Is all conservation good?

[chrissie]

i think that when man is involved in the endangerment of a species then we should help it to recover as long as it doesn't unbalance the ecosystem in which they live, but when it is just a natural decline in numbers then it should be left to good old mother nature to decide.

what do you all think?

also which is better:

species conservation; or

ecosystem conservation.

[natterjack]

Nowadays it's fairly difficult to find an example of "natural decline in numbers" that may not have been influenced by human activities. There is basically nowhere on the planet where some amount of anthropogenic pollution of air, water, soil etc can't be found. And then there is climate change. If humans have a hand in that - and I certainly think that we have - then there are very few habitats that will escape human induced change which could influence population numbers one way or another. This is not to say that we are responsible for all declines, just that it's difficult to tell which we are responsible for.

Ultimately, of course, all species are pretty much bound to become extinct, that's the way it works.

As for species or ecosystem conservation being "better", well it depends what you mean by better - a question that has occupied philosophers for some millennia. Better for whom, and to what end?

Generally, if you look after the ecosystem, the species will look after themselves, but then of course, you may need to do something specifically for a few "keystone" species (if you accept the idea of keystone species) to conserve the ecosystem in the first place.

Just concentrating on the ecosystems, though, may mean that a few species are lost - which I'm sure that members of that species would not consider "better", and if you think that all species (or even individual organisms) have an innate worth, maybe you should be concentrating on the species.

Or perhaps we should think about "better" from a human perspective - but even then, it could be that the one species that's lost was the one that holds the only key to a revolutionary new anti-cancer drug or whatever. But then perhaps just keeping DNA samples from everything would allow for that. It would almost certainly be more economical.

[reality]

I think the best thing you said there was that we're looking at it from a human perspective.

I'm sure if we save a species and you're an animal that the saved species likes to eat you wouldn't be quite as grateful

[chrissie]

some very good answers and i am not going to argue with any of them, but if we concentrate on just one species it could upset the whole balance of the ecosystem. if it is a predator, then the species it preys on would decline as the preditor numbers increase, which will cause a chain of reactions which would upset the whole ecosystem in the end as everything is linked. (this is only a worst case scenario)
But if you conserve an ecosystem as a whole then maybe a few species will be lost from that area along the way but maybe it would be for the greater good so that most of the ecosystem would still be there.

[natterjack]

Originally Posted by chrissie

if we concentrate on just one species it could upset the whole balance of the ecosystem. if it is a predator, then the species it preys on would decline as the preditor numbers increase, which will cause a chain of reactions which would upset the whole ecosystem in the end as everything is linked

Yes - as you say this would be a worst case. Actually, although it does happen, the number of cases where a predator has been shown to have been solely, or mainly, responsible for the drastic decline in their prey species is relatively small (excluding introduced species, which is a different matter altogether). Here we're talking about deliberate intervention on behalf of the predator, but concentrating on conserving a predator would really have to involve ensuring a good food supply for it.

If you're concentrating on keystone species, basically they're not going to be predators anyway - predators are a bit of a luxury in that sense.

[foxfire4321]

Most of this discussion surrounds the bigger question of how much of what we claim to conserve is natural in the first place.

I know the situation in the United States is confusing to say the least, given the human and introduced species impact on the environment, but I imagine it has to be at least an order of magnitude more confused in Europe, where human intervention has a much longer history.

I favor the preservation of ecosystems and species diversity, but can't say that all introduced species or the loss of each "native" species has a measurable negative effect on these ecosystems.

[natterjack]

Yup, Foxfire, it certainly is more confused over here!

The general concensus is that there is nowhere in the UK (and precious little on the continent) that is untouched (disregarding climate change and pollution for a moment - I mean physically altered) by humans. Deforestation for grazing back in the neolithic and bronze ages, and quite probably large scale fires to create good hunting grounds back in the mesolithic, were the first major impacts, and everywhere: upland moors, lowland heath, woodland - the lot - has been exploited pretty intensively since. However, the forms of exploitation have been pretty consistant through time until the 20th century, and a semi-natural community of species has evolved in each case to cope with it. This is generally what we are conserving over here now.

