Biogeochemical Cycles and the Biosphere

Hydrologic & Carbon Cycles Water Budgets & Movement Photosynthesis & Respiration Soil Formation Global Patterns of Soil Interaction of Ecosystems Food Chains & Trophic Levels Biodiversity World Biomes

Recycling processes that supply needed substances for the biosphere

Examples◦ Water◦ CO2◦ Nitrogen

Law of Conservation◦ Energy cannot be

created or destroyed◦ May be changed from

one form to another Energy and matter

are continually transformed in the biosphere

Life requires matter (chemicals) & energy. Earth system is closed (to matter), but

media (air and water) allow matter to flow between components (reservoirs).

Biogeochemical CYCLES transfer necessary nutrients and material to sustain life.

The system requires energy…

Which biogeochemical cycle is the “most obvious”?

A.HydrologicB.CarbonC.Nitrogen D.Oxygen

Answer: B - Carbon plays the central role in the "reduction-oxidation battlefield" that we call life.

Water = central to every part of the biosphere◦ Only common substance that exists as solid,

liquid, & gas at normal temperatures◦ Large amounts of heat energy is transferred◦ Excellent solvent◦ All living things are water (70% humans)

Water is stored in the atmosphere, hydrosphere, & lithosphere

Oceans = greatest reservoir

Precipitation: water that condenses from a vapor and falls as rain or snow on the earth’s surface

Runoff: the portion of precipitation on land that ultimately reaches streams; flow from a stream into another body of water

Evaporation: water converted from liquid form in to vapor; water transferred from a liquid water body (stream, lake, ocean, moisture in soil, etc.) into the atmosphere

Transpiration: the passage of water vapor from a living body into the atmosphere through a membrane or pores

Evapo-transpiration: the combination of evaporation and transpiration

97% of the water in the globe resides in the oceans

22% of precipitation occurs over land, and is greater than losses by evaporation and transpiration

The processes of evaporation, transpiration, and precipitation

cycle water through ecosystems

78% of precipitation occurs over ocean, which is less than losses by evaporation

Water Cycle

97% of the water in the globe resides in the oceans

22% of precipitation occurs over land, and is greater than losses by evaporation and transpiration

The processes of evaporation, transpiration, and precipitation

cycle water through ecosystems

78% of precipitation occurs over ocean, which is less than losses by evaporation

If water is neither being created nor destroyed, then ◦ the amount of water on earth is constant◦ we can make a water budget

In a water budget, we select an area or volume of the earth and set up an “accounting ledger” for our “water account” for this area or volume.

Two rivers that fed the Aral Sea, the Amu Darya in the south and the Syr Darya in the northeast, would be diverted to irrigate the desert, in order to attempt to grow rice, melons, cereals, and cotton.

Geological ◦ Enters through rock

formation Weathering Erosion

◦ Deposits of coal, petroleum, and natural gas derived from once-living things

◦ Soils

Biological ◦ PhotosynthesisCO2+H20+Energy = Carbs

+ O2◦ Respiration (Returns) Carbs+O2 = CO2 + H20 +

Energy (heat)

*Note: All living things need carbon and oxygen to sustain life

Cannot ignore the human affects on CO2 levels

Greenhouse gases

Carbon dioxide is the largest single

contributer to climate forcing

Carbon dioxide contributes about half of total climate forcing from

greenhouse gases

Inorganic-C in rocks (such as bicarbonate and carbonate)

Organic-C (such as found in organic plant material)

Carbon gases such as CO2 (carbon dioxide), CH4, (methane), and CO (carbon monoxide) 

LOCATION Amount (x1015 gC)

Rocks 65,000,000

Oceans 39,000

Soils 1,580

Atmosphere* 750

Land plants 610

Porous layer of mineral and organic material, in which plants grow

Soils consists of: Mineral particles – determine soil textureOrganic matterAir and WaterSoil organisms

Soils form from rock by ’weathering’

physical◦ freezing, thawing,

wetting, drying, organisms

chemical◦ dissolved minerals

moved in water◦ soil horizons formed

1 inch = 100 yearsFormed vertically (unlike layers of sediment)

O - organic horizons. A - predominatly mineral horizon that is mixed with humified

organic material (an eluvial horizon, i.e. a source of organic material, clay, and cations to lower horizons).

E - light colored, bleached mineral horizon underlying the A horizon that occurs only in highly leached acidic soils.

B - mineral horizon that shows little or no evidence of the original rock structure and which has been altered by oxidation, and illuviation (addition of minerals, clays, and organic matter from the A horizon).

K - a subsurface horizon that is characterized by accumulation of calcium carbonate. Occurs mostly in desert and dry areas.

C - a subsurface horizon that is basically the material from which the soil formed (loess, alluvium, till, etc.). It lacks most of the properties of the A or B horizon, but can be somewhat

R - regolith (consolidated bedrock).

