Example of a case study : When the "Grey wolf" was reintroduced into the Greater Yellowstone Ecosystem in 1995, there was only one beaver colony in the park, said Doug Smith, a wildlife biologist in charge of the Yellowstone Wolf Project. Today, the park is home to nine beaver colonies, with the promise of more to come, as the reintroduction of wolves continues to astonish biologists with a ripple of direct and indirect consequences throughout the ecosystem. Cases of how the re-introduction of wolves , changed the river patterns significantly, is also a remarkable study!
http://www.yellowstonepark.com/wolf-reintroduction-changes-ecosystem/
Just a word of caution on terminology:
Reintroductions and Introductions are two very different issues: the former indicates the release of a taxon to an area where it was present in earlier - historical - times and later got extinct, whereas the latter indicates the release of an alien (allochthonous) taxon to a new area. The release of wolves to Yellowstone has been a reintroduction, but the release of South American coypus and North American grey squirrels to Europe or that of red foxes to Australia have been introductions. The former are positive operations - if properly conducted - and tend to restore pristine zoocoenoses, whereas the latter are quite negative operations as they tend to upset ecosystems.
In both cases you should expect consequences on the ecosystems, usually favourable in the first case, nearly always negative in the second case. The effects of weather and climate integrate with these consequences (or rather the other way round!).
Universally it is not possible. However, rarely it can happen as you have mentioned the example of Grey Wolf.
Factor influencing season is mostly abiotic, i.e. pressure/temperature difference between two continents or oceans.
Climate could change if the extend of introduction is great enough to change the vegetation. However, usually it is unwanted, because novel climate creates problems for native organisms adapted to original climate. Vegetation cover significantly influence hydrology. The effect is obvious in deforested area, which suffering from lower water table and drought, and in desertified area, where the loss of vegetation cover causes unstoppable further erosion of the soil, forming dust-storms.
You could argue that the answer is "no". The basis for this would be that based on the rather open ended definition of "niche" each species occupies one an only one "niche". Since an introduced species would be occupying a unique niche it would not change the nature of the unique set of parameters that are relevant for that species.
I am not an expert on ecology of communities, but if you introduce a species to a habitat where there are no predators for it, certainly the ecological dynamics will change. However, for changing seasons and climate you need much more than the introduction of species. Climate is not easily changed, it will take decades for having a slightly variation. I do not see any correlation between introducing a species and changing seasons or climate. Hope it helps somehow. Cheers.
Introductions cannot change the ecological nature of seasons and climate, but they can change the effects of seasons and climate.
If the introduced species successfully alter a fundamental portion of the trophic chain, as it would be the case of apex predators, like the grey wolf you mentioned, it may cause substantial changes in the host ecosystem structure in the long term; but mostly the introduction of a single species should not promote global changes...
Just a word of caution on terminology:
Reintroductions and Introductions are two very different issues: the former indicates the release of a taxon to an area where it was present in earlier - historical - times and later got extinct, whereas the latter indicates the release of an alien (allochthonous) taxon to a new area. The release of wolves to Yellowstone has been a reintroduction, but the release of South American coypus and North American grey squirrels to Europe or that of red foxes to Australia have been introductions. The former are positive operations - if properly conducted - and tend to restore pristine zoocoenoses, whereas the latter are quite negative operations as they tend to upset ecosystems.
In both cases you should expect consequences on the ecosystems, usually favourable in the first case, nearly always negative in the second case. The effects of weather and climate integrate with these consequences (or rather the other way round!).
In every ecosystem there are enablers and constraint factors which help keep the population of individual species in balance with the rest of the biotic and abiotic factors. As already stated, when a new species is introduced into an ecosystem where enabling factors are in abundance, with less inhibiting factors, chances are that its population will over time offset the balance of that ecosystem in a way that might lead to changes in the climate.
Dr Sandro Lovari has elegantly analysed the issue. I fully agree with the answers given by him.
Your question is a bit unclear as it is unlikely that an introduced species would occupy (or create for that matter) a completely new niche. That said, introducing a new species will likely result in overlap among some niche dimensions between it and organisms that occur in the ecological community to which the new species is introduced. Because of this, there are many circumstances where the consequences of climate change or season could be exacerbated by such an introduction. The one that comes to mind is the availability of food resources and a species introduction could reduce the variety of amount of food resources available to members of the existing community which already is being impacted by climate change or seasonality. Availability of refuges from predation or extreme temperatures is another that could be influenced.
