The Biosphere

The Biosphere(1) WHAT IS THE BIOSPHERE?

- The living layer which includes all organisms & their habitat, that is:

lithosphere + hydrosphere + atmosphere (solid layer: (water layer: ice, glaciers, (air layer)sediments & soil) seawater, freshwater)

(2) BIOGEOCHEMICAL CYCLES

- occurs when a life sustaining substance (ex. C, H2O, N, & P) cycles throughout the planet in an expected way creating a perpetual multi step loop- A biochemical cycle incorporates biological cycle (ex. photosynthesis, digestion…), geological processes (ex. erosion, sedimentation…), & chemical processes (ex. synthesis, oxidation…)- 3 cycles in this chapter: (1) carbon, (2) nitrogen, (3) phosphorous

2.1 CARBON CYCLE

- Carbon: element common to all living beings; building block for carb’s, prot’s, & fats; found in import. gases (CO2, CH4); during cycle C travels through living & dead beings, atm., rocks, soil, & ocean- Fossil fuel has upset the natural C cycle balance, esp. since the beginning of the industrial era, increasing CO2 & CH4 production in atm.

Carbon Cycle Components (reminder: all cycles loop; therefore there is no beginning or end just movement)

1. Photosynthesis

-Pl. (producers) use CO2 from the atm. combined with solar ener. to produce glucose, used for pl. cell development

2. Ingestion

-Herbivores & carnivores assimilate (eat) carbon in order to grow

3. Respiration

-Organisms exhale which releases some C (in the form of CO2) to the atm.

4. Decomposition of waste

-C not released through respiration is found in excretions (urine, feces, sweat) & in the form of dead animals; these are broken down by decomposers which emit CO2 & CH4 in the process

5. Forest fires

-Combustion of wood transforms the C found in leaves & branches into CO2

6. Shells & skeletons

-Some of the CO2 that dissolves in oceans reacts with calcium forming calcium carbonate (CaCO3) a building block of marine organism skeletons & shells

7. Carbonate rock

-CaCO3 found in skeletons & shells of dead & decomposing marine organisms form marine sediments which are compacted over time yielding carbonate rock; through tectonic activity, some of this rock is brought back to the surface

8. Volcanic eruption

-During volcanic eruptions certain carbonate rocks can be melted by hot magma transforming some of the C in the rock into atmospheric CO2

9. Fossil fuels

-Dead organisms decompose & get compacted under layers of sediments; over hundreds of millions of yrs (thus considered nonrenewable) fossil fuels form from these decomposed residues

CAN YOU PLACE NUMBERS 1-9 IN THE DIAGRAM? (text p.256)

If something is missing add it to the diagram.

2.2 NITROGEN CYCLE

-N is needed by living beings to produce protein and DNA, both of which are found in their cells

- Bacteria is needed to change N in the atm. into either ammonia (NH3), ammonium (NH4+), nitrites (NO2-) or nitrates (NO3-) since N2 cannot not be absorbed directly by most organisms

-Natural factors such as relative humidity, T, and pH affect N cycle

-Human activities such as the use of fertilizers (rich in NH3, NH4+, and NO3-) to boost crop growth or the discharge of N rich wastewater by industries in waterways greatly affect the soil and the environment, offsetting the N cycle’s balance

- In a nutshell: atmospheric N enters the earth, undergoes several modifications, & is later released back into the atm.

Nitrogen Cycle Components

1. Nitrogen fixation-Specialized bacteria harness N from the atm. and convert it to ammonia (NH3); on contact with H some of the ammonia is converted to ammonium (NH4+)

2. Nitrification (process by which a nitro grp. is added to an organic cmpd, i.e., a cmpd with O2) - Some bacteria oxidize ammonium (NH4+) to form nitrites (NO2-) -Other bacteria oxidize nitrites (NO2-) to form nitrates (NO3-)

3. Nitrogen absorption by plants & animals- Pl. can absorb ammonium (NH4+) or nitrates (NO3-) from the soil or the water- Herbivores take in their needed N by eating pl.’s-Carnivores take in their needed N by eating herbivores or other animals which have N in their tissues

4. Decomposition of waste-Specialized bacteria or fungi decompose pl. and an. waste (dead pl.’s & an.’s, feces, urine…) and convert it to ammonia (NH3) which dissolves to form ammonium (NH4+)

5. Denitrification (opposite of nitrification)- N returns to the atm. as certain bacteria breakdown nitrates (NO3-) into elemental N CAN YOU PLACE NUMBERS 1-5 IN THE DIAGRAM? (text p.259)If something is missing add it to the diagram.

