Hoorcolleges Ecologie 2
Hoorcollege 26 april
Gause’s Law – Complete competitors cannot coexist, however complete competition is not
that likely.
Intraspecific competition – happens within a population
Interspecific competition – if you have two species in a community
Facilitation – a positive interaction between two species or two members of an organisms
organisms (positive-negative or positive-neutral)
Elinor Ostrom
Thinking about conservation in a facilitating way
1. Clearly define the commons
2. Adapt to local conditions
3. Establish collective choice agreements focusing on those close to the resource
4. Monitoring by monitors who are part of the community
5. Sanction people who break the rules
6. Make it easy for conflicts to be resolved
7. Allow the user community self-determination
8. Make local users the base level of common pool resource management
The stress gradient hypothesis
As you go up the y-as coemption decreases and facilitation increase.
All the way on the right you have a stressful environment so high competition.
You have facilitation in the middle and competition at the ends. So if there is no benefit in
helping each other, you will compete. But when you are in the middle, there is some stress
so facilitation would be beneficial.
The stress gradient hypothesis
(SGH) provides a framework to predict
when positive or negative interactions
should be observed (8). The SGH
states that facilitation should be more
common in stressful environments,
compared with benign environments
where competition should be more
common.
Due to flood macro pores will collapse making it difficult to transport nutrients. In
intercropping/mix of species it is easier to break apart the soil under flooding and create
macropores, which benefits the whole community.
Facilitation can:
- Enable coexistance
- Increase ecosystem functioning
- Increase germination rates
,There is facilitative and competitive pathway to succession. The species that arrive first are
necessary for the next species; facilitative. The next species can pollinize. They now modify
the environment further. In a competitive way the species arrive that arrive; priority effect.
They try to outcompete who comes second.
Smaller species are experiencing more stress since they cant outgrow the bigger plants.
, Hoorcollege 1 mei – Applying competition and facilitation in practice
There are two x-ases and two y-ases. As we increase abiotic stress we increase facilitation.
If there is increasing stress pest pressure, we also increase in facilitation. Left side is
increasing abiotic stress and right side is decreasing pest pressure.
So abiotic stress is decreasing on the right side of the middle.
Updated stress gradient hypothesis
As you increase abiotic stress you increase facilitation.
See slide on recording
Classical: as we increase abiotic stress we increase facilitation. If you increase pest pressure
also increase facilitation. At bold ends there is an increase in facilitation. In one from
increasing biotic stress in the other from increasing pest pressure. So the x-as is split in half.
At bold ends there is high stress.
If there is too much stress than there is no facilitation.
Competition in conservation
Western honey bee native to Europe and invasive to other continents. However, lots of
decline is also happening in the other bee species. The conservations were focused on the
western honey bee. Wild and native honey bees are often better at pollinating, than the
western honey bee. Therefore, in America it is more dangerous to lose their own native
species. It does not pollinate that well and we need bees to pollinate. However, they are
competitive competitors.
4 strategies to protect bees
Focus on the decline of western honey bee.
1. Plant a bee garden
2. Provide trees for bees
3. Sponsor a hive
4. Support local beekeepers
Hoorcollege 26 april
Gause’s Law – Complete competitors cannot coexist, however complete competition is not
that likely.
Intraspecific competition – happens within a population
Interspecific competition – if you have two species in a community
Facilitation – a positive interaction between two species or two members of an organisms
organisms (positive-negative or positive-neutral)
Elinor Ostrom
Thinking about conservation in a facilitating way
1. Clearly define the commons
2. Adapt to local conditions
3. Establish collective choice agreements focusing on those close to the resource
4. Monitoring by monitors who are part of the community
5. Sanction people who break the rules
6. Make it easy for conflicts to be resolved
7. Allow the user community self-determination
8. Make local users the base level of common pool resource management
The stress gradient hypothesis
As you go up the y-as coemption decreases and facilitation increase.
All the way on the right you have a stressful environment so high competition.
You have facilitation in the middle and competition at the ends. So if there is no benefit in
helping each other, you will compete. But when you are in the middle, there is some stress
so facilitation would be beneficial.
The stress gradient hypothesis
(SGH) provides a framework to predict
when positive or negative interactions
should be observed (8). The SGH
states that facilitation should be more
common in stressful environments,
compared with benign environments
where competition should be more
common.
Due to flood macro pores will collapse making it difficult to transport nutrients. In
intercropping/mix of species it is easier to break apart the soil under flooding and create
macropores, which benefits the whole community.
Facilitation can:
- Enable coexistance
- Increase ecosystem functioning
- Increase germination rates
,There is facilitative and competitive pathway to succession. The species that arrive first are
necessary for the next species; facilitative. The next species can pollinize. They now modify
the environment further. In a competitive way the species arrive that arrive; priority effect.
They try to outcompete who comes second.
Smaller species are experiencing more stress since they cant outgrow the bigger plants.
, Hoorcollege 1 mei – Applying competition and facilitation in practice
There are two x-ases and two y-ases. As we increase abiotic stress we increase facilitation.
If there is increasing stress pest pressure, we also increase in facilitation. Left side is
increasing abiotic stress and right side is decreasing pest pressure.
So abiotic stress is decreasing on the right side of the middle.
Updated stress gradient hypothesis
As you increase abiotic stress you increase facilitation.
See slide on recording
Classical: as we increase abiotic stress we increase facilitation. If you increase pest pressure
also increase facilitation. At bold ends there is an increase in facilitation. In one from
increasing biotic stress in the other from increasing pest pressure. So the x-as is split in half.
At bold ends there is high stress.
If there is too much stress than there is no facilitation.
Competition in conservation
Western honey bee native to Europe and invasive to other continents. However, lots of
decline is also happening in the other bee species. The conservations were focused on the
western honey bee. Wild and native honey bees are often better at pollinating, than the
western honey bee. Therefore, in America it is more dangerous to lose their own native
species. It does not pollinate that well and we need bees to pollinate. However, they are
competitive competitors.
4 strategies to protect bees
Focus on the decline of western honey bee.
1. Plant a bee garden
2. Provide trees for bees
3. Sponsor a hive
4. Support local beekeepers