A distinction is often made between conserving and preserving - which can only be done to a basically untouched ecosystem that's just changing at its own rate. There are a few areas of the US where preservation is still the aim, such as Yosemite etc, but they're getting rarer.

I agree that not every loss or introduction has much of a negative effect: A great number of the species introduced to the UK throughout its history of exploration, trade and empire have become fully integrated into the ecosystem, but typically so little is known about any species lost or introduced - and its interactions - that the consequences can't be reliably predicted beforehand.

[foxfire4321]

This brings up the interesting question of whether an ecosystem can be healthier with the intervention of human or introduced species as opposed to its pre-introduction state. One of the famous examples in the US is kudzu, a lovely Japanese vine that was introduced to the US Southeast in the late 19th, early 20th sentury. The vine grows like wildfire (up to two feet a day) and is obviously a nuscience, but it has succeeded at its original mission which was to slow soil erosion. So here we have an intorduced species that obviously grows well in the ecosystem, competes effectively (though has not been shown to destroy any resident populations to extinction), and serves a valuable, if annoying (trust me it is annoying the first time you come back from holiday and have to cut your car out from under the stuff) function. Is this something that has made the ecosystem healthier or worse?

[natterjack]

Healthier or worse...

Well it depends how you measure healthier.

You could measure it by overall biological productivity (sounds like kudzu would be good that way) or you could measure it by diversity. Now there are actually two measures here -

1 Total number of species
2 relative numbers of these species.

Total number of species: well again, if nothing has gone extinct, kudzu looks to have improved the situation. By the second measure however, I'd guess that it probably hasn't done too well for the ecosystem. It sounds like it is likely to have become the most abundant plant by far in a lot of places, if it's that productive. So although the other, original, plants are still there, they're going to form a much smaller proportion of the total number of plants around. From there, it's likely that anything that can eat kudzu will be doing quite well, and things that rely on the other plants, not so good. If this has happened, and it's getting to dominated by one or a small group of species, then the ecosystem is not truly as diverse.

But that's only one part of the story.

If this is the only place where kudzu is a major component of the community of species, then it could add to the overall range of habitats around, and so maybe add to diversity on a larger scale, but if this is happening in a lot of places, and sizable parts of the country that previously had individual characters and communities are starting to be dominated by the same plant, then the overall diversiy of habitats is going down.

There are several introduced species that have done, or are doing, just that here in the UK.

Ultimately, whether it got there by human hand or under its own power, any species in an ecosystem was a newcomer once and would have altered its environment.

It was, a while ago, common to talk of "pioneer communities" and "climax communities" ie the first species to colonise bare rock and the "final" groups of species (mature woodland, often), but nowadays this is thought to be a bit outmoded. Any species will be continuously altering its surroundings to a greater or lesser extent, and so quite probably creating a niche that wasn't previously there that something else can take advantage of, while at the same time making life more difficult for something else. The general trend, however, is that the longer a particular community has been around, the more complex and diverse it will be.

When a species is introduced artificially however, if it's sucessful it's because it's lept straight into a niche and is outcompeting one or more existing species, but probably won't replace all the interactions with other species that the existing one participated in. and the established, complex, ecosystem a with great many interactions will start to become more simplified, with the specialised species going under first. As the interactions fail, similar, simpler, and smaller collections of opportunist species take over in a range of habitats time and again.

It's not really that introduced species are inherently bad, its just the rate of change that they tend to produce that counts: It doesn't allow time for new complex communities to form.

[LeeP]

Kudzu is an equal opportunity destroyer. It destroys whole forests, whole ecosystems. The reason that it hasn't driven any resident population to extinction (if it hasn't, and we don't know that) is that we have been fighting it aggressively since the 50s. To posit that it has made any ecosystem healthier, fox, borders on insanity. When you have an ant problem, do you use an A-bomb to take care of it?


Lee