Marris has repeatedly brought up this concept of invasive species in her past chapters as an issue for the ecological models she presents. For instance in assisted migration a major issue was whether or not the species migrated would transform into an invasive species, and baseline conservation techniques involved the eradication of all non-native species including invasive species. In these two chapters Marris takes a different approach by showing how invasive species can be assets rather than liabilities. She also continues by explaining in chapter 7 the concept of Novel Ecosystems, which are mainly comprised of invasive species. Her new positive outlook is something that is both of interest and surprise to me, however my main concern is she underestimates the threat of invasive species to our ecosystems.
Marris starts off by challenging this assumption that any introduced species that begins to take over the present organisms in that environment is a negative thing. She makes the point that many invasive species aren’t invasive at all but rather in the long run they serve their purpose and help the environment. For instance Easter Island which once had 50 native species with 7 extinctions now has 111 species after many invaded species came onto its shores. This directly proves the point that “invasions greatly outnumber extinctions [with] the overall diversity of oceanic islands increasing” (103.) The biggest issue is that over the past few hundred years invasive species has been engrained into our heads as a negative features. In Charles Elton The Ecology of Invasions by Animals and Plants, he describes invasive species as “bomb like” and “ecological explosions” (102,) and that goes along with the innate feeling we get when we can “identify opportunities for socially sanctioned destruction” by eradicating invasive species (103.) We have spent an estimated $1.4 trillion, or 5% of the global economy on invasive species. This brings up the next topic of novel ecosystems, which are the “emerging, exotic dominated ecosystems”, that only a few brave scientists “have embraced and given them a more positive name” (109.)
Whether the viewpoint is invasive species are beneficial or harmful, invasive species are still present and are affecting our current ecosystems. These new ecosystems formed through anthropogenic change that are not under active human management are termed novel ecosystems. They are actually “more common than intact ecosystems” (114.) Ecologists believe that these novel ecosystems are equivalent to the previous ecosystem present in that location in terms of ecosystem services and biodiversity. For instance in Puerto Rico, the nonnative trees such as the “flame tree, the African Tulip Tree, and the Mango Tree” are trees that native people have taken into their everyday landscape (113.) The issue with novel ecosystems is that very few ecologists have taken up researching these novel ecosystems because of the idea that all invasive species locations that are like that due to anthropogenic influences aren’t worth researching or saving. Ecologists Erle Ellis estimated a “35 percent of the world’s ice free land is covered with novel ecosystems” (119.) Mascaro worded it well by saying that the preservation and research of novel ecosystems isn’t about “conceding defeat; it is about a new approach” (122.)
I am in complete consensus with this idea of novel ecosystems and the study and research of it because at the end of the day essentially all of earth’s ecosystems are affected by human activities. Instead of using baseline conservation, it seems better to look at what is already present and how we can further enhance that. However I do feel that Marris took this issue of invasive species as a whole too lightly. She did focus on how certain invasive species were helpful, but in general they are a larger problem than she lead them on to be.
