Ecosystems: Basics

Definition Structure Components Needs

Definition

An Ecosystem is:

All the communities that live in an area as well as the abiotic factors of water, soil and climate

Structure

Highly organized and well structured environment in which all parts exist in balance

Components of the Ecosystem

Habitat: type of environment in which a species lives

Species: group of similar organisms that can breed and reproduce

Population: members of a species that live in the same area

Community: all the populations that live and interact in the same environment

Biodiversity: variety of species

Levels of Organization

Needs of Organisms so they will survive in the Ecosystem:

Water, energy, living space, suitable climate

So, remember the difference between biotic and abiotic??

Ok, let’s talk about how organisms needs will be met.

1. Water – 2. suitable climate 3. Living Space 4. Energy – this one we need a little

more discussion on…..hence, we will learn a bit about soil and nutrient cycling as organisms need nutrients and energy

How do organisms get energy??

Producer is…. And gets energy from the ……

Consumer is …. And gets energy from…. Herbivore Carnivore Omnivore Scavengers

Decomposers are …. And gets energy from

How are nutrients and Energy Related?

Humans and other consumers need nutrients from plants to get energy

(read connect)

Important Nutrients that are found in soil

Nitrogen Color and size

Phosphorous New seedlings, formation of roots and

development of seeds and fruits, transfer of energy

Potassium Plant metabolism, resistance to disease,

synthesis of starch

Why those nutrients are important for humans:

Oxygen (65%) and hydrogen (10%) are predominantly found in water, which makes up about 60 percent of the body by weight. It's practically impossible to imagine life without water.

Carbon (18%) is synonymous with life. Its central role is due to the fact that it has four bonding sites that allow for the building of long, complex chains of molecules. Moreover, carbon bonds can be formed and broken with a modest amount of energy, allowing for the dynamic organic chemistry that goes on in our cells.

Nitrogen (3%) is found in many organic molecules, including the amino acids that make up proteins, and the nucleic acids that make up DNA.

Phosphorus (1%) is found predominantly in bone but also in the molecule ATP, which provides energy in cells for driving chemical reactions.

Potassium (0.25%) is an important electrolyte (meaning it carries a charge in solution). It helps regulate the heartbeat and is vital for electrical signaling in nerves.

Carbon Cycle

14

Nitrogen Cycle

Movement through the atmosphere is generally rapid

-- Movement through the soils is generally slow

-- Movement from terrestrial biosphere to the ocean (via stream flow, usually) must be replaced by movement either through the atmosphere (such as with nitrogen and carbon) or by weathering (such as with phosphorous or calcium).

The atmospheric route is much faster!

Increased transport by stream flow severely disrupts the cycles of elements without a gaseous phase.

(http://www.colorado.edu/GeolSci/courses/GEOL1070/chap04/chapter4.html)

Soil

Formation, Nutrients and cycling, and erosion

Soil is

A mixture of mineral particles, air, water, bedrock, and living and decaying organisms.

“stuff of life” or our “ultimate resource” – heavy dependence on plants in our food chains!

General

A. Soil Size

1. Sand

2. Silt

3. Clay

Soil Properties

Porosity – measure of volume of space that lies between soil particles

Permeability – rate at which fluids move through soils

Water Retention – amount of water soil can absorb

Soil Formation

Weathering Mosses and Lichens --Young soils

rocky, ability to support plant life limited Mature soils take longer time = organic

materials – support growth of many plants

Hundreds of thousands of years may be required to create 10 cm of soil

Five Key factors

Parent material Time Climate Biotic processes topography

Parent Material --Areas of Soil

Bedrock – igneous, metamorphic, sedimentary Source of inorganic material of soil Nutrient richness depends in part on

nutrients stored in bedrock – phosphorus, potassium, calcium, iron, and manganese

Parent rock – area of bedrock that is source of area of soil

Areas of Soil cont.

Soil profile – vertical cross section of soil from surface to bedrock

Horizons – O, A, E, B, C, C – weathered bedrock B – soil receiving materials washed down from

overlying horizons E – pale soil layer mostly sand and silt between A and

B horizons A – Dark brown, made mostly of decomposing organic

matter (commonly known as top soil) O – Dead plant and animal matter (part of top soil)

Time

Can take hundreds of thousands of years to make soil

Climate and Soil

Precipitation Weathering of bedrock High could mean more nutrients being

washed out Temperature

Warm wet conditions cause rock to decay faster

Climate influences nutrient cycling

Nitrogen cycle

Soil pH – power of Hydrogen

A. Measures soil acidity or the hydrogen ion concentration in soil solution

B. pH scale 0-14 0 acid 7 base 14

C. Raise pH Lime Lower pH Sulfur

D. Optimal pH 6-7

VIII. Desirable Plant pH ScaleA. Strongly Acidic Soils (5.0-5.5)

1. Potatoes 2. Watermelon

B. Moderately Acidic Soils (5.5-6.5)

1. Wheat 4. Peanuts 7.Strawberry

2. Soybeans 5. Cotton

3. Corn 6. Oats

C. Slightly Acidic Soils (6.5-7.0)

1. Alfalfa 2. Sweet Clover

Biotic Processes

Includes organic contents Interactions between soil by organisms,

especially decomposers Decomposers are bacteria or fungi that eat

dead organisms, in doing so break them down and release nutrients into soil!

Other burrowing animals allow for water and air to move through the soil

II. Cation Exchange Capacity (CEC)

A. CEC = measure of a soils nutrient holding capacity.- Cation: + charged ions

(attracted to surface of clay – potassium, calcium, ammonium, magnesium)- Anion: - charged ions

(not attracted to clays – nitrate – more readily washed out of a clay soil

B. CEC depends on amounts of clay and organic matter in soil

Topography

Slope and shape of land

Reasons for Soil loss

Deforestation Erosion Soil Mismanagement

Deforestation

Rapa Nui as an example Land is cleared for many reasons

Mining, construction, agriculture,

Deforestation in Madagascar – Reason: cultivation of coffee beans

Erosion: Other Info

A. Two types of erosion

1. Wind

2. Water

a. Three types of water erosion

1. Rill – channels across field

2. Sheet – raindrops remove particles

3. Gully – rills formed together

Erosion

Loss of topsoil by wind or other forces Four categories

very severe erosion- 75% or more and large gullies are present

severe erosion - 75% of soil has eroded but no large gullies present

moderate erosion- 25 to 75% of soil has eroded with small gullies present

none to slight erosion - less than 25% of soil has eroded and no gullies are present

Soil mismanagement

Overgrazing Using Pesticides or fertilizer Irrigation

All leads to “desertification” – most widely noticed near a desert but happening in a wide variety of places!.

Land Improvement

Four common practices to improve arable land Irrigation Erosion Control Drainage Forming (land forming)- surface is smoothed

or reshaped.

Soil Conservation and Land Management/ Sustainable Agriculture

Strip Cropping Contour Farming Terracing Shelter Belt Crop rotation Using less destructive chemicals on

crops Integrated Pest Management

Terracing and shelter belts

VI. Effects of Liming on Plant GrowthA. Correct soil acidity

B. Improves effectiveness and efficiency of fertilizers

C. Reduces solubility of toxic elements

D. Supplies calcium and magnesium

E. Improves biological activity

F. Improves physical conditions of soil

G. Improves yield