Download Cycles

Cycles of Life
Life and Death, Nutrient Cycles,
Sustainable Development
Nutrient Cycles
Why do the nutrients on the Earth need to be
cycled?
 The Earth is considered a closed system.
 This means that there is little or no input of
new materials from outside the system.
 Organics = H and C, often O and N
(proteins, fats, sugars)
 Inorganics – not containing C and H
 Nutrients can be in the biotic environment or
abiotic environment.
The Carbon Cycle
Plants make carbohydrates through a
process known as photosynthesis.
 6CO2 + 6H2O + E  C6H12O6 + 6O2
 Capture of carbon from atmosphere
Carbon is returned to the atmosphere via
cellular respiration.
 C6H12O6 + 6O2  6CO2 + 6H2O + E
The Nitrogen Cycle
Nitrogen is also very important and it
will also circulate between the biotic and
abiotic parts of the environment.
 Proteins and DNA
Fertilizers contain N, P and K to
facilitate growth
If there is no fertilizer then how does the
plant acquire N?
Phosphorus Cycle
Long and Short Cycles
 Long
 Rocks of the earth’s crust
 Phosphate ions (PO43-) dissolve out of
rocks (due to solubility) and are absorbed
by photosynthetic organisms
 Short
 Living organism’s waste is cycled.
Agriculture and Nutrient
Cycles
Phosphate Accumulation
1. Algae growth = algal bloom
2. Bacteria break down algae and
use oxygen to do so
3. Fish and animals die
4. Problems become worse
Changes in Populations
Changes to populations
 Growth
= natality (birth rate); immigration
 Decline = mortality (death rate); emigration
Limits on Populations
Biotic Potential
 Maximum number of offspring that a
species could produce if resources were
unlimited.
Carrying Capacity
 Maximum number of individuals of a
species supported indefinitely by an
ecosystem. Affected by 4 factors:
Carrying Capacity Factors
1.
2.
Materials and E  amount of usable E from
sun, as well as water, carbon and other
essential nutrients
Food Chains  populations are affected by
populations below (food source) and above
(food source for others)
Carrying Capacity Factors
3. Competition  all individuals in a population
are vying for the same resources
 Intraspecific Competition – same species
 Interspecific Competition – different species
4. Density  only so many organisms can live in
an area at one time
 Density dependent factors – aggression,
neglect of offspring will decrease birth rate
and increase death rate.
 Density independent factors – fire, flood,
extreme weather
Closing the Loop
Sustainable Development
 Ecosystems are sustainable in that they
perpetuate themselves indefinitely and
require little or no additional materials each
year.
 Sustainable development is taking this idea
and applying it to humans
 Development that meets the needs of the
present without compromising the ability of
future generations to meet their own needs