Soils are classified into orders based on the presence or absence of diagnostic horizons and major differences in soil forming factors or properties.

There are 11 soil orders. There are some soil orders that generally

correspond to specific conditions:

Arid Organic ForestsVolcanic Highly oxidized CrackingFrozen Prairie Young

Inceptisol – weakly developed soils often found in mountains

Mollisol – grassland; plentiful organic material

Humid & Subtropical◦ Highly weathered◦ Lost nutrients due to

heavy precipitation◦ Fertilization needed

Arid ◦ High in soluble

materials◦ Low in organics◦ Irrigation needed

Midlatitude Soils◦ Moderately leached◦ Deciduous Forests◦ Coniferous (acidic)

Midlatitude Subhumid Soils◦ Fertile◦ Grain-Producing Regions

Mountain Regions have poor soils due to heavy erosion

No continent is free of soil degradation

1.2 billion have moderately to severely degraded (especially Asia and Africa)

Central America highest percentage and worst degrees of soil degradation

Central part of USA very degraded soils

Intensive agriculture accelerates degradation (loss of nutrients)

Ability to support plant growth Agriculture

◦ Fallow period (no harvest; fields allowed to rest)◦ Inorganic fertilizers replace organic materials

Concern about impact on world’s food-producing capacity

Desertification◦ Caused by climate change, erosion, and

degradation of soil in dryland areas◦ Spreads outward from any where excessive abuse

of the land occurs and far from any climatic desert

Poor irrigation practices and the unsustainable exploitation of water resources are contributing to chemical pollution, soil salinization and aquifer depletion.

The study of ecosystems mainly consists of the study of certain processes that link the living, or biotic, components to thenon-living, or abiotic, components.

Circle of Life

Mufasa: Everything you see exists together, in a delicate balance. As king, you need to understand that balance, and respect all the creatures-- from the crawling ant to the leaping antelope.

Simba: But, Dad, don't we eat the antelope?

Mufasa: Yes, Simba, but let me explain. When we die, our bodies become the grass. And the antelope eat the grass. And so we are all connected in the great Circle of Life.

Ecosystem = a “major interacting system that involves both organisms and their nonliving environment" (Molles 2002) - who defines ecosystems as having the most complex level of biological organization.

Biome = Widespread terrestrial ecosystems.Biomes are major communities of organisms that have a characteristic appearance and that are distributed over a wide land area defined largely by regional variations in climate.

Abiotic (Non-living)◦ Sunlight◦ Temperature◦ Precipitation◦ Water or Moisture◦ Soil or Water

Biotic (Food Chain)◦ Primary Producers

(autotrophs) ◦ Carnivore (meat-eaters)◦ Herbivore (plant-eaters◦ Omnivore (eats either

other animals or plants)◦ Decomposers

All of these vary over space/time

Trophic Level – each step in the food chain

Succession is the natural transition of plant species from a "pioneer stage" to a "climax community"

Beginning Stage

Climax Community – End point (equilibrium)

Earth can be divided into Biomes Occupy large regions Plants & animals Have specific climate with similar plants and animal adaptations

Note: Many of the locations of these biomes on the map correspond topatterns of the annual precipitation and annual temperatures --->

Forest Savanna Grassland Desert Tundra

* Some biomes and climate types share the same names

Found only in Northern Hemisphere

Very short growing season

Mosses, lichens, no trees

Permafrost restricts root growth.

Reason for small plants.

Low & Midlatitudes Widely spaced

plants Plants store

water (cacti) Many types of

animals, well adapted

Midlatitude Names: Steppe,

prairie, plain, etc.

Temperate & Tropics similar

Unbroken sea of grass

Grazing adapted plants

Wet & Dry Seasons

Tropical grassland

Scattered trees and shrubs

Herds of grazing animals

Spreading

Tree covered Determined by

types of trees◦ Temperate Forests

Deciduous Coniferous Mixed Boreal (Northern) Mediterranean Forest

◦ Tropical Rain Forests

Deciduous ForestsTropical Rain ForestsConiferous Forests

Which biome covers most of the U.S.?A. TundraB. Deciduous ForestsC. Coniferous ForestsD. Grassland

Which biome does not exist in the U.S.?

A. TundraB. Rain ForestsC. DesertsD. Savannas

A study published in 1999 concluded that there are 150 different "ecoregions" in North America alone.

1. All living things – plants, animals, and humans, - are interrelated in the biosphere.

2. Biogeochemical cycles always involve equilibrium states: a balance in the cycling of the element between compartments

3. Carbon is the basis of life on Earth.4. Soil provides the nutrients plants needs to grow

and survive.5. Biomes are the various regions of our planet

which can best be distinguished by their climate, fauna and flora.