Aquatic Invasive Species

Scientists often use war metaphors to describe invasion biology and their efforts to control and prevent invasions. Larson (2005) argues that militaristic language is hurting efforts to manage invasive species because it leads to inaccurate views, social misunderstanding, xenophobia, loss of credibility, and counterproductive conservation strategies. However, his arguments do not make sense in the context of most invasive species.

For example, I have found several examples of war-like language in my own writing. In a post on miconia, a South American plant that is invading the Hawaiian Islands, I state, “Currently, over a quarter of Tahiti’s native species are threatened with extinction as a direct result of the miconia invasion” (Finn, 2011). In the post, I also use the words “takeover,” “kill,” and “eradication.” Though these words call to mind a fight against a threatening enemy, they do not exaggerate the situation. Indeed, the people of Hawaii have referred to miconia as the “purple plague” and the “green cancer.” In the context of the miconia invasion, combative language evokes an appropriate reaction to the devastating plant.

There are flaws in each of Larson’s arguments. First, he argues that militaristic language “leads to an inaccurate view of invasive species.” However, describing an invasive species in militaristic terms does not prevent a nuanced understanding of invasive species, including their potential benefits and connections to humans that caused the invasion. Contrary to Larson’s assumptions, a militaristic approach to fixing the problem of invasive species does not preclude the placement of blame on humans. In fact, painting over invasive species with a kinder brush could lead to a misconception that invasive species are a natural part of human life and cannot be avoided.

Second, Larson claims that militaristic language “contributes to social misunderstanding, charges of xenophobia, and loss of scientific credibility.” In reality, most references to invasive species are in regards to a particular species, rather than to invasive species in general (Bossenbroek et al., 2005). Beneficial species are usually not referred to with unnecessary militaristic language. Therefore, as long as readers do not generalize specific cases to the whole field of invasive species, there should be no harm in using militaristic language if the situation merits it. Additionally, for legitimate articles, charges of xenophobia stem from reader, not the scientists. Good scientific articles reference only the invasive species in question, not irrelevant information from that species’ home. It is illogical for a reader to assume an article is attacking the people from a specific location when, in reality, it targets a harmful species. Larson also argues that the war metaphor could lead to a loss of scientific credibility if it is not used discriminatingly. In any scientific pursuit, a statement that is applied incorrectly could cause the field to lose credibility. As long as invasive species remain a significant threat, the appropriate use of forceful language should not cause a loss of credibility.

Finally, he argues that combative language “reinforces the militaristic patterns of thought that are counterproductive for conservation.” Larson claims militaristic language creates a larger association between invasion biology and politics. This association is not necessarily counterproductive. More legislation needs to be enacted to successfully control existing invaders and to prevent future invasions. Furthermore, Larson’s examples demonstrating “polarization” with regards to invasive species reference opposition to control methods. Control methods often have opponents, but this opposition should not be blamed on the language in the literature.

Alternative language to war metaphors could understate the great damage that invasive species are capable of, thereby decreasing efforts to control and prevent their spread. We cannot afford to passively accept the presence of invasive species.  Combative language may be the only way to effectively convey the gravity of some biological invasions and the need to prevent and fight their spread.

Bossenbroek, J.M., McNukty, J., and R.P. Keller. 2005. Can ecologists heat up the discussion on invasive species risk? Risk Analysis 25: 1595-1597.

Finn, C.B. 2011. Miconia: the purple plague. <http://sites.duke.edu/writing20_12_s2011/2011/01/23/miconia-the-purple-plague/>

Larson, B.M.H 2005. The war of the roses: demilitarizing invasion biology. Fronteirs in Ecology and the Environment 3: 495-500.

Fifty years ago, Miconia Calvescens was only known to make its home from Mexico in the north, down to Brazil and Argentina in the south. Today, that range includes not only the original land, but several pacific island groups, thousands of miles away. In Tahiti, nearly two thirds of the existing rainforests is composed of this “green Ebola”, whereas only a relatively short time ago, it was unknown on the islands (Meyer and Florence 1996). Closer to home, on the islands of Hawaii, Miconia has also made a significant impact, and although it does not constitute as large of threat as it does in Tahiti, Hawaii is on the verge of the same ecological disaster.

The first step to understanding the threat Miconia poses on the Hawaiian islands is to look at the idea of island ecosystems. The idea is that a body of land that has been separate from the mainland for long periods of time will slowly develop unique life forms not found anywhere else in the world. This is certainly the case with Hawaii. Species such as the crested honeycreeper, the nene (a type of goose), hapu’u fern, and the ‘ahinahina (a.k.a silversword) are found only on this small island chain in the northern pacific ocean. It is species like these, and the ecosystems that they inhabit, that are most threatened by the invasion of Miconia on the islands.
The National Geographic film, “Strange Days on Planet Earth,” follows researcher Dave Duffy as he attempts to explain the Miconia’s success and develop effective methods to prevent it from becoming more widespread. The first part comes much more easily than the second. Duffy, and other researchers, have found that because of the broad leaves of miconia, the plant can easily beat out many of the native species for sunlight. This, coupled with the fact that it produces a large amount of seeds, gives this species a significant advantage over the natives. The second half of the goal, however, is much more elusive. According to the film, there is no fail-safe solution for Miconia in the Hawaiian islands. Instead, activists and researchers are forced to remove the plant mostly by hand. Although several methods have been established for locating areas of high Miconia density, these only offer a helping hand and do not directly effect the number of Miconia plants on the islands.