2.3 PHOSPHORUS CYCLE

-P is a building block of DNA; P also enters in the composition of shells, bones, & teeth

-Phosphates (PO43-), a form of P cycles constantly through living beings, the lithosphere, & the hydrosphere

-Human activities such as the use of phosphate rich fertilizers or residential & industrial wastes containing phosphate residues from soaps & detergents greatly offset the balance of the natural cycle

-Runoff from these activities leach into waterways & eventually end up in lakes where cultural eutrophication occurs, thus depriving lakes of life sustaining O2

Phosphorus Cycle Components

1. Erosion - P is naturally occurring in rocks-Wind & rain slowly erodes P from rocks, pieces of which contain phosphates

2. Absorption by living organisms-Pl.’s will readily absorb phosphates & make it part of their tissues; herbivores & carnivores will in turn get theirs from eating pl.’s or other animals

3. Decomposition of waste- Phosphates digested by animals return to the soil in the form of feces & urine-When specialized bacteria breakdown dead pl.’s & an.’s, phosphates are released to the environment

4. Proliferation of plankton & sedimentation- Phosphates released in #3 eventually make their way to the oceans- Some phosphates will boost plankton growth; plankton are tiny marine organisms which are either of pl. origin: phytoplankton or of animal origin: zooplankton; plankton is at the base of marine food chains & it is necessary for their equilibrium- Some phosphates will sink to the bottom of the ocean where they become part of the sea floor sediments; over millions of years the mixture will compact forming rock beginning the cycle once again

(3) BIOMES

- are vast regions of the planet that have their particular flora, fauna, & climate- 2 types: (1) terrestrial biomes & (2) aquatic biomes

3.1 FACTORS DETERMINING BIOME DISTRIBUTION:

these conditions dictate where beings can live; they limit the distribution of spp.

-Import. factors for terrestrial biomes: - Import. factors for aquatic biomes:

1. Latitude 1. Salinity2. Altitude 2. Turbidity (am’t of suspended particles in water)3. Precipitation 3. T4. Soil type 4. Conc.’s of O2 (respiration) & CO2 (photosynthesis) 5. Am’t of solar ener. 5. Am’t of solar ener.6. Winds 6. Nutrients (type, availability …)7. Proximity to water 7. Depth of water

3.2 TERRESTRIAL BIOMES

- Land biomes; T & precipitation are very import.

-TROPICAL FORESTS

- Situated bet. the Tropics of Cancer (23 ½ °N of Equator) & Capricorn (23 ½ °S of Equator)- fig. 8.8, p.264- Mean annual T bet. 20°C & 34°C- Occupy only 10% of the Earth’s landmass but home to 50 to 80% of the planet’s spp.- Holds the greatest biodiversity & contributes to climate regulation because of its high biomass density; tropical forests represent an immeasurable environmental wealth- threatened due to clearage for farm use & for timber; in 30 yrs millions of hectares

(1 hectare = 2.471 acres or 10,000 m2) have been sacrificed in the name of economic profit, changing the landscapes & causing even more climate change -2 types of tropical forests:

(1) Seasonal tropical forest: mainly in Africa; dry & rainy seasons alternate;

(2) Evergreen tropical forest (rainforest): mainly in South America & Asia; rainy season only, up to 10m of rain yearly

-BOREAL FORESTS

-Make up more than 25% of the world’s forests; forming a vast green arc under the Arctic Circle

-Made up conifers (esp. black spruce – Xmas tree), marshland, lakes, & rivers

-Although acidic, shallow, & lacking in nutrients, the soil sustains an impressive quantity of spp.

-In summer sunlight can be up to 18 hrs long; promoting growth

-Source of timber; an import. raw material

-Although devastating at times, fire, pests, & disease are part of this biome’s natural cycle; of greater threat is the excessive logging, the damages caused by this industry, & the poorly designed restoration plans

-- The boreal forest spans across Canada, parts of northern Europe, & Russia

- A huge area of the boreal forest has been destroyed & mismanaged which is unfortunate & even somewhat baffling since it is considered a renewable resource; other areas have been cleared for habitation; the map above shows the original extent of the boreal forest 8,000 yrs ago

- The Sleeping Like a Log campaign, from the Aux Arbres Citoyens conservation group, aims to inform & desensitize the public & a petition can be signed online- http://ondortcommeunebuche.citoyenpourlanature.com/en/petition/index.asp

-TEMPERATE FORESTS

-Found in southern Canada, US, Europe & in parts of Asia

-In upper levels this forest consists of a mixture of deciduous (broad leaf; esp. maple, beech, & birch) & coniferous trees, while in lower levels the forest contains mostly deciduous trees

-Covers the Great Lakes & the St. Lawrence Valley; mean annual T: bet. 8°C & 10°C

-The soil is very rich due to nutrient rich decomposing leaves; soil is able to sustain various spp. such as moss & grass at ground level, bushes at an intermediate level & final trees at a higher level; this rich pl. life provides the perfect ecological niche for many animals

-A substantial portion of the temperate forest in Canada was lost to important urban centers such as Toronto & Montreal the reason being that this forest is found in proximity to major waterways which were at the root of city development

-Areas of primary forest (a forest that has never been cut) are extremely rare

-ARCTIC TUNDRA

-An arc of green surrounding the North Pole that is sandwiched bet. the Arctic Circle & the boreal forest; covers the Canadian Far North (Baffin Island, northern Quebec…)

-6% of the world’s landmass; more than 8,000,000 km2

-Grasses, moss, lichen, & dwarfed bushes in the tundra offer enough nutrients & adequate reproduction sites for many migratory birds (ex. snowy owl – the official bird of Quebec, eiders, geese…)

-Pl. growth diminished by long cold winters & very short summers that offer 24 hr daylight

-A layer 1m deep thaws by the summer sun where the aver. T is 10°C; lower permafrost layer does not thaw

-Also home to permanent spp.: arctic fox, lemmings, caribou (picture), arctic hare…

-Extremely fragile to climate change where global warming is happening at twice the rate