Ecosystems: What Are Ecosystems: What Are They and How Do They They and How Do They

Work?Work?

Chapter 3Chapter 3

Sections 5-7Sections 5-7

Importance of SoilsImportance of Soils Provides nutrients for plant growth (Base of Provides nutrients for plant growth (Base of

life on land)life on land)

Water Cleansing & StorageWater Cleansing & Storage

Helps decompose & recycle wasteHelps decompose & recycle waste

Potentially renewable resourcePotentially renewable resource(1 cm of soil requires 15yrs to several hundred years to form)(1 cm of soil requires 15yrs to several hundred years to form)

Climate Control - COClimate Control - CO22 storage storage

Soil HorizonsSoil Horizons

O Horizon = surface litter - O Horizon = surface litter - Brown or BlackBrown or Black Non-Non-decomposed leaves, twigs, crop & animal waste, fungi , decomposed leaves, twigs, crop & animal waste, fungi ,

A Horizon = A Horizon = Topsoil - Dark & LooseTopsoil - Dark & Looseporous mixture of partially decomposed porous mixture of partially decomposed humushumus, and inorganic minerals, and inorganic minerals

B Horizon = subsoilB Horizon = subsoil

C Horizon = C Horizon = Parent MaterialParent Material

Oak tree

Woodsorrel

Lords andladies

EarthwormDog violet

MoleMillipede

Honeyfungus

Organic debrisbuilds up

Moss andlichen

Rockfragments

Bedrock

Immature soil

Regolith

Young soil

PseudoscorpionMite

Nematode

Actinomycetes

FungusBacteria

SpringtailRed earthmite

Mature soil

Root system

C horizonParent material

B horizonSubsoil

A horizonTopsoil

Grasses andsmall shrubs

Fern

Fig. 3-21, p. 51

Soil Formation and HorizonsSoil Formation and Horizons

O horizonLeaf litter

Fig. 3-22, p. 52

Soil Profiles Soil Profiles from Different from Different

EcosystemsEcosystems

Gray,

Gray, yellow & red topsoils are low in organic matter

& need N to support crops

Soil profiles interaction

AnimationAnimation

pHpH

Acidity or alkalinity of water or water-bearing samplesAcidity or alkalinity of water or water-bearing samples

Scale 0-14Scale 0-14

Acidic: pH 0-6.9Acidic: pH 0-6.9

Neutral pH 7.0Neutral pH 7.0

Alkaline (basic): pH 7.1-14Alkaline (basic): pH 7.1-14

The pH ScaleThe pH Scale

Fig. 3-23, p. 192

Matter Cycling in Ecosystems: Matter Cycling in Ecosystems: Biogeochemical CyclesBiogeochemical Cycles

Nutrient (biogeochemical) cyclesNutrient (biogeochemical) cycles

Hydrologic (water) cycleHydrologic (water) cycle

Carbon cycleCarbon cycle

Nitrogen cycleNitrogen cycle

Phosphorus cyclePhosphorus cycle

Sulfur cycleSulfur cycle

PrecipitationPrecipitation

to land

Evaporation

EvaporationFromocean

Ocean storage

Condensation

Transpiration

Rain clouds

Infiltration andpercolation

Transpirationfrom plants

Groundwater movement (slow)

Precipitation

Simplified Hydrologic (Water) CycleSimplified Hydrologic (Water) Cycle

Fig. 3-24, p. 54

Surface runoff (rapid)

EvaporationFromocean

Rapid Precipitationto ocean

Surface runoff (rapid)

Water cycle interaction

AnimationAnimation

Human Interventions in the Human Interventions in the Hydrologic CycleHydrologic Cycle

1.1. Large withdraw of surface and ground watersLarge withdraw of surface and ground waters

2.2. Clearing vegetation / wetland destructionClearing vegetation / wetland destruction - - runoff, runoff, infiltration, infiltration, groundwater recharge, groundwater recharge, flood risk, flood risk, soil soil erosion & landslideserosion & landslides

3.3. PollutionPollution - addition of nutrients - addition of nutrients

Diffusion betweenatmosphere and ocean

Carbon dioxidedissolved inocean water

Marine food websProducers, consumers,

decomposers, detritivores

Marine sediments, includingformations with fossil fuels

Combustion of fossil fuels

Fig. 3-25a, p. 56

The Carbon Cycle (Marine)The Carbon Cycle (Marine)

sedimentation

uplifting over geologic time

photosynthesis aerobic respiration

death, sedimentation

incorporation into sediments

Atmosphere(most carbon is in carbon dioxide)

Terrestrialrocks

Land food websProducers, consumers,

decomposers, detritivores

Peat,fossil fuels

Soil water(dissolved carbon)

Combustionof fossil

fuelsvolcanic action

Fig. 3-25b, p. 57

The Carbon Cycle (Terrestrial)The Carbon Cycle (Terrestrial)

photosynthesis

death, burial, compaction over geologic time

aerobic respiration

deforestaion

combustion of wood (for clearing

land; or fuel)

weathering

leaching, runoff

Carbon cycle animation- LEARN THE CARBON CYCLE!

