Unit 4 Biomes& CommunitiesClimate, Biomes, and Community Interactions

What is the biggest influence on the

distribution of organisms?Climate!

How do we define climate?What factors determine the overall climate?

Sunlight and temperature relationship to currents and wind

Imagine Earth rotating – the land closer to the equator moves faster than that at the poles (deflecting the winds from a vertical pattern).

Sunlight - Seasonal Variation

Large Bodies of Water

MountainsWindward vs Leeward Side

climate’s impact on populations

Earth has warmed an average of 0.8°C since 1900 (campbell – bio)Predicted to warm 1 – 6 ° C by 2100Can seeds disperse quickly enough to sustain the range shift of each species as climate changes?

Checkpoint (campbell –bio)

Explain how the sun’s unequal heating of Earth’s surface leads to the development of deserts around the 30° north and south of the equator. Given the following two microclimates in the same region, describe some differences.

unplanted agricultural field vs. nearby stream with lots of trees

BiomesThe biosphere encompasses all living things on Earth.

It comprises a number of aquatic (freshwater biomes vs. marine) and terrestrial biomes (tropical, dessert, temperate, grassland.)

Biomes within the same category have specific, characteristic features, but can range in biodiversity.

Ocean biome

Desert biome

Aquatic BiomesCover 75% of Earth’s surface!! Less than1% of that is freshwater.

FRESHWATER BIOMES ( lakes, ponds, rivers, wetlands)

Wetlands: transitional biome b/w aquatic and terrestial – such as marshes, bogs, swamps

MARINE BIOMES ( ocean, coral reefs, estuaries)Estuary - another transition area b/w a river and the ocean

Terrestrial BiomesTerrestrial biomes are recognized for all the major climatic regions of the world and are classified on the basis of their predominant vegetation type. The same biome may occur in widely separated regions.

Your task …1. You will be assigned two biomes.2. Complete a climograph (a plot of the

annual mean temp and rainfall) for each on the SAME graph.

Tropical Rainforests

PrecipitationPlants:Animals

Distribution:

The climate is warm and rainy all year round.

Temperature range: 2.2°CAnnual total rainfall: 262 cm

Example: Iquitos, Peru 3°S

Physical Factors in Tropical Rainforests

Desert

PrecipitationPlants:Animals

Distribution:

The climate is

Hot DesertsDeserts are arid regions (annual rainfall generally less than 25 cm). The hot desert biome is found in two belts, centered at 30° latitude north and south of the Equator.Hot deserts receive most of their rainfall in summer. The driest regions are in central Australia and the middle of the Sahara Desert.

The temperature range is approximately 30°C, and the winter and summer are both very warm.

Sahara DesertRainbow Valley, central Australia

Hot Desert CommunitiesDominant plants

Succulent plants such as cacti; many different growth forms.

Floral richnessRelatively high; many annuals.

Faunal richnessVery rich in rodents,

reptiles, and butterflies; the richest bee communities

on Earth.

Soil biotaPoor in species

Example: Khartoum, Sudan 15.5°N

Temperature range: 9°CThe winter and summer are both very warm.Annual total rainfall: 15 cm

Physical Factorsin Hot Deserts

Cold Desert CommunitiesDominant plants

Low stature shrubs and herbaceous plants.

Floral richnessLow, with few species.

Faunal richnessRich in seed-eating birds, ants,

and rodents but low in most other taxonomic groups.

Soil biotaPoor in species

Sagebrush steppe, California, USA

Cold DesertsThe cold desert biome is found in dry regions in the mid to high latitudes, especially in the interiors of large continents. Cold deserts also occur at high altitudes in the rain shadows of mountain ranges.Cold deserts receive most of their small amount of rainfall in winter.

Sagebrush steppe, California, USA

Los Glaciares National Park, Argentina

Savanna

PrecipitationPlants:Animals

Distribution:

The climate is usually

Savanna & Thorn ForestsTropical savannas are found in central and eastern Africa, and in tropical and subtropical regions of South America and Australia. Thorn forests are found on the equatorial sides of hot deserts.Both have mild, dry winters and mild, wet summers.

Unlike savanna, thorn forests generally lack grasses. This reflects the increased aridity of the climate.

Savanna CommunitiesDominant plantsShrubs and small trees;

grasses.

Floral richnessModerate in thorn forest.

Low in savanna.

Faunal richnessRich mammal fauna,

moderately rich in birds, reptiles, and insects.

Soil biotaRich

Temperature range: 10.7°C Annual total rainfall: 74 cm

Example: Kayes, Mali 14°N

Physical Factorsin Savannas

Example: Cheyenne, Wyoming 41°N

Temperature range: 23°CThe winters are cold; summers are much warmer. Annual total rainfall: 38 cm

Physical Factorsin Cold Deserts

Temperature range: 7°CAnnual total rainfall: 42 cm

Example: Monterey, California 36°N

Physical Factors in Chaparral Regions

Chaparral CommunitiesDominant plants

Low stature shrubs andherbaceous plants.

Floral richnessExtremely high in

South Africa and Australia

Faunal richnessRich in rodents and reptiles; very rich in insects, particularly bees.

