Pueraria montana var. lobata
Invasive Plants Are there benefits in cultivating invasive plants and can they improve the environments they invade?
Chris Vetrano
12/20/13
Plant Ecology
Are there benefits in cultivating invasive plants and can they improve the environments they invade? Intro – Plants and their Environments Plant environments vary all over the world, an important regulating component is the weather. Sunlight, temperature, and precipitation play an important role in the survival of plants. “Other plants and animals that live in the same area are also included in the environment of a plant. All these factors form what is called a natural community.” (Blue Planet Biomes, nd) Plants can thrive in a variety of soil types and conditions, plant development is directly related to how they interact with the environment, and it also has an effect on plant ecosystems. (Mech, Prusinkiewicz, 1996) Even in the harshest of conditions, plants have adapted and evolved over millions of years. For instance, Cactus have found ways to adapt to the desert. “However, for a plant to survive in such harsh conditions, it must have the ability to maximize its use of scarce resources, such as water and nutrients. Many species of cactus have long, sharp spines, like this Opuntia to protect its scarce stored resources from predators.” (Boundless, nd) A study that focused on epigenomes from plants collected from around the world, interestingly showed epigenomes of the same species were different. (Ecker, 2013) “By understanding epigenomic alterations in plants, scientists may be able to manipulate them for various purposes, including biofuels and creating crops that can withstand stressful events such as drought.” (Ecker, 2013) Understanding how plants thrive in different environments is important, as well as understanding how they adapt to these environments. I.
What is an Invasive Plant?
According to the United States National Arboretum invasive species can; 1. “Produce large numbers of new plants each season.” (USNA, 2009) 2. “Tolerate many soil types and weather conditions.” (USNA, 2009) 3. “Spread easily and efficiently, usually by wind, water, or animals.” (USNA, 2009) 4. “Grow rapidly, allowing them to displace slower growing plants.” (USNA, 2009) 5. “Spread rampantly when they are free of the natural checks and balances found in their native range.” (USNA, 2009) With a price tag of $100 million, for the cost of combating invasives, (in wetlands alone) it is important to determine if spending this amount of money is worth it. (USNA, 2009) Invasive plants are usually weedy and spread aggressively displacing native plants. They are commonly found on disturbed soils and have the ability to invade existing ecosystems. (Envirothonpa, nd)
Interestingly though, many invasive plants were initially introduced for erosion control, food, forage, wildlife habitat, aesthetics, and medicinal uses. Urban landscapes have also be the introductory source of exotics, which may become invasive, along with accidental transportation of seeds or plants through international trade routes. (ODNR, nd) No matter how a plant is distributed, the fact remains that plants will continue to find places they can thrive, just as humans do and interestingly humans are far more invasive than any plant could ever be.
II.
How can Plants be utilized once they Invade an Area?
With invasive species everywhere these days the cost to control them takes significant time and money. “Cornel University reports $34.7 billion spent annually on combating the effects of invasives on the nation’s agriculture, water quality, wildlife, and recreation.” There are better ways to deal with invasives, which are similar to the reasons some of them arrived in distant lands to begin with. Uses such as, Biofuels, Food, Medicines, and even as a solution for an Organic Pesticide. Instead of destroying plants and saturating soils with toxic chemicals, we need to be more responsible and harvest them, we need to make use of these amazing plants. Plants travel around just as we do, “At times, however, these invading plants seen even to precede the charge: often, potent medicinal plants colonize territory before the invasion of the very pathogens and toxins they cure.” (Scott, 2010) Plants go where they are needed it seems, sometime we just need to let nature take its course. Exhausting resources when you consider the odds of controlling invasives seems foolish. As we adapt to our