AnimationAnimation

Fig. 3-26, p. 56

Highprojection

Lowprojection

Human Interferences in the Human Interferences in the Global Carbon CycleGlobal Carbon Cycle

1. Clearing Vegetation

2. Burning Fossil Fuels

potential consequences?

Gaseous Nitrogen (N2)in AtmosphereNitrogen

Fixationby industry

for agricultureFood Webs

on Land

Fertilizersuptake byautotrophs

excretion, death,decomposition

uptake byautotrophs

Nitrogenous Wastes,Remains in Soil

NO3–

in Soil

NO2–

in Soilloss by

leaching

1. Nitrificationbacteria convert NH4

+

to nitrite (NO2–)

2. Nitrificationbacteria convert NO2

–

to nitrate (NO3–)

Ammonificationbacteria, fungi convert the

residues to NH3; thisdissolves to form NH4

+

NH3, NH4+

in Soil

loss byleaching

Nitrogen Fixationbacteria convert N2 toammonia (NH3); this

dissolves to formammonium (NH4

+)

Denitrificationby bacteria

Fig. 3-27, p. 58

The Nitrogen CycleThe Nitrogen Cycle

Nitrogen cycle interaction - LEARN THE NITROGEN CYCLE!(Animations on School Server)

AnimationAnimation

Human Interferences in the Human Interferences in the Global Nitrogen CycleGlobal Nitrogen Cycle1.Add nitric oxide (NO) to atmosphere -

can form acid rain2.Add nitrous oxide N2O to atmosphere via

anaerobic decomposition & inorganic fertilizers - greenhouse gas

3.Nitrate in inorganic fertilizers can leach thru soil & contaminate groundwater

4.Release large quantities of N into troposphere via habitat destruction

5.Upset aquatic ecosystems from excess nitrates in ag. runoff & sewage- eutrophication

Marine Sediments Rocks

Marine Food Webs

Dissolvedin Ocean

Water

Dissolvedin Soil Water,Lakes, Rivers

LandFoodWebs

Guano

Fertilizer

excretion

uptake byautotrophs

death,decomposition

sedimentation settling outuplifting overgeologic time

weathering

uptake byautotrophs

weathering

mining

leaching, runoff

agriculture

Fig. 3-29, p. 59

The Phosphorus CycleThe Phosphorus Cycle

Phosphorus cycle animation

AnimationAnimation

Human Interventions in the Human Interventions in the Phosphorus CyclePhosphorus Cycle

1. Mining of phosphate rock

2. Clearing tropical forests reduces available phosphate in tropical soils

3. Phosphates from runoff of animal wastes, sewage & fertilizers disrupts aquatic ecosystems - eutrophication

“Since 1900, human activities have increased the natural rate of phosphorous release to environment by about 3.7 fold”

Ocean

Hydrogen sulfide

Industries

Volcano

Oxygen

Water AmmoniaSulfur trioxide Sulfuric acid Acidic fog and precipitation

Ammonium sulfate

Plants

Animals

Sulfate salts

Hydrogen sulfide

SulfurDecaying matterMetallicSulfidedeposits

Dimethyl sulfide

Sulfur dioxide

Fig. 3-30, p. 60

The Sulfur CycleThe Sulfur Cycle

Sulfur cycle animation

AnimationAnimation

How Do Ecologists Learn How Do Ecologists Learn about Ecosystems?about Ecosystems?

Field researchField research

Remote sensingRemote sensing

Geographic information system (GIS)Geographic information system (GIS)

Laboratory researchLaboratory research

Systems analysisSystems analysis

Fig. 3-31, p. 61

Wetland Lake

Critical nesting site locations

USDA Forest Service

Topography

Habitat type

Real world

Privateowner 1

Private owner 2

USDAForest Service

Grassland

Forest

Geographic Information System (GIS)Geographic Information System (GIS)