Soil biotaModerately rich

California, USA

Marmot

Mediterranean/ChaparralThe chaparral biome is found on the western sides of continents at moderate latitudes, where cool ocean waters flow offshore. Such climates are found in:

the Mediterranean (maquis)coastal Californiacentral Chile (matorral) South Africa (cape scrub) south-west Australia (mallee)

Winters are cool and wet whilesummers are long, hot, and dry.

Mediterranean coast

Chaparral

PrecipitationPlants:Animals

Distribution:

The climate is

Temperate ForestsTemperate forests occur throughout mid latitudes where there is a high annual rainfall.Temperate forests are usually deciduous, but where seasonal fluctuations are moderated by proximity to the coast, the forests are evergreen and are termed temperate rainforests.

Temperate rainforests occur in south-eastern Australia,New Zealand, along the Pacific North-West coast of the United States.

Temperate deciduous forest

Temperate rainforest

Temperate Deciduous ForestsTemperate deciduous forests occur throughout mid latitudes where there is sufficient moisture to support large trees.They occur in eastern North America, eastern Asia, and in parts of western Europe.

Rainfall is evenly distributed throughout the year, with cold, snowy winters and warm, moist summers.

Temperate Forest CommunitiesDominant plants

Trees and shrubs

Floral richnessRich shrub layer. many tree

species in southeast USA and East Asia.

Faunal richnessRich: many migrant birds.

The richest biome in amphibians.

Rich in summer in insects.

Soil biotaRich

Temperate (broadleaf)

ForestPrecipitationPlants:Animals

Distribution:

The climate is

Temperature range: 31°C

The temperature fluctuates dramatically between summer and winter.Total annual rainfall: 81 cmAmple falls throughout the year.

Example: Madison, Wisconsin 43°N

Physical Factors in Temperate Forests

Temperate GrasslandsTemperate grasslands or prairies occur in mid latitudes, in regions that are relatively dry for much of the year. They occur in many parts of the world, and include:

The Pampas of ArgentinaThe South African veldtThe Great Plains of the USA

Grasslands are highly productive and large regions have been converted to agriculture.

Grassland CommunitiesDominant plants

Perennial grasses and other herbaceous pasture plants

Floral richnessRelatively rich.

Faunal richnessRelatively rich in mammal fauna. relatively few birds

because of the simple structure.

Soil biotaRich

North American bison

Pronghorn antelope

Temperature range of 24°CThe temperature fluctuates widely, with hot summers, cold winters.

In some grasslands, most precipitation occurs in the winter. In others, the majority falls in summer.

Total annual rainfall: 31 cm

Example: Pueblo, Colorado 38°N

Physical Factors in Temperate Grasslands

GrasslandsPrecipitationPlants:Animals

Distribution:

The climate is

Coniferous Forests (Taiga)The boreal forest biome extends in a broad band across both North America and Eurasia. It is the world’s largest biome.

It is found at high latitudes, south of the tundra and is dominated by coniferous trees.

The winters are long and severe, while the summers are short, and mild and humid.

Taiga CommunitiesDominant plants

Trees (evergreens), shrubs, and perennial herbs.

Floral richnessLow in the tree tops, higher in

the understorey.

Faunal richnessLow, but with summer peaks in

migratory birds.

Soil biotaVery rich in the deep litter

layer.

Temperature range: 41°CTotal annual rainfall: 31 cm

Example: Fort Vermillion, Alberta 58°N

Physical Factorsin Boreal Forests

Taiga / Northern Coniferous or Boreal ForestPrecipitationPlants:Animals

Distribution:

The climate is

TundraThe tundra biome is found in the Arctic and high in the mountains at all latitudes. It is dominated by low-growing perennial plants.

The Arctic tundra is very wet even though rainfall is low and this is because the water cannot drain down through the permafrost (permanently frozen ground).

Tundra: northern Canada

Arctic tundra

Tundra CommunitiesDominant plants

Perennial herbs and small shrubs.

Floral richnessGenerally low; higher in tropical

alpine regions.

Faunal richnessLow: many birds migrate in for

summer, a few species of insects are abundant in

summer.

Soil biotaFew species

Arctic tundra, summer

Migrating caribou, the Arctic

Temperature range: 28°C

Total annual rainfall: 23 cm

Example: Greenland 73°N

Physical Factorsin Tundra

Tundra

PrecipitationPlants:Animals

Distribution:

The climate is

Mountains and IceMountainous regions are associated with their own altitude adapted vegetation.The icy regions of the polar ice caps (the Arctic and Antarctic) form sheets of ice that extend into and over the sea.

What do you notice?What abiotic features do ecosystems with high biodiversity share? Low biodiversity?What abiotic features are most important in determining a biome?

Predicting Biome Distribution 1Temperature and precipitation are excellent predictors of biome distribution. Temperature decreases from the equator to the poles.

Arctic region

Subarctic region

Temperate region

Tropical region

Polar

Latit

udin

al re

gion

s

Equatorial

Annual precipitation (mm)

Predicting Biome Distribution 2Temperature and precipitation act together as limiting factors to determine the type of desert, grassland, or forest biome in a region.