surrounding, so do plants and as we change the landscapes around the world, plants will follow and fill in the gaps between the concrete, with life. Many invasive exotics (IE) are edible and recipes for cooking with exotics are available on the internet. Here is a link to a collection of recipes for a variety of invasive plants. http://www.eddmaps.org/ipane/weedwisdom/recipe.htm Steve Brill, whom I met at Farmingdale State College, in April 2012, took a group of us around campus and pointed out many edible weeds, one of them was Garlic mustard. There is an event held by The Appalachian Trail Conservancy called the “Great Garlic Mustard Gathering” which challenges volunteers to remove and utilize invasive plants from the Appalachian Trail. “In preparation for this event, people have already expressed interest in baking pies with young Japanese knotweed shoots, brewing tea made from multiflora rose hips and experimenting with other IE plant recipes.” (ATC, nd) Many invasive exotics have medicinal uses also. “Many other IE species, if not edible, have certain properties that can be used to our benefit. For example, vines like kudzu and Japanese honeysuckle have been used for centuries for their medicinal properties and also for weaving baskets.” (ATC, nd) Another use for giant knotweed is to take advantage of its natural properties as a pesticide. Marrone Organic Innovations has introduced a solution, a “green” pesticide obtained from an extract of the giant knotweed, which has enormous potential in organic farming. “Bio-pesticides are derived from plants, microbes, or other natural materials and are proven to be safer for humans and the environment.” (Science Daily, 2008)
Medicinal uses of Invasive Plants. There are many invasive plants that have medicinal uses “Plants provide many useful drugs. Some of these plants have been used as medicines for hundreds of years. The bark of the cinchona tree was used 400 years ago to reduce fever. It is still used to make quinine, a drug used to treat malaria and other diseases. Another drug, called digitalis, is used in treating heart disease. It is made from the dried leaves of the purple foxglove plant. The roots of the Mexican yam are used in producing cortisone, a drug useful in treating arthritis and a number of other diseases.” (Blue Planet Biomes, nd) Japanese knotweed is an amazing medicinal with a rapid growth rate. “Japanese knotweed grows at least two inches per day, creating high biomass and leading to two to three harvest per year.” (Scott, 2010) It has high amounts of resveratrol, more than any other plant in the world. (Scott, 2010) Resveratrol reduces the risk for cardiovascular disease and cancer by preventing the oxidation of LDL “bad” cholesterol. Nutritional information regarding knotweed is impressive also. It is an excellent source of vitamin A, vitamin C, and rutin. Knotweed also contains potassium, phosphorus, zinc, and manganese. (Steve Brill, nd) Another invasive plant that has medicinal qualities is Pueraria montana, commonly called Kudzu. “Kudzu has for centuries been a staple among Chinese herbal medicines. The sixteenth century manual of medicinal herbs by Shih-Chen Li recommends the root be used for its antipyretic and antiemetic actions, and as a treatment for poisoning. Kudzu seeds and flowers were prescribed for ailments associated with alcoholic excess, and the leaves applied to wounds to facilitate healing.” (Marat, 2013)
III.
Invasive Plants used as Biofuel.
There are several invasives that can be used for Biofuel. Pennisetum purpureum (commonly called napier grass), Pueraria montana, commonly called Kudzu, and Arundo donax commonly called giant reed, are all potential sources for Biofuels. Kudzu, aside from having medicinal qualities, also is a contender for use as a Biofuel. “If economical harvesting and processing techniques could be developed, the kudzu infesting North America has the potential to supplement existing bioethanol feedstocks, which could be of significance to the rural economy of the southeastern USA.” (Sage, et. al., 2009) As recently as July 2, 2013 the EPA is allowing bio-fuels to be made from two invasive species. “Arundo donax (also known as giant reed) assessed by the U.S. Department of Agriculture as being a high-risk species and Pennisetum purpureum (commonly called napier grass), to qualify as cellulosic biofuel feedstocks under the Renewable Fuel Standard.” (Beans, 2013)
IV.
Rethinking Invasive Plants.