The approached featured in the Miconia segment of “Strange Days on Planet Earth” is far from the most desirable path. Destroying patches of Miconia by hand only acts as a way to put off an inevitable expansion of Miconia throughout the forests of the Hawaiian Islands. Even with the large amount of people who do contribute to the effort, this plant remains so widespread and located in many difficult-to-reach areas of the islands, that nearly nothing short of total extermination will end the problem. With this said, however, there currently does not exist a better solution. At the very least, this approach is preventing the further spread to this “green ebola” and ultimately helps keep a lot of the native ecosystems still intact. Still, until a final solution is found, Miconia will remain a huge threat to the Hawaiian islands.

Meyer, Jean-Yves, and Jaques Florence. “Tahiti’s Native Flora Endangered by the Invasion of Miconia Calvescens.” Journal of Biogeography 23.6 (1996): 775-81. Wiley Online Library. 1 May 2007. Web. 23 Jan. 2011. <http://onlinelibrary.wiley.com/doi/10.1111/j.1365- 2699.1996.tb00038.x/abstract>.

Miconia calvescens is an ornamental plant with a formidable tenacity and reproductive ability. A typical 10 m tall tree will produce up to 3 million seeds, up to 2 to 3 times a year. These seeds are spread by wind, water, non-native birds, and anything mud can stick to. As long as there is an opening in the canopy allowing sunlight through, most of the seeds will germinate. Miconia has thick leaves that block out sunlight, choking native plants. The seeds can stay in hibernation for 2 to 8 years, creating a “seed bank” where the mud is simply full of seeds waiting to germinate when the other plant dies. Lastly, if the plant was cut and not completely removed, it can resprout.

Miconia was introduced to Tahiti in 1937 and Hawaii in 1961 as an ornamental plant to grow in their botanical gardens. In Tahiti, these explosive growth of these plants were not appreciated until the 1980s, 44 years after its introduction. By then, Miconia was already established in Hawaii. Miconia now covers 65%-70% of Tahiti’s natural forests, destroying 1/4 of all of its native species.

To control the Miconia spread, efforts were undertaken to find an animal from its native range to serve as biocontrol. However, these ideas were scrapped as the pathogens and bugs seemed ineffective. In the end, these trees must be uprooted by hand. Hopefully, Hawaii will be able to aviod the same fate as Tahiti

http://www.comfsm.fm/~dleeling/invasive/miconia.html

http://www.hear.org/hnis/reports/HNIS-MicCal.pdf

http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Miconia_calvescens.html

Miconia calvescens, known to Hawaiian locals as the “green cancer” or “purple plague,” first came to the Hawaiian Islands in the 1960s as an ornamental plant for botanical gardens. Since its introduction, miconia has spread extensively through Maui, Big Island, and Oahu, causing major ecological damage wherever it invades. The South American plant can grow to heights of 50 ft and has large purple and green leaves. According to the HNIS Report for Miconia calvescens, the plant flowers and fruits simultaneously, usually several times each year. Miconia’s fruits are small, but they each can contain 50 to 200 seeds. It is estimated that mature trees can produce up to three million seeds each time they fruit. Non-native birds, such as the silvereye and red-vented bulbul, disperse the seeds far across the island when they consume the sweet fruit. Seeds may also spread via contaminated mud stuck to shoes, clothes, or vehicles. The seeds that fall from the trees accumulate in the soil, creating dense seeds banks that can remain dormant for years.

The Department of Land and Natural Resources of Hawaii warns Hawaiians of the dangers of miconia takeover with examples from Tahiti, which was also overrun with the plant. By the 1980s, miconia had invaded over 60 percent of the land. Currently, over a quarter of Tahiti’s native species are threatened with extinction as a direct result of the miconia invasion. Because the Hawaiian Islands are similar to Tahiti in climate and environment, miconia poses an equally large threat to Hawaiian ecosystems.

Miconia causes many problems for the ecosystem it has invaded. According to the Hawaiian Invasive Species Council, Miconia is on the Hawaiian State Noxious Weed List and has been designated one of Hawaii’s Most Invasive Horticultural Plants. It can harm the natural ecosystem in several ways. Miconia’s enormous leaves create large amounts of shade, killing all native species that require heavy sunlight for survival. Miconia also causes problems with erosion because its roots are not as deep as the roots of the native plants. As a result, there is less to hold the soil in place, which, in some cases, causes massive landslides, further harming the native ecosystem.

The film “Strange Days on Planet Earth” opens its segment on the Hawaiian miconia invasion with dramatic images of the massive amounts of erosion on the island. The film then shows the plant in the wild and gives background on the situation. Even more than the effects of myconia on the ecosystem, the film emphasizes the eradication efforts Hawaiians have taken against miconia.  The film shows high-tech removal operations that use aerial photography to find populations of miconia that are inaccessible by foot.  Those populations are then sprayed with an herbicide. People have also been uprooting the plants manually. However, miconia’s seeds, which fall into the soil in large quantities, pose a large problem to both eradication methods. Because they are difficult to kill with pesticides and can remain dormant for up to ten years, the populations of miconia must be monitored for years after the original plants are killed. New sprouts that spread their own seeds could reverse all of the previous eradication efforts. Removing the plants completely would require constant vigilance for several years. Five years after the film “Strange Days on Planet Earth” was filmed, it would be interesting to see if the eradication methods shown in the film were effective.