Life: levels of organization

– organism (individuals): any form of life– population: a group of interacting individuals of

same species– community: populations of different species in given

area– ecosystem: community + non–living environment

(e.g. nutrients)– biome: an ecosystem that covers a large geographic

area where plants of certain types live due to the specific climate in the area

BIOMETemperate deciduous forest

BiomesBiomes• Regions of the earth Regions of the earth

that are similar in that are similar in organism type organism type although the although the particular species particular species differdiffer

• Driven largely by Driven largely by climate – temp., climate – temp., water, seasonalitywater, seasonality

• Other factors – soil, Other factors – soil, topography topography

Fig. 50.10 – Biomes of North America

The Major BiomesThe Major Biomes

• TundraTundra• Taiga – the boreal forestTaiga – the boreal forest• Temperate forest, including deciduous and Temperate forest, including deciduous and

conifersconifers• SavannaSavanna• Rain forest – temperate and tropicalRain forest – temperate and tropical• GrasslandsGrasslands• DesertsDeserts

22.5 °C

5 °C40 °C

Bioclimatic tolerancesBioclimatic tolerancesThe survival, growth, & reproduction of organisms is determined, in part, by maximum & minimum tolerance limits for physical conditions such as temperature (bioclimatic tolerances).

TemperatureTemperature• Temperature is Temperature is

partly determined partly determined by the amount of by the amount of solar radiation solar radiation hitting an areahitting an area

• Depends on Depends on latitude, angle of latitude, angle of incidenceincidence

Fig. 50.11

World biomes

Fig. 50.24

Tropical Rain Forest

• Most diverse biome• Characterized by tall

trees, a dense canopy and vines

• Exploited and endangered - half of this biome has been destroyed for cash crops despite poor soil

• 90-100” rain/year

Desert

• Deserts cover 1/3 of the earth’s surface and are spreading because of overgrazing

• Vegetation includes cacti and thorny bushes

• <10” rain/year

Grassland

• Most has been converted to farmland due to rich soils

• Good for crops and grazing animals

• 10-30” rain/year

Temperate Deciduous Forest

• Most exploited biome• Only about .1% of

original forest remain• This is our biome• 30-80” rain/year

Coniferous Forest (Taiga)

• Logging has stripped many parts of this biome

• Vegetation primarily evergreen trees

• 15-40”rain/year

Taiga Forests & Boreal ClimateTaiga Forests & Boreal Climate

Coniferous forests occur where winter temperatures are low and precipitation is abundant..

Tundra

• Vegetation limited, mostly lichens, moss and grasses

• Not enough precipitation for trees

• “permafrost” frozen soil

• <10”rain/year

Tundra VegetationTundra Vegetation

Extremely short growing seasons keep woody vegetation short and scattered, with ground cover is comprised mostly of mosses and lichens.

October 2006 27

current climate

modeled future climate

possible vegetation shifts under global warming in North America

Vertical Climate ChangeVertical Climate Change

Ascending a mountain brings changes in temperature and precipitation, and so to will bring changes in vegetation types and micro-climates, as illustrated in this sketch that moves from grassland to tundra and icecap across a short distance of 180 km, and up a steep elevation of 4 km.

Species dispersalSpecies may not inhabit Species may not inhabit an area because of an area because of biogeographical biogeographical boundaries.boundaries.

Transplantation Transplantation studies can give us studies can give us information about information about potential ranges.potential ranges.

Fig. 50.6

12/1/06 34

Arctic vegetation-climate feedbacks

Chapin et al. 2005

Describe this diagram in words