ECOSYSTEM ECOLOGY

OUTLINE
Ecologicla pronciples related to success of an organism:
Adoptation
Shelford’s Low of tolerance
Liebig Low of minimum
Energy Flows Through Ecosystems
Nutrient Cycles Through Food Webs

Organism have a variety of characteristics that allow them to live in certain environment obtain sufficient quantities scare resources and adapt the change in environmental conditions
Ecological principles related to success of organism are adoptation, tolerance and minimum

Adoptation
Process by which an organism changes to become better suited to survive in their environment. It can also refer to a physical or genetic trait that helps an organism to be better suited to survive in their environment.
Adaptation is powered by natural selection. When a trait arises that allows an organism to better adapt to their environment, it will be passed on to the next generation. Over time this trait will accumulate in the population.

EXAMPLE
For example, polar bears are adapted to living in the cold because they grow thick fur that keeps them warm, and thus allows them to survive in their frigid environment.
The color of their fur is also an adaptation. Because the environment they live in is mostly white, they have produced white fur to blend in, so they are not seen by the prey they hunt

Liebig’s Law of the Minimum - 1840
The distribution of a species will be controlled by that environmental factor for which the organism has the narrowest range of adaptability or control

Liebig’s Law of the Minimum - 1840
Or – the nutrient in lowest supply will set the limit to plant growth

Shelford’s Low of tolerance
distribution of a species will be limited by its range of tolerance for local environmental factors.

How organisms obtain energy
The ultimate source of the energy for life is the sun.
The producers: Autotrophs~ An organism that uses light energy or energy stored in chemical compounds to make energy-rich compounds (Plants-photosynthesis
Autotrophs also are referred to as primary producers.

PHOTOSYNTHESIS
Organisms able to manufacture complex organic molecules from simple inorganic compounds (water, CO2, nutrients) include plants, some protists, and some bacteria.
The process by which they do this usually is photosynthesis, and as its name implies photosynthesis requires light
6 CO2+ 6 H2O à sunlight à C6H12O6 + 6 O2

How organisms obtain energy II
The consumers: Heterotrophs ~ An organism that cannot make its own food and feeds on other organisms
depend on autotrophs for nutrients and energy.
Heterotrophs also are called consumers.

Energy flow
Today we will explore some of the multiple topics related to the flow of energy in ecosystems.

Heterotrophs display a variety of feeding relationships.
Herbivore ~ feeds only on plants
Carnivores ~ kill and eat only other animals
Omnivores ~eat both plants & animals

Heterotrophs display a variety of feeding relationships.
II
Scavengers eat animals that have already died
Decomposers break down the complex compounds of dead and decaying plants and animals into simpler molecules that can be more easily absorbed.

The Process of Primary Production
The general term "Production" is the creation of new organic matter
The plant requires sunlight, carbon dioxide, water, and nutrients, and through photosynthesis the plant produces reduced carbon compounds and oxygen.
Whether one measures the rate at which photosynthesis occurs, or the rate at which the individual plant increases in mass, one is concerned with primary production

Primary Production- the synthesis and storage of organic molecules during the growth and reproduction of photosynthetic organisms).
The core idea is that new chemical compounds and new plant tissue are produced.
Over time, primary production results in the addition of new plant biomass to the system.

So far we have not been very precise about our definitions of "production", and we need to make the terms associated with production very clear.
Gross Primary Production, GPP, is the total amount of CO2 that is fixed by the plant in photosynthesis.
Respiration, R, is the amount of CO2 that is lost from an organism or system from metabolic activity. Respiration can be further divided into components that reflect the source of the CO2.
Rp =Respiration by Plants
Rh = Respiration by Heterotrophs
Rd = Respiration by Decomposers (the microbes)

Net Primary Production, NPP, is the net amount of primary production after the costs of plant respiration are included. Therefore, NPP = GPP - R
Net Ecosystem Production, NEP, is the net amount of primary production after the costs of respiration by plants, hetertrophs, and decomposers are all included. Therefore, NEP = GPP - (Rp + Rh + Rd)
The distinction between gross primary production (GPP), net primary production (NPP), and net ecosystem production (NEP) is critical for understanding the energy balance in plants and in whole ecosystems

The distinction between gross primary production (GPP), net primary production (NPP), and net ecosystem production (NEP) is critical for understanding the energy balance in plants and in whole ecosystems.
Production varies among ecosystems, as well as over time within ecosystems. Rates of production are determined by such factors as climate and nutrient supply.
Precipitation is the dominant control worldwide, but nutrient availability often limits primary production in any particular, local system.

