Organisation at the Ecosystem Level 75
may help the ecosystem to overcome relatively small perturbations in a generally predictable environment. Complexity, however, is a fragile state that
becomes possible mainly because of the environment’s stagnation. Complex
bations that surpass their normal experience. A non-predictable environment requires a rather simple and robust ecosystem.
The connection of diversity or complexity with the stability of eco systems
has been discussed for many years. The thesis of connection has been based
on various observations and arguments, summarized as follows:
• The simple mathematical models of predator-prey end up in non-stable
systems.
• Laboratory experiments with simple predator-prey systems usually
end up with the extinction of the first or both species.
• Small islands’ ecosystems (that are relatively simple) exhibit small
resistance to the introduction of new species.
• Population explosions happen more often in single-crop farming and
less often in more complex ecosystems, whereas no population explosions are observed in tropical forests.
• Parasites create more serious problems to cultivations where many or
strong pesticides have been applied.
• Ecosystems in northern and arctic areas exhibit great oscillations (possibly because their complexity is not great enough to eradicate them).
Theoretical and experimental ecologists, however, have developed many
counter-arguments that can be summarized as follows:
• The simple mathematical models of population dynamics are not
stable , but the more complex ones are even less stable.
• There are natural “single-crop” systems (e.g. marshy coastal vegetation) that are very stable.
• The most significant parasites that present population explosions
(locusts, rodents etc.) have a great variety of enemies.
• Islands do not exhibit lack of stability; they are simply more vulnerable. There are complex systems as well that are vulnerable (i.e. forest
destruction due to the chestnut’s parasite).
• The stability of the coral reefs’ complex ecosystem (aquatic equivalent
to the tropical forest) was hard hit by the invasion of a starfish species.
• Natural ecosystems, complex or not, are products of a long-time
co-evolution of their populations. Evolution managed to find the,
perhaps small, parameters’ space that give long-term stability to the
system. Thus the comparison of a tropical forest with an agricultural
system is not relevant, because a natural system, which is a product of
a long evolution, is compared with an artificial one.
may help the ecosystem to overcome relatively small perturbations in a generally predictable environment. Complexity, however, is a fragile state that
becomes possible mainly because of the environment’s stagnation. Complex
bations that surpass their normal experience. A non-predictable environment requires a rather simple and robust ecosystem.
The connection of diversity or complexity with the stability of eco systems
has been discussed for many years. The thesis of connection has been based
on various observations and arguments, summarized as follows:
• The simple mathematical models of predator-prey end up in non-stable
systems.
• Laboratory experiments with simple predator-prey systems usually
end up with the extinction of the first or both species.
• Small islands’ ecosystems (that are relatively simple) exhibit small
resistance to the introduction of new species.
• Population explosions happen more often in single-crop farming and
less often in more complex ecosystems, whereas no population explosions are observed in tropical forests.
• Parasites create more serious problems to cultivations where many or
strong pesticides have been applied.
• Ecosystems in northern and arctic areas exhibit great oscillations (possibly because their complexity is not great enough to eradicate them).
Theoretical and experimental ecologists, however, have developed many
counter-arguments that can be summarized as follows:
• The simple mathematical models of population dynamics are not
stable , but the more complex ones are even less stable.
• There are natural “single-crop” systems (e.g. marshy coastal vegetation) that are very stable.
• The most significant parasites that present population explosions
(locusts, rodents etc.) have a great variety of enemies.
• Islands do not exhibit lack of stability; they are simply more vulnerable. There are complex systems as well that are vulnerable (i.e. forest
destruction due to the chestnut’s parasite).
• The stability of the coral reefs’ complex ecosystem (aquatic equivalent
to the tropical forest) was hard hit by the invasion of a starfish species.
• Natural ecosystems, complex or not, are products of a long-time
co-evolution of their populations. Evolution managed to find the,
perhaps small, parameters’ space that give long-term stability to the
system. Thus the comparison of a tropical forest with an agricultural
system is not relevant, because a natural system, which is a product of
a long evolution, is compared with an artificial one.