Structure of course
Environmental variability
Organisms
Ecosystems
Populations
Species interactions
Communities
Applied Ecological Issues
1
Outline for ecosystems
Introduction
How does energy move through an ecosystem?
How does matter move through an ecosystem?
2
Ecosystem – communities of organisms and
the physical and chemical components of their
environment
Ecosystem approach – focus is on movement
of energy and matter through different
compartments of ecosystems
3
Questions asked by ecosystem ecologists
How productive are ecosystems? What
controls their productivity?
How are primary and secondary productivity
related?
How are nutrients transformed and cycled in
ecosystems?
4
Ecosystem services / ecosystem functions
-processes carried out in ecosystems that
benefit humans
- e.g., food production, nutrient regeneration,
degradation of pollutants, erosion control
5
Ecosystem Management
- process of sustaining ecosystems, their
processes, and the services they provide
for future generations
6
Ecosystem Management
1. People must manage ecosystems
2. Ecosystem processes and services can
be reasonably self-sustaining under some
but not all management regimes.
3. Future generations deserve access to the
same ecosystem services as we have.
7
Outline for ecosystems
Introduction
How does energy move through an ecosystem?
How does matter move through an ecosystem?
8
energy stored
in reduced carbon
compounds
energy from
sun
9
Figure 6.3
= energy lost
Net production
Gross
production
Biomass = stored energy
10
Figure 6.8
11
What controls net primary productivity?
temperature, light, nutrients, water
12
Figure 6.8
6.7
13
Net photosynthetic efficiency = percentage of
energy from sunlight that is converted to net
primary production.
14
How efficient are photosynthetic organisms?
1 – 2 % efficient
What happens to rest of sunlight?
25-75% is reflected
rest is absorbed by no photosynthetic molecules
15
What happens to net primary production?
-eaten while alive – herbivores / omnivores
-eaten after death – detritivores
-buried
-burned
energy moves with biomass
16
Figure 6.2
Herbivore
Carnivore
Herbivore
17
Trophic pyramid
Figure 6.1
Tertiary
consumers
Secondary
consumers
Primary
consumers
Primary producers
18
Ecological/food chain efficiency = the
percentage of energy in the biomass produced
by one trophic level that is incorporated into the
biomass produced by the next higher trophic
level
What determines efficiency?
19
Ecological/food chain efficiency = exploitation
efficiency x gross production efficiency
Exploitation efficiency = amount of net production
ingested by next level
Gross production efficiency =
net production/ingestion x 100
20
Gross production efficiency
Warm-blooded terrestrial animals <5%
Insects 5-15%
Some aquatic animals 30%
21
How fast does energy move through
an ecosystem?
Biomass accumulation ratio =
biomass / rate of biomass production
22
standing biomass
biomass production rate
Figure 6.13
lowest
on
land
23
Ecosystem Management
- process of sustaining ecosystems, their
processes, and the services they provide
for future generations
- example of Lake Mendota
24