why are invasive species an environmental concern?
373933
Since they have no natural predators, they take over the environment.  This happens because the addition of this new predator throws off the balance of the ecosystem, sometime fataly.
583543
Because Mangroves provide nursery grounds for\nfish, prawns and crabs, and support fisheries\nproduction in coastal waters. Almost\nevery living thing needs a safe place when it is\nyoung, small and fragile.
237532
if the environment changes faster than the organisms ability to adapt to the changes, the species will go extinct. The reason, be it man made, or natural, is irrelevant. The point is, there is a change, and the organism cannot adapt.
888046
I guess I am not allowed to answer since I am concerned about global warming.  I am also concerned about the massive population explosion of dim wits.  Both are great causes of concern.  But since you did not ask for solutions I will not give you what you did not ask for.  You seek to get blabble babble static and drivle...
104356
Keeps the population of other species in check.
894008
Yes, the ambience is quite congenial for animal living. The rare species among them are being propagated within the ecological limitations.
591296
With many declining populations, there are no hard numbers available.  Because the organisms are very rare, it is often difficult to tell exactly how many are left in the wild without doing extensive surveys, and there simply isn't funding to track the populations of all endangered species that closely.\n\nWith other species, there are conservation programs in place, and populations are monitored as closely as possible.\n\nA good place to start to find information on specific endangered species is the IUCN (World Conservation Union) Red List of Threatened Species.  Their web-site can be found at http://www.redlist.org/info/introduction
1179874
(1) There are several factors which make environmental problems. Some of them are mentioned below for your knowledge.\na) Overcrowding, poor-quality housing\nb) Inadequate provision for water supply\nc) sanitation factors\nd) Different pollutions( air, water, land)\ne) Deforestation\nf) Smoke from vehicles and  factories\n\n(2) In addition to that, secondary impacts of the above mentioned factors are also make environmental problems.
613867
As is typical, loss of habitat is the greatest concern for AT as well as other special biomes.  For example, the polar bear has a yearly cycle in northern Manitoba and Ontario, in which it goes out onto the ice cover of the Hudson Bay in the fall to hunt, and returns in the winter- Recently, the freeze/thaw cycles have changed, and many of the bears are starving or being trapped on the ice.  Efforts are being made now to provide food and chase them off the early-thawing ice with helicopters, but obviously if the trend continues, it's likely a losing effort.  If the challenge is changing weather patterns, there isn't very much we can do, other than try to minimize the climate changes.  Other challenges include development of the area, especially for oil and coal exploration, which might seriously disrupt migration patterns of the large prey animals.  In general, though, the arctic tundra is not among the most threatened habitats, and so is not focused on as much as, for example, wetlands, rainforests, and coral reefs.
185450
I think you said it best first: a weed is just an unwanted plant.\n\nDon't believe that crap about a weed just being a plant we haven't found a use for.\n\nI'm a restoration ecologist and I have seen weeds destroy more biodiversity and habitat than ANY other cause.\n\nEDIT: myrtguy: you usually have good answers on these issues but they may be a little misleading here.  Restoration ecologists do a lot more than just working on areas that humans have made a mess of (though you are right - that is mostly what they do).  It is worth mentioning that you would be hard pressed to find ANY area of land that has not been influenced by humans to one extent or another.\n\nYou are also right about plants in gardens but... Many of our most agressive weeds are plants that have escaped from gardens unintentionally (such as Purple loostrife or Leafy Spurge).  Too many nurserys sell these things to coustomers who transport them all over the U.S. (and the world).
