 39.5

Effect of Mountains on Climate

  • Mountains influence surrounding climates in two key ways:

    1. Higher elevations are cooler, impacting temperature.

    2. Mountains block winds, causing one side to be wet and the opposite side (rain shadow) to be dry.

  • Reference: Section 39.2, Figure 39.6

Characteristics of Terrestrial Biomes

  • Terrestrial biomes possess distinctive communities.

    • Temperature and moisture are crucial in determining the dominant plant species.

    • Vegetation influences the biodiversity of organisms within each biome.

  • Reference: Section 39.3, Figure 39.8

Descriptions of Major Terrestrial Biomes

Tropical Rainforest

  • Characterized as warm and wet with the highest species diversity of all terrestrial biomes.

    • Current threats include global deforestation, affecting water and carbon cycles.

    • Reference: Section 39.3, Figures 39.8, 39.9

Temperate Forests

  • Features warm summers, cool winters, and consistent rainfall.

  • Common flora: deciduous trees that shed leaves in autumn and coniferous evergreens.

    • Geographical range: large areas between 30 and 60 degrees North latitude.

  • Reference: Section 39.3

Taiga (Boreal Forest)

  • Environment is cold with relatively dry conditions.

    • Characterized by long, harsh winters lasting over six months, resulting in a short growing season.

    • Limited moisture in winter months as water may be frozen.

    • Flora mainly consists of evergreen trees, with only a few species of mammals and birds staying year-round.

    • Reference: Section 39.3, Figures 39.8, 39.11

Tundra

  • Defined by very cold temperatures and minimal moisture.

    • Animals possess thick fur due to extreme cold.

    • Features a frozen layer (permafrost) beneath the topsoil that restricts vegetation to small plant species.

    • Reference: Section 39.3, Figures 39.8, 39.11

Polar Ice

  • A biome characterized by extreme cold, dryness, and winds throughout the year.

    • Features distinct differences between the Arctic and Antarctic regions.

    • Arctic: a thin ice layer covering the Arctic Ocean.

    • Antarctic: a substantial landmass covered by thick ice.

    • Both polar regions exhibit interactions with water, possessing characteristics of both terrestrial and aquatic biomes.

    • Phytoplankton serve as the primary producers in this biome.

    • Reference: Section 39.3, Figure 39.17

Tropical Savanna

  • Describes a warm environment with distinct wet and dry seasons.

    • Characterized by sparse trees and shrubs, with a dominance of perennial grasses and drought-resistant flora (palms, acacias).

    • Commonly inhabited by herds of grazing animals which play a significant role in this ecosystem.

    • Fire plays a crucial role in maintaining savanna health by promoting the growth of fire-adapted flora, preventing overgrowth, and aiding nutrient cycling.

    • Reference: Section 39.3, Figures 39.8, 39.12

Temperate Grassland

  • Exhibits a moderately moist climate characterized by hot summers and cold winters.

  • Vegetative landscape predominantly features wind-pollinated grasses, with minimal tree presence.

    • Large herbivorous grazers are common within these ecosystems.

    • Reference: Section 39.3, Figures 39.8, 39.13

Desert

  • Both cold and hot deserts share a common trait of being arid, receiving less than 20 ext{ cm} of precipitation annually.

  • Typically located at 30^{ ext{°}} North and South latitudes or in rain shadows of high mountains.

    • Soil types are low in organic content.

    • Flora adapted to water storage, with a prevalence of nocturnal animals.

    • Reference: Section 39.3, Figures 39.8, 39.14

  • Examples of desert flora and fauna:

    • Fennec fox

    • Desert beetle

    • Lappet-faced vulture

    • Cacti

    • Various shrubs and grasses

Mediterranean Shrubland (Chaparral)

  • Characterized by hot, dry summers and cool, moist winters, making it prone to fire during the summer months due to low humidity.

    • Vegetation is comprised of fire-resistant, drought-tolerant plants.

    • Common fauna includes jack rabbits, mule deer, and coyotes.

    • Reference: Section 39.3, Figures 39.8, 39.15