It would seem that when an “invasive species” enters an ecosystem, they would cause native species to go extinct because of the new competition for food and space, or because the native species would become prey. However when an invasive species of trees were brought to Rodrigues Island, they were able to bring back three species of animals that were soon to become extinct. Though these trees helped the island, they were still cut down by environmentalists because they were “invasive” and not a part of the baseline economy.
It has been a misconception that invasive species cause harm to their new environment. Many actually have no impact, and some are actually helpful. There are some invasive species that have been a nuisance and caused damage like the Zebra Mussels, but cutting down the trees in Rodrigues Island was a real waste of time and money. Rather that effort should be put in to remove the invasive species that are causing real damage.
Dov Sax said that invasions actually bring about diversity to many oceanic islands, however this idea can be a little misleading. With the advent of human arrival to islands like Easter Island, 68 more plants had been introduced, increasing the diversity of the island. Though 7 species of animal went extinct, which defeats the purpose of diversity, he brings up the fact that the extinctions were not caused by the introduced species on continents. I really like the idea of bringing exotic species into nonnative ecosystems in order to help clean up and regulate them. I didn’t know this was a possibility, but this type of introduction of species shows us how assisted migration can also be beneficial.
In the seventh chapter, Marris talks about a type of modern ecosystem that many ecologists have overlooked, the Novel Ecosystem. It is a “new, human-influenced combinations of species that can function as well or better than native ecosystems and provide for humans with ecosystem services of various kinds—from water
filtration and carbon sequestration to habitat for rare species.” Though this type of ecosystem seems unorthodox, Marris points out how beneficial they can be, and also that nonnative species are able to thrive amongst each other. This shows us that species are able to find their own niches in time, and create a stable system that could easily be mistaken for as native. However this idea seems very unlikely, and the only reason I can believe it is because of the evidence that Marris provides.
If the novel ecosystems do work, since most ecologist do not know its future and how it will progress, it seems that one of ecologists greatest dilemmas will be solved; if you give time to an environment with nonnative species, it will” work itself out. ” I am still weary of this idea because some invasive species, especially the Zebra Mussel does not seem like it will get better any time soon. Marris does say that ducks are eating them, however, we do not have an infinite supply of ducks to eat them.