560087
Protect and respect their habitats.  Help wildlife by building a bird feeder, composting, eliminating the use of pesticides and herbicides, etc.  In your garden use plants native to your area - do not introduce plants that are not native - they may disrupt the natural balance. \n\nPossibly one of the best things we can do is stop demanding so much of the world's resources, which, in one way or another, destroys wildlife habitat - increases global warming, destroys the rain forest, etc.  Use cloth reusable shopping bags to carry home groceries.  Buy at bulk food stores using much less packaging materials.  Recycle as much of what we use as possible - glass, soda cans, food cans, plastic containers, newsprint, etc.  Recycle toys, books, games, clothes, etc. by donating them to goodwill or Salvation Army, and shop for things you need at those stores.  Live a simpler, gentler life style.  \n\nHere are a few sites you may like to view.
219546
In relation to Environmental issues in Denali. From a personal perspective I'd have to say encroachment from the human species.All along the park entrance business's hotel's,shops and restaurants are being built.Then on top of that the number of climbers has increased over the years. So much that the park service is now limiting more the permits for climbing denali. As far as humans inside the park. It has been fairly much controlled by severely limiting the amount of vehicles allowed on the park road.Now as far as just things affeting the environment I would probably say global warming and smoke from regional fires are about the only things I know that might be affecting the area.Glacial retreat may be a problem in the future. Check out the site below for more
1082351
Necessary for who?  It is certainly necessary for humans.  If it wasn't for humans, humanity in general wouldn't exist.  Maybe the rest of the planet might not miss us much, but I certainly would.\n\nWhile our presence and proliferation certainly does have a detrimental effect on many other organisms and ecosystems, it is because we create our own ecosystem.  Not many people really think about, but human cities and even rural developments have their own ecology and associated plant and animal life that thrives in contact with humans.\n\nSpecies such as rats, cockroaches and pigeons are the obvious faunal assemblage associated with human activity, but there are other species of animals that have become far more successful in association with humanity than they would otherwise have been.  Cats and dogs are far more numerous and widespread than their wild counterparts, as are chickens, sheep, cows and all of our domestic animals.\n\nThe crop species, like wheat, corn, rice and other have also benefited immensely from human cultivation.  The wild counterparts of broccoli and banana are not nearly as successful.\n\nThere are also species who have been able to expand their range as the human ecosystem pushes competitors farther afield.  Coyotes, raccoons, opossums, tree squirrels, house sparrows, starlings, and even white tailed deer have all benefited as the human ecosystem takes over what was formerly plains or forest ecosystem.  Other species like elms, palm trees, oaks and ash used to line our city streets have also expanded their range.\n\nWhile it's not exactly great for biodiversity, the human ecosystem does certainly benefit some organisms.  Without us Plasmodium (the protozoan that causes Malaria) wouldn't be nearly as successful as it is.\n\nSo the Earth itself would certainly survive quite nicely without us, but that entire ecosystem of cows, wheat, cockroaches and kitty cats would be wiped out without us.  In many ways, we are a keystone species in our ecosystem.  It's just too bad that we seem to be insistent on replacing EVERY other ecosystem with our own.
1038295
The natural environment is full of wide sparkly rivers and waterfalls and lushes green plants with a plentifly amount of animals.So behind all that there is hurt. Animal populations are low. Plants are be torn down.And the water is getting trashed.
1087763
to keep species of plants and animals from going extinct and to educatethe public
895154
Species are dying out all the time. And this effects the ecological balance. Therefore conservation biology can help to maintain species and prolong others lives. This is a must in research otherwise there will be nothing to research.
1156545
In general changes to the DNA of a species poses a risk of unexpected results.  Nature is generally in more or less of an equilibrium.  When sudden changes occur that balance can be upset.  Like when new predators are introduced into an area and their prey is wiped out.  Or when a plant is introduced to a new area and spreads uncontrollably.\n\nCreating "new" plants can have the same kind of impact as moving plants around from one part of the world to another.\n\nAdditionally there is some concern that taking DNA from one plant and embedding it in another plant's DNA (e.g. to improve resistance to insects, drought, etc.) could have adverse effects (e.g. producing allergic reactions where none had existed).\n\nThere's no right answer.  As with any technology we have to weigh the total impact (on humans, the environment, etc.).