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.