An introduction could have an impact(s) on an ecosystem and humans will make a judgement call if that will be a positive or negative impact(s) based on criteria that could be the subject of debates. Impact(s) on a particular ecological niche is more questionable, depending on what you call a "particular ecological niche". Now, "introduction changing the ecological nature of seasons and climate"??? Would it not be the other way around, with seasons (timing) and climate having an impact on the success, or not, of the introduction? And if the climate is changing, then, the response could also change... but that could be for another debate!
Upasona
I think Sandro Lovari explain your quarry in a very lucid way and I hope there is nothing to be added with his explanation. I am absolutely agree with Dr. Lovari.
With Regards
Sunit
Upasana,
If perhaps you were looking for examples of non-native species that have had large ecosystem level effects, a good example is cheatgrass (Bromus tectorum) which occupies millions of acres in the western USA. Because of its physiology, it has increased the frequency of the fire disturbance regime for this region. It burns with increased frequency and intensity now.
Kenneth, I guess that Winston meant: "existing community which already is being influenced by climate change or seasonality." Am I right?
As for Upasana's question, it may have not been properly formulated, i.e., "ecological nature of seasons and climate" (!?), but it has open a very interesting debate, thanks Upasana!
Very interesting question! Leaving aside the value issues of "good" or "bad", I think the answer is yes.
A case in point is the expansion/invasion of cheatgrass (Bromus tectorum) over large areas of the western US. Cheatgrass generally greens up much earlier than native grasses, sufficiently so that this can be detected via e.g. MODIS NDVI signals. I've heard that cattle ranchers sometimes prefer to have some of their grazing lands "infested" (my value-laden description!) with cheatgrass because this can provide very early-season, nutritious forage, presumably for both domestic and native herbivores.
Since phenology is an index of seasonality, it seems reasonable to argue that this is an example of an introduction that has led to, or contributed to, early spring in some ecosystems. I suspect there are many other examples along this line of thought - species introductions/expansions where the phenology of the "new" species is outside the range of the native species.
An example in Madagascar, is the disaster cause by the introduction of alien fishes species in freshwater biotopes: most of endemic fishes are suffering in short period of time in ecology and biology frame (about 20 years!!).
However, like some answers above, the reintroduction of an endemic tortoise with significant declining populations inside the reserve it was originated, did well.
Observations about pigs and forests in France may offer something. Different from the idea that pigs, being forest animals, contribute to desertification in the Middle East. http://crueize.com/doc/PigsInTheForest.htm
I completely agree with answers of the previous experts. New introduction of types practically always has negative result. Repeated introduction of the types which are earlier lost usually has positive result. An example of reintroduction of muskoxen in America and Russia, in Greenland.
New introduction of types or acclimatization and introduction therefore negative results - rabbits in Australia were received, domestic cats on Tasmania, such examples a huge number worldwide.
At least at microclimate level, changes due to introduced species may be significant. An example from central Europe: Banks and gravel bars of streams and rivers are frequently colonised by a handful of introduced species (e.g., Reynoutria japonica, R. sachalinensis, Impatiens glandulifera, Solidago canadensis...). Communities formed by these very competitive plants differ from natural vegetation not only in species composition, but also in cover, texture, growth, phenology etc. Their impact on humidity, temperature, light intensity etc. at ground level, compared to natural vegetation plots, is readily identifiable. These effects may impact habitat availability, habitat use and seasonal pattern of other native species, too (nectar-feeding insects, gravel-breeding birds, ground beetles...). Besides that, root systems of certain species (Reynoutria spp.) can destabilize river banks - with further effects on local habitat structure and patch dynamics.
...and flowering stands of Impatiens glandulifera smell so importunately soapy - an annoyance if you go fly-fishing....;b)
Kenneth, that's the point, sadly. By the way, lifestock (pig, cattle) fattening at wood pastures was common practice over centuries in European broad leave forests. It caused the formation of "Hudewald", half-open woodlands with big old oaks. Despite being cultural landscape elements rather than natural ones, the remainders of "Hudewälder" may be hot-spots of conservation nowadays. And the genetic heritage of early cultivated pigs is still roving around in our wild boar populations - up to 3% or so of their individuals are not uniformly dark, but pied like early domestic pigs (see video clip, from 00:30s).
This phenomenon really affects the ecosystems to some extinct. Factory farming is resulting in invasion of some plants and pest species in other ecosystems. Some are really harmful and alarming.
I hate to destroy your Yellowstone story - but the beavers were actually reintroduced at about the same time as the wolves - so they would probably have come back anyway.
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