BIOMES AND AQUATIC ECOSYSTEMS

A. BiomesMajor types of terrestrial ecosystems.

Distribution of biomes largely depends on climate (temperature & rainfall).

Climate is determined by the Earth’s tilt & uneven heating of Earth’s surface.

Tilt produces seasons in northern & southern hemispheres.

Earth’s tilt produces…?

Unequal heating causes air movements that distribute moisture.

Altitude influences climate - conditions usually become drier & colder as altitude increases.

Air circulation & biomes

Note the closed air cells?Wind patterns distribute suns heat=??Ocean currents too related to weather??

Elevation & biomes

Rain shadow effect

Earth’s major biomes

1. Tropical Rain Forest

warm & moist (rainfall: 79-157 in/yr)nutrients cycle rapidlysoils are nutrient poorplants exhibit vertical stratificationvery high biodiversity

Tropical Rain Forest

Avg high tempHigh avg rainfallAdaptations?

2. Tropical Dry Forest

wet & dry seasons temperature fluctuatessoils are rich in nutrients organisms adapted to seasons

Tropical desert

Avg high tempLittle rainfallAdaptations??

3. Tropical Savanna

wet & dry seasons (rainfall: 12-20 in/yr)mainly grasslands; few scattered trees & shrubsorganisms adapted to wet/dry seasons (migrating herbivores)frequent fires maintain grassland

4. Desert

dry (rainfall: < 8 in/yr)hot days / cool nightsplants adapted to obtain & store water

rapid life cyclesdeep roots (mesquite)succulent tissues / reduced leaves (cacti)

Temperate desert

High avg tempLow rainfallAdaptations?

animals adapted to minimize water loss

tough, waterproof integumentconcentrated urinenocturnal habits

Atriplex (saltbush plant) stores salt in outer cells of leaves.

Red vizcacha rat has adaptation that allows it to feed on Atriplex.

5. Temperate Grasslands (prairie)

1 or 2 dry seasons/year (rainfall: 10-40 in/yr)lack trees & shrubsgrazing & frequent fires maintain grassIn US, majority of prairie has been replaced by farmland.

Temperate grasslandFreezing ‘vernalizes’ seedsVery productive

Grassland

Dry seasonRainy seasonAvg high temp

6. Temperate Forestsrainfall: 26-118 in/yr

Temperate forests are either deciduous or coniferous.

Temperate Deciduous Forestoak-hickory or beech-maple predominatemoist growing season (at least 4 months)soil rich in nutrientsvertical stratificationorganisms adapted to seasonal changes

Temperate deciduous forest

Leaves lost in winter…why?

Temperate Coniferous Forest

spruce, pines, firs & hemlocks predominatesummers typically dry; long, harsh winterssoil is thin, acidic & poor in nutrientsunderstory of shrubsadapted to recurring fires

7. Taiga (boreal forest)

precipitation falls as snow/ice (8-24 in/yr)long, cold winterssoil is thin, moist, acidic & nutrient poor (subsoil may be frozen)biodiversity lower than temperate zoneconifers predominate

Taiga

Average low tempAvg. low rainfallI.e. ‘frozen desert’

8. Tundra

Precipitation: 8-24 in/yr

long, bitterly cold winters permafrost begins 18 in. below surfacelow biodiversityshallow-rooted shrubs & lichensplants adapted to short growing seasonanimals adapted to cold (small extremities) & snow (many are camouflaged)

Tundra

Low avg tempLow rainfallAdaptations?

Polar Desert

Note avg higher temp than tundra

Aquatic Ecosystems Freshwater Ecosystems

Lakes and Ponds (standing water)

littoral zonelimnetic zoneprofundal zonebenthic zone

Oxygen & nutrients (nitrogen/phosphorus) are unevenly distributed in lakes.

O2 level is highest near surfacenutrient level is highest near bottom

Oxygen & nutrients are redistributed by:

wind (ponds & shallow lakes)

fall & spring turnover (deep lakes in temperate regions)

Oligotrophic lakesyoung; low in nutrients & productivityclear & sparkling bluedeep water is oxygen-rich

Eutrophic lakesolder; nutrient rich & high in productivitygreen & murkyO2 often depleted in deep water during summer

Nutrients in sewage & agricultural runoff speed eutrophication.

Rivers and Streams (running water)Transport rainwater, groundwater, snowmelt &

sediment from land to ocean or lake.

At headwaters:channel is narrowwater is clear & oxygen-richcurrent is swift

At mouth:channel widens

water is murky & contains less oxygencurrent slows, depositing sediment

2. Marine EcosystemsCoastal EcosystemsInclude estuaries, mangrove swamps, the

intertidal zone & coral reefs.

Estuary - area where fresh water of river meets salty water of ocean.

water is brackishsalinity fluctuatesvery productivehigh biodiversitynursery for many ocean animals

Ocean currents & biomes

Mangrove Swamp - tropical wetland dominated by salt-tolerant plants (mangroves).

transitional zone between forest & oceansalinity fluctuatesplants have aerial rootshigh biodiversity

Intertidal Zone - area along coast between high & low tides.

organisms adapted to pounding waves & varying degrees of desiccationlow productivity

Coral Reef - underwater deposits of calcium carbonate formed by colonies of animals.

very productivehigh biodiversityvery fragile

Ocean Ecosystemcovers 71% of Earth’s surfacetemperature: 35oF - 81oFsunlight quickly dissipates with depthprimary producers are photoautotrophs (found near surface) & chemoautotrophs (found at deep-sea hydrothermal vents)

highest productivity near upwellings (occurs on western side of continents)

And, what did we learn?

What is a biome? List 2 major factors that determine?List 7 major biomes & climatesCompare freshwater ecosystemsLakes vs flowing sourcesMarine ecosystems (coastal & open)

What is an ECOSYSTEM?

Total interactions of living and nonliving things in a defined area.Composed of ENERGY and NUTRIENT inputs/outputs

Energy flow in an ecosystem

One-way flow…High ‘quality’ to…Low ‘quality’ is…EntropyEnergy is NOT recycled!

Nutrient recycling (i.e. Carbon)

Food chains

Decomposers…important?

A food/energy pyramid

What happens at each level?Why are there fewer consumers than producers?Why are decomosers at all levels?

Food/Energy WEBS

Series of food chainsInterlacedMore stable than food chain…why?

GRAZING…DETRITAL…

Primary productivityBiomass pyramids??Energy pyramid

Kilocal/M2/year

Relative Biome productivity

El nino…Southern oscillation

Population diversity vs space