Invasive plants seem to get bad publicity and it is mostly out of fear they are harming the environments that they are invading, although there seems to be evidence that is not necessarily the case. “Implicit in the proposals that call for eradicating or banning exotic invasive species is the assumption that native vegetation will return to dominance once invasives are removed. That is the theory; the reality, of course, can be quite different. Land managers and others who have to deal with the invasive problem on the ground know that more often than not the old invasive species comes back following removal, or else a new invader moves in to replace the old one.” (Del_Tredici, 2006) By trying to restore landscapes we may be biting off more than we can chew and truthfully it’s not necessary. “Is ‘landscape restoration’ really just good horticulture dressed up with jargon to simulate ecology, or is it based on scientific theories with testable hypotheses?” To put it another way: Can we ever really put the invasive-species genie back in the bottle, or are we looking at a future in which nature as we know it becomes a cultivated entity.” (Del_Tredici, 2006) Studies show that there are benefits from invasive plants and sometimes they benefit insects. “A recent survey by Mr. Abhineshwar Prasad of The University of the South Pacific, reported over 100 species of arthropods associated with road side patches of S. trilobata, including Hymenoptera such as parasitoid wasps, honey bees and solitary bees. One species of solitary bee, Braunsapis puangensis was locally abundant on patches of S. trilobata in the Laucala Bay area of Suva. This bee species is probably of Indian origin and was most likely carried to Fiji by anthropogenic means.” (Science Daily, 2013) In another study it was also found that there was an increase in pollinators within habitats. According to Dr. Simon Hodge from Lincoln University in New Zealand. “Pollination success of generalist plants tends to be positively related to pollinator diversity, so any habitat modifications that increase the number of pollinating species present at a site would tend to be of some inherent value.” (Science Daily, 2013) An article published in the “Oecología” [Oecology] journal by scientists at the Universidad Autónoma de Barcelona (UAB) found “the existence of invasive plants in invaded sites can increase visits from insects to the majority of native plants.” (Science Daily, 2008) Hybridization is a natural occurrence and according to an article by Carl Zimmer in the NY Times, a paper published in August 2008, in Proceedings of the National Academy of Sciences by Dov Sax, an ecologist at Brown University, and Steven D. Gaines, a marine biologist at the University of California, Santa Barbara, it is not the cause for native plant species extinction. Of the 22,000 non-native plants in New Zealand, 2069 have become naturalized. Although, the number of native plant species that have gone extinct in New Zealand, is only three. (Zimmer, 2008) The biggest argument that invasive species are a threat, is the speed at which they are invading, as compared to historic records and also the current environmental impact. Dr. Sax as well as Dr. Gains argue that the attitude about exotic species are too simplistic. (Zimmer, 2008) Sax believes it is predators rather than competitors that is the issue. The paper analyzed all
documented extinctions of vertebrates which have been associated with invasive species and found four-fifths of the extinctions were caused by predators. “Dr. Sax and Dr. Gaines argue that competition from exotic species shows little sign of causing extinctions. This finding is at odds with traditional concepts of ecology, Dr. Sax said. Ecosystems have often been seen as having a certain number of niches that species can occupy. Once an ecosystem’s niches are full, new species can take them over only if old species become extinct.” (Zimmer, 2008) According to these scientists “exotics can actually spur the evolution of new diversity. “Historic evidence of this is found in England. “Saltmarsh cordgrass was introduced into England in the 19th century, where it interbred with the native small cordgrass. Their hybrid offspring could not reproduce with either original species, producing a new species called common cordgrass.” Nature will persists and from the data presented here it seems nature knows a little more than we give it credit for. Dr. Brown of the University of New Mexico and his colleagues realize invasive species can spatially dislocate native species but they say “native species are not becoming extinct, because they compete better than the invasive species in certain refuges.” (Zimmer, 2008) “Many other invasive plants, such as Russian olive, Scotch broom, and dandelion, help accumulate nitrogen and other trace elements to enrich depleted soils, which can also lessen the need for chemical fertilizers on agricultural lands.” (Scott, 2010)
V.
Conclusion
The inevitable change of the landscape offers continuous evolution of all plant species. Targeting the ones that thrive better than others, seems to go against nature. Adapting to these changes and taking advantage of the benefits from these plants is far more advantageous than trying to fight nature. Plants will do what they have to in order to survive. If we begin to redirect our energies to coincide with plants, we will find that the rewards are enormous. The mentality of war seems to be deeply rooted in the psyche of humans, why else would we be in a botanical war for over 65 years, with no end in sight.
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