Production and biomass vary greatly across different ecosystems
(Freeman, 3rd ed.)

Who eats Who?

Flow of Matter and Energy in Ecosystems
Food chains: the stepwise flow of energy and nutrients through an ecosystem.
from plants (producers)
to herbivores (primary consumers)
to carnivores (secondary and higher-level consumers
berries → mice → black bear

Trophic levels represent links in the chain
Each organism in a food chain represents a feeding step, or trophic level, in the passage of energy and materials.

Feeding relationships
all food chains
start with energy from the sun
first level of all food chains is plants
most food chains
usually go up
only 4 or 5 levels
all levels connect to
decomposers
Food chains
Fungi
Level 4
Level 3
Level 2
Level 1
Decomposers
Producer
Primary consumer
Secondary consumer
Tertiary consumer
Top
carnivore
Carnivore
Herbivore
Sun
Bacteria

Loss of energy
Loss of energy between levels of food chain
To where is the energy lost? The cost of living!
only this energy
moves on to the
next level in
the food chain
17%
growth
50%
waste (feces)
33%
cellular
respiration

Food webs
network of interconnecting food chains
It is a more realistic view of the trophic structure of an ecosystem than a food chain

Energy and trophic levels: Ecological pyramids
show how energy flows through an ecosystem.
illustrates that the amount of available energy decreases at each succeeding trophic level.
The total energy transfer from one trophic level to the next is only about ten percent because organisms fail to capture and eat all the food energy available at the trophic level below them.
Biomass is the total weight of living matter at each trophic level

As energy flows from one level to the next throphic level , approximately 90% of energy lost

But what about nutrients?
Energy flows through but nutrients cycle
nutrients must be recycled to be available for the next generation
decomposers return nutrients to the soil after creatures die
fungi
bacteria
decomposers

Nutrients cycle around…
through decomposers
soil
producers
consumers
decomposers
potassium
nitrogen
iron
calcium
phosphorus
magnesium
carbon

2006-2007
sun
secondary
consumers
(carnivores)
primary consumers
(herbivores)
producers (plants)
decomposers
Nutrients cycle
Energy flows
soil
soil

biosphere
Ecosystem inputs
constant input
of energy
energy flows
through
nutrients cycle
nutrients
can only
cycle
inputs
energy
nutrients
Don’t forget
the laws of Physics!
Matter cannot
be created or
destroyed

Nutrient Cycling
There are two major types of nutrient cycles
Gaseous – Most of the nutrient is stored in the atmosphere
Sedimentary – Most of the nutrient is stored in the sediments or soils

So what nutrients do we need?
Macro-nutrients are needed in large quantities
Na,Cl, C, H, O, P, K, I, N, S, Ca, Fe, Mg
Micro-nutrients are also essential, but are needed in only small amounts
Mo, B, Cl, Mn, Cu, Zn

Gaseous Nutrient Cycle
The carbon cycle
CO2
plant
herbivore
carnivore
top carnivore
Respiration
Decomposers
(photosynthesis)

Sedimentary Nutrient Cycle
Example: The Phosphorus Cycle
P in rock (apatite)
(weathering)
P in soil
plant
herbivores
carnivores
decomposers
erosion

Carbon Cycle
Carbon and Oxygen combine to form Carbon Dioxide.
Plants use Carbon Dioxide during photosynthesis to produce sugars.
Plants use sugars for plant growth.
Herbivores eat plants, and incorporate molecules into their structure.

Respiration breaks down sugars releasing CO2 and water back into the atmosphere.

•
Inputs to atmosphere currently exceed outputs because of
Small pool of C in air (<1%), so even small changes in inputs can have large effects
• Inputs to atmosphere currently exceed outputs because of human activity

So what nutrients do we need?
Macro-nutrients are needed in large quantities
Na,Cl, C, H, O, P, K, I, N, S, Ca, Fe, Mg
Micro-nutrients are also essential, but are needed in only small amounts
Mo, B, Cl, Mn, Cu, Zn
The elements in yellow have gaseous cycles