7. Material cycles
• Refer to Topic 1 ppt
Also
• Photosynthesis
• Photosynthesis and respiration
• Carbon cycle
8. Nitrogen in
the air
animal protein
dead plants & animals
urine & faeces
ammonia
nitrites
nitrates
plant made
protein
dead rabbit
decomposition by bacteria & fungi
bacteria
(nitrifying bacteria)
nitrates absorbed
denitrifying
bacteriaroot nodules
(containing nitrogen
fixing bacteria)
nitrogen fixing
plant
eg pea, clover
bacteria
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9. Terminology
Primary productivity – the gain by
producers (autotrophs) in energy or
biomass per unit area per unit time
Secondary productivity – the biomass
gained by heterotrophic organisms
through feeding or absorption
10. Terminology
Gross productivity (GP) – the total gain
in energy or biomass per unit area
per unit time
Gross primary productivity (GPP) - GP
of primary producers
Gross secondary productivity (GSP) –
GP absorbed in consumers
11. Terminology
Net productivity (NP) – the gain in
energy or biomass per unit area
per unit time after allowing for
respiratory losses (R).
Net primary productivity (NPP) – NP
for producers NPP = GPP – R.
Net secondary productivity (NSP) –
NP for consumers NSP = GSP – R.
12. • Would you consider
open ocean or
tropical rainforest to
be the most
productive? Why?
• (consider area)
13. Is this primary or
secondary
productivity?
Gross or net
productivity?
Biomass or
energy?
21. r strategists K strategists
Initial colonizers Dominant species
Large numbers of a few
species
Diverse range of
species
Highly adaptable Generalists
Rapid growth and
development
Slow development
Early reproduction Delayed reproduction
Short life Longer living
Small size Larger size
Very productive Less productive
37. Terminology
Zonation – different to succession –
difference due to environmental
gradient (eg. altitude)
Succession occurs over several seral
stages where each sere is a set of
communities.
Plagiosere – humans prevent a
climax community – growing crops
41. Climax community
• Greater biomass
• Higher levels of diversity
• Better soil conditions
• Better soil structure
• Lower pH
• Taller and longer living plants
• More K less r strategists
• More complexity and stability
• More habitat diversity
• Steady state equilibrium
• Production:respiration ratio P/R reaches 1
(not ideal for agriculture)
44. Evaluating transects
• Same time of day (abiotic and
biotic variables)
• Samples taken througout the year
(seasonal variations)
• Repeat transects for reliable data
(minimum 3 times)
• Random number generator for
where to take transects to
eliminate bias
46. Environmental Impact
Assessments (EIAs)
• To decide if the project will be too
damaging or not, and to mitigate any
damage.
1. Baseline study
2. Monitoring during and after
development
47. Variables in EIA
• Habitat type and abundance
• Species list and diversity including
endangered species
• Land use – access and coverage
• Water flow
• Human population
• Soil quality and fertility
• Example EIA for a dam project