The term “invasive species” often has a negative connotation associated with it. Many ecologists assume that “a species invades, and the ecosystem collapses, species go extinct, and complexity and diversity are replaced with a monotonous and weedy landscape dominated by invaders” (97). While some species do destroy ecosystems, exotic species or “invasive species” can actually benefit some ecosystems and species living in the area.
According to Marris, Davis argues that exotic species can help native species flourish by providing more to the ecosystem. He describes that the introduced species can take “over roles once performed by extinct native species” (105). Furthermore, exotic species can create more habitats and landscape. As Davis explains, “[disturbance] create a more variable landscape, with more kinds of habitats, thus increasing the changes that one niche will suit the arrival” (105). The introduced species can also bring new opportunities and availability of food and nutrients. With all these benefits, it is difficult to see why ecologists would even label exotic species as “invasive.”
Marris also points out that there is some bias associated with the type of species considered to be “native” or “invasive.” Ecologists loosely define these two terms. Since they are loosely defined, almost any species can technically be “invasive.” For example, Kristin Saltonstall confirms that the Phragmites is not an exotic species. Instead, it is a global species that exist in places such as America and Europe. However, it ended up being an aggressive species, so it “behaved” like an invasive species (108). While ecologists strongly believe that these exotic species are causing problems, they are already in many ecosystems. Most are already benefiting the ecosystems and it is entirely possible that these “invasive” species are actually native species. Marris points out “the despised invaders of today may well be the keystone species of the future’s ecosystems” (109).
The ecosystems Marris sees in the future are novel ecosystems. Novel ecosystems are essentially ecosystems that have significant human influence, but they can “function as well or better than native ecosystems and provide for humans with ecosystem services of various kinds” (112). Of course, many traditional ecologists reject this idea because this implies that an ecosystem filled with many exotic species can perform better than a natural ecosystem. Despite their beliefs, “novel ecosystems are now more common than intact ecosystems” (114). In addition, these novel ecosystems look remarkably similar to a “normal” ecosystem. If a regular person was to compare a novel ecosystem with a regular ecosystem, it would be extremely difficult to notice any large differences.
Novel ecosystems create many benefits for the native species. This ecosystem provides certain habitats for native animal species if the original content disappeared. Furthermore, it also provides many services such as filtering water and controlling erosion. Marris describes the ecosystem as “vital and energetic” (121) and compared it to human cultures. Again, it is hard to see why ecologists would despise exotic species and novel ecosystems from this list of benefits. Since there are many novel ecosystems around the world, these ecologists should be studying why these ecosystems are successful instead of ignoring them. There will probably be even more exotic species in different areas in the future. The growing number of novel ecosystems around the world makes them “the future of our planet” (122).
