Communities and Biomes

Communities and Biomes

Community • Community: A collection of several interacting populations that inhabit a common environment.

Limiting Factors – Factors that affect an organism’s ability to survive in its environment, such as the availability of water and food, predators, and temperature, are called limiting factors.

• A limiting factor is any biotic or abiotic factor that restricts the existence, numbers, reproduction, or disturbance of organisms.

Ranges of Tolerance • The ability of an organism to withstand fluctuations in biotic and abiotic environmental factors is known as tolerance

Ecological Succession • Ecosystems are constantly changing in response to natural and human disturbances. • As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community.

Ecological Succession • Ecological succession is the series of predictable changes that occur in a community over time. – Primary succession takes place on bare rock surfaces where no soil exists. Pioneer species are the first species to live in these areas. – Secondary succession occurs when a disturbance changes a community without removing soil.

Primary Succession

Secondary Succession

Biotic and Abiotic Factors • Organisms in ecosystems are affected by both biotic and abiotic factors. • Biotic factors are all of the living things with which organisms interact. • Abiotic factors are nonliving, physical things. (Ex. temperature and soil type) • Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which and organism lives.

Abiotic and Biotic Factors

Abiotic Factors Biotic Factors

ECOSYSTEM

Ecological Succession Video • http://www.youtube.com/watch?v=V49IovRSJ Ds

Climate • In the atmosphere, temperature, precipitation, and other environmental factors combine to produce weather and climate. • Weather: is the day-to-day condition of Earth’s atmosphere at a certain time and place. • Climate: is the average yearly condition of temperature and precipitation in a region. • Climate affects ecosystems.

The Greenhouse Effect • Carbon dioxide and other atmospheric gases trap heat energy and maintain Earth’s temperature range. • These gases function like the glass windows of a greenhouse.

• The trapping of heat by gases in the atmosphere is called the greenhouse effect. • This greenhouse effect helps temperatures on Earth stay within a range that supports life.

The Greenhouse Effect

The Effect of Latitude on Climate

• Latitude also affects climate. Earth has 3 main climate zones: polar, temperate, and tropical. – Polar Zones are cold areas where the sun’s rays strike Earth at a very long angle. – Temperate Zones sit between the polar zones and the tropics. The climate in these zones ranges from hot to cold, depending on the season. – The Tropical Zones or tropics, is near the equator. The climate here is almost always warm.

The Effect of Latitude on Climate

90°N North Pole

Sunlight

66.5°N

Arctic circle

Sunlight

Tropic of Cancer

Most direct sunlight

Equator

0°

Tropic of Capricorn

Sunlight Arctic circle

Sunlight

23.5°N

66.5°S

90°S South Pole

23.5°S

Heat Transport in the Biosphere • Unequal heating of Earth’s surface also causes winds and ocean currents. • Wind and ocean currents move heat through the biosphere.

Biomes

• A biome is a group of land communities that covers a large area and has a certain soil type and climate • Within a biome, there maybe microclimates • A microclimate is a small area where the climate differs from that of the surrounding area.

The Major Biomes • There are ten major biomes: – Tropical Rain Forest, Tropical Dry Forest, Tropical Savanna – Desert – Temperate Grassland, Temperate Woodland and Shrubland, Temperate Forest – Northwestern Coniferous Forest, Boreal Forest (or Taiga) – Tundra • Each biome has its own set of abiotic factors and a typical collection of organisms. • Some areas, such as mountains and polar ice caps, do not fall neatly into the major biomes

Compare/Contrast Table of Biomes

Ten Major Biomes Biome

Precipitation

Temperature

Soil

Diversity

Trees

Grasses

Tropical Rain Forest

high

hot

poor

high

dense

sparse

Tropical Dry Forest

variable

mild

rich

moderate

medium

medium

Tropical Savanna variable Desert low Temperate Grassland moderate

mild variable summer hot

clay poor rich

moderate moderate moderate

sparse sparse absent

dense sparse dense

Temperate woodland and Shrubland

summer low, winter moderate

summer hot

poor

low

medium

medium

Temperate Forest

moderate

summer moderate, rich winter cold

high

dense

sparse

Northwestern Coniferous Forest Boreal Forest

high

rocky, acidic

low

dense

sparse

poor, acidic

moderate

dense

sparse

Tundra

low

summer mild, winter cold summer mild, winter cool summer mild, winter cold

poor

low

absent

medium

moderate

The World’s Major Land Biomes

Tropical rain forest

Temperate grassland

Temperate forest

Tundra

Tropical dry forest

Desert

Mountains and ice caps

Tropical savanna

Temperate woodland and shrubland

Northwestern coniferous forest Boreal forest (Taiga)

Aquatic Biomes

• Unlike land biomes, which are grouped geographically, aquatic biomes are grouped by the abiotic factors that affect them. • Aquatic biomes are described mainly by the depth, flow, temperature, and chemistry of their water.

Aquatic Energy • In many aquatic biomes, tiny free-floating swimming organisms can be found. These organisms are called plankton. • There are 2 types of plankton (phytoplankton and zooplankton) – Phytoplankton are single-celled algae that use nutrients in water to make food. They form the base of many aquatic food webs. – Zooplankton are animals that feed on phytoplankton

Aquatic Biomes • There are 3 main groups of aquatic biomes: • 1. Freshwater biomes can be divided into several types. – Flowing-water biomes (rivers and streams) flow over land. – Standing-water biomes include lakes and ponds – Freshwater wetlands include bogs, marshes, and swamps. In wetlands, water covers the soil or is present at or near the surface for at least part of year.

Bogs, Marshes, and Swamps

Aquatic Biomes

2. Estuaries are wetlands formed where rivers meet the sea. They contain a mixture of fresh and salt water. Most food made in estuaries enters food webs as tiny pieces of organic matter, called detritus. – Salt marshes are temperate estuaries. Salt-tolerant grasses and sea grasses are the dominant plant life in salt marshes. – Mangrove swamps are tropical estuaries. The dominant plant life in mangrove swamps includes several species of salt-tolerant trees, called mangroves, and sea grasses.

Aquatic Biomes

3. Marine biomes exist in the ocean. The ocean is divided into zones based on how much light penetrates the water. – The photic zone is the well-lit upper layer of water. Photosynthesis can take place here. – The aphotic zone is the permanently dark lower layer of water. Producers here use chemosynthesis to make food.

Oceans • The ocean is also divided into zones based on depth and distance from shore: the intertidal zone, the coastal ocean, and the open ocean, and benthic zone.

Marine Biomes Organisms in the intertidal zone are exposed to regular and extreme changes in their surroundings. (tides)

The coastal zone is relatively shallow, lies entirely within the photic zone, and is often rich in plankton and other organisms. Coral reefs grow in tropical coastal oceans.

Marine Biomes The open ocean is the largest zone, covering more than 90 percent of the surface area of the world’s oceans. These areas typically have low levels of nutrients and support only small producers.

Benthic zone is the bottom of the ocean, contains organisms that live attached to or near the bottom.

Zones of a Marine Biomes land Coastal ocean Open ocean

200m 1000m

Photic zone

4000m

Aphotic zone

6000m

Ocean trench Continental shelf

Continental slope and continental rise

Abyssal plain

10,000m