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ecosystems

Discussion of the distribution and abundance of living organisms and how these properties are affected by interactions between the organisms and their environment

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ecosystems

Postby alex08 » Sat Jul 26, 2008 1:20 am

Does anyone know how stable most ecosystems are? Also, are there lots of variables that affect an ecosystem's stability?
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Postby MichaelXY » Mon Jul 28, 2008 8:28 pm

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Postby AstusAleator » Wed Oct 15, 2008 8:24 pm

very good link
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Postby baikuza » Thu Oct 23, 2008 9:29 am

it depends on the how good it's component interacts with the others.

you gave a very good question!

yet, actually i do not know how's the stability of most ecosystem on this earth. but, i know one thing. every single ecosystem do effort to maintain its stability. to do so.. they "evolve" to the more stable ecosystem. savana become forest. primary forest become secondary forest. the most stable is rain forest.

and yes there are so and so many factors that make it stable... believe me! :D
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Postby AstusAleator » Sun Oct 26, 2008 5:04 am

Many people tout biodiversity as the key to ecosystem stability (ie rainforests). Think of a very simple, limited food web with 2 producers, 2 primary consumers, and 2 secondary consumers. Remove one of the species from the equation, and you've got a lot of instability. Now think of a very complex food web with hundreds of species on each trophic level. Remove one species, and the impact is diluted by the presence of all the other species, maintaining relative stability.
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Re:

Postby MichaelXY » Sun Oct 26, 2008 8:16 am

AstusAleator wrote:Many people tout biodiversity as the key to ecosystem stability (ie rainforests). Think of a very simple, limited food web with 2 producers, 2 primary consumers, and 2 secondary consumers. Remove one of the species from the equation, and you've got a lot of instability. Now think of a very complex food web with hundreds of species on each trophic level. Remove one species, and the impact is diluted by the presence of all the other species, maintaining relative stability.


I am not so sure I agree with that. I think biosystems can be rather fragile, and one species survival effects the survival of others. For example, consider the impact if we lost bees.

You might argue the we have butterflies and birds to pick up the slack, but plant evolution has designed itself in such a way that only bees are attracted to certain plant species while others are not.
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Postby AstusAleator » Mon Oct 27, 2008 6:24 am

Yes, there are many factors in ecosystem stability. Biodiversity just seems to be one that people can really get a grasp on. Different species in an ecosystem have different levels of importance to the stability of that system - Keystone species being an example of very important ones.

Still, I think as a general rule, it works pretty well. Do you think there would be as much impact if a species of pollinator was lost in a tropical rainforest rather than the US?

The impact of losing bees would be largely in commercial crops. So that's not an entirely "natural" ecosystem example.
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Re: ecosystems

Postby MichaelXY » Mon Oct 27, 2008 6:37 am

Still, I think as a general rule, it works pretty well. Do you think there would be as much impact if a species of pollinator was lost in a tropical rainforest rather than the US?


Hmm, to be honest, I dunno :oops: but I think I see your point.
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Postby mith » Mon Oct 27, 2008 5:03 pm

Living one day at a time;
Enjoying one moment at a time;
Accepting hardships as the pathway to peace;
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Re: ecosystems

Postby MichaelXY » Mon Oct 27, 2008 8:10 pm

I am aware of what a keystone species is. What I do not know is if the loss of a certain pollinator in a tropical rainforest would have a big impact on the rainforest.

Here is one possible choice.
From internet source.

Because so many plant species, including kapok, eucalyptus, durian, mango, clove, banana, guava, avocado, breadfruit, ebony, mahogany, and cashew trees, depend exclusively on bats for pollination and seed dispersal, bats play a monumental role in the health of the rainforest. For example, bats are the dominant pollinators of forests on remote Pacific islands. Since many plant species on such islands coevolved features to facilitate specific bat pollination, once bats are eliminated there are no other pollinators to fill the niche.

http://rainforests.mongabay.com/0409.htm
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Postby AstusAleator » Tue Oct 28, 2008 12:08 am

Another way to look at stability is to think of stochastic events like landslides or hurricanes. Things that are random, and not density dependant. This would typically not remove a species, but perhaps severely damage the population of one or more species. During the early period of succession and recovery, other species might fill in the gaps and have periods boom and bust, but eventually things will return to relative stability (or not, in which case we have changed selective pressures or relative fitnesses of species in question). More species competing for the early-seral grab-bag diminishes the ripples of the boom and bust effect. Furthermore, the quickness with which a damaged area is repopulated reduces potential additional damage such as erosion.

So in a nutshell: Which would recover faster and more thorougly?
a) A landslide in a South American rainforest
b) A landslide in a Pacific Northwest conifer forest

Getting back to the part about removing species from the equation: This is not something you'll see very often in natural ecological settings, but it is an unavoidable factor to consider in any sort of human-influenced setting. In other words, we're jacking with the system. SO perhaps we need to have two definitions of ecosystem stability; one in natural settings, and one with the human-factor.
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Re: ecosystems

Postby MichaelXY » Tue Oct 28, 2008 6:03 am

So in a nutshell: Which would recover faster and more thorougly?
a) A landslide in a South American rainforest
b) A landslide in a Pacific Northwest conifer forest


You have a presented quite the ecological puzzle, and I have been forced to rub my chin thusly removing certain hair follicles of my face.

On the one hand, we have a less bio diverse area as the Pacific Northwest, on the other we have the vast array of biotic life like the South American forest.

One might think, a catostrophic event in the Pacific Nw would push a ecosystem beyond the brink of recovery.
All the while a bio diverse place such as the rainforest would quickly recover from similar events.

But consider this, The lesser diverse system may lose much of its biological species, however, this condition would also lessen competition for autotrophic species and hetero as well. Those that remained would perhaps quickly repopulate thus restoring the trophic cycle of the region.

The more bio diverse region may lose key populations that maintained balance in the overall system. Loss of the one keystone species, may affect the entire sphere as certain species may end up dominating and thus reduce the overall trophic cycle.

I know, sounds silly, but just thinking out loud. The more I read what I just typed, the more silly I think it is, but since I typed all this BS I am going to hit submit anyways...
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